Objective To investigate whether 17β-estradiol (E2) can stimulate the proliferation,migration,and secretion of trefoil factor family 1 (TFF1) in papillary thyroid cancer K-1 cells and explore the molecular mechanisms.Methods ELISA was used to detect the content of TFF1 in the supernatant of K-1 cells after the treatment of E2,propylpyrazoletriol (PPT,ERα agonist) or diarylpropionitrile (DPN,ERβ agonist).The expression of ERα and ERβ in the untreated cells was measured by Western blotting.ERα siRNA and ERβ siRNA by RNA interference were designed and synthesized,and the change of TFF1 was measured by ELISA again after the transfection.The interaction between TFF1 promoter and ER was evaluated by chromatin immunoprecipitation analysis (CHiP).The proliferation and migration were detected in the K-1 cells after E2 treatment by MTT assay and Transwell chamber test respectively.Festults After E2 treatment,the TFF1 content in the supernatant of K-1 cells was increased gradually,reached peak at 24 h,and then declined slowly.PPT treatment enhanced the secretion of TFF1 but DPN decreased it in the K-1 cells.Transfection of ERα siRNA obliterated the inductive effect of E2 on the secretion of TFF1,but that of ERβ siRNA increased the inductive effect in the K-1 cells.Western blotting showed that the expression level of ERα was higher than that of ERβ in the K-1 cells.ChIP results confirmed that ERα protein was bound to the promoter of TFF1 gene in K-1 cells.E2 treatment promoted cell proliferation and improved cell migration in the K-1 cells.Conclusion E2 induces the expression and secretion of TFF1 in K-1 cells through ERα-dependent manner,and thus promotes the proliferation and migration of the cells.