Expression of angiostatic factors in colorectal cancer.

Angiogenesis plays an important role in growth and proliferation of cancer. Various angiogenic and angiostatic factors regulate angiogenesis. We examined expression of genes encoding various angiostatic factors: thrombospondin 1 (TSP1), thrombospondin 2 (TSP2), brain-specific angiogenesis inhibitor 1 (BAI1) and angiopoietin 2 (AGP2) in 62 colorectal cancers and 40 samples of extraneoplastic colon mucosa. The expression of the angiostatic factors TSP2 and AGP2 were significantly increased in the cancerous mucosa as compared to these in extraneoplastic mucosa (o2 test; p<0. 0001, and Fisher's exact test; p<0.0001), while the increase in TSP1 expression was not significant. BAI1 expression was slightly decreased in the cancer tissue. These results suggested that specific types of angiostatic factors might have protective roles against cancer cell proliferation via dormancy due to hyponutrition caused by decreased vascularity.