Effect of estrogen on telomerase activity in human breast cancer cells

Summary

To investigate the effects of estrogen (E₂) on telomerase activity and its mechanism in human breast cancer cells, estrogen receptor positive MCF-7 cells were treated with different concentrations of E₂. Telomerase activity was measured by using TRAP-ELISA method, the cell cycle phases analyzed by using flow cytometry, and the expression of Cyclin D₁ detected by using immunohistochemistry method. The results showed that telomerase activity levels were increased in MCF-7 cells treated with 10⁻⁸ mol/L E₂ during the observed period (P<0.05), and E₂ increased telomerase activity levels in a dose-dependent manner (10⁻¹⁰-10⁻⁸ mol/L); Simultaneously, the cell cycle phases of MCF-7 cells treated with 10⁻⁸ mol/L E₂ were changed significantly: G₀/G₁ phase decreased from 60.52% to 50.93%, S phase increased from 29.03% to 30.83%; However, the expression of Cyclin D₁ was decreased. It was concluded that estrogen can upregulate telomerase activity of MCF-7 cells, and the effect can be blocked by antiestrogen tamoxifen. Its mechanism may be closely associated with modulation of cell cycle phases.