The inhibitive potential of metformin on extracellular calcium signaling might be important for the additional effect of combined treatment by metformin and miR-708-5p mimic.26 In addition, metformin was reported to have oncogenic target other than miR-708-5p in prostate cancer cells such as c-Myc21 and AR,27 which could also contribute to the induction of apoptosis. This evidence concerns the gene AR and Familial prostate cancer.