AMINOGUANIDINE INHIBITS CELL-PROLIFERATION BY PROLONGATION OF THE MITOTIC PHASE

Aminoguanidine has been reported to increase mitotic cells in the live r and to retard the development in chick embryos. In this study, in vi tro effects of aminoguanidine on mammalian cells, BRL-3A (from normal rat liver) and HeLa-S3 (from human cervical cancer), were examined. Wh en cells were incubated with varying concentrations of aminoguanidine for 48 h, the cell growth was inhibited at high concentrations of amin oguanidine, without cell death; the 50% growth-inhibitory concentratio ns (IC50) against BRL-3A and HeLa-S3 cells were 4.6 and 2.2 mg/ml, res pectively. After culture with aminoguanidine for 24 h, the proportion in the G2/M-phase in both cell lines was increased, but the proportion in the G1-phase was decreased, and the rate in the S-phase was slight ly increased at low concentrations of this agent and decreased at high concentrations. The effects of aminoguanidine on the increase in the G2/M-phase in HeLa cells were dose-dependent. In synchronized HeLa cel ls, aminoguanidine clearly prolonged the M-phase. From these results, it is confirmed that aminoguanidine inhibits cell proliferation by pro longing the M-phase in the cell cycle in mammalian cells as well as ch ick embryo liver cells.