Overexpressing lipid raft protein STOML2 modulates the tumor microenvironment via NF-κB signaling in colorectal cancer.

ABSTRACT

Colorectal cancer (CRC) is characterized by a complex tumor inflammatory microenvironment, while angiogenesis and immunosuppression frequently occur concomitantly. However, the exact mechanism that controls angiogenesis and immunosuppression in CRC microenvironment remains unclear. Herein, we found that expression levels of lipid raft protein STOML2 were increased in CRC and were associated with advanced disease stage and poor survival outcomes. Intriguingly, we revealed that STOML2 is essential for CRC tumor inflammatory microenvironment, which induces angiogenesis and facilitates tumor immune escape simultaneously both in vitro and in vivo. Moreover, tumors with STOML2 overexpression showed effective response to anti-angiogenesis treatment and immunotherapy in vivo. Mechanistically, STOML2 regulates CRC proliferation, angiogenesis, and immune escape through activated NF-κB signaling pathway via binding to TRADD protein, resulting in upregulation of CCND1, VEGF, and PD-L1. Furthermore, treatment with NF-κB inhibitor dramatically reversed the ability of proliferation and angiogenesis. Clinically, we also observed a strong positive correlation between STOML2 expression and Ki67, CD31, VEGFC and PD-1 of CD8+T cell expression. Taken together, our results provided novel insights into the role of STOML2 in CRC inflammatory microenvironment, which may present a therapeutic opportunity for CRC.