Relation between p53 dysfunction and radiation-induced killing.

CLL cells from all 43 patients were tested for their sensitivity to killing by (A) γ-radiation (5 Gy) or (B) staurosporine (0.1 μM). Cell viability was measured by PI exclusion and flow cytometry (C). Mean survival values (± SE) are plotted against time. The difference in radiation-induced killing between cells with functionally intact p53 and those with type B p53 dysfunction and ATMmutations was highly significant (P < .001 by Student t test). In contrast, there were no differences among the 3 groups in their sensitivity to staurosporine-induced and spontaneous cell death. ▴ indicates TP53 mutated (n = 6); ▪, ATM mutated (n = 7); and ●, no p53 dysfunction (n = 30).