iProXProteomicsMo LiHomo Sapienshttp://www.iprox.org/page/project.html?id=IPX0009515000limo@hsc.pku.edu.cnPeking University Third HospitaliProX<h4>Background</h4>The high mortality rate associated with epithelial ovarian cancer (EOC) is primarily due to recurrence and chemoresistance, underscoring the urgent need for innovative therapeutic approaches that leverage newly identified vulnerabilities in cancer cells. While conventional chemotherapies induce apoptosis by targeting DNA or mitotic machinery, ferroptosis represents a new distinct form of programmed cell death characterised by the accumulation of lipid peroxides.<h4>Methods</h4>The sensitivity of different EOC cell lines to ferroptosis inducers was evaluated using cell viability assays and lipid peroxidation measurements. Live-cell imaging with the pH-sensitive CD63-pHuji reporter was performed to track the extracellular export of acyl-CoA synthetase long-chain family member 4 (ACSL4) via exosomes. The upstream regulator of ACSL4 were identified through immunoprecipitation-mass spectrometry (IP-MS) and validated using protein binding assays. Finally, cell-derived xenograft (CDX) and patient-derived xenograft (PDX) models were utilised to evaluate the therapeutic potential overcoming ferroptosis resistance.<h4>Findings</h4>In this study, we found that interferon (IFN)-γ combined with arachidonic acid (AA), which are endogenous ferroptosis inducers, could initiate ferroptosis in most EOC cells. However, some EOC cells displayed significant resistance. Contrary to the typical increase in ACSL4 protein observed in ferroptosis-sensitive cells, resistant EOC cells exhibited surprisingly low levels of this pro-ferroptotic lipid metabolic protein. Intriguingly, this reduction is attributed to the exosomal expulsion of ACSL4 protein, revealing a distinct cellular mechanism to evade ferroptosis. We further identified VIPAS39 as a pivotal regulator in sorting ACSL4 into late endosomes, thereby facilitating their subsequent release as exosomes. Notably, targeting VIPAS39 not only overcomes the resistance to ferroptotic cell death but also markedly suppresses tumour growth.<h4>Interpretation</h4>Our findings uncover the crucial role of VIPAS39 in ferroptosis evasion by facilitating the exporting of ACSL4 protein via exosomes, highlighting VIPAS39 as a promising target for ferroptosis-based anti-cancer therapy.<h4>Funding</h4>Funded by Beijing Municipal Natural Science Foundation (Key program Z220011), National Natural Science Foundation of China (NSFC) (T2225006, T2488301, 82272948), Peking University Medicine Youth Science and Technology Innovation 'Sail Plan' Project Type B Medical Interdisciplinary Seed Fund (71006Y3171), GuangDong Basic and Applied Basic Research Foundation (2021A1515110820), and the special fund of the National Clinical Key Speciality Construction Program, P. R. China (2023).VIPAS39 confers ferroptosis resistance in epithelial ovarian cancer through exporting ACSL4.Jiang Yuening Y, Li Jie J, Wang Tianzhen T, Gu Xiaoyang X, Li Xinyu X, Liu Zhaofei Z, Yue Wei W, Li Mo MfalseVIPAS39 confers ferroptosis resistance in ovarian cancer through exporting ACSL4Ovarian cancer (OC), particularly its epithelial subtype (EOC), is the most lethal gynecological malignancy worldwide, with the majority of patients diagnosed at an advanced stage and a five-year survival rate below 30%. The standard treatment, primarily consisting of cytoreductive surgery and platinum-based chemotherapy, often leads to recurrence and metastasis, highlighting the urgent need for innovative therapeutic approaches. Ferroptosis, a form of regulated cell death driven by iron-dependent lipid peroxidation, offers a promising avenue due to cancer cells’ heightened susceptibility compared to non-cancerous cells. This susceptibility is due to their increased iron requirements and the resultant vulnerability to peroxidation of polyunsaturated fatty acids in cell membranes. Notably, acyl-CoA synthase long-chain family member 4 (ACSL4) plays a pivotal role in this process by catalyzing the esterification of free fatty acids into membrane phospholipids, a critical step for ferroptosis induction. Our study explores the synergistic effects of interferon-gamma (IFN-γ) and arachidonic acid (AA), natural inducers of ferroptosis that increase ACSL4 expression and activity, thereby promoting cell death in EOC. We demonstrate that while some EOC cell lines are highly responsive to IFN-γ and AA, indicating effective ferroptosis induction, others show resistance, likely due to the secretion of ACSL4 via exosomes. This resistance is mediated by VIPAS39, a protein crucial for protein sorting in the endosomal pathway and exosome biogenesis. Inhibiting VIPAS39 may thus enhance the sensitivity of resistant ovarian cancer cells to ferroptosis-inducing treatments, presenting a novel therapeutic strategy to curb ovarian cancer progression. This study provides foundational insights into the heterogeneous response of EOC cells to ferroptosis and underscores the potential of targeting vesicular trafficking processes to overcome drug resistance.Fri Aug 30 00:00:00 GMT+01:00 2024PXD055446960640088627