MicroRNA-130b Targets PTEN To Mediate Drug Resistance And Proliferation Of Breast Cancer Cells Via The PI3K/Akt Signaling Pathway

Objective: To clarify the mechanism of miR-130 b targeting PTEN on chemoresistance and proliferation via PI3K/Akt signaling pathway of breast cancer,we investigated the differential expression of miR-130 b and PTEN in breast cancer tissues and cell lines,which may provide a new treatment strategy for breast cancer.Methods:(1)The differential expression of miR-130 b and PTEN in breast cancer tumor tissues(tumor tissues and adjacent tissues)and breast cancer cells(parental line MCF-7 and ADR resistant breast cancer cell line MCF-7/ADR)were detected by real-time PCR.(2)Over-expression of miR-130 b in MCF-7 cells and suppression of miR-130 b in MCF-7/ADR cells and the expression of PTEN in those cells was detected by real-time PCR、Western Blot and Immunofluorescence staining assays.(3)The relationship of miR-130 b and PTEN were verified by using bioinformatics technology and dual luciferase experiments.(4)We used CCK8、colony formation、flow cytometry、immunofluorescence staining 、 tumorigenicity and immunohistochemical staining analysis to verify the changes of drug sensitivity and proliferation of breast cancer cells in vitro and in vivo.(5)To determine the altered expression of PTEN-PI3K/Akt pathway and the changes of drug sensitivity and proliferation,miR-130 b and PTEN expression were upregulated simultaneously in MCF-7 cells,and miR-130 b and PTEN expression were downregulated simultaneously in MCF-7/ADR cells.Results:(1)MiR-130 b was found to be up-regulated in tumor tissues versus adjacent tissues of breast cancer,as well as in adriamycin(ADR)resistant breast cancer cell line(MCF-7/ADR)versus its parental line(MCF-7)and PTEN was inversely correlated with miR-130 b expression in breast cancer.(2)Over-expression of miR-130 b reduced the expression of PTEN in MCF-7 cells;suppression of miR-130 b increased the expression of PTEN in MCF-7/ADR cells.(3)PTEN was a direct target of miR-130 b.(4)Over-expression of miR-130 b promoted drug resistance and proliferation of MCF-7 cells,while suppression of miR-130 b enhanced drug cytotoxicity and reduced proliferation of MCF-7/ADR cells in vitro and in vivo.(5)Over-expression of miR-130 b increased the expression of PI3K/Akt pathway in MCF-7 cells.MiR-130 b over-expression mediated increased chemoresistance and proliferation of MCF-7 cells was partially blocked following up-regulation of PTEN.Downregulation of miR-130 b reduced the expression of PI3K/Akt pathway in MCF-7/ADR cells.MiR-130 b downregulation mediated decreased chemoresistance and proliferation of MCF-7ADR cells was partially blocked following knockdown of PTEN.Conclusion:(1)The expression of miR-130 b and PTEN in human breast cancer tissues and drug-resistant cell lines were significantly different and negatively correlated.(2)The different expression of miR-130 b and PTEN in human breast cancer tissues and drug-resistant cell lines is associated with multidrug resistance and proliferation of breast cancer.(3)MiR-130 b may target PTEN to induce MDR,proliferation via PI3K/Akt signaling pathway.