DOT1L-mediated RAP80 methylation promotes BRCA1 recruitment to elicit DNA repair.

Breast Cancer Type 1 Susceptibility Protein (BRCA1) is a tumor-suppressor protein that regulates various cellular pathways, including those that are essential for preserving genome stability. One essential mechanism involves a BRCA1-A complex that is recruited to double-strand breaks (DSBs) by RAP80 before initiating DNA damage repair (DDR). How RAP80 itself is recruited to DNA damage sites, however, is unclear. Here, we demonstrate an intrinsic correlation between a methyltransferase DOT1L-mediated RAP80 methylation and BRCA1-A complex chromatin recruitment that occurs during cancer cell radiotherapy resistance. Mechanistically, DOT1L is quickly recruited onto chromatin and methylates RAP80 at multiple lysines in response to DNA damage. Methylated RAP80 is then indispensable for binding to ubiquitinated H2A and subsequently triggering BRCA1-A complex recruitment onto DSBs. Importantly, DOT1L-catalyzed RAP80 methylation and recruitment of BRCA1 have clinical relevance, as inhibition of DOT1L or RAP80 methylation seems to enhance the radiosensitivity of cancer cells both in vivo and in vitro. These data reveal a crucial role for DOT1L in DDR through initiating recruitment of RAP80 and BRCA1 onto chromatin and underscore a therapeutic strategy based on targeting DOT1L to overcome tumor radiotherapy resistance.

Caspase-4 in glioma indicates deterioration and unfavorable prognosis by affecting tumor cell proliferation and immune cell recruitment.

Gliomas are the most common malignant tumors of the central nervous system, accounting for approximately 80% of all malignant brain tumors. Accumulating evidence suggest that pyroptosis plays an essential role in the progression of cancer. Unfortunately, the effect of the pyroptosis-related factor caspase-4 (CASP4) on immunotherapy and drug therapy for tumors has not been comprehensively investigated. In this study, we systematically screened six hub genes by pooling differential pyroptosis-related genes in The Cancer Genome Atlas (TCGA) glioma data and the degree of centrality of index-related genes in the protein-protein interaction network. We performed functional and pathway enrichment analyses of the six hub genes to explore their biological functions and potential molecular mechanisms. We then investigated the importance of CASP4 using Kaplan-Meier survival analysis of glioma patients. TCGA and the Chinese Glioma Genome Atlas (CGGA) databases showed that reduced CASP4 expression leads to the potent clinical deterioration of glioma patients. Computational analysis of the effect of CASP4 on the infiltration level and recruitment of glioma immune cells revealed that CASP4 expression was closely associated with a series of tumor-suppressive immune checkpoint molecules, chemokines, and chemokine receptors. We also found that aberrant CASP4 expression correlated with chemotherapeutic drug sensitivity. Finally, analysis at the cellular and tissue levels indicated an increase in CASP4 expression in glioma, and that CASP4 inhibition significantly inhibited the proliferation of glioma cells. Thus, CASP4 is implicated as a new prognostic biomarker for gliomas with the potential to further guide immunotherapy and chemotherapy strategies for glioma patients.

The LncRNA signature associated with cuproptosis as a novel biomarker of prognosis in immunotherapy and drug screening for clear cell renal cell carcinoma.

Cuproptosis is a new form of cell death, the second form of metal ion-induced cell death defined after ferroptosis. Recently, cuproptosis has been suggested to be associated with tumorigenesis. However, the relationship between cuproptosis and patient prognosis in clear cell renal cell carcinoma (ccRCC) in the context of immunotherapy remains unknown. The aim of this study was to investigate the correlation between cuproptosis-related long non-coding RNA (lncRNA) and ccRCC in terms of immunity as well as prognosis. Clinical information on lncRNAs associated with differences in cuproptosis genes in ccRCC and normal tissues was collected from The Cancer Genome Atlas (TCGA) dataset. Univariate Cox regression was used to screen lncRNAs. A total of 11 lncRNAs closely associated with cuproptosis were further screened and established using the least absolute shrinkage and selection operator (LASSO) algorithm and multivariate Cox regression, and the samples were randomly divided into training and test groups. A risk prognostic model was constructed using the training group, and the model was validated using the test group. We investigated the predictive ability of the prognostic risk model in terms of clinical prognosis, tumor mutation, immune escape, immunotherapy, tumor microenvironment, immune infiltration levels, and tumor drug treatment of ccRCC. Using the median risk score, patients were divided into low and high-risk groups. Kaplan-Meier curves showed that the overall survival (OS) of patients in the high-risk group was significantly worse than low-risk group (p < 0.001). Receiver operating characteristic (ROC) curves further validated the reliability of our model. The model consistently and accurately predicted prognosis at 1, 3, and 5 years, with an AUC above 0.7. Tumor cell genes generally precede morphological abnormalities; therefore, the model we constructed can effectively compensate for the traditional method of evaluating the prognosis of patients with renal cancer, and our model was also clinically meaningful in predicting ccRCC staging. In addition, lower model risk scores determined by mutational load indicated a good chance of survival. The high-risk group had greater recruitment of immune cells, while the anti-immune checkpoint immunotherapy was less efficacious overall than that of the low-risk group. Tumor and immune-related pathways were enriched, and anti-tumor agents were selected to improve the survival of ccRCC. This prognostic risk model is based on the levels of cuproptosis-associated lncRNAs and provides a new perspective in the clinical assessment and precise treatment of ccRCC.

Platelet-derived microparticles stimulated by anti-ß2GPI/ß2GPI complexes induce pyroptosis of endothelial cells in antiphospholipid syndrome.

Platelet microparticles (PMPs) are vesicles that are released by platelets into the extracellular space and play a role in antiphospholipid antibody syndromes. PMPs have recently been recognized as a new and viable cell. There is growing evidence that the anti-ß2 glycoprotein (GPI)/ß2GPI complex is associated with aberrant activation of PMPs. Although studies suggest that aberrant activation of PMPs may lead to inflammatory necrosis of endothelial cells, the underlying mechanisms remain unclear. We found that although the difference in the number of PMPs was not statistically significant, NLR family pyrin domain containing 3 (NLRP3) within PMPs was increased during stimulation of anti-ß2GPI/ß2GPI complexes. Furthermore, we demonstrated that anti-ß2GPI/ß2GPI complex-induced PMPs effectively stimulated endothelial cell pyroptosis via the NLRP3/nuclear factor (NF)-κB/gasdermin D (GSDMD) signaling pathway as well as the NLRP3/Caspase-1 signaling pathway. Additionally, inhibition of NLRP3 expression in PMPs effectively reduced the inflammatory response and pyroptosis in endothelial cells. Our data suggest that PMPs aberrantly activated by anti-ß2GPI/ß2GPI complexes play a vital role in endothelial cell pyroptosis, and these studies provide major insights into the mechanisms of thrombosis during the treatment of antiphospholipid antibody syndrome.

What is the context? Antiphospholipid syndrome (APS), an acquired autoimmune disease of unknown etiology. Clinical manifestations include arteriovenous thrombosis, recurrent miscarriages and thrombocytopenia. Endothelial cell damage is common in APSAnti-ß2 glycoprotein I antibody, one of the most common APS antibodies, is the main target antigen of anti-ß2GPI. Studies have shown that the anti-ß2GPI/ß2GPI complex accelerates inflammatory cell necrosis.Pyroptosis, also known as inflammatory cell necrosis, is a new form of cell death. Pyroptosis is caused by the activation of the NLRP3 inflammasome, which manifests itself as swelling, lysis and perforation of the cell membrane.Platelet micro-particles (PMPs) are vesicular components that are released extracellularly by platelet activation and are the most abundant and common type of circulating particles in the blood, causing an inflammatory response in the endothelium. There is limited evidence that anti-ß2GPI/ß2GPI complexes can accelerate endothelial cell pyroptosis by mediating platelet activation to produce PMPs. However, more research is needed to investigate the specific mechanisms by which PMPs cause endothelial cell pyroptosis.What is new? This is the first study on the role of NLRP3 in PMPs. NLRP3 expression in PMPs was increased by stimulation of anti-ß₂GPI/ß₂GPI complexes.NLRP3 in PMPs is closely associated with GSDMD-N, a protein involved in endothelial pyroptosis.Anti-ß₂GPI/ß₂GPI stimulated PNPs induce pyroptosis via NLRP3/NF-κB/GSDMD and NLRP3/Caspase-1/IL-1ß axis.What is the impact? The aim of this study was to investigate the specific mechanism of endothelial cell pyroptosis induced by platelet-released PMPs activated by anti-ß₂GPI/ß₂GPI complexes. This finding provides new ideas on the mechanism of endothelial cell scorching in APS and provides a new drug target for the clinical treatment of APS.

TIMELESS is a key gene mediating thrombogenesis in COVID-19 and antiphospholipid syndrome.

Abnormal coagulation and increased risk of thrombosis are some of the symptoms associated with COVID-19 severity. Anti-phospholipid antibodies (aPLs) present in critically ill COVID-19 patients contribute to systemic thrombosis. The aim of this study was to identify key common genes to characterize genetic crosstalk between COVID-19 and antiphospholipid syndrome (APS) using bioinformatics analysis and explore novel mechanisms of immune-mediated thrombosis in critically ill COVID-19 patients. The transcriptome data of mononuclear cells from severe COVID-19 patients and APS patients were evaluated to obtain the common genes. The protein-protein interaction network and cytoHubba module analysis in Cytoscape software were used to find the associated hinge genes and hub genes. Among the common differentially expressed genes, TIMELESS depletion was identified only in patients with severe COVID-19 and not in patients with mild COVID-19, and it was validated with the GSE159678 dataset. Functional analyses using gene ontology terms and the Kyoto Encyclopedia of Genes and Genomes pathway suggested that TIMELESS might contribute to the production of antiphospholipid antibody and thrombosis in both COVID-19 and APS patients. The potential role of TIMELESS and autophagy genes in momonuclear cells were further investigated, and GSK3B was found to be associated with TIMELESS. Autophagy targeting agents have a therapeutic potential against COVID-19 and thrombogenesis in APS, which may be related to the role of autophagy genes in the modification of circadian clock proteins. Interference with TIMELESS and other genes associated with it to regulate autoantibody expression may be a potential strategy for immunotherapy against thrombogenesis in severe COVID-19 patients.

SNAP25 is a potential prognostic biomarker for prostate cancer.

BACKGROUND: Prostate cancer (PCa) is one of the most lethal cancers in male individuals. The synaptosome associated protein 25 (SNAP25) gene is a key mediator of multiple biological functions in tumors. However, its significant impact on the prognosis in PCa remains to be elucidated. METHODS: We performed a comprehensive analysis of the Cancer Genome Atlas dataset (TCGA) to identify the differentially expressed genes between PCa and normal prostate tissue. We subjected the differentially expressed genes to gene ontology analysis and Kyoto Encyclopedia of Genes and Genomes functional analysis, and constructed a protein-protein interaction network. We then screened for pivotal genes to identify the hub genes of prognostic significance by performing Cox regression analysis. We identified SNAP25 as one such gene and analyzed the relationship between its expression in PCa to poor prognosis using GEPIA interactive web server. RESULTS: TCGA database demonstrated that SNAP25 was significantly downregulated in PCa. The progressive decrease in SNAP25 expression with the increase in the clinical staging and grading of PCa demonstrates that reduced SNAP25 expression considerably exacerbates the clinical presentation. Our findings confirm that SNAP25 expression strongly correlates with overall survival, which was determined using the Gleason score. We also validated the role of SNAP25 expression in the prognosis of patients with PCa. We used Gene Set Enrichment and Gene Ontology analyses to evaluate the function of SNAP25 and further explored the association between SNAP25 expression and tumor-infiltrating immune cells using the Tumor Immune Assessment Resource database. We found for the first time that SNAP25 is involved in the activation, differentiation, and migration of immune cells in PCa. Its expression was positively correlated with immune cell infiltration, including B cells, CD8+ T cells, CD4+ T cells, neutrophils, dendritic cells, macrophages, and natural killer cells. SNAP25 expression also positively correlated with chemokines/chemokine receptors, suggesting that SNAP25 may regulate the migration of immune cells. In addition, our experimental results verified the low expression of SNAP25 in PCa cells. CONCLUSION: Our findings indicate a relationship between SNAP25 expression and PCa, demonstrating that SNAP25 is a potential prognostic biomarker due to its vital role in immune infiltration.