Abstract: Objective To investigate the effect of 17β-estradiol on the expression of Hsp27 in papillary thyroid cancer BCPAP cells and its mechanism . Methods BCPAP cells were treated with 10-8 mol/L 17β-estradiol (E2) for different time periods , the expression of Hsp27 protein in cells was detected by Western blot; BCPAP cells were treated with E2, PPT and DPN, then detected the levels of Hsp27 byWestern blot ; RNA interference against ERα ( ERα siRNA ) and ERβ (ERβ siRNA ) was designed and synthesized, then transfected to BCPAP cells.The expression levels of Hsp27, ERα and ERβ in cells was analyzed by Western blot. The activity of Hsp27promoter was evaluated by chromatin immunoprecipitation analysis(CHIP). Results BCPAP cells were treated with 10-8 mol/L E2 for different time periods , the expression level of Hsp27 in BCPAP cells was increased gradually with the increasing hours for E2 treatment, and peaked at 24 h (P<0.05). Pretreatment with ERα siRNA obliterated the inductive effects of E2 on Hsp27 protein expression levels (P<0.05), but pretreatment with ERβ siRNA increased the inductive effects of E2 on Hsp27 protein expression levels in BCPAP cells (P<0.05). ChIP result has confirmed that ERα protein could bind to the region of Hsp27 gene promoter in BCPAP cells.Conclusion E2 can induced the the expression of Hsp27 in BCPAP cells by a ERα-dependent manner.

Key words: 17β-estradiol, Hsp27, estrogen receptor, papillary thyroid cancer