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1
Ebersbach, Celina, Alicia-Marie K. Beier, Christian Thomas, and Holger H. H. Erb. "Impact of STAT Proteins in Tumor Progress and Therapy Resistance in Advanced and Metastasized Prostate Cancer." Cancers 13, no. 19 (September 28, 2021): 4854. http://dx.doi.org/10.3390/cancers13194854.
Abstract:
Signal transducers and activators of transcription (STATs) are a family of transcription factors involved in several biological processes such as immune response, cell survival, and cell growth. However, they have also been implicated in the development and progression of several cancers, including prostate cancer (PCa). Although the members of the STAT protein family are structurally similar, they convey different functions in PCa. STAT1, STAT3, and STAT5 are associated with therapy resistance. STAT1 and STAT3 are involved in docetaxel resistance, while STAT3 and STAT5 are involved in antiandrogen resistance. Expression of STAT3 and STAT5 is increased in PCa metastases, and together with STAT6, they play a crucial role in PCa metastasis. Further, expression of STAT3, STAT5, and STAT6 was elevated in advanced and high-grade PCa. STAT2 and STAT4 are currently less researched in PCa. Since STATs are widely involved in PCa, they serve as potential therapeutic targets. Several inhibitors interfering with STATs signaling have been tested unsuccessfully in PCa clinical trials. This review focuses on the respective roles of the STAT family members in PCa, especially in metastatic disease and provides an overview of STAT-inhibitors evaluated in clinical trials.
2
Lee, Hyun-Ku, Gita Singh, and Sujay Singh. "STAT reporter cell line systems as a tool for cancer therapeutic target screening." Journal of Immunology 200, no. 1_Supplement (May 1, 2018): 169.8. http://dx.doi.org/10.4049/jimmunol.200.supp.169.8.
Abstract:
Abstract Signal transducer and activator of transcription (STAT) proteins as cytoplasmic transcription factors respond to cytokines and growth factors that mediate downstream signaling. STATs are closely related with cancers as they are frequently found to be dysregulated in primary tumors, leading to enhanced survival of tumors and increased angiogenesis. Among seven STAT family members, STAT3, STAT4 and STAT5 are considered to primarily promote cancer development and progression, while STAT1 may function either as a tumor suppressor or tumor promoter. STAT3, 4 and 5 are persistently activated in many human cancer cell lines, leading to increased cancer cell survival. Several studies demonstrate that inhibition of STAT3 or STAT5 signaling decreases cancer cell proliferation leading to apoptosis. Taken together, these indicate that STAT proteins can be ideal targets for anti-cancer therapy, and so it is crucial to develop assay systems that can identify inhibitors targeting those pro-tumorigenic STATs. Hence we developed the four reporter cell lines, each of which stably expresses STAT1-, STAT3-, STAT4-, or STAT5-response element that controls an optimized Renilla luciferase reporter gene upon stimulation. Functional activity of each cell line was evaluated through dose response of various cytokines such as IFNs, IL-3 and IL-6. One of the STAT inhibitors, curcumin as well as other putative STAT suppressors were utilized to characterize how each STAT can differentially respond to each test molecule and how its response can affect the host cells.
3
Jones, Dan, Justin Windham, Brian Stewart, Luis Fayad, Alma Rodriguez, and Fredrick B. Hagemeister. "Differential JAK-STAT Pathway Activation in Primary Mediastinal Large B-Cell Lymphoma: Two Subgroups with Differential Cytokine Activation Patterns and Predicted Responses to Kinase Inhibitors." Blood 114, no. 22 (November 20, 2009): 968. http://dx.doi.org/10.1182/blood.v114.22.968.968.
Abstract:
Abstract Abstract 968 Background: Primary mediastinal large B-cell lymphoma (PMBCL) is a specialized type of diffuse large B-cell lymphoma which shows diagnostic and pathogenetic overlap with mediastinal classical Hodgkin lymphoma. Approximately 60% of patients with PMBCL have good response to conventional chemoradiotherapy with the rest often showing distant relapses. Microarray studies of PMBCL have revealed overexpression of components and targets of the JAK-STAT signaling pathways including upregulation of IL13 receptor and STAT1; a subset of PMBCL have genome amplification of JAK2 or deletion of the JAK suppressor SOCS1. Given this complexity, we examined the most common mechanism and effects of JAK-STAT dysregulation in a series of newly diagnosed and recurrent PMBCL. Methods: Fifty-three biopsies from 23 patients with PMBCL were assessed and correlated with outcome. JAK2 and SOCS1 copy number status were determined by quantitative PCR on genomic DNA. JAK-STAT pathway activation was probed using reverse transcription quantitative (RQ)-PCR for JAK2, JAK3, and a panel of IL-4 and IL-13 transcriptional targets. JAK-STAT activation was assessed in tissue arrays using antisera against phospho-activation epitopes of STAT1, STAT3, STAT5, and STAT6 using immunohistochemistry (IHC). Activation patterns were modeled in the PMBCL cell line Karpas (K)1106P at baseline and following IL-4 and IL-13 stimulation with or without a range of small molecule inhibitors and blocking antibodies. Growth parameters were measured by MTT and protein levels by flow cytometry, Western blot, RQ-PCR and kinase profiling. Results: JAK2 genomic amplification was present in 40% of PMBCL and SOCS1 deletion in 10% as well as in the K1106P line. By phospho-activation IHC, tumors in 20/23 (87%) patients showed STAT activation, mostly due to STAT1 (60.8%) followed by STAT3 (26.1%), with 6 cases showing mixed patterns. In different tumors, localized and uniform STAT activation patterns were seen. Constitutive STAT activation was correlated with high expression of IL-4 transcription targets including CCL17 and IL13RA as well as JAK2 autophosphorylation and inferior outcome (p = .007). Tumors with more localized foci of activation were associated with alternate transcription patterns. In the K1106P cell line, IL-4 but not IL-13 treatment led to inducible STAT1 activation whereas baseline STAT3/6 activation was highly regulated by cytokine exposure. The JAK2 inhibitor JSI124 blocked IL-4 induced STAT1 activation whereas the JAK inhibitors AG-490, NSC7908 and WHI-P154 did not but did block IL-4/IL-13-induced STAT3 activation. The JAK3 inhibitor ZM39923 was most effective in blocking cell growth but did not block STAT1 activation. Conclusions: JAK2-STAT pathway activation characterizes nearly all cases of PMBCL but genetic mechanisms are distinct leading to distinct patterns of STAT1 activation (driven predominantly through the type I IL-4 receptor) and STAT3/6 activation (driven predominantly through the type II IL13RA/IL4RA) with differential effects on growth parameters and gene regulation. The patterns of STAT activation and target gene expression in primary tumors comprising these two groups mirrored the response to small molecule inhibitors following cytokine exposure in vitro in the K1106P line and highlights differences between IL-4 and IL-13 signaling in PMBCL. Profiling of PMBCL biopsies with phosphoactivation IHC for STAT isoforms may be useful to subcategorize cases and select the optimal JAK-STAT pathway inhibitors for adjuvant therapy. Disclosures: No relevant conflicts of interest to declare.
4
Standing, David, Emma Feess, Satvik Kodiyalam, Michael Kuehn, Zachary Hamel, Jaimie Johnson, Sufi Mary Thomas, and Shrikant Anant. "The Role of STATs in Ovarian Cancer: Exploring Their Potential for Therapy." Cancers 15, no. 9 (April 26, 2023): 2485. http://dx.doi.org/10.3390/cancers15092485.
Abstract:
Ovarian cancer (OvCa) is a deadly gynecologic malignancy that presents many clinical challenges due to late-stage diagnoses and the development of acquired resistance to standard-of-care treatment protocols. There is an increasing body of evidence suggesting that STATs may play a critical role in OvCa progression, resistance, and disease recurrence, and thus we sought to compile a comprehensive review to summarize the current state of knowledge on the topic. We have examined peer reviewed literature to delineate the role of STATs in both cancer cells and cells within the tumor microenvironment. In addition to summarizing the current knowledge of STAT biology in OvCa, we have also examined the capacity of small molecule inhibitor development to target specific STATs and progress toward clinical applications. From our research, the best studied and targeted factors are STAT3 and STAT5, which has resulted in the development of several inhibitors that are under current evaluation in clinical trials. There remain gaps in understanding the role of STAT1, STAT2, STAT4, and STAT6, due to limited reports in the current literature; as such, further studies to establish their implications in OvCa are necessitated. Moreover, due to the deficiency in our understanding of these STATs, selective inhibitors also remain elusive, and therefore present opportunities for discovery.
5
Rodman, Esther, Michael Emch, Elizabeth Bruinsma, Xiaonan Hou, John Weroha, and John Hawse. "Abstract 1129: Interrogating JAK/STAT signaling in ovarian cancer as a potential oncogenic driver and therapeutic target." Cancer Research 82, no. 12_Supplement (June 15, 2022): 1129. http://dx.doi.org/10.1158/1538-7445.am2022-1129.
Abstract:
Abstract Ovarian cancer is the 7th most common cancer in women. It is the most fatal of all female reproductive cancers, due to the 5-year overall survival of 10-30% and over half of patients being diagnosed with late-stage disease. Despite initial response to front line platinum- and taxol-based chemotherapies, over 70% of patients develop recurrent and chemotherapy resistant disease and nearly all of these women die of their disease. Recently, the use of targeted therapies such as bevacizumab and PARP inhibitors have been shown to improve progression-free survival. However, these regimens have thus far failed to improve overall survival in patients without specific genetic signatures, highlighting the urgent need for alternative therapies. We have identified lestaurtinib as a potent inhibitor of many ovarian cancer cell lines, including platinum and PARP inhibitor resistant models, and patient derived organoid models. RNA-sequencing following lestaurtinib treatment identified JAK/STAT signaling as one of the most profoundly downregulated pathways. Additionally, it was recently reported via single cell RNA sequencing of patient tumors that downstream mediators of the JAK/STAT pathway are among the most highly expressed genes in ovarian tumor cells. Further, we have discovered that STAT1 and STAT3 are constitutively activated in chemotherapy and PARP inhibitor resistant cell lines as reflected by high levels of Tyr701/705 and Ser727 phosphorylation suggesting induction of this pathway may drive resistance. Selective siRNA-mediated knockdown of STAT1/3 resulted in significant growth inhibition confirming their importance in maintaining cell viability. Surprisingly, we have identified profound differences in the ability of various JAK/STAT inhibitors to suppress ovarian cancer cell growth. For example, ruxolitinib, the only JAK/STAT inhibitor currently in clinical trials for ovarian cancer, failed to inhibit the growth sensitive, platinum resistant or PARP inhibitor resistant cell lines. Our preliminary data indicate that JAK/STAT inhibitor efficacy in preventing ovarian cancer cell growth is related to their ability to block specific phosphorylation events on STAT1/3 proteins. We believe that precise and selective inhibition of STAT1 and STAT3 signaling represents a robust, durable, and novel approach for the treatment of highly aggressive and resistant forms of ovarian cancer. Further we plan to elucidate the molecular mechanisms by which STAT1 and STAT3 function to support ovarian cancer cell viability and growth, in order to substantially advance our understanding of JAK/STAT signaling in ovarian cancer and to identify the most effective ways to pharmacologically inhibit JAK/STAT signaling in ovarian cancer cells. Outcomes from this work will have both immediate and long-term impacts for our patients and will lay the foundation for future biomarker-driven clinical trials. Citation Format: Esther Rodman, Michael Emch, Elizabeth Bruinsma, Xiaonan Hou, John Weroha, John Hawse. Interrogating JAK/STAT signaling in ovarian cancer as a potential oncogenic driver and therapeutic target [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1129.
6
Zhou, Jianbiao, Chonglei Bi, Lai Fong Poon, Viraj J. Janakakumara, Jiaying Khng, Hanry Yu, Keith B. Glaser, Daniel H. Albert, Davidsen K. Davidsen, and Chien-Shing Chen. "Overactivation of STAT Pathways and Overexpression of Survivin Confer Resistance to FLT3 Inhibitors and Could Be Therapeutic Targets in AML." Blood 110, no. 11 (November 16, 2007): 2367. http://dx.doi.org/10.1182/blood.v110.11.2367.2367.
Abstract:
Abstract Internal tandem duplication (ITD) of fms-like tyrosine kinase 3 (FLT3) receptor plays an important role in the pathogenesis of acute myeloid leukemia (AML). A number of small molecule kinase inhibitors are currently proceeding in different phases of clinical trials. As with imatinib in CML, leukemic cells could develop resistance to these RTK inhibitors when used as monotherapy. Mutations in the ATP-binding pocket have been identified through PCR-based mutagenesis screening in Ba/F3-FLT3-ITD cells and selected for growth in the presence of PKC412, or in a resistant Ba/F3-FLT3-ITD cell line developed by cocultured with SU5416. Resistance to PKC412 resulting from the N676K point mutation in the FLT3 kinase domain has been described in a clinical trial patient. Selection of activating Ras mutations has been found in 2 out of 6 FLT3 inhibitor resistant cell lines, but no point mutation of FLT3 kinase domain was found in all 6 resistant cell lines. To further investigate other potential mechanisms of resistance to FLT3 inhibitors, we developed a resistant cell line by long-term culture of MV4-11 cells with ABT-869, designated as MV4-11-R (IC50: 52 vs 6 nM for the parental MV4-11 cell line), which is also cross resistant to other structurally unrelated inhibitors including SU5416, AG1296 and a FLT3 inhibitor III (MERCK). No point mutation in the kinase domain of FLT3 was found in MV4-11-R cells. Western blot and FACS analysis excluded overexpression of p-FLT3, FLT3 or 3 multidrug resistance related proteins (MDR, MRP1 and LRP) in this resistant line. Gene expression profiling revealed up-regulation of FLT3 ligand (FLT3LG) (2.4 fold) and Survivin (2 fold), while down-regulation of SOCS1, SOCS2, and SOCS3 was observed in MV4-11-R compared to MV4-11 parental cells. Overexpression of FLT3LG and Survivin was also demonstrated at the protein level. Survivin is a unique member of the inhibitor of apoptosis proteins (IAP) family and a known target of the STAT3 pathway. Down-regulation of suppressor of cytokine signaling (SOCS) proteins (negative regulators of STAT pathways) was observed even in the presence of overactivation of the STAT1, STAT3 and STAT5 pathways in the MV4-11-R line. We screened a panel of small molecule inhibitors including a STAT inhibitor (indirubin derivative IDR E804), 3 JAK inhbitors (Tyrene CR4, AG490, and JAK3 Inhibitor II), and a CDK/survivin inhibitor (NU6140). We found that MV4-11-R is most sensitive to IDR E804 (an inhibitor of CDKs and the SRC-STAT3 pathway). The IC50 value of ABT-869 in MV4-11-R was decreased from 52 to 6.2 nM in the presence of 2 nM of IDR E804. Further validation of the therapeutic effect of IDR E804 in combination with ABT-869 in the MV4-11-R mouse xenograft model is ongoing. Targeting Survivin by shRNA and a dominant-negative vector (survivin-T34A) induced MV4-11-R to undergo apoptosis. Taken together, these results demonstrate that overactivation of STAT pathways and overexpression of survivin are the main mechanism of resistance to ABT-869; suggesting that the STAT pathways and survivin could be potential targets for the treatment of patients who develop resistance to FLT3 inhibitors.
7
Suzuki, Asuka, Toshikatsu Hanada, Keiichi Mitsuyama, Takafumi Yoshida, Shintaro Kamizono, Tomoaki Hoshino, Masato Kubo, et al. "Cis3/Socs3/Ssi3 Plays a Negative Regulatory Role in Stat3 Activation and Intestinal Inflammation." Journal of Experimental Medicine 193, no. 4 (February 12, 2001): 471–82. http://dx.doi.org/10.1084/jem.193.4.471.
Abstract:
Immune and inflammatory systems are controlled by multiple cytokines, including interleukins (ILs) and interferons. These cytokines exert their biological functions through Janus tyrosine kinases and signal transducer and activator of transcription (STAT) transcription factors. We recently identified two intrinsic Janus kinase (JAK) inhibitors, JAK binding protein (JAB; also referred to as suppressor of cytokine signaling [SOCS1]/STAT-induced STAT inhibitor [SSI1]) and cytokine-inducible SH2 protein (CIS)3 (or SOCS3/SSI3), which play an essential role in the negative regulation of cytokine signaling. We have investigated the role of STATs and these JAK inhibitors in intestinal inflammation. Among STAT family members, STAT3 was most strongly tyrosine phosphorylated in human ulcerative colitis and Crohn's disease patients as well as in dextran sulfate sodium (DSS)-induced colitis in mice. Development of colitis as well as STAT3 activation was significantly reduced in IL-6–deficient mice treated with DSS, suggesting that STAT3 plays an important role in the perpetuation of colitis. CIS3, but not JAB, was highly expressed in the colon of DSS-treated mice as well as several T cell–dependent colitis models. To define the physiological role of CIS3 induction in colitis, we developed a JAB mutant (F59D-JAB) that overcame the inhibitory effect of both JAB and CIS3 and created transgenic mice. DSS induced stronger STAT3 activation and more severe colitis in F59D-JAB transgenic mice than in their wild-type littermates. These data suggest that hyperactivation of STAT3 results in severe colitis and that CIS3 plays a negative regulatory role in intestinal inflammation by downregulating STAT3 activity.
8
Galli Sanchez, Ana Paula, Tatiane Ester Aidar Fernandes, and Gustavo Martelli Palomino. "The JAK-STAT Pathway and the JAK Inhibitors." Journal of Clinical Research in Dermatology 7, no. 5 (November 30, 2020): 1–6. http://dx.doi.org/10.15226/2378-1726/7/5/001128.
Abstract:
Dozens of cytokines that bind Type I and Type II receptors use the Janus Kinases (JAK) and the Signal Transducer and Activator of Transcription (STAT) proteins pathway for intracellular signaling, orchestrating hematopoiesis, inducing inflammation, and controlling the immune response. Currently, oral JAK inhibitors are being used to treat many inflammatory and myeloproliferative diseases and are also under investigation in several clinical trials for skin diseases. Thus, dermatologists should understand how the JAK-STAT pathway works as well as the mechanism of action of the JAK inhibitors which will certainly become an important part of the dermatologist’s treatment armamentarium in the next few years. Keywords: JAK inhibitors; Janus Kinases; JAK-STAT Pathway List of Abbreviations: AD: Atopic Dermatitis ADP: Adenosine diphosphate Dmards: Disease-Modifying Antirheumatic Drugs JAK: Janus kinase(s) Jaki: Janus kinase Inhibitor(s) PIAS: Protein Inhibitor of Activated STAT P-STAT: Phosphorylated STAT STAT: Signal Transducer and Activator of Transcription TYK2: Tyrosine Kinase 2 Wsxws: Tryptophan-Serine-X-Tryptophan-Serine
9
Wang, Weiyuan, Melanie Cristina Lopez McDonald, Rajashree Hariprasad, Tiara Hamilton, and David A. Frank. "Oncogenic STAT Transcription Factors as Targets for Cancer Therapy: Innovative Strategies and Clinical Translation." Cancers 16, no. 7 (March 31, 2024): 1387. http://dx.doi.org/10.3390/cancers16071387.
Abstract:
Despite advances in our understanding of molecular aspects of oncogenesis, cancer remains a leading cause of death. The malignant behavior of a cancer cell is driven by the inappropriate activation of transcription factors. In particular, signal transducers and activators of transcription (STATs), which regulate many critical cellular processes such as proliferation, apoptosis, and differentiation, are frequently activated inappropriately in a wide spectrum of human cancers. Multiple signaling pathways converge on the STATs, highlighting their importance in the development and progression of oncogenic diseases. STAT3 and STAT5 are two members of the STAT protein family that are the most frequently activated in cancers and can drive cancer pathogenesis directly. The development of inhibitors targeting STAT3 and STAT5 has been the subject of intense investigations in the last decade, although effective treatment options remain limited. In this review, we investigate the specific roles of STAT3 and STAT5 in normal physiology and cancer biology, discuss the opportunities and challenges in pharmacologically targeting STAT proteins and their upstream activators, and offer insights into novel therapeutic strategies to identify STAT inhibitors as cancer therapeutics.
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Hu, Cheng-Ping, Jun-Tao Feng, Yu-Ling Tang, Jin-Qi Zhu, Min-Juan Lin, and Ming-En Yu. "LIF Upregulates Expression of NK-1R in NHBE Cells." Mediators of Inflammation 2006 (2006): 1–8. http://dx.doi.org/10.1155/mi/2006/84829.
Abstract:
Leukemia inhibitory factor (LIF), a cytokine at the interface between neurobiology and immunology, is mainly mediated through JAK/STAT pathway and MAPK/ERK pathway. Evidence suggested LIF is related to the higher expression of neurokinin-1 receptor (NK-1R) in asthma. In this study, the immunohistochemistry stain showed the expressions of NK-1R, LIF, p-STAT3, and p-ERK1/2 in the lung tissues of allergic rats were increased compared with the controls, and the main positive cell type was airway epithelial cell. Normal human bronchial epithelial cells were treated with LIF in the presence or absence of AG490 (JAK2 inhibitor), PD98059 (MEK inhibitor), and the siRNA against STAT3. Western blot and RT-PCR indicated that LIF induced the expression of NK-1R, which was inhibited by the inhibitors mentioned above. No significant interaction was found between JAK/STAT pathway and MAPK/ERK pathway. In summary, bronchial epithelial cell changes in asthma are induced by LIF which promotes the expression of NK-1R, and JAK/STAT pathway and MAPK/ERK pathway may participate in this process.
11
Tolomeo, Manlio, Maria Meli, and Stefania Grimaudo. "STAT5 and STAT5 Inhibitors in Hematological Malignancies." Anti-Cancer Agents in Medicinal Chemistry 19, no. 17 (January 24, 2020): 2036–46. http://dx.doi.org/10.2174/1871520619666190906160848.
Abstract:
The JAK-STAT pathway is an important physiologic regulator of different cellular functions including proliferation, apoptosis, differentiation, and immunological responses. Out of six different STAT proteins, STAT5 plays its main role in hematopoiesis and constitutive STAT5 activation seems to be a key event in the pathogenesis of several hematological malignancies. This has led many researchers to develop compounds capable of inhibiting STAT5 activation or interfering with its functions. Several anti-STAT5 molecules have shown potent STAT5 inhibitory activity in vitro. However, compared to the large amount of clinical studies with JAK inhibitors that are currently widely used in the clinics to treat myeloproliferative disorders, the clinical trials with STAT5 inhibitors are very limited. At present, a few STAT5 inhibitors are in phase I or II clinical trials for the treatment of leukemias and graft vs host disease. These studies seem to indicate that such compounds could be well tolerated and useful in reducing the occurrence of resistance to tyrosine kinase inhibitors in chronic myeloid leukemia. Of interest, STAT5 seems to play an important role in the regulation of hematopoietic stem cell self-renewal suggesting that combination therapies including STAT5 inhibitors can erode the cancer stem cell pool and possibly open the way for the complete cancer eradication. In this review, we discuss the implication of STAT5 in hematological malignancies and the results obtained with the novel STAT5 inhibitors.
12
Orlova, Anna, Christina Wagner, Elvin D. de Araujo, Dávid Bajusz, Heidi A. Neubauer, Marco Herling, Patrick T. Gunning, György M. Keserű, and Richard Moriggl. "Direct Targeting Options for STAT3 and STAT5 in Cancer." Cancers 11, no. 12 (December 3, 2019): 1930. http://dx.doi.org/10.3390/cancers11121930.
Abstract:
Signal transducer and activator of transcription (STAT)3 and STAT5 are important transcription factors that are able to mediate or even drive cancer progression through hyperactivation or gain-of-function mutations. Mutated STAT3 is mainly associated with large granular lymphocytic T-cell leukemia, whereas mutated STAT5B is associated with T-cell prolymphocytic leukemia, T-cell acute lymphoblastic leukemia and γδ T-cell-derived lymphomas. Hyperactive STAT3 and STAT5 are also implicated in various hematopoietic and solid malignancies, such as chronic and acute myeloid leukemia, melanoma or prostate cancer. Classical understanding of STAT functions is linked to their phosphorylated parallel dimer conformation, in which they induce gene transcription. However, the functions of STAT proteins are not limited to their phosphorylated dimerization form. In this review, we discuss the functions and the roles of unphosphorylated STAT3/5 in the context of chromatin remodeling, as well as the impact of STAT5 oligomerization on differential gene expression in hematopoietic neoplasms. The central involvement of STAT3/5 in cancer has made these molecules attractive targets for small-molecule drug development, but currently there are no direct STAT3/5 inhibitors of clinical grade available. We summarize the development of inhibitors against the SH2 domains of STAT3/5 and discuss their applicability as cancer therapeutics.
13
Zhou, Jianbiao, Chonglei Bi, Jasinghe V. Janakakumara, Shaw-Cheng Liu, Wee-Joo Chng, Kian-Ghee Tay, Lai-Fong Poon, et al. "Enhanced activation of STAT pathways and overexpression of survivin confer resistance to FLT3 inhibitors and could be therapeutic targets in AML." Blood 113, no. 17 (April 23, 2009): 4052–62. http://dx.doi.org/10.1182/blood-2008-05-156422.
Abstract:
Abstract To further investigate potential mechanisms of resistance to FLT3 inhibitors, we developed a resistant cell line by long-term culture of MV4-11 cells with ABT-869, designated as MV4-11-R. Gene profiling reveals up-regulation of FLT3LG (FLT3 ligand) and BIRC5 (survivin), but down-regulation of SOCS1, SOCS2, and SOCS3 in MV4-11-R cells. Hypermethylation of these SOCS genes leads to their transcriptional silencing. Survivin is directly regulated by STAT3. Stimulation of the parental MV4-11 cells with FLT3 ligand increases the expression of survivin and phosphorylated protein STAT1, STAT3, STAT5. Targeting survivin by short-hairpin RNA (shRNA) in MV4-11-R cells induces apoptosis and augments ABT-869–mediated cytotoxicity. Overexpression of survivin protects MV4-11 from apoptosis. Subtoxic dose of indirubin derivative (IDR) E804 resensitizes MV4-11-R to ABT-869 treatment by inhibiting STAT signaling activity and abolishing survivin expression. Combining IDR E804 with ABT-869 shows potent in vivo efficacy in the MV4-11-R xenograft model. Taken together, these results demonstrate that enhanced activation of STAT pathways and overexpression of survivin are important mechanisms of resistance to ABT-869, suggesting that the STAT pathways and survivin could be potential targets for reducing resistance developed in patients receiving FLT3 inhibitors.
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Haysen, S., A. L. L. Nielsen, P. Qvist, and T. W. Kragstrup. "POS0038 GENOMICS OF JAK-STAT SIGNALING IN VENOUS THROMBOEMBOLISM." Annals of the Rheumatic Diseases 81, Suppl 1 (May 23, 2022): 234.1–234. http://dx.doi.org/10.1136/annrheumdis-2022-eular.2593.
Abstract:
BackgroundJanus kinase inhibitors (JAKi) have been associated with an increased risk of venous thromboembolism (VTE) [1]. VTE comprises deep vein thrombosis and pulmonary embolism and is associated with complications such as recurrent VTE, post thrombotic syndrome, pulmonary hypertension, and death. These concerns limit the use of JAKi-based therapy. To improve risk stratification and drug development, it is crucial to understand the possible implication of dysregulated JAK-signal transducers and activators of transcription (STAT) signaling in the pathogenesis of VTE.ObjectivesThe objective of this study is to clarify the putative genomic vulnerability to dysregulated JAK-STAT signaling in VTE.MethodsWe are systematically mine and analyze large-scale genomic datasets generated from studies comparing VTE patients with healthy controls. Using VTE genome-wide associated (GWA) summary statistics we evaluate the representation of genes encoding the JAK-STAT pathway (KEGG hsa04630) in associated loci and assess their association to VTE. Further, we examine the genetic VTE risk burden in the chromatin interactome of STAT family transcription factors (TFs). We extract available STAT family (STAT1-3) TF binding site (TFBS) consensus DNA motifs (JASPAR database) and assess the association of genes containing STAT family TFBS within their promotor sequence (TSS -2000bp) to VTE. Through mining of deposited OMICs data from VTE patients, we examine molecular characteristics related to JAK-STAT signaling, including potential enrichment of STAT family TFBSs among query promoter sequences of differently expressed genes (DEGs).ResultsWe do not observe a significant overrepresentation of JAK-STAT genes (ntotal=162) among genes annotated to VTE significant GWA loci (ntotal=147, p=0.48). Similarly, the JAK-STAT gene set show no cumulative association to VTE (p=0.98). Applying the same gene set association approach to the STAT target gene sets (ntotal=4570) does not reveal significant association between VTE and STAT1 (noverlap=10, p=0.47), STAT1:STAT2 heterodimer (noverlap=18, p=0.17) and STAT3 (noverlap=6, p=0.20) target gene sets. At the functional molecular level, we do not see any significant overlap between molecules acting in the JAK-STAT pathway and DEGs (ntotal=507, p=0.06) or differentially abundant proteins (DAPs; ntotal=35, p=0.57). However, we observe a significant overlap between downregulated DEGs (ntotal=362) and the STAT1:STAT2 heterodimer target gene set (ntotal= 2155, noverlap=48, p<0.0001) including downregulation of IL-27RA and CCND3 (Figure 1). Supporting the biological relevance of this finding, we find a weak but statistically significant enrichment of STAT1 TFBS motifs in the promotor sequence of downregulated DEGs compared to non-DEGs (p=0.02).Figure 1.Overlap between STAT1:STAT2 heterodimer gene set and differently expressed genes (DEGs) in venous thromboembolism (VTE)ConclusionHere, we provide a coherent approach to assess the genomic basis for the reported association between JAKi treatment and VTE. Our preliminary data suggest that genes under transcriptional control of STAT family TFs may be dysregulated in VTE patients. It is conceivable, that the genomic actions of JAKi is overlapping with the molecular risk profile of VTE. CCND3 is especially interesting because VTE occurs in up to 10% of patients treated with cyclin-dependent kinase inhibitors such as Palbociclib [2]. Obviously, genomic data mining alone cannot guide medical decision making concerning the use of JAKi. However, our results provide a basis for further investigation of adverse events seen with JAKi.References[1]Charles-Schoeman, C., et al., The Risk of Venous Thromboembolic Events in Patients with RA Aged ≥ 50 Years with ≥ 1 Cardiovascular Risk Factor: Results from a Phase 3b/4 Randomized Safety Study of Tofacitinib vs TNF Inhibitors. Arthritis Rheumatol, 2021; 73 (suppl 10).[2]West, M.T., et al., CDK 4/6 inhibitors are associated with a high incidence of thrombotic events in women with breast cancer in real-world practice. Eur J Haematol, 2021. 106(5): p. 634-642.Disclosure of InterestsStine Haysen: None declared, Ane Langkilde-Lauesen Nielsen: None declared, Per Qvist: None declared, Tue Wenzel Kragstrup Speakers bureau: Speaking fees from Pfizer, Bristol-Myers Squibb, Eli Lilly, Novartis, UCB, and Abbvie., Consultant of: Consultancy fees from Bristol-Myers Squibb and Gilead., Grant/research support from: Research grants from Gilead., Employee of: Co-founder and clinical developer in iBio tech ApS.
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Zhang, Xuekang, Jun Zhou, Qian Hu, Zhengren Liu, Qiuhong Chen, Wenxiang Wang, Huaigen Zhang, Qin Zhang, and Yuanlu Huang. "The Role of Janus Kinase/Signal Transducer and Activator of Transcription Signalling on Preventing Intestinal Ischemia/Reperfusion Injury with Dexmedetomidine." Journal of Nanoscience and Nanotechnology 20, no. 5 (May 1, 2020): 3295–302. http://dx.doi.org/10.1166/jnn.2020.16416.
Abstract:
Dexmedetomidine (Dex) works as a crucial agent for the treatment of intestinal ischemia/reperfusion (I/R), but its mechanism remains unclear. Recent articles demonstrated the pivotal role of Janus kinase/signal transducer and activator of transcription (JAK2/STAT3) signalling in I/R. Therefore, it is reasonable to explore the associated mechanism of JAK2/STAT3 signalling in Dex treatment. The study purpose was to evaluate the JAK2/STAT3 signalling regulatory mechanisms of Dex in preventing I/R. Anaesthetized rats were subjected to superior mesenteric artery occlusion consisting of 1 h of ischemia and 2 h of reperfusion while served as controls. Animals received subcutaneous administration of 50 μg/kg Dex, JAK1 and JAK2 inhibitor, Ruxolitinib, selective JAK2 inhibitor, 10 mg/kg AG490 or STAT inhibitor and 0.4 mg/kg rapamycin; or Dex-treatment in the presence of α2-adrenoceptor antagonists Atip or Dex-treatment alone after I/R. Injury was scored histologically, apoptosis was detected via the apoptotic mediators caspase-3 and Bcl-2/Bax and the degree of activation of the JAK/STAT pathway was evaluated. Dex inhibited I/R injury by decreasing apoptosis significantly with rescue of cleaved caspase-3 and the Bcl-2/Bax ratio. Furthermore, phosphorylation of JAK2, STAT1 and STAT3 was affected, suggesting the involvement of activated JAK/STAT in response to Dex. Meanwhile, the JAK2 or STAT inhibitors AG490 and rapamycin, but not Ruxolitinib, exhibited a similar but even greater JAK2 and STAT3 regulatory effect, thus leading to a greater benefit. JAK2/STAT3 activation is crucial to the diminishing effect of Dex on mesenteric I/R injury; however, the efficacy and timing of Dex administration should be considered in clinical practice.
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Moser, Bernhard, Sophie Edtmayer, Agnieszka Witalisz-Siepracka, and Dagmar Stoiber. "The Ups and Downs of STAT Inhibition in Acute Myeloid Leukemia." Biomedicines 9, no. 8 (August 19, 2021): 1051. http://dx.doi.org/10.3390/biomedicines9081051.
Abstract:
Aberrant Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling is implicated in the pathogenesis of acute myeloid leukemia (AML), a highly heterogeneous hematopoietic malignancy. The management of AML is complex and despite impressive efforts into better understanding its underlying molecular mechanisms, survival rates in the elderly have not shown a substantial improvement over the past decades. This is particularly due to the heterogeneity of AML and the need for personalized approaches. Due to the crucial role of the deregulated JAK-STAT signaling in AML, selective targeting of the JAK-STAT pathway, particularly constitutively activated STAT3 and STAT5 and their associated upstream JAKs, is of great interest. This strategy has shown promising results in vitro and in vivo with several compounds having reached clinical trials. Here, we summarize recent FDA approvals and current potential clinically relevant inhibitors for AML patients targeting JAK and STAT proteins. This review underlines the need for detailed cytogenetic analysis and additional assessment of JAK-STAT pathway activation. It highlights the ongoing development of new JAK-STAT inhibitors with better disease specificity, which opens up new avenues for improved disease management.
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Brachet-Botineau, Marie, Marion Polomski, Heidi A. Neubauer, Ludovic Juen, Damien Hédou, Marie-Claude Viaud-Massuard, Gildas Prié, and Fabrice Gouilleux. "Pharmacological Inhibition of Oncogenic STAT3 and STAT5 Signaling in Hematopoietic Cancers." Cancers 12, no. 1 (January 18, 2020): 240. http://dx.doi.org/10.3390/cancers12010240.
Abstract:
Signal Transducer and Activator of Transcription (STAT) 3 and 5 are important effectors of cellular transformation, and aberrant STAT3 and STAT5 signaling have been demonstrated in hematopoietic cancers. STAT3 and STAT5 are common targets for different tyrosine kinase oncogenes (TKOs). In addition, STAT3 and STAT5 proteins were shown to contain activating mutations in some rare but aggressive leukemias/lymphomas. Both proteins also contribute to drug resistance in hematopoietic malignancies and are now well recognized as major targets in cancer treatment. The development of inhibitors targeting STAT3 and STAT5 has been the subject of intense investigations during the last decade. This review summarizes the current knowledge of oncogenic STAT3 and STAT5 functions in hematopoietic cancers as well as advances in preclinical and clinical development of pharmacological inhibitors.
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Kitanaga, Yukihiro, Emiko Imamura, Yutaka Nakahara, Hidehiko Fukahori, Yasutomo Fujii, Satoshi Kubo, Shingo Nakayamada, and Yoshiya Tanaka. "In vitro pharmacological effects of peficitinib on lymphocyte activation: a potential treatment for systemic sclerosis with JAK inhibitors." Rheumatology 59, no. 8 (November 25, 2019): 1957–68. http://dx.doi.org/10.1093/rheumatology/kez526.
Abstract:
Abstract Objectives Peficitinib, a novel Janus kinase (JAK) inhibitor, demonstrated promising results in treating RA in phase 3 clinical trials. This in vitro study was undertaken to characterize the pharmacological properties of peficitinib and investigate the involvement of JAK and signal transducer and activator of transcription (STAT) pathways in the pathological processes of SSc, which is also an autoimmune disease. Methods Phosphorylation levels of STAT molecules were assessed in peripheral blood mononuclear cells collected from patients with RA or SSc and healthy subjects, and in skin specimens obtained from 19 patients with SSc. In vitro inhibition of STAT phosphorylation and cytokine/chemokine production by peficitinib, tofacitinib and baricitinib were also characterized. Results Higher spontaneous STAT1 or STAT3 phosphorylation was observed in peripheral T-cells and monocytes from patients with RA and SSc compared with healthy subjects. In skin sections from patients with SSc, phosphorylated STAT3–positive cells were found in almost all cases, irrespective of disease subtype or patient characteristics. Conversely, phosphorylated STAT1-positive cells were observed only in samples from untreated patients with diffuse disease of short duration. Peficitinib inhibited STAT phosphorylation induced by various cytokines, with comparable efficacy to tofacitinib and baricitinib. Peficitinib also suppressed cytokine and chemokine production by peripheral blood mononuclear cells and skin fibroblasts. Conclusion Our results suggest that JAK/STAT pathways are constitutively activated in SSc and RA, and that the JAK inhibitor may represent a novel therapeutic option for SSc.
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Rodman, Esther, Michael Emch, Elizabeth Bruinsma, Xiaonan Hou, Scott Kaufmann, Saravut J. Weroha, and John Hawse. "Abstract 4862: Investigation of the JAK/STAT signaling pathway in chemotherapy and PARP inhibitor resistant ovarian cancer." Cancer Research 83, no. 7_Supplement (April 4, 2023): 4862. http://dx.doi.org/10.1158/1538-7445.am2023-4862.
Abstract:
Abstract Ovarian cancer is the 7th most common cancer in women and the most fatal of all female reproductive cancers, with 5-year overall survival of 10-30%. Despite initial responses to first line platinum- and paclitaxel-based chemotherapies, >70% of ovarian cancers recur with increasingly resistant disease; and nearly all of these women die of their disease. Recently, the use of targeted therapies such as bevacizumab and PARP inhibitors have been shown to improve progression-free survival in a subset of patients. However, these agents have thus far failed to improve overall survival in patients without specific genetic signatures, highlighting the continued need for alternative therapies. Through an unbiased drug screen, we have identified lestaurtinib as a potent inhibitor of many sensitive and resistant ovarian cancer cell lines and patient derived organoid models. Lestaurtinib is a known tyrosine kinase inhibitor originally developed to block FLT3, a protein that is not expressed in any of the ovarian cancer cell lines tested. To elucidate the mechanisms by which lestaurtinib inhibits ovarian cancer cells, we have examined its impact on the phospho-proteome in parallel with RNAseq. Results of these studied have identified inhibition of the JAK/STAT signaling pathway as a top hit. Assessment of STAT1 and STAT3 has revealed that these transcription factors are constitutively activated in chemotherapy- and PARP inhibitor-resistant cell lines as reflected by high levels of Tyr701/705 and Ser727 phosphorylation, suggesting that induction of this pathway may drive resistance. Surprisingly, profound differences in the ability of various JAK/STAT inhibitors to block these specific phosphorylation events is observed, which correlates with their potency. Further, STAT1 and STAT3 ChIPseq experiments following cytokine-mediated activation of this pathway reveal that these transcription factors bind to genomic regions encoding genes involved in oncogenic and drug resistance pathways. Genetic knockdown of STAT1 and STAT3 via siRNA, or knockout via CRISPR/Cas9, results in significant growth inhibition of sensitive and resistant models of ovarian cancer, confirming their importance in maintaining cell viability. Finally, combining lestuartinib with standard-of-care cisplatin or olaparib (a PARP inhibitor) is shown to be synergistic, indicating that pharmacological inhibition of JAK/STAT signaling has the potential to counteract drug resistance. Ongoing studies are aimed at further understanding the role of JAK/STAT signaling in ovarian cancer, elucidating the mechanistic processes by which STAT1/3 mediate progression of this disease, and identifying the most effective pharmacological strategies to study in possible future clinical trials. Citation Format: Esther Rodman, Michael Emch, Elizabeth Bruinsma, Xiaonan Hou, Scott Kaufmann, Saravut J. Weroha, John Hawse. Investigation of the JAK/STAT signaling pathway in chemotherapy and PARP inhibitor resistant ovarian cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4862.
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Rodman, Esther, Michael Emch, Archit Bajaj, Xiaojia Tang, Xiaonan Hou, Scott Kaufmann, Krishna Kalari, John Weroha, and John Hawse. "Abstract B002: Exploiting JAK/STAT signaling to inhibit highly advanced and resistant forms of ovarian cancer." Cancer Research 84, no. 5_Supplement_2 (March 4, 2024): B002. http://dx.doi.org/10.1158/1538-7445.ovarian23-b002.
Abstract:
Abstract Ovarian cancer is the most fatal of all female reproductive cancers due to its late detection, aggressive nature, and propensity to develop resistance to current standards of care. Despite initial responses to first line platinum- and paclitaxel-based chemotherapies, >70% of ovarian cancers recur with increasingly resistant disease. Targeted therapies, including PARP-inhibitors (PARPi) and VEGF-inhibitors, are being included in the front-line setting; and while they have improved progression-free survival in a subset of patients, they have thus far failed to improve overall survival in patients without specific genetic signatures. With the broad uptake of PARPi, PARPi-resistance is becoming common. Once resistance develops, nearly all patients die of their disease and there is an obvious need to elucidate the basis for chemotherapy- and PARPi-resistance and devise novel approaches to overcome resistance. Using a small molecule drug screen, we identified lestaurtinib, a known tyrosine kinase inhibitor as a potent inhibitor of treatment naive and highly advanced models of ovarian cancer. Lestaurtinib was originally developed to target FLT3, a protein not expressed in any ovarian cancer models we’ve tested. To identify lestaurtinib targets, we preformed phospho-proteomics in parallel with RNAseq and discovered the JAK/STAT signally pathway as a top hit. We confirmed that essential components of JAK/STAT signaling are constitutively activated in chemotherapy- and PARPi-resistant cells, suggesting that induction of this pathway may drive resistance. Importantly, we found that lestaurtinib-sensitive patient-derived-xenografts (PDXs) exhibited higher expression of multiple JAK/STAT signaling pathway members compared to PDXs that did not respond to lestaurtinib. Genetic knockdown of STAT1 and STAT3 via siRNA, or knockout via CRISPR/Cas9, resulted in significant growth inhibition of sensitive and resistant models, confirming their importance in maintaining cell viability and progression. Combining lestuartinib with standard-of-care cisplatin or olaparib, a PARPi, was shown to be synergistic in multiple models, indicating that pharmacological inhibition of JAK/STAT signaling has the potential to alleviate drug resistance. Finally, we assessed a panel of JAK/STAT inhibitors that interfere at various levels of the pathway and found profound differences in their ability to block STAT-phosphorylation and inhibit cell proliferation. Thus, it is critical to further define the mechanisms by which these drugs function to selectively suppress JAK/STAT signaling in order to elucidate specific nodes of the pathway that drive ovarian cancer progression. Ongoing studies are aimed at identifying the unique roles of STAT1 and STAT3, the specific contributions of their tyrosine and serine phosphorylation, and the relevance of up-/down-stream mediators of the JAK/STAT pathway on ovarian cancer cell growth with the goal of informing future clinical trials. Citation Format: Esther Rodman, Michael Emch, Archit Bajaj, Xiaojia Tang, Xiaonan Hou, Scott Kaufmann, Krishna Kalari, John Weroha, John Hawse. Exploiting JAK/STAT signaling to inhibit highly advanced and resistant forms of ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B002.
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Liang, Zengenni, Zhi-Hang Yuan, Yan Wang, Zhong-Hua Du, Jia-Jing Guo, Ling-Li Xia, and Yang Shan. "New Mechanistic Insight into the Protective Effects of Ganoderma lucidum Polysaccharides Against Palmitic Acid-Induced Cell Damage in Porcine Intestinal Epithelial Cell Line IPEC-J2." Natural Product Communications 17, no. 11 (November 2022): 1934578X2211281. http://dx.doi.org/10.1177/1934578x221128103.
Abstract:
Ganoderma lucidum ( G. lucidum) is one of the well-known mushrooms in China, which has G. lucidum polysaccharides (GLP) that have been widely studied for various biological activities, such as antioxidant, antitumor, antiinflammatory, antiviral, antidiabetes, and immunomodulatory activities. A signal transducer and activator of transcription (STAT) signaling pathway is related to cell proliferation and apoptosis. The relationship between STAT and intestinal protection of GLP is still unknown. We studied the inhibitors AG490 in the STAT pathway and its downstream molecules to analyze the unique effects in the protection of GLP against palmitic acid (PA)-induced porcine intestinal epithelial cells (IPEC-J2) injury. Compared to PA treatment, GLP + PA obviously decreased Ca2+ concentration, H2O2 production, NF-E2-related factor 2 (Nrf2) nuclear translocation, STAT1 and STAT2 protein levels, and increased nuclear factor kappa-B (NF-κB) nuclear translocation and p-STAT3/STAT3 ratio in IPEC-J2 cells. After inhibition of STAT3 signaling, p-STAT3/STAT3 ratio, NF-κB nuclear translocation obviously decreased and Nrf2 nuclear translocation significantly increased in the GLP + PA group. The protection of GLP on proliferation and apoptosis of PA-induced IPEC-J2 cells was suppressed by inhibiting STAT3. The STAT3 pathway regulated the enterocyte-protective effects of GLP by modulating the nuclear translocation of Nrf2 and NF-κB. We provide new insights into the mechanism of STAT signaling for the protection of GLP on PA-induced intestinal epithelial cell injury.
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Komyod, Waraporn, Uta-Maria Bauer, Peter C. Heinrich, Serge Haan, and Iris Behrmann. "Are STATS Arginine-methylated?" Journal of Biological Chemistry 280, no. 23 (April 12, 2005): 21700–21705. http://dx.doi.org/10.1074/jbc.c400606200.
Abstract:
Transcription factors of the STAT (signal transducer and activator of transcription) family are important in signal transduction of cytokines. They are subject to post-translational modification by phosphorylation on tyrosine and serine residues. Recent evidence suggested that STATs are methylated on a conserved arginine residue within the N-terminal region. STAT arginine methylation has been described to be important for STAT function and loss of arginine methylation was discussed to be involved in interferon resistance of cancer cells. Here we provide several independent lines of evidence indicating that the issue of arginine methylation of STATs has to be reassessed. First, we show that treatment of melanoma and fibrosarcoma cells with inhibitors used to suppress methylation (N-methyl-2-deoxyadenosine, adenosine, dl-homocysteine) had profound and rapid effects on phosphorylation of STAT1 and STAT3 but also on p38 and Erk signaling cascades which are known to cross-talk with the Jak/STAT pathway. Second, we show that anti-methylarginine antibodies did not precipitate specifically STAT1 or STAT3. Third, we show that mutation of Arg31 to Lys led to destabilization of STAT1 and STAT3, implicating an important structural role of Arg31. Finally, purified catalytically active protein arginine methyltransferases (PRMT1, -2, -3, -4, and -6) did not methylate STAT proteins, and cotransfection with PRMT1 did not affect STAT1-controlled reporter gene activity. Taken together, our data suggest the absence of arginine methylation of STAT1 and STAT3.
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Callus, Bernard A., and Bernard Mathey-Prevot. "Interleukin-3–Induced Activation of the JAK/STAT Pathway Is Prolonged by Proteasome Inhibitors." Blood 91, no. 9 (May 1, 1998): 3182–92. http://dx.doi.org/10.1182/blood.v91.9.3182.
Abstract:
Abstract One facet of cytokine receptor signaling involves the activation of signal transducers and activators of transcription (STATs). STATs are rapidly activated via tyrosine phosphorylation by Janus kinase (JAK) family members and subsequently inactivated within a short period. We investigated the effect of proteasome inhibition on interleukin-3 (IL-3) activation of the JAK/STAT pathway following stimulation of Ba/F3 cells. Treatment of Ba/F3 cells with the proteasome inhibitor,N-acetyl-l-leucinyl-l-leucinyl-norleucinal (LLnL), led to stable tyrosine phosphorylation of the IL-3 receptor, beta common (βc), and STAT5 following stimulation. The effects of LLnL were not restricted to the JAK/STAT pathway, as Shc and mitogen-activated protein kinase (MAPK) phosphorylation were also prolonged in LLnL-treated cells. Further investigation showed these stable phosphorylation events were the result of prolonged activation of JAK2 and JAK1. These observations were confirmed using pharmacologic inhibitors. In the presence of LLnL, stable phosphorylation of STAT5 and βc was abrogated if the tyrosine kinase inhibitor, staurosporine, was added. The effect of staurosporine on STAT5 phosphorylation could be overcome if the phosphatase inhibitor, vanadate, was also added, suggesting phosphorylated STAT5 could be stabilized by phosphatase, but not by proteasome inhibition per se. These observations are consistent with the hypothesis that proteasome-mediated protein degradation can modulate the activity of the JAK/STAT pathway by regulating the deactivation of JAK.
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Callus, Bernard A., and Bernard Mathey-Prevot. "Interleukin-3–Induced Activation of the JAK/STAT Pathway Is Prolonged by Proteasome Inhibitors." Blood 91, no. 9 (May 1, 1998): 3182–92. http://dx.doi.org/10.1182/blood.v91.9.3182.3182_3182_3192.
Abstract:
One facet of cytokine receptor signaling involves the activation of signal transducers and activators of transcription (STATs). STATs are rapidly activated via tyrosine phosphorylation by Janus kinase (JAK) family members and subsequently inactivated within a short period. We investigated the effect of proteasome inhibition on interleukin-3 (IL-3) activation of the JAK/STAT pathway following stimulation of Ba/F3 cells. Treatment of Ba/F3 cells with the proteasome inhibitor,N-acetyl-l-leucinyl-l-leucinyl-norleucinal (LLnL), led to stable tyrosine phosphorylation of the IL-3 receptor, beta common (βc), and STAT5 following stimulation. The effects of LLnL were not restricted to the JAK/STAT pathway, as Shc and mitogen-activated protein kinase (MAPK) phosphorylation were also prolonged in LLnL-treated cells. Further investigation showed these stable phosphorylation events were the result of prolonged activation of JAK2 and JAK1. These observations were confirmed using pharmacologic inhibitors. In the presence of LLnL, stable phosphorylation of STAT5 and βc was abrogated if the tyrosine kinase inhibitor, staurosporine, was added. The effect of staurosporine on STAT5 phosphorylation could be overcome if the phosphatase inhibitor, vanadate, was also added, suggesting phosphorylated STAT5 could be stabilized by phosphatase, but not by proteasome inhibition per se. These observations are consistent with the hypothesis that proteasome-mediated protein degradation can modulate the activity of the JAK/STAT pathway by regulating the deactivation of JAK.
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Kuusanmäki, Heikki, Hanna Rajala, Arjan van Adrichem, Muntasir Mamun Majumder, Emma I. Andersson, Krister Wennerberg, Satu Mustjoki, and Caroline A. Heckman. "Drug Sensitivity Profiling Identifies Drugs for Targeting Constitutively Active Mutant STAT3 and Mutant STAT5B Positive Malignancies." Blood 124, no. 21 (December 6, 2014): 1771. http://dx.doi.org/10.1182/blood.v124.21.1771.1771.
Abstract:
Abstract Introduction: Constitutive hyperactivation of the STAT3 and STAT5B transcription factors is often observed in cancer. Lately, activating STAT3 mutations have been identified in hematological malignancies including large granular lymphocytic (LGL) leukemia (prevalence 40%), aplastic anemia (7%) and CD30+ T-cell lymphoma (17%). Furthermore, recent studies highlight the importance of STAT5B mutations in the pathogenesis and prognosis of T-cell malignancies such as T-cell prolymphocytic leukemia (36%), T-cell acute lymphoblastic leukemia (8%) and hepatosplenic T-cell lymphoma (33%). While STAT3 and STAT5B mutations lead to constitutive STAT3/STAT5B signaling, several other known gene mutations and mechanisms may also cause JAK/STAT-pathway activation. These findings indicate that inhibiting the JAK/STAT pathway with targeted drugs could be used as a treatment option. Here, we aimed to identify drugs that inhibit STAT3 or STAT5B function and determine if mutant STAT3/5B and wild type STAT3/5B cells respond differently to the tested drugs. In addition, we wished to ascertain if STAT3 inhibition is sufficient to induce apoptosis in patient derived LGL cells with constitutively active STAT3. Methods: High-throughput drug sensitivity testing was performed with a compound collection containing over 300 approved and investigational oncology drugs including many kinase inhibitors (such as those targeting JAK, SRC, VEGFR, mTOR, MEK, and CHK) and small molecule STAT3 inhibitors (Stattic, LLL12, Sta-21). All drugs were tested in 5-8 different concentrations over a 10,000-fold concentration range. Mutant STAT3 (Y640F) and mutant STAT5B (N642H) transformed Ba/F3 cells as well as HEK293 cells containing a STAT5 (pGL4.52[luc2P/STAT5 RE/Hygro]) or STAT3 specific luciferase reporter gene element (HEK-SIE) were used in the screens. In addition, drug sensitivities of five LGL leukemia patient samples were also assessed. Primary patient cells and the Ba/F3 cells were incubated in 384-well plates for three days with the drugs after which cell viability was measured with CellTiter-Glo. STAT3/5B induced luciferase activity in the HEK cells was analyzed after the cells were incubated for 6 or 24 hours with the drugs using the ONE-Glo luciferase assay system. Results: A significant decrease in luciferase activity was detected in STAT3 mutant Y640F, STAT5B mutant N642H and wild type STAT3 transfected HEK-SIE cells in the presence of PI3K/mTOR inhibitors such as PF-04691502 and INK128. In addition, PI3K/mTOR inhibitors significantly decreased the viability of mutant STAT3 and STAT5B transformed Ba/F3 cells compared to wild type cells. Interestingly, JAK inhibitors (e.g. ruxolitinib, gandotinib) did not inhibit mutant STAT3 activity in the HEK-SIE cells, whereas IL6-induced wild type STAT3 activity was completely blocked. A BET family inhibitor (JQ1+) and glucocorticoids (e.g. dexamethasone, methylprednisolone) showed specific and strong cytotoxicity to mutant STAT3 and STAT5B transformed Ba/F3 cells. Although JQ1+ inhibited luciferase activity of STAT5B N642H cells, no effect on the luciferase activity of STAT3 Y640F transfected HEK cells was detected, suggesting that JQ1+ may have a direct effect on mutant STAT5B function while the effect on mutant STAT3 transformed cells may be indirect. Cells from LGL leukemia patients showed high sensitivity against glucocorticoids, the histone deacetylase inhibitor quisinostat, JQ1+ and PF-04691502 when compared to healthy CD8+ T-cells. However, no increase in apoptosis was observed with JAK or other mTOR inhibitors. Conclusions: Our results suggest that JAK inhibitors lack efficacy in STAT3 mutated diseases. However, our ex vivo and in vitro drug screens highlight some other promising agents including PF-04691502 (PI3K/mTOR inhibitor) and JQ1+ (BET family inhibitor) that inhibited mutant STAT5B and STAT3 activity in the cell line models and were effective against primary LGL patient cells. Additional experiments are ongoing to determine how these drugs function to block STAT signaling and induce cell death. As the STAT3 and STAT5 pathways are activated in many other cancer types as well, the results may be applicable to a variety of different malignancies. Figure 1 Figure 1. Table 1. Drug sensitivity scores of the different cell line models and patient samples. DSS value range 0-50. (0 = no drug response with any conc., 50 = maximal drug response with every conc.) Disclosures Mustjoki: Bristol-Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria, Research Funding.
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Ozawa, Yukiyasu, Ann H. Williams, Myka Estes, Lubomir Sokol, Richard Jove, and Alan F. List. "Regulation of Signal Transducers and Activators of Transcription by Src Family Kinase in AML." Blood 106, no. 11 (November 16, 2005): 2766. http://dx.doi.org/10.1182/blood.v106.11.2766.2766.
Abstract:
Abstract Specific Signal Transducers and Activators of Transcription (STAT) family members are constitutively activated in leukemia where they contribute to leukemia self-renewal and apoptosis resistance. STAT5 activation in chronic myeloid leukemia (CML) is driven by the Bcr-Abl and Lyn kinases, whereas in acute myelogenous leukemia (AML), STAT5 and STAT3 activation is demonstrable under the control of as yet undefined upstream regulators. To investigate the regulation of STAT activation in AML, we evaluated the role of Src family kinases in AML cell lines and primary patient specimens. Inhibition of leukemia cell prolifaration by Src inhibitors was evaluated in 7 cell lines (U937, HEL, KG-1a, THP-1, OCI-AML3, HL-60 and NB-4). Treatment with either PD180970 or SKI-606 significantly suppressed proliferation and decreased viability in a concentration-dependent manner in two cell lines. U937 cells displayed sensitivity comparable to K562 CML cells, whereas KG-1a cells demonstrated moderate inhibition. Corresponding DNA-STAT5 binding activity assessed by electrophoretic mobility shift assay (EMSA) showed constitutively STAT5 activation in 3 cell lines (U937, HEL and KG-1a), with inhibition of STAT5 DNA binding By Src inhibitors in U937 and KG-1a cells, while STAT5 activity was not impaired in HEL cells. STAT5 protein phosphorylation assessed by immunoblot was suppressed by the Src inhibitors in the sensitive cell lines. Moreover, Src inhibition decreased Bcl-XL expression, a transcriptional target of STAT5, and induced apoptosis in U937 cells. Immunoblot assessment of phosphorylation of the activation loop tyrosine in the two major src kinases, c-Src and Lyn, confirmed inhibition of autophosphorylation in U937 cells and K562 cells by PD180970 and SKI-606, while phosphorylation was unchanged in HEL cells. Inhibition of src kinases was rapid (< 30 min), and preceeded inhibition of STAT5 activation. Analysis of primary AML patient cells revealed that 29 % (5 of 17) of patient cells have constitutively-activated STAT5, and 47 % (8 of 17) have constitutively-activated STAT3. More importantly, some primary AML patient cells were sensitive to Src inhibitor. These data suggest that Src activation of STAT5 has a pathogenetic role in AML cells. Investigation of Src inhibitors merits clinical investigation in patients with AML.
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Song, Tammy Linlin, Maarja-Liisa Nairismägi, Yurike Laurensia, Jing-Quan Lim, Jing Tan, Zhi-Mei Li, Wan-Lu Pang, et al. "Oncogenic activation of the STAT3 pathway drives PD-L1 expression in natural killer/T-cell lymphoma." Blood 132, no. 11 (September 13, 2018): 1146–58. http://dx.doi.org/10.1182/blood-2018-01-829424.
Abstract:
Key Points Alterations in JAK/STAT signaling pathway are highly prevalent in PTCL and NKTL, where STAT3 and TP53 are the most frequently mutated genes. STAT3 activation drives PD-L1 expression in NKTL, providing a rationale to combine STAT3 inhibitors with immune checkpoint inhibitors.
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Jang, Sun Hee, and Ji Hyeon Ju. "Janus kinase inhibitors for the treatment of rheumatoid arthritis." Journal of the Korean Medical Association 64, no. 2 (February 10, 2021): 105–8. http://dx.doi.org/10.5124/jkma.2021.64.2.105.
Abstract:
Rheumatoid arthritis is a chronic inflammatory destructive disorder that affects the joints, muscles, and tendons accompanying various extra-articular manifestations. Traditional disease-modifying anti-rheumatic drugs (DMARDs) represent the basic treatment for rheumatoid arthritis. Over the last 20 years, biologic DMARDs (tumor necrosis factor inhibitors, interleukin-1 inhibitors, interleukin-6 inhibitors, T cell inhibitors, and B cell inhibitors) have been widely used as a novel class of DMARDs that have efficacy and efficiency. Discovery of the underlying pathogenesis of autoimmune disease enables us to develop new target therapies such as a Janus kinase (JAK) inhibitor. Activated JAK is known to activate signal transducers as well as activators of transcription (STAT) signaling. A JAK inhibitor is a type of medication that functions by inhibiting the JAK-STAT signaling pathway. In addition, it is easy to take a JAK inhibitor orally. In Korea, several JAK inhibitors have been approved. This review describes the types of JAK inhibitors, recommended doses, side effects, and updated European Alliance of Associations for Rheumatology guidelines. Clinicians should more often consider JAK inhibitors in the treatment of refractory rheumatoid arthritis in current rheumatology clinics
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Banes, Amy K., Séan Shaw, John Jenkins, Heather Redd, Farhad Amiri, David M. Pollock, and Mario B. Marrero. "Angiotensin II blockade prevents hyperglycemia-induced activation of JAK and STAT proteins in diabetic rat kidney glomeruli." American Journal of Physiology-Renal Physiology 286, no. 4 (April 2004): F653—F659. http://dx.doi.org/10.1152/ajprenal.00163.2003.
Abstract:
Clinical and animal studies show that treatment with angiotensin-converting enzyme (ACE) inhibitors or ANG II-receptor antagonists slows progression of nephropathy in diabetes, indicating ANG II plays an important role in its development. We previously reported that hyperglycemia augments both ANG II-induced growth and activation of Janus kinase (JAK)2 and signal transducers and activators of transcription (STAT) proteins in cultured rat mesangial cells. Furthermore, we demonstrated that the tyrosine kinase enzyme JAK2 plays a key role in both ANG II- and hyperglycemia-induced growth in these cells. We hypothesized that the ACE inhibitor captopril and the ANG II-receptor antagonist candesartan would hinder hyperglycemic-induced activation of JAK and STAT proteins in rat glomeruli, demonstrating that ANG II plays an important role in the activation of these proteins in vivo. Adult male Sprague-Dawley rats were given either streptozotocin (STZ; 60 mg/kg iv) or vehicle, and glomeruli were isolated 2 wk later. Activation of JAK and STAT proteins was evaluated by Western blot analysis for specific tyrosine phosphorylation. Groups of rats were given captopril (75–85 mg·kg-1·day-1), candesartan (10 mg· kg-1·day-1), or the JAK2 inhibitor AG-490 (5 mg·kg-1·day-1) for the study's duration. STZ stimulated glomerular phosphorylation of JAK2, STAT1, STAT3, and STAT5. Phosphorylation was reduced in rats treated with captopril, candesartan, and AG-490. Furthermore, both candesartan and AG-490 inhibited STZ-induced increases in urinary protein excretion. In conclusion, our studies demonstrate that hyperglycemia induces activation of JAK2 and the STATs in vivo via an ANG II-dependent mechanism and that these proteins may be involved in the early kidney damage associated with diabetes.
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Thomas, Sally J., Katherine Fisher, Stephen Brown, John A. Snowden, Sarah Danson, and Martin Zeidler. "Methotrexate Is a Suppressor of JAK/STAT Pathway Activation Which Inhibits JAK2V617F Induced Signalling." Blood 124, no. 21 (December 6, 2014): 4577. http://dx.doi.org/10.1182/blood.v124.21.4577.4577.
Abstract:
Abstract The classical myeloproliferative neoplasms (MPNs) are a group of disorders characterised by activation of the JAK/STAT signalling pathway. A large proportion of patients with MPNs have an acquired mutation, JAK2V617F, which causes constitutive kinase activity. Patients with wild-type JAK2 show gene expression patterns characteristic of JAK/STAT activation, and the majority have mutations in other genes associated with increased pathway activation. Inhibition of JAK/STAT activation represents an attractive therapeutic approach for these disorders. In myelofibrosis, treatment with a JAK inhibitor reduces spleen volume, improves quality of life and prolongs life expectancy, whereas there is evidence that other therapies are no better than placebo. This study aimed to find new treatments for MPNs by identifying compounds that suppress JAK/STAT activation. We screened a small-molecule library consisting of FDA approved drugs, cytotoxic drugs, agrochemicals, and pure natural products to identify modulators of STAT-responsive transcription in the low complexity Drosophila model. We independently identified methotrexate (z-score -8.72) and the chemically similar aminopterin (z-score -8.2) as strong inhibitors of Drosophila JAK/STAT activation. The suppression of transcriptional reporter activity was dose dependent and was observed following activation of the pathway with the Drosophila JAK/STAT ligand Upd and by the gain of function Drosophila JAK HopTuml. To examine whether these results translated to the more complex JAK/STAT signalling pathway of humans we examined the effect of methotrexate in the Hodgkin Lymphoma cell line HDLM-2, which shows constitutive phosphorylation of several JAK/STAT family members. Immunoblotting for phosphorylated pathway components showed that methotrexate produced a dose dependent reduction in levels of tyrosine phosphorylated STAT5 (Y694), without affecting total STAT5 levels. Methotrexate did not affect phosphorylated proteins in other signalling pathways, including pAKT, p c-Jun or pMAPK. To examine the potential of methotrexate as a treatment for MPNs, we used the HEL cell line, which is homozygous for JAK2V617F and shows STAT5 phosphorylation that is dependent on JAK2 activity. Immunoblotting showed that methotrexate produced a dose dependent reduction in levels of pSTAT5. Significant suppression of STAT5 phosphorylation was seen following treatment with methotrexate at concentrations equivalent to those measured in the serum of patients taking low dose oral methotrexate (0.4 – 0.8 mM, p<0.001, one-way ANOVA with Dunnett’s multiple comparisons test). Suppression of STAT5 phosphorylation persisted in the presence of folinic acid at concentrations used to prevent methotrexate toxicity, suggesting that the effect on JAK/STAT signalling is not mediated by impairment of folate metabolism. Methotrexate did not completely prevent signalling via the JAK/STAT pathway, as methotrexate-treated cells were still able to phosphorylate STAT5 following stimulation with the EpoR/JAK2/STAT5 pathway ligand erythropoietin. The reduction in STAT5 phosphorylation produced by treatment with methotrexate was comparable to that produced by the JAK1/JAK2 inhibitor ruxolitinib, although ruxolitinib was a more potent inhibitor of pathway activation. Given that methotrexate is used to treat inflammatory disorders and activation of JAK/STAT signalling is involved in the inflammatory response we examined the effect of methotrexate on rheumatoid arthritis fibroblast-like synoviocytes. Methotrexate also reduced constitutive STAT phosphorylation in these primary cells. Our results suggest that low-dose oral methotrexate should be investigated as a potential treatment for patients with MPNs. We suggest that methotrexate may suppress pathological over-activation of the JAK/STAT pathway sufficiently to control disease and bring about the benefits demonstrated with specific JAK inhibitors, without preventing physiological activation required for haematopoiesis and response to infection. Methotrexate is inexpensive and has advantages as a potential treatment as its safety and adverse effects are already well understood. Furthermore, our results suggest that suppression of JAK/STAT pathway activation may be a mechanism through which methotrexate exerts anti-inflammatory and immunosuppressive effects. Disclosures Off Label Use: Methotrexate is widely used as a chemotherapy drug and to treat inflammatory disorders. This work includes a discussion of the potential use of methotrexate to treat myeloproliferative neoplasms, based on experiments in cell lines.
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Severin, Frezzato, Visentin, Martini, Trimarco, Carraro, Tibaldi, et al. "In Chronic Lymphocytic Leukemia the JAK2/STAT3 Pathway Is Constitutively Activated and Its Inhibition Leads to CLL Cell Death Unaffected by the Protective Bone Marrow Microenvironment." Cancers 11, no. 12 (December 4, 2019): 1939. http://dx.doi.org/10.3390/cancers11121939.
Abstract:
The bone marrow microenvironment promotes proliferation and drug resistance in chronic lymphocytic leukemia (CLL). Although ibrutinib is active in CLL, it is rarely able to clear leukemic cells protected by bone marrow mesenchymal stromal cells (BMSCs) within the marrow niche. We investigated the modulation of JAK2/STAT3 pathway in CLL by BMSCs and its targeting with AG490 (JAK2 inhibitor) or Stattic (STAT3 inhibitor). B cells collected from controls and CLL patients, were treated with medium alone, ibrutinib, JAK/Signal Transducer and Activator of Transcription (STAT) inhibitors, or both drugs, in the presence of absence of BMSCs. JAK2/STAT3 axis was evaluated by western blotting, flow cytometry, and confocal microscopy. We demonstrated that STAT3 was phosphorylated in Tyr705 in the majority of CLL patients at basal condition, and increased following co-cultures with BMSCs or IL-6. Treatment with AG490, but not Stattic, caused STAT3 and Lyn dephosphorylation, through re-activation of SHP-1, and triggered CLL apoptosis even when leukemic cells were cultured on BMSC layers. Moreover, while BMSCs hamper ibrutinib activity, the combination of ibrutinib+JAK/STAT inhibitors increase ibrutinib-mediated leukemic cell death, bypassing the pro-survival stimuli derived from BMSCs. We herein provide evidence that JAK2/STAT3 signaling might play a key role in the regulation of CLL-BMSC interactions and its inhibition enhances ibrutinib, counteracting the bone marrow niche.
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LEJEUNE, Diane, Jean-Baptiste DEMOULIN, and Jean-Christophe RENAULD. "Interleukin 9 induces expression of three cytokine signal inhibitors: cytokine-inducible SH2-containing protein, suppressor of cytokine signalling (SOCS)-2 and SOCS-3, but only SOCS-3 overexpression suppresses interleukin 9 signalling." Biochemical Journal 353, no. 1 (December 18, 2000): 109–16. http://dx.doi.org/10.1042/bj3530109.
Abstract:
Interleukin 9 (IL-9) is a cytokine preferentially produced by T helper type 2 lymphocytes and active on various cell types such as T- and B-lymphocytes, mast cells and haemopoietic progenitors. The IL-9 receptor (IL-9R) belongs to the haemopoietic receptor superfamily and its signal transduction involves mainly the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. Here we studied the implication of a novel family of suppressors of cytokine signalling (called CIS, for cytokine-inducible SH2-containing protein, and SOCS, for suppressor of cytokine signalling) in IL-9 signal attenuation. In BW5147 T-cell lymphoma, IL-9 induced the rapid expression of CIS, SOCS-2 and SOCS-3 with a peak after 2h of stimulation. Using IL-9R mutants, we showed that STAT activation is required for CIS/SOCS induction: CIS and SOCS-2 expression was induced either via STAT1 and/or STAT3 or via STAT5 but only STAT1 and/or STAT3 were involved in SOCS-3 expression. The effect of these three proteins on IL-9 signal transduction was assessed by transient transfection in HEK-293 cells expressing the components of the IL-9 signalling pathway and a STAT-responsive reporter construct. These experiments showed that only SOCS-3 is able to inhibit IL-9-induced signal transduction; neither CIS nor SOCS-2 exerted any effect. Stable transfection of CIS and SOCS-3 in BW5147 lymphoma cells showed that only overexpression of SOCS-3 had an inhibitory activity on STAT activation, gene induction and the anti-apoptotic activity of IL-9. By contrast, CIS failed to affect the IL-9 response.
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Malemud, Charles J. "The role of the JAK/STAT signal pathway in rheumatoid arthritis." Therapeutic Advances in Musculoskeletal Disease 10, no. 5-6 (May 19, 2018): 117–27. http://dx.doi.org/10.1177/1759720x18776224.
Abstract:
Proinflammatory cytokine activation of the Janus kinase/signal transducers and activators of transcription (JAK/STAT) signal transduction pathway is a critical event in the pathogenesis and progression of rheumatoid arthritis. Under normal conditions, JAK/STAT signaling reflects the influence of negative regulators of JAK/STAT, exemplified by the suppressor of cytokine signaling and protein inhibitor of activated STAT. However, in rheumatoid arthritis (RA) both of these regulators are dysfunctional. Thus, continuous activation of JAK/STAT signaling in RA synovial joints results in the elevated level of matrix metalloproteinase gene expression, increased frequency of apoptotic chondrocytes and most prominently ‘apoptosis resistance’ in the inflamed synovial tissue. Tofacitinib, a JAK small molecule inhibitor, with selectivity for JAK2/JAK3 was approved by the United States Food and Drug Administration (US FDA) for the therapy of RA. Importantly, tofacitinib has demonstrated significant clinical efficacy for RA in the post-US FDA-approval surveillance period. Of note, the success of tofacitinib has spurred the development of JAK1, JAK2 and other JAK3-selective small molecule inhibitors, some of which have also entered the clinical setting, whereas other JAK inhibitors are currently being evaluated in RA clinical trials.
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Hindupur, Sruthi V., Sebastian C. Schmid, Jana Annika Koch, Ahmed Youssef, Eva-Maria Baur, Dongbiao Wang, Thomas Horn, et al. "STAT3/5 Inhibitors Suppress Proliferation in Bladder Cancer and Enhance Oncolytic Adenovirus Therapy." International Journal of Molecular Sciences 21, no. 3 (February 7, 2020): 1106. http://dx.doi.org/10.3390/ijms21031106.
Abstract:
The JAK-STAT signalling pathway regulates cellular processes like cell division, cell death and immune regulation. Dysregulation has been identified in solid tumours and STAT3 activation is a marker for poor outcome. The aim of this study was to explore potential therapeutic strategies by targeting this pathway in bladder cancer (BC). High STAT3 expression was detected in 51.3% from 149 patient specimens with invasive bladder cancer by immunohistochemistry. Protein expression of JAK, STAT and downstream targets were confirmed in 10 cell lines. Effects of the JAK inhibitors Ruxolitinib and BSK-805, and STAT3/5 inhibitors Stattic, Nifuroxazide and SH-4-54 were analysed by cell viability assays, immunoblotting, apoptosis and cell cycle progression. Treatment with STAT3/5 but not JAK1/2 inhibitors reduced survival, levels of phosphorylated STAT3 and Cyclin-D1 and increased apoptosis. Tumour xenografts, using the chicken chorioallantoic membrane (CAM) model responded to Stattic monotherapy. Combination of Stattic with Cisplatin, Docetaxel, Gemcitabine, Paclitaxel and CDK4/6 inhibitors showed additive effects. The combination of Stattic with the oncolytic adenovirus XVir-N-31 increased viral replication and cell lysis. Our results provide evidence that inhibitors against STAT3/5 are promising as novel mono- and combination therapy in bladder cancer.
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Jeong, Ga Hee, and Ji Hyun Lee. "Dysregulated Hippo Signaling Pathway and YAP Activation in Atopic Dermatitis: Insights from Clinical and Animal Studies." International Journal of Molecular Sciences 24, no. 24 (December 10, 2023): 17322. http://dx.doi.org/10.3390/ijms242417322.
Abstract:
The yes-associated protein (YAP) of the Hippo pathway regulates a variety of target genes involved in cell proliferation, survival, and inflammation. YAP and transcription activator with a PDZ-binding motif (TAZ) proteins act as mediators of the inflammatory response. Still, their role in atopic dermatitis (AD)—particularly, the association with the nuclear factor kappa-B and Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathways—is not fully understood. In this study, we found that YAP, is upregulated in AD patients and NC/Nga mouse model of AD. In addition, inhibition of YAP significantly reduced epidermal cell proliferation by 58% and mast cell numbers by 51% and attenuated the upregulation of both Th1- and Th2-associated cytokines. Among the JAK-STAT family proteins, the expressions of JAK1 and JAK2 and those of STAT1, STAT2, and STAT3 were also downregulated. These findings may explain the role of YAP in AD and suggest YAP inhibitors as promising therapeutic agents for AD.
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Kim, Lee, Song, Park, Gadhe, Choi, Lee, Pae, Kim, and Ye. "Development of Oxadiazole-Based ODZ10117 as a Small-Molecule Inhibitor of STAT3 for Targeted Cancer Therapy." Journal of Clinical Medicine 8, no. 11 (November 2, 2019): 1847. http://dx.doi.org/10.3390/jcm8111847.
Abstract:
Persistently activated STAT3 is a promising target for a new class of anticancer drug development and cancer therapy, as it is associated with tumor initiation, progression, malignancy, drug resistance, cancer stem cell properties, and recurrence. Here, we discovered 3-(2,4-dichloro-phenoxymethyl)-5-trichloromethyl-[1,2,4]oxadiazole (ODZ10117) as a small-molecule inhibitor of STAT3 to be used in STAT3-targeted cancer therapy. ODZ10117 targeted the SH2 domain of STAT3 regardless of other STAT family proteins and upstream regulators of STAT3, leading to inhibition of the tyrosine phosphorylation, dimerization, nuclear translocation, and transcriptional activity of STAT3. The inhibitory effect of ODZ10117 on STAT3 was stronger than the known STAT3 inhibitors such as S3I-201, STA-21, and nifuroxazide. ODZ10117 suppressed the migration and invasion, induced apoptosis, reduced tumor growth and lung metastasis, and extended the survival rate in both in vitro and in vivo models of breast cancer. Overall, we demonstrated that ODZ10117 is a novel STAT3 inhibitor and may be a promising agent for the development of anticancer drugs.
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Demosthenous, Christos, Guangzhen Hu, Thomas E. Witzig, and Mamta Gupta. "Loss-of-Function Missense Mutations in Tyrosine Phosphatase PTPN6 Deregulate STAT3 Signaling in Diffuse Large B-Cell Lymphoma." Blood 124, no. 21 (December 6, 2014): 707. http://dx.doi.org/10.1182/blood.v124.21.707.707.
Abstract:
Abstract Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin Lymphoma and is characterized by deregulation of several signal transduction pathways. Approximately 50% patients with DLBCL are shown to have aberrant activation of the signal transducer and activator of transcription (STAT) pathway. However, mechanism of aberrant STAT3 signaling in DLBCL is not well understood. Protein tyrosine phosphatases (PTPs) are important enzymes that control the activity of multiple signaling pathways downstream of tyrosine kinases; mutations in PTPN11 have been found associated with the development of myeloproliferative disorder. In the current study, we sequenced a set of 38 DLBCL tumor samples for genetic mutations of PTPN6. Bi-directional sequencing reactions were performed on genomic DNA, and all exons of PTPN6 were amplified and analyzed by Sanger sequencing. We identified 2 novel heterozygous missense mutations in PTPN6 gene in 2 separate patients (2/38; 5.2%). The first missense mutation occurred in the exon 7, resulted in an Asp226 to lysine substitution (N226K), while other missense mutation found on exon 15 resulted in an Ala552 to valine substitution (A552V). In order to elucidate the functional significance of these mutations, we performed site directed mutagenesis to mutate wild type (WT) PTPN6 at codon 226 and 552. Both, wild-type PTPN6 (PTPN6WT) or those containing the N226K (PTPN6N226K) and A552V (PTPN6A552V) mutations were cloned and stably expressed in the HEK-293T cells with a lentiviral expression vector and PTPN6 phosphatase activity was measured. Our results showed marked reduction (70%) in the PTPN6 phosphatase activity in both the PTPN6 mutants as compared to the WT control. Interestingly both the PTPN6 mutants (PTPN6N226K and PTPN6A552V) promoted cell proliferation of HEK-293 cells as compared to WT PTPN6. In order to evaluate that whether or not PTPN6 mutations modulate STATs signaling, we analyzed STAT1, STAT3, STAT5 and STAT6 phosphorylation at tyrosine residue in cells stably transfected with WT or mutant PTPN6. While overexpression of WT PTPN6 reduced STAT3 phosphorylation, however no effect was observed on STAT1, STAT5 and STAT6 phosphorylation. Unlike WT-PTPN6, none of the PTPN6 mutants was able to dephosphorylate STAT3. In addition, PTPN6 A552V mutation was found to decrease the ability of PTPN6 to dephosphorylate STAT3 after induction with interleukin-10. Furthermore JAK2/JAK1 inhibition through the pharmacological inhibitor ruxolitinib (5μM) dephosphorylated STAT3 in WT PTPN6 as well as in PTPN6 mutants within 4 hours. Inhibition of JAK3 through a pharmacological inhibitor WHI-P154 (5μM) was able to completely dephosphorylated STAT3, however both the PTPN6 mutants were found resistant to JAK3 inhibition. Moreover, in a luciferase reporter assay compared to WT PTPN6, expressing either of the PTPN6 mutants (N226K and A552V) enhanced transcriptional activity of STAT3. To determine the effect of the PTPN6 mutations on the downstream targets of the JAK/STAT pathway, we demonstrated that Mcl-1, survivin and Bcl-2 protein level was significantly elevated in both mutant cells than that seen in the WT PTPN6 cells. Overall these results demonstrate that the N226K and A552V PTPN6 mutations occur in 5% of DLBCL tumors. Mutations we have found are both able to cause loss-of-function of PTPN6 that leads to increased STAT3 phosphorylation and increased transcriptional activity resulting in accumulation of Mcl-1, Bcl-2 and survivin proteins. Our data suggest that clinical trials of JAK1/JAK2 inhibitors need not be restricted to tumors with PTPN6 mutations but rather should focus on tumors with demonstrated aberrant STAT3 activation. Taken together, our data suggest that PTPN6 mutations may guide the clinical use of inhibitors of JAK3 kinase in DLBCL. Disclosures No relevant conflicts of interest to declare.
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Koppikar, Priya, Omar Abdel-Wahab, Cyrus Hedvat, Sachie Marubayashi, Jay Patel, Aviva Goel, Nicole Kucine, et al. "Efficacy of the JAK2 inhibitor INCB16562 in a murine model of MPLW515L-induced thrombocytosis and myelofibrosis." Blood 115, no. 14 (April 8, 2010): 2919–27. http://dx.doi.org/10.1182/blood-2009-04-218842.
Abstract:
Abstract The discovery of JAK2 and MPL mutations in patients with myeloproliferative neoplasms (MPNs) provided important insight into the genetic basis of these disorders and led to the development of JAK2 kinase inhibitors for MPN therapy. Although recent studies have shown that JAK2 kinase inhibitors demonstrate efficacy in a JAK2V617F murine bone marrow transplantation model, the effects of JAK2 inhibitors on MPLW515L-mediated myeloproliferation have not been investigated. In this report, we describe the in vitro and in vivo effects of INCB16562, a small-molecule JAK2 inhibitor. INCB16562 inhibited proliferation and signaling in cell lines transformed by JAK2 and MPL mutations. Compared with vehicle treatment, INCB16562 treatment improved survival, normalized white blood cell counts and platelet counts, and markedly reduced extramedullary hematopoeisis and bone marrow fibrosis. We observed inhibition of STAT3 and STAT5 phosphorylation in vivo consistent with potent inhibition of JAK-STAT signaling. These data suggest JAK2 inhibitor therapy may be of value in the treatment of JAK2V617F-negative MPNs. However, we did not observe a decrease in the size of the malignant clone in the bone marrow of treated mice at the end of therapy, which suggests that JAK2 inhibitor therapy, by itself, was not curative in this MPN model.
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Cacciapaglia, F., S. Perniola, S. del Vescovo, S. Stano, R. Bizzoca, D. Natuzzi, M. Fornaro, and F. Iannone. "AB0134 IN-VITRO STUDY ON THE EFFECT OF SELECTIVE Jak-INHIBITORS ON PBMCs STAT3 PHOSPHORYLATION FROM SYSTEMIC SCLEROSIS PATIENTS." Annals of the Rheumatic Diseases 81, Suppl 1 (May 23, 2022): 1196.3–1197. http://dx.doi.org/10.1136/annrheumdis-2022-eular.2625.
Abstract:
BackgroundSystemic sclerosis (SSc) is a rare autoimmune connective tissue disease characterized by autoimmunity-driven damage and vasculopathy leading to fibrosis of the skin and internal organs (1). The Janus kinase (Jak) - signal transducer and activator of transcription (STAT) pathway has been evidenced markedly activated in SSc patients (2, 3), and its inhibition has been proved in preclinical and clinical trials (4), but no data on Jak selective inhibition are available.ObjectivesTo explore the effect of selective inhibition of Jak/STAT pathway in peripheral blood mononuclear cells (PBMC) from SSc patients.MethodsIn vitro Jak inhibition of the subunit 3 of phosphorylated (p) than activated STAT was measured by flow cytometry in peripheral blood mononuclear cells (PBMC) from SSc patients naïve to any immunosuppressive and/or corticosteroids (n.5). pSTAT3 activity was also assessed after stimulation with recombinant human 0.1 ng/ml IL-6 (Peprotech – NJ, USA). The PBMC were overnight incubated with IC50 concentrations of selective Jak1-, Jak2-, Jak3- and Tyk2-inhibitors (Biovision Inc. – CA, USA). Percentages of pSTAT3 positive cells were compared in presence of different compounds stimulation.ResultsAfter overnight incubation, percentage of pSTAT3 positive cells was significantly higher in CD14pos compared to CD4pos (16.3%; 95CI 10-22 vs 10.7%; 95CI 4--18, – p=0.02). pSTAT3posCD14pos cells were halved only by selective Jak3-inhibitor, while pSTAT3posCD4pos cells were reduced by 36% by selective Jak1-inhibitor. Selective Jak2- or Tyk2-inhibitors did not interfere with STAT3 phosphorylation in PBMC from SSc patients. After IL-6 stimulation, we observed a 2- and a 1.5-fold increase in percentage of pSTAT3posCD4pos and pSTAT3posCD14pos cells, respectively. pSTAT3posCD14pos cells were reduced in the PBMC co-culture with IL-6 and Jak-selective inhibitors, in contrast no effects were found in CD4pos cells. Specifically, selective Jak1- and Jak3-inhibitors reduced pSTAT3posCD14pos cells by an average of 37% and 25%, respectively. No effects were observed after co-culture with IL-6 and selective Jak2- or Tyk2-inhibitors.ConclusionJak/STAT3 pathway of PBMC from SSc patients with active disease may be differently modulated by specific inhibitors. Selectivity of Jak1- and Jak3-inhibitors seems more relevant, especially in CD14pos monocytes after IL-6 stimulation. These preliminary findings highlight some evidence for effectiveness of selective Jak-inhibitors in SSc treatment.References[1]Benfaremo D, et al. Systemic Sclerosis: From Pathophysiology to Novel Therapeutic Approaches. Biomedicines. 2022;10(1):163.[2]Talotta R. The rationale for targeting the JAK/STAT pathway in scleroderma-associated interstitial lung disease. Immunotherapy. 2021;13(3):241-256.[3]Cacciapaglia F, et al. Phosphorylated signal transducer and activator of transcription 3 (pSTAT3) is highly expressed in CD14+ circulating cells of scleroderma patients. Rheumatology (Oxford). 2020;59(6):1442-1444.[4]Karalilova RV, et al. Tofacitinib in the treatment of skin and musculoskeletal involvement in patients with systemic sclerosis, evaluated by ultrasound. Rheumatol Int. 2021;41(10):1743-1753.Disclosure of InterestsNone declared
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Cacciapaglia, F., V. Venerito, S. del Vescovo, S. Stano, R. Bizzoca, D. Natuzzi, N. Lacarpia, M. Fornaro, and F. Iannone. "AB0070 INHIBITION OF STAT3 IN PBMCs FROM RHEUMATOID ARTHRITIS PATIENTS: CLUES TO UNDERSTAND SELECTIVITY OF JANUS KINASE INHIBITORS." Annals of the Rheumatic Diseases 81, Suppl 1 (May 23, 2022): 1167.2–1168. http://dx.doi.org/10.1136/annrheumdis-2022-eular.1997.
Abstract:
BackgroundThe Janus kinase (Jak) - signal transducer and activator of transcription (STAT) pathway has 4 Jak proteins and 7 STAT factors that mediate intracellular downstream of cytokine receptors. Targeted small-molecule therapies with different bond affinity to Jak proteins have been demonstrated effective in rheumatoid arthritis (RA) treatment, but the clinical significance of selective inhibition remains unclear.ObjectivesTo explore the effect of selective inhibition of Jak-STAT pathway in peripheral blood mononuclear cells (PBMC) from RA patients compared to healthy donors (HD).MethodsIn vitro Jak inhibition of the subunit 3 of phosphorylated (p) than activated STAT was measured by flow cytometry in peripheral blood mononuclear cells (PBMC) from RA patients with active disease (DAS28>5.1) naïve to any DMARDs (n.5) and HD (n.5), following recombinant human 0.1 ng/ml IL-6 (Peprotech – NJ, USA) stimulation. After blood separation, PBMC were overnight incubated with IC50 concentrations of selective Jak1-, Jak2-, Jak3- and Tyk2-inhibitors (Biovision Inc. – CA, USA) with or without IL-6 stimulation. Mean fold-increase of pSTAT3 was then compared in presence of different compounds stimulation.ResultsMean pSTAT3 activity after overnight incubation was significantly higher in RA patients compared to HD (37%; 95CI 8.2-56.7 vs 17.9%; 95CI 4.6-21 – p=0.01). After IL-6 stimulation, a 2-fold and a 1.4-fold increase in pSTAT3 levels was observed in PBMC from RA patients and HD, respectively. In unstimulated PBMC from HD Jak-inhibitors didn’t significantly reduced pSTAT3 activity. In CD14+ cells from RA patients, pSTAT3 activity was reduced with no differences between all four selective Jak-inhibitors, while in CD4+ cells only Jak1-inhibition was able to reduce by 40% pSTAT3 activity. After IL-6 stimulation, the co-culture with Jak1- or JaK3- selective inhibitors was able to significantly reduce pSTAT3 levels in CD4+ lymphocytes, by an average of 20%. While in CD14+ monocytes Jak1-, Jak2- and Jak3- selective inhibitors were able to reduce pSTAT3 activity by a mean of 30%. Tyk-2 selective inhibitor did not interfere with STAT3 activation by IL-6 stimulation of PBMC from RA patients and HD.ConclusionJak/STAT3 activity of PBMC from RA patients with active disease may be differently modulated by specific inhibitors. Selectivity of Jak-inhibitors seems more relevant in lymphocytes after IL-6 stimulation. These preliminary findings may explain discrepancies in effectiveness of selective Jak-inhibitors and pave the way for different choices in clinical practice.References[1]Tanaka Y, et al. Nat Rev Rheumatol. 2022 Jan 5:1–13.[2]Traves PG, et al. Ann Rheum Dis. 2021 Jul;80(7):865-875.[3]Choy EH. Rheumatology (Oxford). 2019 Jun 1;58(6):953-962.Disclosure of InterestsNone declared
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Kapuria, Vaibhav, Geoffrey Bartholomeusz, Ling-Yuan Kong, William Bornmann, Zhenghong Peng, Ashutosh Pal, David Maxwell, Moshe Talpaz, and Nicholas Donato. "A Novel Small-Molecule Approach To Inhibit Jak2 Tyrosine Kinase Signaling." Blood 110, no. 11 (November 16, 2007): 1556. http://dx.doi.org/10.1182/blood.v110.11.1556.1556.
Abstract:
Abstract Jak kinases are non-receptor protein tyrosine kinases that play a pivotal role in cytokine/growth factor signaling through phosphorylation of specific proteins such as the Stat molecules. Activated Stats translocate to the nucleus where they mediate transcription of several target genes involved in cell cycle progression and survival (Bcl-xL, cyclin D1, c-myc, survivin. Many tumors have highly activated Stats that are associated with aberrant Jak2 regulation and recent studies have shown that activating mutations in Jak2 (V617F) play a key role in many myeloproliferative disorders such as polycythemia vera and essential thrombocythemia. Jak inhibitors may be useful in treating many diseases with aberrant Jak2/Stat signaling. The most commonly used inhibitor of Jak2 is the tyrphostin AG490, which inhibits Stat3 activation by preventing its tyrosine phosphorylation. However AG490 has limited in vivo efficacy and must be administered at high concentrations (>50 μM) for anti-tumor effects. We describe here a new class of compounds, termed degrasyns, that block Jak2 mediated activation of Stat3 in intact cells at high nM to low μM concentrations. Degrasyns (WP1130/CP2005) did not directly inhibit Jak2 tyrosine kinase activity but suppressed Stat3 activation by reducing the cytoplasmic levels of Jak2. Degrasyn-mediated Jak2 down-regulation was rapid (complete in 2 hrs) and not inhibited by proteasomal, lysosomal, or serine/threonine protease inhibitors. Biochemical studies and confocal microscopy show that degrasyn induces translocation of Jak2 from the plasma membrane/cytosolic fraction into the cytoskeletal fraction and this altered partitioning of Jak2 was associated with loss of cytokine-mediated Stat activation by degrasyn. Jak2 translocation was associated with tyrosine phosphorylation of specific proteins which complex with Jak2. Lyn kinase in the cytoskeletal fraction was highly activated by degrasyn in multiple hematopoetic tumors (multiple myeloma, mantle cell lymphoma, leukemias). Jak2 translocation and Stat inhibition by degrasyn is mechanistically distinct from “classical” Jak2 inhibitors and is not associated with a translocation of other kinases or cytokine signaling molecules in the Jak2 cascade (IL-6R, gp130, Lyn, Btk, Hck, Akt, PI-3K, Erk, Src, Jak1). Degrasyn induces cytoskeletal translocation of both wild-type and mutant (V617F) Jak2 and was associated with induction of apoptosis in HEL cells expressing the Jak2 V617F mutation. These results suggest that degrasyn suppresses Jak/Stat signaling through a unique mechanism involving translocation of Jak2 into a signal transduction incompetent compartment and may be used to investigate a novel form of Stat suppression. Degrasyn may also have anti-tumor effects on cells with aberrant activation of Jak/Stat signaling.
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Ma, Frank Y., Greg M. Anderson, Travis D. Gunn, Vincent Goffin, David R. Grattan, and Stephen J. Bunn. "Prolactin Specifically Activates Signal Transducer and Activator of Transcription 5b in Neuroendocrine Dopaminergic Neurons." Endocrinology 146, no. 12 (December 1, 2005): 5112–19. http://dx.doi.org/10.1210/en.2005-0770.
Abstract:
The hypothalamic neuroendocrine dopaminergic (NEDA) neurons are crucial in regulating prolactin secretion from the anterior pituitary. Rising prolactin concentrations stimulate these neurons to secrete dopamine, which acts via the pituitary portal vasculature to inhibit additional prolactin release. Prolactin is known to activate Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling pathways in other cell types, including neurons. The possible role of JAK-STAT signaling in NEDA neurons has therefore been examined in this study using fetal rat mediobasal hypothalamic cell cultures and an adult rat in vivo preparation. Cultured cells expressing the dopamine synthesizing enzyme tyrosine hydroxylase (TH) responded to prolactin with a time-dependent increase in phospho-STAT5, but not phospho-STAT1 or phospho-STAT3, nuclear labeling. This response was inhibited by the prolactin receptor antagonist Δ1–9-G129R-human prolactin and the JAK inhibitor AG490, but was unaffected by selected serine/threonine kinase inhibitors (H89, KN-93, bisindolymaleimide, or PD98059). Antibodies selective for STAT5a or STAT5b indicated that the response was restricted to STAT5b, with the number of TH cells displaying STAT5b nuclear immunoreactivity rising from less than 10% under basal conditions to approximately 70% after prolactin stimulation. STAT5a nuclear labeling remained unchanged at 6–10% of TH-positive cells. STAT5b selectivity was confirmed in vivo, where the injection of prolactin into bromocriptine-treated rats stimulated a time-dependent increase in STAT5b, but not STAT5a, nuclear staining in the TH-expressing neurons in the arcuate nucleus. These results extend our previous findings with STAT5b-deficient mice and strongly suggest that in NEDA neurons, prolactin signaling via the JAK/STAT pathway is mediated exclusively by STAT5b.
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Aue, Arman, Franziska Szelinski, Sarah Y. Weißenberg, Annika Wiedemann, Thomas Rose, Andreia C. Lino, and Thomas Dörner. "Elevated STAT1 expression but not phosphorylation in lupus B cells correlates with disease activity and increased plasmablast susceptibility." Rheumatology 59, no. 11 (May 1, 2020): 3435–42. http://dx.doi.org/10.1093/rheumatology/keaa187.
Abstract:
Abstract Objectives SLE is characterized by two pathogenic key signatures, type I IFN and B-cell abnormalities. How these signatures are interrelated is not known. Type I-II IFN trigger activation of Janus kinase (JAK) – signal transducer and activator of transcription (STAT). JAK-STAT inhibition is an attractive therapeutic possibility for SLE. We assess STAT1 and STAT3 expression and phosphorylation at baseline and after IFN type I and II stimulation in B-cell subpopulations of SLE patients compared with other autoimmune diseases and healthy controls (HD) and related it to disease activity. Methods Expression of STAT1, pSTAT1, STAT3 and pSTAT3 in B and T cells of 21 HD, 10 rheumatoid arthritis (RA), seven primary Sjögren’s (pSS) and 22 SLE patients was analysed by flow cytometry. STAT1 and STAT3 expression and phosphorylation in PBMCs (peripheral blood mononuclear cells) of SLE patients and HD after IFNα and IFNγ incubation were further investigated. Results SLE patients showed substantially higher STAT1 but not pSTAT1 in B- and T-cell subsets. Increased STAT1 expression in B-cell subsets correlated significantly with SLEDAI and Siglec-1 on monocytes, a type I IFN marker. STAT1 activation in plasmablasts was IFNα dependent while monocytes exhibited dependence on IFNγ. Conclusion Enhanced expression of STAT1 by B-cell candidates as a key node of two immunopathogenic signatures (type I IFN and B-cells) related to important immunopathogenic pathways and lupus activity. We show that STAT1 is activated upon IFNα exposure in SLE plasmablasts. Thus, Jak inhibitors, targeting JAK-STAT pathways, hold a promise to block STAT1 expression and control plasmablast induction in SLE.
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Nelson, Erik A., Sarah R. Walker, Alicia Kepich, Shariya Terrell, Laurie Gashin, and David A. Frank. "Pimozide Inhibits STAT5 Signaling in Chronic Myelogenous Leukemia and Reduces the Viability of Both Imatinib Sensitive and Imatinib Resistant Cells." Blood 110, no. 11 (November 16, 2007): 2953. http://dx.doi.org/10.1182/blood.v110.11.2953.2953.
Abstract:
Abstract Chronic myelogenous leukemia (CML) is characterized by the BCR/ABL fusion tyrosine kinase which mediates its oncogenic effects in part through constitutive activation of the transcription factor STAT5. BCR/ABL can be inhibited by several kinase inhibitors, including imatinib, which leads to apoptosis of the cells. However, the development of resistance to these agents, most commonly mediated through point mutations in the kinase, is an increasing problem. Since STAT5 is a critical mediator of the effects of BCR/ABL, the development of drugs inhibiting this transcription factor holds promise as an independent means to inhibit BCR/ABL-transformed cells. Therefore, we developed a high throughput cell-based screen to identify drugs that specifically inhibit the transcriptional function of STAT proteins. To accelerate the introduction of active agents into clinical trials, we have focused on drugs that are approved for use, or are otherwise known to be safe, in humans. Using this approach, we have identified pimozide, a neuroleptic drug, as an inhibitor of STAT5. Pimozide decreases STAT5 phosphorylation in CML cells but, in contrast to imatinib, it does not inhibit BCR/ABL kinase activity. Furthermore, pimozide decreases expression of STAT5 target genes in these cells. Consistent with the known role of STAT5 in promoting the survival and proliferation of BCR/ABL-transformed cells, pimozide induces apoptosis in the K562 CML cell line. At similar concentrations, pimozide induces little toxicity in peripheral blood mononuclear cells from normal donors. Given the clinical importance of point mutations in BCR/ABL in the development of resistance to tyrosine kinase inhibitors, we evaluated the effects of pimozide in Ba/f3 cells reconstituted with wildtype BCR/ABL or BCR/ABL containing a T315I mutation, which is highly resistant to current kinase inhibitors. Pimozide reduces the viability of both cell types with similar dose response, providing further support to the hypothesis that this drug works by a mechanism distinct from imatinib. Given this, we considered the possibility that the combination of pimozide and imatinib might be more effective than either drug alone. Treatment of KU812 CML cells with low concentrations of both pimozide and imatinib induced greater loss of viability than either drug alone, with characteristics consistent with pharmacological synergy. In addition, combination treatment with pimozide and imatinib induces a greater level of apoptosis in CML cells than either drug alone. In conclusion, we have identified pimozide as a STAT5 inhibitor that is effective at reducing the viability of CML cells, including those resistant to imatinib. This suggests that the identification of inhibitors of STAT transcription factors may be a promising method for developing new anti-cancer therapies. In addition, the use of pimozide alone or in conjunction with kinase inhibitors may be an important new strategy for the treatment of CML or other diseases characterized by constitutive STAT activation.
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Simon, Amy R., Satoe Takahashi, Mariano Severgnini, Barry L. Fanburg, and Brent H. Cochran. "Role of the JAK-STAT pathway in PDGF-stimulated proliferation of human airway smooth muscle cells." American Journal of Physiology-Lung Cellular and Molecular Physiology 282, no. 6 (June 1, 2002): L1296—L1304. http://dx.doi.org/10.1152/ajplung.00315.2001.
Abstract:
Airway remodeling, as manifested by an increase in airway smooth muscle mass, mucous gland hyperplasia, and subepithelial fibrosis, contributes to the airway hyperresponsiveness and fixed obstruction seen in some asthmatic patients. Here we investigated whether the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway contributes to platelet-derived growth factor (PDGF)-stimulated mitogenesis of human airway smooth muscle cells (HASMC). PDGF treatment of quiescent HASMC resulted in the rapid tyrosine phosphorylation and DNA binding of STAT1 and STAT3. This phosphorylation was blocked by inhibition of Src and JAK2 kinases. In addition, STAT activation by PDGF was found to be redox dependent. Moreover, PDGF-induced thymidine uptake was completely blocked by pretreatment of HASMC with the STAT kinase inhibitors AG-490, SU-6656, and PP2. Interestingly, the JAK pathway was required for HASMC mitogenesis independently of mitogen-activated protein kinase activation. Inhibition of the Src and JAK kinases blocked PDGF-stimulated gene expression of the STAT target genes cyclin D1 and c- myc. These results indicate that the JAK-STAT pathway contributes to PDGF-induced mitogenesis, and thus this pathway may be important in the airway remodeling seen in some asthmatic patients.
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Verdeil, Grégory, Toby Lawrence, Anne-Marie Schmitt-Verhulst, and Nathalie Auphan-Anezin. "Targeting STAT3 and STAT5 in Tumor-Associated Immune Cells to Improve Immunotherapy." Cancers 11, no. 12 (November 21, 2019): 1832. http://dx.doi.org/10.3390/cancers11121832.
Abstract:
Oncogene-induced STAT3-activation is central to tumor progression by promoting cancer cell expression of pro-angiogenic and immunosuppressive factors. STAT3 is also activated in infiltrating immune cells including tumor-associated macrophages (TAM) amplifying immune suppression. Consequently, STAT3 is considered as a target for cancer therapy. However, its interplay with other STAT-family members or transcription factors such as NF-κB has to be considered in light of their concerted regulation of immune-related genes. Here, we discuss new attempts at re-educating immune suppressive tumor-associated macrophages towards a CD8 T cell supporting profile, with an emphasis on the role of STAT transcription factors on TAM functional programs. Recent clinical trials using JAK/STAT inhibitors highlighted the negative effects of these molecules on the maintenance and function of effector/memory T cells. Concerted regulation of STAT3 and STAT5 activation in CD8 T effector and memory cells has been shown to impact their tumor-specific responses including intra-tumor accumulation, long-term survival, cytotoxic activity and resistance toward tumor-derived immune suppression. Interestingly, as an escape mechanism, melanoma cells were reported to impede STAT5 nuclear translocation in both CD8 T cells and NK cells. Ours and others results will be discussed in the perspective of new developments in engineered T cell-based adoptive therapies to treat cancer patients.
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Tian, Q., H. R. Wang, M. Z. Wang, C. Wang, and S. M. Liu. "Lactogenic hormones regulate mammary protein synthesis in bovine mammary epithelial cells via the mTOR and JAK–STAT signal pathways." Animal Production Science 56, no. 11 (2016): 1803. http://dx.doi.org/10.1071/an14113.
Abstract:
The expression of CSN3, hormone receptor, the expression of genes regulating the mTOR, JAK–STAT signal pathways, and the relative content of к-casein as well as total casein were determined in the present study to explore the mechanism of the effect of lactogenic hormones on milk-protein synthesis in bovine mammary epithelial cells. The results showed that apoptosis of the cells was increased by inhibitor LY294002, while the expressions of genes encoding PKB, Rheb, PRAS40 and S6K1 in the mTOR signal pathway, JAK2, STAT5A in the JAK–STAT signal pathway, and genes encoding INSR, PRLR, NR3C1 and CSN3 were all downregulated, and the relative contents of κ-casein and total casein were decreased in the mammary epithelial cells compared with those in the control group. Comparatively, the inhibitory effects of AG-490 were more profound than those of LY294002, and the double block using both inhibitors had a greater effect than the single block. The CSN3 gene expression was downregulated and the content of milk casein was decreased by the inhibitors. In addition, the expression of the hormone receptor genes was downregulated. Our results suggest that lactogenic hormones, via their receptors in the membrane, regulated the JAK–STAT and m-TOR signal pathways, and affected cell proliferation and apoptosis, leading to changes in milk-protein synthesis.
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Schwartz, Daniella M., Aran Son, Francoise Meylan, Julio Gomez-Rodriguez, Zenia Kaul, McKella Sylvester, Moses Kitakule, et al. "Dynamic chromatin accessibility licenses STAT5- and STAT6-dependent innate-like function of Th9 cells to promote allergic inflammation." Journal of Immunology 210, no. 1_Supplement (May 1, 2023): 67.21. http://dx.doi.org/10.4049/jimmunol.210.supp.67.21.
Abstract:
Abstract Allergic diseases are a major global health issue, causing significant morbidity and mortality. Interleukin-9 (IL-9) producing T helper 9 (Th9) cells promote allergic inflammation, yet Th9 effector functions are incompletely understood because the heterogeneity and instability of Th9 cells makes them challenging to study. Although the significance and mechanisms of Th9 instability are unknown, T cell receptor (TCR) activation is hypothesized to play a key role. Conversely to this paradigm, we found that resting Th9 cells did not require TCR restimulation for IL-9 production, which was induced by STAT5- and STAT6-dependent paracrine cytokines. This mechanism was seen in circulating T cells from allergic patients and was restricted to recently activated cells. Analysis of IL-9 +T cells from allergic subjects revealed a transcriptional program that was enriched for activation pathways and unstable over time, with IL9 amongst the least stable genes. Prolonged resting of cells decreased the accessibility of STAT5-dependent IL9 enhancers, inactivating the locus. In vivo, Th9 cells induced airway inflammation via TCR-independent, STAT-dependent mechanisms. In allergic patients, Th9 expansion was associated with STAT activation and responsiveness to JAK inhibitors. These findings suggest that Th9 instability is a negative checkpoint on TCR-independent inflammation that breaks down in allergic disease, and that JAK inhibitors should be considered for allergic patients with a Th9 signature. Supported by the NIAID intramural research program (2018-2022), University of Pittsburgh start-up funds (2022-current), and the National Psoriasis Foundation (Robertson Fellowship, 2018-2021; Translational Grant, 2022-current)
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Zong, Hongliang, Tony Taldone, Gail J. Roboz, Gabriela Chiosis, and Monica L. Guzman. "A Hyperactive Signalosome Results in High Sensitivity to HSP90 Inhibitors in AML." Blood 126, no. 23 (December 3, 2015): 2567. http://dx.doi.org/10.1182/blood.v126.23.2567.2567.
Abstract:
Abstract HSP90 is well established in supporting tumorigenesis by stabilizing oncogenic client proteins. Given this crucial role, a number of HSP90 inhibitors have been tested in various types of cancer, including leukemia. However, clinical trials thus far revealed only a subset of AML patients benefited from the treatment. Therefore, precision medicine approaches to define parameters that predict the patients' response to HSP90 inhibitors are needed to select patients who are most likely to benefit. We have previously demonstrated that PU-H71, a novel purine scaffold HSP90 inhibitor with selectivity for a tumor-specific HSP90 and currently translating into Phase 2 clinical evaluation, is capable of ablating malignant blasts, progenitor and stem cells in AML patient samples using in vitro studies. We found that leukemia cell lines (n=18) and primary AML patient samples (n=26) with greater numbers of simultaneously activated signaling networks, including PI3K-AKT and JAK-STAT, were the most sensitive to HSP90 inhibition. Using different genetic models, our studies revealed that diverse oncogenic transformations that converge upon simultaneous hyperactivation of PI3K-AKT and JAK-STAT promote sensitivity to PU-H71. To validate the efficacy of PU-H71 in vivo, we generated AML-GFP-luciferase xenograft models using cell lines with hyperactive signalosome. Xenotransplanted mice were treated with PU-H71 one week post-engraftment. In vivo imaging indicated that MOLM-13 xenografted leukemia was rapidly and significantly reduced by PU-H71 treatment. Six doses of PU-H71 produced robust anti-leukemic activity as indicated by in vivo imaging and flow cytometric analysis of post-treatment bone marrow (no disease detected). In addition, we generated 7 AML patient-derived xenografts (PDX) cohorts with samples that displayed varied levels of activation of PI3K-AKT and JAK-STAT signaling pathways. After initial validation that status of the PI3K-AKT and JAK-STAT signaling pathways were preserved in the PDX, we initiated treatment with PU-H71 and found that, as predicted, the AML-PDX with the most hyperactive signalosome were the most sensitive to in vivo treatment to PU-H71. Importantly, samples with hyperactive PI3K-AKT and JAK-STAT signaling also demonstrated a significant reduction in LSC using secondary transplants. Taken together, we found that a hyperactive signalosome results in increased sensitivity to the HSP90 inhibitor PU-H71 in vitro and in vivo. Our study suggests that evaluation of PI3K-AKT and JAK-STAT signaling pathways may provide a means to select patients who are most likely to benefit from HSP90 inhibitory therapy. Disclosures No relevant conflicts of interest to declare.
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Furqan, Muhammad, Akintunde Akinleye, Nikhil Mukhi, Varun Mittal, Yamei Chen, and Delong Liu. "STAT inhibitors for cancer therapy." Journal of Hematology & Oncology 6, no. 1 (2013): 90. http://dx.doi.org/10.1186/1756-8722-6-90.