miR-382-5p affects polarization of tumor-associated macrophages in breast cancer through Akt/mTOR signaling pathway

Abstract

Objective To investigate the effects of microRNA-382-5p (miR-382-5p) expression in breast cancer tumor-associated macrophages (TAMs) on the polarization phenotype of macrophages as well as the biological characteristics of breast cancer, and to explore its possible mechanism. Methods Breast cancer TAMs and their paring macrophages from adjacent tissues of 25 breast cancer patients treated in our hospital between 2018 and 2020 were collected, and the expression of miR-382-5p was detected by qRT-PCR. Mouse peritoneal macrophages (PMs) were transfected with miR-382-5p over-expressed lentivirus. The changes of M1/M2 polarization indicators (iNOS, TNF-α, Arg-1, IL-10, etc.) and the expression of miR-382-5p and Akt/mTOR signaling pathway were determined by qRT-PCR and Western blotting, and the expression of CD86 and CD206 were tested using flow cytometry. After the 4T1 mouse breast cancer cells were co-cultured with TAMs and TAMs overexpressing miR-382-5p, respectively, or treated with the corresponding supernatants, the proliferative capacity of 4T1 cells was subsequently tested by CCK-8 assay, the invasion ability and the migration ability of 4T1 cells were observed using Transwell assay and cell scratch assay, respectively. Results The level of miR-382-5p in breast cancer TAMs was significantly lower than that in macrophages of pairing adjacent tissues (P < 0.05). Compared with the control group, the levels of M1-phenotype polarization markers (iNOS, TNF-α, CD86, etc.) were increased, while those of M2 indicators (Arg-1, IL-10, CD206) were decreased in the miR-382-5p overexpressed group (P < 0.05), and the phosphorylation levels of the proteins related to Akt/mTOR signaling pathway were reduced (P < 0.05). In addition, the abilities of proliferation, invasion and migration of 4T1 cells were all inhibited in the miR-382-5p overexpressed group as compared with the TAMs group (P < 0.05). Conclusion miR-382-5p may possibly play a vital role in the invasion and migration processes of breast cancer cells by affecting the polarization phenotypes of TAMs, and the mechanism may be associated with miR-382-5p mediated Akt/mTOR signaling pathway in the regulation of macrophage polarization.

Keywords

• breast cancer
• tumor-associated macrophages
• microrna
• akt/mtor signaling pathway