Estrogen Receptor α Induces Prosurvival Autophagy in Papillary Thyroid Cancer via Stimulating Reactive Oxygen Species and Extracellular Signal Regulated Kinases

Context: The incidence of papillary thyroid cancer (PTC) shows a predominance in females, with a male:female ratio of 1:3, and none of the known risk factors are associated with gender difference. Increasing evidence indicates a role of estrogen in thyroid tumorigenesis, but the mechanism involved remains largely unknown. Objective: This study aimed to assess the contribution of autophagy to estrogen receptor α (ERα)-mediated growth of PTC. Design: The expression of ERα in thyroid tissue of patients with PTC tissues was analyzed. Cell viability, proliferation, and apoptosis were evaluated after chemical and genetic inhibition of autophagy. Autophagy in PTC cell lines BCPAP and BCPAP-ERα was assessed. Results: ERα expression was increased in PTC tissues compared with the adjacent nontumor tissues. Estrogen induced autophagy in an ERα-dependent manner. Autophagy induced by estrogen/ERα is associated with generation of reactive oxygen species, activation of ERK1/2, and the survival/growth of PTC cells. Chemi...