Objective   To investigate the

effect of G-protein coupled receptor (GPER) on 17β-Estradiol (E2) induced proliferation of human anaplastic thyroid carcinoma FRO cells.    Methods   FRO cells were treated with different concentration (0，10

-10

，10

-9

and 10

-8

mol/L) of E2 for different time periods (0，12 and 24 h)

and cell growth was evaluated by MTT assay. After the cells were treated by 10

-8

mol/L E2 for different time periods (0

12 and 24 h)

cell cycle was analyzed by flow cytometry. RNA interference against GPER (GPER-RNAi) was designed and synthesized

then transfected to FRO cells. The levels of phosphorylated ERK1/2

phosphorylated Akt and GPER were analyzed by Western blot analysis.    Results   Treatment with different concentration (0

10

-10

10

-9

and 10

-8

mol/L) of E2 for different times (0

12 and 24 h)

the cell growth rates were increased in dose- and time-dependent manners. When FRO cells were treated with 10

-8

mol/L E2 for 24 h

the cell growth rate was (16.5±2.1) %. After the cells were treated with 10

-8

mol/L E2 for different times (0

12 and 24 h)

the percentages of S/G

2

/M phase were increased in a time-dependent manner. E2-induced accumulation of phosphorylated ERK1/2 and phosphorylated Akt in FRO cells reached peak at 15 min and 10 min respectively after E2 treatment. The expression of GPER was reduced significantly when GPER-siRNA was transfected to FRO cells for 48 h. Pretreatment with PD98059 (30 μmol/L)

LY294002 (50 μmol/L) and GPER-siRNA obliterated the inductive effects of E2 on ERK1/2 phosphorylation and Akt phosphorylation at 15 min and 10 min respectively in FRO cells. Meanwhile pretreatment with PD98059

LY294002 and GPER-siRNA obliterated the inductive effects of E2 on cell growth. and the growth rates were reduced to (11.2±1.3)%

(9.6±1.5)% and (7.2±1.3)% respectively compared with those of E2-treated cells [(16.5±2.1)%

P0.05

]

.    Conclusion   E2 can promote proliferation of FRO cells via ERK1/2 and PI3K-A

kt pathway in a GPER-dependent manner.