Effect of Aphidicolin on DNA Synthesis, PLD-recovery and DNA Repair of Human Diploid Fibroblasts

Abstract

The effect of aphidicolin, a specific inhibitor of DNA polymerases α and δ, was studied on DNA synthesis, PLD-recovery and DNA double-strand break rejoining in X-irradiated human fibroblasts. In unirradiated, exponentially growing cells, aphidicolin (0·5–5 µg ml) inhibited DNA synthesis almost completely. This effect depended not only on aphidicolin concentration but also on the duration of pre-incubation. The action of aphidicolin was found to be reversible. When aphidicolin had been removed, colony forming ability was not affected in aphidicolin pretreated cells. Aphidicolin pretreated and irradiated cells showed a reduction in PLD-recovery, dependent on aphidicolin concentration and duration of pretreatment. The initial number of DNA double-strand breaks (calibrated by ¹²⁵I decay) was not affected by aphidicolin. However, after incubation for 90 min in the presence of aphidicolin there was a large reduction in double-strand break rejoining. With long incubation periods in aphidicolin rejoining was almost completely inhibited.