EFFECTS OF ACLACINOMYCIN ON CELL-SURVIVAL AND CELL-CYCLE PROGRESSION OF CULTURED MAMMALIAN-CELLS

  • 1 January 1981
    • journal article
    • research article
    • Vol. 41  (7) , 2728-2737
Abstract
The effects of aclacinomycin (ACM; NSC 208734) on cell viability, growth and colony formation were investigated in suspension (Friend [murine] leukemia [virus-transformed cells] and [mouse leukemia] L1210) and adherent (Chinese hamster ovary) cell systems. Cell cycle progression and the effect of the drug on various transition points in the cell cycle (i.e., G1 to S phase, through a window in early S phase and G2 phase to mitosis) were monitored by flow cytometry. Formation of Chinese hamster ovary cell colonies was inhibited by 50% following 24 h of exposure to 0.05 .mu.g ACM/ml; 1 h of exposure to 1.0 .mu.g ACM/ml reduced colony formation by only 30%. Stationary cultures required a drug concentration > 5 times higher to reduce colony formation by an equivalent amount when present for 24 h. Short-term (1 h) exposure to drug concentrations up to 1.0 .mu.g/ml had no effect on colony formation of stationary-phase Chinese hamster ovary cells. Cell growth was inhibited by 50% in suspension cultures of Friend leukemia and L1210 cells when exposed for 24 h to 0.024 and 0.053 .mu.g ACM/ml, respectively. Continuous drug exposure of Friend leukemia and L1210 cells to ACM concentrations of 0.05-0.1 .mu.g/ml led to a slow down in cell progression manifested as an accumulation of cells in G2 + M phase by 24 h and then in G1 phase by 48 h culture. Brief (1 h) exposure of L1210 cells to 0.5 .mu.g/ml resulted in an irreversible accumulation of cells in G2 + M phase. A more detailed examination of drug effects on the cell cycle determined that 0.1 .mu.g ACM/ml resulted in a slow down in L1210 cells leaving G1 phase and entering mitosis and an accumulation of cells in G2 phase although early S-phase cells appeared unaffected. At a 5-fold higher drug concentration, exit of cells from G1 was almost completely halted, passage of cells through early S was slowed and the entrance of cells into mitosis plateaued 3.5 h after addition of the drug; G2-phase cells were only mildly affected. The RNA content of all cells examined was reduced by 35-50% depending upon dose and time of exposure. These findings are discussed in terms of the known biochemical effects of ACM on RNA and protein synthesis.