A clonal human chondrosarcoma cell line produces an anti-angiogenic antitumor factor

Previously we reported that rabbit costal chondrocytes in primary culture produced an anti-angiogenic anti-tumor factor. We also established a clonal human chondrosarcoma cell line, HCS-2/8, which had typical cartilage phenotypes. In the present study, we investigated whether HCS-2/8 cells produce an anti-angiogenic anti-tumor factor. Serum-free medium conditioned by exposure to HCS-2/8 cells in culture inhibited the proliferation of bovine pulmonary artery endothelial cells in culture. The inhibition was not due to general cytotoxicity because the endothelial cells started to proliferate after the conditioned medium was removed from the cultures. The factor in conditioned medium also inhibited DNA synthesis in bovine pulmonary artery endothelial cells, but not in B16 melanoma cells, normal rat kidney cells or chick embryo fibroblasts. Production of the factor by HCS-2/8 cells did not change during serial passages. It also inhibited angiogenesis in the chorioallantoic membrane of chick embryos induced by B16 melanoma and growth of the tumor transplanted onto the membrane. Treatment with protease destroyed the inhibitory activities of conditioned medium on angiogenesis and tumor growth. These findings suggest that HCS-2/8 cells produce a peptide factor with anti-angiogenic, antitumor activity and that the cell line should be a useful source of the factor.