Autophagy and thyroid cancer

Abstract

This review provides the up-to-date physiological, pathophysiological, and carcinogenic roles of autophagy in the thyroid. The data on its physiological roles are mainly obtained with genetically engineered mice, demonstrating the importance of autophagy for the maintenance of cell homeostasis and survival as well as provision of building blocks for sufficient synthesis of proteins such as thyroglobulin. Positive and negative controls of autophagic activity by thyrotropin and thyroid hormone, respectively, are now apparent. In thyroid cancer, there is no published study on the role for autophagy in the initiation/development of thyroid cancer, and there exist many inconsistent data regarding its role in established thyroid cancer behavior. For example, definitive conclusions remain to be elucidated regarding the level of autophagic activity in thyroid cancer cells and the effect of autophagy inducers/inhibitors on cancer cell survival/proliferation. Especially, when autophagy is targeted in novel cancer therapeutics, some studies show its pro-survival, but others its anti-survival or context-dependent, effects on thyroid cancer cells. Further studies are in the future necessary to further elucidate the potential of autophagy as a therapeutic target for thyroid cancer.