Abstract: Objective To investigate the influence of miR-146a on the function of tumor-associated macrophage (TAM), and the mechanism of its expression regulation. Methods We compared TAM in 4T1 xenografted tumor grown in BALB/c mouse to peritoneal macrophage (PEC), and TAM in human breast cancer to PBMC respectively to detect the expression level of miR-146a using q-PCR method. Mixed implantation subcutaneously of miR-146a antagomir-transfected macrophages with 4T1 cells was used to determine the function of miR-146a in TAM. Results miR-146a was significantly down-regulated in breast cancer-associated macrophage in both 4T1 tumor grown in mice (P<0.05) and breast cancer patients (P<0.01). It was observed that macrophage with decreased miR-146a expression inhibited the 4T1 tumor cell growth in vivo. Conclusion miR-146a can regulate tumor associated macrophage function, so as to promote tumor growth.

Key words: microRNA, tumor associated macrophage, miR-146a