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 k...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.展开更多
AIM:To determine the expression of the catalytic subunit of DNA-dependent protein kinase(DNA-PKcs)and the Ku70/Ku80 heterodimer(Ku 70/80)in gastric carcinoma.METHODS:Gastric biopsies were obtained from 146gastric carc...AIM:To determine the expression of the catalytic subunit of DNA-dependent protein kinase(DNA-PKcs)and the Ku70/Ku80 heterodimer(Ku 70/80)in gastric carcinoma.METHODS:Gastric biopsies were obtained from 146gastric carcinoma patients[Helicobacter pylori(H.pylori)-negative:89 and H.pylori-positive:57]and 34from normal subjects(H.pylori-negative:16 and H.pylori-positive:18)via surgery and endoscopic detection from April 2011 to August 2012 at the First Affiliated Hospital of Nanchang University.Pathological diagnosis and classification were made according to the criteria of the World Health Organization and the updated Sydney system.An‘‘in-house’’rapid urease test and modified Giemsa staining were employed to detect H.pylori infection.The expression of DNA-PKcs and the Ku 70/80protein was detected by immunohistochemistry.RESULTS:Overall,the positive rates of both DNA-PKcs and Ku 70/80 were significantly increased in gastric cancer(χ2=133.04,P<0.001 for DNA-PKcs andχ2=13.06,P<0.01 for Ku)compared with normal gastric mucosa.There was hardly any detectable expression of DNA-PKcs in normal gastric mucosa,and the positive rate of DNA-PKcs protein expression in patients with a normal gastric mucosa was 0%(0/34),whereas the rate in gastric cancer(GC)was 93.8%(137/146).The difference between the two groups was statistically significant.Additionally,the positive rate of Ku 70/80 was79.4%(27/34)in normal gastric mucosa and 96.6%(141/146)in gastric cancer.The DNA-PKcs protein level was significantly increased in gastric cancer(MannWhitney U=39.00,P<0.001),compared with normal gastric mucosa.In addition,there was a significant difference in the expression of Ku 70/80(Mann-Whitney U=1117.00,P<0.001)between gastric cancer and normal gastric mucosa.There was also a significant difference in Ku70/80 protein expression between GC patients with and without H.pylori infection(P<0.05).Spearman analysis showed a negative correlation between tumor differentiation and DNA-PKcs expression(r=-0.447,P<0.05).Moreover,Ku70/80 expression was negatively correlated with both clinical stage(r=-0.189,P<0.05)and H.pylori colonization(r=-0.168,P<0.05).CONCLUSION:Overall,this research demonstrated that enhanced DNA-PKcs and Ku 70/80 expression may be closely associated with gastric carcinoma.展开更多
Pim kinases contribute to tumor formation and development of lymphoma,which shows enhanced DNA replication,DNA recombination and repair.Endothelial cells (ECs) express all the three members of Pim kinase gene family.W...Pim kinases contribute to tumor formation and development of lymphoma,which shows enhanced DNA replication,DNA recombination and repair.Endothelial cells (ECs) express all the three members of Pim kinase gene family.We hypothesized that DNA repair gene would regulate Pim ex-pression in ECs.Human umbilical vein endothelial cells (HUVECs) were isolated and maintained in M199 culture medium.The cellular distribution of Pim-3 in ECs was determined by immunofluorescent staining.The siRNA fragments were synthesized and transfected by using Lipofectamine LTX.The total cellular RNA was extracted from the cells by using Trizol reagent.cDNAs were quantified by semi-quantity PCR.The effects of LY294002 and wortmannin on RNA stability in ECs were also ex-amined.Our data showed that LY294002 and wortmannin,phosphatidylinositol 3-kinase (PI3K) and PI3K-like kinase inhibitors,increased Pim mRNA expression in ECs without altering the mRNA stabil-ity.RNA interference (RNAi) targeting DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and ataxia telangiectasia mutated (ATM) increased mRNA expression of Pim-3 and Pim-1,respectively.Silencing of Akt decreased Pim-1 instead of Pm-2 and Pim-3 gene expression in ECs.But etoposide,a nucleoside analogue,which could activate DNA-PKcs and ATM,increased Pim expression in ECs.Our study indicates that the expression of Pim kinases is physiologically related to DNA-PKcs and ATM in ECs.展开更多
目的观察联合抑制聚腺苷酸二磷酸核糖转移酶-1[poly(ADP-ribose)polymerase-1,PARP-1]及DNA依赖蛋白激酶催化亚单位(catalytic sunbunit of the DNA-dependent protein kinase,DNA-PKcs)对依托泊苷(etoposide,VP-16)作用于急性髓系白血...目的观察联合抑制聚腺苷酸二磷酸核糖转移酶-1[poly(ADP-ribose)polymerase-1,PARP-1]及DNA依赖蛋白激酶催化亚单位(catalytic sunbunit of the DNA-dependent protein kinase,DNA-PKcs)对依托泊苷(etoposide,VP-16)作用于急性髓系白血病KG-1α细胞的影响。方法分别用特异性抑制剂奥拉帕尼(Olaparib,OLA)和Nu7441(NU)抑制PARP-1、DNA-PKcs。将KG-1α细胞设置成对照组、模型组、PARP-1抑制组(PARP-1 inhibition,VP-16+OLA)、DNA-PKcs抑制组(DNA-PKcs inhibition,VP-16+NU)、联合抑制组(combined inhibition,VP-16+OLA+NU)。用四甲基偶氮唑蓝(MTT)法体外检测联合用药对KG-1α细胞增殖抑制的影响;用高内涵荧光成像检测分析不同处理组的γ-H2AX在DNA双链断裂断裂位点的募集情况;用蛋白质印迹法检测细胞凋亡相关蛋白Cleaved caspase-3和Cleaved PARP的表达情况。结果对照组、模型组、PARP-1抑制组、DNA-PKcs抑制组和联合抑制组的增殖抑制率分别为(1.16±1.45)%,(23.88±3.15)%,(28.12±2.28)%,(17.21±0.89)%和(60.72±4.38)%;γ-H2AX阳性细胞百分比分别为γ-H2 AX阳性细胞百分比分别为(1.24±0.07)%,(22.51±2.24)%,(24.55±3.29)%,(23.28±2.48)%和(40.55±1.61)%;Cleaved Caspase-3蛋白相对表达量分别为0.16±0.10,0.61±0.30,1.15±0.64,1.11±0.31和1.72±1.03;Cleaved PARP蛋白相对表达量分别为1.23±0.09,1.45±0.55,2.03±0.84,2.08±0.41和2.66±0.95。模型组分别与对照组、联合抑制组比较,差异均有统计学意义(均P<0.05)。结论联合抑制PARP-1及DNA-PKcs能够在体外增加KG-1α细胞对依托泊苷的敏感性。展开更多
文摘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.
基金Supported by The National natural science foundation of China,No.81270479
文摘AIM:To determine the expression of the catalytic subunit of DNA-dependent protein kinase(DNA-PKcs)and the Ku70/Ku80 heterodimer(Ku 70/80)in gastric carcinoma.METHODS:Gastric biopsies were obtained from 146gastric carcinoma patients[Helicobacter pylori(H.pylori)-negative:89 and H.pylori-positive:57]and 34from normal subjects(H.pylori-negative:16 and H.pylori-positive:18)via surgery and endoscopic detection from April 2011 to August 2012 at the First Affiliated Hospital of Nanchang University.Pathological diagnosis and classification were made according to the criteria of the World Health Organization and the updated Sydney system.An‘‘in-house’’rapid urease test and modified Giemsa staining were employed to detect H.pylori infection.The expression of DNA-PKcs and the Ku 70/80protein was detected by immunohistochemistry.RESULTS:Overall,the positive rates of both DNA-PKcs and Ku 70/80 were significantly increased in gastric cancer(χ2=133.04,P<0.001 for DNA-PKcs andχ2=13.06,P<0.01 for Ku)compared with normal gastric mucosa.There was hardly any detectable expression of DNA-PKcs in normal gastric mucosa,and the positive rate of DNA-PKcs protein expression in patients with a normal gastric mucosa was 0%(0/34),whereas the rate in gastric cancer(GC)was 93.8%(137/146).The difference between the two groups was statistically significant.Additionally,the positive rate of Ku 70/80 was79.4%(27/34)in normal gastric mucosa and 96.6%(141/146)in gastric cancer.The DNA-PKcs protein level was significantly increased in gastric cancer(MannWhitney U=39.00,P<0.001),compared with normal gastric mucosa.In addition,there was a significant difference in the expression of Ku 70/80(Mann-Whitney U=1117.00,P<0.001)between gastric cancer and normal gastric mucosa.There was also a significant difference in Ku70/80 protein expression between GC patients with and without H.pylori infection(P<0.05).Spearman analysis showed a negative correlation between tumor differentiation and DNA-PKcs expression(r=-0.447,P<0.05).Moreover,Ku70/80 expression was negatively correlated with both clinical stage(r=-0.189,P<0.05)and H.pylori colonization(r=-0.168,P<0.05).CONCLUSION:Overall,this research demonstrated that enhanced DNA-PKcs and Ku 70/80 expression may be closely associated with gastric carcinoma.
基金supported by grants from the National Natural Science Foundation of China (No. 30900631)Hubei Provincial Department of Education (No. Q20102101 andD20082406)
文摘Pim kinases contribute to tumor formation and development of lymphoma,which shows enhanced DNA replication,DNA recombination and repair.Endothelial cells (ECs) express all the three members of Pim kinase gene family.We hypothesized that DNA repair gene would regulate Pim ex-pression in ECs.Human umbilical vein endothelial cells (HUVECs) were isolated and maintained in M199 culture medium.The cellular distribution of Pim-3 in ECs was determined by immunofluorescent staining.The siRNA fragments were synthesized and transfected by using Lipofectamine LTX.The total cellular RNA was extracted from the cells by using Trizol reagent.cDNAs were quantified by semi-quantity PCR.The effects of LY294002 and wortmannin on RNA stability in ECs were also ex-amined.Our data showed that LY294002 and wortmannin,phosphatidylinositol 3-kinase (PI3K) and PI3K-like kinase inhibitors,increased Pim mRNA expression in ECs without altering the mRNA stabil-ity.RNA interference (RNAi) targeting DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and ataxia telangiectasia mutated (ATM) increased mRNA expression of Pim-3 and Pim-1,respectively.Silencing of Akt decreased Pim-1 instead of Pm-2 and Pim-3 gene expression in ECs.But etoposide,a nucleoside analogue,which could activate DNA-PKcs and ATM,increased Pim expression in ECs.Our study indicates that the expression of Pim kinases is physiologically related to DNA-PKcs and ATM in ECs.
文摘目的观察联合抑制聚腺苷酸二磷酸核糖转移酶-1[poly(ADP-ribose)polymerase-1,PARP-1]及DNA依赖蛋白激酶催化亚单位(catalytic sunbunit of the DNA-dependent protein kinase,DNA-PKcs)对依托泊苷(etoposide,VP-16)作用于急性髓系白血病KG-1α细胞的影响。方法分别用特异性抑制剂奥拉帕尼(Olaparib,OLA)和Nu7441(NU)抑制PARP-1、DNA-PKcs。将KG-1α细胞设置成对照组、模型组、PARP-1抑制组(PARP-1 inhibition,VP-16+OLA)、DNA-PKcs抑制组(DNA-PKcs inhibition,VP-16+NU)、联合抑制组(combined inhibition,VP-16+OLA+NU)。用四甲基偶氮唑蓝(MTT)法体外检测联合用药对KG-1α细胞增殖抑制的影响;用高内涵荧光成像检测分析不同处理组的γ-H2AX在DNA双链断裂断裂位点的募集情况;用蛋白质印迹法检测细胞凋亡相关蛋白Cleaved caspase-3和Cleaved PARP的表达情况。结果对照组、模型组、PARP-1抑制组、DNA-PKcs抑制组和联合抑制组的增殖抑制率分别为(1.16±1.45)%,(23.88±3.15)%,(28.12±2.28)%,(17.21±0.89)%和(60.72±4.38)%;γ-H2AX阳性细胞百分比分别为γ-H2 AX阳性细胞百分比分别为(1.24±0.07)%,(22.51±2.24)%,(24.55±3.29)%,(23.28±2.48)%和(40.55±1.61)%;Cleaved Caspase-3蛋白相对表达量分别为0.16±0.10,0.61±0.30,1.15±0.64,1.11±0.31和1.72±1.03;Cleaved PARP蛋白相对表达量分别为1.23±0.09,1.45±0.55,2.03±0.84,2.08±0.41和2.66±0.95。模型组分别与对照组、联合抑制组比较,差异均有统计学意义(均P<0.05)。结论联合抑制PARP-1及DNA-PKcs能够在体外增加KG-1α细胞对依托泊苷的敏感性。
