Inhibition of DNA-dependent protein kinase catalytic subunit by small molecule inhibitor NU7026 sensitizes human leukemic K562 cells to benzene metabolite-induced apoptosis.
You-H; Kong-M-M; Wang-L-P; Xiao-X; Liao-H-L; Bi-Z-Y; Yan-H; Wang-H; Wang-C-H; Ma-Q; Liu-Y-Q; Bi-Y-Y
J Huazhong Univ Sci Technol Med Sci 2013 Feb; 33(1):43-50
Benzene is an established leukotoxin and leukemogen in humans. We have previously reported that exposure of workers to benzene and to benzene metabolite hydroquinone in cultured cells induced DNA-dependent protein kinase catalytic subunit (DNA-PKcs) to mediate the cellular response to DNA double strand break (DSB) caused by DNA-damaging metabolites. In this study, we used a new, small molecule, a selective inhibitor of DNA-PKcs, 2-(morpholin-4-yl)-benzo[h]chomen-4-one (NU7026), as a probe to analyze the molecular events and pathways in hydroquinone-induced DNA DSB repair and apoptosis. Inhibition of DNA-PKcs by NU7026 markedly potentiated the apoptotic and growth inhibitory effects of hydroquinone in proerythroid leukemic K562 cells in a dose-dependent manner. Treatment with NU7026 did not alter the production of reactive oxygen species and oxidative stress by hydroquinone but repressed the protein level of DNA-PKcs and blocked the induction of the kinase mRNA and protein expression by hydroquinone. Moreover, hydroquinone increased the phosphorylation of Akt to activate Akt, whereas co-treatment with NU7026 prevented the activation of Akt by hydroquinone. Lastly, hydroquinone and NU7026 exhibited synergistic effects on promoting apoptosis by increasing the protein levels of pro-apoptotic proteins Bax and caspase-3 but decreasing the protein expression of anti-apoptotic protein Bcl-2. Taken together, the findings reveal a central role of DNA-PKcs in hydroquinone-induced hematotoxicity in which it coordinates DNA DSB repair, cell cycle progression, and apoptosis to regulate the response to hydroquinone-induced DNA damage.
Molecular-biology; Benzenes; Leukemogenesis; Leukocytes; Quinones; Metabolites; DNA-damage; Deoxyribonucleic-acids; Cellular-reactions; Cell-damage; Cell-alteration; Molecular-structure; Erythrocytes; Dose-response; Oxidative-metabolism; Oxidative-processes; Proteins; Toxins; Recombinant-DNA; Synergism; Hematology; Toxic-effects;
Author Keywords: benzene; DNA-dependent protein kinase catalytic subunit; 2-(morpholin-4-yl)-
benzo[h]chomen-4-one; Akt; DNA double strand break
YY Bi, Wuhan Univ, Sch Publ Hlth, Wuhan 430071, Peoples R China
Journal of Huazhong University of Science and Technology (Medical Sciences)