Interaction of monocytes/macrophages with ovarian cancer cells promotes angiogenesis in vitro

It has been established that macrophages and endothelial cells infiltrate peritoneum in the vicinity of tumor implants of epithelial ovarian cancer (EOC). This study investigates whether the interaction of ovarian cancer cells and tumor-associated macrophages could promote the involvement of endothelial cells in angiogenesis. Macrophage phenotypes were detected by fluorescence-activated cell sorting, and cytokine/chemokine secretion was measured by enzyme linked immunosorbent assay. The effect of co-culture of ovarian cancer cells and tumor-associated macrophage (TAM) cells on endothelial cell migration and tube formation was investigated. Signaling pathway mediators were also evaluated for their potential roles in endothelial cell activation by ovarian cancer cells co-cultured with TAM cells. Our results showed that higher expression of interleukin-8 (IL-8) expression associated with 54.26 +/- 34.46% of TAM infiltration of peritoneum was significantly higher than 16.58 +/- 17.74% of CD3+ T-cell by immunofluorescence co-staining and confocal microscopy. THP-1 cells exhibited M2-polarized phenotype markers with high proportion of CD68+, CD206+ and CD204+ markers after phorbol 12-myristate 13-acetate (PMA) treatment, After co-culturing with TAM cells in a transwell chamber system, EOC cells (SKOV3) increased their IL-8 expression at the level of mRNA and protein. After exposure to the conditioned medium obtained by co-culturing TAM and SKOV3 cells, the migration and tube formation of endothelial cells were enhanced significantly. Furthermore, the upregulation of IL-8 expression in ovarian cancer cells induced by macrophages could be inhibited by pyrollidine dithiocarbamate, an inhibitor of nuclear factor (NF)- B signal pathway. We suggest that the interaction of ovarian cancer cells and tumor-associated macrophages enhances the ability of endothelial cells to promote the progression of ovarian cancer. (Cancer Sci 2013; 104: 516-523)