25-Hydroxyvitamin D ₃ 1α-Hydroxylase and Vitamin D Receptor Expression in Papillary Thyroid Carcinoma

Vitamin D receptor (VDR) and 25-hydroxyvitamin D3 1-alpha-hydroxylase expression have recently been shown to be upregulated in several tumors and thought to represent an important endogenous response to tumor progression. Little is known about the expression of these proteins in thyroid carcinoma, although previous reports have documented evidence of the biological effect of vitamin D in thyroid cells. Using paraffin-embedded and frozen sections of papillary thyroid carcinoma, we utilized real-time quantitative RT-PCR and immunohistochemistry to characterize the expression of VDR and 1-alpha-hydroxylase in thyroid follicular cells, with special emphasis on papillary thyroid carcinoma (PTC). VDR and 1-alpha-hydroxylase expression were increased in PTC compared with normal thyroid tissue and especially high in areas of lymphocyte infiltration. Expression of VDR and 1-alpha-hydroxylase in PTC may be compatible with an overall favorable prognosis for this tumor type and may constitute important prerequisites for using vitamin D and/or vitamin D analogs in the treatment of PTC.