Journal articles on the topic 'Autophagy inhibitors'
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1
Körholz, Katharina, Johannes Ridinger, Damir Krunic, Sara Najafi, Xenia F. Gerloff, Karen Frese, Benjamin Meder, et al. "Broad-Spectrum HDAC Inhibitors Promote Autophagy through FOXO Transcription Factors in Neuroblastoma." Cells 10, no. 5 (April 24, 2021): 1001. http://dx.doi.org/10.3390/cells10051001.
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Depending on context and tumor stage, deregulation of autophagy can either suppress tumorigenesis or promote chemoresistance and tumor survival. Histone deacetylases (HDACs) can modulate autophagy; however, the exact mechanisms are not fully understood. Here, we analyze the effects of the broad-spectrum HDAC inhibitors (HDACi) panobinostat and vorinostat on the transcriptional regulation of autophagy with respect to autophagy transcription factor activity (Transcription factor EB—TFEB, forkhead boxO—FOXO) and autophagic flux in neuroblastoma cells. In combination with the late-stage autophagic flux inhibitor bafilomycin A1, HDACis increase the number of autophagic vesicles, indicating an increase in autophagic flux. Both HDACi induce nuclear translocation of the transcription factors FOXO1 and FOXO3a, but not TFEB and promote the expression of pro-autophagic FOXO1/3a target genes. Moreover, FOXO1/3a knockdown experiments impaired HDACi treatment mediated expression of autophagy related genes. Combination of panobinostat with the lysosomal inhibitor chloroquine, which blocks autophagic flux, enhances neuroblastoma cell death in culture and hampers tumor growth in vivo in a neuroblastoma zebrafish xenograft model. In conclusion, our results indicate that pan-HDACi treatment induces autophagy in neuroblastoma at a transcriptional level. Combining HDACis with autophagy modulating drugs suppresses tumor growth of high-risk neuroblastoma cells. These experimental data provide novel insights for optimization of treatment strategies in neuroblastoma.
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Rahman, Md Ataur, Yoonjeong Cho, Hongik Hwang, and Hyewhon Rhim. "Pharmacological Inhibition of O-GlcNAc Transferase Promotes mTOR-Dependent Autophagy in Rat Cortical Neurons." Brain Sciences 10, no. 12 (December 9, 2020): 958. http://dx.doi.org/10.3390/brainsci10120958.
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O-GlcNAc transferase (OGT) is a ubiquitous enzyme that regulates the addition of β-N-acetylglucosamine (O-GlcNAc) to serine and threonine residues of target proteins. Autophagy is a cellular process of self-digestion, in which cytoplasmic resources, such as aggregate proteins, toxic compounds, damaged organelles, mitochondria, and lipid molecules, are degraded and recycled. Here, we examined how three different OGT inhibitors, alloxan, BXZ2, and OSMI-1, modulate O-GlcNAcylation in rat cortical neurons, and their autophagic effects were determined by immunoblot and immunofluorescence assays. We found that the treatment of cortical neurons with an OGT inhibitor decreased O-GlcNAcylation levels and increased LC3-II expression. Interestingly, the pre-treatment with rapamycin, an mTOR inhibitor, further increased the expression levels of LC3-II induced by OGT inhibition, implicating the involvement of mTOR signaling in O-GlcNAcylation-dependent autophagy. In contrast, OGT inhibitor-mediated autophagy was significantly attenuated by 3-methyladenine (3-MA), a blocker of autophagosome formation. However, when pre-treated with chloroquine (CQ), a lysosomotropic agent and a late-stage autophagy inhibitor, OGT inhibitors significantly increased LC3-II levels along with LC3 puncta formation, indicating the stimulation of autophagic flux. Lastly, we found that OGT inhibitors significantly decreased the levels of the autophagy substrate p62/SQSTM1 while increasing the expression of lysosome-associated membrane protein 1 (LAMP1). Together, our study reveals that the modulation of O-GlcNAcylation by OGT inhibition regulates mTOR-dependent autophagy in rat cortical neurons.
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Yang, Cheng, Varsha Kaushal, Sudhir V. Shah, and Gur P. Kaushal. "Autophagy is associated with apoptosis in cisplatin injury to renal tubular epithelial cells." American Journal of Physiology-Renal Physiology 294, no. 4 (April 2008): F777—F787. http://dx.doi.org/10.1152/ajprenal.00590.2007.
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Autophagy has emerged as another major “programmed” mechanism to control life and death much like “programmed cell death” is for apoptosis in eukaryotes. We examined the expression of autophagic proteins and formation of autophagosomes during progression of cisplatin injury to renal tubular epithelial cells (RTEC). Autophagy was detected as early as 2–4 h after cisplatin exposure as indicated by induction of LC3-I, conversion of LC3-I to LC3-II protein, and upregulation of Beclin 1 and Atg5, essential markers of autophagy. The appearance of cisplatin-induced punctated staining of autophagosome-associated LC3-II upon GFP-LC3 transfection in RTEC provided further evidence for autophagy. The autophagy inhibitor 3-methyladenine blocked punctated staining of autophagosomes. The staining of normal cells with acridine orange displayed green fluorescence with cytoplasmic and nuclear components in normal cells but displayed considerable red fluorescence in cisplatin-treated cells, suggesting formation of numerous acidic autophagolysosomal vacuoles. Autophagy inhibitors LY294002 or 3-methyladenine or wortmannin inhibited the formation of autophagosomes but induced apoptosis after 2–4 h of cisplatin treatment as indicated by caspase-3/7 and -6 activation, nuclear fragmentation, and cell death. This switch from autophagy to apoptosis by autophagic inhibitors further suggests that the preapoptotic lag phase after treatment with cisplatin is mediated by autophagy. At later stages of cisplatin injury, apoptosis was also found to be associated with autophagy, as autophagic inhibitors and inactivation of autophagy proteins Beclin 1 and Atg5 enhanced activation of caspases and apoptosis. Our results demonstrate that induction of autophagy mounts an adaptive response, suppresses cisplatin-induced apoptosis, and prolongs survival of RTEC.
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Pasquier, Benoit. "Autophagy inhibitors." Cellular and Molecular Life Sciences 73, no. 5 (December 11, 2015): 985–1001. http://dx.doi.org/10.1007/s00018-015-2104-y.
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Chaikuad, Apirat, Sebastian E. Koschade, Alexandra Stolz, Katarina Zivkovic, Christian Pohl, Shabnam Shaid, Huiyu Ren, et al. "Conservation of structure, function and inhibitor binding in UNC-51-like kinase 1 and 2 (ULK1/2)." Biochemical Journal 476, no. 5 (March 12, 2019): 875–87. http://dx.doi.org/10.1042/bcj20190038.
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Abstract Autophagy is essential for cellular homeostasis and when deregulated this survival mechanism has been associated with disease development. Inhibition of autophagy initiation by inhibiting the kinase ULK1 (Unc-51-like autophagy activating kinase 1) has been proposed as a potential cancer therapy. While inhibitors and crystal structures of ULK1 have been reported, little is known about the other closely related kinase ULK2 (Unc-51-like autophagy activating kinase 2). Here, we present the crystal structure of ULK2 in complex with ATP competitive inhibitors. Surprisingly, the ULK2 structure revealed a dimeric assembly reminiscent of dimeric arrangements of auto-activating kinases suggesting a role for this association in ULK activation. Screening of a kinase focused library of pre-clinical and clinical compounds revealed several potent ULK1/2 inhibitors and good correlation of inhibitor-binding behavior with both ULK kinases. Aurora A was identified as a major off-target of currently used ULK1 inhibitors. Autophagic flux assays demonstrated that this off-target activity by strongly inducing autophagy in different cellular systems conferred an additional layer of complexity in the interpretation of cellular data. The data presented here provide structural models and chemical starting points for the development of ULK1/2 dual inhibitors with improved selectivity for future exploitation of autophagy inhibition.
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Janser, Félice, Olivia Adams, Vanessa Bütler, Anna Schläfli, Bastian Dislich, Christian Seiler, Dino Kröll, Rupert Langer, and Mario Tschan. "Her2-Targeted Therapy Induces Autophagy in Esophageal Adenocarcinoma Cells." International Journal of Molecular Sciences 19, no. 10 (October 8, 2018): 3069. http://dx.doi.org/10.3390/ijms19103069.
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Esophageal adenocarcinoma (EAC) is a highly lethal cancer type with an overall poor survival rate. Twenty to thirty percent of EAC overexpress the human epidermal growth factor receptor 2 (Her2), a transmembrane receptor tyrosine kinase promoting cell growth and proliferation. Patients with Her2 overexpressing breast and gastroesophageal cancer may benefit from Her2 inhibitors. Therapy resistance, however, is well documented. Since autophagy, a lysosome-dependent catabolic process, is implicated in cancer resistance mechanisms, we tested whether autophagy modulation influences Her2 inhibitor sensitivity in EAC. Her2-positive OE19 EAC cells showed an induction in autophagic flux upon treatment with the small molecule Her2 inhibitor Lapatinib. Newly generated Lapatinib-resistant OE19 (OE19 LR) cells showed increased basal autophagic flux compared to parental OE19 (OE19 P) cells. Based on these results, we tested if combining Lapatinib with autophagy inhibitors might be beneficial. OE19 P showed significantly reduced cell viability upon double treatment, while OE19 LR were already sensitive to autophagy inhibition alone. Additionally, Her2 status and autophagy marker expression (LC3B and p62) were investigated in a treatment-naïve EAC patient cohort (n = 112) using immunohistochemistry. Here, no significant correlation between Her2 status and expression of LC3B and p62 was found. Our data show that resistance to Her2-directed therapy is associated with a higher basal autophagy level, which is not per se associated with Her2 status. Therefore, we propose that autophagy may contribute to acquired resistance to Her2-targeted therapy in EAC, and that combining Her2 and autophagy inhibition might be beneficial for EAC patients.
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Dykstra, Kaitlyn M., Hannah R. S. Fay, Ashish C. Massey, Neng Yang, Matthew Johnson, Scott Portwood, Monica L. Guzman, and Eunice S. Wang. "Inhibiting autophagy targets human leukemic stem cells and hypoxic AML blasts by disrupting mitochondrial homeostasis." Blood Advances 5, no. 8 (April 20, 2021): 2087–100. http://dx.doi.org/10.1182/bloodadvances.2020002666.
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Abstract Leukemia stem cells (LSCs) and therapy-resistant acute myeloid leukemia (AML) blasts contribute to the reinitiation of leukemia after remission, necessitating therapeutic interventions that target these populations. Autophagy is a prosurvival process that allows for cells to adapt to a variety of stressors. Blocking autophagy pharmacologically by using mechanistically distinct inhibitors induced apoptosis and prevented colony formation in primary human AML cells. The most effective inhibitor, bafilomycin A1 (Baf A1), also prevented the in vivo maintenance of AML LSCs in NSG mice. To understand why Baf A1 exerted the most dramatic effects on LSC survival, we evaluated mitochondrial function. Baf A1 reduced mitochondrial respiration and stabilized PTEN-induced kinase-1 (PINK-1), which initiates autophagy of mitochondria (mitophagy). Interestingly, with the autophagy inhibitor chloroquine, levels of enhanced cell death and reduced mitochondrial respiration phenocopied the effects of Baf A1 only when cultured in hypoxic conditions that mimic the marrow microenvironment (1% O2). This indicates that increased efficacy of autophagy inhibitors in inducing AML cell death can be achieved by concurrently inducing mitochondrial damage and mitophagy (pharmacologically or by hypoxic induction) and blocking mitochondrial degradation. In addition, prolonged exposure of AML cells to hypoxia induced autophagic flux and reduced chemosensitivity to cytarabine (Ara-C), which was reversed by autophagy inhibition. The combination of Ara-C with Baf A1 also decreased tumor burden in vivo. These findings demonstrate that autophagy is critical for mitochondrial homeostasis and survival of AML cells in hypoxia and support the development of autophagy inhibitors as novel therapeutic agents for AML.
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Holen, I., P. B. Gordon, and P. O. Seglen. "Protein kinase-dependent effects of okadaic acid on hepatocytic autophagy and cytoskeletal integrity." Biochemical Journal 284, no. 3 (June 15, 1992): 633–36. http://dx.doi.org/10.1042/bj2840633.
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The protein phosphatase inhibitor okadaic acid suppressed autophagy completely in isolated rat hepatocytes, as measured by the sequestration of electroinjected [3H]raffinose into sedimentable autophagic vacuoles. Okadaic acid was effectively antagonized by the general protein kinase inhibitors K-252a and KT-5926, the calmodulin antagonist W-7, and by KN-62, a specific inhibitor of Ca2+/calmodulin-dependent protein kinase II (CaMK-II). These inhibitors also antagonized a cytoskeleton-disruptive effect of okadaic acid, manifested as the disintegration of cell corpses after breakage of the plasma membrane. CaMK-II, or a closely related enzyme, would thus seem to play a role in the control of autophagy as well as in the control of cytoskeletal organization.
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Fu, Yuanyuan, Qianqian Gu, Li Luo, Jiecheng Xu, Yuping Luo, Fan Xia, Fanghai Han, et al. "New Anti-Cancer Strategy to Suppress Colorectal Cancer Growth Through Inhibition of ATG4B and Lysosome Function." Cancers 12, no. 6 (June 10, 2020): 1523. http://dx.doi.org/10.3390/cancers12061523.
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Autophagy inhibition has been proposed to be a potential therapeutic strategy for cancer, however, few autophagy inhibitors have been developed. Recent studies have indicated that lysosome and autophagy related 4B cysteine peptidase (ATG4B) are two promising targets in autophagy for cancer therapy. Although some inhibitors of either lysosome or ATG4B were reported, there are limitations in the use of these single target compounds. Considering multi-functional drugs have advantages, such as high efficacy and low toxicity, we first screened and validated a batch of compounds designed and synthesized in our laboratory by combining the screening method of ATG4B inhibitors and the identification method of lysosome inhibitors. ATG4B activity was effectively inhibited in vitro. Moreover, 163N inhibited autophagic flux and caused the accumulation of autolysosomes. Further studies demonstrated that 163N could not affect the autophagosome-lysosome fusion but could cause lysosome dysfunction. In addition, 163N diminished tumor cell viability and impaired the development of colorectal cancer in vivo. The current study findings indicate that the dual effect inhibitor 163N offers an attractive new anti-cancer drug and compounds having a combination of lysosome inhibition and ATG4B inhibition are a promising therapeutic strategy for colorectal cancer therapy.
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Bohusné Barta, Bettina, Ágnes Simon, Lőrinc Nagy, Titanilla Dankó, Regina Eszter Raffay, Gábor Petővári, Viktória Zsiros, Anna Sebestyén, Ferenc Sipos, and Györgyi Műzes. "Survival of HT29 cancer cells is influenced by hepatocyte growth factor receptor inhibition through modulation of self-DNA-triggered TLR9-dependent autophagy response." PLOS ONE 17, no. 5 (May 12, 2022): e0268217. http://dx.doi.org/10.1371/journal.pone.0268217.
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HGFR activation drives the malignant progression of colorectal cancer, and its inhibition displays anti-autophagic activity. The interrelated role of HGFR inhibition and TLR9/autophagy signaling in HT29 cancer cells subjected to modified self-DNA treatments has not been clarified. We analyzed this complex interplay with cell metabolism and proliferation measurements, TLR9, HGFR and autophagy inhibitory assays and WES Simple Western blot-based autophagy flux measurements, gene expression analyses, immunocytochemistry, and transmission electron microscopy. The overexpression of MyD88 and caspase-3 was associated with enhanced HT29 cell proliferation, suggesting that incubation with self-DNAs could suppress the apoptosis-induced compensatory cell proliferation. HGFR inhibition blocked the proliferation-reducing effect of genomic and hypermethylated, but not that of fragmented DNA. Lowest cell proliferation was achieved with the concomitant use of genomic DNA, HGFR inhibitor, and chloroquine, when the proliferation stimulating effect of STAT3 overexpression could be outweighed by the inhibitory effect of LC3B, indicating the putative involvement of HGFR-mTOR-ULK1 molecular cascade in HGFR inhibitor-mediated autophagy. The most intense cell proliferation was caused by the co-administration of hypermethylated DNA, TLR9 and HGFR inhibitors, when decreased expression of both canonical and non-canonical HGFR signaling pathways and autophagy-related genes was present. The observed ultrastructural changes also support the context-dependent role of HGFR inhibition and autophagy on cell survival and proliferation. Further investigation of the influence of the studied signaling pathways and cellular processes can provide a basis for novel, individualized anti-cancer therapies.
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Jia, Li, Ganga Gopinathan, Johanna T. Sukumar, and John G. Gribben. "Potentiation of Bortezomib-Induced Killing of Lymphoma Cells by Inhibition of Autophagy and Prevention of I-κBα Degradation." Blood 116, no. 21 (November 19, 2010): 116. http://dx.doi.org/10.1182/blood.v116.21.116.116.
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Abstract Abstract 116 Previous studies have shown that germinal center B cell-like (GCB) diffuse large B-cell lymphoma (DLBCL) are resistant to proteasome inhibitors such as bortezomib. The mechanism by which GCB-DLBCL cells escape from proteasome inhibitor-induced apoptosis is unclear. To investigate this further, we examined the proteasomal pathway, expression of anti-apoptotic proteins and autophagy. Using bortezomib or MG-262, we show that DLBCL cells have differential sensitivity to proteasome inhibitor-mediated cell death, even though the effects on proteasome inhibition were similar. DLBCL cells that either over-express anti-apoptotic proteins such as Bcl-2, or lack pro-apoptotic proteins including Bax/Bak, are more resistant to proteasome inhibitor-induced reduction of mitochondrial membrane potential and activation of caspase-3. Treatment with bortezomib induced autophagy in both sensitive and resistant DLBCL cells, as demonstrated by an accumulation and aggregation of the autophagy marker protein LC3-II. Bortezomib induced accumulation of ubiquitinated proteins and a decrease in the adaptor protein p62, indicating activation of autophagic degradation. Fluorescent microscopy revealed that bortezomib induced p62 recruits both ubiquitinated proteins and LC3-II, suggesting that p62 leads ubiquitinated protein to autophagosomes. Treatment with bortezomib thereby promotes I-kBα degradation, demonstrating that the route of I-κBα degradation is not via the ubiquitin-proteasome degradation system. Bortezomib-induced I-kBα degradation was detected in both DLBCL cell lines and primary DLBCL and follicular lymphoma samples. Chloroquine (CQ), an inhibitor of autophagy, significantly increased bortezomib-induced accumulation of p62 and ubiquitinated proteins, including I-κBα, Bax and p53. CQ alone induced a dose-dependent increase in I-kBα protein levels, indicating that I-κBα protein can be degraded by autophagy even in the absence of proteasome inhibition. Importantly, the combination of proteasome and autophagy inhibitors shows great potential to kill apoptosis-resistant lymphoma cells. Proteasome inhibitor with or without CQ induced cell death in DLBCL cells cannot be blocked completely by either caspase inhibitors or knockdown of Bax/Bak proteins, suggesting that cell death occurs via a caspase-independent pathway. In summary, proteasome inhibitors induce autophagy and confer DLBCL cells resistance by eliminating I-κBα and possibly other pro-apoptotic proteins. Addition of autophagy inhibitors to bortezomib has the potential to induce increased killing in patients with resistant lymphoma. Disclosures: Gribben: Roche: Consultancy; Celgene: Consultancy; GSK: Honoraria; Napp: Honoraria.
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Hamano, Tadanori, Soichi Enomoto, Norimichi Shirafuji, Masamichi Ikawa, Osamu Yamamura, Shu-Hui Yen, and Yasunari Nakamoto. "Autophagy and Tau Protein." International Journal of Molecular Sciences 22, no. 14 (July 12, 2021): 7475. http://dx.doi.org/10.3390/ijms22147475.
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Neurofibrillary tangles, which consist of highly phosphorylated tau protein, and senile plaques (SPs) are pathological hallmarks of Alzheimer’s disease (AD). In swollen axons, many autophagic vacuoles are observed around SP in the AD brain. This suggests that autophagy function is disturbed in AD. We used a neuronal cellular model of tauopathy (M1C cells), which harbors wild type tau (4R0N), to assess the effects of the lysosomotrophic agent NH4Cl, and autophagy inhibitors chloroquine and 3 methyladenine (3MA). It was found that chloroquine, NH4Cl and 3MA markedly increased tau accumulation. Thus, autophagy lysosomal system disturbances disturbed the degradation mechanisms of tau protein. Other studies also revealed that tau protein, including aggregated tau, is degraded via the autophagy lysosome system. Phosphorylated and C terminal truncated tau were also reported to disturb autophagy function. As a therapeutic strategy, autophagy upregulation was suggested. Thus far, as autophagy modulators, rapamycin, mTOCR1 inhibitor and its analogues, lithium, metformin, clonidine, curcumin, nicotinamide, bexaroten, and torehalose have been proposed. As a therapeutic strategy, autophagic modulation may be the next target of AD therapeutics.
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Luo, Xiaomei, Wei Cheng, Shizhang Wang, Zhihong Chen, and Jieqiong Tan. "Autophagy Suppresses Invasiveness of Endometrial Cells through Reduction of Fascin-1." BioMed Research International 2018 (June 11, 2018): 1–9. http://dx.doi.org/10.1155/2018/8615435.
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Objective. Autophagy has been reported to be involved in the development of various disorders such as neurodegenerative and metabolic diseases and tumors. Autophagy activators and inhibitors are also potential therapeutics for these diseases. However, the mechanism of autophagic involvement in different diseases is not the same, and the role of autophagy in endometriosis (EM) has not yet been elucidated. This research investigated the mechanism by which autophagy acts in EM, with the aim of establishing a theoretical basis for its prevention and treatment through the targeted interference with autophagy. Methods. We used an RNA interference fragment targeting ATG5, the autophagy activator rapamycin, and the autophagy inhibitor 3-MA or overexpression of filopodia-related protein fascin-1, in conjunction with clonogenic assays, growth curves, and scratch assay to investigate the influence of autophagy on cellular growth, proliferation, and invasiveness. We collected specimens from 20 clinical cases of EM and investigated the protein expression of the autophagic marker LC3-II, the autophagic substrate p62, and fascin-1. Results. Rapamycin was able to inhibit the proliferation and colony formation of the endometriotic cell line CRL-7566, whereas the autophagy inhibitor 3-MA as well as the interference with the autophagy-related gene ATG5 had the opposite effect. More importantly, the autophagy activator rapamycin was able to inhibit the growth of filopodia in the endometriotic cells, and the overexpression of the fascin-1 restored the rapamycin-induced decrease of invasiveness. We found that the expression of the autophagy marker LC3-II was significantly reduced among the clinical EM specimens compared to the control group, while the expressions of fascin-1 and autophagic substrate p62 were increased. Conclusion. Our results indicate that the inhibition of autophagy and exogenous expression of fascin-1 may promote the invasiveness of endometrial cells. As a corollary, autophagy represents a potential target for the treatment of EM.
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Zhang, Hai-Yan, Zhen-Xian Du, Xin Meng, Zhi-Hong Zong, and Hua-Qin Wang. "Beclin 1 Enhances Proteasome Inhibition-Mediated Cytotoxicity of Thyroid Cancer Cells in Macroautophagy-Independent Manner." Journal of Clinical Endocrinology & Metabolism 98, no. 2 (February 1, 2013): E217—E226. http://dx.doi.org/10.1210/jc.2012-2679.
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Abstract Context: The ubiquitin–proteasome system and macroautophagy are two major pathways for intracellular protein degradation. Emerging lines of evidence have shown that blockade of ubiquitin–proteasome system by proteasome inhibitors activates macroautophagy. Objective: The purpose of this study was to determine the involvement of autophagy essential gene Beclin 1 in cytotoxicity of thyroid cancer cells mediated by proteasome inhibitors. Design: Autophagy was measured by acidic-trophic dye staining and EGF-LC3 distribution using fluorescence microscopy, as well as LC3-II transition using Western blot. To ascertain the effect of Beclin 1, cells were transfected with Beclin 1 plasmid or shRNA against Beclin 1. Cell viability and apoptotic cells were measured using MTT assay and flow cytometry, respectively. Results: Proteasome inhibitors decreased Beclin 1 expression. In addition, treatment with PI3K inhibitors 3-MA or wortmannin, as well as knockdown of Beclin 1 expression, was unable to affect autophagic responses mediated by proteasome inhibitors. Overexpression of Beclin 1 enhanced proteasome inhibitor–mediated cytotoxicity of thyroid cancer cells via suppression of survivin. Conclusions: Proteasome inhibitors cause Beclin 1–independent macroautophagic responses of thyroid cancer cells in a Beclin 1–independent manner. Beclin 1 possesses autophagy-independent antitumoral effects upon exposure of thyroid cancer cells to proteasome inhibitors.
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Hwang, Hui-Yun, Yoon Sun Cho, Jin Young Kim, Ki Na Yun, Jong Shin Yoo, Eunhyeong Lee, Injune Kim, and Ho Jeong Kwon. "Autophagic Inhibition via Lysosomal Integrity Dysfunction Leads to Antitumor Activity in Glioma Treatment." Cancers 12, no. 3 (February 27, 2020): 543. http://dx.doi.org/10.3390/cancers12030543.
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Manipulating autophagy is a promising strategy for treating cancer as several autophagy inhibitors are shown to induce autophagic cell death. One of these, autophagonizer (APZ), induces apoptosis-independent cell death by binding an unknown target via an unknown mechanism. To identify APZ targets, we used a label-free drug affinity responsive target stability (DARTS) approach with a liquid chromatography/tandem mass spectrometry (LC–MS/MS) readout. Of 35 protein interactors, we identified Hsp70 as a key target protein of unmodified APZ in autophagy. Either APZ treatment or Hsp70 inhibition attenuates integrity of lysosomes, which leads to autophagic cell death exhibiting an excellent synergism with a clinical drug, temozolomide, in vitro, in vivo, and orthotropic glioma xenograft model. These findings demonstrate the potential of APZ to induce autophagic cell death and its development to combinational chemotherapeutic agent for glioma treatment. Collectively, our study demonstrated that APZ, a new autophagy inhibitor, can be used as a potent antitumor drug candidate to get over unassailable glioma and revealed a novel function of Hsp70 in lysosomal integrity regulation of autophagy.
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Born, Ella J., Sara V. Hollins, and Sarah A. Holstein. "Evaluation of Autophagy Modulators and Isoprenoid Biosynthetic Pathway Inhibitors in Multiple Myeloma Cells." Blood 118, no. 21 (November 18, 2011): 2488. http://dx.doi.org/10.1182/blood.v118.21.2488.2488.
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Abstract Abstract 2488 The production of monoclonal protein (MP) by malignant plasma cells is a hallmark of multiple myeloma (MM). We have previously demonstrated that select inhibitors of the isoprenoid biosynthetic pathway (IBP) which diminish Rab geranylgeranylation, disrupt MP trafficking in MM cells. The resulting intracellular accumulation of MP leads to induction of the unfolded protein response (UPR) pathway and apoptosis. The proteasome-mediated ER-associated degradation pathway has been shown to play an important role in intracellular degradation of monoclonal protein. Autophagy, another cellular process by which proteins are degraded, has been shown to play a role in clearing toxic aggregrated proteins in other systems. The extent to which autophagy is involved in clearing accumulated intracellular MP is unknown. We hypothesized that disruption of autophagy may enhance the cytotoxic effects of agents which impair MP trafficking. We therefore evaluated the effects of combining IBP and autophagy inhibitors in MM cells. Studies were performed in the lambda-light chain secreting RPMI-8226 (RPMI) MM line and the amyloidogenic lambda light chain-secreting ALMC-2 line. IBP inhibitors (IBPIs) included lovastatin (Lov) (HMG-CoA reductase inhibitor), digeranyl bisphosphonate (DGBP) (geranylgeranyl diphosphate synthase inhibitor), and 3-PEHPC (3P) (geranylgeranyl transferase II inhibitor). Autophagy modulators included bafilomycin A (Baf), 3-methyladenine (3-MA), and chloroquine (Chl). MTT cytotoxicity assays demonstrated differential effects when IBP and autophagy inhibitors were combined. Isobologram analysis revealed a synergistic interaction between Lov and Baf while predominantly additive or antagonistic interactions were observed with the combination of Lov and 3MA. A primarily additive interaction was observed between DGBP and Baf in the RPMI cells, while a synergistic effect was observed in the ALMC-2 cells. While concurrent incubation between 3P and Baf resulted in an additive interaction, pre-treatment with 3P for 24 h, followed by co-treatment with Baf for an additional 24 h, yielded a synergistic interaction. ELISA studies were performed to determine the effects of the autophagy modulators on MP trafficking. Treatment with Baf resulted in a concentration-dependent increase in intracellular MP level. Furthermore, addition of Baf potentiated the Lov-, DGBP-, or 3P-induced accumulation of intracellular MP. Neither 3-MA nor chloroquine increased intracellular MP levels by more than 20% and significant potentiation was not seen when these agents were combined with an IBPI. Finally, addition of the proteasome inhibitor bortezomib to the combination of Lov and Baf further increased intracellular MP levels. To evaluate the effects of combining IBPIs with autophagy inhibitors on autophagolysosome formation, studies were performed utilizing acridine orange staining and flow cytometric analysis. The shift from green to red fluorescence, a marker for acidic vesicular organelle (AVO) formation, was determined. These studies demonstrated that the select IBP inhibitors (DGBP and 3P to a greater extent than Lov) enhanced the Baf- and 3-MA-induced decrease in mean red:green fluorescence ratio. To determine whether Baf altered the ability of Lov to induce markers of the UPR, quantitative real time PCR studies were performed. These studies revealed that both Lov and Baf induce the upregulation of components of the UPR including PERK, IRE1, and GADD153. The combination of Lov and Baf further upregulated these UPR components compared with either agent alone. In conclusion, these studies demonstrate that the combination of the autophagy inhibitor Baf and select IBPIs results in enhancement of cytotoxic effects, disruption of MP trafficking, induction of components of the UPR, and inhibition of AVO formation. Further studies will be required to determine the extent to which autophagy regulates MP homeostasis, the mechanism underlying the differential effects of the autophagy inhibitors, and the effect of Rab inhibitors on autophagic processes in MM cells. This work forms the basis for future pre-clinical and clinical studies investigating the combination of inhibitors of MP secretion and autophagy in MM and related disorders. Disclosures: No relevant conflicts of interest to declare.
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Chiou, Shiun-Kwei, Neil Hoa, Lisheng Ge, and Martin R. Jadus. "Nutrient Availability Alters the Effect of Autophagy on Sulindac Sulfide-Induced Colon Cancer Cell Apoptosis." Gastroenterology Research and Practice 2012 (2012): 1–9. http://dx.doi.org/10.1155/2012/897678.
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Autophagy is a catabolic process by which a cell degrades its intracellular materials to replenish itself. Induction of autophagy under various cellular stress stimuli can lead to either cell survival or cell death via apoptotic and/or autophagic (nonapoptotic) pathways. The NSAID sulindac sulfide induces apoptosis in colon cancer cells. Here, we show that inhibition of autophagy under serum-deprived conditions resulted in significant reductions of sulindac sulfide-induced apoptosis in HT-29 colon cancer cells. In contrast, inhibition of autophagy under conditions where serum is available significantly increased sulindac sulfide-induced apoptosis in HT-29 cells. We previously showed that the apoptosis inhibitor, survivin, plays a role in regulating NSAID-induced apoptosis and autophagic cell death. Here, we show that survivin protein half-life is increased in the presence of autophagy inhibitors under serum-deprived conditions, but not under conditions when serum is available. Thus, the increased levels of survivin may be a factor contributing to inhibition of sulindac sulfide-induced apoptosis under serum-deprived conditions. These results suggest that whether a cell lives or dies due to autophagy induction depends on the balance of factors that regulate both autophagic and apoptotic processes.
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Stalnecker, Clint A., Kajal R. Grover, A. Cole Edwards, Michael F. Coleman, Runying Yang, Jonathan M. DeLiberty, Björn Papke, et al. "Concurrent Inhibition of IGF1R and ERK Increases Pancreatic Cancer Sensitivity to Autophagy Inhibitors." Cancer Research 82, no. 4 (December 17, 2021): 586–98. http://dx.doi.org/10.1158/0008-5472.can-21-1443.
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Abstract The aggressive nature of pancreatic ductal adenocarcinoma (PDAC) mandates the development of improved therapies. As KRAS mutations are found in 95% of PDAC and are critical for tumor maintenance, one promising strategy involves exploiting KRAS-dependent metabolic perturbations. The macrometabolic process of autophagy is upregulated in KRAS-mutant PDAC, and PDAC growth is reliant on autophagy. However, inhibition of autophagy as monotherapy using the lysosomal inhibitor hydroxychloroquine (HCQ) has shown limited clinical efficacy. To identify strategies that can improve PDAC sensitivity to HCQ, we applied a CRISPR-Cas9 loss-of-function screen and found that a top sensitizer was the receptor tyrosine kinase (RTK) insulin-like growth factor 1 receptor (IGF1R). Additionally, reverse phase protein array pathway activation mapping profiled the signaling pathways altered by chloroquine (CQ) treatment. Activating phosphorylation of RTKs, including IGF1R, was a common compensatory increase in response to CQ. Inhibition of IGF1R increased autophagic flux and sensitivity to CQ-mediated growth suppression both in vitro and in vivo. Cotargeting both IGF1R and pathways that antagonize autophagy, such as ERK–MAPK axis, was strongly synergistic. IGF1R and ERK inhibition converged on suppression of glycolysis, leading to enhanced dependence on autophagy. Accordingly, concurrent inhibition of IGF1R, ERK, and autophagy induced cytotoxicity in PDAC cell lines and decreased viability in human PDAC organoids. In conclusion, targeting IGF1R together with ERK enhances the effectiveness of autophagy inhibitors in PDAC. Significance: Compensatory upregulation of IGF1R and ERK–MAPK signaling limits the efficacy of autophagy inhibitors chloroquine and hydroxychloroquine, and their concurrent inhibition synergistically increases autophagy dependence and chloroquine sensitivity in pancreatic ductal adenocarcinoma.
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Li, Guishuang, Hongming Rao, and Weihong Xu. "Puerarin plays a protective role in chondrocytes by activating Beclin1-dependent autophagy." Bioscience, Biotechnology, and Biochemistry 85, no. 3 (December 31, 2020): 621–25. http://dx.doi.org/10.1093/bbb/zbaa078.
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ABSTRACT Puerarin can protect chondrocytes, whereby ameliorating osteoarthritis. Puerarin also promotes autophagy. Autophagy maintains chondrocyte homeostasis. The role of autophagy in puerarin-protected chondrocytes is unknown. Puerarin promoted chondrocyte autophagy. Puerarin-protected chondrocytes were reversed by autophagy inhibitors and Beclin1 inhibitor. 3-MA or Beclin1 inhibitor in vivo reversed puerarin-ameliorated cartilage damage of osteoarthritis mice. Thus, puerarin can protect chondrocytes through Beclin1-dependent autophagy activation.
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Fan, Lihua, Deyuan Chen, Jianping Wang, Yini Wu, Dongli Li, and Xiaoyan Yu. "Sevoflurane Ameliorates Myocardial Cell Injury by Inducing Autophagy via the Deacetylation of LC3 by SIRT1." Analytical Cellular Pathology 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/6281285.
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Misfolded and aberrant proteins have been found to be associated with myocardial cell injury. Thus, increased clearance of misfolded or aggregated proteins via autophagy might be a potential option in preventing myocardial cell injury. Sevoflurane may ameliorate myocardial cell injury by affecting sirtuin 1- (SIRT1-) mediated autophagy. Rat models with myocardial cell injury were induced by limb ischemia reperfusion. The model rats received different treatments: sevoflurane, nicotinamide, and autophagy inhibitor 3-methyladenine (3-MA). Autophagy was observed by SEM. The levels of SIRT1 and microtubule-associated protein 1A/1B-light chain 3 (LC3) were measured. Present findings demonstrated that limb ischemia reperfusion induced autophagy. Sevoflurane increased the level of SIRT1, which deacetylated LC3 and further increased autophagic rates. On the other hand, the autophagy was inhibited by sevoflurane and or the inhibitors of SIRT1 and LC3. Present results demonstrated a novel molecular mechanism by which sevoflurane induced autophagy by increasing the level of SIRT1 and reducing the acetylation of LC3.
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Salminen, Antero, Juha M. T. Hyttinen, Anu Kauppinen, and Kai Kaarniranta. "Context-Dependent Regulation of Autophagy by IKK-NF-κB Signaling: Impact on the Aging Process." International Journal of Cell Biology 2012 (2012): 1–15. http://dx.doi.org/10.1155/2012/849541.
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The NF-κB signaling system and the autophagic degradation pathway are crucial cellular survival mechanisms, both being well conserved during evolution. Emerging studies have indicated that the IKK/NF-κB signaling axis regulates autophagy in a context-dependent manner. IKK complex and NF-κB can enhance the expression of Beclin 1 and other autophagy-related proteins and stimulate autophagy whereas as a feedback response, autophagy can degrade IKK components. Moreover, NF-κB signaling activates the expression of autophagy inhibitors (e.g., A20 and Bcl-2/xL) and represses the activators of autophagy (BNIP3, JNK1, and ROS). Several studies have indicated that NF-κB signaling is enhanced both during aging and cellular senescence, inducing a proinflammatory phenotype. The aging process is also associated with a decline in autophagic degradation. It seems that the activity of Beclin 1 initiation complex could be impaired with aging, since the expression of Beclin 1 decreases as does the activity of type III PI3K. On the other hand, the expression of inhibitory Bcl-2/xL proteins increases with aging. We will review the recent literature on the control mechanisms of autophagy through IKK/NF-κB signaling and emphasize that NF-κB signaling could be a potent repressor of autophagy with ageing.
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Avsec, Damjan, Alma Tana Jakoš Djordjevič, Maša Kandušer, Helena Podgornik, Matevž Škerget, and Irena Mlinarič-Raščan. "Targeting Autophagy Triggers Apoptosis and Complements the Action of Venetoclax in Chronic Lymphocytic Leukemia Cells." Cancers 13, no. 18 (September 10, 2021): 4557. http://dx.doi.org/10.3390/cancers13184557.
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Continuous treatment of patients with chronic lymphocytic leukemia (CLL) with venetoclax, an antagonist of the anti-apoptotic protein Bcl-2, can result in resistance, which highlights the need for novel targets to trigger cell death in CLL. Venetoclax also induces autophagy by perturbing the Bcl-2/Beclin-1 complex, so autophagy might represent a target in CLL. Diverse autophagy inhibitors were assessed for cytotoxic activities against patient-derived CLL cells. The AMPK inhibitor dorsomorphin, the ULK1/2 inhibitor MRT68921, and the autophagosome–lysosome fusion inhibitor chloroquine demonstrated concentration-dependent and time-dependent cytotoxicity against CLL cells, even in those from hard-to-treat patients who carried del(11q) and del(17p). Dorsomorphin and MRT68921 but not chloroquine triggered caspase-dependent cell death. According to the metabolic activities of CLL cells and PBMCs following treatments with 10 µM dorsomorphin (13% vs. 84%), 10 µM MRT68921 (7% vs. 78%), and 25 µM chloroquine (41% vs. 107%), these autophagy inhibitors are selective toward CLL cells. In these CLL cells, venetoclax induced autophagy, and addition of dorsomorphin, MRT68921, or chloroquine showed potent synergistic cytotoxicities. Additionally, MRT68921 alone induced G2 arrest, but when combined with venetoclax, it triggered caspase-dependent cytotoxicity. These data provide the rationale to target autophagy and for autophagy inhibitors as potential treatments for patients with CLL.
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Yin, Wei, Jianfeng Xu, and Yanjiao Mao. "Synergistic effects of autophagy inhibitors combined with cisplatin against cisplatin-resistant nasopharyngeal cancer cells." Biochemistry and Cell Biology 99, no. 3 (June 2021): 322–29. http://dx.doi.org/10.1139/bcb-2020-0283.
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This study explored the synergistic effects of autophagy inhibitors combined with cisplatin against cisplatin-resistant nasopharyngeal cancer cells by treating HNE-1 and cisplatin (diamminedichloroplatinum; DDP)-resistant HNE1/DDP nasopharyngeal cancer cell lines with DDP, autophagy inhibitors, or a combination of autophagy inhibitors and DDP. Cell viability was determined via MTT (colorimetric) and colony-forming assays, and the rate of apoptosis was determined using propidium iodide (PI) and annexin V double-staining. The expressions of proteins were determined by Western blotting. For our in-vivo studies, a murine xenograft model was established to evaluate the anti-tumor effects of the combination of autophagy inhibitor and DDP. The results showed that treatment with DDP increased the expressions of ATP-binding cassette sub-family B member 1 (ABCB1), ATP Binding Cassette Subfamily C Member 1 (ABCC1), and P-glycoprotein 1 (P-gp) in the HNE1/DDP cell lines. Treatment with chloroquine decreased the expression levels of ABCB1, ABCC1, and P-gp, and increased the formation of LC3-II and the expression levels of p62 in the HNE1/DDP cells. Additionally, the combination of autophagy inhibitors and DDP produced a synergistic effect on DDP-induced cell death and apoptosis. Furthermore, the combination of the autophagy inhibitor and DDP showed significant anti-tumor effects in the xenograft mouse model. In summary, autophagy inhibitors show synergistic anti-tumor effects with DDP in vitro against DDP-resistant nasopharyngeal cancer cells and in vivo in our xenograft murine model.
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Wang, Xi-Mei, Yue-Jin Yang, Yong-Jian Wu, Qian Zhang, and Hai-Yan Qian. "Attenuating Hypoxia-Induced Apoptosis and Autophagy of Mesenchymal Stem Cells: the Potential of Sitagliptin in Stem Cell-Based Therapy." Cellular Physiology and Biochemistry 37, no. 5 (2015): 1914–26. http://dx.doi.org/10.1159/000438552.
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Background/Aims: Dipeptidyl peptidase-4 (DPP-4) inhibitors have pleiotropic effects on cardiovascular protection beyond the antidiabetic property. However, it remains unknown that the impact of one DPP-4 inhibitor sitagliptin on the survival of mesenchymal stem cells (MSCs) in hypoxia and serum deprivation (H/SD) environment. Methods: The apoptosis and autophagy of MSCs were analyzed in different concentrations of sitagliptin under H/SD condition. For later studies, we tested the relationship between anti-apoptotic and anti-autophagic effects of sitagliptin. The level of cell apoptosis was analyzed by Annexin V-FITC/PI staining, western blot of Bcl-2 and Bax proteins. Autophagy flux was assessed by multiple autophagy related proteins and substrates. Cell autophagy was identified by acridine orange staining, western blot of Beclin 1 and light chain 3 protein, and transmission electron microscopy. Results: We demonstrated that sitagliptin attenuated hypoxia-induced apoptosis and autophagy of MSCs. Furthermore, sitagliptin regulated cell autophagy by Bcl-2/ Beclin 1 pathway in H/SD condition. Conclusions: This study provides insight into the utility of the DPP-4 inhibitor sitagliptin for MSCs transplantation in the ischemic microenvironment that extends its antidiabetic property.
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Shen, John P., Sanjay Divakaran, Letian Kuai, Xiang Wang, Shao-En Ong, Ravi Amaravadi, John Wood, et al. "Autophagy as a Target Pathway in Multiple Myeloma: A Forward Chemical Genetic Approach." Blood 110, no. 11 (November 16, 2007): 2510. http://dx.doi.org/10.1182/blood.v110.11.2510.2510.
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Abstract Autophagy is an evolutionarily conserved process by which cellular structures may be degraded to support ongoing biogenesis. Recent evidence has identified the induction of autophagy following growth factor pathway inhibition, rapid tumor expansion and proteasome inhibition. Thus, autophagy is a highly desirable pathway for the development of targeted therapeutics in cancer, in particular in tumors characterized by misfolded protein stress such as multiple myeloma (MM). Unfortunately, there are only several known classes of autophagy inhibitors and the emerging biology of autophagy has identified few validated targets. We therefore performed a forward chemical genetic study of autophagy using novel techniques in high-content imaging, high-throughput screening and multidimensional data analysis. Using LN229 glioblastoma cells stably transfected with an LC3-EGFP construct, we created a robust screening platform capable of quantifying the number, size and fluorescence intensity of autophagosomes. Assay validation was performed with the known autophagy inhibitor chloroquine, which induces a characteristic shift from diffuse to punctate fluorescence. Initially, we profiled a library of approximately 3,500 structurally diverse bioactive small molecules to leverage possible downstream mechanistic insights. Assay positives and controls were re-tested in the adherent H1299 adenocarcinoma cell line likewise stably expressing LC3-EGFP. Known autophagy inhibitors were enriched with this approach: nocodazole, bafilomycin A1, colchicine and monensin. Structure-activity relationship analysis of the primary screening data and 34 novel autophagy modulators revealed a compelling activity of bis-indolyl maleimides. We confirmed sub-micromolar inhibition of autophagy by three such compounds using a quantitative, radiolabeled protein degradation assay (tritiated tyrosine pulse-chase), LC3-II immunoblotting and quantitative measurement of autophagosomes across three cell lines. From these studies we selected a lead compound, K252a, for further characterization and tested twenty-two closely related analogues. Detailed SAR analysis has identified features of the molecule required for inhibition of autophagy and sites permissive for further functionalization in ongoing target identification studies. Using MM as a translational model system of misfolded protein stress, we found dose-dependent, selective cytotoxicity in MM of K252a compared to analogues lacking autophagy inhibitory activity. We report here the results of a forward chemical genetic study of autophagy which identifies and characterizes novel small molecule inhibitors of autophagy and establishes a rationale for clinical studies of autophagy inhibitors in the treatment of MM.
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Landowski, Terry H., Aluvia M. Escalante, Andrew Jefferson, Robert T. Dorr, and Ronald Lynch. "Inhibition of Autophagy Promotes Bortezomib-Mediated Cell Death in Myeloma Cells." Blood 112, no. 11 (November 16, 2008): 3677. http://dx.doi.org/10.1182/blood.v112.11.3677.3677.
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Abstract The 26S proteasome is a key regulator of proteins controlling many important cellular functions, including cell cycle progression, differentiation, gene transcription and apoptosis. Proteasome inhibition is a new therapeutic strategy that has shown promise in the treatment of B cell malignancies, primarily multiple myeloma. We and others have demonstrated that proteasome inhibitors induce endoplasmic reticulum (ER) stress and activate an unfolded protein response (UPR) in transformed cells. Our previous work demonstrated that bortezomib induces an endoplasmic reticulum (ER) stress response ultimately leading to calcium-dependent apoptotic cell death. Co-treatment of myeloma cells with the mitochondrial uniporter inhibitor ruthenium red (RuR) abrogated bortezomib mediated cell death, indicating that the cytotoxic effects of proteasomal inhibition requires dysregulation of intracellular Ca2+. Intracellular Ca2+ has also been implicated in the cellular stress response known as autophagy or “self-eating”. Macroautophagy (hereafter referred to as autophagy) is induced by various cellular stresses including nutrient deprivation, metabolic insufficiency, interruption of growth factor signaling, elevated ROS, accumulation of intracellular Ca2+, and the UPR. The biochemical events linking the cellular stress response with the induction of autophagy, and the relationship between autophagy and apoptosis is not well understood. In this study, we investigate the role of the Ca2+ dependent serine protease, calpain, as a mediator of the conversion from autophagic cell survival to accelerated cell death in the ER stress response. We demonstrate that the proteasome inhibitor, bortezomib, initiates autophagy in myeloma cells, and protection from bortezomib-mediated cell death by mitochondrial Ca2+ inhibitors is associated with a promotion and stabilization of the autophagosome. This response can be reversed, and indeed, accelerated, leading to enhanced cell death, by blockade of calpain activity. Inhibition of calpain activity with the tri-peptide zLLY-FMK (Calpain Inhibitor IV, (CiIV) or the non-peptide inhibitor, PD150606, demonstrated a significant increase in the cytotoxic activity of bortezomib. Similarly, elimination of the small catalytic subunit, CAPNS1, using siRNA, enhanced bortezomib-mediated cell death, and prevented autophagosome-lysosomal progression. Furthermore, inhibition of calpain by clinically approved HIV protease inhibitors including Nelfinavir, Ritonavir, Saquinavir, and Indinavir sulfate, significantly increased the cytotoxic activity of bortezomib in vitro. We suggest that disregulation of Ca2+ by bortezomib-mediated ER stress activates the autophagic survival response. Inhibition of mitochondrial Ca2+ uptake by the uniporter inhibitor RuR promotes autophagy, and confers resistance to bortezomib. Conversely, inhibition of the Ca2+-dependent serine protease, calpain, prevents autophagolysosome maturation, and subverts the survival response to cell death. These data are likely to have important clinical implications for the treatment of refractory myeloma and other B cell malignancies.
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Robke, Lucas, Yushi Futamura, Georgios Konstantinidis, Julian Wilke, Harumi Aono, Zhwan Mahmoud, Nobumoto Watanabe, et al. "Discovery of the novel autophagy inhibitor aumitin that targets mitochondrial complex I." Chemical Science 9, no. 11 (2018): 3014–22. http://dx.doi.org/10.1039/c7sc05040b.
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Phenotypic screening for autophagy inhibitors followed by target identification resulted in the discovery of aumitin, a new autophagy inhibitor that inhibits mitochondrial respiration by targeting complex I.
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Bagamanshina, Anastasia V., Olga S. Troitskaya, Anna A. Nushtaeva, Anastasia Yu Yunusova, Marina O. Starykovych, Elena V. Kuligina, Yuri Ya Kit, et al. "Cytotoxic and Antitumor Activity of Lactaptin in Combination with Autophagy Inducers and Inhibitors." BioMed Research International 2019 (June 17, 2019): 1–16. http://dx.doi.org/10.1155/2019/4087160.
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Autophagy is a degradative process in which cellular organelles and proteins are recycled to restore homeostasis and cellular metabolism. Autophagy can be either a prosurvival or a prodeath process and remains one of the most fundamental processes for cell vitality. Thus autophagy modulation is an important approach for reinforcement anticancer therapeutics. Earlier we have demonstrated that recombinant analog of human milk protein lactaptin (RL2) induced apoptosis of various cultured cancer cells and activated lipidation of microtubule-associated protein 1 light chain 3 (LC3). In this study we investigated whether autophagy inhibitors—chloroquine (CQ), Ku55933 (Ku), and 3-methyladenine (3MA)—or inducer—rapamycin (Rap)—can enhance cytotoxic activity of lactaptin analog in cancer cells and its anticancer activity in the mice model. Western Blot analysis revealed that RL2 induced short-term autophagy in MDA-MB-231 and MCF-7 cells at early stages of incubation and that these data were confirmed by the transmission electron microscopy of autophagosome/autophagolysosome formation. RL2 stimulates reactive oxygen species (ROS) production, autophagosomes accumulation, upregulation of ATG5 with processing of LC3I to LC3II, and downregulation of p62/sequestosome 1 (p62). We have shown that autophagy modulators, CQ, Ku, and Rap, synergistically increased cytotoxicity of RL2, and RL2 with CQ induced autophagic cell death. In addition, CQ, Ku, and Rap in combination with RL2 decreased activity of lysosomal protease Cathepsin D. More importantly, combining RL2 with CQ, we improved antitumor effect in mice. Detected synergistic cytotoxic effects of both types of autophagy regulators, inhibitors, and inducers with RL2 against cancer cells allow us to believe that these combinations can be a basis for the new anticancer approach. Finally, we suppose that CQ and Rap promoting of short-term RL2-induced autophagy interlinks with final autophagic cell death.
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Payne, Claire M., Cheray Crowley-Skillicorn, Hana Holubec, Katerina Dvorak, Carol Bernstein, Mary Pat Moyer, Harinder Garewal, and Harris Bernstein. "Deoxycholate, an Endogenous Cytotoxin/Genotoxin, Induces the Autophagic Stress-Survival Pathway: Implications for Colon Carcinogenesis." Journal of Toxicology 2009 (2009): 1–14. http://dx.doi.org/10.1155/2009/785907.
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We report that deoxycholate (DOC), a hydrophobic bile acid associated with a high-fat diet, activates the autophagic pathway in non-cancer colon epithelial cells (NCM-460), and that this activation contributes to cell survival. The DOC-induced increase in autophagy was documented by an increase in autophagic vacuoles (detected using transmission electron microscopy, increased levels of LC3-I and LC3-II (western blotting), an increase in acidic vesicles (fluorescence spectroscopy of monodansycadaverine and lysotracker red probes), and increased expression of the autophagic protein, beclin-1 (immunohistochemistry/western blotting). The DOC-induced increase in beclin-1 expression was ROS-dependent. Rapamycin (activator of autophagy) pre-treatment of NCM-460 cells significantly (P<.05) decreased, and 3-MA (inhibitor of autophagy) significantly (P<.05) increased the cell loss caused by DOC treatment, alone. Rapamycin pre-treatment of the apoptosis-resistant colon cancer cell line, HCT-116RC (developed in our laboratory), resulted in a significant decrease in DOC-induced cell death. BafilomycinA1and hydroxychloroquine (inhibitors of the autophagic process) increased the DOC-induced percentage of apoptotic cells in HCT-116RC cells. It was concluded that the activation of autophagy by DOC has important implications for colon carcinogenesis and for the treatment of colon cancer in conjunction with commonly used chemotherapeutic agents.
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Zhang, Yanlin, Ying Xie, Shoujiang You, Qiao Han, Yongjun Cao, Xia Zhang, Guodong Xiao, Rui Chen, and Chunfeng Liu. "Autophagy and Apoptosis in the Response of Human Vascular Endothelial Cells to Oxidized Low-Density Lipoprotein." Cardiology 132, no. 1 (2015): 27–33. http://dx.doi.org/10.1159/000381332.
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Objectives: Oxidized low-density lipoprotein (ox-LDL) may induce autophagy, apoptosis, necrosis or proliferation of cultured endothelial cells depending on the concentration and exposure time. Our previous studies found that ox-LDL exposure for 6 h increases the autophagic level of human umbilical vein endothelial cells (HUVECs) in a concentration-dependent manner. The present study investigates the relationship between autophagy and apoptosis in HUVECs exposed to ox-LDL. Methods: Flow cytometry and Western blot were used to study the apoptotic and autophagic phenomena. The contribution of autophagic and apoptotic mechanisms to ox-LDL-induced upregulation of MAP1-LC3, beclin1 and p53 protein levels were assessed by pretreatment with the autophagic inhibitors 3-MA and Atg5 small interfering (si)RNA, as well as z-vad-fmk, an apoptosis inhibitor. Results: ox-LDL induced the apoptosis of HUVECs in a concentration-dependent way. The increased expression of the autophagic proteins, LC3-II and beclin1, can be reversed by 3-MA and z-vad-fmk pretreatment. 3-MA and Atg5 siRNA increased the ox-LDL-induced increases of the p53 protein level and the annexin V-positive staining, which was decreased by z-vad-fmk. Conclusion: These results suggest that overstimulation of ox-LDL can induce autophagy and apoptosis in HUVECs. Inhibition of apoptosis leads to an inhibition of autophagy induced by ox-LDL. However, inhibition of autophagy leads to an increase in the ox-LDL-induced apoptosis.
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Zachari, Maria, Julie M. Rainard, George C. Pandarakalam, Lindsay Robinson, Jonathan Gillespie, Muralikrishnan Rajamanickam, Veronique Hamon, Angus Morrison, Ian G. Ganley, and Stuart P. McElroy. "The identification and characterisation of autophagy inhibitors from the published kinase inhibitor sets." Biochemical Journal 477, no. 4 (February 27, 2020): 801–14. http://dx.doi.org/10.1042/bcj20190846.
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Autophagy is a critical cellular homeostatic mechanism, the dysfunction of which has been linked to a wide variety of disease states. It is regulated through the activity of specific kinases, in particular Unc-51 like autophagy activating kinase 1 (ULK1) and Phosphatidylinositol 3-kinase vacuolar protein sorting 34 (VPS34), which have both been suggested as potential targets for drug development. To identify new chemical compounds that might provide useful chemical tools or act as starting points for drug development, we screened each protein against the Published Kinase Inhibitor Set (PKIS), a library of known kinase inhibitors. In vitro screening and analysis of the published selectivity profiles of the hits informed the selection of three relatively potent ATP-competitive inhibitors against each target that presented the least number of off-target kinases in common. Cellular assays confirmed potent inhibition of autophagy in response to two of the ULK1 inhibitors and all three of the VPS34 inhibitors. These compounds represent not only a new resource for the study of autophagy but also potential chemical starting points for the validation or invalidation of these two centrally important autophagy kinases in disease models.
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Chen, Hua, Liyang Chen, Biao Cheng, and Chaoyin Jiang. "Cyclic Mechanical Stretching Induces Autophagic Cell Death in Tenofibroblasts Through Activation of Prostaglandin E2 Production." Cellular Physiology and Biochemistry 36, no. 1 (2015): 24–33. http://dx.doi.org/10.1159/000374050.
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Background/Aims: Autophagic cell death has recently been implicated in the pathophysiology of tendinopathy. Prostaglandin E2 (PGE2), a known inflammatory mediator of tendinitis, inhibits tenofibroblast proliferation in vitro; however, the underlying mechanism is unclear. The present study investigated the relationship between PGE2 production and autophagic cell death in mechanically loaded human patellar tendon fibroblasts (HPTFs) in vitro. Methods: Cultured HPTFs were subjected to exogenous PGE2 treatment or repetitive cyclic mechanical stretching. Cell death was determined by flow cytometry with acridine orange/ethidium bromide staining. Induction of autophagy was assessed by autophagy markers including the formation of autophagosomes and autolysosomes (by electron microscopy, AO staining, and formation of GPF-LC3-labeled vacuoles) and the expression of LC3-II and BECN1 (by western blot). Stretching-induced PGE2 release was determined by ELISA. Results: Exogenous PGE2 significantly induced cell death and autophagy in HPTFs in a dose-dependent manner. Blocking autophagy using inhibitors 3-methyladenine and chloroquine, or small interfering RNAs against autophagy genes Becn-1 and Atg-5 prevented PGE2-induced cell death. Cyclic mechanical stretching at 8% and 12% magnitudes for 24 h significantly stimulated PGE2 release by HPTFs in a magnitude-dependent manner. In addition, mechanical stretching induced autophagy and cell death. Blocking PGE2 production using COX inhibitors indomethacin and celecoxib significantly reduced stretching-induced autophagy and cell death. Conclusion: Taken together, cyclic mechanical stretching induces autophagic cell death in tenofibroblasts through activation of PGE2 production.
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Qiu, Shaowei, Andrew J. Paterson, Ajay Abraham, Jianbo He, Mansi Shah, Puneet Agarwal, Amanda K. Mullen, et al. "Role of Enhanced Autophagy in Resistance of FLT3-ITD AML Stem Cells to FLT3 TKI Treatment." Blood 132, Supplement 1 (November 29, 2018): 1358. http://dx.doi.org/10.1182/blood-2018-99-115702.
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Abstract The FLT3-ITD mutation occurs in 25-30% of AML patients, and is associated with increased relapse rate and poor survival. FLT3 tyrosine kinase inhibitors (TKI) have shown encouraging results, but responses are not sustained in most patients. Therefore there is considerable interest in understanding mechanism contributing to resistance and preservation of FLT3-ITD AML stem cells after TKI treatment. Autophagy is an important cellular response that maintains cell survival under stress. Here we investigated the regulation of autophagy in FLT3-ITD+ AML cells, and its role in resistance to FLT3 TKI treatment. Expression of a FLT3-ITD construct in FLT3-ITD negative OCI-AML3 cells using lentiviral vectors resulted in increased autophagic flux compared with wild-type FLT3 or non-transduced controls. However, treatment of FLT3-ITD+ MV4-11 and Molm13 AML cells, or primary FLT3-ITD+ CD34+ cells, with the potent FLT3 TKI AC220 (Quizartinib) did not significantly alter autophagic flux. These results suggest that FLT3-ITD expression increases autophagy but in a kinase-independent manner. MV4-11 and Molm13 cells were transduced with the GFP-LC3-RFP-LC3 ΔG construct (Kaizuka T, et al,2016) to measure autophagic flux. Autophagyhigh AML cells showed lower growth rate compared with Autophagylow cells (0.65, p=0.025), and reduced sensitivity to inhibition by AC220 (0.49 vs 0.71, p=0.003). Treatment of MV4-11 and Molm13 cells with the potent autophagy inhibitor Lys05 in combination with AC220 resulted in significantly enhanced inhibition of AML cell growth (MV4-11: 0.83 vs 0.54, p<0.001; Molm13: 0.58 vs 0.43, p=0.02) and increased induction of apoptosis (MV4-11: 0.81 vs 0.54, p<0.001; Molm13: 0.73 vs 0.49, p=0.024) compared to AC220 alone. We further show that inhibition of autophagy by shRNA-mediated knockdown of the critical autophagy gene ATG5 enhanced sensitivity of AML cells to AC220 treatment (MV4-11: 0.91 vs 0.65, p=0.005; Molm13: 0.88 vs 0.64, p=0.004). Treatment with Lys05 also inhibited autophagic flux in primary FLT3-ITD+ AML CD34+ stem/progenitor cells and resulted in significantly increased inhibition of cell cycle arrest (G0 stage: 40.3% vs 61.8%), increased myeloid differentiation (CD11b: 1 vs 1.24, p=0.009; CD14: 1 vs 1.21, p=0.0024), and increased cell death when combined with AC220 (0.58% vs 0.78%, p=0.0245). These results indicate that increased autophagy in FLT3-ITD+ AML cells is associated with TKI resistance, and that autophagy inhibition enhances sensitivity of FLT3-ITD+ AML cells to TKI treatment. Induction of autophagy by starvation or mTOR inhibitor treatment in MOLM13 and MV4-11 cells was associated with reduced p53 expression, whereas autophagy inhibition by chloroquine or SAR405, a PIK3C3/Vps34 inhibitor, was associated with increased p53 expression. Starvation-mediated autophagy in FLT3-ITD+ AML cells was significantly increased upon p53 knockdown, suggesting that p53 has an inhibitory effect on autophagy. Enhanced inhibition of FLT3-ITD+ AML cell growth by autophagy inhibition in combination with AC220 treatment was prevented by shRNA-mediated knockdown of p53, suggesting that effects of autophagy inhibition on FLT3-ITD+ AML cell growth were p53 dependent. We conclude that FLT3-ITD expression enhances autophagic flux in FLT3-ITD+ AML cells in a kinase-independent manner, and that increased autophagy contributes to TKI resistance of FLT3-ITD+ AML cells. We show that autophagy inhibition can enhance sensitivity of FLT3-ITD+ AML stem cells to TKI treatment. Finally, we demonstrate important roles for autophagy in regulating p53 levels, and conversely for p53 in regulating autophagy and the effects of autophagy inhibition in FLT3-ITD+ AML cells. These studies support further development of strategies for targeting of autophagy and related pathways to enhance efficacy of TKI treatment in eliminating AML stem cells. Disclosures No relevant conflicts of interest to declare.
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Bradner, James E., John P. Shen, Ethan O. Perlstein, Sanjay Divakaran, Edward F. Greenberg, Ravi Amaravadi, and Stuart L. Schreiber. "Discovery and Characterization of Small Molecule Inhibitors of Autophagy for Cancer Therapy." Blood 108, no. 11 (November 16, 2006): 2606. http://dx.doi.org/10.1182/blood.v108.11.2606.2606.
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Abstract Autophagy is an evolutionarily conserved process by which cellular structures may be degraded for ongoing biogenesis. Following nutrient deprivation, autophagy functions critically to replenish metabolic precursors by recycling nonessential structures. Recent evidence has identified the induction of autophagy following growth factor withdrawal in preclinical models of cancer. As the autophagic response in these studies requires abrogation of apoptotic effectors, autophagy emerges as a relevant cell survival mechanism in human cancer. While growth factor depletion is an uncommon approach in cancer therapy, small molecule inhibition of dominant growth factor pathways is a central focus of targeted chemotherapeutic development. Therefore, we predicted that small molecule inhibition of growth factor pathways will prompt an autophagic response in human cancers, and that additional inhibition of autophagy will result in a synergistic and tumor-selective cytotoxicity. As there are few known inhibitors of autophagy, we developed a forward chemical genetic discovery approach utilizing high-throughput, high-content, epifluorescent microscopy. A human glioblastoma cell line stably expressing an EGFP-LC3 fusion protein was cultured at low confluency in 384-well plate format. Four hours following 100 nL pin-transfer of an arrayed small molecule library, cells were fixed and nuclei were counter-stained with Hoechst. Images were acquired and analyzed using automated microscopy and scripting software (MetaXPress; Molecular Devices, Sunnyvale, CA). The designed algorithm proved capable of quantitative cell-scoring for the presence of characteristic, fluorescent, LC3-positive autophagic punctae, as well as discrete annotation of vesicle size permitting the differentiation of likely autophagy inducers from inhibitors of autophagosome-lysosome fusion. Statistical rendering of four phenotypic measurements for the selection of assay positives was performed in the ChemBank analysis environment (NCI-Initiative for Chemical Genetics, Cambridge, MA). With an interest in discovering immediate candidates for clinical investigation, we profiled a 3000-member small molecule library of off-patent pharmaceutical products and bioactive compounds with known pharmacology. Six ligands were discovered which demonstrated a phenotype characteristic of late inhibition of autophagosomal maturation. Each is an established pharmaceutical product. At least three of these molecules have previous annotation as inhibitors of vesicle function in the medical literature. With an interest in profiling these ligands for synergy with growth factor pathway inhibitors in cancer, we established a novel platform for assessing synergistic cytotoxicity in high-throughput format. Data collected from these experiments confirm the synergistic antineoplastic activity of known and novel inhibitors of autophagy when combined with receptor tyrosine kinase inhibition in model systems of hematologic and epithelial tumors. These experiments serve as the scientific basis for clinical studies planned in lung cancer, breast cancer and multiple myeloma. Additionally, these data identify a panel of small molecule inducers of autophagy of plausible utility in protein aggregation disorders such as Huntington’s, Parkinson’s and Prion Diseases.
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Chen, Hua, Kyle Potts, Allan Murray, Mary Hitt, and Ron Moore. "Combined inhibition of autophagy with mTOR inhibitor to enhance cell death in renal cell carcinoma." Journal of Clinical Oncology 35, no. 6_suppl (February 20, 2017): 450. http://dx.doi.org/10.1200/jco.2017.35.6_suppl.450.
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450 Background: mTOR (mammalian target of rapamycin) and autophagy are increasingly recognized as being a central cellular and pathological process for numerous human diseases, including renal cell carcinoma (RCC). Depending on the cellular context, autophagy may promote cancer cell survival or cell death. However, little is known about the mechanisms of regulating mTOR activity and autophagic function in RCC. We hypothesize that autophagy promotes cell survival via mTOR mediated-phosphatidylinositol 3-kinase (PI3K)/AKT pathway and is regulated by the von Hippel-Lindau (VHL) tumor suppressor. Methods: RCC cells were stably lentiviral transduced with expression of VHL or mCherry-EGFP tandemfluorescent-tagged LC3B for studying autophagic flux. Cell viability was evaluated by cytotoxic XTT and clonogenic assays and flow cytometry. The efficacy of PI3K/AKT/mTOR pathway inhibition by RAD001, PI-103, MK2206, AZD8055, and/or lysosomotropic inhibitors were evaluated by immunoblots and immunofluorescence for autophagy process of autophagosome and lysosome. Results: We show that mTOR is hyperactive in VHL-deficient cells compared to cells with wild-type VHL or VHL-expressing cells. AZD8055-induced toxicity occurs in a VHL-independent manner via cell cycle arrest and clonogenic senescent cell death, but results in significantly increased expression of autophagic marker LC3-II and the formation of autophagic vacuoles. Pharmacologic inhibition or siRNA silencing of autophagy pathway components promotes AZD8055-induced cell death in VHL-deficient cells. Interestingly, defective autophagy marked by the presence of sustained p62 expression in VHL-deficient cells appears to contribute to cell survival via mTOR signaling, which in turn influences autophagosome-lysosome fusion, and thus controls autophagic flux by acting at the termination stage of the process. Conclusions: These results support mTOR and autophagy pathways as potential targets of anticancer drugs and reveal VHL in control of the autophagic program in RCC. Further, this work suggests that combined inhibition of autophagy along with mTOR inhibitors could be a novel therapeutic strategy for the treatment of RCC.
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Monaci, Sara, Federica Coppola, Daniela Rossi, Gaia Giuntini, Irene Filippi, Giuseppe Marotta, Silvano Sozzani, Fabio Carraro, and Antonella Naldini. "Hypoxia Induces Autophagy in Human Dendritic Cells: Involvement of Class III PI3K/Vps34." Cells 11, no. 10 (May 19, 2022): 1695. http://dx.doi.org/10.3390/cells11101695.
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Hypoxia is a component of both physiological and pathological conditions, including inflammation, solid tumors, and lymphoid tissues, where O2 demand is not balanced by O2 supply. During their lifespan, dendritic cells (DCs) are exposed to different pO2 and activate different adaptive responses, including autophagy, to preserve their viability and functions. Autophagy plays multiple roles in DC physiology. Very recently, we demonstrated that hypoxia shapes autophagy in DCs upon their differentiation state. Here, we proposed a role for PI3Ks, and especially class III PI3K/Vps34, that could be relevant in hypoxia-induced autophagy, in either immature or mature DCs. Hypoxia inhibited mTOR phosphorylation and activated a pro-autophagic program. By using different pharmacological inhibitors, we demonstrated that hypoxia-induced autophagy was mediated by PI3Ks, especially by Vps34. Furthermore, Vps34 expression was enhanced by LPS, a TLR4 ligand, along with the promotion of autophagy under hypoxia. The Vps34 inhibitor, SAR405, abolished hypoxia-induced autophagy, inhibited pro-survival signaling and viability, and increased the expression of proinflammatory cytokines. Our results underlined the impact of autophagy in the maintenance of DC homeostasis at both cell survival and inflammatory response levels, therefore, contributing to a better understanding of the significance of autophagy in DC physiology and pathology.
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Kayabasi, Cagla, Cigir Biray Avci, Sunde Yilmaz Susluer, Tugce Balci, Yusuf Baran, Guray Saydam, and Cumhur Gunduz. "Autophagic and Apoptotic Effects of Tyrosine Kinase Inhibitors in Myeloid Leukemia: Comparison of Three Generation." Blood 120, no. 21 (November 16, 2012): 4915. http://dx.doi.org/10.1182/blood.v120.21.4915.4915.
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Abstract Abstract 4915 The aim of the study was to evaluate the differences in cytotoxicity, apoptosis and autophagy levels in myeloid leukemia cell lines treated with tyrosine kinase inhibitors compared to cell line resistant to imatinib and control group. Chronic myeloid leukemia model was created by using cell lines as K-562 cell line for Ph+ chronic myeloid leukemia model, HL-60 cell line for acute promyelocytic Ph- leukemia model. NCI-BL2171 normal cell line was used as a control group while K562/ima3 cell line was used as an imatinib resistant model. Imatinib (STI571), Dasatinib (BMS-354825), Ponatinib (AP24534) were used as tyrosine kinase inhibitors in this study. Cytotoxicity analysis was conducted by WST-1 analysis. Apoptotis was evaluated by AnnexinV-enhanced green fluorescent protein (EGFP) and by Mitoprobe JC-1 for Mitochondrial Potential Detection. Autophagy was analyzed by The Premo Autophagy Tb/GFP TR-FRET LC3B assay which measures autophagy in cells expressing green fluorescent protein (GFP)-tagged LC3B using a Tb-based TR-FRET immunoassay approach. By using IC50 doses of tyrosine kinase inhibitors, autophagic effect of these drugs on cell lines were examined at 24th hours. Cells not treated with the active substance or chloroquine were considered as control groups. Chloroquine-treated cells were used as positive control for autophagy. LC3B-II increase is an indicator of autophagic suppression. Cells treated with chloroquine were compared with cells treated with active substances and concentrations of BacMam that displayed the highest LC3B-II increase were selected. Autophagic suppression ratio of the drugs was evaluated among the control group. Cytotoxicity, apoptosis and autophagy analysis results were provided in Table. Compared to control group, 30 μM chloroquine repressed autophagy 1. 93, 1. 48, 2. 74 and 1. 54 fold in K562, HL-60, K562/ima3 and NCI-BL 2171 cells, respectively. In HL-60 cells while Imatinib represented 0. 77 fold autophagy, it repressed autophagy 1. 77 and 3. 49 fold in K562 and K562/ima3 cells respectively. Dasatinib repressed autophagy 2. 11, 1. 95 and 4. 62 fold and Ponatinib repressed autophagy 2. 09, 1. 60 and 9. 15 fold in K562, HL-60, K562/ima3 cells respectively. Imatinib, Dasatinib and Ponatinib did not repressed autophagy in NCI-BL 2171 cells. In conclusion, apoptosis and autophagy paradox was illuminated in myeloid leukemia cells via tyrosine kinase inhibitors and autophagy may be a new strategy for targeted therapy in myeloid leukemia after clarifying responsible genes and proteins in signal transduction pathways. Cytotoxicity Apoptosis Autophagy WST-1 IC50 (nM) Annexin V JC-1 Premo Autophagy Ýmatinib Dasatinib Ponatinib Ýmatinib Dasatinib Ponatinib Ýmatinib Dasatinib Ponatinib Ýmatinib Dasatinib Ponatinib K562 24th hour 1.70 3.65 3.05 3.07 1.37 1.35 1.43 1.77 2.11 2.09 48th hour 650.00 0.24 2.67 2.51 2.32 2.03 2.35 2.06 72nd hour 4.53 4.81 3.00 2.97 3.07 2.50 HL-60 24th hour 1.33 1.26 1.32 1.29 1.22 1.34 0.77 1.95 1.60 48th hour 18000.00 1.39 1.23 1.41 1.61 1.92 1.96 72nd hour 896.00 607.00 2.21 1.80 2.82 1.58 1.73 2.23 K562/ima3 24th hour 1.33 0.76 1.69 1.51 1.36 1.59 3.49 4.62 9.15 48th hour 18350.00 1830.00 9.87 1.80 1.94 2.03 2.82 1.22 1.40 72nd hour 1.34 1.44 1.41 2.61 1.40 1.56 NCI-BL 2171 24th hour 48.00 2.48 2.79 2.62 3.99 4.04 4.25 1.01 0.88 0.90 48th hour 274.00 30.00 4.11 4.33 4.15 5.05 2.75 3.11 72nd hour 6.14 6.04 6.03 8.27 3.71 3.95 Disclosures: No relevant conflicts of interest to declare.
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Yeh, Trai-Ming, and Chiao-Hsuan Chao. "Macrophage migration inhibitory factor-induced autophagy is involved in thrombin-mediated endothelial cell hyperpermeability." Journal of Immunology 196, no. 1_Supplement (May 1, 2016): 51.2. http://dx.doi.org/10.4049/jimmunol.196.supp.51.2.
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Abstract Sepsis is a disease in which systemic inflammation-induced vascular leakage and disseminated intravascular coagulation lead to multiple organ failure. Despite a high mortality andmorbidity, there is currently no specific drug for sepsis. Thrombin, a serineprotease that mediates key sepsis-related pathologies, both activates coagulation cascades and acts as a mediator to induce vascular hyperpermeability and inflammation. It is known that thrombin can induce endothelial cells to secrete macrophage migration inhibitor factor (MIF) and MIFcan cause endothelial hyperpermeability via autophagy. However, it is unclearwhether MIF-induced autophagy is involved in thrombin-mediated vascular hyperpermeability. Herein, we show that thrombin treatment induced hyperpermeability, which was accompanied by VE-cadherin translocation in the human microvascular endothelial cell line (HMEC-1). Additionally, thrombin could induce MIF secretion and autophagy in HMEC-1 cells. Inhibition of MIF by its antibody or inhibitors could reduce thrombin-induced endothelial hyperpermeability and autophagy. However, inhibition of autophagy prevented only endothelial hyperpermeability, not MIF secretion. Finally, both MIF and autophagy inhibitors reduced thrombin- induced vascular leakage in vitro. Together, our data suggest that MIF-induced autophagy is involved in thrombin-mediated endothelial cell hyperpermeability. Further studies designed to test whether autophagy inhibitors could prevent endothelial barrier dysfunction in sepsis may provide potential therapeutic modalities to reduce sepsis-related mortality.
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Li, Yuejin, Peng Zhang, Jian Zhang, Weimin Bao, Jinyuan Li, Yan Wei, Jinchao Ni, and Kunmei Gong. "Role of Autophagy Inducers and Inhibitors in Intestinal Barrier Injury Induced by Intestinal Ischemia–Reperfusion (I/R)." Journal of Immunology Research 2022 (July 30, 2022): 1–10. http://dx.doi.org/10.1155/2022/9822157.
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Objectives. Intestinal epithelial barrier function is an important mechanical barrier to maintain intestinal homeostasis and resist the invasion of intestinal pathogens and microorganisms. However, intestinal epithelial barrier function is vulnerable to damage under intestinal ischemia–reperfusion (I/R) injury. Under a category of pathophysiological conditions, including I/R, autophagy plays a crucial role. This study is aimed at discussing the role of autophagy inhibitors and activators in intestinal epithelial barrier function after intestinal I/R by changing autophagy levels. Methods. Mice with intestinal IR underwent 45 minutes of surgery for superior mesenteric artery occlusion. The autophagy inhibitor 3-MA and the autophagy inducer rapamycin (RAP) were used to change the level of autophagy, and then, the expressions of tight junction proteins and intestinal barrier function were detected. Results. The results showed that the autophagy inhibitor 3-MA aggravated intestinal epithelial barrier dysfunction, while the autophagy inducer RAP attenuated intestinal epithelial barrier dysfunction. In addition, promoting autophagy may promote occludin expression by inhibiting claudin-2 expression. Conclusion. Upregulation of autophagy levels by autophagy inducers can enhance intestinal epithelial barrier function after intestinal I/R.
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Shu, Chih-Wen, Charitha Madiraju, Dayong Zhai, Kate Welsh, Paul Diaz, Eduard Sergienko, Renata Sano, and John C. Reed. "High-Throughput Fluorescence Assay for Small-Molecule Inhibitors of Autophagins/Atg4." Journal of Biomolecular Screening 16, no. 2 (January 18, 2011): 174–82. http://dx.doi.org/10.1177/1087057110392996.
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Autophagy is an evolutionarily conserved process for catabolizing damaged proteins and organelles in a lysosome-dependent manner. Dysregulation of autophagy may cause various diseases, such as cancer and neurodegeneration. However, the relevance of autophagy to diseases remains controversial because of the limited availability of chemical modulators. Herein, the authors developed a fluorescence-based assay for measuring activity of the autophagy protease, autophagin-1(Atg4B). The assay employs a novel reporter substrate of Atg4B composed of a natural substrate (LC3B) fused to an assayable enzyme (PLA2) that becomes active upon cleavage by this cysteine protease. A high-throughput screening (HTS) assay was validated with excellent Z′ factor (>0.7), remaining robust for more than 5 h and suitable for screening of large chemical libraries. The HTS assay was validated by performing pilot screens with 2 small collections of compounds enriched in bioactive molecules ( n = 1280 for Lopac™ and 2000 for Spectrum™ library), yielding confirmed hit rates of 0.23% and 0.70%, respectively. As counterscreens, PLA2 and caspase-3 assays were employed to eliminate nonspecific inhibitors. In conclusion, the LC3B-PLA2 reporter assay provides a platform for compound library screening for identification and characterization of Atg4B-specific inhibitors that may be useful as tools for interrogating the role of autophagy in disease models.
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Chu, Su, Yao-Te Hsieh, Marcus JGW Ladds, Sonia Lane, and Ravi Bhatia. "Enhanced Targeting of FLT3-ITD+AML Stem Cells through Combined Inhibition of SIRT1 and Autophagic Flux." Blood 128, no. 22 (December 2, 2016): 31. http://dx.doi.org/10.1182/blood.v128.22.31.31.
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Abstract Internal tandem duplication mutations of the Fms-like tyrosine kinase 3 (FLT3-ITD) are amongst the most common mutations in acute myeloid leukemia (AML) patients, and are associated with poor clinical outcome. Tyrosine kinase inhibitors (TKI) targeting FLT3 are only partially effective and fail to yield full and lasting responses in FLT3-ITD+ AML patients. Therefore, additional strategies to enhance eradication of FLT3-ITD+ AML cells are required to improve outcomes. We have previously shown that the NAD-dependent SIRT1 deacetylase is selectively overexpressed in human FLT3-ITD AML leukemia stem cells (LSC), which demonstrate increased sensitivity to the small molecule SIRT1 inhibitor Tenovin-6 (Li at al., Cell Stem Cell 15, 431, 2014). We have now determined that Tenovin-6, in addition to SIRT-1 inhibition and activation of p53 activity, also functions as an effective inhibitor of autophagic flux, mediated by an aliphatic tertiary amine side chain that mediates alkalization of lysosomes. Comparison of Tenovin (TV) analogs with or without SIRT1 or autophagy inhibitory properties revealed that TVs can kill melanoma cells independently of SIRT1 inhibition and that autophagy blockade correlates with ability to completely eliminate cancer cells. Autophagy is known to promote survival and facilitate tumorigenesis and drug resistance by degradation and recycling of intracellular proteins and organelles in lysosomes. In the present work, we investigated the roles of SIRT1 inhibition and autophagy inhibition in targeting AML cells. The TV analogs studied includedTV-39 (inhibits both SIRT1 and autophagy), TV-39OH (inhibits SIRT1 alone), TV-50 (inhibits autophagy alone), and TV-50OH (inhibits neither). We observed that FLT3-ITD + AML cell lines (MV4-11 and MOLM13) demonstrated increased sensitivity to TV analogs with either autophagy inhibitory (TV-50) or SIRT1 inhibitory (TV39OH) effects compared with FLT3-WT cell lines (OCI-AML3 and KG1A). The combination of TV50 and TV39OH resulted in synergistic cytotoxicity in FLT3-ITD+ AML cell lines, as well as in primary AML CD34+cells bearing the FLT3-ITD mutation (Table 1). Western blot analysis indicated that FLT3-ITD+ cells treated with TV39 showed accumulation of LC3B-II, consistent with blockade of a late stage of autophagy, as well as increased acetylated and total p53 expression, consistent with SIRT1 inhibition. Cells treated with TV39OH showed increased acetylated and total p53 without change of LC3B-II levels, whereas cells treated with TV50 alone showed only increase of LC3B-II and not in p53 levels. Knockdown (KD) of p53 using lentivirus-expressed shRNA constructs reversed the inhibitory effects of TVs with both SIRT1 and autophagy inhibitory properties. The combination of the FLT3 TKI AC220 with either TV39OH or TV50 resulted in synergistic cytotoxicity in MV4;11 and Molm-13 cells, indicating that these agents could induce enhance elimination of FLT3-ITD+ cells by TKIs. To confirm the interaction of SIRT1 and autophagy inhibition in targeting FLT3-ITD AML cells, we knocked down ATG5 and SIRT1 expression in MV4-11 and Molm13 cells using lentivirus expressed shRNA. KD of either ATG5 or SIRT1 individually resulted in significant induction of apoptosis and inhibition of proliferation in AML FLT3-ITD cell lines compared with shRNA controls (Table 2). The combined knockdown of SIRT1 and ATG5 induced further increase in apoptosis compared to KD of individual genes. KD of SIRT1 or ATG5 significantly enhanced levels of ROS in FLT3-ITD positive cell lines, measured using the CellROX® Deep Red Reagent (shCtrl vs. shATG5+shSirt1, 1 vs1.74 p=0.02; shCtrl vs shATG5, 1vs 1.83, p=0.009; shCtrl vs. shATG5, 1 vs. 1.85 p=0.008). In an ongoing experiment, we are checking the effect of KD of SIRT1, ATG5 or of both SIRT1 and ATG5 in Molm13 cells in their growth in NSG mice. We conclude that combined inhibition of SIRT1 activity and autophagic flow synergistically targets FLT3-ITD+ AML cell lines and primary CD34+ cells, and enhances their targeting by FLT3 kinase inhibitors. Combined targeting of autophagic flow and SIRT1 activity appears to be a promising strategy to enhance elimination of FLT3-ITD+ AML stem cells. Disclosures No relevant conflicts of interest to declare.
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Li, Xincong, Hanxiao Liu, Yijun Yu, Lan Ma, Chao Liu, and Leiying Miao. "Graphene Oxide Quantum Dots-Induced Mineralization via the Reactive Oxygen Species-Dependent Autophagy Pathway in Dental Pulp Stem Cells." Journal of Biomedical Nanotechnology 16, no. 6 (June 1, 2020): 965–74. http://dx.doi.org/10.1166/jbn.2020.2934.
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As an important recycling and degradation system, autophagy is considered to be critical in regulating stem cell differentiation. It has been shown that graphene oxide quantum dots (GOQDs) are a robust biological labelling tool for stem cells with little cytotoxicity. In this study, we explored the role of autophagy in regulating the impact of GOQDs on the odontoblastic differentiation of DPSCs during autophagy. Western blotting and immunofluorescence staining were used to evaluate the autophagic activity of DPSCs. Quantitative PCR, alizarin red S staining, and alkaline phosphatase staining were used to examine DPSC odontoblastic differentiation. The impacts of ROS scavengers on autophagy induction and reactive oxygen species (ROS) levels were also measured. Lentiviral vectors carrying Beclin1 siRNA sequences, as well as autophagy inhibitors (3-MA and bafilomycin A1), were used to inhibit autophagy. Initial exposure to GOQDs increased autophagic activity and enhanced DPSC mineralization. Autophagy inhibition suppressed GOQD-induced odontoblastic differentiation. Moreover, GOQD treatment induced autophagy in a ROS-dependent manner. GOQDs promoted differentiation, which could be modulated via ROS-induced autophagy.
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Lee, Hee-Ju, Eun-Jin Park, Byeol Ryu, Hyo-Moon Cho, Duc-Trong Nghiem, Ha-Thanh-Tung Pham, Cheol-Ho Pan, and Won-Keun Oh. "Benzylisoquinoline Alkaloids from the Stems of Limacia scandens and Their Potential as Autophagy Inhibitors." Pharmaceuticals 15, no. 11 (October 28, 2022): 1332. http://dx.doi.org/10.3390/ph15111332.
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Limacia scandens is traditionally used to treat depression and affective disorders in Malaysia. The chemical compositions have been reported to include bisbenzylisoquinoline and aporphine-type alkaloids in the genus Limacia Lour., but studies on the components of L. scandens have rarely been reported. Therefore, this study was conducted to determine new benzylisoquinoline alkaloid derivatives with autophagy regulation activity from this plant. Bioactivity-guided isolation was applied to various column chromatography methods using RP-18, Sephadex LH-20 open column chromatography, and preparative HPLC. The chemical structures of the isolated compounds were elucidated through spectroscopic data analysis, including NMR, HR-ESI-MS, and ECD data. In addition, isolated compounds were tested for autophagy-regulating activity in HEK293 cells expressing GFP-L3. Three new dimeric benzylisoquinoline alkaloids (1−3), one new 4-hydroxybenzoic acid-conjugated benzylisoquinoline alkaloid (4), and six known compounds (5−10) were isolated from the stems of L. scandens. All compounds (1–10) were screened for autophagy regulation in HEK293 cells stably expressing the GFP-LC3 plasmid. Among the isolated compounds, 1, 2, and 4 showed autophagic regulation activity that blocked the process of combining autophagosomes and lysosomes. They also inhibit the protein degradation process from the autolysosome as inhibitors of autophagy. Novel benzylisoquinoline alkaloids from L. scandens showed potent potency for the inhibition of autophagic flux. This study provides potential candidates for developing natural autophagy inhibitors for disease prevention and treatment.
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Savvidou, Ioanna, Tiffany T. Khong, Stephen K. Horrigan, and Andrew Spencer. "Overcoming Innate Resistance to a Beta-Catenin Inhibitor-BC2059- By Manipulating Autophagy in Multiple Myeloma." Blood 128, no. 22 (December 2, 2016): 5669. http://dx.doi.org/10.1182/blood.v128.22.5669.5669.
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Abstract Introduction: Chemoresistance is a major challenge in the development of new therapies in multiple myeloma [MM]. Inhibition of autophagy has been shown to restore chemosensitivity in several tumors. We have previously validated a beta-catenin inhibitor (BC2059) which targets the Wnt/beta-catenin signaling pathway. Aim: In the present study we aim to overcome innate resistance to BC2059 by manipulating the autophagic pathway. Methods: Autophagic flux was estimated by measurement of LC3II/LC3I in the absence and presence of hydroxychloroquine [HQ] by Western blot [WB]. Induction of autophagy was measured by the increase of LC3II/LC3I by WB, and concomitant drop of p62 expression by Flow Cytometry [FC]. Combination Indices [CI] were calculated using Calcusyn software. Results: BC2059 induces apoptosis in a dose-dependent manner by induction of both the intrinsic and extrinsic apoptotic pathways, (increase of active -caspase-8, -caspase-9 and -caspase-3 measured by FC and cleaved PARP by WB) in all human myeloma cell lines [HMCL] tested. All HMCL tested have significant autophagic flux at baseline. Chemical inhibition of autophagy has an anti-proliferative effect, decreasing the relative cell numbers from 40% (NCI-H929) to 23% (KMS12BM) at 24hr. In parallel BC2059 is able to induce autophagy in a dose dependent manner. Induction of autophagy is BC2059 specific as treatment with melphalan or bortezomib at relative equal anti-proliferative doses did not increase LC3II/LC3I. Further autophagic inhibition by HQ was synergistic for all HMCL with CI of 0.7-0.3 (CI<1.1 indicates synergy). Interestingly, inhibition of autophagy halved the LD50 of BC2059 in a resistant HMCL (LP1). Other autophagy inhibitors (3-MA, bafilomycin A1 and NH4Cl) were also synergistic with BC2059 in LP1. Conclusion: BC2059 exerts cytotoxicity mainly by induction of apoptosis but also induces cyto-protective autophagy. Autophagy inhibition was able to overcome innate resistance to the drug, ameliorating its cytotoxic effect. This study warrants further investigation. Disclosures Horrigan: betacatpharmaceuticals: Employment.
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Chandler, C. S., and F. J. Ballard. "Regulation of the breakdown rates of biotin-containing proteins in Swiss 3T3-L1 cells." Biochemical Journal 251, no. 3 (May 1, 1988): 749–55. http://dx.doi.org/10.1042/bj2510749.
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1. Degradation rate constants for individual biotin-labelled proteins were measured in Swiss 3T3-L1 adipocytes that had been incubated with inhibitors of autophagy or of lysosomal proteolysis. 2. Inhibitory effects produced by 10 mM-3-methyladenine and a combination of 5 mM-NH4Cl and leupeptin (50 micrograms/ml) were approximately equal. The inclusion of NH4Cl did not significantly enhance the responses to 3-methyladenine, suggesting that autophagy was already maximally inhibited. 3. The extent of inhibition by 3-methyladenine or by the NH4Cl/leupeptin mixture was similar for the cytosolic enzyme acetyl-CoA carboxylase and for the three mitochondrial carboxylases. This inhibition averaged 50%. The breakdown rate of a more-stable 38 kDa biotin-containing mitochondrial protein was more responsive to the inhibitory agents. These results are best explained by mitochondrial proteolysis occurring via a combination of the degradation of whole mitochondria within autophagic vacuoles, supplemented by the selective intramitochondrial breakdown of more labile proteins. 4. A number of intermediate products in the degradation of biotin-containing proteins were detected. Differences in the patterns of radioactivity between these peptides after incubation of cells in the presence of inhibitors of the breakdown process provided evidence that some peptides were produced before autophagy, others as a result of intralysosomal inhibition, while at least one was associated with intramitochondrial proteolysis.
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Cho, Kyoung Sang, Jang Ho Lee, Jeiwon Cho, Guang-Ho Cha, and Gyun Jee Song. "Autophagy Modulators and Neuroinflammation." Current Medicinal Chemistry 27, no. 6 (March 16, 2020): 955–82. http://dx.doi.org/10.2174/0929867325666181031144605.
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Background: Neuroinflammation plays a critical role in the development and progression of various neurological disorders. Therefore, various studies have focused on the development of neuroinflammation inhibitors as potential therapeutic tools. Recently, the involvement of autophagy in the regulation of neuroinflammation has drawn substantial scientific interest, and a growing number of studies support the role of impaired autophagy in the pathogenesis of common neurodegenerative disorders. Objective: The purpose of this article is to review recent research on the role of autophagy in controlling neuroinflammation. We focus on studies employing both mammalian cells and animal models to evaluate the ability of different autophagic modulators to regulate neuroinflammation. Methods: We have mostly reviewed recent studies reporting anti-neuroinflammatory properties of autophagy. We also briefly discussed a few studies showing that autophagy modulators activate neuroinflammation in certain conditions. Results: Recent studies report neuroprotective as well as anti-neuroinflammatory effects of autophagic modulators. We discuss the possible underlying mechanisms of action of these drugs and their potential limitations as therapeutic agents against neurological disorders. Conclusion: Autophagy activators are promising compounds for the treatment of neurological disorders involving neuroinflammation.
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Bellodi, Cristian, Maria Rosa Lidonnici, Ashley Hamilton, Gudmundur V. Helgason, Angela R. Soliera, Mattia Ronchetti, Sara Galavotti, et al. "Targeting Autophagy Potentiates Imatinib-Induced Cell Death in Philadelphia Positive Cells Including Primary CML Stem Cells." Blood 112, no. 11 (November 16, 2008): 1070. http://dx.doi.org/10.1182/blood.v112.11.1070.1070.
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Abstract Imatinib mesylate (IM), a potent ATP-competitive inhibitor of the BCR/ABL tyrosine kinase, has become standard therapy for patients with chronic myelogenous leukemia (CML). However, the main limitations of IM- and second generation tyrosine kinase inhibitor (TKI)-based therapy are the insurgence of resistance in patients and the intrinsic refractoriness of primitive Philadelphia-positive stem cells. Therefore, there is the need to develop new therapeutic approaches that, in combination with TKI, might be more effective in targeting the stem cell population and preventing the outgrowth of TKI-resistant CML cells. TKI-induced elimination of BCR/ABL-dependent intracellular signals is known to trigger apoptosis, but it is unclear whether this also activates additional cell death and/or survival pathways. We show that IM treatment induces autophagy in CML blast crisis cell lines, CML primary cells and p210BCR/ABL-expressing 32Dcl3 (32D) myeloid precursor cells, but not in 32D cells expressing v-Src or the IM-resistant T315I p210BCR/ABL mutant. IM-induced autophagy does not involve c-Abl, as it is also observed in cells co-expressing p210BCR/ABL and the IM-resistant T315I c-Abl mutant. Induction of autophagy is associated with endoplasmic reticulum-stress and is suppressed by depletion of intracellular calcium. By contrast, ectopic Bcl-2 expression does not block IM-induced autophagy. Suppression of autophagy by pharmacological inhibitors or siRNA-mediated knockdown of essential autophagy genes enhances cell death induced by IM in cell lines and primary CML cells, demonstrating that induction of autophagy has a pro-survival effect. Critically, the combination of TKI with autophagy inhibitors results in near complete elimination of phenotypically (CD34+38−) and functionally (colony forming cells) defined CML stem cells. Together, these findings suggest that autophagy inhibitors may enhance the therapeutic effects of TKI in the treatment of CML.
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Jiang, Tian-Xia, Jiang-Bo Zou, Qian-Qian Zhu, Cui Hua Liu, Guang-Fei Wang, Ting-Ting Du, Zi-Yu Luo, et al. "SIP/CacyBP promotes autophagy by regulating levels of BRUCE/Apollon, which stimulates LC3-I degradation." Proceedings of the National Academy of Sciences 116, no. 27 (June 18, 2019): 13404–13. http://dx.doi.org/10.1073/pnas.1901039116.
Full textAbstract:
BRUCE/Apollon is a membrane-associated inhibitor of apoptosis protein that is essential for viability and has ubiquitin-conjugating activity. On initiation of apoptosis, the ubiquitin ligase Nrdp1/RNF41 promotes proteasomal degradation of BRUCE. Here we demonstrate that BRUCE together with the proteasome activator PA28γ causes proteasomal degradation of LC3-I and thus inhibits autophagy. LC3-I on the phagophore membrane is conjugated to phosphatidylethanolamine to form LC3-II, which is required for the formation of autophagosomes and selective recruitment of substrates. SIP/CacyBP is a ubiquitination-related protein that is highly expressed in neurons and various tumors. Under normal conditions, SIP inhibits the ubiquitination and degradation of BRUCE, probably by blocking the binding of Nrdp1 to BRUCE. On DNA damage by topoisomerase inhibitors, Nrdp1 causes monoubiquitination of SIP and thus promotes apoptosis. However, on starvation, SIP together with Rab8 enhances the translocation of BRUCE into the recycling endosome, formation of autophagosomes, and degradation of BRUCE by optineurin-mediated autophagy. Accordingly, deletion of SIP in cultured cells reduces the autophagic degradation of damaged mitochondria and cytosolic protein aggregates. Thus, by stimulating proteasomal degradation of LC3-I, BRUCE also inhibits autophagy. Conversely, SIP promotes autophagy by blocking BRUCE-dependent degradation of LC3-I and by enhancing autophagosome formation and autophagic destruction of BRUCE. These actions of BRUCE and SIP represent mechanisms that link the regulation of autophagy and apoptosis under different conditions.
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Karmacharya, Ujjwala, and Jong-Wha Jung. "Small Molecule Inhibitors for Unc-51-like Autophagy-Activating Kinase Targeting Autophagy in Cancer." International Journal of Molecular Sciences 24, no. 2 (January 4, 2023): 953. http://dx.doi.org/10.3390/ijms24020953.
Full textAbstract:
Autophagy is a cellular process that removes damaged components of cells and recycles them as biochemical building blocks. Autophagy can also be induced to protect cells in response to intra- and extracellular stresses, including damage to cellular components, nutrient deprivation, hypoxia, and pathogenic invasion. Dysregulation of autophagy has been attributed to various diseases. In particular, autophagy protects cancer cells by supporting tumor cell survival and the development of drug resistance. Understanding the pathophysiological mechanisms of autophagy in cancer has stimulated the research on discovery and development of specific inhibitors targeting various stages of autophagy. In recent years, Unc-51-like autophagy-activating kinase (ULK) inhibitors have become an attractive strategy to treat cancer. This review summarizes recent discoveries and developments in small-molecule ULK inhibitors and their potential as anticancer agents. We focused on structural features, interactions with binding sites, and biological effects of these inhibitors. Overall, this review will provide guidance for using ULK inhibitors as chemical probes for autophagy in various cancers and developing improved ULK inhibitors that would enhance therapeutic benefits in the clinic.
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Rahman, Md Ataur, Kazi Rejvee Ahmed, MD Hasanur Rahman, Md Anowar Khasru Parvez, In-Seon Lee, and Bonglee Kim. "Therapeutic Aspects and Molecular Targets of Autophagy to Control Pancreatic Cancer Management." Biomedicines 10, no. 6 (June 20, 2022): 1459. http://dx.doi.org/10.3390/biomedicines10061459.
Full textAbstract:
Pancreatic cancer (PC) begins within the organ of the pancreas, which produces digestive enzymes, and is one of the formidable cancers for which appropriate treatment strategies are urgently needed. Autophagy occurs in the many chambers of PC tissue, including cancer cells, cancer-related fibroblasts, and immune cells, and can be fine-tuned by various promotive and suppressive signals. Consequently, the impacts of autophagy on pancreatic carcinogenesis and progression depend greatly on its stage and conditions. Autophagy inhibits the progress of preneoplastic damage during the initial phase. However, autophagy encourages tumor formation during the development phase. Several studies have reported that both a tumor-promoting and a tumor-suppressing function of autophagy in cancer that is likely cell-type dependent. However, autophagy is dispensable for pancreatic ductal adenocarcinoma (PDAC) growth, and clinical trials with autophagy inhibitors, either alone or in combination with other therapies, have had limited success. Autophagy’s dual mode of action makes it therapeutically challenging despite autophagy inhibitors providing increased longevity in medical studies, highlighting the need for a more rigorous review of current findings and more precise targeting strategies. Indeed, the role of autophagy in PC is complicated, and numerous factors must be considered when transitioning from bench to bedside. In this review, we summarize the evidence for the tumorigenic and protective role of autophagy in PC tumorigenesis and describe recent advances in the understanding of how autophagy may be regulated and controlled in PDAC.