Urokinase-type plasminogen activator in colorectal carcinomas and adenomatous polyps: quantitative expression of active and proenzyme.

Total urokinase-type plasminogen activator (u-PA) content (proenzyme plus active enzyme) was significantly higher in 20 colorectal carcinomas and in 27 adenomatous polyps than in metaplastic polyps and autologous normal mucosa. u-PA content was also markedly increased in adenomatous polyps and autologous colonic mucosa removed from familial polyposis coli patients. Using a new monoclonal antibody technique to distinguish the proenzyme of u-PA from the active enzyme, we found that 70% of the u-PA in polyp and cancer tissue was present in the proenzyme form compared to 47% in normal colonic mucosa. For colon cancers, there was a significant correlation between their stage of invasiveness and the levels of proenzyme. No correlation was observed between the u-PA content of adenomatous polyps and their size or degree of dysplasia. Study of the u-PA content of the colonic mucosa may offer a useful biochemical correlate of epithelial cell transformation in the colon.