Administration of metformin to increase the efficacyof chemotherapy regimen in cancers; a new look toan old drug

Chemotherapeutic agents are still the major and most common therapy to prevent tumor growth. These drugs have various adverse effects in different organs in addition to systemic effects. Finding more specific and effective drugs or new adjuvant therapeutic substance is needed to improve the success rate. Several studies have proposed the possible mechanisms of anti-neoplastic of metformin, however, its exact mechanism is still obscure. The suggested mechanisms are; alteration in the host metabolic environment after administration of metformin, such as decreases in insulin-dependent stimulation of tumor growth or direct effect on cancer cells, such as the impact on adenosine monophosphate (AMP)-activated protein kinase signaling pathway. Metformin, as an adjuvant therapy, synergistically exerts growth inhibitory effects against cell growth and can induce cell apoptosis in an animal model. Adding metformin to the chemotherapy regimen may reduce resistance and enhance therapeutic efficacy.