Inhibition of ornithine decarboxylase activity and cell growth by diamines: a comparison between the effects of two homologs, 1,3-diaminopropane and 1,4-diaminobutane (putrescine).

The ornithine decarboxylase (ODC) activity of Ehrlich ascites tumor cells was almost completely inhibited by treatment with either putrescine (10 mM) or 1,3-diaminopropane (5 mM). 1,3-Diaminopropane treatment eradicated the cellular content of putrescine and reduced that of spermidine and spermine. Putrescine treatment caused a dramatic increase in cellular putrescine content and a temporary decrease in spermidine and spermine content. Despite the fact that 1,3-diaminopropane and putrescine inhibited the ODC activity more effectively than did alpha-difluoromethylornithine (DFMO), an enzyme-activated irreversible inhibitor of ODC, they were considerably less antiproliferative in action. However, as compared to DFMO the diamines were less effective in reducing the total polyamine (putrescine + spermidine + spermine) content of the cells.