Aminoguanidine reversal of the inhibitory effects of ornithine analogs on the in vitro clonogenic survival of the R3327AT prostate-derived tumor.

In in vitro studies with the Copenhagen rat prostate-derived tumor cell lines, the activity of ornithine decarboxylase (ODC) of these lines were as sensitive to inhibition by alpha-difluoromethylornithine (alpha-DFMO) as normal prostatic tissue. The in vitro growth of the tumor in calf serum was inhibited by ODC inhibitors alpha-methylornithine and alpha-difluoromethylornithine. This inhibition was partially reversed by the diamine oxidase inhibitor aminoguanidine. Further, alpha-DFMO was not inhibitory to the growth of these cells in sera which lacked diamine oxidase activity, but was inhibitory when diamine oxidase was added.