Mitotic SENP3 activation couples with cGAS signaling in tumor cells to stimulate anti-tumor immunity

SUMO proteases: from cellular functions to disease

Posttranslational modification by small ubiquitin-like modifiers (SUMOs) is critical in regulating diverse cellular processes including gene expression, cell cycle progression, genome integrity, cellular metabolism, and inflammation and immunity. The covalent attachment of SUMOs to target proteins is highly dynamic and reversible through the concerted action of SUMO conjugating and deconjugating enzymes. In mammalian cells, sentrin-specific proteases (SENPs) are the most abundant family of deconjugating enzymes. This review highlights recent advances in our knowledge of the substrates and cellular and physiological processes controlled by SENPs. Notably, SENPs are emerging as significant players in cancer, as well as in other diseases, making them attractive targets for therapeutic intervention. Consequently, a growing amount of effort in the field is being directed towards the development of SENP inhibitors.

Development and validation of a mitotic catastrophe-related genes prognostic model for breast cancer

Background

Breast cancer has become the most common malignant tumor in women worldwide. Mitotic catastrophe (MC) is a way of cell death that plays an important role in the development of tumors. However, the exact relationship between MC-related genes (MCRGs) and the development of breast cancer is still unclear, and further research is needed to elucidate this complexity.

Methods

Transcriptome data and clinical data of breast cancer were downloaded from the Cancer Genome Atlas (TCGA) database and the Gene Expression Omnibus (GEO) database. We identified differential expression of MCRGs by comparing tumor tissue with normal tissue. Subsequently, we used COX regression analysis and LASSO regression analysis to construct the prognosis risk model of MCRGs. Kaplan-Meier survival curve and receiver operating characteristic (ROC) curve were used to evaluate the predictive ability of prognostic model. Moreover, the clinical relevance, gene set enrichment analysis (GSEA), immune landscape, tumor mutation burden (TMB), and immunotherapy and drug sensitivity analysis between high-risk and low-risk groups were systematically investigated. Finally, we validated the expression levels of genes involved in constructing the prognostic model through real-time quantitative polymerase chain reaction (RT-qPCR) at the cellular and tissue levels.

Results

We identified 12 prognostic associated MCRGs, four of which were selected to construct prognostic model. The Kaplan-Meier analysis suggested that patients in the high-risk group had a shorter overall survival (OS). The Cox regression analysis and ROC analysis indicated that risk model had independent and excellent ability in predicting prognosis of breast cancer patients. Mechanistically, a remarkable difference was observed in clinical relevance, GSEA, immune landscape, TMB, immunotherapy response, and drug sensitivity analysis. RT-qPCR results showed that genes involved in constructing the prognostic model showed significant abnormal expressions and the expression change trends were consistent with the bioinformatics results.

Conclusions

We established a prognosis risk model based on four MCRGs that had the ability to predict clinical prognosis and immune landscape, proposing potential therapeutic targets for breast cancer.

At the Crossroads of the cGAS-cGAMP-STING Pathway and the DNA Damage Response: Implications for Cancer Progression and Treatment

The evolutionary conserved DNA-sensing cGAS-STING innate immunity pathway represents one of the most important cytosolic DNA-sensing systems that is activated in response to viral invasion and/or damage to the integrity of the nuclear envelope. The key outcome of this pathway is the production of interferon, which subsequently stimulates the transcription of hundreds of genes. In oncology, the situation is complex because this pathway may serve either anti- or pro-oncogenic roles, depending on context. The prevailing understanding is that when the innate immune response is activated by sensing cytosolic DNA, such as DNA released from ruptured micronuclei, it results in the production of interferon, which attracts cytotoxic cells to destroy tumors. However, in tumor cells that have adjusted to significant chromosomal instability, particularly in relapsed, treatment-resistant cancers, the cGAS-STING pathway often supports cancer progression, fostering the epithelial-to-mesenchymal transition (EMT). Here, we review this intricate pathway in terms of its association with cancer progression, giving special attention to pancreatic ductal adenocarcinoma and gliomas. As the development of new cGAS-STING-modulating small molecules and immunotherapies such as oncolytic viruses involves serious challenges, we highlight several recent fundamental discoveries, such as the proton-channeling function of STING. These discoveries may serve as guiding lights for potential pharmacological advancements.

SENP1 Decreases RNF168 Phase Separation to Promote DNA Damage Repair and Drug Resistance in Colon Cancer

The DNA damage response (DDR) is essential for the maintenance of genomic stability. Protein posttranslational modifications play pivotal roles in regulating the DDR process. Here, we found that SUMOylated RNF168 undergoes liquid-liquid phase separation (LLPS), which restricts the recruitment of RNF168 to DNA damage sites, reduces RNF168-catalyzed H2A ubiquitination, restrains 53BP1 in nuclear condensates, and ultimately impairs nonhomologous DNA end joining repair efficiency. Sentrin/SUMO-specific protease 1 (SENP1) was identified as a specific deSUMOylase of RNF168, and it was highly expressed in colorectal adenocarcinoma. In response to DNA damage, SENP1 decreased RNF168 SUMOylation and prevented RNF168 from forming nuclear condensates, thus promoting damage repair efficiency and cancer cell resistance to DNA damaging agents. Moreover, high SENP1 expression correlated with poor prognosis in patients with cancer, and SENP1 depletion sensitized cancer cells to chemotherapy. In summary, these findings reveal DDR is suppressed by SUMOylation-induced LLPS of RNF168 and suggest that SENP1 is a potential target for cancer therapy.

SIGNIFICANCE

Sentrin/SUMO-specific protease 1 decreases RNF168 SUMOylation and liquid-liquid phase separation to promote DNA damage repair, safeguarding genomic integrity and driving chemotherapy resistance.