High local polyamine concentrations may suppress cell growth of primary prostatic carcinomas. When cell growth assays were conducted in defined serum-free medium, spermine inhibited the growth of poorly metastatic rat prostate carcinoma cells, causing cell cycle arrest in the G1 phase. In contrast, highly metastatic prostate carcinoma cells were resistant to the growth inhibitory activity of spermine. Ornithine decarboxylase antizyme levels, measured by Western blotting, were elevated 1-2 h after spermine treatment of spermine-sensitive cells but not spermine-resistant cells. Spermine uptake was similar in both the sensitive and resistant cell lines. These results suggest that failure to induce antizyme correlates with spermine resistance in prostate carcinoma.