STING-mediated Syk Signaling Attenuates Tumorigenesis of Colitis-associated Colorectal Cancer Through Enhancing Intestinal Epithelium Pyroptosis

Background Stimulator of interferon genes (STING) has essential functions in the immune responses and can induce cancer cell apoptosis. However, it is not completely clear how STING plays a role in colitis-associated colorectal cancer (CAC) and whether it can trigger pyroptosis during the tumorigenesis of CAC. Methods To investigate the role of STING-modulated pyroptosis in the development of CAC, STING knockout and Wild type mice were challenged with azoxymethane (AOM) and dextran sodium sulfate (DSS) to establish a murine CAC model. STING pharmacological agonist was used to further study the functions of STING signaling in the tumorigenesis. Moreover, STING endogenous ligand was employed to verify the effects of STING in human colon cancer cells. Results STING deficiency mice were more susceptible to CAC by reducing pyroptosis of tumor cells, whereas overactivation of STING with the agonist suppressed tumorigenesis of CAC. STING also managed CAC development by modulating tumor cells proliferation, adhesion, and invasion, as well as inflammatory response. The ex vivo studies indicated that STING could induce pyroptosis via spleen tyrosine kinase (Syk), and Syk knockdown weakened such pyroptotic tumor cells death. In addition, the visible physical interaction between STING and Syk was observed in colorectal tumor samples of CAC patients. Conclusions STING-mediated Syk signaling may regulate the tumorigenesis of CAC by modulating pyroptosis of tumor cells, and modulation of STING/Syk serves as a novel therapeutic strategy for CAC therapy.