en Cancer Cancer Original Article Original Article 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. Doxorubicin, Apoptosis, cAMP, p53, BAD 94 102 http://ijmcmed.org/browse.php?a_code=A-10-353-1&slc_lang=en&sid=1 Ahmad Fatemi ahmad.fatemi2@gmail.com 10031947532846004907 10031947532846004907 No Department of Hematology, School of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran. Ahmad Kazemi a.kazemi32@gmail.com 10031947532846004908 10031947532846004908 No Department of Hematology, School of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran. Meysam Kashiri majidsafa@gmail.com 10031947532846004909 10031947532846004909 No Department of Hematology, School of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran. Majid Safa safa.m@iums.ac.ir 10031947532846004910 10031947532846004910 Yes Department of Hematology, School of Allied Medicine, Iran University of Medical Sciences, Tehran, Iran.