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Recent studies on enzymes and reader proteins for histone crotonylation support a function of histone crotonyla- tion in transcription. However, the enzyme（s） responsible for histone decrotonylation （HDCR） remains poorly de- fined. Moreover, it remains to be determined if histone crotonylation is physiologically significant and functionally distinct from or redundant to histone acetylation. Here we present evidence that class I histone deacetylases （HDACs） rather than sirtuin family deacetylases （SIRTs） are the major histone decrotonylases, and that histone erotonylation is as dynamic as bistone acetylation in mammalian cells. Notably, we have generated novel HDAC1 and HDAC3 mutants with impaired HDAC but intact HDCR activity. Using these mutants we demonstrate that selective HDCR in mammalian cells correlates with a broad transcriptional repression and diminished promoter association of cro- tonylation but not acetylation reader proteins. Furthermore, we show that histone erotonylation is enriched in and required for self-renewal of mouse embryonic stem cells.

Ferroptosis, a form of regulated cell death caused by lipid peroxidation, was recently identified as a natural tumor suppression mechanism. Here, we show that ionizing radiation (IR) induces ferroptosis in cancer cells. Mechanistically, IR induces not only reactive oxygen species (ROS) but also the expression of ACSL4, a lipid metabolism enzyme required for ferroptosis, resulting in elevated lipid peroxidation and ferroptosis. ACSL4 ablation largely abolishes IR-induced ferroptosis and promotes radioresistance. IR also induces the expression of ferroptosis inhibitors, including SLC7A11 and GPX4, as an adaptive response. IR- or KEAP1 deficiency-induced SLC7A11 expression promotes radioresistance through inhibiting ferroptosis. Inactivating SLC7A11 or GPX4 with ferroptosis inducers (FINs) sensitizes radioresistant cancer cells and xenograft tumors to IR. Furthermore, radiotherapy induces ferroptosis in cancer patients, and increased ferroptosis correlates with better response and longer survival to radiotherapy in cancer patients. Our study reveals a previously unrecognized link between IR and ferroptosis and indicates that further exploration of the combination of radiotherapy and FINs in cancer treatment is warranted.

Targeting ferroptosis, a unique cell death modality triggered by unrestricted lipid peroxidation, in cancer therapy is hindered by our incomplete understanding of ferroptosis mechanisms under specific cancer genetic contexts. KEAP1 (kelch-like ECH associated protein 1) is frequently mutated or inactivated in lung cancers, and KEAP1 mutant lung cancers are refractory to most therapies, including radiotherapy. In this study, we identify ferroptosis suppressor protein 1 (FSP1, also known as AIFM2) as a transcriptional target of nuclear factor erythroid 2-related factor 2 (NRF2) and reveal that the ubiquinone (CoQ)-FSP1 axis mediates ferroptosis- and radiation- resistance in KEAP1 deficient lung cancer cells. We further show that pharmacological inhibition of the CoQ-FSP1 axis sensitizes KEAP1 deficient lung cancer cells or patient-derived xenograft tumors to radiation through inducing ferroptosis. Together, our study identifies CoQ-FSP1 as a key downstream effector of KEAP1-NRF2 pathway and as a potential therapeutic target for treating KEAP1 mutant lung cancers. KEAP1 mutations are frequently observed in NSCLC and lead to drug resistance. Here, the authors show that KEAP1 mutations in lung cancer cells leads to FSP1 upregulation through NRF2, resulting in ferroptosis resistance and radioresistance.

The cystine transporter solute carrier family 7 member 11 (SLC7A11; also called xCT) protects cancer cells from oxidative stress and is overexpressed in many cancers. Here we report a surprising finding that, whereas moderate overexpression of SLC7A11 is beneficial for cancer cells treated with H 2 O 2 , a common oxidative stress inducer, its high overexpression dramatically increases H 2 O 2 -induced cell death. Mechanistically, high cystine uptake in cancer cells with high overexpression of SLC7A11 in combination with H 2 O 2 treatment results in toxic buildup of intracellular cystine and other disulfide molecules, NADPH depletion, redox system collapse, and rapid cell death (likely disulfidptosis). We further show that high overexpression of SLC7A11 promotes tumor growth but suppresses tumor metastasis, likely because metastasizing cancer cells with high expression of SLC7A11 are particularly susceptible to oxidative stress. Our findings reveal that SLC7A11 expression level dictates cancer cells’ sensitivity to oxidative stress and suggests a context-dependent role for SLC7A11 in tumor biology. The cystine transporter SLC7A11 protects cancer cells from oxidative stress by supporting glutathione synthesis. Here, the authors show that the expression level of SLC7A11 leads to different outcomes depending on context, so high expression promotes primary tumour growth but promotes disulfide stress under oxidative stress conditions and impairs metastasis.

Glutathione peroxidase 4 (GPX4) utilizes glutathione (GSH) to detoxify lipid peroxidation and plays an essential role in inhibiting ferroptosis. As a selenoprotein, GPX4 protein synthesis is highly inefficient and energetically costly. How cells coordinate GPX4 synthesis with nutrient availability remains unclear. In this study, we perform integrated proteomic and functional analyses to reveal that SLC7A11-mediated cystine uptake promotes not only GSH synthesis, but also GPX4 protein synthesis. Mechanistically, we find that cyst(e)ine activates mechanistic/mammalian target of rapamycin complex 1 (mTORC1) and promotes GPX4 protein synthesis at least partly through the Rag-mTORC1-4EBP signaling axis. We show that pharmacologic inhibition of mTORC1 decreases GPX4 protein levels, sensitizes cancer cells to ferroptosis, and synergizes with ferroptosis inducers to suppress patient-derived xenograft tumor growth in vivo. Together, our results reveal a regulatory mechanism to coordinate GPX4 protein synthesis with cyst(e)ine availability and suggest using combinatorial therapy of mTORC1 inhibitors and ferroptosis inducers in cancer treatment. Glutathione peroxidase 4 (GPX4) inhibits ferroptosis, but protein synthesis is inefficient and costly. Here, the authors reveal that cystine uptake promotes GPX4 synthesis by activating mTORC1 and show that cancer cells are sensitized to ferroptosis by mTORC1 inhibition.

SLC7A11-mediated cystine uptake is critical for maintaining redox balance and cell survival. Here we show that this comes at a significant cost for cancer cells with high levels of SLC7A11. Actively importing cystine is potentially toxic due to its low solubility, forcing cancer cells with high levels of SLC7A11 (SLC7A11high) to constitutively reduce cystine to the more soluble cysteine. This presents a significant drain on the cellular NADPH pool and renders such cells dependent on the pentose phosphate pathway. Limiting glucose supply to SLC7A11high cancer cells results in marked accumulation of intracellular cystine, redox system collapse and rapid cell death, which can be rescued by treatments that prevent disulfide accumulation. We further show that inhibitors of glucose transporters selectively kill SLC7A11high cancer cells and suppress SLC7A11high tumour growth. Our results identify a coupling between SLC7A11-associated cystine metabolism and the pentose phosphate pathway, and uncover an accompanying metabolic vulnerability for therapeutic targeting in SLC7A11high cancers.Liu et al. show that cancer cells with high levels of SLC7A11 have increased dependency on the pentose phosphate pathway and consequently accumulate disulfide, and can be therapeutically targeted by limiting glucose supply.

The chromosome 8q24.21 locus, which contains the proto-oncogene c- MYC , long non-coding RNA PVT1 , and microRNAs (miRs), is the most commonly amplified region in human prostate cancer. A long-range interaction of genetic variants with c- MYC or long non-coding PVT1 at this locus contributes to the genetic risk of prostate cancer. At this locus is a cluster of genes for six miRs (miR-1204, -1205, -1206, -1207-3p, -1207-5p, and -1208), but their functional role remains elusive. Here the copy numbers and expression levels of miRs-1204–1208 were investigated using quantitative PCR for prostate cancer cell lines and primary tumors. The data revealed that copy numbers and expression of miR-1205 were increased in both castration-resistant prostate cancer cell lines and in primary tumors. In castration-resistant prostate cancer specimens, the copy number at the miR-1205 locus correlated with the expression of miR-1205. Furthermore, functional analysis with an miR-1205 mimic, an miR-1205 inhibitor, and CRISPR/Cas9 knockout revealed that, in human prostate cancer cells, miR-1205 promoted cell proliferation and cell cycle progression and inhibited hydrogen peroxide-induced apoptosis. In these cells, miR-1205 downregulated the expression of the Egl-9 family hypoxia inducible factor 3 ( EGLN3 ) gene and targeted a site in its 3′-untranslated region to downregulate its transcriptional activity. Thus, by targeting EGLN3 , miR-1205 has an oncogenic role and may contribute to the genetic risk of castration-resistant prostate cancer.

The growing knowledge of ferroptosis has suggested the role and therapeutic potential of ferroptosis in cancer, but has not been translated into effective therapy. Liver cancer, primarily hepatocellular carcinoma (HCC), is highly lethal with limited treatment options. LIFR is frequently downregulated in HCC. Here, by studying hepatocyte-specific and inducible Lifr-knockout mice, we show that loss of Lifr promotes liver tumorigenesis and confers resistance to drug-induced ferroptosis. Mechanistically, loss of LIFR activates NF-κB signaling through SHP1, leading to upregulation of the iron-sequestering cytokine LCN2, which depletes iron and renders insensitivity to ferroptosis inducers. Notably, an LCN2-neutralizing antibody enhances the ferroptosis-inducing and anticancer effects of sorafenib on HCC patient-derived xenograft tumors with low LIFR expression and high LCN2 expression. Thus, anti-LCN2 therapy is a promising way to improve liver cancer treatment by targeting ferroptosis. Leukemia inhibitory factor receptor (LIFR) is frequently downregulated in liver cancer. Here the authors show that loss of LIFR promotes liver tumorigenesis and confers resistance to drug-induced ferroptosis through NF-κB-mediated upregulation of iron-sequestering cytokine LCN2.

Cisplatin is a widely used chemotherapy drug for the treatment of various cancers; however, its clinical use is often accompanied by skeletal muscle atrophy, which not only impacts patients’ physical health but also significantly diminishes their quality of life. The mechanisms underlying cisplatin-induced muscle atrophy are complex and involve a series of molecular biological processes, including oxidative stress, inflammation, protein degradation, and muscle cell apoptosis. Recent studies have suggested that exercise intervention can significantly alleviate cisplatin-induced muscle damage by modulating exercise-induced myokines. Myokines, such as muscle-derived cytokines (e.g., IL-6, irisin) and other related factors, can mitigate muscle atrophy through anti-inflammatory, antioxidative, and muscle-synthesis-promoting mechanisms. This review explores the molecular mechanisms of cisplatin-induced skeletal muscle atrophy, examines the potential protective effects of exercise intervention, and highlights the role of exercise-induced myokines in this process. The findings suggest that exercise not only alleviates chemotherapy-induced muscle atrophy by improving metabolic and immune status but also activates myokines to promote muscle regeneration and repair, offering a promising adjunctive therapy for cisplatin-treated patients.