Inhibition of DNA-dependent Protein Kinase Catalytic Subunit by Small Molecule Inhibitor NU7026 Sensitizes Human Leukemic K562 Cells to Benzene Metabolite-induced Apoptosis

• Published in: Journal of Huazhong University of Science and Technology. Medical sciences Vol. 33; no. 1; pp. 43 - 50
• Main Author: 游浩 孔萌萌 王立萍 肖潇 廖汉林 毕卓悦 燕虹 王红 汪春红 马强 刘燕群 毕勇毅
• Format: Journal Article
• Language: English
• Published: Heidelberg Huazhong University of Science and Technology 01.02.2013; School of Medicine, Jianghan University, Wuhan 430056, China%School of Public Health,Wuhan University, Wuhan 430071, China%School of Pharmaceutical Science, Wuhan University, Wuhan 430071, China; School of Public Health,Wuhan University, Wuhan 430071, China
• Subjects: Apoptosis - drug effects; Apoptosis - physiology; Benzene - toxicity; Catalysis; Chromones - pharmacology; DNA Damage - drug effects; DNA Damage - genetics; DNA Repair - drug effects; DNA Repair - physiology; DNA-Activated Protein Kinase - antagonists & inhibitors; DNA-Activated Protein Kinase - metabolism; DNA依赖蛋白激酶; Humans; K562 Cells; K562细胞; Medicine; Medicine & Public Health; Morpholines - pharmacology; Protein Subunits; 催化亚单位; 对苯二酚; 小分子; 白血病; 细胞凋亡; 选择性抑制剂; DNA-dependent protein kinase catalytic subunit; 2-(morpholin-4-yl)-benzo[h]chomen-4-one; Akt; DNA double strand break; benzene
• ISSN: 1672-0733; 1993-1352
• DOI: 10.1007/s11596-013-1069-z

Benzene is an established leukotoxin and leukemogen in humans. We have previously re- ported 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 phos- phorylation 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 apop- tosis 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.