OBJECTIVETo study the effect of alternatively activated macrophages /mononuclear phagocytes(MNP) on breast cancer cells and explore the mechanisms for the action of tumor-associated macrophages in breast cancer.

METHODSHuman peripheral blood monocytes were isolated and cultured in vitro and divided into 3 groups, namely classically activated monocytes (CAM) which were induced by lipopolysaccharide, alternatively activated monocytes (AAM) induce by IL-4, and control cells treated with the culture medium only. After cell culture for 48-72 h, the mRNA of tumor necrosis factor-alpha (TNF-alpha), alternative monocytes activation- associated CC-chemokine 1 (AMAC-1), and beta-actin of the 3 groups were extracted for RT-PCR, or the cells were cocultured with breast cancer cell line SKBR3, or seeded in chicken chorioallantoic membrane along with SKBR3.

RESULTSTNF-alpha mRNA was significantly increased in CAM, and AMAC-1 was highly expressed in AAM. The coculture experiments showed that CAM exhibited obvious inhibitory effect on SKBR3 cells after a 3-day culture whereas AAM significantly promoted the growth of SKBR3 cells after a 5-day culture. In chicken on chorioallantoic membrane experiment, the macrophages promoted tumor angiogenesis and AAM showed the most obvious effect.

CONCLUSIONIL-4 induces high expression of AMAC-1, a molecular marker of AAM, in the macrophages, and AAM can promote the growth of SKBR3 cells and tumor angiogenesis.