Biological Function Analysis And Target Gene Validation Of MiR-181c In Breast Cancer

Purpose To explore the level and the potential function of microRNA-181c-5p(miR-181c)in breast cancer.Methods The miR-181c expression in breast cancer cell lines and tissues was measured by quantitative reverse transcription-polymerase chain reaction(qRT-PCR)assays.The MTT assay,plate colony formation assay,wound healing assay,transwell assay,western blot assay and flow cytometry analyses were used to characterize the function of miR-181c in two kinds of breast cancer cell lines.The dual-luciferase reporter assay was used to confirm the direct combination between miR-181c and mitogen-activated protein kinase kinase kinase kinase 4(MAP4K4).The expression levels and the role of endogenous MAP4K4 in breast cancer were also determined by using the above methods.Results The miR-181c was reduced in human breast cancer cell lines and specimens.Up-regulation of miR-181c inhibited cellular proliferation,invasion,migration and regulated the cell cycle by arresting cells in the G0/G1 cell phase.MiR-181c negatively regulated MAP4K4 mRNA and protein levels,and MAP4K4 was a direct target.Silencing of MAP4K4 expression by siRNA-MAP4K4(siR-MAP4K4)also significantly suppressed cell proliferation,invasion,migration and arrested cells in the G0/G1 cell phase.Conclusion MiR-181c acted as a tumor suppressor and played a crucial part in repressing the tumorigenesis by targeting MAP4K4 in breast cancer cells.