Aminoguanidine inhibits cell proliferation by prolongation of the mitotic phase

Aminoguanidine has been reported to increase mitotic cells in the liver and to retard the development in chick embryos. In this study, in vitro effects of aminoguanidine on mammalian cells, BRL-3A (from normal rat liver) and HeLa-S3 (from human cervical cancer), were examined. When cells were incubated with varying concentrations of aminoguanidine for 48 h, the cell growth was inhibited at high concentrations of aminoguanidine, without cell death; the 50% growth-inhibitory concentrations (IC50) against BRL-3A and HeLa-S3 cells were 4.6 and 2.2 mg/ml, respectively. 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 slightly 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 cells, aminoguanidine clearly prolonged the M-phase. From these results, it is confirmed that aminoguanidine inhibits cell proliferation by prolonging the M-phase in the cell cycle in mammalian cells as well as chick embryo liver cells.