MiRNA-139-5p Modulates Chemosensitivity And Migration Of Breast Cancer Cells By Targeting ZEB1

Objectives:In the world, breast cancer is the most common malignancy, and is the primary cause of cancer death for woman. MiRNA-139-5p has been shown to inhibit metastasis of breast cancer cells, and the molecular mechnisms under which worth exploration. Further, the role of miRNA-139-5p in chemosensitivity of breast cancer remains unknown. The aim of this study is to investigate the role of miRNA-139-5p in chemosensitivity and migration of breast cancer cells, and to explore the molecular mechanisms behind it.Methods:RT-PCR was used to measure miRNA-139-5p and ZEBl mRNA in breast cancer cell lines MCF-7, MCF-7/Doc and MDA-MB-231, while western blot assay was used to detect the expression of ZEB1. MiRNA-139-5p mimic was transfected to upregulate miRNA-139-5p. CCK-8 assay was used to test cancer cell response to docetaxel, while transwell assay and wound healing test were performed to observe cancer cell migration before and after transfection. By RT-PCR and Western Blot, the impact of miRNA-139-5p on the expression of ZEB1 was studied. RT-PCR was used to explore the expression of miRNA-139-5p and ZEB1 mRNA in cancer tissues and paired adjacent normal tissues, the relationship between them was analyzed. Furthermore, the relevance of miRNA-139-5p and ZEB1 in response to neoadjuvant chemotherapy containing docetaxel was also studied. The relationship between miRNA-139-5p and clinicopathological parameters and overall survival was analyzed using data from TCGA. Statistical analysis:the results were analyzed by SPSS 19.0 software statistics. The experiment were repeated independently for at least three times. Data was show as mean±standard deviation, variance between groups were tested by t test or nonparametric test according to different distribution. p<0.05 was considered statistically significant.Results:The expression of miRNA-139-5p was higher in both MCF-7/Doc and MDA-MB-231 cells than in MCF-7 cells, while ZEB1 expression was opposite to that. Upregulation of miRNA-139-5p by transfection improved chemosensitivity of MCF-7 and MCF-7/Doc cells to docetaxel and inhibited migration of MCF-7 and MDA-MB-231 cells. The expression of ZEB1 in MCF-7 cells was inversely changed after upregulation or downregulation of miRNA-139-5p. Chemosensitivity of MCF-7 cells to docetaxel was enhanced after knockdown of ZEB1, while migration was inhibited. Knockdown of ZEB1 reversed the impact of miRNA-139-5p inhibitor on chemosensitivity and migration of MCF-7cells. Both miRNA-139-5p and ZEB1 mRNA were downregulated in breast cancer tissues compared to adjacent normal tissues. There was no relationship between miRNA-139-5p and response to neoadjuvant chemotherapy containing docetaxel. Analysis of TCGA data shows that miRNA-139-5p is downregulated in breast cancer tissues especially in basal-like breast cancer tissues, and is a prognostic factor for poor overall survival in basal-like breast cancer.Conclusions:MiRNA-139-5p enhances chemosensitivity of breast cancer cells to docetaxel and inhibits migration by targeting ZEB1. However, it is a prognostic factor for poor overall survival in basal-like breast cancer.