Adiponectin Inhibits the Progression of Obesity-Associated Papillary Thyroid Carcinoma Through Autophagy.

[CONTEXT] Obesity is a risk factor for the development of papillary thyroid cancer (PTC). However, the molecular mechanisms by which obesity promotes PTC are unclear.

[OBJECTIVE] This study aims to identify adipokines that are linked to PTC progression.

[METHODS] An adipokine antibody array was used to determine the serum levels of 40 adipokines in normal-weight and obese PTC patients. Enzyme-linked immunosorbent assay was used to determine the serum levels of adiponectin. Recombinant human adiponectin was produced by human adipose-derived stem cells and used to treat PTC cells. Cell proliferation and migration were evaluated using the CCK8 and Transwell assays. Bioinformatics analysis was used to predict mechanisms by which adiponectin affects PTC.

[RESULTS] Adipokines differentially expressed between normal-weight and obese patients showed a gender-dependent pattern. Obese PTC patients had a significantly lower serum adiponectin level than normal-weight patients, especially in female individuals. Adiponectin levels were negatively correlated with aggressive features of PTC, including tumor diameter > 1 cm, extrathyroidal extension, and lymph node metastasis. Recombinant human adiponectin inhibited the proliferation and migration of human PTC cells in vitro. Bioinformatics analysis identified adiponectin receptor 2 (ADIPOR2) and the autophagy pathway as possible mediators of adiponectin function in TC. In vitro experiments confirmed that adiponectin activated autophagy in PTC cells. These findings shed new lights into the role and mechanisms of adiponectin in TC pathogenesis.

[CONCLUSION] Adiponectin is involved in development of obesity-related PTC. Adiponectin can directly inhibit thyroid cancer growth and metastasis through the autophagy pathway.