Secreted and Cellular Polypeptide Patterns of MCF-7 Human Breast Cancer Cells following either Estrogen Stimulation or v-U-ras Transfection

The polypeptide patterns of MCF-7 human breast cancer cells (MCF7gpt) and a stably v-H-roi-transfected subclone (MCF-7ras) have been analyzed following estradili! treatment. Since both estradili! and \-H-ras transfection increase tumorigenicity of MCF-7 cells, this study was designed to ascertain if specific changes in polypeptides were common in both treatments. Separation of cellular and secreted polypeptides was accomplished by 2-dimensional polyacrylamide gel electrophoresis, and the consequent patterns were analyzed with computer assistance. I stra dini treatment of the MCF-7gpt cells reduced the number of differences found in the polypeptide patterns between MCF-7gpt and MCF-7ras. Twelve cellular polypeptides were consistently modulated by either estradiol or v-I I-rav, with four polypeptides clearly affected in the same way by both treatments. Polypeptides Gchc-0845 (M, 54,000, pi 6.9) and Gchc-0902 (M, 52,000, pi 6.3) were suppressed by estraditi! and v-Hras, while Gchc-1240 (M, 34,000, pi 4.4) and Gchc-1396 (M, 23,000, pi 5.3) were induced by estradiol and v-I I-rav. Sixteen secreted polypeptides were altered by at least 2-fold subsequent to estradiol treatment or v-Hru.Ytransfection. Transfection with v-I I-rav had a greater effect than estradiol, stimulating the secretion of eight polypeptides and suppressing the secretion of seven polypeptides compared to estradiol which increased secretion of five polypeptides and decreased secretion of an additional three polypeptides, respectively. Synergistic effects by estradiol and vH-ras were noted for three polypeptides. The secretion of Gcls-175 (M, 50,000, pi 5.7) and Gcls-320 (M, < 14,000, pi 3.6, p-S2) was increased, while the secretion of Gcls-112 (M, 76,000, pi 6.9) was decreased. Opposing effects of estradiol and v-I l-ra.v were seen for seven polypep tides including the M, 48,000 derivative of the M, 52,000 protein (cathepsin D). These studies support the possibility that an extremely few, but specific polypeptides are regulated in association with quite diverse tumorigenic stimuli in MCF-7 human breast cancer cells.