Autophagy: A potential target for thyroid cancer therapy (Review).

The sharply increasing incidence of thyroid cancer has attracted considerable attention over the last few years. The combination of surgery, radioiodine ablation and thyroid-stimulating hormone suppression is usually efficient for the majority of thyroid tumors. However, advanced thyroid cancer that is recurrent, metastatic and 131I-refractory, or medullary thyroid cancer, pose a therapeutic challenge. Autophagy is a process that metabolizes damaged cytoplasmic organelles and long-lived proteins in order to recycle cellular materials and maintain homeostasis. It has been confirmed that autophagy plays a dual role during cancer development, progression and treatment, mainly depending on the type and stage of the tumor. Autophagy modulation has become a potential therapeutic target for diverse diseases. The mechanism of thyroid tumorigenesis and cancer progression was largely demonstrated to be correlated with the dysregulation of the Ras/Raf/mitogen-activated protein kinase kinase/extracellular signal-regulated kinase and the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin pathways, as well as with abnormal epigenetic modifications. Those mechanisms are associated with autophagy regulation and may be beneficial for the treatment of advanced thyroid cancer. However, the number of available studies on the role of autophagy in thyroid cancer development, progression and treatment outcome, is currently limited. The aim of this review was to elaborate on the relevant knowledge and future prospectives of autophagy in the treatment of thyroid cancer.