In in vitro angiogenesis assays, aggregates of human papilloma virus (HPV)-18-immortalized primary human prostate cancer cells (HPCA-5aHPV-18 or HPCA-10aHPV-18 cells) induced human bone marrow endothelial cells (HBMCE-1 cells) to form microvessels in three-dimensional collagen I gels after 1-2 days incubation at 37 degrees C. The microvessels aligned perpendicular to the tumor aggregates and abutted on the edges of the aggregates. The number and length of the microvessels increased significantly from day 1 to 2 (i.e., by approximately 30%). ELISAs showed that the HPCA-5aHPV-18 cells normally secreted low levels of tissue inhibitor of metalloproteinase (TIMP)-2, matrix metalloproteinase (MMP)-2, and MMP-9 but relatively high levels of TIMP-1. In contrast, HPCA-10aHPV-18 cells secreted high levels of MMP-2 and MMP-9 (>40 pg/microg protein) but low levels of TIMP-1 and TIMP-2 (<5 pg/microg protein). Interleukin 10 (IL-10) (15 ng/ml) induced TIMP-1 production (>15 pg/microg protein) but reduced MMP-2 and MMP-9 secretion (<5 pg/microg protein) by the HPCA-5aHPV-18 and HPCA-10aHPV-18 cells. IL-10 (15 ng/ml) and MMP-9/MMP-2 antibodies all blocked induction of microvessel formation in the coculture experiments. In contrast, IL-10 receptor antibodies and TIMP-1 antibodies countered IL-10's effects and promoted angiogenesis. The data demonstrated that IL-10 stimulation of TIMP-1 and inhibition of MMP-2 and MMP-9 secretion by prostate tumor cells can control induction of angiogenesis in vitro.