DTX3L mediated ubiquitination of cGAS suppresses antitumor immunity in pancreatic cancer

The role of cGAS-STING pathway ubiquitination in innate immunity and multiple diseases

The cGAS-STING pathway is essential in innate immunity, especially in antiviral responses and cellular stress management. cGAS acts as a cytoplasmic DNA sensor by initiating the synthesis of the second messenger cyclic GMP-AMP synthase (cGAMP), which subsequently activates the STING pathway, leading to the production of type I interferons and other cytokines, as well as the activation of inflammatory mediators. Recent studies have demonstrated that ubiquitination changes closely regulate the function of the cGAS-STING pathway. Ubiquitination modifications influence the stability and activity of cGAS and STING, while also influencing the accuracy of the immune response by adjusting their degradation and signal intensity. E3 ubiquitin ligase specifically facilitates the degradation or modulates the signaling of cGAS-STING-associated proteins via ubiquitination alterations. Furthermore, the ubiquitination of the cGAS-STING pathway serves distinct functions in various cell types and engages with NF-κB, IRF3/7, autophagy, and endoplasmic reticulum stress. This ubiquitin-mediated regulation is crucial for sustaining the balance of innate immunity, while excessive or inadequate ubiquitination can result in autoimmune disorders, cancers, and viral infections. An extensive examination of the ubiquitination process within the cGAS-STING pathway elucidates its specific regulatory mechanisms in innate immunity and identifies novel targets for the intervention of associated diseases.

cGAS/STING pathway and gastrointestinal cancer: Mechanisms and diagnostic and therapeutic targets (Review)

The health of individuals is seriously threatened by intestinal cancer, which includes pancreatic, colorectal, esophageal, gastric and gallbladder cancer. Most gastrointestinal cancers do not have typical and specific early symptoms, and lack specific and effective diagnostic markers and treatment methods. It is critical to understand the etiology of gastrointestinal cancer and develop more efficient methods of diagnosis and treatment. The cyclic GMP‑AMP synthase (cGAS)/stimulator of interferon genes (STING) pathway serves a crucial role in the occurrence, progression and treatment of gastrointestinal cancer. The present review focuses on the latest progress regarding the role and mechanism of the cGAS/STING pathway in gastrointestinal cancer, and discusses treatment approaches and related applications based on the cGAS/STING signaling pathway. In order to improve the knowledge of the connection between the cGAS/STING pathway and gastrointestinal cancer, aid the diagnosis and treatment of gastrointestinal cancer, and lessen the burden on patients and society, the present review also discusses future research directions and existing challenges regarding cGAS/STING in the study of gastrointestinal cancer.

Expression, potential biological behaviour and clinical significance of MCM3 in pancreatic adenocarcinoma: a comprehensive study integrating high throughput sequencing, CRISPR screening and in-house immunohistochemistry

BACKGROUND

Minichromosome maintenance complex component 3 (MCM3) plays a key role in various tumours. However, it remains largely unknown what the specific role and clinical significance of MCM3 in pancreatic adenocarcinoma (PAAD) are.

MATERIALS AND METHODS

We integrated high-throughput data from PAAD worldwide to analyse the expression level of MCM3 mRNA. We used immunohistochemistry to analyse MCM3 protein expression levels in 145 cases in the PAAD group and 29 cases in the non-PAAD group. We also mainly analysed the necessity of MCM3 for PAAD growth based on CRISPR screen data. In addition, we used enrichment analysis and protein-protein interaction networks to explore the molecular mechanism of MCM3 in PAAD. We also analysed the correlation between MCM3 expression, components of the immune microenvironment in PAAD tissue and clinical prognosis.

RESULTS

In PAAD, we observed for the first time that MCM3 was significantly highly expressed at both the mRNA (SMD = 0.67, 95% CI: 0.38 ∼ 0.96) and the protein level (p < 0.05). The mRNA (AUC = 0.78, 95% CI: 0.74 ∼ 0.81; sensitivity = 0.66, 95% CI: 0.55 ∼ 0.76; specificity = 0.76, 95% CI: 0.67 ∼ 0.84) and protein (AUC = 0.929) expression levels of MCM3 had a good ability to distinguish between PAAD and non-PAAD tissue. There was heterogeneity reflected by the differential expression of MCM3 protein in PAAD cells. MCM3 played an essential role in PAAD growth, through abnormal DNA replication, p53 signalling and cell cycle checkpoints. PAAD with high MCM3 expression was sensitive to c-75, brivanib, flavopiridol and VNLG/124 drugs, with stable molecular docking models.

CONCLUSION

MCM3 is likely to be a critical element in promoting the initiation and growth of PAAD. Flavopiridol may exert its anti-PAAD effect through the interaction between MCM3, classic CDK1 targets in the cell cycle checkpoint and p53 pathway as well as related molecules in other pathways.