Abstract: Objective To explore the effects of breast cancer cell exosomes miR-27a on the polarization of macrophages and on tumor growth and metastasis. Methods qRT-PCR was used to detect the expression of miR-27a in M1 and M2 macrophages,and to detect the effect of miR-27a on the polarization of macrophages.Differential centrifugation was used to extract breast epithelial cells MCF10A and breast cancer cells MDA-MB-231 exosomes,qRT-PCR to detect the expression of miR-27a in exosomes,to detect the effect of exosomes miR-27a on the polarization of macrophages,and culture the macrophages after exosomes induction After the base supernatant(CM) was incubated with MDA-MB-231 cells,the proliferation,migration and invasion ability of MDA-MB-231 cells were detected.Results miR-27a was highly expressed in M2 type macrophages(P＜0.05),and miR-27a mimic significantly promoted the expression of CD206 and MRC-2(P＜0.05),and miR-27a inhibitor inhibited the expression of CD206 and MRC-2(P＜0.05),miR-27a was highly expressed in MDA-MB-231 exosomes(P＜0.05),MDA-MB-231 exosomes can significantly promoted the polarization of M2 macrophages(P＜0.05).The polarized macrophage culture supernatant could significantly induce the proliferation,migration and invasion of MDA-MB-231 cells(P＜0.05),and MDA-MB-231 exosomes with low expression of miR-27a could significantly inhibit M2 Type macrophages were polarized(P＜0.05),and the M2 type cell culture supernatant could significantly inhibit the proliferation,migration and invasion of MDA-MB-231 cells(-P-＜0.05).Conclusion The breast cancer cell exosomes miR-27a can promote the polarization of M2 macrophages and promote the growth and metastasis of breast cancer cells.

Key words: exosomal miR27a, 〓M2 type macrophage polarization, 〓breast cancer, 〓growth and metastasis