Tumor and tumor-microenvironment are most important aspects in recent years. Tumor associated macrophages (TAM) play key roles in tumor-microenvironment. Macrophages are originated from blood monocytes. In this study, we examined whether DU145 androgen-independent prostate cancer cells and THP-1 human monocytes interact each other in vivo and in vitro. In vivo xenograft model, DU145 cells and/or THP-1 cells were inoculated subcutaneously in Balb/c nude mice. Tumor growth was accelerated in a group of co-inoculation of DU145 cells with THP-1 cells compared to only DU145 or THP-1 cell-injected group. Immunohistochemistry assay in tumors revealed that Ki67, CD31, and vascular endothelial growth factor (VEGF) expressions were increased by the co-inoculation group. Secretion of IL-6, IL-8 or VEGF were induced when DU145 cells incubated with THP-1 cells. In the present study, we demonstrated that increase of IL-6, IL-8 and VEGF secretion in co-culture of DU145 and THP-1 cells may one of the key inducers of promotion in tumor growth of co-inoculation with DU145 human prostate cancer cells and THP-1 human monocytes. (Cancer Prev Res 16, 194-199, 2011)

Keywords: Androgen-independent DU145 human prostate cancer cells, THP-1 human monocytes, Tumor growth, IL-6, IL-8