MicroRNAs Expression Profile In Human Breast Cancer MCF-7 Cells Of Different HER-2 Levels And Effect Of MicroRNAs On Tumor Cell Biological Behavior

Background: Human epidermalgrowth factor receptor-2(HER-2) is a membrane tyrosine kinase and a member of the epidermal growth factor receptor family. When activated it provides the cell with potent proliferative and antiapoptosis signals and it is the major driver of tumor development and progression in breast cancer. Micro RNAs(mi RNAs) are a class of small(18–25 nucleotides), endogenous, noncoding, single-stranded RNAs. mi RNAs regulate major cellular processes involved in tumor biology, including cell proliferation, differentiation, apoptosis, and metastasis. Further, some mi RNAs can serve as either oncogenes or oncosuppressors in the regulation of cells. In recent years, the reports about the differences between HER-2 and mi RNAs were increasing. Some studies suggested that the development of breast cancer were associated with the overexpression of HER-2 and the disorder of mi RNAs. So to explore the links between mi RNAs and HER-2 are extremely very important.Objective: To filter out the mi RNAs expression profile related to HER-2 gene via observation on mi RNAs expression by human breast cancer cell lines MCF-7 and MCF-7 stably transfected with HER-2(MCF-7/HER-2). It could provide bases through mi RNAs participated in HER-2 signaling pathway and participated in regulation of breast cancer cells in biological behavior mechanism.Methods:(1) The expression profile of mi RNAs in cells were detected by mi RNAs microarrays by cultivating human breast cancer MCF-7 cells and MCF-7/HER-2 cells. The standard was that the differential expression of mi RNAs between human breast cancer MCF-7 cells and MCF-7/HER-2 cells which the Fold Change>2.0 would screen out.(2) Compared with MCF-7 cells, pick out the significantly up-regulated hsa-mi R-181a-5p and down-regulated hsa-mi R-877-3p, then q RT-PCR experiments were used to verify the expression levels of hsa-mi R-181a-5p and hsa-mi R-877-3p in MCF-7 cells and MCF-7/HER-2 cells.(3) The hsa-mi R-181a-5p ASO or hsa-mi R-877-3p mimic was transfect into MCF-7/HER-2 cells and the biological functions of cells were detected by wound-healing assay, cell proliferation assay and cell migration and invasion assay.(4) The possible target genes of hsa-mi R-181a-5p or hsa-mi R-877-3p were forecasted by bioinformatics methods.Results:(1) Two hundred and seventeen mi RNAs related with HER-2 gene were identified from human breast cancer cell lines MCF-7 and MCF-7/HER-2, compared to MCF-7 cells, including one hundred and twenty three up-regulated mi RNAs and ninety four down-regulated mi RNAs.(2) Compared with MCF-7 cells, the results of q RT-PCR showed that the expression levels of hsa-mi R-181a-5p in MCF-7/HER-2 cells were up-regulated and the hsa-mi R-877-3p in MCF-7/HER-2 cells were down-regulated(P<0.01).(3) hsa-mi R-181a-5p had a promoting effect on cells proliferation, invasion and migration in HER-2-positive breast cancer and hsa-mi R-877-3p had an inhibitory activity on cells proliferation, invasion and migration in HER-2-positive breast cancer.Conclusion:(1) The expression profiles of mi RNAs relative to MCF-7 cells and MCF-7/HER-2 cells were obtained.(2) Compared with MCF-7 cells, the expression levels of hsa-mi R-181a-5p in MCF-7/HER-2 cells were up-regulated. In HER-2-positive breast cancer cells hsa-mi R-181a-5p may promote cell proliferation, invasion and migration.(3) Compared with MCF-7 cells, the expression levels of hsa-mi R-877-3p in MCF-7/HER-2 cells were down-regulated. In HER-2-positive breast cancer cells hsa-mi R-877-3p may inhibit cell proliferation, invasion and migration.