BAG2 Inhibits Cervical Cancer Progression by Modulating Type I Interferon Signaling through Stabilizing STING.

Cervical cancer possesses high morbidity and mortality rates, and a comprehensive understanding of its molecular underpinnings is essential for advancing clinical management strategies. The innate immune sensor STING, which activates type I interferon signaling, plays a pivotal role in enhancing anti-tumor activity. Despite increased attention to STING's involvement in cervical cancer, the regulatory mechanisms governing its protein homeostasis remain poorly understood. In this study, it is found that the BAG2-STUB1 complex regulates ubiquitin proteasomal degradation of STING, which affects the development of cervical cancer. Mechanistically, BAG2 inhibits ubiquitination of STING and stabilizes it by interacting with STING. Specifically, BAG2 inhibits STUB1 from attaching the K48-linked ubiquitin chains at K338 and K370 of STING by forming a complex with STUB1. Functionally, enhanced BAG2 expression suppresses cervical cancer progression by activating the type I interferon pathway in a STING-dependent manner. Notably, clinical cervical cancer samples revealed a positive correlation between BAG2 and STING levels, with low BAG2 expression is strongly linked to advanced disease and poor prognosis in cervical cancer. Collectively, these findings elucidate the molecular mechanism by which the BAG2-STUB1 complex regulates STING homeostasis, underscoring BAG2's potential as a diagnostic biomarker and therapeutic target in cervical cancer.