Project description:Ferroptosis, an iron-dependent form of regulated cell death driven by lipid peroxidation, functions as an innate tumor suppression mechanism. However, the regulatory networks governing ferroptosis sensitivity in cancer cells remain incompletely elucidated. In this study, we identify RAB11FIP5 as a novel negative regulator of ferroptosis in head and neck squamous cell carcinoma (HNSCC) cells. Mechanistically, RAB11FIP5 competitively binds to RAB11A against RAB11FIP1, thereby inhibiting the recycling of transferrin (TF) and transferrin receptor (TFR), which are critical for cellular iron import. Furthermore, we demonstrate that USP52 acts as a deubiquitinase that stabilizes RAB11FIP5 by removing the K48 ubiquitin chains in ferroptosis-resistant HNSCC cells. In a subcutaneous xenograft model, knockout of RAB11FIP5 not only enhances the anti-tumor efficacy of the ferroptosis inducer IKE but also suppresses HNSCC tumor growth even in the absence of IKE treatment. Analysis of public databases and patient tissue samples reveals that high RAB11FIP5 expression in HNSCC tumors correlates with poor prognosis. Collectively, our findings elucidate a previously unrecognized mechanism by which RAB11FIP5 regulates ferroptosis through modulating TF/TFR recycling, highlighting its potential as both a prognostic marker and a therapeutic target for HNSCC.
Project description:To seek ferroptosis related genes in liver cancer cells, we treated HepG2 cells using ferroptosis inducer Erastin and inhibitor Ferrostatin, respectively. We found that a subset of genes were up-regulated in Erastin treatment groups and down-regulated in Ferrostatin treatment groups, suggesting that these genes might be correlated with ferroptosis.
Project description:Ferroptosis is a unique form of intracellular iron-dependent cell death that differs from apoptosis, necrosis, and autophagy. GPX4, an antioxidant defense enzyme, plays a pivotal role as regulator of ferroptosis. Extensive researches suggest that targeting GPX4 holds promise for cancer therapy. However, the current GPX4 inhibitors face challenges due to unfavorable drug-like properties, which hinder their progress in clinical development. In this study, we identified a novel inhibitor called MI-2, demonstrating potent ferroptosis-inducing capacity. Mechanistically, MI-2 effectively inhibits the activity of GPX4 by direct interaction. Furthermore, MI-2 promotes the degradation of GPX4 through its well-established target, MALT1. In multiple cancer models, MI-2 has demonstrated synergistic effects when combined with sorafenib or regorafenib, resulting in enhanced ferroptosis induction. These findings highlight the dual modulatory effects of MI-2 on GPX4 activity and stability, offering a promising starting point for the development of drug-like GPX4 inhibitors with translational potential.
Project description:Cancers coopt stress-response pathways to drive oncogenesis, dodge immune surveillance, and resist cytotoxic therapies. Several of these provide protection from ferroptosis, iron-mediated oxidative cell death. Here, we found dramatic sensitization to ferroptosis upon disruption of cap-dependent translation in diffuse large B-cell lymphoma (DLBCL). Specifically, rocaglate inhibitors of the eIF4A1 RNA helicase synergized with pharmacologic ferroptosis inducers, driven by a collapse of glutathione production that protects polyunsaturated fatty acids from ferroptotic oxidation. These effects occur despite initial up-regulation of specific protective factors. We find lost translation of NRF2, oncogenic master regulator of antioxidant gene-expression, is a key consequence of eIF4A1 inhibition. In vivo, combination of the clinical rocaglate zotatifin with a pharmacologically optimized ferroptosis inducer eradicated DLBCL patient derived xenografts. Moreover, we found zotatifin pre-exposure sensitized DLBCL to CD19-directed chimeric antigen receptor (CAR-19) T cells. Translational disruption therefore provides new opportunities to leverage therapeutic impacts of ferroptosis inducers including cytotoxic immunotherapies.
Project description:Despite the remarkable success of programmed death 1/PD-L1 inhibition in tumor therapy, only a minority of patients benefits from it. Previous studies suggest the anti-PD-1 treatment failure may attribute to the intrinsic functions of PD-L1 in cancer cells. Here, we established a genome-wide CRISPR synthetic lethality screen to systematic explore the PD-L1 intrinsic function in head and neck squamous cell carcinoma (HNSCC) cells. Ferroptosis related genes were identified to be essential for PD-L1 deficient cell viability. Genetic and pharmacological induction of ferroptosis accelerated cell death in PD-L1 knockout cells. PD-L1 knockout cells were also highly susceptible to immunogenic ferroptosis in vitro and in vivo. Mechanistically, nuclear PD-L1 transcriptionally activated SOD2 expression to maintain redox homeostasis. Importantly, the lower ROS and ferroptosis were observed in HNSCC patients with the higher expression of PD-L1. In summary, our study illustrates that PD-L1 confers ferroptosis resistance by activating SOD2-meidated redox homeostasis in HNSCC cells, indicating an enhanced therapeutic effect can be achieved by targeting the intrinsic PD-L1 function during immunotherapy.
Project description:Despite the remarkable success of programmed death 1/PD-L1 inhibition in tumor therapy, only a minority of patients benefits from it. Previous studies suggest the anti-PD-1 treatment failure may attribute to the intrinsic functions of PD-L1 in cancer cells. Here, we established a genome-wide CRISPR synthetic lethality screen to systematic explore the PD-L1 intrinsic function in head and neck squamous cell carcinoma (HNSCC) cells. Ferroptosis related genes were identified to be essential for PD-L1 deficient cell viability. Genetic and pharmacological induction of ferroptosis accelerated cell death in PD-L1 knockout cells. PD-L1 knockout cells were also highly susceptible to immunogenic ferroptosis in vitro and in vivo. Mechanistically, nuclear PD-L1 transcriptionally activated SOD2 expression to maintain redox homeostasis. Importantly, the lower ROS and ferroptosis were observed in HNSCC patients with the higher expression of PD-L1. In summary, our study illustrates that PD-L1 confers ferroptosis resistance by activating SOD2-meidated redox homeostasis in HNSCC cells, indicating an enhanced therapeutic effect can be achieved by targeting the intrinsic PD-L1 function during immunotherapy.
Project description:Ferroptosis, a non-apoptotic programmed cell death triggered by excessive iron-dependent lipid peroxidation, plays a pivotal role in tumor progression. Significant progress has been made in elucidating the role of transcription factors in the regulation of ferroptosis. Nevertheless, the identification of the key transcription factor responsible for inducing ferroptosis remains elusive. In this study, we discovered that ATOH8 is upregulated in prostate cancer cells treated with the ferroptosis inducer. Overexpression of ATOH8 increased the vulnerability of prostate cancer to ferroptosis, while ATOH8 deletion promotes ferroptosis evasion. Mechanistically, ATOH8 suppresses the transcription of SCD, reducing the synthesis of monounsaturated fatty acids that confer resistance to ferroptosis. Additionally, ATOH8 works in conjunction with the E protein E47 to form a transcriptional repression complex that inhibits SCD transcription. Furthermore, we discovered that EZH2 epigenetically suppresses the expression of ATOH8 through DNA methylation and H3K27 methylation. Interestingly, EZH2 was found to be downregulated in ferroptosis, resulting in an upregulation of ATOH8. Pharmacological inhibition of EZH2 combined with ferroptosis inducer significantly suppresses prostate cancer growth in vitro and in vivo. Together, our findings unveil that EZH2-mediated ATOH8 downregulation promotes ferroptosis evasion and suggest that pharmacological manipulation of EZH2 and ATOH8 is a promising therapeutic strategy for prostate cancer.
Project description:Ferroptosis, a non-apoptotic programmed cell death triggered by excessive iron-dependent lipid peroxidation, plays a pivotal role in tumor progression. Significant progress has been made in elucidating the role of transcription factors in the regulation of ferroptosis. Nevertheless, the identification of the key transcription factor responsible for inducing ferroptosis remains elusive. In this study, we discovered that ATOH8 is upregulated in prostate cancer cells treated with the ferroptosis inducer. Overexpression of ATOH8 increased the vulnerability of prostate cancer to ferroptosis, while ATOH8 deletion promotes ferroptosis evasion. Mechanistically, ATOH8 suppresses the transcription of SCD, reducing the synthesis of monounsaturated fatty acids that confer resistance to ferroptosis. Additionally, ATOH8 works in conjunction with the E protein E47 to form a transcriptional repression complex that inhibits SCD transcription. Furthermore, we discovered that EZH2 epigenetically suppresses the expression of ATOH8 through DNA methylation and H3K27 methylation. Interestingly, EZH2 was found to be downregulated in ferroptosis, resulting in an upregulation of ATOH8. Pharmacological inhibition of EZH2 combined with ferroptosis inducer significantly suppresses prostate cancer growth in vitro and in vivo. Together, our findings unveil that EZH2-mediated ATOH8 downregulation promotes ferroptosis evasion and suggest that pharmacological manipulation of EZH2 and ATOH8 is a promising therapeutic strategy for prostate cancer.