Metformin is the most widely used therapeutic for Type 2 diabetes, and it has also been shown to have antineoplastic properties by modulating tumor growth and T cell responses. Immunotherapy for cancer is becoming a promising approach to treat metastatic disease because of the rising pre-clinical and clinical studies targeting checkpoint inhibitors. We hypothesize that metformin antineoplastic activity is due to inhibition of tumor growth. The goal of our approach is to determine if metformin administration inhibits tumor growth and also influences immune cells. To determine the influence of metformin on the anti-tumor response we used three different murine cancer cell lines including two breast cancer (4T1 & D2F2E2) and one lung cancer (LL2) lines. Our results show that with metformin treatment, the growth of these cells was suppressed. We also found that metformin can modulate mouse CD8 T cell activation in vitro in a dose dependent manner. Our findings will be useful for further studies to evaluate the effect of metformin on anti-tumor immunes response in vivo.
