Effects Of STEAP1 On The Invasion And Metastasis Of Breast Cancer

BackgroundBreast cancer is one of the most common malignancies leading to female mortality.Current study of biomarkers and immunological therapy have been developed,and the signature in the process of breast cancer growth and metastasis,tumor gene transfer to develop a treatment for recurrent breast cancer patient strategy is particularly important.STEAP1(ix-transmembrane epithelial antigen of the prostate)was first found in prostate cancer,as a cell surface antigen,mainly locate on the cell membrane,in cells or cell adhesion as ion channels and transporters involved in cell comunication.Based on STEAP1 as targets of antibody immunotherapy has been used in the treatment of prostate cancer,research on relationship between breast cancer and STEAP1,domestic has not been developed,and the foreign research conclusion are different.EMT(Epithelial mesenchymal transition)play an important role in cancer invasion and metastasis.In the process of EMT progress,cytoskeleton and shape change,the adhesion effect between epithelial cells and polarity disappeared,cell movement ability increases,the morphology and properties of mesenchymal cells,so as to improve the ability of cell migration,invasion.Studies on EMT biomarkers have been widely carried out,such as cytoskeletal proteins and related transcription factors.STEAP1 participates in cell connections and cell communication,and may have some correlation with the EMT process.By researching the relationship between STEAP1 expression and EMT markers,it can explore the role of STEAP1 in the EMT process.Objective1.Explore the expression of STEAP1 in breast cancer and its clinical significance.2.Explore the effect of enhancement or reduction of STEAP1 expression on the migration,invasion and proliferation of breast cancer cells and breast epithelial cells.3.Explore the mechanism of STEAP1 affecting the progression of breast cancer..Methods1.Immunohistochemical method(IHC)was used to detect the expression of STEAP1 in normal tissue,fibroadenoma and carcinoma tissues of the breast;2.Reverse transcription-quantitative polymerization chain reaction(RT-qPCR),immunocytochemistry(ICC),and western blot to detect the expression of STEAP1 in breast epithelial cells and breast cancer cells;3.Using public database Oncomine and Kaplan-meier plotter to explore the expression of STEAP1 in breast cancer and its relationship with prognosis;4.Build slow virus carrier for transfection,enhance STEAP1 in MCF-7(breast cancer cells),using RNA interference to reduce STEAPlin HBL-100(mammary epithelial cells),and by RT-qPCR,Western blot test the transfection efficiency;5.Transwell,cell growth curve and flow cytometry were used to detect the movement and proliferation after change the STEAP1 expression in breast cancer cells and breast epithelial cells;6.Using RT-qPCR to detect the expression of EMT related markers in breast cells.Results1.The immunohistochemical results showed that STEAP1 expression in normal breast tissue and fibroadenoma were significantly higher than breast cancer tissue,and associated with lymph node metastasis,differentiation degree and the histologic grading,and higher expression of STEAP1 tended to have longer survival time;2.RT-qPCR,ICC and Western blot showed that the expression of STEAP1 mRNA and protein were significantly higher in breast epithelial cells than breast cancer cell lines(BT549,MDA-MB-468 and MCF-7);3.The analysis of public database showed that the expression level of STEAP1mRNA in breast cancer was significantly lower than that of normal tissue,and the expression of STEAP1 was related to a better survival;4.Under fluorescence microscope,slow virus transfection efficiency was more than 80%,which was verified by RT-qPCR and Western blot;5.After the slow virus mediated STEAP1 expression,breast cancer cell migration and invasion ability were reduced,and there was no significant change in proliferation ability.After RNA interference reduced the expression of STEAP1,the migration and invasion ability of mammary epithelial cells were enhanced,and there was no significant change in proliferation ability.6.After the enhanced the expression of STEAP1 in breast cancer cells,the expression of MMP2,MMP9,MMP13,VIM and CDH2 were decreased,and the expression of CDH1 increased,which mean that EMT process was inhibited.At the meantime,after reduced the expression of STEAP1 in the breast epithelial cells,the expression of MMP2;MMP9,MMP13,VIM and CDH2 were increased,and the expression of CDH1 decreased,which mean promoting the progress of EMT.Conclusion1.The expression level of STEAP1 in breast cancer is lower than normal tissue,which suggestes that STEAP1 may act as a tumor suppressor factor in breast cancer.2.The expression of STEAP1 can inhibit the invasion and metastasis of breast cancer cells.3.The mechanism of STEAP1 inbreast cancer is related to EMT,and its expression can inhibit the progress of EMT.