MicroRNA-301a Mediates Doxorubicin Resistance by Up-Regulating the NF-κB in Breast Cancer

Abstract

Background: MicroRNA-301a (miR-301a) is related to tumor development, metastases, and poor prognosis in patients. Primary or acquired doxorubicin (DOX) resistance often leads to failure in breast cancer treatment. The aim of this study was to analyze the relationship between miR-301a and DOX resistance in breast cancer. Methods: Human breast cancer MCF-7 (human breast cancer cell line) cells stably overexpressing miR-301a were constructed by a lentivirus-mediated overexpression system. The expression of miR-301a in MCF-7 cells was detected by quantitative real-time PCR (qRT-PCR). The activity of MCF-7 cells was determined by CCK-8 (Cell Counting Kit-8) assay, and the apoptosis was analyzed by Western blotting and flow cytometry. Western blotting was used to examine the expression of phosphorylated p65 and IκB-α (inhibitor of NF-κB-α) protein. qRT-PCR and dual luciferase reporter assays were performed to verify whether miR-301a regulates NF-κB (nuclear factor kappa-B) and involves in DOX resistance in breast cancer. Results: DOX led to upregulation of miR-301a expression in MCF-7 cells, while miR-301a expression was significantly increased in miR-301a-overexpressed MCF-7 cells treated with DOX and dimethyl sulfoxide (DMSO). Overexpression of miR-301a impeded the inhibition of DOX on MCF-7 cell viability and promotion of apoptosis. MCF-7 cells treated with NF-κB inhibitor showed increased DOX resistance and decreased apoptosis levels upon miR-301a overexpression. Moreover, miR-301a overexpression increased phosphorylated IκB-α and p65 proteins. The mRNA (messenger RNA) level of IκB-α decreased after adding DOX. Conclusions: miR-301a/NF-κB pathway may be a novel target for enhancing DOX sensitivity in breast cancer patients.