Functional inactivation of p53 by HPV-E6 transformation is associated witha reduced expression of radiation-induced potentially lethal damage

Purpose: To examine the effect of functional loss of p53 on radiation sensi tivity and potentially lethal damage repair (PLDR). Materials and methods: Radiation sensitivity and PLDR were examined in an i sogenic pair of human tumour cell lines created by HPV-EG transformation. Results: Inactivation of p53 by E6 transformation resulted in a cell line t hat was more resistant to killing by radiation but showed little enhancemen t in survival (PLDR) when plateau-phase cells were held non-cycling after r adiation exposure. Holding p53-normal cells in plateau-phase after radiatio n exposure not only led to enhanced survival, but also to a reduction in th e proportion of cells that blocked in G(1) subsequent to release. Conclusions: These results suggest that p53 expression influences that comp onent of radiation sensitivity associated with PLDR.