The Experimental Study Of Estrogen Affects On Colorectal Cancer Cell Proliferation And Apoptosis

ObjectiveTo investigate the expression of ERa, ERβand GPR30 in colon cancer cell line and analyze their different functions in cell proliferation induced by 17β-estradiol, and focus on the expression features of ERa and ERβ.MethodsThe expression of ERa, ERβand GPR30 mRNA in MCA-38 cell line were measured by RT-PCR, and the expression of ERa, ERP and GPR30 protein were measured by Western Blot. After being incubated with the different concentrations of E2 and E2-BSA (0, 0.01nM, 0.1nM, 1nM, 10nM,100nM, respectively) for 24 hours, the MCA-38 cell proliferation was assessed by MTT assay. The expression of ERα, ERβand caspase-3 proteins were detected by Western blot.Results(1) ERα, ERβand GPR30 were expressed in MCA-38 cell line both at mRNA and protein levels, and the ERβexpression was the highest one. (2) Physiological doses of E2 (0.1nM-10nM) significantly promoted MCA-38 cell proliferation, and the number of the tumor cells increased by 20.47%,25.29%,37.59% and 30.95%(P <0.05), while E2-BSA did not shown effects on cell proliferation compared with control group. (3) Western blot showed that both ERa and ERβwere expressed in MCA-38 cell line with ERP dominated. After incubation with different concentration of E2 for 24 hours and compared with the control group, the expression of ERa protein was upregulated while the ERP was decreased. 0.01nM, 0.1nM and 1nM of E2 elevated ERa level by 4.7%,5.5% and 5.9%(P<0.05), and 0.1nM, 1nM of E2 lowered ERβexpression by 10.2% and 3.9% (P<0.05). 0.1nM, 1nM of E2 decreased caspase-3 protein by 20.2% and 32.9%(P<0.05).Conclusion(1) Physiological doses of E2 significantly affected the cell proliferation of MCA-38 cell line, and the promoting cell proliferation effect of E2 on MCA-38 cell line was likely mediate by the signal transduction pathways of the estrogen nuclear receptor without participation of the estrogen membrane receptor.(2) 17β-estradiol affected the cell proliferation and apoptosis of MCA-38 cell line. The tumor cell proliferation was associated with the increased expression of ERa, and the change of cell apoptosis was closely related with ERβexpression.