Cell Death & Disease最新文献

Small molecule inhibitors designed to specifically target oncogenic proteins have demonstrated potent anti-tumour activities due to direct effects on tumour cells survival and/or proliferation. However, the effects of these compounds on normal cells, specifically immune cells and their potential to impede or enhance anti-cancer immunotherapies has yet to be fully explored. Using an in vitro co-culture system to assess CD8+ T cell killing of tumour cells, we identified compounds that inhibit Bcl-2 and Bcl-xl as agents that can induce tumour cell death without impacting the differentiation or function of anti-tumour T cells. Accordingly, in vivo treatment of mice bearing solid tumours with a combination of the Bcl-2/Bcl-xl inhibitor AZD0466 and anti-PD-L1 immunotherapy resulted in enhanced anti-tumour effects and improved survival compared to equivalent monotherapies.

Colorectal cancer (CRC) is the third most common malignant tumor and the second leading cause of cancer-related mortality globally. Epithelial to mesenchymal transition (EMT) contributes to CRC metastasis and poor prognosis. Aberrant protein phosphorylation is implicated in CRC progression, warranting further investigation into its molecular mechanisms. Herein, we have identified significant alterations in protein phosphorylation associated with CRC through tandem mass tag (TMT) label-based phosphoproteomic analysis. The functions and enriched signaling pathways of these proteins were predominantly linked to the EMT process. Notably, the phosphorylation of eIF4B at Ser93 exhibited the most pronounced increase in CRC, a finding that was further validated in CRC tissues and cell lines by a newly generated antibody targeting eIF4B Ser93 phosphorylation. Phosphorylation of eIF4B Ser93 promoted CRC progression and metastasis both in vitro and in vivo. Mechanistically, eIF4B Ser93 phosphorylation decreased ubiquitination-mediated eIF4B degradation and enhanced its translation activity, through which it facilitated the translation of mesenchymal markers. Additionally, ERK2 directly phosphorylated eIF4B at Ser93, while inhibiting this phosphorylation is essential for the anti-cancer efficacy of the ERK2 inhibitor, Vx-11e. Together, the phosphorylation of eIF4B Ser93 driven by ERK2 promotes CRC growth and metastasis through the activation of EMT. Our findings indicate a novel therapeutic target and provide promising strategies for clinical intervention in human CRC.

T cell recovery is critical following damage, such as hematopoietic cell transplantation (HCT), with increased reconstitution associated with improved clinical outcomes. Endogenous thymic regeneration, a crucial process for restoring immune competence following cytoreductive therapies such as HCT conditioning, is often delayed, limiting T cell reconstitution. Fully understanding the molecular mechanisms driving regeneration is therefore crucial for uncovering therapeutic targets that can be exploited to enhance thymic function. Here, we identified that CD4+ CD8+ thymocytes rapidly and acutely undergo lytic cell death, specifically pyroptosis, following acute damage caused by ionizing radiation, and release damage-associated molecular patterns (DAMPS) into the thymic microenvironment, including ATP. Extracellular ATP stimulates the P2Y2 purinergic receptor on thymic epithelial cells (TECs)-a stromal cell crucial for supporting T cell development-resulting in the upregulation FOXN1, the master TEC transcription factor. Targeting the P2Y2 receptor with a P2Y2 agonist, UTPγS, promotes rapid regeneration of the TEC compartment in vivo following acute damage. These findings reveal a novel damage-sensing mechanism employed by the thymus where thymocytes adopt an alternative cell death mechanism which promotes thymic repair via P2Y2 signaling in TECs. This work identifies P2Y2 as a promising therapeutic target for enhancing thymus regeneration and improving immune recovery after HCT.

Hepatocellular carcinoma (HCC) is a major global health burden. Despite recent advances in immunotherapy, tyrosine kinase inhibitors (TKIs) treatment or combined therapies, therapeutic resistance and disease progression remain significant challenges. SOX4, a transcription factor frequently overexpressed in HCC and other cancers, has been linked to drug resistance and poor prognosis; however, the underlying molecular mechanisms remain unexplored. In this study, we identify STAT6 as a novel transcriptional target and interacting partner of SOX4 in HCC cells. Genetic ablation or knockdown of SOX4 induced hypermethylation of the STAT6 promoter, suppressing its expression, while treatment with the DNA methyltransferase inhibitor 5-Aza-2'-deoxycytidine restored STAT6 levels, indicating an epigenetic mechanism of regulation. In addition, SOX4 is physically associated with STAT6, as confirmed by co-immunoprecipitation and immunofluorescence. SOX4 depletion impaired interleukin-4 (IL-4)-induced phosphorylation of STAT6 at tyrosine residue 641 (Y641), implicating SOX4 in IL-4-mediated STAT6 activation. Chromatin immunoprecipitation (ChIP) assays demonstrated that SOX4 and STAT6 co-occupy the promoter of MTHFD2, a key enzyme in folate metabolism, regulating NADH/NADPH production and nucleotide biosynthesis. Knockdown of SOX4 or STAT6, or mutation of their binding sites within the MTHFD2 promoter, reduced MTHFD2 expression, NADPH levels, and nucleotide synthesis. Transcriptomic analyses from TCGA-LIHC and our independent cohort revealed a strong positive correlation between SOX4, STAT6, and MTHFD2, with MTHFD2 overexpression linked to poor overall survival. Clinically, elevated SOX4/STAT6/MTHFD2 axis activity was associated with resistance to immunotherapy or TKIs, either in our enrolled cohort or transcriptome data obtained from GSE109211. Metabolomic profiling further revealed increased NADPH and nucleotide biosynthesis in tumors with high SOX4/STAT6/MTHFD2 expression. Targeting STAT6 or MTHFD2 suppressed tumor growth in TKIs-resistant patient-derived xenograft models. Collectively, our findings identify the SOX4-STAT6-MTHFD2 axis as a critical driver of HCC progression and therapeutic resistance, offering a promising target for intervention in refractory HCC.

Mitochondrial metabolism plays a crucial role in cancer progression and is associated with effective channeling of electrons through Complex I. The ability to adapt this electron flow as per cellular demands is critical for energy homeostasis. Our observations suggest that proliferating cells regulate the electron entry point through alterations in the levels of Methylation-Controlled J-protein (MCJ). Elevated MCJ levels were found to promote aggressive proliferative and migratory phenotypes, leading to increased primary tumor burden. The phenotype was attributed to MCJ-mediated regulation of mitochondrial bioenergetic plasticity, enabling a preferential rerouting of electron flux through succinate dehydrogenase complex (Complex II). Consequently, cells exhibited suppressed glycolysis and a metabolic shift toward lipid-fueled mitochondrial respiration, marked by increased lipid accumulation and its oxidation. Despite Complex I uncoupling, these cells maintained better respiratory output and preserved NADH levels to support an increased redox potential. These findings decouple the reliance on Complex I for effective mitochondrial respiration and underscore the significance of Complex II-driven metabolism in tumor growth, an important consideration for development of future therapeutics, particularly when current strategies predominantly target Complex I-dependent respiration.

Primary and secondary bile acid (BA) levels are elevated in patients with hepatocellular carcinoma (HCC). BAs are important signaling molecules that regulate CYP8B1 expression by targeting nuclear and membrane receptors. In this study, we aimed to determine the function of CYP8B1 in HCC. Examination of HCC tissue and bioinformatic analysis revealed that CYP8B1 expression is downregulated in HCC tissues and is associated with good prognosis. Cholic acid promoted Huh7 cell proliferation and migration by inhibiting CYP8B1 expression. Both in vitro and in vivo, CYP8B1 inhibited the proliferation, invasion, and migration of HCC cells. Nanopore long-read RNA-sequencing analysis identified PAK4 as a potential target of CYP8B1, and the MAPK pathway was associated with CYP8B1 expression. CYP8B1 inhibited PAK4 expression and Raf/MEK/ERK phosphorylation. Tissue microarray analysis also verified a strong correlation between CYP8B1 and PAK4 expression. In vitro Cell Counting Kit 8 assays and in vivo orthotopic liver tumor model analyses showed that CYP8B1 restores sorafenib sensitivity in resistant HC, suggesting its potential as a therapeutic target. IP-MS of CYP8B1 and transcription factor prediction of PAK4 revealed STAT1 as a potential transcription factor for PAK4, which may directly bind to CYP8B1. Chromatin immunoprecipitation confirmed that u-STAT1 directly binds to the PAK4 promoter, not p-STAT1. Overall, CYP8B1 binds to u-STAT1 in the cytoplasm, reducing the translocation of u-STAT1 from the cytoplasm to the nucleus, thereby inhibiting the transcription of PAK4 and ultimately inhibiting the phosphorylation of Raf/MEK/ERK. Our findings indicate that the CYP8B1/PAK4 axis is important in HCC progression and elucidate the mechanism by which BAs promote HCC. Thus, CYP8B1 is a potential therapeutic target for the clinical treatment of HCC.

The epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells is one of the significant pathogenic mechanisms for the formation of subretinal fibrosis in age-related macular degeneration (AMD). Multiple signaling pathways that promote EMT have been well described, yet the endogenous signaling pathways that inhibit EMT within RPE cells remain largely elusive. In this study, we confirmed the expression of CRX in human RPE cells and human embryonic stem cell-derived RPE (ESC-RPE) cells. By employing sub-culture to disrupt intercellular connections and thereby inhibit the Hippo signaling pathway, combined with TGF-β1 treatment in vitro to mimic the microenvironment for the formation of subretinal fibrosis, it was revealed that Hippo/YAP1 and TGF-β1 synergistically promoted the nuclear translocation of β-catenin, and the latter bound to TCF7 to inhibit the expression of CRX. Overexpression of CRX was capable of suppressing the occurrence of EMT in ESC-RPE cells. CRX exerted its inhibitory effect on EMT partly by upregulating the expression of PPP2R2B. In the laser-induced choroidal neovascularization mouse model, the nuclear translocation of CRX took place in RPE cells, and overexpression of CRX played an inhibitory role in the formation of subretinal fibrosis. This study has identified CRX as an endogenous signaling molecule that inhibits EMT in RPE cells and has provided a new research target and treatment strategy for the treatment of wet AMD and the inhibition of subretinal fibrosis formation.

Cisplatin administration is the primary chemotherapy approach for many epithelial cancers. However, resistance to this drug poses a significant challenge to effective treatment. Despite the identification of numerous factors associated with resistance, reliable biomarkers predicting drug response remain elusive. Previously, low expression of the NPRL2 tumor suppressor was linked to cisplatin resistance. NPRL2, along with NPRL3 and DEPDC5, forms the GATOR1 complex, an upstream regulator of the mTORС1, the function of which is perturbed in many cancers, particularly those resistant to cisplatin. Here, we compare non-cancerous bronchial epithelium BEAS-2B cells with GATOR1 deletions, serving as a model of intrinsic cisplatin resistance, with non-small cell lung cancer lines A549, H460, and H1975 with acquired resistance to the drug. We found that deletion of any GATOR1 member, not solely NPRL2, promotes cisplatin resistance, whereas their overexpression renders cells sensitive to the drug. In cells with GATOR1 deletions, expression of the ATP7A transporter required for cisplatin efflux is increased, while expression of cisplatin influx transporters CTR2 and LRRC8A is downregulated, especially after treatment with the drug. This hinders drug accumulation in cells, resulting in the formation of fewer cisplatin-DNA adducts. Simultaneously, these cells exhibit enhanced DNA damage response and mTORC1 activity. Overexpression of GATOR1 components and/or concomitant treatment with an mTORC1 inhibitor restores sensitivity to cisplatin. Transcriptomic analysis of GATOR1-deleted BEAS-2B cells, treated or not with the drug, identifies new signatures important for understanding GATOR1 function and its role in cisplatin resistance. Thus, GATOR1 not only participates in the cellular response to amino acid availability but also plays a role in resistance to DNA-damaging anticancer drugs. This novel function of GATOR1 should be taken into account when developing new strategies to combat chemoresistance.

Aging is a progressive process characterized by cellular and molecular damage leading to mitochondrial dysfunction and cognitive decline. Mitochondrial dysfunction is a critical factor in memory impairment in aging and neurodegenerative diseases. While sex differences in aging have been observed across various species, the underlying cellular and molecular mechanisms remain poorly understood, mainly focused on mitochondrial proteostasis. This study examined hippocampal-dependent cognitive decline and mitochondrial dysfunction in aged male and female C57BL/6 J mice. Our results reveal sex-dependent differences in cognitive impairment, with aged males exhibiting more significant deficits in spatial and localization memory, while aged females show impairments in recognition memory. Additionally, aged males display increased oxidative stress and exacerbated mitochondrial superoxide production, leading to more severe bioenergetic deficiencies. Conversely, aged females exhibit heightened mitochondrial permeability transition pore (mPTP) activity, suggesting a distinct mechanism of mitochondrial dysfunction, which could explain, almost in part, the cognitive differences in aging. Investigating possible mechanisms responsible for this mitochondrial dysfunction, we found that mitochondrial proteostasis is more prone to failure in aged males, with a significant decrease in the protease activity of Lonp1, a key matrix mitochondrial protease degrading >50% of the mitochondrial proteome. To further reinforce these findings, we replicated key experiments in SAMP8 mice, a model of accelerated aging, obtaining consistent results that strengthen the robustness and generalization of our conclusions. These findings suggest that sex influences hippocampal aging at multiple levels, highlighting the need to consider sexual dimorphism in aging research. This study also emphasizes the critical role of mitochondrial proteostasis in maintaining mitochondrial function in aging in a sex-dependent manner. Understanding these differences could facilitate the development of sex-specific strategies to mitigate age-related cognitive decline and neurodegeneration.

Deregulation of E3 ubiquitin ligases is associated with increased proliferation and metastasis in prostate cancer (PCa); however, the underlying mechanisms remain largely unclear. This study aimed to explore the role of Fbxo2, a SKP1-Cullin-F-box (SCF) E3 ubiquitin ligase, in PCa progression. Analysis of prostate tissue samples revealed that Fbxo2 is downregulated in PCa, and higher Fbxo2 expression correlates with better patient prognosis. Functional assays conducted both in vitro and in vivo demonstrated that Fbxo2 reduces cell proliferation and metastasis in PCa. Using co-immunoprecipitation mass spectrometry (co-IP-MS), co-IP, western blotting, and ubiquitin assays, we identified that m6A reader YTHDF2, an oncoprotein that is upregulated in PCa, was a substrate of Fbxo2-mediated degradation. Notably, Fbxo2 mutants lacking the C-terminal region were less effective in promoting YTHDF2 ubiquitination and destruction. Furthermore, lysine 286 (K286) of YTHDF2 was identified as the key ubiquitination site. A series of rescue experiments revealed that silencing or overexpressing YTHDF2 modulated the effects of Fbxo2 knockdown or overexpression, confirming their functional interplay. Mechanistically, YTHDF2 enhanced the PCa progression and metastasis by modulating the m6A methylation of CDKN1C mRNA. Together, these findings suggest that Fbxo2 axis may serve as a potential prognostic marker and therapeutic target in PCa.