The Biological Effects Of Tumor Differentiation Factor (TDF) On Human Breast Cancer Cells

Objective:Breast cancer is one of the most common malignant tumors of women, and the morbidity has increased steadily, which is a big threaten to women’s life and healt-h. The pathogenesis of breast cancer is not completely clear, and effective prevention of it is still vacant. Now, the mainstream treatment of breast cancer including:operation, chemotherapy, radiotherapy, targeted therapy and endocrine therapy, but breast cancer is still one of the tumors with the highest mortality of women, to seek a effective treatment is always the research focus of breast cancer. In recent years, Researchers discovered a108-amino-acid polypeptide that had differentiation activity on MCF-7breast cancer cells and on DU145prostate cancer cells in vitro and in vivo, named tumor differentiation factor (TDF). TDF is an underinvestigated protein produced by the pituitary with no definitive function. For identify TDF receptor candidate They used AP and LC-MS/MS experiments.They identified four proteins with high confidence: glucose-regulated protein:GRP78, heat shock protein8(HSP8), heat shock protein1(HSP1), heat shock protein A9(HSPA9). HSP8, HSP1, HSPA9were all part of the HSP70protein family. So the highest probability to be the potential TDF receptor was glucoseregulated protein (GRP78) and heat shock70-kDa protein, Our paper research the expression of TDF receptor in tissues and cells and the biological effects of its functional fragment TDF-P1on human breast cancer cells, to explore the possible mechanism for the induced differentiation mechanism of TDF.Methods:1. Immunohistochemical methods was used to investigate the expression of TDF receptors:heat shock protein receptor70(HSP70) and glucose-regulated protein78(GRP78) in different tissues. Western blotting was used to investigate the expression of TDF receptors in different cells;2.3(4,5-Dimethy-lthiazol-2-yl)-2,5-diphenyltetrazo-lium bromide(MTT) was used to investigate the proliferation of MCF-7cells treated with different concentrations of TDF-P1. The cell cycle distribution of MCF-7was exami-ned by flow cytometry after coculture with TDF-P1. Then used trans well to detect cell invasion and migration ability.Results:1. GRP78protein expression in breast cancer tissue is slightly higher than in other tissues, in normal breast tissue was significantly higher than in other normal tissues. The HSP70protein expression was no significant difference between those groups. The expression in cancer tissue is much higher than in normal tissue. GRP78protein expressed in MCF-7cells and MDA-MB-231is higher than the other groups, and MCF-7cells expressed more obviously. The expression of HSP70was no significant difference between the cell lines.2. TDF-P1inhibited the growth of MCF-7cells in a concentration-dependent manner. Flow cotometry analysis revealed a significant increased concentration dependen-t accumulation of MCF-7cells in the G0/G1phase(77.2±2.63)%and the difference is stat-istically significant campared with normal control group (47.56±1.23)%. TDF-P1inhibi-ted the migration cell numbers of MCF-7cells, the migration cell numbers of MCF-7were (112±9) vs(423±28),(P<0.01). TDF-P1inhibited the invasion cell numbers of MCF-7cells, the invasion cell numbers of MCF-7were (20±5) vs(126±11),(P<0.01).Conclusion:1. The expression of GRP78and HSP70in cancer tissues was more than in normal tissue. GRP78protein expression in breast cancer tissue is slightly higher than in other tissues, in normal breast tissue was significantly higher than in other normal tissues.2. TDF can induce colony-like growth in MCF-7breast cancer cells. TDF-P1can inhibit the proliferation, migration, invasion of MCF-7cells, and arrest cells cycle in the G0/G1.