The Antitumor Effects of Metformin on Gastric Cancer In Vitro and on Peritoneal Metastasis.

Background/Aim: Gastric cancer (GC) with peritoneal metastasis remains difficult to treat. The antidiabetic drug metformin exerts various antitumor effects via the 5'-adenosine monophosphate-activated protein kinase (AMPK) pathway and nuclear factor-kappa B (NF-kappa B). Therefore, we evaluated the antitumor effects of metformin for GC in vitro and on peritoneal metastasis. Materials and Methods: The human GC cell lines MKN1, MKN45, KATO-III and SNU-1 were used. The antiproliferative effect was evaluated in vitro with 0.5 mM or 25 mM glucose and in vivo using tumor xenograft peritoneal models of metastasis. The protein expression of AMPK, liver kinase B1 (LKB1) and NF-kappa B in tumors was examined by western blotting. Results: Metformin inhibited cell proliferation in all GC lines and sensitivity was increased under low-glucose conditions in vitro. Metformin also suppressed peritoneal metastasis. In tumors, metformin reduced the numbers of proliferating cells and NF-kappa B expression, but a similar trend was not noted for AMPK. Conclusion: Metformin may be a useful drug for the treatment of GC with peritoneal metastasis.