Effects of benzaldehyde on survival and cell-cycle kinetics of human cells cultivated in vitro.

Synchronized cells of the human line NHIK 3025 were used to study inactivating and cell-cycle inhibitory effects induced by benzaldehyde. Inactivation was measured as loss of colony-forming ability after treatment of exponentially growing or synchronized cells. Cell-cycle inhibition was measured by flow cytometric recordings of DNA-histograms and microscopic recordings of cell division in synchronized cells. Treatment with benzaldehyde for 4 or 24 hr showed that a marked decrease in survival took place for concentrations above 6.4 mM. Cell-cycle inhibition was observed at concentrations as low as 0.8 mM. Synchronized cells were treated with 3.2 and 6.4 mM benzaldehyde for 8 hr starting at various stages of the cell-cycle. Both the colony-forming ability and the rate of cell-cycle traverse was measured. No difference in sensitivity was found whether the treatment was given in G1, S or in G2. Thus the results show that there is no specific part of interphase where the cells are particularly sensitive with respect to either the inactivating or the cell-cycle inhibitory effects of benzaldehyde in concentrations up to 6.4 mM. When benzaldehyde was present during mitosis both the inactivating and the cell-cycle inhibitory effects were markedly enhanced as compared to the corresponding effects during interphase. It is concluded that benzaldehyde must affect some process within the cell which represents a general requirement for cell-cycle progression. In addition, there are effects on processes that take place only during the last few minutes before and/or during mitosis.