Role of extracellular signal-regulated protein kinase in estrogen-induced proliferation of breast cancer cell line MCF-7 / 第二军医大学学报

ABSTRACT

Objective: To investigate the role of extracellular signal-regulated protein kinase (ERK) in estrogen-induced proliferation and cell cycle transformation of breast cancer cell line MCF-7 and the related mechanisms. Methods: Estrogen receptor-positive breast cancer cell line MCF-7 was used in our study. The effects of 17β-E2 on the proliferation of MCF-7 cells was investigated by MTT assay to determine the optimal concentration of 17β-E2 for the following experiment. The effect of PD98059 on 17β-E2-induced proliferation of MCF-7 cells was measured by MTT assay to determine the intermediate concentration of PD98059. The cell cycle was analyzed by flow cytometry and telomerase activity was determined by Telomerase repeat amplification protocol PCR (TRAP-PCR) silver staining. The expression of wild-type p53 and phosphorylated ERK1/2 protein was determined by Western blotting and the expression of wild-type p53 mRNA was detected by RT-PCR. Results: ERK phosphorylation inhibitor PD98059 inhibited the proliferation of MCF-7 cells treated with 17β-E2 in a time- and dose-dependent manner(P<0.01). The intermediate concentrations of PD98059 were 89.28 μmol/L for 24 h, 39.81 μmol/L for 48 h and 21.87 μmol/L for 72 h. Treatment with 20 μmol/L PD98059 for 48 h reversed the promoting effect of 17β-estradiol on the cell cycle transformation of MCF-7, increasing the number of G1 phase cells and decreasing the number of S and M phase cells (P<0.01), inhibited the enhancing effect of 17β-E2 on the telomerase activity of MCF-7 cells(P<0.05), increased the protein expression level and genetic transcription of wild-type p53 (P<0.01), and decreased the expression of p-ERK1/2 protein(P <0.01). Conclusion: ERK plays an important role in 17β-E2-induced proliferation and cell cycle transformation of breast cancer cell line MCF-7, which might be related to the changes of genetic transcription of wild type p53 and telomerase activity.