The Effect of Adriamycin on the Cell Cycle Traverse of a Human Lymphoid Cell Line

The kinetic response of a human lymphoma cell line to adriamycin was analyzed by means of pulse cytophotometry. Depending on concentration and exposure time, cell cycle progression was delayed in G, S, and G₂phases. There was a differential sensitivity for the interaction of adriamycin with the transit through these phases. G₂arrest could be induced by low concentrations of adriamycin, whereas the block in G, was exerted only after long-term treatment with high concentrations and was completely reversible after drug removal. Delay in S-phase transit was transient in spite of continuous exposure to high concentrations of adriamycin. Thus, concentration and duration of treatment determined the magnitude of G₂arrest as well as onset and rate of G₂accumulation due to progression delay in G, and S phases. Cell age had only little influence on the degree of subsequent G₂arrest. Irreversibility of the G₂block strongly suggests eventual cell death in G₂phase, which may be utilized as a predictive test for response to adriamvcin in vivo.