IL-6 induced proliferation and cytotoxic activity of CD8(+) T cells is elevated by SUMO2 overexpression.

T cells play an important role in adaptive immune responses that destroy pathogens or infected cells. Therefore, regulation of T cell activity is important in various diseases, such as autoimmune diseases, hypersensitivity, and cancer. The conjugation of small ubiquitin-related modifier (SUMO) is a post-translational protein modification that regulates activity, stability, and subcellular translocation of target proteins. In this study, CD8(+) T cells overexpressing SUMO2 showed greater proliferation and cytotoxic activity against tumor cells in the presence of IL-6 than wild-type CD8(+) T cells in vitro. These CD8(+) T cell functions were suppressed during treatment with MEK1 or PI3K-specific inhibitors. Therefore, our findings suggest that IL-6-derived signaling pathways, including the MEK1 and PI3K pathways, are upregulated by SUMO2 overexpression. However, transgenic expression of SUMO2 in T cells did not modulate Th1/2 balance. Collectively, our results showed that SUMO2-Tg promotes cytotoxic activity against tumor cells by increasing the proliferation and cytotoxicity of CD8(+) T cells.