Sestrin2-Mediated Autophagy Contributes to Drug Resistance via Endoplasmic Reticulum Stress in Human Osteosarcoma.
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ABSTRACT:
SUBMITTER: Tang Z
PROVIDER: S-EPMC8502982 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Neuroblastoma is the leading cause of cancer death in children aged 1 to 4 years. Particularly, five-year overall survival for high-risk neuroblastoma is below 50% with no curative options when refractory or relapsed. Most of current therapies target cell division and proliferation, thereby inducing DNA damage and programmed cell death. However, aggressive tumours often present alterations of these processes and are resistant to therapy. Therefore, exploring alternative pathways to induce tumour cell death will provide new therapeutic opportunities for these patients. In this study we aimed at testing the therapeutic potential of ABTL0812, a novel anticancer drug that induces cytotoxic autophagy to eliminate cancer cells, which is currently in phase II clinical trials of adult tumours. Here, we show that ABTL0812 impaired the viability of clinical representative neuroblastoma cell lines regardless of genetic alterations associated to bad prognosis and resistance to therapy. Oral administration of ABTL0812 to mice bearing neuroblastoma xenografts impaired tumour growth. Furthermore, our findings revealed that, in neuroblastoma, ABTL0812 induced cancer cell death via induction of endoplasmic reticulum stress, activation of the unfolded protein response, autophagy and apoptosis. Remarkably, ABTL0812 potentiated the antitumour activity of chemotherapies and differentiating agents such as irinotecan and 13-cis-retinoic acid. In conclusion, ABTL0812 distinctive mechanism of action makes it standout to be used alone or in combination in high-risk neuroblastoma patients.
| S-EPMC7498451 | biostudies-literature
Project description:Chronic exposure to bile acid in the liver due to impaired bile flow induces cholestatic liver disease, resulting in hepatotoxicity and liver fibrosis. Sestrin2, a highly conserved, stress-inducible protein, has been implicated in cellular responses to multiple stress conditions and the maintenance of cellular homeostasis. However, its role in cholestatic liver injury is not fully understood. In this study, we investigated the role of hepatic Sestrin2 in cholestatic liver injury and its underlying mechanisms using in vivo and in vitro approaches. Hepatic Sestrin2 expression was upregulated by activating transcription factor 4 (ATF4) and CCAAT/enhancer-binding protein-β (C/EBP-β) after treatment with bile acids and correlated with endoplasmic reticulum (ER) stress responses. Bile-duct ligation (BDL)-induced hepatocellular apoptosis and liver fibrosis were exacerbated in Sestrin2-knockout (Sesn2-/-) mice. Moreover, Sestrin2 deficiency enhanced cholestasis-induced hepatic ER stress, whereas Sestrin2 overexpression ameliorated bile acid-induced ER stress. Notably, the mammalian target of rapamycin (mTOR) inhibitor rapamycin and the AMP-activated protein kinase (AMPK) activator AICAR reversed bile acid-induced ER stress in Sestrin2-deficient cells. Furthermore, Sestrin2 deficiency promoted cholestasis-induced hepatic pyroptosis by activating NLRP3 inflammasomes. Thus, our study provides evidence for the biological significance of Sestrin2 and its relationship with cholestatic liver injury, suggesting the potential role of Sestrin2 in regulating ER stress and inflammasome activation during cholestatic liver injury.
| S-EPMC8980001 | biostudies-literature
Project description:BackgroundOsteosarcoma is the most common primary bone tumor in children and adolescents. Unfortunately, osteosarcoma treatments often fail due to the development of chemoresistance, of which the underlying molecular mechanisms still remain unclear. In this study, we demonstrated that HSP90AA1 gene is responsible for drug resistance in osteosarcoma through an autophagy-related mechanism.MethodsshRNAs were transfected into osteosarcoma cells for knockdown of HSP90AA1 gene. Stable HSP90AA1 overexpressing osteosarcoma cell lines were obtained by lentivirus infection. mRNA and protein expressions of HSP90AA1 in osteosarcoma cells were tested by quantitative real-time PCR and western blot, respectively. Autophagy of osteosarcoma cells was detected by western blot of LC3, transmission electron microscopy and fluorescence microscope. mRFP-GFP-LC3 lentiviral transfection was also performed to detect autophagic flux. NOD/SCID mices were inoculated with MG-63 tumor cells transfected with HSP90AA1 specific shRNA. TUNEL and LC3 staining were performed to detect apoptosis and autophagy of resected tumor tissues.ResultsDoxorubicin, cisplatin, and methotrexate, which are commonly used in chemotherapy, each induced HSP90AA1 upregulation in human osteosarcoma cells. Suppression of HSP90AA1 restored the sensitivity of osteosarcoma cells to chemotherapy both in vivo and in vitro. Mechanism study indicated that autophagy is responsible for the chemoresistance in osteosarcoma cells. HSP90AA1 increased drug resistance by inducing autophagy and inhibiting apoptosis. Suppression of HSP90AA1 diminished autophagic protection in response to chemotherapy in osteosarcoma cells. Moreover, HSP90AA1 promotes autophagy through PI3K/Akt/mTOR pathway and inhibits apoptosis through JNK/P38 pathway.ConclusionWe showed that chemotherapy agents can induce HSP90AA1 expression in osteosarcoma cells. And HSP90AA1, acting as an important regulator of autophagy, is a critical factor in the development of osteosarcoma chemoresistance both in vitro and in vivo. HSP90AA1 provides a novel therapeutic target for improving osteosarcoma treatment.
| S-EPMC6114771 | biostudies-literature
Project description:There is a growing evidence of the role of autophagy in pancreatic ? cell homeostasis. During development of type 2 diabetes, ? cells are required to supply the increased demand of insulin. In such a stage, ? cells have to address high ER stress conditions that could lead to abnormal insulin secretion, and ultimately, ? cell death and overt diabetes. In this study, we used insulin secretion-deficient ? cells derived from fetal mice. These cells present an increased accumulation of polyubiquitinated protein aggregates and LC3B-positive puncta, when compared with insulinoma-derived ? cell lines. We found that insulin secretion deficiency renders these cells hypersensitive to endoplasmic reticulum (ER) stress-mediated cell death. Chemical or shRNA-mediated inhibition of autophagy increased ? cell death under ER stress. On the other hand, rapamycin treatment increased both autophagy and cell survival under ER stress. Insulin secretion-deficient ? cells showed a marked reduction of the antiapoptotic protein BCL2, together with increased BAX expression and ERN1 hyperactivation upon ER stress induction. These results showed how insulin secretion deficiency in ? cells may be contributing to ER stress-mediated cell death, and in this regard, we showed how the autophagic response plays a prosurvival role.
| S-EPMC3541286 | biostudies-literature
Project description:Constitutive cell-autonomous immunity in metazoans predates interferon-inducible immunity and comprises primordial innate defense. Phagocytes mobilize interferon-inducible responses upon engagement of well-characterized signaling pathways by pathogen-associated molecular patterns (PAMPs). The signals controlling deployment of constitutive cell-autonomous responses during infection have remained elusive. Vita-PAMPs denote microbial viability, signaling the danger of cellular exploitation by intracellular pathogens. We show that cyclic-di-adenosine monophosphate in live Gram-positive bacteria is a vita-PAMP, engaging the innate sensor stimulator of interferon genes (STING) to mediate endoplasmic reticulum (ER) stress. Subsequent inactivation of the mechanistic target of rapamycin mobilizes autophagy, which sequesters stressed ER membranes, resolves ER stress, and curtails phagocyte death. This vita-PAMP-induced ER-phagy additionally orchestrates an interferon response by localizing ER-resident STING to autophagosomes. Our findings identify stress-mediated ER-phagy as a cell-autonomous response mobilized by STING-dependent sensing of a specific vita-PAMP and elucidate how innate receptors engage multilayered homeostatic mechanisms to promote immunity and survival after infection.
| S-EPMC5811766 | biostudies-literature
Project description:Sestrin2 is a highly conserved stress-inducible protein, acting as a crucial part in regulating homeostasis in response to various stress conditions in the cell. However, the role of Sestrin2 in regulating cell apoptosis related to endoplasmic reticulum (ER) has not been fully investigated. Our study presented here aims to reveal the effect of Sestrin2 in tunicamycin (TM)-induced cell apoptosis related to ER stress and its underlying molecular mechanisms. The results demonstrated that Sestrin2 expression was significantly upregulated correlated with ER stress responses in TM treated HepG2 cells. Sestrin2 overexpression obviously alleviated ER stress with the determination of ER stress-related proteins expression. In addition, Sestrin2 overexpression inhibited cell apoptosis with the examination of apoptosis-related proteins and TUNEL assay. However, Sestrin2 knockdown further promoted the ER stress-mediated cell apoptosis. The further mechanistic study revealed that Sestrin2 overexpression inhibited TM-induced mTOR pathway activation. Taken together, our current study indicated that Sestrin2 overexpression ameliorates ER stress-induced apoptosis via inhibiting mTOR pathway in HepG2 cells.
| S-EPMC9759384 | biostudies-literature
Project description:Accumulation of misfolded proinsulin in the ?-cell leads to dysfunction induced by endoplasmic reticulum (ER) stress, with diabetes as a consequence. Autophagy helps cellular adaptation to stress via clearance of misfolded proteins and damaged organelles. We studied the effects of proinsulin misfolding on autophagy and the impact of stimulating autophagy on diabetes progression in Akita mice, which carry a mutation in proinsulin, leading to its severe misfolding. Treatment of female diabetic Akita mice with rapamycin improved diabetes, increased pancreatic insulin content, and prevented ?-cell apoptosis. In vitro, autophagic flux was increased in Akita ?-cells. Treatment with rapamycin further stimulated autophagy, evidenced by increased autophagosome formation and enhancement of autophagosome-lysosome fusion. This was associated with attenuation of cellular stress and apoptosis. The mammalian target of rapamycin (mTOR) kinase inhibitor Torin1 mimicked the rapamycin effects on autophagy and stress, indicating that the beneficial effects of rapamycin are indeed mediated via inhibition of mTOR. Finally, inhibition of autophagy exacerbated stress and abolished the anti-ER stress effects of rapamycin. In conclusion, rapamycin reduces ER stress induced by accumulation of misfolded proinsulin, thereby improving diabetes and preventing ?-cell apoptosis. The beneficial effects of rapamycin in this context strictly depend on autophagy; therefore, stimulating autophagy may become a therapeutic approach for diabetes.
| S-EPMC3609555 | biostudies-literature
Project description:BackgroundEndoplasmic reticulum (ER) stress and its consequent unfolded protein response (UPR) are believed to be associated with progression, survival and chemoresistance of a variety of tumor cells through multiple cellular processes, including autophagy. Therefore, the ER stress-autophagy pathway presents a potential molecular target for therapeutic intervention. The objective of this study was to evaluate the therapeutic efficacy of ER stress and autophagy modulators in the context of pancreatic ductal adenocarcinoma (PDAC).MethodsWe first targeted IRE1?, an important regulator of the UPR, through STF-083010 treatment in PDAC cell lines in vitro. Chloroquine was then used to target autophagy and an optimal combination treatment was developed using chloroquine, sunitinib and gemcitabine. Apoptosis was analyzed using TUNEL assay, autophagy was estimated using lysotracker staining and electron microscopy, and UPR was analyzed using anti-GRP78 immunostaining and XBP1 splicing. Transplantation of PDAC derived KPCP1 and Panc02 cells in mouse pancreas were performed to study treatment efficacy in vivo.ResultsSuppression of the IRE1? by STF-083010 alone resulted in increased lysosomes and reduced viability of PDAC cells. Chloroquine treatment alone inhibited downstream autophagy but was insufficient in reducing PDAC cell growth. However, combining STF-083010 and chloroquine had additive anti-tumor efficacy when used with gemcitabine. Sunitinib alone caused abnormal maturation of the autolysosomes with increased intracellular multivesicular bodies and increased apoptosis evident in PDAC cells. Sunitinib showed a synergistic effect with chloroquine in reducing in vitro PDAC cell viability and significantly increased the efficacy of gemcitabine in human and murine PDAC cell lines. The anti-proliferative effect of gemcitabine was significantly increased when used in combination with sunitinib and/or chloroquine in both in vitro and in vivo PDAC models. The addition of sunitinib and/or chloroquine to gemcitabine, resulted in a significantly increased survival of the animals without noticeably increased toxicity. Sunitinib, gemcitabine and chloroquine treated mice showed a significant reduction of GRP78 expression, reduced cell proliferation and increased apoptosis in pancreas, compatible with a tumor response.ConclusionsSunitinib combined with chloroquine reduces tumor growth through suppression of autophagy and increased apoptosis. Co-administration of modulators of ER stress-mediated autophagy with chemotherapy presents a novel therapeutic approach in PDAC.
| S-EPMC6038181 | biostudies-literature
Project description:Pancreatic ductal adenocarcinoma (PDAC) shows a high level of basal autophagy. Here we investigated the role of optineurin (OPTN) in PDAC cell lines, which is a prominent member of the autophagy system. To that purpose, mining of publically available databases showed that OPTN is highly expressed in PDAC and that high levels of expression are related to reduced survival. Therefore, the role of OPTN on proliferation, migration, and colony formation was investigated by transient knockdown in Miapaca, BXPC3, and Suit2-007 human PDAC cells. Furthermore, gene expression modulation in response to OPTN knockdown was assessed by microarray. The influence on cell cycle distribution and cell death signaling cascades was followed by FACS, assays for apoptosis, RT-PCR, and western blot. Finally, autophagy and ROS induction were screened by acridine orange and DCFH-DA fluorescent staining respectively. OPTN knockdown caused significant inhibition of colony formation, increased migration and no significant effect on proliferation in Miapaca, BXPC3 and Suit2-007 cells. The microarray showed modulation of 293 genes in Miapaca versus 302 in Suit2-007 cells, of which 52 genes overlapped. Activated common pathways included the ER stress response and chaperone-mediated autophagy, which was confirmed at mRNA and protein levels. Apoptosis was activated as shown by increased levels of cleaved PARP, Annexin V binding and nuclear fragmentation. OPTN knockdown caused no increased vacuole formation as assessed by acridine orange. Also, there was only marginally increased ROS production. Combination of OPTN knockdown with the autophagy inducer erufosine or LY294002, an inhibitor of autophagy, showed additive effects, which led us to hypothesize that they address different pathways. In conclusion, OPTN knockdown was related to activation of ER stress response and chaperone-mediated autophagy, which tend to confine the damage caused by OPTN knockdown and thus question its value for PDAC therapy.
| S-EPMC6689035 | biostudies-literature
Project description:Colorectal cancer (CRC) is the third leading malignant tumor in the world, which has high morbidity and mortality. In this study we found that trichodermic acid (TDA), a secondary metabolite isolated from the plant endophytic fungus Penicillium ochrochloronthe with a variety of biological and pharmacological activities, exhibited the antitumor effects on colorectal cancer cells in vitro and in vivo. Our results showed that TDA inhibited the proliferation of colon cancer cells in a dose-dependent manner. TDA induces sustained endoplasmic reticulum stress, which triggers apoptosis through IRE1α/XBP1 and PERK/ATF4/CHOP pathways. In addition, we found that TDA mediated endoplasmic reticulum stress also induces autophagy as a protective mechanism. Moreover, combined treatment of TDA with autophagy inhibitors significantly enhanced its anticancer effect. In conclusion, our results indicated that TDA can induce ER stress and autophagy mediated apoptosis, suggesting that targeting ER stress and autophagy may be an effective strategy for the treatment of CRC.
| S-EPMC8197497 | biostudies-literature