Study On The Effects Of 17-β Estradiol And Serum On Protein Expression In MCF-7 Breast Cancer Cells

Estrogen, hormones and growth factors in serum play important roles in the carcinogenesis and development of breast cancer. To study the effects of the above factors on protein components and their content in breast cancer cells is necessary for understanding the underlying molecular mechanisms. Tamoxifen (TAM) is a drug widely used in the treatment of estrogen-responsive breast cancer. To study the effect of TAM on protein expression in breast cancer cells is helpful for understanding the molecular mechanisms of its role in growth inhibition. In this study, iTRAQ labeling combined with 2DLC-MS/MS was employed to study the effects of 17-βestradiol (E2), serum starvation (SD), TAM and combination of E2+SD, E2+TAM on the expression of different proteins in MCF7 cells.In E2 and SD treatment experiment, using Q-TOF analysis, 94 proteins were found to be differentially expressed by 1.5 fold. E2 upregulated 21 and downregulated 16 proteins in serum containing media, SD upregulated 10 and downregulated 27 proteins and E2 upregulated 19 and downregulated 22 proteins in SD medium as compared with MCF7 cells cultured with E2 depleted media. In E2 and TAM treatment experiment, using MALDI-TOF-TOF analysis, 47 proteins were shown to be differentially expressed by 1.5 fold. E2 upregulated and downregulated 16 and 22 proteins, TAM upregulated 4 and downregulated 8 proteins while E2+TAM treatment upregulated 6 and downregulated 1 protein as compared with MCF7 cells cultured with E2 depleted media.Comparison of proteins differentially expressed after E2 treatment observed using ESI-Q-TOF and MALDI-TOF-TOF. It is found that these two kinds of instruments are complementary both in protein identification and quantification. The combined use of ESI-Q-TOF and MALDI-TOF-TOF significantly increase the coverage of analyzed proteome and the confidence level of proteins identified and/or quantified by both instruments.