The Impact Of Tamoxifen On Estrogen Receptor-positive Papillary Thyroid Carcinoma Cyclind <sub> 1 </ Sub>

OBJECTIVE: To explore the effect of tamoxifen (TAM) on the cell cycle regulatory proteins (CyclinD1) expression of estrogen receptor (ER)-positive papillary thyroid carcinoma (Papillary Thyroid Carcinoma PTC) cells ,and a preliminary study of its mechanism, and investigate its role in proliferation of papillary thyroid cancer cells.METHODS: The Primary cultured papillary thyroid cancer, were incubated with 10-8mol/Lβ-estrodiol and 10-8mol/L TAM, for 1,3,5,7days and were harvested respectively. The applications of RT-PCR and Western-blot detect the effect ofβ-estradiol and TAM on CyclinDl in papillary thyroid cancer cells in vitro.RESULT:β-estradiol increased the expression of CyclinD1 in papillary thyroid cancer cells (P <0.05), TAM weakend the effect by reduced the expression of CyclinD1 (P <0.05);withβ-estradiol and TAM stimulated the ER-positive papillary thyroid cancer cells, RT-PCR and Western-bolt showed the increased expression of CyclinDl, the optical density analyzer analyzed CyclinD1 andβ-actin optical density of estradiol group ,the expression of CyclinD1 was higher than the control group (P <0.05), and increased markedly at 8h, then changed slightly, the expression of CyclinD1 in estradiol + TAM group decreased from 4h compaired with estradiol group, the optical density analyzer analyzed the CyclinD1 andβ-actin optical density of estradiol + TAM group, the expression of CyclinD1 decreased compared with the estradiol group (P <0.05). These results suggested that the expression of CyclinD1 of estradiol group were significantly higher than the control group and closer to the peak at about 8h, the expression at 8h and 12h increased significantly than 2h and 4h, 8h group compared with 12h group had no significant differences; through the group comparison we found that TAM could weaken the expression of CyclinD1 which increased byβ-estrodiol at 4h in papillary thyroid cancer cells.CONCLUSION:β-estradiol could increase the expression of CyclinD1 in papillary thyroid cancer cells (P <0.05), TAM could reduce the expression. Further that TAM may inhibit the growth of ER-positive papillary thyroid cancer cell.