背景与目的:卵巢癌是妇科恶性肿瘤中发病率排名第3、致死率排名第1的疾病。卵巢癌的预后很差,这是由于大部分患者确诊时已处于晚期并且对铂类药物化疗易耐药,异常的DNA修复是导致铂类耐药的重要原因,针对性地干扰DNA损伤修复相关分子可...背景与目的:卵巢癌是妇科恶性肿瘤中发病率排名第3、致死率排名第1的疾病。卵巢癌的预后很差,这是由于大部分患者确诊时已处于晚期并且对铂类药物化疗易耐药,异常的DNA修复是导致铂类耐药的重要原因,针对性地干扰DNA损伤修复相关分子可能是提高铂类药物化疗敏感性的新手段。Ku86是参与非同源末端连接(non-homologous end joining,NHEJ)过程的一个关键分子,能够有效地修复DNA双链断裂(DNA double-strand break,DSB)。方法:使用免疫组织化学染色和细胞免疫荧光法检测Ku86在卵巢癌组织和细胞中的定位。使用RNAi技术下调Ku86,用顺铂处理后使用流式细胞术检测凋亡,使用细胞计数试剂盒(cell counting kit-8,CCK-8)法检测IC_(50)。使用蛋白质印迹法(Western blot)分别检测并分析Ku86与拓扑异构酶Ⅰ(topoisomeraseⅠ,TOP1)及COP9信号复合体的第5种成分(the fifth component of the COP9 signalosome,COPS5)的关系。结果:下调Ku86可以减少由于顺铂引起的细胞凋亡,降低卵巢癌细胞对于顺铂的敏感性。Ku86对顺铂在卵巢癌药物敏感性中的这种影响可能是通过调节TOP1和COPS5发挥作用的。结论:TOP1和COPS5都是与DNA损伤修复有关并能影响铂类药物化疗敏感性的重要分子,下调Ku86会使TOP1的表达增高和COPS5的表达减少。卵巢癌中与铂类药物敏感性有关的生物标志物之间有相关性,靶向Ku86的治疗可能是提高卵巢癌药物敏感性的有效策略。展开更多
Human polymorphonuclear leukocytes (PMN) have been reported to completely lack of DNA-dependent protein kinase (DNA-PK) which is composed of Ku protein and the catalytic subunit DNA-PKcs, needed for nonhomologous end-...Human polymorphonuclear leukocytes (PMN) have been reported to completely lack of DNA-dependent protein kinase (DNA-PK) which is composed of Ku protein and the catalytic subunit DNA-PKcs, needed for nonhomologous end-joining (NHEJ) of DNA double-strand breaks. Promyelocytic HL-60 cells express a variant form of Ku resulting in enhanced radiation sensitivity. This raises the question if low efficiency of NHEJ, instrumental for the cellular repair of oxidative damage, is a normal characteristic of myeloid differentiation. Here we confirmed the complete lack of DNAPK in P MN protein extracts, and the expression of the truncated Ku86 variant form in HL-60. However, this degradation of DNA-PK was shown to be due to a DNA-PK-degrading protease in PMN and HL-60. In addition, by using a protease-resistant whole cell assay, both Ku86 and DNA-PKcs could be demonstrated in PMN, suggesting the previously reported absence in PMN of DNA-PK to be an artefact. The levels of Ku86 and DNA-PKcs were much reduced in PMN, as compared with that of the lymphocytes, whereas HL-60 displayed a markedly elevated DNA-PK concentration.In conclusion, our findings provide evidence of reduced, not depleted expression of DNA-PK during the mature stages of myeloid differentiation.展开更多
文摘背景与目的:卵巢癌是妇科恶性肿瘤中发病率排名第3、致死率排名第1的疾病。卵巢癌的预后很差,这是由于大部分患者确诊时已处于晚期并且对铂类药物化疗易耐药,异常的DNA修复是导致铂类耐药的重要原因,针对性地干扰DNA损伤修复相关分子可能是提高铂类药物化疗敏感性的新手段。Ku86是参与非同源末端连接(non-homologous end joining,NHEJ)过程的一个关键分子,能够有效地修复DNA双链断裂(DNA double-strand break,DSB)。方法:使用免疫组织化学染色和细胞免疫荧光法检测Ku86在卵巢癌组织和细胞中的定位。使用RNAi技术下调Ku86,用顺铂处理后使用流式细胞术检测凋亡,使用细胞计数试剂盒(cell counting kit-8,CCK-8)法检测IC_(50)。使用蛋白质印迹法(Western blot)分别检测并分析Ku86与拓扑异构酶Ⅰ(topoisomeraseⅠ,TOP1)及COP9信号复合体的第5种成分(the fifth component of the COP9 signalosome,COPS5)的关系。结果:下调Ku86可以减少由于顺铂引起的细胞凋亡,降低卵巢癌细胞对于顺铂的敏感性。Ku86对顺铂在卵巢癌药物敏感性中的这种影响可能是通过调节TOP1和COPS5发挥作用的。结论:TOP1和COPS5都是与DNA损伤修复有关并能影响铂类药物化疗敏感性的重要分子,下调Ku86会使TOP1的表达增高和COPS5的表达减少。卵巢癌中与铂类药物敏感性有关的生物标志物之间有相关性,靶向Ku86的治疗可能是提高卵巢癌药物敏感性的有效策略。
文摘Human polymorphonuclear leukocytes (PMN) have been reported to completely lack of DNA-dependent protein kinase (DNA-PK) which is composed of Ku protein and the catalytic subunit DNA-PKcs, needed for nonhomologous end-joining (NHEJ) of DNA double-strand breaks. Promyelocytic HL-60 cells express a variant form of Ku resulting in enhanced radiation sensitivity. This raises the question if low efficiency of NHEJ, instrumental for the cellular repair of oxidative damage, is a normal characteristic of myeloid differentiation. Here we confirmed the complete lack of DNAPK in P MN protein extracts, and the expression of the truncated Ku86 variant form in HL-60. However, this degradation of DNA-PK was shown to be due to a DNA-PK-degrading protease in PMN and HL-60. In addition, by using a protease-resistant whole cell assay, both Ku86 and DNA-PKcs could be demonstrated in PMN, suggesting the previously reported absence in PMN of DNA-PK to be an artefact. The levels of Ku86 and DNA-PKcs were much reduced in PMN, as compared with that of the lymphocytes, whereas HL-60 displayed a markedly elevated DNA-PK concentration.In conclusion, our findings provide evidence of reduced, not depleted expression of DNA-PK during the mature stages of myeloid differentiation.
