中文摘要：

背景与目的 端粒酶在多种肿瘤中均有表达，并且可能参与肿瘤耐药。本研究的目的是观察端粒酶催化亚基脱氧核酶对A549／DDP耐药细胞生长的抑制作用，探讨端粒酶作为耐药肿瘤细胞治疗新靶标的可能性。方法 合成针对端粒酶催化亚基mRNA的脱氧核酶，脱氧核酶体外切割端粒酶催化亚基mRNA片段。采用TRAP法检测转染脱氧核酶的A549／DDP细胞端粒酶活性，采用MTT法分别检测脂质体转染脱氧核酶、顺铂及其混合物对A549／DDP细胞生长的作用。结果 端粒酶脱氧核酶在体外可以切割端粒酶催化亚基RNA，并具有剂量依赖关系；转染脱氧核酶可抑制A549／DDP细胞端粒酶活性；端粒酶脱氧核酶0．25umol／L作用72h，A549／DDP耐药细胞生长抑制率可达32．9％，同3mg／L顺铂联合使用时抑制率可达60．5％，两者相互作用指数CDI=0、9。结论 端粒酶催化亚基脱氧核酶可明显降低端粒酶活性，显著抑制人肺腺癌A549／DDP耐药细胞的生长，并且与化疗药物顺铂有协同作用，提示端粒酶有可能成为耐药肿瘤细胞新的治疗靶标。

英文摘要：

Background and objective Telomerase expresses in many cancers and may contribute to drug-resistance. The aim of this study is to observe the effect of telomerase reverse transcriptase （hTERT） DNAzyme on growth of A549/DDP cells and to explore the possibility of telomerase as a new target in treatment of drug resistance for lung cancer. Methods An hTERT DNAzyme was composed. Telomerase activity was measured by telomeric repeat amplification protocol （TRAP） modified from Kim＇s method. MTT was used to show the influence of hTERT DNAzyme and cisplatin on A549/DDP cells. Results The telomerase activity of A549/DDP cells was down regulated by hTERT DNAzyme in a dose-dependent manner. The growth inhibition rate of A549/DDP cells was 32.9G by hTERT DNAzyme of 0.25μmol/L, and 60.5% by hTERT DNAzyme combined with 3 mg/L cisplatin. The CDI of hTERT DNAzyme and cisplatin was 0. 9. Conclusion hTERT DNAzyme can inhibit the growth of A549/DDP cells and has a synergistic effect with cis platin. It is suggested that telomerasemay bea new target in treatment of drug-resistant lung cancer cells.