Forskolin inhibits basal and IR-induced p53 levels in BCP-ALL blasts but not in normal BCPs. (A) BCP-ALL blasts from 10 patients were cultured in the presence or absence of 60 μM forskolin prior to IR as described in Figure 1A. At 4 h after irradiation, cells were harvested and subjected to immunoblot analysis with antibodies directed against p53 and GAPDH. The immunoblot shows the results from 1 representative patient (ALL5). Densitometric analysis of the immunoblots was performed as described in Materials and Methods. The calculated fold change in p53 intensity is presented as a scatter plot (n = 10, lines indicate median values; *P < .05 by Wilcoxon’s signed rank test). (B) The relative reduction in p53 intensity induced by forskolin on nonirradiated and irradiated cells was calculated for each sample represented in Figure 2A and presented as a scatter plot (n = 10, lines indicate median values). (C) Freshly isolated normal BCPs from 7 donors were treated with forskolin and IR as described in Figure 1A. At 4 h after irradiation, cells were harvested and flash frozen in N2 before storage at −80°C. For sufficient cell material, samples from 2 or 3 different donors were pooled for immunoblot analysis with antibodies against p53 and GAPDH. The figure shows 1 representative experiment of 3.
