Temozolomide (TMZ) is an alkylating agent recommended as the first-line pharmaceutical for glioblastoma (GBM), but its efficacy is limited by the development of acquired resistance in GBM cells. TMZ resistance is regulated by multiple factors such as MGMT upregulation and metabolism reprogramming, its underlying mechanism still remains elusive. Peroxisome proliferator-activated receptor alpha (PPARα) is a transcription factor regulating the metabolism of lipid and glucose, while histone 3 lactylation at lysine on position 18 (H3K18la) could promote cancer cells’ resistance to therapeutic drugs. In this study we investigated the role of PPARα in regulating H3K18la and TMZ sensitivity in glioblastoma (GBM) cells. We established TMZ-resistant U87TR, U251TR, and U118TR cells by treating the parental U87, U251, and U118 cells with increased dosages of TMZ until the cells could resist TMZ (200 μM). We found that in TMZ-resistant cells, H3K18la level was apparently upregulated accompanied by increased ECAR (extracellular acidification rate) and intracellular lactate levels, whereas lactate (20 mM) time-dependently upregulated H3K18la in U87 and U251 cells. We found that PPARα was activated by TMZ in U87, U251, and U118 cells, but was inactivated when the cells became resistant to TMZ. In TMZ-sensitive glioma cells, TMZ triggered PPARα activation by causing DNA DSBs-dependent p38 MAPK activation. The activated PPARα upregulated its downstream signal ACOX1, which not only inhibited lactate-mediated H3K18 lactylation by promoting ROS-dependent PKM2 downregulation, but also reversely enhanced PPARα activation through ROS-activated ASK1/p38 MAPK pathway. In GBM cells resistant to TMZ, PPARα and p38 MAPK were both inactivated, but H3K18 lactylation was obviously upregulated. Targeting activation of PPARα with gemfibrozil or GW7647 not only sensitized GBM cells to TMZ but also effectively reversed the acquired resistance of GBM cells to TMZ by suppression of H3K18 lactylation through upregulation of ACOX1. Taken together, PPARα contributed to TMZ-induced growth arrest in GBM cells by inhibiting lactate-mediated H3K18 lactylation, targeting activation of PPARα may be a new strategy to improve the treatment effect of TMZ against GBM.

As a novel lactate-derived post-translational modification, histone lactylation links metabolic reprogramming and epigenetic regulation in cancer. Histone lactylation, particularly at histone H3 lysine 18 lactylation (H3K18la), has been implicated in tumor initiation, progression, metastasis, immune evasion and therapy resistance. It modulates oncogenic pathways (such as PI3K/Akt/mTOR, NF-κB, JAK/STAT) and metabolic pathways (such as glycolysis enhancement, fatty acid synthesis via stearoyl-CoA desaturase and glutamine metabolism) and by altering chromatin structure and gene transcription. In the tumor microenvironment, lactate-induced H3K18la polarizes macrophages toward an M2 phenotype, upregulates immune checkpoints and induces CD8+ T cells dysfunction, which promotes immunosuppression. However, CD8+ T cell-intrinsic lactylation may enhance antitumor immunity during checkpoint blockade. Histone lactylation also induces chemoresistance via autophagy activation, DNA repair and ferroptosis suppression. Therapeutic strategies targeting lactylation include inhibiting lactate transporters, glycolysis or regulation enzymes (such as E1A-binding protein, lysine acetyltransferase 2A and brahma-related gene 1). Furthermore, the clinical potential is emerging, with H3K18la and H4K5la serving as prognostic biomarkers in multiple types of cancer. However, key questions regarding the non-enzymatic modification mechanisms, identification of histone lactation regulatory enzymes and pan-cancer functional heterogeneity are yet to be elucidated. Future research should prioritize translational validation of lactylation-targeted therapies and their integration with existing regimens to overcome resistance and improve immunotherapy efficacy.

Ferroptosis is a type of programmed cell death resulting from iron overload-dependent lipid peroxidation, and could be promoted by activating transcription factor 3 (ATF3). SIRT1 is an enzyme accounting for removing acetylated lysine residues from target proteins by consuming NAD+, but its role remains elusive in ferroptosis and activating ATF3. In this study, we found SIRT1 was activated during the process of RSL3-induced glioma cell ferroptosis. Moreover, the glioma cell death was aggravated by SIRT1 activator SRT2183, but suppressed by SIRT inhibitor EX527 or when SIRT1 was silenced with siRNA. These indicated SIRT1 sensitized glioma cells to ferroptosis. Furthermore, we found SIRT1 promoted RSL3-induced expressional upregulation and nuclear translocation of ATF3. Silence of ATF3 with siRNA attenuated RSL3-induced increases of ferrous iron and lipid peroxidation, downregulation of SLC7A11 and GPX4 and depletion of cysteine and GSH. Thus, SIRT1 promoted glioma cell ferroptosis by inducting ATF3 activation. Mechanistically, ATF3 activation was reinforced when RSL3-induced decline of NAD+ was aggravated by FK866 that could inhibit NAD + synthesis via salvage pathway, but suppressed when intracellular NAD+ was maintained at higher level by supplement of exogenous NAD+. Notably, the NAD + decline caused by RSL3 was enhanced when SIRT1 was further activated by SRT2183, but attenuated when SIRT1 activation was inhibited by EX527. These indicated SIRT1 promoted ATF3 activation via consumption of NAD+. Finally, we found RSL3 activated SIRT1 by inducing reactive oxygen species-dependent upregulation of AROS. Together, our study revealed SIRT1 activated by AROS sensitizes glioma cells to ferroptosis via activation of ATF3-dependent inhibition of SLC7A11 and GPX4.

BACKGROUND:Copper is an essential trace element for biological systems, as it plays a critical role in the activity of various enzymes and metabolic processes. However, the dysregulation of copper homeostasis is closely associated with the onset and progression of numerous diseases. In recent years, copper-induced cell death, a novel form of cellular demise, has garnered significant attention. This process is characterized by the abnormal accumulation of intracellular copper ions, leading to cellular dysfunction and eventual cell death. Copper toxicity occurs through the interaction of copper with acylated enzymes in the tricarboxylic acid (TCA) cycle. This interaction results in subsequent protein aggregation, causing proteotoxic stress and ultimately resulting in cell death. Despite the promise of these findings, the detailed mechanisms and broader implications of cuproptosis remain underexplored. Therefore, our study aimed to investigate the role of copper in cell death and autophagy, focusing on the molecular mechanisms of cuproptosis. We also aimed to discuss recent advancements in copper-related research across various diseases and tumors, providing insights for future studies and potential therapeutic applications. MAIN BODY:This review delves into the biological significance of copper metabolism and the molecular mechanisms underlying copper-induced cell death. Furthermore, we discuss the role of copper toxicity in the pathogenesis of various diseases, emphasizing recent advancements in the field of oncology. Additionally, we explore the therapeutic potential of targeting copper toxicity. CONCLUSION:The study highlights the need for further research to explore alternative pathways of copper-induced cell death, detailed mechanisms of cuproptosis, and biomarkers for copper poisoning. Future research should focus on exploring the molecular mechanisms of cuproptosis, developing new therapeutic strategies, and verifying their safety and efficacy in clinical trials.

Parthanatos is a type of programmed cell death dependent on hyper-activation of poly (ADP-ribose) polymerase 1 (PARP-1). SIRT1 is a highly conserved nuclear deacetylase and often acts as an inhibitor of parthanatos by deacetylation of PARP1. Our previous study showed that deoxypodophyllotoxin (DPT), a natural compound isolated from the traditional herb Anthriscus sylvestris, triggered glioma cell death via parthanatos. In this study, we investigated the role of SIRT1 in DPT-induced human glioma cell parthanatos. We showed that DPT (450 nmol/L) activated both PARP1 and SIRT1, and induced parthanatos in U87 and U251 glioma cells. Activation of SIRT1 with SRT2183 (10 μmol/L) enhanced, while inhibition of SIRT1 with EX527 (200 μmol/L) or knockdown of SIRT1 attenuated DPT-induced PARP1 activation and glioma cell death. We demonstrated that DPT (450 nmol/L) significantly decreased intracellular NAD+ levels in U87 and U251 cells. Further decrease of NAD+ levels with FK866 (100 μmol/L) aggravated, but supplement of NAD+ (0.5, 2 mmol/L) attenuated DPT-induced PARP1 activation. We found that NAD+ depletion enhanced PARP1 activation via two ways: one was aggravating ROS-dependent DNA DSBs by upregulation of NADPH oxidase 2 (NOX2); the other was reinforcing PARP1 acetylation via increase of N-acetyltransferase 10 (NAT10) expression. We found that SIRT1 activity was improved when being phosphorylated by JNK at Ser27, the activated SIRT1 in reverse aggravated JNK activation via upregulating ROS-related ASK1 signaling, thus forming a positive feedback between JNK and SIRT1. Taken together, SIRT1 activated by JNK contributed to DPT-induced human glioma cell parthanatos via initiation of NAD+ depletion-dependent upregulation of NOX2 and NAT10.

Parthanatos is a type of programmed cell death initiated by over-activated poly (ADP-ribose) polymerase 1 (PARP1). Nuclear translocation of apoptosis inducing factor (AIF) is a prominent feature of parthanatos. But it remains unclear how activated nuclear PARP1 induces mitochondrial AIF translocation into nuclei. Evidence has shown that deoxypodophyllotoxin (DPT) induces parthanatos in glioma cells via induction of excessive ROS. In this study we explored the downstream signal of activated PARP1 to induce nuclear translocation of AIF in DPT-triggered glioma cell parthanatos. We showed that treatment with DPT (450 nM) induced PARP1 over-activation and Tax1 binding protein 1 (TAX1BP1) distribution to mitochondria in human U87, U251 and U118 glioma cells. PARP1 activation promoted TAX1BP1 distribution to mitochondria by depleting nicotinamide adenine dinucleotide (NAD+). Knockdown of TAX1BP1 with siRNA not only inhibited TAX1BP1 accumulation in mitochondria, but also alleviated nuclear translocation of AIF and glioma cell death. We demonstrated that TAX1BP1 enhanced the activity of respiratory chain complex I not only by upregulating the expression of ND1, ND2, NDUFS2 and NDUFS4, but also promoting their assemblies into complex I. The activated respiratory complex I generated more superoxide to cause mitochondrial depolarization and nuclear translocation of AIF, while the increased mitochondrial superoxide reversely reinforced PARP1 activation by inducing ROS-dependent DNA double strand breaks. In mice bearing human U87 tumor xenograft, administration of DPT (10 mg· kg−1 ·d−1, i.p., for 8 days) markedly inhibited the tumor growth accompanied by NAD+ depletion, TAX1BP1 distribution to mitochondria, AIF distribution to nuclei as well as DNA DSBs and PARP1 activation in tumor tissues. Taken together, these data suggest that TAX1BP1 acts as a downstream signal of activated PARP1 to trigger nuclear translocation of AIF by activation of mitochondrial respiratory chain complex I.

BNIP3 is found to eliminate cancer cells via causing mitochondrial damage and endoplasmic reticulum stress, but it remains elusive of its role in regulating DNA double strand breaks (DSBs). In this study, we find that silibinin triggers DNA DSBs, ROS accumulation and expressional upregulation of BNIP3 in glioma cells. Mitigation of ROS with antioxidant GSH significantly inhibits silibinin-induced DNA DSBs and glioma cell death. Then, we find knockdown of BNIP3 with SiRNA obviously prevents silibinin-induced DNA DSBs and ROS accumulation. Mechanistically, BNIP3 knockdown not only reverses silibinin-triggered depletion of cysteine and GSH via maintaining xCT level, but also abrogates catalase decrease. Notably, silibinin-induced dephosphorylation of mTOR is also prevented when BNIP3 is knocked down. Given that activated mTOR could promote xCT expression and inhibit autophagic degradation of catalase, our data suggest that BNIP3 contributes to silibinin-induced DNA DSBs via improving intracellular ROS by inhibition of mTOR.

1病例资料 66岁男性,因头晕20 d、头痛10d入院.入院体格检查:四肢肌力Ⅴ级,肌张力正常,病理反射未引出.头部MRI平扫+增强见右侧顶叶2.74 cm×2.05 cm×1.99 cm异常信号,边界欠清晰,T1WI呈稍低及低信号,T2WI为高及稍高信号,Dark-fluid为稍高及稍低信号,增强后呈厚薄不均环形强化,病变周边见大面积水肿(图1A、1B).术前考虑右顶叶胶质瘤可能性大,不除外转移瘤.遂行右侧顶叶病变切除术.术中切开顶叶皮层下1 cm即可见肿瘤,无包膜,切面灰白,供血较丰富,局部见坏死,局部呈胶冻样.术后头晕及头痛症状明显好转.术后病理为右侧顶叶胶质肉瘤(图1E、1F).术后2个月复查MRI未见肿瘤复发(图1C、1D).

Ferroptosis triggered by hemin is regarded as a primary factor accounting for neuronal death secondary to intracerebral hemorrhage. Thus, compounds with inhibitory effect on hemin-induced ferroptosis might be potential medicines to prevent neuronal death caused by intracerebral hemorrhage. Herein, we investigate whether maltol could alleviate hemin-induced SH-SY5Y cell ferroptosis and its potential mechanisms. It is found that maltol effectively prevents hemin-induced SH-SY5Y cell ferroptosis via three pathways. The first one is inhibiting intracellular iron increase via preventing upregulation of transferrin receptor, the second one is alleviating lipid peroxidation via attenuating H2O2 generation by NOX4 and promoting H2O2 clearance by catalase, and the third one is to reduce peroxidized lipids via maintaining GPX4/GSH pathway. Therefore, maltol is a novel agent preventing hemin-induced SH-SY5Y cell ferroptosis.

FOXO3a (forkhead box transcription factor 3a) is involved in regulating multiple biological processes in cancer cells. BNIP3 (Bcl-2/adenovirus E1B 19-kDa-interacting protein 3) is a receptor accounting for priming damaged mitochondria for autophagic removal. In this study we investigated the role of FOXO3a in regulating the sensitivity of glioma cells to temozolomide (TMZ) and its relationship with BNIP3-mediated mitophagy. We showed that TMZ dosage-dependently inhibited the viability of human U87, U251, T98G, LN18 and rat C6 glioma cells with IC 50 values of 135.75, 128.26, 142.65, 155.73 and 111.60 μM, respectively. In U87 and U251 cells, TMZ (200 μM) induced DNA double strand breaks (DSBs) and nuclear translocation of apoptosis inducing factor (AIF), which was accompanied by BNIP3-mediated mitophagy and FOXO3a accumulation in nucleus. TMZ treatment induced intracellular ROS accumulation in U87 and U251 cells via enhancing mitochondrial superoxide, which not only contributed to DNA DSBs and exacerbated mitochondrial dysfunction, but also upregulated FOXO3a expression. Knockdown of FOXO3a aggravated TMZ-induced DNA DSBs and mitochondrial damage, as well as glioma cell death. TMZ treatment not only upregulated BNIP3 and activated autophagy, but also triggered mitophagy by prompting BNIP3 translocation to mitochondria and reinforcing BNIP3 interaction with LC3BII. Inhibition of mitophagy by knocking down BNIP3 with SiRNA or blocking autophagy with 3MA or bafilomycin A1 exacerbated mitochondrial superoxide and intracellular ROS accumulation. Moreover, FOXO3a knockdown inhibited TMZ-induced BNIP3 upregulation and autophagy activation. In addition, we showed that treatment with TMZ (100 mg·kg −1 ·d −1 , ip) for 12 days in C6 cell xenograft mice markedly inhibited tumor growth accompanied by inducing FOXO3a upregulation, oxidative stress and BNIP3-mediated mitophagy in tumor tissues. These results demonstrate that FOXO3a attenuates temozolomide-induced DNA double strand breaks in human glioma cells via promoting BNIP3-mediated mitophagy.

Ferroptotic cell death is characterized by iron-dependent lipid peroxidation that is initiated by ferrous iron and H 2 O 2 via Fenton reaction, in which the role of activating transcription factor 3 (ATF3) remains elusive. Brucine is a weak alkaline indole alkaloid extracted from the seeds of Strychnos nux-vomica , which has shown potent antitumor activity against various tumors, including glioma. In this study, we showed that brucine inhibited glioma cell growth in vitro and in vivo, which was paralleled by nuclear translocation of ATF3, lipid peroxidation, and increases of iron and H 2 O 2 . Furthermore, brucine-induced lipid peroxidation was inhibited or exacerbated when intracellular iron was chelated by deferoxamine (500 μM) or improved by ferric ammonium citrate (500 μM). Suppression of lipid peroxidation with lipophilic antioxidants ferrostatin-1 (50 μM) or liproxstatin-1 (30 μM) rescued brucine-induced glioma cell death. Moreover, knockdown of ATF3 prevented brucine-induced accumulation of iron and H 2 O 2 and glioma cell death. We revealed that brucine induced ATF3 upregulation and translocation into nuclei via activation of ER stress. ATF3 promoted brucine-induced H 2 O 2 accumulation via upregulating NOX4 and SOD1 to generate H 2 O 2 on one hand, and downregulating catalase and xCT to prevent H 2 O 2 degradation on the other hand. H 2 O 2 then contributed to brucine-triggered iron increase and transferrin receptor upregulation, as well as lipid peroxidation. This was further verified by treating glioma cells with exogenous H 2 O 2 alone. Moreover, H 2 O 2 reversely exacerbated brucine-induced ER stress. Taken together, ATF3 contributes to brucine-induced glioma cell ferroptosis via increasing H 2 O 2 and iron.