Abstract
BACKGROUND: Transforming growth factor-β (TGF-β) plays well-established roles in cancer cell invasion and epithelial-mesenchymal transition (EMT); however, its role in thyroid carcinoma (TC) remains unclear. This study aimed to evaluate the effects of TGF-β on EMT in TC and determine its underlying mechanisms. METHODS: Treatment of TC cell lines with TGF-β the morphology of thyroid cancer cells changed, Immunofluorescence staining revealed that the localization of E-cadherin shifted from the cell membrane to the cytoplasm, and the fluorescence intensity decreases. Wound-healing assay in BCPAP and TPC-1 revealed that migration ability was significantly higher in the TGF-β (5 ng/mL) treatment group than in the control group (P < 0.01). RESULTS: Transwell assays showed that the invasive abilities of TGF-β-treated BCPAP, TPC-1, and K1 cells were 7-, 10-, and 6-fold higher than those of the control group, respectively (P < 0.05). After TGF-β treatment, mRNA levels of SNAI1 significantly increased in TPC-1 and BCPAP cell lines. Treatment of TC cell lines with TGF-β downregulated the epithelial marker E-cadherin and upregulated the mesenchymal markers N-cadherin and vimentin, at the mRNA level. Western blotting indicated similar results at the protein level, TSH could enhance this process. CONCLUSIONS: TGF-β promotes EMT-like phenotypic changes in thyroid cancer cells, accompanied by upregulation of SNAI1 and EMT-related markers, which is enhanced by TSH. Overall, this study provides a basis for the development of therapeutic strategies for TC targeting the EMT.