Dissociation between the expression of cGAS/STING and a senescence-associated signature in colon cancer.

OBJECTIVE: The effect of the cGAS/STING pathway on antitumor immunity and its connection to senescence in vivo necessitates further investigation. INTRODUCTION: Cellular senescence and its secretory phenotype (the SASP) are implicated in modulating the immune microenvironment of cancer possibly through the cGAS/STING pathway. METHODS: Gene expression data from paired colon cancer and adjacent non-malignant mucosa (98 patients, n = 196 samples; 65 patients, n = 130 samples) were analyzed for cGAS/STING and a senescence signature. Immunohistochemistry assessed cGAS/STING protein expression in 124 colorectal samples. RESULTS: Approximately one-quarter of patients displayed senescence profiles in both gene sets, yet without significantly correlating with cGAS/STING expression. Notably, cGAS expression was higher than STING in tumor tissue compared to non-malignant colonic mucosa. Protein analysis showed 83% positive cGAS expression and 39% positive STING expression, with discrepancies in expression patterns. Additionally, 15% of samples lacked both markers, while 35% exhibited positive staining for both. No significant correlations were found between cGAS/STING status and tumor stage, patient age, lymphovascular invasion, or lymph node involvement. CONCLUSIONS: Our findings demonstrate significant senescence marker expression in colorectal cancer samples but with no correlation with cGAS/STING.