MicroRNA-27a-3p Reverses Adriamycin Resistance by Targeting BTG2 and Activating PI3K/Akt Pathway in Breast Cancer Cells.

Aim: This study aimed to explore the regulative mechanisms of miR-27a-3p in chemo-resistance of breast cancer cells.

Materials And Methods: qRT-PCR was employed to determine miR-27a-3p expression in two breast cancer cell lines, MCF-7 and MCF-7/adriamycin-resistant cell line (MCF-7/ADR). The two cell lines were treated with miR-27a-3p mimics or inhibitors or corresponding negative control (NC), respectively. The changes were investigated by qRT-PCR, CCK-8 assay, Western blot (WB), colony formation assay, and flow cytometry assay. Moreover, luciferase reporter assay was analyzed to verify the downstream target gene of miR-27a-3p. Further investigation in the correlation between miR-27a-3p and BTG2 was launched by WB, flow cytometry assay, and CCK-8 assay. The expression of Akt and p-Akt was detected by WB.

Key Findings: Significantly higher miR-27a-3p expression was confirmed in MCF-7/ADR as compared with sensitive cell line MCF-7 (<0.05). The down-regulation of miR-27a-3p in MCF-7/ADR enhanced the sensitivity of cancer cells to adriamycin treatment, decreased multidrug resistance gene 1/P-glycoprotein (MDR1/P-gp) expression, enhanced the apoptosis-related proteins expression, increased adriamycin-induced apoptosis, and inhibited cell proliferation as compared to NC groups (<0.05). The up-regulation of miR-27a-3p in MCF-7 showed the opposite results. BTG2 is identified as a direct target of miR-27a-3p and its down-regulation reversed ADR-resistance. BTG2 treatment exhibited inhibitory effect on PI3K/Akt pathway in MCF-7/ADR cells.

Significance: miR-27a-3p might be associated with resistance of breast cancer cells to adriamycin treatments, modulating cell proliferation and apoptosis by targeting BTG2 and promoting the PI3K/Akt pathway in breast cancer cells. miR-27a-3p/BTG2 axis might be a potential therapeutic target for clinical BC resistance.