SOCS2-enhanced ubiquitination of SLC7A11 promotes ferroptosis and radiosensitization in hepatocellular carcinoma

Ferroptosis in liver cancer: a key role of post-translational modifications

Ferroptosis is an emerging form of regulated cell death in an oxidative stress- and iron-dependent manner, primarily induced by the over-production of reactive oxygen species (ROS). Manipulation of ferroptosis has been considered a promising therapeutic approach to inhibit liver tumor growth. Nevertheless, the development of resistance to ferroptosis in liver cancer poses a significant challenge in cancer treatment. Post-translational modifications (PTMs) are crucial enzymatic catalytic reactions that covalently regulate protein conformation, stability and cellular activities. Additionally, PTMs play pivotal roles in various biological processes and divergent programmed cell death, including ferroptosis. Importantly, key PTMs regulators involved in ferroptosis have been identified as potential targets for cancer therapy. PTMs function of two proteins, SLC7A11, GPX4 involved in ferroptosis resistance have been extensively investigated in recent years. This review will summarize the roles of PTMs in ferroptosis-related proteins in hepatocellular carcinoma (HCC) treatment.

Danggui Buxue Tang improves therapeutic efficacy of doxorubicin in triple negative breast cancer via ferroptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Danggui Buxue Tang (DBT) has been used for over 800 years to enhance Qi and nourish Blood, and it is particularly beneficial for cancer patients. Recent research has shown that combining DBT with chemotherapy agents leads to superior anti-cancer effects, thereby enhancing therapeutic efficacy.

AIM OF THE STUDY

The aim of this study was to evaluate the effectiveness of a combination therapy involving doxorubicin (DOX) and Danggui Buxue Tang (DBT) in the treatment of triple-negative breast cancer (TNBC) and to elucidate the underlying mechanisms of action.

MATERIALS AND METHODS

In vitro experiments were performed using MDA-MB-231 and 4T1 cells, while in vivo experiments were carried out using MDA-MB-231 xenograft mice. The therapeutic effects of the combination therapy were evaluated using various techniques, including MTT assay, colony formation assay, flow cytometry, transwell assay, immunofluorescence, transmission electron microscopy (TEM), histological analysis, western blotting, and bioluminescence assay.

RESULTS

DBT was found to enhance DOX's anti-TNBC activity in vitro by promoting ferroptosis, as evidenced by the observed mitochondrial morphological changes using TEM. The combination therapy was also found to reduce the expression of Nrf2, HO-1, and GPX4, which are all targets for ferroptosis induction, while simultaneously increasing ROS production. Additionally, the combination therapy reduced nuclear accumulation and constitutive activation of Nrf2, which is a significant cause of chemotherapy resistance and promotes cancer growth. In vivo experiments using an MDA-MB-231 xenograft animal model revealed that the combination therapy significantly reduced tumor cell proliferation and accelerated TNBC deaths by modulating the Nrf2/HO-1/GPX4 axis, with no evidence of tissue abnormalities. Moreover, the combination therapy exhibited a liver protective effect, and administration of Fer-1 was able to reduce the ROS formation produced by the DBT + DOX combination therapy.

CONCLUSION

This study provides evidence that the combination therapy of DOX and DBT has the potential to treat TNBC by promoting ferroptosis through the Nrf2/HO-1/GPX4 axis.

SPTBN2 suppresses ferroptosis in NSCLC cells by facilitating SLC7A11 membrane trafficking and localization

The function of SLC7A11 in the process of ferroptosis is well-established, as it regulates the synthesis of glutathione (GSH), thereby influencing tumor development along with drug resistance in non-small cell lung cancer (NSCLC). However, the determinants governing SLC7A11's membrane trafficking and localization remain unknown. Our study identified SPTBN2 as a ferroptosis suppressor, enhancing NSCLC cells resistance to ferroptosis inducers. Mechanistically, SPTBN2, through its CH domain, interacted with SLC7A11 and connected it with the motor protein Arp1, thus facilitating the membrane localization of SLC7A11 - a prerequisite for its role as System Xc-, which mediates cystine uptake and GSH synthesis. Consequently, SPTBN2 suppressed ferroptosis through preserving the functional activity of System Xc- on the membrane. Moreover, Inhibiting SPTBN2 increased the sensitivity of NSCLC cells to cisplatin through ferroptosis induction, both in vitro and in vivo. Using Abrine as a potential SPTBN2 inhibitor, its efficacy in promoting ferroptosis and sensitizing NSCLC cells to cisplatin was validated. Collectively, SPTBN2 is a potential therapeutic target for addressing ferroptosis dysfunction and cisplatin resistance in NSCLC.

TIGAR reduces neuronal ferroptosis by inhibiting succinate dehydrogenase activity in cerebral ischemia

Ischemia Stroke (IS) is an acute neurological condition with high morbidity, disability, and mortality due to a severe reduction in local cerebral blood flow to the brain and blockage of oxygen and glucose supply. Oxidative stress induced by IS predisposes neurons to ferroptosis. TP53-induced glycolysis and apoptosis regulator (TIGAR) inhibits the intracellular glycolytic pathway to increase pentose phosphate pathway (PPP) flux, promotes NADPH production and thus generates reduced glutathione (GSH) to scavenge reactive oxygen species (ROS), and thus shows strong antioxidant effects to ameliorate cerebral ischemia/reperfusion injury. However, in the current study, prolonged ischemia impaired the PPP, and TIGAR was unable to produce NADPH but was still able to reduce neuronal ferroptosis and attenuate ischemic brain injury. Ferroptosis is a form of cell death caused by free radical-driven lipid peroxidation, and the vast majority of ROS leading to oxidative stress are generated by mitochondrial succinate dehydrogenase (SDH) driving reverse electron transfer (RET) via the mitochondrial electron transport chain. Overexpression of TIGAR significantly inhibited hypoxia-induced enhancement of SDH activity, and TIGAR deficiency further enhanced SDH activity. We also found that the inhibitory effect of TIGAR on SDH activity was related to its mitochondrial translocation under hypoxic conditions. TIGAR may inhibit SDH activity by mediating post-translational modifications (acetylation and succinylation) of SDH A through interaction with SDH A. SDH activity inhibition reduces neuronal ferroptosis by decreasing ROS production, eliminating MitoROS levels and attenuating lipid peroxide accumulation. Notably, TIGAR-mediated inhibition of SDH activity and ferroptosis was not dependent on the PPP-NADPH-GPX4 pathways. In conclusion, mitochondrial translocation of TIGAR in prolonged ischemia is an important pathway to reduce neuronal ferroptosis and provide sustainable antioxidant defense for the brain under prolonged ischemia, further complementing the mechanism of TIGAR resistance to oxidative stress induced by IS.

APE1 inhibition enhances ferroptotic cell death and contributes to hepatocellular carcinoma therapy

Ferroptosis, a regulated form of cell death triggered by iron-dependent lipid peroxidation, has emerged as a promising therapeutic strategy for cancer treatment, particularly in hepatocellular carcinoma (HCC). However, the mechanisms underlying the regulation of ferroptosis in HCC remain to be unclear. In this study, we have identified a novel regulatory pathway of ferroptosis involving the inhibition of Apurinic/apyrimidinic endonuclease 1 (APE1), a key enzyme with dual functions in DNA repair and redox regulation. Our findings demonstrate that inhibition of APE1 leads to the accumulation of lipid peroxidation and enhances ferroptosis in HCC. At the molecular level, the inhibition of APE1 enhances ferroptosis which relies on the redox activity of APE1 through the regulation of the NRF2/SLC7A11/GPX4 axis. We have identified that both genetic and chemical inhibition of APE1 increases AKT oxidation, resulting in an impairment of AKT phosphorylation and activation, which leads to the dephosphorylation and activation of GSK3β, facilitating the subsequent ubiquitin-proteasome-dependent degradation of NRF2. Consequently, the downregulation of NRF2 suppresses SLC7A11 and GPX4 expression, triggering ferroptosis in HCC cells and providing a potential therapeutic approach for ferroptosis-based therapy in HCC. Overall, our study uncovers a novel role and mechanism of APE1 in the regulation of ferroptosis and highlights the potential of targeting APE1 as a promising therapeutic strategy for HCC and other cancers.

Emerging role of ferroptosis in metabolic dysfunction-associated steatotic liver disease: revisiting hepatic lipid peroxidation

Metabolic dysfunction-associated steatohepatitis (MASH) is characterised by cell death of parenchymal liver cells which interact with their microenvironment to drive disease activity and liver fibrosis. The identification of the major death type could pave the way towards pharmacotherapy for MASH. To date, increasing evidence suggest a type of regulated cell death, named ferroptosis, which occurs through iron-catalysed peroxidation of polyunsaturated fatty acids (PUFA) in membrane phospholipids. Lipid peroxidation enjoys renewed interest in the light of ferroptosis, as druggable target in MASH. This review recapitulates the molecular mechanisms of ferroptosis in liver physiology, evidence for ferroptosis in human MASH and critically appraises the results of ferroptosis targeting in preclinical MASH models. Rewiring of redox, iron and PUFA metabolism in MASH creates a proferroptotic environment involved in MASH-related hepatocellular carcinoma (HCC) development. Ferroptosis induction might be a promising novel approach to eradicate HCC, while its inhibition might ameliorate MASH disease progression.

RNA processing modification mediated subtypes illustrate the distinctive features of tumor microenvironment in hepatocellular carcinoma

Multiple transcript isoforms of genes can be formed by processing and modifying the 5' and 3' ends of RNA. Herein, the aim of this study is to uncover the characteristics of RNA processing modification (RPM) in hepatocellular carcinoma (HCC), and to identify novel biomarkers and potential targets for treatment. Firstly, integrated bioinformatics analysis was carried out to identify risk prognostic RPM regulators (RPMRs). Then, we used these RPMRs to identify subtypes of HCC and explore differences in immune microenvironment and cellular function improvement pathways between the sub-types. Finally, we used the principal component analysis algorithms to estimate RPMscore, which were applied to 5 cohorts. Lower RPMscore among patients correlated with a declined survival rate, increased immune infiltration, and raised expression of immune checkpoints, aligning with the "immunity tidal model theory". The RPMscore exhibited robust, which was validated in multiple datasets. Mechanistically, low RPMscore can create an immunosuppressive microenvironment in HCC by manipulating tumor-associated macrophages. Preclinically, patients with high RPMscore might benefit from immunotherapy. The RPMscore is helpful in clustering HCC patients with distinct prognosis and immunotherapy. Our RPMscore model can help clinicians to select personalized therapy for HCC patients, and RPMscore may act a part in the development of HCC.

FERREG: ferroptosis-based regulation of disease occurrence, progression and therapeutic response

Ferroptosis is a non-apoptotic, iron-dependent regulatory form of cell death characterized by the accumulation of intracellular reactive oxygen species. In recent years, a large and growing body of literature has investigated ferroptosis. Since ferroptosis is associated with various physiological activities and regulated by a variety of cellular metabolism and mitochondrial activity, ferroptosis has been closely related to the occurrence and development of many diseases, including cancer, aging, neurodegenerative diseases, ischemia-reperfusion injury and other pathological cell death. The regulation of ferroptosis mainly focuses on three pathways: system Xc-/GPX4 axis, lipid peroxidation and iron metabolism. The genes involved in these processes were divided into driver, suppressor and marker. Importantly, small molecules or drugs that mediate the expression of these genes are often good treatments in the clinic. Herein, a newly developed database, named 'FERREG', is documented to (i) providing the data of ferroptosis-related regulation of diseases occurrence, progression and drug response; (ii) explicitly describing the molecular mechanisms underlying each regulation; and (iii) fully referencing the collected data by cross-linking them to available databases. Collectively, FERREG contains 51 targets, 718 regulators, 445 ferroptosis-related drugs and 158 ferroptosis-related disease responses. FERREG can be accessed at https://idrblab.org/ferreg/.

Mechanisms of ferroptosis in nonalcoholic fatty liver disease and therapeutic effects of traditional Chinese medicine: a review

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive accumulation of fat in hepatocytes (nonalcoholic fatty liver (NAFL)), and lobular inflammation and hepatocyte damage (which characterize nonalcoholic steatohepatitis (NASH) are found in most patients). A subset of patients will gradually develop liver fibrosis, cirrhosis, and eventually hepatocellular carcinoma, which is a deadly disease that threatens human life worldwide. Ferroptosis, a novel nonapoptotic form of programmed cell death (PCD) characterized by iron-dependent accumulation of reactive oxygen radicals and lipid peroxides, is closely related to NAFLD. Traditional Chinese medicine (TCM) has unique advantages in the prevention and treatment of NAFLD due to its multicomponent, multipathway and multitarget characteristics. In this review, we discuss the effect of TCM on NAFLD by regulating ferroptosis, in order to provide reference for the further development and application of therapeutic drugs to treat NAFLD.

Identification and validation of ferroptosis-related gene SLC2A1 as a novel prognostic biomarker in AKI

BACKGROUND

Emerging evidence reveals the key role of ferroptosis in the pathophysiological process of acute kidney injury (AKI). Our study aimed to investigate the potential ferroptosis-related gene in AKI through bioinformatics and experimental validation.

METHODS

The AKI single-cell sequencing dataset was retrieved from the GEO database and ferroptosis-related genes were extracted from the GENECARD website. The potential differentially expressed ferroptosis-related genes of AKI were selected. Functional enrichment analysis was performed. Machine learning algorithms were used to identify key ferroptosis-related genes associated with AKI. A multi-factor Cox regression analysis was used to construct a risk score model. The accuracy of the risk score model was validated using receiver operating characteristic (ROC) curve analysis. We extensively explored the immune landscape of AKI using CIBERSORT tool. Finally, expressions of ferroptosis DEGs were validated in vivo and in vitro by Western blot, ICH and transfection experiments.

RESULTS

Three hub genes (BAP1, MDM4, SLC2A1) were identified and validated by constructing drug regulatory network and subsequent screening using experimentally determined interactions. The risk mode showed the low-risk group had significantly better prognosis compared to high-risk group. The risk score was independently associated with overall survival. The ROC curve analysis showed that the prognosis model had good predictive ability. Additionally, CIBERSORT immune infiltration analysis suggest that the hub gene may influence cell recruitment and infiltration in AKI. Validation experiments revealed that SLC2A1 functions by regulating ferroptosis.

CONCLUSIONS

In summary, our study not only identifies SLC2A1 as diagnostic biomarker for AKI, but also sheds light on the role of it in AKI progression, providing novel insights for the clinical diagnosis and treatment of AKI.

Integrating single-cell and bulk sequencing data to identify glycosylation-based genes in non-alcoholic fatty liver disease-associated hepatocellular carcinoma

Background

The incidence of non-alcoholic fatty liver disease (NAFLD) associated hepatocellular carcinoma (HCC) has been increasing. However, the role of glycosylation, an important modification that alters cellular differentiation and immune regulation, in the progression of NAFLD to HCC is rare.

Methods

We used the NAFLD-HCC single-cell dataset to identify variation in the expression of glycosylation patterns between different cells and used the HCC bulk dataset to establish a link between these variations and the prognosis of HCC patients. Then, machine learning algorithms were used to identify those glycosylation-related signatures with prognostic significance and to construct a model for predicting the prognosis of HCC patients. Moreover, it was validated in high-fat diet-induced mice and clinical cohorts.

Results

The NAFLD-HCC Glycogene Risk Model (NHGRM) signature included the following genes: SPP1, SOCS2, SAPCD2, S100A9, RAMP3, and CSAD. The higher NHGRM scores were associated with a poorer prognosis, stronger immune-related features, immune cell infiltration and immunity scores. Animal experiments, external and clinical cohorts confirmed the expression of these genes.

Conclusion

The genetic signature we identified may serve as a potential indicator of survival in patients with NAFLD-HCC and provide new perspectives for elucidating the role of glycosylation-related signatures in this pathologic process.

Ferroptosis in cancer: From molecular mechanisms to therapeutic strategies

Ferroptosis is a non-apoptotic form of regulated cell death characterized by the lethal accumulation of iron-dependent membrane-localized lipid peroxides. It acts as an innate tumor suppressor mechanism and participates in the biological processes of tumors. Intriguingly, mesenchymal and dedifferentiated cancer cells, which are usually resistant to apoptosis and traditional therapies, are exquisitely vulnerable to ferroptosis, further underscoring its potential as a treatment approach for cancers, especially for refractory cancers. However, the impact of ferroptosis on cancer extends beyond its direct cytotoxic effect on tumor cells. Ferroptosis induction not only inhibits cancer but also promotes cancer development due to its potential negative impact on anticancer immunity. Thus, a comprehensive understanding of the role of ferroptosis in cancer is crucial for the successful translation of ferroptosis therapy from the laboratory to clinical applications. In this review, we provide an overview of the recent advancements in understanding ferroptosis in cancer, covering molecular mechanisms, biological functions, regulatory pathways, and interactions with the tumor microenvironment. We also summarize the potential applications of ferroptosis induction in immunotherapy, radiotherapy, and systemic therapy, as well as ferroptosis inhibition for cancer treatment in various conditions. We finally discuss ferroptosis markers, the current challenges and future directions of ferroptosis in the treatment of cancer.

Ferroptosis in hepatocellular carcinoma, from mechanism to effect

Hepatocellular carcinoma (HCC) is a prevalent malignant tumor worldwide, characterized by high malignancy and rapid progression. Most cases are diagnosed at intermediate to advanced stages. Current treatment methods have limited efficacy, resulting in high recurrence rates and poor prognosis. Radical hepatectomy remains the primary treatment for HCC, complemented by radiotherapy, chemotherapy, targeted therapy, and immunotherapy. Despite significant improvement in patient prognosis with radical hepatectomy, the five-year survival rate post-surgery remains low; thus necessitating exploration of more effective therapeutic approaches. Ferroptosis is a recently discovered form of cell death that can modulate the occurrence and development of HCC through various mechanisms. This article aims to elucidate the mechanism of ferroptosis and its impact on HCC development to provide novel insights for diagnosis and treatment.

SNHG1, interacting with SND1, contributes to sorafenib resistance of liver cancer cells by increasing m6A-mediated SLC7A11 expression and promoting aerobic glycolysis

Aerobic glycolysis plays an important role in multidrug resistance of cancer cells. Here, we screened different expressed lncRNAs associated with sorafenib resistance of liver cancer cells, by intersecting the bioinformatics analyses of TCGA and GEO (the GSE62813 dataset) databases. Our results revealed that the 18 upregulated lncRNAs in the intersection are associated with and enriched in metabolism of small molecule organic acids, suggesting their potential in glycolysis. The lncRNA small nucleolar RNA host gene 1 (Snhg1) was chosen as a potential regulator of aerobic glycolysis in liver cancer cells, for its significant promotion on lactate production. Gain- and loss-of-function experiments mediated by Crispr-Cas9 technique in HepG2 cells indicated that Snhg1 promoted cell proliferation, invasion, sorafenib resistance, and aerobic glycolysis. In the mechanism exploration, we found that Snhg1 can interact with SND1 protein, a famous RNA binding protein and recently identified "Reader" of N6-methyladenosine (m6A). SND1 was demonstrated to be positively regulated by Snhg1 and had similar promoting effects on proliferation, invasion, sorafenib resistance, and aerobic glycolysis of HepG2 cells. SND1 bound with and promoted the expression of SLC7A11, an aerobic glycolysis regulator. Furthermore, either silencing SLC7A11 or blocking aerobic glycolysis with 2-deoxy-d-glucose (2-DG) was able to reverse the promotion of Snhg1 overexpression on malignancy, sorafenib resistance, and aerobic glycolysis of HepG2 cells. Finally, in a liver cancer xenograft mouse model, we found that formed tumors with Snhg1-knocked-down HepG2 cells were more sensitive to sorafenib administration. Altogether, SNHG1 contributes to sorafenib resistance of liver cancer cells by promoting SND1-m6A-SLC7A11-mediated aerobic glycolysis.

GSTM3 enhances radiosensitivity of nasopharyngeal carcinoma by promoting radiation-induced ferroptosis through USP14/FASN axis and GPX4

BACKGROUND

Radiotherapy is a critical treatment modality for nasopharyngeal carcinoma (NPC). However, the mechanisms underlying radiation resistance and tumour recurrence in NPC remain incompletely understood.

METHODS

Oxidised lipids were assessed through targeted metabolomics. Ferroptosis levels were evaluated using cell viability, clonogenic survival, lipid peroxidation, and transmission electron microscopy. We investigated the biological functions of glutathione S-transferase mu 3 (GSTM3) in cell lines and xenograft tumours. Co-immunoprecipitation, mass spectrometry, and immunofluorescence were conducted to explore the molecular mechanisms involving GSTM3. Immunohistochemistry was performed to investigate the clinical characteristics of GSTM3.

RESULTS

Ionising radiation (IR) promoted lipid peroxidation and induced ferroptosis in NPC cells. GSTM3 was upregulated following IR exposure and correlated with IR-induced ferroptosis, enhancing NPC radiosensitivity in vitro and in vivo. Mechanistically, GSTM3 stabilised ubiquitin-specific peptidase 14 (USP14), thereby inhibiting the ubiquitination and subsequent degradation of fatty acid synthase (FASN). Additionally, GSTM3 interacted with glutathione peroxidase 4 (GPX4) and suppressed GPX4 expression. Combining IR treatment with ferroptosis inducers synergistically improved NPC radiosensitivity and suppressed tumour growth. Notably, a decrease in GSTM3 abundance predicted tumour relapse and poor prognosis.

CONCLUSIONS

Our findings elucidate the pivotal role of GSTM3 in IR-induced ferroptosis, offering strategies for the treatment of radiation-resistant or recurrent NPC.

Ferroptosis: Potential opportunities for natural products in cancer therapy

Cancer cells often exhibit defects in the execution of cell death, resulting in poor clinical outcomes for patients with many cancer types. Ferroptosis is a newly discovered form of programmed cell death characterized by intracellular iron overload and lipid peroxidation in the cell membrane. Increasing evidence suggests that ferroptosis is closely associated with a wide variety of physiological and pathological processes, particularly in cancer. Notably, various bioactive natural products have been shown to induce the initiation and execution of ferroptosis in cancer cells, thereby exerting anticancer effects. In this review, we summarize the core regulatory mechanisms of ferroptosis and the multifaceted roles of ferroptosis in cancer. Importantly, we focus on natural products that regulate ferroptosis in cancer cells, such as terpenoids, polyphenols, alkaloids, steroids, quinones, and polysaccharides. The clinical efficacy, adverse effects, and drug-drug interactions of these natural products need to be evaluated in further high-quality studies to accelerate their application in cancer treatment.

The ubiquitin codes in cellular stress responses

Ubiquitination/ubiquitylation, one of the most fundamental post-translational modifications, regulates almost every critical cellular process in eukaryotes. Emerging evidence has shown that essential components of numerous biological processes undergo ubiquitination in mammalian cells upon exposure to diverse stresses, from exogenous factors to cellular reactions, causing a dazzling variety of functional consequences. Various forms of ubiquitin signals generated by ubiquitylation events in specific milieus, known as ubiquitin codes, constitute an intrinsic part of myriad cellular stress responses. These ubiquitination events, leading to proteolytic turnover of the substrates or just switch in functionality, initiate, regulate, or supervise multiple cellular stress-associated responses, supporting adaptation, homeostasis recovery, and survival of the stressed cells. In this review, we attempted to summarize the crucial roles of ubiquitination in response to different environmental and intracellular stresses, while discussing how stresses modulate the ubiquitin system. This review also updates the most recent advances in understanding ubiquitination machinery as well as different stress responses and discusses some important questions that may warrant future investigation.

Ferroptosis-Based Therapeutic Strategies toward Precision Medicine for Cancer

Ferroptosis is a type of iron-dependent programmed cell death characterized by the dysregulation of iron metabolism and the accumulation of lipid peroxides. This nonapoptotic mode of cell death is implicated in various physiological and pathological processes. Recent findings have underscored its potential as an innovative strategy for cancer treatment, particularly against recalcitrant malignancies that are resistant to conventional therapies. This article focuses on ferroptosis-based therapeutic strategies for precision cancer treatment, covering the molecular mechanisms of ferroptosis, four major types of ferroptosis inducers and their inhibitory effects on diverse carcinomas, the detection of ferroptosis by fluorescent probes, and their implementation in image-guided therapy. These state-of-the-art tactics have manifested enhanced selectivity and efficacy against malignant carcinomas. Given that the administration of ferroptosis in cancer therapy is still at a burgeoning stage, some major challenges and future perspectives are discussed for the clinical translation of ferroptosis into precision cancer treatment.

Lipid Metabolism as a Potential Target of Liver Cancer

Hepatocellular carcinoma (HCC) stands as a severe malignant tumor with a profound impact on overall health, often accompanied by an unfavorable prognosis. Despite some advancements in the diagnosis and treatment of this disease, improving the prognosis of HCC remains a formidable challenge. It is noteworthy that lipid metabolism plays a pivotal role in the onset, development, and progression of tumor cells. Existing research indicates the potential application of targeting lipid metabolism in the treatment of HCC. This review aims to thoroughly explore the alterations in lipid metabolism in HCC, offering a detailed account of the potential advantages associated with innovative therapeutic strategies targeting lipid metabolism. Targeting lipid metabolism holds promise for potentially enhancing the prognosis of HCC.

Comprehensive analysis of disulfidptosis-related genes: a prognosis model construction and tumor microenvironment characterization in clear cell renal cell carcinoma

BACKGROUND

Disulfidptosis, a form of cell death induced by abnormal intracellular accumulation of disulfides, is a newly recognized variety of cell death. Clear cell renal cell carcinoma (ccRCC) is a usual urological tumor that poses serious health risks. There are few studies of disulfidptosis-related genes (DRGs) in ccRCC so far.

METHODS

The expression, transcriptional variants, and prognostic role of DRGs were assessed. Based on DRGs, consensus unsupervised clustering analysis was performed to stratify ccRCC patients into various subtypes and constructed a DRG risk scoring model. Patients were stratified into high or low-risk groups by this model. We focused on assessing the discrepancy in prognosis, TME, chemotherapeutic susceptibility, and landscape of immune between the two risk groups. Finally, we validated the expression and explored the biological function of the risk scoring gene FLRT3 through in vitro experiments.

RESULTS

The different subtypes had significantly different gene expression, immune, and prognostic landscapes. In the two risk groups, the high-risk group had higher TME scores, more significant immune cell infiltration, and a higher probability of benefiting from immunotherapy, but had a worse prognosis. There were also remarkable differences in chemotherapeutic susceptibility between the two risk groups. In ccRCC cells, the expression of FLRT3 was shown to be lower and its overexpression caused a decrease in cell proliferation and metastatic capacity.

CONCLUSIONS

Starting from disulfidptosis, we established a new risk scoring model which can provide new ideas for doctors to forecast patient survival and determine clinical treatment plans.

Butyrate enhances erastin-induced ferroptosis of lung cancer cells via modulating the ATF3/SLC7A11 pathway

Ferroptosis is a novel form of programmed cell death triggered by iron-dependent lipid peroxidation and has been associated with various diseases, including cancer. Erastin, an inhibitor of system Xc-, which plays a critical role in regulating ferroptosis, has been identified as an inducer of ferroptosis in cancer cells. In this study, we investigated the impact of butyrate, a short-chain fatty acid produced by gut microbiota, on erastin-induced ferroptosis in lung cancer cells. Our results demonstrated that butyrate significantly enhanced erastin-induced ferroptosis in lung cancer cells, as evidenced by increased lipid peroxidation and reduced expression of glutathione peroxidase 4 (GPX4). Mechanistically, we found that butyrate modulated the pathway involving activating transcription factor 3 (ATF3) and solute carrier family 7 member 11 (SLC7A11), leading to enhanced erastin-induced ferroptosis. Furthermore, partial reversal of the effect of butyrate on ferroptosis was observed upon knockdown of ATF3 or SLC7A11. Collectively, our findings indicate that butyrate enhances erastin-induced ferroptosis in lung cancer cells by modulating the ATF3/SLC7A11 pathway, suggesting its potential as a therapeutic agent for cancer treatment.

Targeting ferroptosis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignant tumor with complex survival mechanism and drug resistance, resulting in cancer-related high mortality in the world. Ferroptosis represents a form of regulated cell death, typically distinguished by iron-dependent lipid peroxidation. Cancer cells often employ antioxidant defenses to evade the harmful effects of excess iron. Recent research has proposed that directing interventions towards ferroptosis could serve as an effective strategy in curbing the proliferation and invasion of HCC. Immunotherapy has made some preliminary progress in the remodeling of immune microenvironment, but it has not completely inhibited HCC growth, invasion and drug resistance. Furthermore, ferroptosis is widely observed in the formation of immune microenvironment of HCC and mediates the response of many targeted drugs and immunotherapy. Clarifying the role of ferroptosis in these complex processes is expected to provide a new prospect for HCC treatment. In this review, we outline the mechanisms by which HCC develops invasiveness and drug resistance by evading iron-dependent death, and paint a comprehensive landscape of ferroptosis in different cell types in the HCC immune microenvironment.

TKT-PARP1 axis induces radioresistance by promoting DNA double-strand break repair in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) stands as the fifth most prevalent malignant tumor on a global scale and presents as the second leading cause of cancer-related mortality. DNA damage-based radiotherapy (RT) plays a pivotal role in the treatment of HCC. Nevertheless, radioresistance remains a primary factor contributing to the failure of radiation therapy in HCC patients. In this study, we investigated the functional role of transketolase (TKT) in the repair of DNA double-strand breaks (DSBs) in HCC. Our research unveiled that TKT is involved in DSB repair, and its depletion significantly reduces both non-homologous end joining (NHEJ) and homologous recombination (HR)-mediated DSB repair. Mechanistically, TKT interacts with PARP1 in a DNA damage-dependent manner. Furthermore, TKT undergoes PARylation by PARP1, resulting in the inhibition of its enzymatic activity, and TKT can enhance the auto-PARylation of PARP1 in response to DSBs in HCC. The depletion of TKT effectively mitigates the radioresistance of HCC, both in vitro and in mouse xenograft models. Moreover, high TKT expression confers resistance of RT in clinical HCC patients, establishing TKT as a marker for assessing the response of HCC patients who received cancer RT. In summary, our findings reveal a novel mechanism by which TKT contributes to the radioresistance of HCC. Overall, we identify the TKT-PARP1 axis as a promising potential therapeutic target for improving RT outcomes in HCC.

Ferrostatin-1 inhibits ferroptosis of vascular smooth muscle cells and alleviates abdominal aortic aneurysm formation through activating the SLC7A11/GPX4 axis

Ferroptosis, a type of iron-catalyzed necrosis, is responsible for vascular smooth muscle cell (VSMC) death and serves as a potential therapeutic target for alleviating aortic aneurysm. Here, our study explored the underlying mechanism of ferroptosis affecting VSMC functions and the resultant formation of AAA using its inhibitor Ferrostatin-1 (Fer-1). Microarray-based gene expression profiling was employed to identify differentially expressed genes related to AAA and ferroptosis. An AAA model was established by angiotensin II (Ang II) induction in apolipoprotein E-knockout (ApoE-/- ) mice, followed by injection of Fer-1 and RSL-3 (ferroptosis inducer). Then, the role of Fer-1 and RSL-3 in the ferroptosis of VSMCs and AAA formation was analyzed in Ang II-induced mice. Primary mouse VSMCs were cultured in vitro and treated with Ang II, Fer-1, sh-SLC7A11, or sh-GPX4 to assess the effect of Fer-1 via the SLC7A11/GPX axis. Bioinformatics analysis revealed that GPX4 was involved in the fibrosis formation of AAA, and there was an interaction between SLC7A11 and GPX4. In vitro assays showed that Fer-1 alleviated Ang II-induced ferroptosis of VSMCs and retard the consequent AAA formation. The mechanism was associated with activation of the SLC7A11/GPX4 pathway. Silencing of SLC7A11 or GPX4 could inhibit the ameliorating effect of Fer-1 on the ferroptosis of VSMCs. In vivo animal studies further demonstrated that Fer-1 inhibited Ang II-induced ferroptosis and vessel wall structural abnormalities in AAA mouse through activation of the SLC7A11/GPX4 pathway. Fer-1 may prevent AAA formation through activation of the SLC7A11/GPX4 pathway.

POU6F1 promotes ferroptosis by increasing lncRNA-CASC2 transcription to regulate SOCS2/SLC7A11 signaling in gastric cancer

OBJECTIVE

This study investigated the effect and mechanism of POU6F1 and lncRNA-CASC2 on ferroptosis of gastric cancer (GC) cells.

METHODS

GC cells treated with erastin and RSL3 were detected for ferroptosis, reactive oxygen species (ROS) level, and cell viability. The expression levels of POU6F1, lncRNA-CASC2, SOCS2, and ferroptosis-related molecules (GPX4 and SLC7A11) were also measured. The regulations among POU6F1, lncRNA-CASC2, FMR1, SOCS2, and SLC7A11 were determined. Subcutaneous tumor models were established, in which the expressions of Ki-67, SOCS2, and GPX4 were detected by immunohistochemistry.

RESULTS

GC patients with decreased expressions of POU6F1 and lncRNA-CASC2 had lower survival rate. Overexpression of POU6F1 or lncRNA-CASC2 decreased cell proliferation and GSH levels in GC cells, in addition to increasing total iron, Fe2+, MDA, and ROS levels. POU6F1 directly binds to the lncRNA-CASC2 promoter to promote its transcription. LncRNA-CASC2 can target FMR1 and increase SOCS2 mRNA stability to promote SLC7A11 ubiquitination degradation and activate ferroptosis signaling. Knockdown of SOCS2 inhibited the ferroptosis sensitivity of GC cells and reversed the effects of POU6F1 and lncRNA-CASC2 overexpression on ferroptosis in GC cells.

CONCLUSION

Transcription factor POU6F1 binds directly to the lncRNA-CASC2 promoter to promote its expression, while upregulated lncRNA-CASC2 increases SOCS2 stability and expression by targeting FMR1, thereby inhibiting SLC7A11 signaling to promote ferroptosis in GC cells and inhibit GC progression.

Malignant cell receptor-ligand subtypes guide the prediction of prognosis and personalized immunotherapy of liver cancer

OBJECTIVE

Liver cancer is a prevalent disease with a dismal prognosis. The aim of the research is to identify subgroups based on malignant cell receptor ligand gene from single-cell RNA, which might lead to customized immunotherapy for patients with liver cancer.

METHODS

Based on scRNA-seq data, we identified the receptor-ligand genes associated with prognosis and classify patients into molecular subtypes by univariate Cox regression and consensus clustering. LASSO regression was performed to construct a prognostic model, which was validated in TCGA and ICGC datasets. Immune infiltration and prediction of immunotherapy response were analyzed using ssGSEA, ESTIMATE, TIDE, and TRS score calculation. Finally, qPCR and Western blot validation of key genes and protein levels in cell lines.

RESULTS

A risk model using 16-gene expression levels predicted liver cancer patients' prognosis. The RiskScore associated significantly with tumor clinical characteristics and immunity, integrated with clinicopathological features for survival prediction. Differential expression of SRXN1 was verified in hepatocellular carcinoma and normal liver cells.

CONCLUSION

Our study utilizes single-cell analysis to investigate the communication between malignant cells and other cell types, identifying molecular subtypes based on malignant cell receptor ligand genes, offering new insights for the development of personalized immunotherapy and prognostic prediction models.

Genomic and transcriptomic profiling of hepatocellular carcinoma reveals a rare molecular subtype

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide, occurring predominantly in patients with underlying chronic liver disease and cirrhosis. Here, we describe a case of a 62-year-old man that was admitted to our hospital and diagnosed with HCC where the cancer has already metastasized to the retroperitoneum and peritoneum. In order to better characterize the HCC, both the cancerous liver tissue and the adjacent normal liver tissue of the patient were collected and subjected to a genomic, transcriptomic and proteomic analysis. Our patient carries a highly mutated HCC, which is characterized by both somatic mutation in the following genes ALK, CDK6, TP53, PGR. In addition, we observe several molecular alterations that are associated with potential therapy resistance, for example the expression of the organic-anion-transporting polypeptide (OATP) family members B1 and B3, that mediate the transport of the anticancer drugs, has been found decreased. Overall, our molecular profiling potentially classify the patient with poor prognosis and possibly displaying resistance to pharmacological therapy.

Identification and validation of SLCO4C1 as a biological marker in hepatocellular carcinoma based on anoikis classification features

BACKGROUND

Hepatocellular carcinoma (HCC) exhibits a high degree of invasiveness and is closely associated with rapid disease progression. Multiple lines of evidence indicate a strong correlation between anoikis resistance and tumor progression, invasion, and metastasis. Nevertheless, the classification of anoikis in HCC and the investigation of novel biological target mechanisms in this context continue to pose challenges, requiring further exploration.

METHODS

Combined with HCC samples from TCGA, GEO and ICGC databases, cluster analysis was conducted on anoikis genes, revealing novel patterns among different subtypes. Significant gene analysis of different gene subtypes was performed using WCGNA. The anoikis prognostic risk model was established by Lasso-Cox. Go, KEGG, and GSEA were applied to investigate pathway enrichment primarily observed in risk groups. We compared the disparities in immune infiltration, TMB, tumor microenvironment (TME), and drug sensitivity between the two risk groups. RT-qPCR and Western blotting were performed to validate the expression levels of SLCO4C1 in HCC. The biological functions of SLCO4C1 in HCC cells were assessed through various experiments, including CCK8 assay, colony formation assay, invasion migration assay, wound healing assay, and flow cytometry analysis.

RESULTS

HCC was divided into 2 anoikis subtypes, and the subtypeB had a better prognosis. An anoikis prognostic model based on 12 (COPZ2, ACTG2, IFI27, SPP1, EPO, SLCO4C1, RAB26, STC2, RAC3, NQO1, MYCN, HSPA1B) risk genes is important for survival and prognosis. Significant differences were observed in immune cell infiltration, TME, and drug sensitivity analysis between the risk groups. SLCO4C1 was downregulated in HCC. SLCO4C1 downregulation promoted the proliferation, invasion, migration, and apoptosis of HCC cells. The tumor-suppressive role of SLCO4C1 in HCC has been confirmed.

CONCLUSIONS

Our study presents a novel anoikis classification method for HCC that reveals the association between anoikis features and HCC. The anoikis feature is a critical biomarker bridging tumor cell death and tumor immunity. In this study, we provided the first evidence of SLCO4C1 functioning as a tumor suppressor in HCC.

TRIM22 induces cellular senescence by targeting PHLPP2 in hepatocellular carcinoma

The ubiquitin-proteasome system is a vital protein degradation system that is involved in various cellular processes, such as cell cycle progression, apoptosis, and differentiation. Dysregulation of this system has been implicated in numerous diseases, including cancer, vascular disease, and neurodegenerative disorders. Induction of cellular senescence in hepatocellular carcinoma (HCC) is a potential anticancer strategy, but the precise role of the ubiquitin-proteasome system in cellular senescence remains unclear. In this study, we show that the E3 ubiquitin ligase, TRIM22, plays a critical role in the cellular senescence of HCC cells. TRIM22 expression is transcriptionally upregulated by p53 in HCC cells experiencing ionizing radiation (IR)-induced senescence. Overexpression of TRIM22 triggers cellular senescence by targeting the AKT phosphatase, PHLPP2. Mechanistically, the SPRY domain of TRIM22 directly associates with the C-terminal domain of PHLPP2, which contains phosphorylation sites that are subject to IKKβ-mediated phosphorylation. The TRIM22-mediated PHLPP2 degradation leads to activation of AKT-p53-p21 signaling, ultimately resulting in cellular senescence. In both human HCC databases and patient specimens, the levels of TRIM22 and PHLPP2 show inverse correlations at the mRNA and protein levels. Collectively, our findings reveal that TRIM22 regulates cancer cell senescence by modulating the proteasomal degradation of PHLPP2 in HCC cells, suggesting that TRIM22 could potentially serve as a therapeutic target for treating cancer.

A Novel Oncogenic Role of Disulfidptosis-related Gene SLC7A11 in Anti-tumor Immunotherapy Response to Human Cancers

BACKGROUND

The protein Solute Carrier Family 7 Member 11 (SLC7A11) plays a pivotal role in cellular redox homeostasis by suppressing disulfidptosis, which restricts tumor growth. Yet, its relevance in prognosis, immunity, and cancer treatment efficacy is not well understood.

METHODS

We conducted a comprehensive analysis of the expression of SLC7A11 across 33 cancer types, employing datasets from public databases. Methods, such as Cox regression and survival analyses assessed its prognostic significance, while functional enrichment explored the biological processes tied to SLC7A11. The association between SLC7A11 expression, immune cell infiltration, and immune-related gene expression was also scrutinized.

RESULTS

Notably, SLC7A11 expression was more pronounced in cancerous compared to normal samples and correlated with higher tumor grades. Increased SLC7A11 expression was linked to poor outcomes, particularly in liver hepatocellular carcinoma (LIHC). This protein's expression also showcased significant relationships with diverse molecular and immune subtypes. Additionally, a prognostic nomogram was devised, integrating SLC7A11 expression and clinical variables. High SLC7A11 levels corresponded with cell growth and senescence pathways in various cancers and with lipid and cholesterol metabolism in LIHC. Furthermore, potential therapeutic compounds for LIHC with high SLC7A11 were identified. Real-time PCR (qPCR) and Western blot were conducted to explore the expression of SLC7A11 in tumor tissues and cancer cell lines.

CONCLUSION

In summation, this study emphasizes the prognostic and immunological importance of SLC7A11, spotlighting its potential as a therapeutic target in LIHC.

Imatinib induces ferroptosis in gastrointestinal stromal tumors by promoting STUB1-mediated GPX4 ubiquitination

Imatinib (IM) has significantly improved the prognosis of gastrointestinal stromal tumor (GIST) patients, but some patients still have primary resistance to IM, and approximately half of patients develop acquired drug resistance within 2 years of treatment, necessitating exploration of new treatment strategies. Targeting ferroptosis as a novel approach to tumor treatment has gained attention. Yet, there is limited research on ferroptosis in GIST, and the underlying mechanism remains unclear. In this study, we revealed that IM increased lipid reactive oxygen species and intracellular Fe2+ levels, and decreased glutathione levels in GIST. This effect could be partially inhibited by Ferrostatin-1. Additionally, knocking down STUB1 and overexpressing GPX4 reversed the IM-induced ferroptosis effect. Moreover, STUB1 was identified as a novel E3 ubiquitin ligase of GPX4, promoting the ubiquitination at site K191 of GPX4. The combination of the GPX4 inhibitor RSL3 and IM synergistically induces ferroptosis, inhibiting GIST proliferation both in vivo and in vitro. Furthermore, STUB1 and GPX4 expression serve as independent prognostic factors for GIST. In conclusion, This study is the first to demonstrate that IM induces ferroptosis by promoting STUB1-mediated GPX4 ubiquitination in GIST, and the combination of RSL3 and IM emerges as a promising therapeutic strategy for GIST.

Targeting epigenetic and posttranslational modifications regulating ferroptosis for the treatment of diseases

Ferroptosis, a unique modality of cell death with mechanistic and morphological differences from other cell death modes, plays a pivotal role in regulating tumorigenesis and offers a new opportunity for modulating anticancer drug resistance. Aberrant epigenetic modifications and posttranslational modifications (PTMs) promote anticancer drug resistance, cancer progression, and metastasis. Accumulating studies indicate that epigenetic modifications can transcriptionally and translationally determine cancer cell vulnerability to ferroptosis and that ferroptosis functions as a driver in nervous system diseases (NSDs), cardiovascular diseases (CVDs), liver diseases, lung diseases, and kidney diseases. In this review, we first summarize the core molecular mechanisms of ferroptosis. Then, the roles of epigenetic processes, including histone PTMs, DNA methylation, and noncoding RNA regulation and PTMs, such as phosphorylation, ubiquitination, SUMOylation, acetylation, methylation, and ADP-ribosylation, are concisely discussed. The roles of epigenetic modifications and PTMs in ferroptosis regulation in the genesis of diseases, including cancers, NSD, CVDs, liver diseases, lung diseases, and kidney diseases, as well as the application of epigenetic and PTM modulators in the therapy of these diseases, are then discussed in detail. Elucidating the mechanisms of ferroptosis regulation mediated by epigenetic modifications and PTMs in cancer and other diseases will facilitate the development of promising combination therapeutic regimens containing epigenetic or PTM-targeting agents and ferroptosis inducers that can be used to overcome chemotherapeutic resistance in cancer and could be used to prevent other diseases. In addition, these mechanisms highlight potential therapeutic approaches to overcome chemoresistance in cancer or halt the genesis of other diseases.

The Mechanism of Ubiquitination or Deubiquitination Modifications in Regulating Solid Tumor Radiosensitivity

Radiotherapy, a treatment method employing radiation to eradicate tumor cells and subsequently reduce or eliminate tumor masses, is widely applied in the management of numerous patients with tumors. However, its therapeutic effectiveness is somewhat constrained by various drug-resistant factors. Recent studies have highlighted the ubiquitination/deubiquitination system, a reversible molecular modification pathway, for its dual role in influencing tumor behaviors. It can either promote or inhibit tumor progression, impacting tumor proliferation, migration, invasion, and associated therapeutic resistance. Consequently, delving into the potential mechanisms through which ubiquitination and deubiquitination systems modulate the response to radiotherapy in malignant tumors holds paramount significance in augmenting its efficacy. In this paper, we comprehensively examine the strides made in research and the pertinent mechanisms of ubiquitination and deubiquitination systems in governing radiotherapy resistance in tumors. This underscores the potential for developing diverse radiosensitizers targeting distinct mechanisms, with the aim of enhancing the effectiveness of radiotherapy.

Polyamines: their significance for maintaining health and contributing to diseases

Polyamines are essential for the growth and proliferation of mammalian cells and are intimately involved in biological mechanisms such as DNA replication, RNA transcription, protein synthesis, and post-translational modification. These mechanisms regulate cellular proliferation, differentiation, programmed cell death, and the formation of tumors. Several studies have confirmed the positive effect of polyamines on the maintenance of health, while others have demonstrated that their activity may promote the occurrence and progression of diseases. This review examines a variety of topics, such as polyamine source and metabolism, including metabolism, transport, and the potential impact of polyamines on health and disease. In addition, a brief summary of the effects of oncogenes and signaling pathways on tumor polyamine metabolism is provided. Video Abstract.

NFE2L1 restrains ferroptosis by transcriptionally regulating HJURP and participates in the progress of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a common head and neck malignancy with increasing mortality and high recurrence. In this work, we aim to explore the functional role of NFE2 like bZIP transcription factor 1 (NFE2L1) in OSCC progression. Based on databases analysis, we found that NFE2L1 was overexpressed in OSCC tumor tissues, and elevated NFE2L1 level induced poor prognosis of OSCC patients. Our results showed that NFE2L1 is upregulated in OSCC cells and overexpression of NFE2L1 promotes cell proliferation, and reduces the sensitivity of OSCC cells to erastin-induced ferroptosis. NFE2L1 upregulation decreased the levels of Fe2+, lipid reactive oxygen species and content of malondialdehyde, and increased the level of the key negative regulator of ferroptosis, GPX4 and SLC7A11. In NFE2L1 suppressed cells, these trends were reversed. Further results of dual luciferase reporter and chromatin immunoprecipitation assays confirmed that NFE2L1 could bind to the promoter of Holliday junction recognition protein (HJURP) to increase the transcriptional activity of HJURP, thus upregulating its expression. Inhibition of HJURP attenuated the proliferation and ferroptosis inhibition in NFE2L1 upregulated cells. In vivo tumorigenicity assay further proved that NFE2L1 promotes OSCC tumor growth. In summary, NFE2L1 restrains ferroptosis by transcriptionally regulating HJURP and participates in the progress of OSCC. Thus, NFE2L1 plays a key role in OSCC development and may be a promising therapeutic target for OSCC.

ATR-dependent ubiquitin-specific protease 20 phosphorylation confers oxaliplatin and ferroptosis resistance

Oxaliplatin (OXA) resistance is a major clinic challenge in hepatocellular carcinoma (HCC). Ferroptosis is a kind of iron-dependent cell death. Triggering ferroptosis is considered to restore sensitivity to chemotherapy. In the present study, we found that USP20 was overexpressed in OXA-resistant HCC cells. High expression of USP20 in HCC was associated with poor prognosis. USP20 contributes OXA resistance and suppress ferroptosis in HCC. Pharmacological inhibition or knockdown of USP20 triggered ferroptosis and increased the sensitivity of HCC cells to OXA both in vitro and in vivo. Coimmunoprecipitation results revealed that the UCH domain of USP20 interacted with the N terminal of SLC7A11. USP20 stabilized SLC7A11 via removing K48-linked polyubiquitination of SLC7A11 protein at K30 and K37. Most importantly, DNA damage-induced ATR activation was required for Ser132 and Ser368 phosphorylation of USP20. USP20 phosphorylation at Ser132 and Ser368 enhanced its stability and thus conferred OXA and ferroptosis resistance of HCC cells. Our study reveals a previously undiscovered association between OXA and ferroptosis and provides new insight into mechanisms regarding how DNA damage therapies always lead to therapeutic resistance. Therefore, targeting USP20 may mitigate the development of drug resistance and promote ferroptosis of HCC in patients receiving chemotherapy.

The ubiquitin-proteasome system links NADPH metabolism to ferroptosis

Ferroptosis is the type of cell death arising from uncontrolled and excessive lipid peroxidation. NADPH is essential for ferroptosis regulation because it supplies reducing equivalents for antioxidant defense systems and contributes to the generation of reactive oxygen species. Moreover, NADPH level serves as a biomarker for predicting the sensitivity of cells to ferroptosis. The ubiquitin-proteasome system governs the stability of many ferroptosis effectors. Recent research has revealed MARCHF6, the endoplasmic reticulum ubiquitin ligase, as an unprecedented NADPH sensor in the ubiquitin system and a critical regulator of ferroptosis involved in tumorigenesis and fetal development. This review summarizes the current understanding of NADPH metabolism and the ubiquitin-proteasome system in regulating ferroptosis and highlights the emerging importance of MARCHF6 as a vital connector between NADPH metabolism and ferroptosis.

CTRP6 protects against ferroptosis to drive lung cancer progression and metastasis by destabilizing SOCS2 and augmenting the xCT/GPX4 pathway

Lung cancer is a highly heterogeneous malignancy, and despite the rapid development of chemotherapy and radiotherapy, acquired drug resistance and tumor progression still occur. Thus, it is urgent to identify novel therapeutic targets. Our research aims to screen novel biomarkers associated with the prognosis of lung carcinoma patients and explore the potential regulatory mechanisms. We obtained RNA sequencing (RNA-seq) data of lung cancer patients from public databases. Clinical signature analysis, weighted gene coexpression network analysis (WGCNA) and the random forest algorithm showed that C1q/tumor necrosis factor-related protein-6 (CTRP6) is a core gene related to lung cancer prognosis, and it was determined to promote tumor proliferation and metastasis both in vivo and in vitro. Mechanistically, silencing CTRP6 was determined to promote xCT/GPX4-involved ferroptosis through functional assays related to lipid peroxidation, Fe2+ concentration and mitochondrial ultrastructure. By performing interactive proteomics analyses in lung tumor cells, we identified the interaction between CTRP6 and suppressor of cytokine signaling 2 (SOCS2) leading to SOCS2 ubiquitination degradation, subsequently enhancing the downstream xCT/GPX4 signaling pathway. Moreover, significant correlations between CTRP6-mediated SOCS2 and ferroptosis were revealed in mouse models and clinical specimens of lung cancer. As inducing ferroptosis has been gradually regarded as an alternative strategy to treat tumors, targeting CTRP6-mediated ferroptosis could be a potential strategy for lung cancer therapy.

METTL9-SLC7A11 axis promotes hepatocellular carcinoma progression through ferroptosis inhibition

Methytransferase-like proteins 9 (METTL9) has been characterized as an oncogene in several cancers, however, its role in hepatocellular carcinoma (HCC) remains unknown. Here, we investigated the function and molecular mechanism of METTL9 in HCC. We showed that METTL9 expression was elevated in HCC, and its high expression was associated with poor survival outcomes. Knockdown of METTL9 observed a significant inhibition of HCC cell viability, migration, and invasion both in vitro and in vivo. By contrast, METTL9 overexpression HCC cells obtained stronger abilities in cell proliferation and migration. Mechanistically, we discovered that METTL9 knockdown led to a reduction in the expression level of SLC7A11, a key suppressor of ferroptosis, in turn, promoted ferroptosis in HCC cells, impeding the progression of HCC. Moreover, we have proved that targeting METTL9 could significantly restrain the growth of HCC patient-derived xenograft (PDX). Our study established METTL9 as a critical role in promoting HCC development and provides a foundation for further investigation and potential therapeutic interventions targeting ferroptosis in HCC.

Brusatol induces ferroptosis in oesophageal squamous cell carcinoma by repressing GSH synthesis and increasing the labile iron pool via inhibition of the NRF2 pathway

Brusatol (Bru), a bioactive compound found in Brucea sumatrana, exerts antitumour effects on several malignancies. However, the role and molecular mechanism of Bru in squamous cell carcinoma of the oesophagus (ESCC) remain unclear. Here, we found that Bru decreased the survival of ESCC cells. Subsequently, the ferroptosis inhibitors, deferoxamine and liproxstatin-1, rescued Bru-induced cell death, indicating that ferroptosis plays a major role in Bru-induced cell death. Furthermore, Bru promoted lipid peroxidation, glutathione (GSH) depletion, and ferrous iron overload in vitro. Consistent with these in vitro results, Bru significantly inhibited tumour growth in KYSE150 xenograft nude mice by triggering ferroptosis. Mechanistically, nuclear factor E2-related factor 2 (NRF2) inactivation via increased ubiquitin-proteasome degradation was found to be a vital determinant of ferroptosis induced by Bru. Notably, Bru significantly decreases GSH synthesis, iron storage, and efflux by downregulating the expression of NRF2 target genes (glutamate-cysteine ligase catalytic subunit (GCLC), solute carrier family 7 member 11 (SLC7A11), ferritin heavy chain 1 (FTH1), and solute carrier family 40 member 1 (SLC40A1)), resulting in the accumulation of lethal lipid-based reactive oxygen species (ROS) and intracellular enrichment of chelated iron. Taken together, our findings indicate that ferroptosis is a novel mechanism underlying Bru-induced antitumour activity and will hopefully provide a valuable compound for ESCC treatment.

The E3 ligase TRIM26 suppresses ferroptosis through catalyzing K63-linked ubiquitination of GPX4 in glioma

The selenium-containing enzyme GPX4 moonlights as a central regulator of ferroptosis, an iron-dependent, nonapoptotic form of regulated cell death caused by lipid peroxidation. Yet, little is known about the mechanisms underlying the regulation of its post-transcriptional modifications. Here, we identify the tripartite motif-containing protein TRIM26 as an E3 ubiquitin ligase of GPX4. TRIM26 directly interacts with GPX4 through its Ring domain and catalyzes the ubiquitination of GPX4 at K107 and K117, which promotes the switch in polyubiquitination of GPX4 from K48 to K63, thus enhancing GPX4 protein stability. Moreover, PLK1-mediated S127 phosphorylation of TRIM26 enhances the interaction between TRIM26 and GPX4. Inhibition of TRIM26 phosphorylation causes a reduction in GPX4 K63-linked polyubiquitination and diminishes GPX4 protein levels in tumor cells. Further investigation revealed that TRIM26 is overexpressed in glioma cells. TRIM26 silencing dramatically impedes ferroptosis resistance and tumorigenesis in glioma in vivo and in vitro. Clinically, TRIM26 expression shows a direct correlation with GPX4 and PLK1 levels in glioma samples and is associated with poor outcome in patients with glioma. Collectively, these findings define the role of GPX4 K63-linked polyubiquitination in ferroptosis and suggest a potential strategy for glioma treatment.

AP4M1 as a prognostic biomarker associated with cell proliferation, migration and immune regulation in hepatocellular carcinoma

BACKGROUND

AP4M1 is a protein-coding gene that plays a crucial role in transporter activity, recognition, and hereditary-associated diseases, but it's largely unknown in cancers.

METHODS

The expression level of AP4M1 in cancers was investigated by The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, and the correlation between AP4M1 and hepatocellular carcinoma (HCC) clinicopathological parameters were analyzed. Univariate and multifactorial COX regression analyses were performed to clarify the prognostic value of AP4M1 in HCC. The correlation between AP4M1 and immune cell infiltration was analyzed using single-sample Gene Set Enrichment Analysis (ssGSEA). Besides, we verified the biological function of AP4M1 by applying Cell Counting Kit-8 (CCK8), colony formation, and transwell assays.

RESULTS

The expression of AP4M1 was significantly elevated in HCC and was correlated with patients' pathological grades, AFP, and BMI. Kaplan-Meier survival curves indicated that patients with AP4M1 overexpression had worse overall survival. Univariate and multivariate COX regression analyses showed that AP4M1 was an independent risk factor affecting the prognosis of HCC. In addition, we observed that AP4M1 positively correlated with most immune checkpoint suppressor genes in HCC. Moreover, in vitro experiments further confirmed that AP4M1 could promote the proliferation and invasion of HCC.

CONCLUSIONS

AP4M1 is highly expressed and associated with poor prognosis in HCC. AP4M1 is closely related to cancer-immune regulation and could be a novel target for HCC, and guiding new strategies for the diagnosis and treatment of HCC patients.

Recent advances of ferroptosis in tumor: From biological function to clinical application

Ferroptosis is a recently recognized form of cell death with distinct features in terms of morphology, biochemistry, and molecular mechanisms. Unlike other types of cell death, ferroptosis is characterized by iron dependence, reactive oxygen species accumulation and lipid peroxidation. Recent studies have demonstrated that selective autophagy plays a vital role in the induction of ferroptosis, including ferritinophagy, lipophagy, clockophagy, and chaperone-mediated autophagy. Emerging evidence has indicated the involvement of ferroptosis in tumorigenesis through regulating various biological processes, including tumor growth, metastasis, stemness, drug resistance, and recurrence. Clinical and preclinical studies have found that novel therapies targeting ferroptosis exert great potential in the treatment of tumors. This review provides a comprehensive overview of the molecular mechanisms in ferroptosis, especially in autophagy-driven ferroptosis, discusses the recent advances in the biological roles of ferroptosis in tumorigenesis, and highlights the application of novel ferroptosis-targeted therapies in the clinical treatment of tumors.

AMER1 deficiency promotes the distant metastasis of colorectal cancer by inhibiting SLC7A11- and FTL-mediated ferroptosis

The crosstalk between ferroptosis and cancer metastasis remains unclear. Here, we identify AMER1 as a key regulator of ferroptosis. AMER1 loss causes resistance to ferroptosis in colorectal cancer (CRC) cells. Interestingly, AMER1-deficient CRC cells preferentially form distant metastases, while AMER1-naive CRC cells mainly invade lymph nodes. Moreover, the ferroptosis inhibitor liproxstatin-1 effectively promotes hematogenous transfer of AMER1-naive cells. Mechanistically, AMER1 binds to SLC7A11 and ferritin light chain (FTL) and recruits β-TrCP1/2, which degrade SLC7A11 and FTL by ubiquitination. Therefore, AMER1 deficiency increases cellular cystine levels but decreases the pool of labile free iron, thereby enhancing resistance to ferroptosis in CRC cells. Thus, AMER1 deficiency increases the survival of CRC cells in the blood under conditions of high oxidative stress and then promotes hematogenous metastasis of CRC. In conclusion, AMER1 mediates the crosstalk between ferroptosis and cancer metastasis, which provides a window of opportunity for treating metastatic colorectal cancer patients with AMER1 mutations.

Ferroptosis regulator NOS2 is closely associated with the prognosis and cell malignant behaviors of hepatoblastoma: a bioinformatic and in vitro study

Background

Hepatoblastoma (HB) is the most common liver tumor in children with easy metastasis. The emergence of ferroptosis as a novel form of cell death has gained increased attention in various human cancers. However, the roles of ferroptosis-related (FR) genes in HB remain elusive.

Methods

The GSE133039, GSE131329, and GSE81928 datasets were utilized for screening core FR genes in HB. Through Lasso regression analysis and using the support vector machine recursive feature elimination (SVM-RFE) algorithm, three candidate FR genes were obtained for characterizing HB. Their expression patterns and their clinical associations were explored through the 'Limma' R package, and their diagnostic potential was evaluated using ROC curves. Nitric oxide synthase 2 (NOS2) emerged as a candidate for further analyses. The CIBERSORT algorithm and GSEA dataset were used to respectively investigate the immune and metabolism effects of NOS2; the former was validated through immunofluorescence. The GSDC database was employed to analyze the correlation between NOS2 expression and the therapeutic efficacy of multiple drugs. PCR, Western blotting, colony formation assays, and Transwell experiments, were used to determine biological functions of NOS2 in HB cells. Potential upstream transcription factors of NOS2 were predicted through the TRRUST, hTFtarget, GeneCards, and JASPAR databases.

Results

NQO1, SLC1A4, and NOS2 were identified as potential genes in HB and found to be significantly upregulated in tumor samples. Nevertheless, only NOS2 was closely associated with HB clinicopathological characteristics; high NOS2 expression indicated poor prognosis, metastatic tendency, and late clinical stage. Immune analyses indicated that high NOS2 expression was concomitant with decreased infiltration levels of CD8+ T cells but increased infiltration levels of macrophages. GSEA revealed that NOS2 failed to affect the enrichments of glycolysis, fatty acid metabolism, and cholesterol biosynthesis in HB. Moreover, NOS2 was positively correlated with the IC50 values of trametinib, lapatinib, and cisplatin. NOS2 overexpression promoted the proliferation, migration and invasion of HepG2 and HuH-6 cells. JUND was identified as a potential transcriptional regulator of NOS2 by binding to its promoter (5'-TTCTGACTCTTTT-3').

Conclusion

NOS2 plays a significant role in HB clinical assessments and holds promise as a novel therapeutic target.

Regulation of m6A modification on ferroptosis and its potential significance in radiosensitization

Radiotherapy is often used to treat various types of cancers, but radioresistance greatly limits the clinical efficiency. Recent studies have shown that radiotherapy can lead to ferroptotic cancer cell deaths. Ferroptosis is a new type of programmed cell death caused by excessive lipid peroxidation. The induction of ferroptosis provides a potential therapeutic strategy for radioresistance. As the most common post-transcriptional modification of mRNA, m6A methylation is widely involved in the regulation of various physiopathological processes by regulating RNA function. Dynamic m6A modification controlled by m6A regulatory factors also affects the susceptibility of cells to ferroptosis, thereby determining the radiosensitivity of tumor cells to radiotherapy. In this review, we summarize the mechanism and significance of radiotherapy induced ferroptosis, analyze the regulatory characteristics of m6A modification on ferroptosis, and discuss the possibility of radiosensitization by enhancing m6A-mediated ferroptosis. Clarifying the regulation of m6A modification on ferroptosis and its significance in the response of tumor cells to radiotherapy will help us identify novel targets to improve the efficacy of radiotherapy and reduce or overcome radioresistance.

Ferroptosis, Necroptosis, and Pyroptosis in Gastrointestinal Cancers: The Chief Culprits of Tumor Progression and Drug Resistance

In recent years, the incidence of gastrointestinal cancers is increasing, particularly in the younger population. Effective treatment is crucial for improving patients' survival outcomes. Programmed cell death, regulated by various genes, plays a fundamental role in the growth and development of organisms. It is also critical for maintaining tissue and organ homeostasis and takes part in multiple pathological processes. In addition to apoptosis, there are other types of programmed cell death, such as ferroptosis, necroptosis, and pyroptosis, which can induce severe inflammatory responses. Notably, besides apoptosis, ferroptosis, necroptosis, and pyroptosis also contribute to the occurrence and development of gastrointestinal cancers. This review aims to provide a comprehensive summary on the biological roles and molecular mechanisms of ferroptosis, necroptosis, and pyroptosis, as well as their regulators in gastrointestinal cancers and hope to open up new paths for tumor targeted therapy in the near future.

CircRREB1 mediates lipid metabolism related senescent phenotypes in chondrocytes through FASN post-translational modifications

Osteoarthritis is a prevalent age-related disease characterized by dysregulation of extracellular matrix metabolism, lipid metabolism, and upregulation of senescence-associated secretory phenotypes. Herein, we clarify that CircRREB1 is highly expressed in secondary generation chondrocytes and its deficiency can alleviate FASN related senescent phenotypes and osteoarthritis progression. CircRREB1 impedes proteasome-mediated degradation of FASN by inhibiting acetylation-mediated ubiquitination. Meanwhile, CircRREB1 induces RanBP2-mediated SUMOylation of FASN and enhances its protein stability. CircRREB1-FASN axis inhibits FGF18 and FGFR3 mediated PI3K-AKT signal transduction, then increased p21 expression. Intra-articular injection of adenovirus-CircRreb1 reverses the protective effects in CircRreb1 deficiency mice. Further therapeutic interventions could have beneficial effects in identifying CircRREB1 as a potential prognostic and therapeutic target for age-related OA.

Long noncoding RNA CASC11 suppresses sorafenib-triggered ferroptosis via stabilizing SLC7A11 mRNA in hepatocellular carcinoma cells

As a frontline treatment for patients with advanced hepatocellular carcinoma (HCC), sorafenib is an effective drug approved by the Food and Drug Administration (FDA). Ferroptosis, a newly defined programmed cell death process with the hallmark of the accumulation of iron-dependent lipid peroxides, can be induced by sorafenib treatment. Our previous study identified oncogenic roles of long noncoding RNA (lncRNA) Cancer susceptibility candidate 11 (CASC11) in HCC progression. However, the relationship between CASC11 and sorafenib-induced ferroptosis in HCC remains unclear. In the present study, we aim to investigate the role of CASC11 in sorafenib-induced ferroptosis in HCC cell lines and determine the involved molecular mechanisms. Here, we demonstrated that sorafenib decreased CASCL11 expression. Knockdown of CASC11 enhanced sorafenib-induced ferroptosis, while overexpression of CASC11 exerted the opposite effect in HCC cells. Moreover, CASC11 led to the accumulation of intracellular malondialdehyde (MDA), lipid reactive oxygen species (ROS) and Fe2+ while depleting glutathione (GSH), thereby suppressing sorafenib-induced ferroptosis and cell death. Ferrostatin-1 (Ferr-1), a ferroptosis inhibitor, reversed the enhanced anticancer effect of sorafenib caused by the silence of CASC11 in HCC cells. Mechanistically, CASC11 upregulated the expression of solute carrier family 7 member 11 (SLC7A11) which is critical for ferroptosis inhibition. CASC11 associated with and stabilized SLC7A11 mRNA. In summary, our data revealed, for the first time, that CASC11 inhibits the sorafenib-induced ferroptosis in HCC cells via regulating SLC7A11, providing a new basis for clinical therapeutic strategies for patients with HCC.

Comprehensive analysis of suppressor of cytokine signaling 2 protein in the malignant transformation of NSCLC

Suppressor of cytokine signaling 2 (SOCS2) plays an essential role in a number of physiological phenomena and functions as a tumor suppressor. Understanding the predictive effects of SOCS2 on non-small cell lung cancer (NSCLC) is urgently needed. The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases were used to assess SOCS2 gene expression levels in NSCLC. The clinical significance of SOCS2 was evaluated through Kaplan-Meier curve analysis and the analysis of related clinical factors. Gene Set Enrichment Analysis (GSEA) was used to identify the biological functions of SOCS2. Subsequently proliferation, wound-healing, colony formation and Transwell assays, and carboplatin drug experiments were used for verification. The results revealed that SOCS2 expression was low in the NSCLC tissues of patients in TCGA and GEO database analyses. Downregulated SOCS2 was associated with poor prognosis, as determined by Kaplan-Meier survival analysis (HR 0.61, 95% CI 0.52-0.73; P<0.001). GSEA showed that SOCS2 was involved in intracellular reactions, including epithelial-mesenchymal transition (EMT). Cell experiments indicated that knockdown of SOCS2 caused the malignant progression of NSCLC cell lines. Furthermore, the drug experiment showed that silencing of SOCS2 promoted the resistance of NSCLC cells to carboplatin. In conclusion, low expression of SOCS2 was associated with poor clinical prognosis by effecting EMT and causing drug resistance in NSCLC cell lines. Furthermore, SOCS2 could act as a predictive indicator for NSCLC.