Expression And Roles Of ARHGDIB In Breast Cancer

Background Breast cancer is one of the most common malignancy in women,which endangers women's health and life seriously.As a result of the increasing longevity,increased urbanization and the adoption of western lifestyles,the incidence of breast cancer is increasing in the developing world.According to the 2019 National Cancer Surveillance Report published by the American Cancer Society's journal CA Cancer J Clin in 2019,breast cancer ranks second,accounting for 15% of the tumors that cause death among women in the United States.ARHGDIB is one of the key regulators of Rho GTPase and plays an important role in the development of migration,invasion,and multi-drug resistance for tumor cells.The metastasis and resistance during the progress of treatment are the main reasons for poor prognosis in breast cancer patients.To clarify the regulatory genes about tumor metastasis and resistance will help to provide new ideas for the treatment of breast cancer.Aim To observe the expression of ARHGDIB in breast tissues,common breast cell lines and the adriamycin-resistant cell line;To explore the effect of ARHGDIB on the clone formation,cell cycle,migration,invasion and adriamycin-resistant in breast cancer cells.Methods 1)Immunohistochemistry(IHC)was used to detect the expression of ARHGDIB in 100 breast cancer samples and 100 benign breast disease samples.2)Western blot was used to detect the expression of ARHGDIB in the normal breast epithelial cell line,breast cancer cell lines and the adriamycin-resistant cell line.3)The expression of ARHGDIB protein was higher in MDA-MB-231 and MCF-7/ADR cells.The si RNA targeting the ARHGDIB(si AR)or NC(negative control)were transfected into MDA-MB-231 and MCF-7/ADR cells to interfere its expression.RTq PCR analysis and western blot were used to confirm the efficiency of si RNA transfection.4)The effect of interfering ARHGDIB expression on colony formation in MDA-MB-231 cells was detected by colony formation assay.5)The effect of interfering ARHGDIB expression on cell cycle in MDA-MB-231 cells was detected by cell cycle experiments.6)The effect of interfering ARHGDIB expression on migration and invasion in MDAMB-231 cells was detected by transwell assay.7)The effect of interfering ARHGDIB expression on EMT markers including ?-catenin and MMP2 in MDA-MB-231 cells was detected by western blot.8)The effect of interfering ARHGDIB expression on adriamycin-resistant in MCF-7/ADR cells was detected by MTT assay.Results 1)IHC showed that the expression of ARHGDIB is localized in the cytoplasm of mammary epithelial cells and cancer cells.Compared with benign breast disease samples 39.0 %(39/100)high expression rates,ARHGDIB was upregulated in breast cancer tissues with 74.0 %(74/100)high expression rates(P<0.01).2)Western blot showed that the expression ARHGDIB in breast cancer cell lines was higher,especially in the highly aggressive breast cancer cell line MDA-MB-231;The expression of ARHGDIB in MCF7/ADR was higher than that of its parental cell MCF-7.3)The results of q PCR and western blot showed that the levels of m RNA and protein expression were significantly decreased in MDA-MB-231 and MCF7/ADR cells after transfection of si AR(P<0.01).4)The colony formation assay showed that the ability of clone formation of si AR group was significantly inhibited in MDA-MB-231 cells(P < 0.01).5)The cell cycle experiments showed that the population of both si AR-transfected MDA-MB-231 cells in the G0/G1 phase increased significantly.(P < 0.01).6)The results of migration and invasion assay showed that the migration and invasion ability of the si AR group were significantly decreased compared with the control group(all P<0.01).7)Western blot showed that the protein levels of epithelial marker ?-catenin were increased while mesenchymal markers MMP2 were decreased significantly after transfection with si AR.8)MTT assay showed that the adriamycin-resistant were inhibited significantly after transfection with si AR in MCF-7/ADR.Conclusion ARHGDIB may promote the development and adriamycin-resistant of breast cancer by regulating the expression level of EMT-related proteins in breast cancer.It may be a potential target for diagnosis and treatment of breast cancer.