中文摘要：

目的：探讨人胃腺癌细胞系SGC7901及其多药耐药亚系SGC7901／VCR中端粒酶活性变化及其机制，为胃癌多药耐药机制研究提供新靶点。方法：采用TRAP银染方法检测SGC7901和SGC7901／VCR中端粒酶的活性；应用反转录聚合酶链反应（RT—PCR）技术检测SGC7901和SGC7901／VCR中端粒酶hTERT、Madl及c—myctuRNA的表达；将hTERT启动子构建的报告基因质粒（pGL3B—TRTP），转染入SGC7901和SGC7901／VCR中，应用双荧光素酶报告基因检测系统（Dual—Luciferasereporterassaysystem）检测端粒酶hTERT启动子的活性。结果：SGC7901／VCR细胞中的端粒酶活性及端粒酶hTERTmRNA表达均显著高于SGC7901细胞，且SGC7901／VCR中hTERT启动子的活性显著高于SGC7901，在SGC7901／VCR中捡测到c—mycmRNA的表达，但未检测到MadlmRNA的表达，而在SGC7901细胞中分别检测到MadlmRNA和c—mycmRNA的表达，且SGC7901细胞中c—mycmRNA的表达也高于SGC7901／VCR。结论：端粒酶活性及端粒酶hTERT转录水平升高与胃癌细胞的多药耐药性密切相关，转录因子Madl／c—myc的表达高低是其作用机制之一。

英文摘要：

Objective： To investigate telomerase activity and telomerase expression in the human gastric carcinoma cell line SGC7901 and its multi-drug resistant subeuhured cell line SGC7901/VCR, and to search for a new target within the drug-resistance mechanism of the gastric carcinoma cell line. Methods： Silver staining TRAP（telomeric repeat amplification protocol） assay was used to detect telomerase activity. Semi-quantitative reverse transcriptase PCR was employed to detect hTERT, Madl and c-Myc mRNA expression. Plasmid （pGL3B-TRTP） was transfected into SGC7901/VCR and SGC7901. Expression of the reporter gene in the cell lysates was assayed by a dual luciferase reporter assay system. Results： Both telomerase activity and telomerase hTERT mRNA expression in SGC7901/VCR cells were higher than those in SGC7901cells. hTERT promoter activity was significantly higher in SGC7901/ VCR than in SGC7901. c-Myc mRNA expression was detected in SGC7901/VCR, but Madl mRNA was not, In SGC7901, both c-Myc and Madl mRNA expression could be detected and c-Myc mRNA expression was higher than that in SGC7901/VCR. Conclusion： Telomerase activity in SGC7901/VCR was higher than that in SGC7901, and the high level of telomerase hTERT gene transcription and ex-pression in SGC7901/VCR was correlated with drug-resistance. Madl and c-Myc expression may contribute to hTERT transcription and telomerase activity.