elevation of camp levels inhibits doxorubicin-induced apoptosis in pre- b all nalm- 6 cells through induction of bad phosphorylation and inhibition of p53 accumulation

recognition of the molecular mechanisms of camp action against dna damage-induced apoptosis can be useful to improve the efficacy of dna damaging therapeutic agents. considering the critical role of bcl-2-associated death promoter (bad) and p53 proteins in dna damage -induced apoptosis, the aim of this study was to assess the effect of camp-elevating agents on these proteins in doxorubicin-treated pre-b acute lymphoblastic leukemia (pre-b all) nalm-6 cells.the pre-b all cell line nalm-6 was cultured and treated with doxorubicin in combination with or without camp-elevating agents forskolin and 3-isobutyl-1-methylxanthine (ibmx). cell viability was measured by trypan blue staining and mtt assay. for evaluation of apoptosis, annexin-v staining by flow cytometry and caspase-3 activity assay were used. protein expression of p53, bad and phoshorylated bad was detected by western blotting analysis.camp-increasing agents diminished the doxorubicin-mediated cytotoxicity in nalm-6 cells as indicated by the viability assays. annexin-v apoptosis assay showed that the camp-elevating agents decreased doxorubicin-induced apoptosis. moreover, doxorubicin-induced caspase-3 activity was attenuated in the presence of camp-increasing agents. western blot results revealed the reduced expression of p53 protein in cells treated with combination of camp-elevating agents and doxorubicin in contrast to cells treated with doxorubicin alone. expression of total bad protein was not affected by doxorubicin and camp-elevating agents. however, phosphorylation of bad protein was induced in the presence of camp-elevating agents. our study suggests that elevated camp levels inhibit doxorubicin-induced apoptosis in pre-b all cells through induction of bad phosphorylation and abrogation of p53 accumulation.