Anti-diabetic drug metformin: challenges and perspectives for cancer therapy.

Metformin, a biguanide, is a commonly administered drug for the management of type 2 diabetes mellitus. The drug received tremendous recognition, when retrospective studies proved metformin-associated reduction in cancer risk. Metformin has potential anticancer effects and an ability to suppress tumor growth both in vitro and in vivo. Activation of LKB1/AMPK pathway and cancer stem cell destruction along with cell cycle arrest and apoptosis induction are the proposed mechanisms of anticancer potential of metformin. Nanotechnology approaches have also been adopted for metformin delivery to cancer cells. This review directs on the application of metformin for the therapy of various cancers and also the different pathways responsible for the metformin derived anticancer effect. It also focuses on the pharmacological applications of metformin and the nanotechnology approaches for metformin delivery.