Ironing out the role of ferroptosis in immunity.

Ferroptosis is a type of regulated cell death that drives the pathophysiology of many diseases. Oxidative stress is detectable in many types of regulated cell death, but only ferroptosis involves lipid peroxidation and iron dependency. Ferroptosis originates and propagates from several organelles, including the mitochondria, endoplasmic reticulum, Golgi, and lysosomes. Recent data have revealed that immune cells can both induce and undergo ferroptosis. A mechanistic understanding of how ferroptosis regulates immunity is critical to understanding how ferroptosis controls immune responses and how this is dysregulated in disease. Translationally, more work is needed to produce ferroptosis-modulating immunotherapeutics. This review focuses on the role of ferroptosis in immune-related diseases, including infection, autoimmune diseases, and cancer. We discuss how ferroptosis is regulated in immunity, how this regulation contributes to disease pathogenesis, and how targeting ferroptosis may lead to novel therapies.

Signals of pseudo-starvation unveil the amino acid transporter SLC7A11 as key determinant in the control of Treg cell proliferative potential.

Human CD4+CD25hiFOXP3+ regulatory T (Treg) cells are key players in the control of immunological self-tolerance and homeostasis. Here, we report that signals of pseudo-starvation reversed human Treg cell in vitro anergy through an integrated transcriptional response, pertaining to proliferation, metabolism, and transmembrane solute carrier transport. At the molecular level, the Treg cell proliferative response was dependent on the induction of the cystine/glutamate antiporter solute carrier (SLC)7A11, whose expression was controlled by the nuclear factor erythroid 2-related factor 2 (NRF2). SLC7A11 induction in Treg cells was impaired in subjects with relapsing-remitting multiple sclerosis (RRMS), an autoimmune disorder associated with reduced Treg cell proliferative capacity. Treatment of RRMS subjects with dimethyl fumarate (DMF) rescued SLC7A11 induction and fully recovered Treg cell expansion. These results suggest a previously unrecognized mechanism that may account for the progressive loss of Treg cells in autoimmunity and unveil SLC7A11 as major target for the rescue of Treg cell proliferation.

Kynurenine importation by SLC7A11 propagates anti-ferroptotic signaling.

IDO1 oxidizes tryptophan (TRP) to generate kynurenine (KYN), the substrate for 1-carbon and NAD metabolism, and is implicated in pro-cancer pathophysiology and infection biology. However, the mechanistic relationships between IDO1 in amino acid depletion versus product generation have remained a longstanding mystery. We found an unrecognized link between IDO1 and cell survival mediated by KYN that serves as the source for molecules that inhibit ferroptotic cell death. We show that this effect requires KYN export from IDO1-expressing cells, which is then available for non-IDO1-expressing cells via SLC7A11, the central transporter involved in ferroptosis suppression. Whether inside the "producer" IDO1+ cell or the "receiver" cell, KYN is converted into downstream metabolites, suppressing ferroptosis by ROS scavenging and activating an NRF2-dependent, AHR-independent cell-protective pathway, including SLC7A11, propagating anti-ferroptotic signaling. IDO1, therefore, controls a multi-pronged protection pathway from ferroptotic cell death, underscoring the need to re-evaluate the use of IDO1 inhibitors in cancer treatment.

The CRL3KCTD10 ubiquitin ligase-USP18 axis coordinately regulates cystine uptake and ferroptosis by modulating SLC7A11.

SLC7A11 is a cystine transporter and ferroptosis inhibitor. How the stability of SLC7A11 is coordinately regulated in response to environmental cystine by which E3 ligase and deubiquitylase (DUB) remains elusive. Here, we report that neddylation inhibitor MLN4924 increases cystine uptake by causing SLC7A11 accumulation, via inactivating Cullin-RING ligase-3 (CRL-3). We identified KCTD10 as the substrate-recognizing subunit of CRL-3 for SLC7A11 ubiquitylation, and USP18 as SLC7A11 deubiquitylase. Upon cystine deprivation, the protein levels of KCTD10 or USP18 are decreased or increased, respectively, contributing to SLC7A11 accumulation. By destabilizing or stabilizing SLC7A11, KCTD10, or USP18 inversely regulates the cystine uptake and ferroptosis. Biologically, MLN4924 combination with SLC7A11 inhibitor Imidazole Ketone Erastin (IKE) enhanced suppression of tumor growth. In human breast tumor tissues, SLC7A11 levels were negatively or positively correlated with KCTD10 or USP18, respectively. Collectively, our study defines how SLC7A11 and ferroptosis is coordinately regulated by the CRL3KCTD10/E3-USP18/DUB axis, and provides a sound rationale of drug combination to enhance anticancer efficacy.

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.

A novel link between circPDE3B and ferroptosis in esophageal squamous cell carcinoma progression.

AIM: To unravel whether ferroptosis involves with the actions by circPDE3B-mediated facilitation of esophageal squamous cell carcinoma (ESCC) progression. METHODS: Human ESCC tissues and cell lines were prepared for the evaluation of ferroptosis. Cellular iron, ROS, GSH, and MDA levels were measured to assess ferroptosis. Flow cytometry was employed to analyze apoptosis and cell cycle. Subcellular fractionation and fluorescence in situ hybridization (FISH) were conducted to validate the localization of circPDE3B. RNA pull-down, RNA immunoprecipitation (RIP), and luciferase assay were subjected to identify the molecular mechanisms. Nude mouse xenograft model was carried out to evaluate the function of circPDE3B/SLC7A11/CBS in vivo. RESULTS: Increased circPDE3B in human ESCC specimens was positively correlated with ferroptosis-related molecules, SLC7A11 and CBS. Functionally, circPDE3B knockdown triggered ferroptosis, apoptosis, and cell cycle arrest in ESCC cells. Whereas, these effects were obviously blocked by miR-516b-5p inhibitor. Mechanistically, not only circPDE3B sponged miR-516b-5p to upregulate CBS, but also directly bound with HNRNPK to stabilize SLC7A11. In mice, depletion of circPDE3B restrained ESCC growth, while this was abolished by overexpression of CBS or SLC7A11. CONCLUSION: In summary, circPDE3B promotes ESCC progression by suppressing ferroptosis through recruiting HNRNPK/SLC7A11 and miR-516b-5p/CBS axes.

Identification of SLC7A11-AS1/SLC7A11 pair as a ferroptosis-related therapeutic target for hepatocellular carcinoma.

Hepatocellular carcinoma (HCC), a prevalent malignancy worldwide, poses significant challenges in terms of prognosis, necessitating innovative therapeutic approaches. Ferroptosis offers notable advantages over apoptosis, holding promise as a novel therapeutic approach for HCC complexities. Moreover, while the interaction between long non-coding RNAs (lncRNAs) and mRNAs is pivotal in various physiological and pathological processes, their involvement in ferroptosis remains relatively unexplored. In this study, we constructed a ferroptosis-related lncRNA-mRNA correlation network in HCC using Pearson correlation analysis. Notably, the SLC7A11-AS1/SLC7A11 pair, exhibiting high correlation, was identified. Bioinformatics analysis revealed a significant correlation between the expression levels of this pair and key clinical characteristics of HCC patients, including gender, pathology, Ishak scores and tumour size. And poor prognosis was associated with high expression of this pair. Functional experiments demonstrated that SLC7A11-AS1, by binding to the 3'UTR region of SLC7A11 mRNA, enhanced its stability, thereby promoting HCC cell growth and resistance to erastin- induced ferroptosis. Additionally, in vivo studies confirmed that SLC7A11-AS1 knockdown potentiated the inhibitory effects of erastin on tumour growth. Overall, our findings suggest that targeting the SLC7A11-AS1/SLC7A11 pair holds promise as a potential therapeutic strategy for HCC patients.

IL4i1 and IDO1: Oxidases that control a tryptophan metabolic nexus in cancer.

Regulated tryptophan metabolism by immune cells has been associated with the promotion of tolerance and poor outcomes in cancer. The main focus of research has centered on local tryptophan depletion by IDO1, an intracellular heme-dependent oxidase that converts tryptophan to formyl-kynurenine. This is the first step of a complex pathway supplying metabolites for de novo NAD+ biosynthesis, 1-carbon metabolism, and a myriad of kynurenine derivatives of which several act as agonists of the arylhydrocarbon receptor (AhR). Thus, cells that express IDO1 deplete tryptophan while generating downstream metabolites. We now know that another enzyme, the secreted L-amino acid oxidase IL4i1 also generates bioactive metabolites from tryptophan. In tumor microenvironments, IL4i1 and IDO1 have overlapping expression patterns, especially in myeloid cells, suggesting the two enzymes control a network of tryptophan-specific metabolic events. New findings about IL4i1 and IDO1 have shown that both enzymes generate a suite of metabolites that suppress oxidative cell death ferroptosis. Thus, within inflammatory environments, IL4i1 and IDO1 simultaneously control essential amino acid depletion, AhR activation, suppression of ferroptosis, and biosynthesis of key metabolic intermediates. Here, we summarize the recent advances in this field, focusing on IDO1 and IL4i1 in cancer. We speculate that while inhibition of IDO1 remains a viable adjuvant therapy for solid tumors, the overlapping effects of IL4i1 must be accounted for, as potentially both enzymes may need to be inhibited at the same time to produce positive effects in cancer therapy.

NAT10 inhibition promotes ac4C-dependent ferroptosis to counteract sorafenib resistance in nasopharyngeal carcinoma.

Sorafenib, an anticancer drug, has been shown to induce ferroptosis in cancer cells. However, resistance to sorafenib greatly limits its therapeutic efficacy, and the exact mechanism of resistance is not fully understood. This study investigated the role of N-Acetyltransferase 10 (NAT10) in influencing the anticancer activity of sorafenib in nasopharyngeal carcinoma (NPC) and its molecular mechanism. NAT10 expression was significantly upregulated in NPC. Mechanistically, NAT10 promotes proteins of solute carrier family 7 member 11 (SLC7A11) expression through ac4C acetylation, inhibiting sorafenib-induced ferroptosis in NPC cells. The combined application of sorafenib and the NAT10 inhibitor remodelin significantly inhibits SLC7A11 expression and promotes ferroptosis in NPC cells. In vivo knockout of NAT10 inhibited the growth of sorafenib-resistant NPC. Our findings suggest that NAT10 inhibition might be a promising therapeutic approach to enhance the anticancer activity of sorafenib.

Multiple myeloma with high expression of SLC7A11 is sensitive to erastin-induced ferroptosis.

Ferroptosis, a nonapoptotic form of cell death marked by iron-dependent peroxidation of phospholipids, is associated with the occurrence and progression of tumors. Erastin, a selective inhibitor of the cystine/glutamate transporter system Xc-, can induce the ferroptosis of cancer cells. Multiple myeloma (MM) has been reported to be insensitive to erastin-induced ferroptosis. However, we found the erastin sensitivity of different MM cells varied widely. Specifically, SLC7A11 abundance determined the sensitivity of MM cells to erastin-induced ferroptosis. MM cells expressing a high SLC7A11 level were more sensitive to erastin-induced ferroptosis than cells expressing a low level of SLC7A11. Moreover, the expression of SLC7A11 gradually increased with the progression of plasma cell dyscrasias. Survival analysis indicated that high levels of SLC7A11 predicted a poor prognosis for MM patients. Knocking down SLC7A11 expression significantly inhibited the proliferation of MM cells and induced ferroptotic cell death. Additionally, we revealed that the long noncoding RNA (lncRNA) SLC7A11-AS1 was a critical regulatory factor of SLC7A11 expression. SLC7A11-AS1 overexpression diminished SLC7A11 levels, leading to the ferroptosis of MM cells. In summary, our data show that heterogeneous SLC7A11 expression affects MM cell sensitivity to ferroptosis, providing a theoretical basis for improving the clinical treatment of MM.

Disulfidptosis: A new type of cell death.

Disulfidptosis is a novel form of cell death that is distinguishable from established programmed cell death pathways such as apoptosis, pyroptosis, autophagy, ferroptosis, and oxeiptosis. This process is characterized by the rapid depletion of nicotinamide adenine dinucleotide phosphate (NADPH) in cells and high expression of solute carrier family 7 member 11 (SLC7A11) during glucose starvation, resulting in abnormal cystine accumulation, which subsequently induces andabnormal disulfide bond formation in actin cytoskeleton proteins, culminating in actin network collapse and disulfidptosis. This review aimed to summarize the underlying mechanisms, influencing factors, comparisons with traditional cell death pathways, associations with related diseases, application prospects, and future research directions related to disulfidptosis.

C-FOS inhibition promotes pancreatic cancer cell ferroptosis by transcriptionally regulating the expression of SLC7A11.

Cellular proto-oncogene C-Fos forms the AP-1 transcription factor by dimerizing with proto-oncogene c-Jun; this factor upregulates the transcription of genes associated with different malignancies. However, its functions in pancreatic adenocarcinoma (PAAD) remain poorly understood. In this study, the c-Fos was increased in PAAD cells and tissues through bioinformatic analysis, RT-PCR, and WB. In two PAAD cell lines, PANC-1 and BxPC-3, we performed c-Fos knockdown studies using short hairpin RNA (shRNA). Functional analysis indicated that c-Fos depletion in PAAD cells inhibits cell proliferation and promotes ferroptosis. Chromatin Immunoprecipitation (ChIP) and Dual-luciferase experiments showed that c-Fos coupled to the promoter region of SLC7A11 stimulated its transcription, providing mechanistic insight into the process. Moreover, SLC7A11 blocked the decline of proliferation and ferroptosis by c-Fos knockdown in PAAD cells. Furthermore, a xenograft nude mouse model was established to study the impact of c-Fos on tumorigenesis in vivo. Depletion of c-Fos could suppress PC tumor growth and the expressions of SLC7A11, ki-67, and 4HNE, but overexpression of SLC7A11 reversed this process. In summary, our investigation has shown that c-Fos acts as a transcriptional regulator of SLC7A11, which may enhance tumour growth in pancreatic cancer by inhibiting ferroptosis. These results indicate that c-Fos might be a promising target for treating ferroptosis in PAAD.

LINC00942 inhibits ferroptosis and induces the immunosuppression of regulatory T cells by recruiting IGF2BP3/SLC7A11 in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a common malignant tumor with a high recurrence rate and a poor prognosis. Long intergenic nonprotein coding RNA 942 (LINC00942) is reported to be related to ferroptosis and the immune response in HCC and serves as an oncogene in various cancers. This research aimed to explore the contribution of LINC00942 in HCC progression. Functional assays were used to evaluate the functional role of LINC00942 in vitro and in vivo. Mechanistic assays were conducted to assess the association of LINC00942 with insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3) and solute carrier family 7 member 11 (SLC7A11) and the regulatory pattern of LINC00942 in HCC cells. LINC00942 was found to exhibit upregulation in HCC tissue and cells. LINC00942 facilitated HCC cell proliferation, suppressed ferroptosis, and converted naive CD4+ T cells to inducible Treg (iTreg) cells by regulating SLC7A11. Furthermore, SLC7A11 expression was positively modulated by LINC00942 in HCC cells. IGF2BP3 was a shared RNA-binding protein (RBP) for LINC00942 and SLC7A11. The binding between the SLC7A11 3' untranslated region and IGF2BP3 was verified, and LINC00942 was found to recruit IGF2BP3 to promote SLC7A11 mRNA stability in an m6A-dependent manner. Moreover, mouse tumor growth and proliferation were inhibited, and the number of FOXP3+CD25+ T cells was increased, while ferroptosis was enhanced after LINC00942 knockdown in vivo. LINC00942 suppresses ferroptosis and induces Treg immunosuppression in HCC by recruiting IGF2BP3 to enhance SLC7A11 mRNA stability, which may provide novel therapeutic targets for HCC.

Redox-dependent AMPK inactivation disrupts metabolic adaptation to glucose starvation in xCT-overexpressing cancer cells.

Accelerated aerobic glycolysis is a distinctive metabolic property of cancer cells that confers dependency on glucose for survival. However, the therapeutic strategies targeting this vulnerability are still inefficient and have unacceptable side effects in clinical trials. Therefore, developing biomarkers to predict therapeutic efficacy would be essential to improve the selective targeting of cancer cells. Here, we found that cell lines that are sensitive to glucose deprivation have high expression of cystine/glutamate antiporter xCT (also known as SLC7A11). We found that cystine uptake and glutamate export through xCT contributed to rapid NADPH depletion under glucose deprivation. This collapse of the redox system oxidized and inactivated AMP-activated protein kinase (AMPK), a major regulator of metabolic adaptation, resulting in a metabolic catastrophe and cell death. Although this phenomenon was prevented by pharmacological or genetic inhibition of xCT, overexpression of xCT sensitized resistant cancer cells to glucose deprivation. Taken together, these findings suggest a novel crosstalk between AMPK and xCT that links metabolism and signal transduction, and reveal a metabolic vulnerability to glucose deprivation in cancer cells expressing high levels of xCT.

Non-cytotoxic nanomolar concentration of arctigenin protects neuronal cells from chemotherapy-induced ferroptosis by regulating SLC7A11-cystine-cysteine axis.

Neurotoxicity is a common side effect of certain types of therapeutic drugs, posing a major hurdle for their clinical application. Accumulating evidence suggests that ferroptosis is involved in the neurotoxicity induced by these drugs. Therefore, targeting ferroptosis is considered to be a reasonable approach to prevent such side effect. Arctigenin (ATG) is a major bioactive ingredient of Arctium lappa L., a popular medicinal plant in Asia, and has been reported to have multiple bioactivities including neuroprotection. However, the mechanisms underlying the neuroprotection of ATG has not been well elucidated. The purpose of this study was to investigate whether the neuroprotection of ATG was associated with its ability to protect neuronal cells from ferroptosis. Using neuronal cell ferroptosis model induced by either classic ferroptosis induces or therapeutic drugs, we demonstrated for the first time that ATG in the nanomolar concentration range effectively prevented neuronal cell ferroptosis induced by classic ferroptosis inducer sulfasalazine (SAS) and erastin (Era), or therapeutic drug oxaliplatin (OXA) and 5-fluorouracil (5-FU). Mechanistically, we uncovered that the anti-ferroptotic effect of ATG was attributed to its ability to activate SLC7A11-cystine-cysteine axis. The findings of the present study implicate that ATG holds great potential to be developed as a novel agent for preventing SLC7A11 inhibition-mediated neurotoxicity.

Gigantol exerts anti-lung cancer activity by inducing ferroptosis via SLC7A11-GPX4 axis.

Gigantol, a naturally occurring dibenzyl compound derived from various orchid species within the Dendrobium genus, exhibits notable pharmacological activity. We found that gigantol has significant anti-lung cancer properties, both in vitro and in vivo, which it exerts through the induction of ferroptosis. Furthermore, we found gigantol's specific interaction with the subunit solute carrier family 7 member 11 (SLC7A11) within the cystine/glutamate antiporter system (system Xc-), leading to the inhibition of glutathione (GSH) synthesis. This, in turn, disrupts redox homeostasis. Additionally, gigantol hinders the uptake of extracellular cystine via lung cancer cells, resulting in reduced cellular levels of cysteine, a vital precursor in GSH synthesis. This reduction, in turn, leads to an increase in the levels of glutamate. Simultaneously, our study reveals that the decrease in GSH significantly inhibits the activity of glutathione peroxidase 4 (GPX4), a key enzyme within the antioxidant system. Remarkably, N-acetylcysteine, a cystine precursor, effectively reverses gigantol-induced ferroptosis in lung cancer cells. This provides further confirmation that the anti-lung cancer mechanism of gigantol is to induce ferroptosis of lung cancer cells by targeting the SLC7A11-GPX4 signaling axis. In conclusion, our study underscores gigantol's potential as a promising candidate drug for the treatment of patients with lung cancer in clinical practice.

SLC7A11-mediated cystine import protects against NDUFS7 deficiency-induced cell death in HEK293T cells.

Cell models of mitochondrial complex Ⅰ (CⅠ) deficiency display significant elevations in reactive oxygen species (ROS) levels and an increase in cellular apoptosis. However, the underlying mechanisms governing anti-apoptotic processes in CⅠ-deficient cells remain elusive. Here, we introduced a mutation in NDUFS7, a crucial subunit of CI, in HEK293T cells and found that the absence of NDUFS7 resulted in reduced cell proliferation, elevated cell death, and increased susceptibility to oxidative stress. Mechanismly, we revealed that the upregulation of SLC7A11 played a crucial role in mitigating cell death resulting from NDUFS7 deficiency. Specifically, the increased expression of SLC7A11 enhanced cystine import, which subsequently reduced cell death by promoting the biosynthesis of reduced glutathione (GSH). Collectively, our findings suggest that SLC7A11-mediated cystine import, representing a novel pathway independent of NADPH production, plays a vital role in protection against NDUFS7 deficiency-induced cell death. This novel pathway provides potential insights into the understanding of pathogenic mechanisms and the therapeutic management of mitochondrial disorders associated with CⅠ deficiency.

HMGA2 regulates GPX4 expression and ferroptosis in prostate cancer cells.

Prostate cancer (PCa) remains a significant global health burden and an increase in oxidative stress is associated with cancer progression. High Mobility Group A2 (HMGA2), a chromatin architectural protein, increases oxidative stress and promotes sensitivity to ferroptosis inducers, however, the mechanism is unknown. We investigated the role of HMGA2 in GPX4 regulation and the impact on cellular responses to oxidative stress and ferroptosis sensitivity. We conducted UALCAN database analysis, western blot analysis, and lipid peroxidation assays to determine the relationship between HMGA2 and GPX4 and the levels of lipid reactive oxygen species in a panel of PCa cell lines, including an enzalutamide-resistant cancer cell line (C4-2B MDVR). Our results show an inverse relationship between HMGA2 and GPX4 expression with high HMGA2 and low GPX4 expression associated with higher Gleason score and lower survival probability in prostate adenocarcinoma (PRAD) patients, while low/moderate HMGA2 expression is positively associated with increased GPX4 expression and higher survival probability. Cell lines showed a moderately negative but not statistically significant correlation between HMGA2 and GPX4 expression, however, PC3 and DU145 PCa cells display higher lipid peroxides concomitant with higher endogenous levels of HMGA2 and low GPX4. Overexpression of wild-type HMGA2 in LNCaP and 22Rv1 cells leads to higher HMGA2 expression compared to Neo control and is associated with higher SLC7A11 and GPX4 expression, while interestingly truncated HMGA2 overexpression in LNCaP and 22Rv1 cells coincides with higher HMGA2 and reduced GPX4 expression, leading to increased lipid peroxides and susceptibility to ferroptosis. Overexpression of wild-type and truncated HMGA2 in 22Rv1 cells increases SLC7A11 mRNA yet differing GPX4 protein expression suggests posttranslational regulation of GPX4. Moreover, enzalutamide-resistant C4-2B MDVR cells display higher HMGA2 levels compared to C4-2B cells, as well as sensitivity to RSL3 ferroptosis inducer, which is partially reversed by ferroptosis inhibitor, ferrostatin-1. Interestingly, GPX4 expression is higher in C4-2B MDVR cells compared to C4-2B, and HMGA2 knockdown further increases its expression but does not significantly alter its susceptibility to ferroptosis. In conclusion, our study shows that HMGA2 regulation of GPX4 expression is complex and truncated HMGA2 downregulates GPX4 and increases lipid peroxides. Moreover, HMGA2-expressing cells including enzalutamide-resistant cells are susceptible to RSL-3-induced ferroptosis. Thus, ferroptosis sensitivity offers promising insights for the development of targeted therapeutic interventions for aggressive PCa.

Implication of system xc- in neuroinflammation during the onset and maintenance of neuropathic pain.

BACKGROUND: Despite the high prevalence of neuropathic pain, treating this neurological disease remains challenging, given the limited efficacy and numerous side effects associated with current therapies. The complexity in patient management is largely attributed to an incomplete understanding of the underlying pathological mechanisms. Central sensitization, that refers to the adaptation of the central nervous system to persistent inflammation and heightened excitatory transmission within pain pathways, stands as a significant contributor to persistent pain. Considering the role of the cystine/glutamate exchanger (also designated as system xc-) in modulating glutamate transmission and in supporting neuroinflammatory responses, we investigated the contribution of this exchanger in the development of neuropathic pain. METHODS: We examined the implication of system xc- by evaluating changes in the expression/activity of this exchanger in the dorsal spinal cord of mice after unilateral partial sciatic nerve ligation. In this surgical model of neuropathic pain, we also examined the consequence of the genetic suppression of system xc- (using mice lacking the system xc- specific subunit xCT) or its pharmacological manipulation (using the pharmacological inhibitor sulfasalazine) on the pain-associated behavioral responses. Finally, we assessed the glial activation and the inflammatory response in the spinal cord by measuring mRNA and protein levels of GFAP and selected M1 and M2 microglial markers. RESULTS: The sciatic nerve lesion was found to upregulate system xc- at the spinal level. The genetic deletion of xCT attenuated both the amplitude and the duration of the pain sensitization after nerve surgery, as evidenced by reduced responses to mechanical and thermal stimuli, and this was accompanied by reduced glial activation. Consistently, pharmacological inhibition of system xc- had an analgesic effect in lesioned mice. CONCLUSION: Together, these observations provide evidence for a role of system xc- in the biochemical processes underlying central sensitization. We propose that the reduced hypersensitivity observed in the transgenic mice lacking xCT or in sulfasalazine-treated mice is mediated by a reduced gliosis in the lumbar spinal cord and/or a shift in microglial M1/M2 polarization towards an anti-inflammatory phenotype in the absence of system xc-. These findings suggest that drugs targeting system xc- could contribute to prevent or reduce neuropathic pain.

GOLPH3 promotes tumor malignancy via inhibition of ferroptosis by upregulating SLC7A11 in cholangiocarcinoma.

Golgi phosphoprotein 3 (GOLPH3) has been reported as an oncogene in various tumors; however, the role and function of GOLPH3 and its relevant molecular mechanism in cholangiocarcinoma (CCA) are unclear. Herein, GOLPH3 expression in CCA tissues was observed to be significantly higher than that in paired adjacent noncancerous tissues. Clinicopathological analysis showed that GOLPH3 expression correlated positively with the tumor-node-metastasis stage. In addition, GOLPH3 expression correlated inversely with the overall survival of patients with CCA. Multivariate analysis showed that GOLPH3 was an independent prognostic factor for patients with CCA. Transcriptome analysis (RNA sequencing) of GOLPH3 knockdown cells showed that the expression levels of nine ferroptosis-related genes were significantly changed, indicating the important biological function of GOLPH3 in ferroptosis in CCA cells. Furthermore, GOLPH3 knockdown could significantly promote Erastin-induced ferroptosis in vitro and suppress tumor growth in vivo. Overexpression of GOLPH3 had the opposite effect on this phenotype. Further studies revealed that GOLPH3 knockdown was significantly associated with a decrease in cysteine content, an accumulation of the lipid peroxidation product malondialdehyde, an increase in reactive oxygen species, and sensitized CCA cells to Erastin-induced ferroptosis. Moreover, changes in GOLPH3 expression were found to be consistent with the expression of light chain subunit solute carrier family 7 member 11 (SLC7A11). Thus, our study suggested that GOLPH3 functions as an oncoprotein in CCA and may suppress ferroptosis by facilitating SLC7A11 expression, suggesting that GOLPH3 could serve as a therapeutic target for CCA treatment.