Novel recombinant protein PK5-Gal-3C enhances the anti-tumor activity of T cells via binding with TRPV2

Investigating strategies to enhance T cell effector function can improve the adoptive immune responses to tumors and complement existing tumor immunotherapies. Here, we present a novel artificially designed recombinant protein, PK5-Gal-3C, which is composed of the fifth kringle domain of plasminogen (PK5) and the C-terminal carbohydrate-recognition domain of galectin-3 (Gal-3C). This protein exhibited potent anti-tumor activity by significantly enhancing T cell effector function. Specifically, PK5-Gal-3C directly activated T cells by binding to glycosylated TRPV2 via Gal-3C, a thermosensitive calcium-permeable cation channel, thereby promoting the influx of calcium ions to enhance T cells cytotoxicity via the activation of c-Jun. Correspondingly, inhibition of TRPV2 or c-Jun impaired the cytotoxicity of T cell mediated by PK5-Gal-3C. Additionally, PK5-Gal-3C demonstrated significant anti-tumor activity by enhancing T cell tumor infiltration and cytotoxicity in a mouse model, as well as improving the anti-tumor efficacy of CAR-T cells in solid tumors. In summary, PK5-Gal-3C is a safe and potent anti-tumor agent with promising potential for T cell-mediated cancer immunotherapy.