High ornithine decarboxylase activity and polyamine levels in human colorectal neoplasia.

Polyamines are required for cell proliferation, and ornithine decarboxylase (ODC) is the first and probably rate-limiting enzyme in their synthesis. Tissue containing colonic or rectal adenocarcinomas (N = 34) or polyps (N = 6) and noninvolved paired colonic mucosa were obtained from fresh surgical specimens. ODC activity was elevated (mean: 320%) in both the cancer and polyps. In noninvolved colonic mucosa of tumor-bearing specimens, ODC activity was 165% that of colonic mucosa of non-neoplastic disease. Concentrations of polyamines in neoplasms were 121-214% increased, as compared with normal mucosa; those of spermidine and spermine varied inversely with the histological grade of the tumor. High levels of ODC activity and of polyamines were features of neoplasia, but not of malignancy alone. These characteristics of colonic neoplasia suggest its susceptibility to control by inhibition of ODC.