The effect of miR-20b on breast cancer cell proliferation and related mechanism

Abstract Background and Purpose Breast cancer is the the most common malignant tumor of women, and contributes to the main cause of death of female malignant tumors. Although there are many mutated oncogenes and anti-oncogenes during the course of breast cancer formation, it is not clear that the specific molecular mechanism to maintain the malignant proliferation of tumor cells. Studies have shown that microRNAs (miRNAs) display specific expression in different tumor tissues and play an important role in the development of tumors. The purpose of this paper is to explore the influences of miR-20b on the breast cancer cell proliferation and the regulation function of miR-20b to the targeted genes.It will provide evidence for diagnosis and treatment of breast cancer and lay a foundation for its clinical targeted diagnosis and treatment. Methods We analyzed the expressive levels of miR-20b within cancer tissue and corresponding normal tissue adjacent to carcinoma of 10 breast cancer patients, as well as the normal breast epithelial cell lines MCF-10A and SKBR3, MCF-7, and MDA-MB-231 breast cancer cell lines through quantitative PCR (qPCR). MDA-MB-231 breast cancer cell line was up-regulated by miR-20b, and the effect of miR-20b on proliferation ability of breast cancer cells were detected by MTT and colony formation assay. The effect of miR-20b on the tumor formation ability of 231 breast cancer cells was detected by the breast cancer model of BALB/c mice. we used the bioinformatics to predict the possible downstream target genes, and verified it through luciferase experiment. Finally, the regulation effect of miR-20b on target genes was detected by qPCR and western blot in mRNA and protein levels. Results The present study confirmed that the expressive level of miR-20b were significantly reduced in breast cancer tissue and cells. MTT and colony formation data showed that miR-20b inhibited the proliferation ability of 231 breast cancer cells, and the breast cancer model of BALB/c nude mice showed that miR-20b inhibited the tumor formation ability of 231 breast cancer cells. The luciferase experiment confirmed that hypoxia inducible factor-α(HIF-α)was a potential downstream target gene of miR-20b. Finally we found by qPCR and western blot that miR-20b could inhibit the expression of target gene HIF-α in mRNA and protein levels. Conclusions MiR-20b can inhibit the proliferation of breast cancer cells. MiR-20b can inhibit the expression of target gene HIF-α in mRNA and protein levels.