Insulin and cancer (Review)

Although the molecular mechanisms of insulin action on many physiological a nd biochemical processes are far from being completely understood, little d oubt exists about the involvement: of insulin in tumoural processes. Indeed , increased insulin production (either directly by the tumour in an ectopic fashion, or indirectly by stimulation of the pancreatic secretion) is a co mmon phenomenon during cancer development. Paradoxically, the increased pro duction and circulating levels of the hormone are associated with a decreas e in sensitivity which leads to insulin resistance in the non-tumoural tiss ues, resulting in hyperlipaemia and profound alterations in carbohydrate an d lipid metabolism. In addition to these effects on the host, insulin can a ctually increase the incidence of neoplasias and promote tumour growth. Thi s is probably related to the signaling pathway of the hormone, which shares many elements with that of several growth factors. In addition, insulin si gnaling directly interacts with that of the ms oncogene. We review the invo lvement of insulin in cancer from a multidisciplinary point of view, with t he aim of encouraging the design of future therapeutic options for cancer t reatment.