The possible effect of calcitriol on NDRG2 (N-Myc downstream regulated gene-2) and NIS (sodium-iodide symporter) gene expressions in undifferantiated human anaplastic thyroid cancer cell line

Background: Anaplastic thyroid cancer is one of the most agressive neoplasm. The loss of expressions in sodium-iodide symporter and TSH-receptor leads to failed conventional therapies such as thyroidectomy and radioactive iodide treatment. Despite surgery, radiotherapy and chemotherapy agents used in combination with aggressive multimodal therapies, the survival rate is extremely low. Thus, it is important to develop tumor growth inhibiting and differantiation inducing agents which can be used with chemotherapeutics that have low cytotoxicity. Aim: The aim of this study is to compare the possible difference of N-myc Downstream Regulated Gene-2 (NDRG2) and Sodium-Iodide Symporter (NIS) gene expressions in Nthy-ori-3-1 and 8505C cells and to investigate the possible effects of 1,25- dihydroxyvitamin D3 (calcitriol) on cell viability as well as NDRG2 and NIS gen expressions in 8505C cells with different incubatoin time. Material and Methods: This study was carried out on Nthy-ori-3-1, normal human thyroid follicular epithelial cells and 8505C, undifferentiated human anaplastic thyroid carcinoma cell line. The basal expression levels of NDRG2 and NIS on both cell lines were investigated with RT-PCR. The effect of calcitriol on cell viability was evaluated with WST-1 test. The changes in NDRG2 and NIS gene expressions in calcitriol treated 8505C cells were also investigated with Real-Time Polimerase Chain Reaction. Results: NDRG2 and NIS gene expressions were found significantly higher in Nthy-ori-3-1 cells compared with 8505C cells. According to WST-1 test results, the incubation of 8505C cells with 60 µM calcitriol by 24 - 48 and 72 hours resulted in 62% - 63% and 56% decrease in cell viability, respectively. No significant differences were found in NDRG2 and NIS gene expressions between control group without calcitriol and 8505C cells which were incubated with 60 µM calcitriol by 24 and 48 hours. Conclusions: NDRG2 and NIS gene expressions were found significantly higher in Nthy-ori-3-1 cells compared to 8505C cells. However, it was shown that calcitriol didn?t lead to any differences on NDRG2 and NIS gene expressions in 8505C cells. Keywords: Anaplastic thyroid cancer, 1-25dihyroxivitamin D3, N-myc Dowstream Regulated Gene-2, Sodium-Iodide Symporter