Abstract
Thyroid cancer has the fastest rising incidence among cancers, especially for differentiated thyroid carcinoma (DTC). Although the prognosis of DTC is relatively good, if it changes to anaplastic thyroid carcinoma (ATC), the prognosis will be very poor. The prognosis of DTC is largely depending on the degree of cell differentiation and proliferation. However, whether the vitamin D receptor (VDR) plays a role in regulating the proliferation and the differentiation of DTC cells is unclear. In the present study, we found that VDR was upregulated in DTC tissues compared to the adjacent non-cancerous tissue. Knockdown of VDR increased proliferation and decreased differentiation proliferation in DTC cells in vitro as well as DTC cell-derived xenografts in vivo. In contrast, overexpression of VDR had an opposite effect. Knockdown of E-cadherin abolished VDR-induced suppression of proliferation and enhancement of differentiation of the DTC cells. Knockdown of β-catenin partially reversed the effect of the VDR knockdown. VDR increases the levels of E-cadherin in the plasma membrane and decreases the levels of β-catenin in the nucleus. VDR binds to E-cadherin and β-catenin in the plasma membrane of the DTC cell. Taken together, VDR inhibits DTC cell proliferation and promotes differentiation via regulation of the E-cadherin/β-catenin complex, potentially representing novel clues for a therapeutic strategy to attenuate thyroid cancer progression.