Recovery from ultraviolet-induced growth arrest of primary rat hepatocytes by p53 antisense oligonucleotide treatment

Recent evidence suggests that wild-type p53 prevents cell-cycle progression after DNA damage, which may provide a sufficient period for the cells to repair the genetic lesions that may otherwise lead to cell death or cellular transformation. We tested whether this hypothesis is generally applicable to parenchymal cells of internal organs. When primary neonatal rat hepatocytes were exposed to a nonlethal dose of ultraviolet light, actinomycin D, or mitomycin C, most cells expressed abundant p53 with an abnormally extended half life in their nuclei, and their growth was arrested despite treatment with growth factors (epidermal growth factor and insulin). When DNA-damaged cells were treated with p53-antisense oligonucleotides, p53 expression was significantly suppressed, and an appreciable fraction of the cells entered S phase. However, when damaged cells were administered p53-sense or retinoblastoma susceptibility gene-antisense oligonucleotides, there was no recovery from growth arrest. The data strongly suggest that p53 is a component of at least one signal transduction pathway leading to growth arrest in DNA-damaged cells.