Academic literature on the topic 'Tumor-derived LXR ligand'

BackgroundMyeloid-derived suppressor cells (MDSCs) represent a diverse population of immature myeloid cells with a strong capacity to suppress the functions of NK cells and CD4+ and CD8+ T-cells in tumor immune microenvironment, thereby reducing the efficacy of immunotherapeutic drugs. MDSC depletion strategies are being investigated to determine if the immunosuppressive effects of MDSCs in the tumor microenvironment can be reduced to improve the efficacy of cancer immunotherapy. Here we employed the 3D-Explore ex vivo platform to test the efficacy of MDSC targeting agents alone and in combination with nivolumab using patient derived 3D-tumoroids which retain the tumors’ original stroma and suppressive immune landscape.Methods3D-tumoroids approximately 150 µm in size were generated from fresh patient renal cell carcinoma tumor samples, which were obtained with informed consent and relevant IRB approval. Tumoroids were treated ex vivo with a Phosphodiesterase-5 inhibitor Tadalafil, an HDAC inhibitor entinostat, a potent steroidal liver X receptor (LXR) ligand DMHCA or a selective CK2 (casein kinase II) inhibitor TBCA alone and in combination with nivolumab. Flow cytometry, high content confocal analysis and cytokine release assays were performed to monitor treatment-mediated changes in tumor immune landscape and tumor cell killing.ResultsMulti-parameter flow cytometry (14 color) analysis demonstrated the heterogeneity of tumor immune cell populations including polymorphonuclear (PMN-MDSC) and monocytic (M-MDSC) MDSCs in different patient tumor samples. Furthermore, we performed flow cytometry analysis to assess treatment-induced changes in NK and effector T-cells activation and proliferation profiles that were further correlated with drug impacts on MDSC, Tregs and myeloid cell populations in the ex vivo treatment groups. Additionally, immune cell functions were assessed by multiplex cytokine analysis and treatment-induced tumor cell killing was quantified by high content confocal imaging.ConclusionsOur data demonstrated that the ex vivo 3D-Explore is a clinically relevant platform to identify combination of immunotherapy agents capable of overcoming the unique suppressive environment developed by an individual tumor. Furthermore, the 3D-EXplore platform provides unique insight into the intact tumor immune microenvironment to develop therapeutic strategies to overcome immunosuppressive effects of MDSCs to improve the efficacy of immunotherapeutic agents in cancer.

Abstract While immunotherapies have demonstrated success in solid malignancies, they have limited efficacy in triple negative breast cancer (TNBC). The liver-X-receptors (LXR) are modulators of metabolism and are known to inhibit pro-inflammatory (Th17 and Th1) and increase anti-inflammatory (Tregs) T-cell differentiation. Colorectal and hematologic cancer cells have also been demonstrated to suppress immune function through production of endogenous LXR agonists. Here we show that targeted suppression of LXR activity using the inverse agonist, SR9243, induces immune-mediated tumor destruction in an orthotopic TNBC model. FACs analysis on tumors revealed a significant increase in Th1 and cytotoxic CD8+ T-cells and a decrease in tumor promoting myeloid derived suppressor cells (MDSCs) in response to SR9243. Intratumor immune cell activation coincided with enhanced dendritic cell (DC) lymph node homing and activity. SR9243 also enhanced Th1 CD4+ and CD8+ cell proliferation in the presence of immune-suppressive tumor conditioned media and cancer cell lysates an in vitro model of the tumor-microenvironment. Metabolic analysis of immune cells exposed to LXR-ligands revealed that LXR activation by tumor-produced ligands or synthetic agonists blocks T-cell glycolytic activity essential to immune cell proliferation and activation in response to tumor antigens. Similarly, we observed that LXR activation disrupts de novo cholesterol synthesis which has been shown to be vital to immune synapse formation between T-cells and DCs. Our results suggest that LXR inverse agonists can be used as immunotherapy drugs to treat TNBC by blocking tumor-induced dysregulation of T-cell metabolism.

BackgroundBreast cancer (BrC) is the most prevalent cancer in women worldwide. Unfortunately, still limited treatment options are available for the most aggressive subtypes (i.e. hormone receptor [HR] negative). The response to neoadjuvant chemotherapy (NACT) in patients with HR-negative BrC can in part be influenced by an effective anti-tumor immune response. The sentinel lymph node (SLN) is the first site where BrC-specific T cell priming will occur but unfortunately it is also a major target of BrC-induced immune suppression. Lymph-node resident dendritic cells (LNR-DC) were found to be suppressed in metastatic SLN.1 In addition, this tumor-mediated immune suppression of LNR-DC is related to high-risk triple-negative BrC and may be a negative predictor for prognosis1. Preliminary data showed that NACT further reduced the activation status of LNR-DC. The goal of this study is to identify immune-enhancing agents that can counteract the tumor-mediated immune suppression of LNR-DC and promote tumor-specific T cell responses in order to improve therapy outcome in BrC patients upon NACT.Materials and MethodsPhenotypic analyses were performed on immune-cell subsets in human BrC SLN using multi-color flow cytometry. In addition, ex-vivo cultures with human BrC SLN-derived cells and in vivo mouse experiments were performed to study the therapeutic efficacy of Toll-like receptor (TLR)-ligands (R848 and CpG) and a STING-ligand (STING-L; 2’3’-c-di-AM(PS)2(Rp,Rp)).ResultsHigher rates of LNR-DCs, but with an apparently reduced activation state, were found in SLN of NACT-treated patients compared to patients treated with surgery only. A comparative ex-vivo study with SLN cultures on the effects of R848, CpG-B and STING-L showed R848 to be superior in terms of LNR-DC activation. In a Krt14 (K14)-cre;Cdh1F/F;Trp53F/F (KEP) BrC mouse model, the effects of intratumoral administration of TLR- and STING-L were determined in combination with doxorubicin. STING-L outperformed R848 and CpG-B in terms of controlling primary tumor growth. Of note, in human ex-vivo cultures CpG-B proved effective in LNR-DC activation when combined with a STAT3 inhibitor, leading to the boosting of mammaglobin-specific T cell responses, Th1 skewing, and a drop in CpG-induced Treg levels.ConclusionsIn summary, intratumoral delivery of TLR- and STING-ligands in combination with NACT might be an interesting therapeutic approach in patients with high-risk HR-negative BrC, leading to SLN potentiation and enhanced antitumor T cell immunity. Future clinical studies should demonstrate the therapeutic benefit of this approach.Referencevan Pul, et al. 2019, Journal for ImmunoTherapy of Cancer.Disclosure InformationN. Prokopi: None. M. Heeren: None. I. Milenova: None. K. van Pul: None. T. Muijlwijk: None. M. Arends: None. S. van der Velde: None. K. Vrijland: None. A. van Weverwijk: None. K. de Visser: None. R. van de Ven: None. T. de Gruijl: None.

The androgen receptor (AR) signaling pathway is a common therapeutic target for prostate cancer, because it is critical for the survival of both hormone-responsive and castrate-resistant tumor cells. Most of the detailed understanding that we have of AR transcriptional activation has been gained by studying classical target genes. For more than two decades, Kallikrein 3 (KLK3) (prostate-specific antigen) has been used as a prototypical AR target gene, because it is highly androgen responsive in prostate cancer cells. Three regions upstream of the KLK3 gene, including the distal enhancer, are known to contain consensus androgen-responsive elements required for AR-mediated transcriptional activation. Here, we show that KLK3 is one of a specific cluster of androgen-regulated genes at the centromeric end of the kallikrein locus with enhancers that evolved from the long terminal repeat (LTR) (LTR40a) of an endogenous retrovirus. Ligand-dependent recruitment of the AR to individual LTR-derived enhancers results in concurrent up-regulation of endogenous KLK2, KLK3, and KLKP1 expression in LNCaP prostate cancer cells. At the molecular level, a kallikrein-specific duplication within the LTR is required for maximal androgen responsiveness. Therefore, KLK3 represents a subset of target genes regulated by repetitive elements but is not typical of the whole spectrum of androgen-responsive transcripts. These data provide a novel and more detailed understanding of AR transcriptional activation and emphasize the importance of repetitive elements as functional regulatory units.

Abstract Abstract 1841 PURPOSE: Despite recent advances in the treatment of multiple myeloma (MM), patients with high-risk chromosomal changes such as del13q, t(4;14) or del17p revealed significantly shorter survival. In addition, bone disease markedly reduces quality of life of the patients with MM. To overcome these problems, we have designed and screened synthetic phthalimides which significantly inhibited the growth of MM cell lines with high-risk chromosomal abnormalities. The purposes of this study are to explore novel drugs which possess anti-tumor activity against high-risk MM cells and to examine the anti-osteoclastogenic activity and to isolate directly binding molecules. METHODS AND RESULTS: Thirty synthetic phthalimides were screened for anti-proliferative effect on KMS34 cells with t(4;14) and deletion of chromosome 17. A phthalimide derivative, 2-(2,6-diisopropylphenyl)- 5-amino- 1H-isoindole- 1,3- dione (TC11) significantly inhibited growth of KMS34 cells as well as other MM cells lines with high-risk chromosomal abnormalities (IC50 to KMS34 cells= 4μM). TC11 increased annexin V fraction and induced apoptosis in a caspase-dependent manner. In vivo anti-myeloma activity was evaluated using KMS34-bearing lcr/SCID mice by intraperitoneal injection of TC11. Twenty mg/kg of TC11 significantly inhibited growth of TC11-derived tumor cells, and apoptosis of MM cells was observed by histopathological examination. In order to evaluate hematological toxicity of TC11, growth of colony-forming cells was examined. In the presence of 5μM of TC11, formation of CFCs was not suppressed, suggesting low hematopoietic toxicity. In pharmacokinetic study using lcr/SCID mice, the plasma concentrations of TC11 was examined; Cmax=18.1μM, Tmax=1.5hr, T1/2 =4.5hr when 100mg/kg of TC11 was injected, and Cmax=2.1μM Tmax=1.0hr, T1/2 =4.5hr when 20mg/kg was injected. In order to examine efficacy to bone disease, anti-osteoclastogenic activity was examined by adding TC11 to M-CSF/RANK ligand-induced osteoclastogenic culture of mouse bone marrow mononuclear cells. The number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated osteoclasts was reduced in the presence of 1μM of TC11. It was also found that TC11 inhibited bone resorption by pit assay. We also tried to isolate directly binding proteins to TC11 by our unique in vitro selection system using mRNA display, in vitro virus (IVV) method. We identified nucleophosmin 1 (NPM1) as a TC11-binding molecule. Knockdown assay introducing siRNA for NPM1 into HeLa cells induced emergence of the cells with multipolar spindles, suggesting centrosomal disruption during cell division. Since NPM1 gene localizes at chromosome 5q, anti-MDS effect of TC11 was also examined. TC11 also inhibited growth of MDS-L cells (IC50=7μM). CONCLUSION: A novel phthalimide derivative, TC11, has anti-MM activity in vivo and is a potentially effective drug for high-risk MM with bone lesions. TC11 directly binds to NPM1 and induces apoptosis of MM and MDS cells with low toxicity to normal hematopoiesis. Disclosures: No relevant conflicts of interest to declare.

Abstract Programmed cell death, or apoptosis, is well documented as a physiological means of eliminating activated lymphocytes and maintaining immune homeostasis. Apoptosis has also been implicated in the targeting of tumor cells by cytotoxic T lymphocytes and natural killer cells. One of the two primary mechanisms used in cell-mediated cytotoxicity is the Fas/FasLigand system. Activated or transformed cells expressing the Fas antigen on their surface are susceptible to killing by immune effector cells that express the Fas ligand. Many neoplastic cells, including those derived from patients with multiple myeloma, express Fas antigen on their surface, but do not undergo apoptosis in response to antigen crosslinking. One possibility for the lack of Fas-mediated apoptosis includes mutations in the Fas antigen. Loss of function mutations in the Fas antigen have been associated with congenital autoimmune disease in humans, and have been defined as the genetic defect the in lpr mice. Mutations in the Fas antigen have not been previously described in cancer patients. In this study, we show that mutations occur in the Fas antigen which may cause loss of function and contribute to the pathogenesis of the neoplastic disease, multiple myeloma. Using reverse transcriptase-polymerase chain reaction (RT-PCR), single-stranded conformation polymorphism (SSCP) analysis, and DNA sequencing, we examined the cDNA structure of the Fas antigen in 54 bone marrow (BM) specimens obtained from myeloma patients. Six patient specimens (11%) did not express detectable levels of Fas antigen mRNA. Of the 48 BM specimens which did express Fas antigen, 5 (10%) displayed point mutations. All of the mutations identified were located in the cytoplasmic region of the Fas antigen known to be involved in transduction of an apoptotic signal. Two separate individuals demonstrated an identical mutation at a site previously shown to be mutated in the congenital autoimmune syndrome, ALPS. One patient exhibited a point mutation at a site only two amino acids removed from the documented lesion of the lprcg mouse. Although the functional status of these point mutations remains to be determined, we propose that Fas antigen mutations may contribute to the pathogenesis and progression of myeloma in some patients.

Programmed cell death, or apoptosis, is well documented as a physiological means of eliminating activated lymphocytes and maintaining immune homeostasis. Apoptosis has also been implicated in the targeting of tumor cells by cytotoxic T lymphocytes and natural killer cells. One of the two primary mechanisms used in cell-mediated cytotoxicity is the Fas/FasLigand system. Activated or transformed cells expressing the Fas antigen on their surface are susceptible to killing by immune effector cells that express the Fas ligand. Many neoplastic cells, including those derived from patients with multiple myeloma, express Fas antigen on their surface, but do not undergo apoptosis in response to antigen crosslinking. One possibility for the lack of Fas-mediated apoptosis includes mutations in the Fas antigen. Loss of function mutations in the Fas antigen have been associated with congenital autoimmune disease in humans, and have been defined as the genetic defect the in lpr mice. Mutations in the Fas antigen have not been previously described in cancer patients. In this study, we show that mutations occur in the Fas antigen which may cause loss of function and contribute to the pathogenesis of the neoplastic disease, multiple myeloma. Using reverse transcriptase-polymerase chain reaction (RT-PCR), single-stranded conformation polymorphism (SSCP) analysis, and DNA sequencing, we examined the cDNA structure of the Fas antigen in 54 bone marrow (BM) specimens obtained from myeloma patients. Six patient specimens (11%) did not express detectable levels of Fas antigen mRNA. Of the 48 BM specimens which did express Fas antigen, 5 (10%) displayed point mutations. All of the mutations identified were located in the cytoplasmic region of the Fas antigen known to be involved in transduction of an apoptotic signal. Two separate individuals demonstrated an identical mutation at a site previously shown to be mutated in the congenital autoimmune syndrome, ALPS. One patient exhibited a point mutation at a site only two amino acids removed from the documented lesion of the lprcg mouse. Although the functional status of these point mutations remains to be determined, we propose that Fas antigen mutations may contribute to the pathogenesis and progression of myeloma in some patients.

Abstract BACKGROUND: Despite recent advances in the use of newly developed drugs including immune-modulatory drugs (IMiDs) such as thalidomide, lenalidomide, and pomalidomide and proteasome inhibitors such as bortezomib, carfilzomib, and MLN9708, MM is still an incurable disease. In particular, MM patients harboring 17p deletion, t(14;16), t(14;20), or t(4;14) are classified as a high-risk group and have shown significantly shorter survival. With the goal of helping prolong the survival of these high-risk MM patients, we screened 29 synthetic phthalimide derivatives and found a novel compound, 2-(2,6-diisopropylphenyl)-5-amino-1H-isoindole-1,3-dione (TC11), which induced the apoptosis of KMS34 cells with t(4;14) and del17p13. PURPOSE:The purpose of this project is to clarify preclinical effects of the synthetic phthalimide derivative, TC11, on high-risk MM cell lines and osteoclasts. Namely, anti-myeloma and anti-osteoclastogenic activities and pharmacokinetic study in mice were shown. We also try to isolate directly binding molecules. Safety issues including hematological toxicities and teratogenicity were also discussed. METHODS AND RESULTS: TC11 significantly inhibited growth of MM cell lines (IC50 4-8μM) including KMS34 and KMS11 cells which have high-risk chromosomal abnormalities. TC11 also suppressed the proliferation of all of the bone marrow cells obtained from the MM patients, in a dose-dependent manner. TC11 increased annexin V-positive fraction and induced apoptosis. TC11 was injected intraperitonealy into myeloma (KMS34 and KMS11 cells)-bearing lcr/SCID mice, and anti-myeloma activity was evaluated in vivo. Twenty mg/kg of TC11 significantly inhibited growth of KMS34 or KMS11-derived plasmacytomas. Apoptosis of MM cells was observed by histopathological examination. In order to evaluate hematological toxicity of TC11, growth of colony-forming cells was examined. In the presence of 5μM of TC11, formation of CFCs was not significantly suppressed, suggesting low hematopoietic toxicity. In the pharmacokinetic analyses using lcr mice, the plasma concentrations of TC11 was examined; Cmaxwas 18.1μM at 1.5hr (Tmax), and T1/2 was 2.5hr, when 100mg/kg of TC11 was injected. If 20mg/kg was injected, Cmaxwas 2.1μM at 1.0hr (Tmax), and T1/2 was 1.2hr. Oral administration of TC11 to Icr mice was safely carried out, and results of pharmacokinetic study will be shown. Aiming at the therapeutic use of TC11 to bone disease, anti-osteoclastogenic activity was examined. Mouse bone marrow mononuclear cells were incubated in the presence of M-CSF and RANK-ligand. Tartrate-resistant acid phosphatase (TRAP)-positive multinucleated osteoclasts was reduced in number in the presence of 1μM of TC11. It was also found that 1μM of TC11 inhibited bone resorption by pit assay. We have identified nucleophosmin 1 (NPM1) and α-tubulin as TC11-binding molecules using our unique in vitro selection system using mRNA display, in vitro virus (IVV) method. However, cereblon (CRBN) was not detected as a TC11-binding protein by this method. The immunofluorescent analysis showed that TC11-treated cells exhibited elevated levels of α-tubulin fragmentation. Together with our previous observation of induction of centrosomal disruption of HeLa cells by NPM1-knock down, TC11 may cause anti-myeloma effects via mitotic catastrophe. CONCLUSION: We have demonstrated that TC11, a novel phthalimide derivative, has anti-tumor activity against MM cells with high-risk genetic abnormality including del 17p and t(4;14), in vitro and in vivo. This novel compound also down-regulates the differentiation and function of osteoclasts. Our data provide a strong preclinical rationale for TC11 as a safe and effective drug for the treatment of high-risk MM patients with bone disease. The actions of this drug relating to α-tubulin and NPM1 remain to be further investigated. TC11 exerts its anti-myeloma effect via molecular interactions which do not involve CRBN. In addition, TC11 does not form racemate and is expected to lack teratogenicity. The results of our present study suggest that new phthalimide derivatives other than thalidomide, lenalidomide and pomalidomide could be developed by drug designing for the treatment of MM. Disclosures No relevant conflicts of interest to declare.

The tumor-intrinsic NOD-, LRR- and pyrin domain-containing protein-3 (NLRP3) inflammasome–heat shock protein 70 (HSP70) signaling axis is triggered by CD8 + T cell cytotoxicity and contributes to the development of adaptive resistance to anti–programmed cell death protein 1 (PD-1) immunotherapy by recruiting granulocytic polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) into the tumor microenvironment. Here, we demonstrate that the tumor NLRP3-HSP70 axis also drives the accumulation of PMN-MDSCs into distant lung tissues in a manner that depends on lung epithelial cell Toll-like receptor 4 (TLR4) signaling, establishing a premetastatic niche that supports disease hyperprogression in response to anti–PD-1 immunotherapy. Lung epithelial HSP70-TLR4 signaling induces the downstream Wnt5a-dependent release of granulocyte colony-stimulating factor (G-CSF) and C-X-C motif chemokine ligand 5 (CXCL5), thus promoting myeloid granulopoiesis and recruitment of PMN-MDSCs into pulmonary tissues. Treatment with anti–PD-1 immunotherapy enhanced the activation of this pathway through immunologic pressure and drove disease progression in the setting of Nlrp3 amplification. Genetic and pharmacologic inhibition of NLRP3 and HSP70 blocked PMN-MDSC accumulation in the lung in response to anti–PD-1 therapy and suppressed metastatic progression in preclinical models of melanoma and breast cancer. Elevated baseline concentrations of plasma HSP70 and evidence of NLRP3 signaling activity in tumor tissue specimens correlated with the development of disease hyperprogression and inferior survival in patients with stage IV melanoma undergoing anti–PD-1 immunotherapy. Together, this work describes a pathogenic mechanism underlying the phenomenon of disease hyperprogression in melanoma and offers candidate targets and markers capable of improving the management of patients with melanoma.

Tumour formation is the result of molecular alterations involving cellular regulators as well as the ability of tumor cells to affect the tumor microenvironment through smoldering inflammation, or even taking advantage of inflammation to grow and metastasize. Tumour microenvironment is composed of various cell types, among them neutrophils are recognized as playing an important pro-tumorigenic role, by promoting neoangiogenesis and/or by suppressing antitumor immune responses. We have recently shown that ligands of liver X receptors (LXRs), which are involved in cholesterol homeostasis and in modulating immune responses, are released by cancer cells and suppress antitumor immune responses by dampening dendritic cell migration to draining lymph nodes. Here, we report that natural and tumour-derived LXR ligands attract a subpopulation of bone marrow (BM)- derived cells in a LXR independent, CXCR2 dependent manner. These cells have phenotypic (CD11bhighGr1highLy6G+) and morphological features of neutrophils and favour initial tumour angiogenesis. Moreover, the in vivo inactivation of LXR ligands, the depletion of neutrophils, as well as the pharmacologic and genetic inactivation of CXCR2 inhibit neutrophil recruitment to the tumour and delay tumour growth. Our data reveal an unanticipated chemoattractant role for tumour-derived LXR ligands in promoting tumour growth that relies on the CXCR2-mediated recruitment of neutrophils, thus identifying a new therapeutic target for cancer patients.