Takakura M, Kyo S, Kanaya T, Tanaka M, Inoue M
Department of Obstetrics and Gynecology, School of Medicine, Kanazawa University, Ishikawa, Japan.
Cancer Res. 1998 Apr 1;58(7):1558-61.
Activation of telomerase and stabilization of telomeres are thought to be required for both cellular immortality and oncogenesis. Three major components of human telomerase, human telomerase RNA (hTR), telomerase-associated protein (TP1/TLP1), and human telomerase catalytic subunit (hTRT/hEST2), have been identified recently. However, it remains unclear what roles these subunits play in the regulation of telomerase activity. In the present study, a total of 25 cervical cancers and 14 normal cervices as well as various cell lines derived from cervical cancer were examined for the expression of hTR, TP1 mRNA, and hTRT mRNA, and the correlations between expression of these and telomerase activity were evaluated in 23 cancers and 14 normal cervices. Reverse transcription-PCR analysis revealed that hTR and TP1 mRNA were commonly expressed in cancers and noncancerous tissues. However, hTRT mRNA was observed only in cervical cancers and cell lines, and more than 80% of cervical cancers expressed it, whereas neither normal cervical tissues nor normal primary fibroblast cells did. There was a strong correlation of telomerase activity with hTRT mRNA expression but not with TP1 or hTR expression. Cervical exfoliated cells were subjected to reverse transcription-PCR analysis for detection of hTRT mRNA, and approximately 70% of cervical cancers were positive for such expression. These findings provide strong evidence that expression of hTRT is a rate-limiting determinant of the enzymatic activity of human telomerase and that up-regulation of hTRT expression may play a critical role in human carcinogenesis. Our findings also indicate that detection of hTRT mRNA is useful for cytological screening for cervical cancer.
端粒酶的激活和端粒的稳定被认为是细胞永生化和肿瘤发生所必需的。人类端粒酶的三个主要成分，即人类端粒酶RNA（hTR）、端粒酶相关蛋白（TP1/TLP1）和人类端粒酶催化亚基（hTRT/hEST2），最近已被鉴定出来。然而，这些亚基在端粒酶活性调节中所起的作用仍不清楚。在本研究中，对25例宫颈癌、14例正常宫颈组织以及源自宫颈癌的各种细胞系进行了hTR、TP1 mRNA和hTRT mRNA表达的检测，并在23例癌症和14例正常宫颈组织中评估了这些表达与端粒酶活性之间的相关性。逆转录-聚合酶链反应分析显示，hTR和TP1 mRNA在癌症组织和非癌组织中均普遍表达。然而，hTRT mRNA仅在宫颈癌和细胞系中观察到，超过80%的宫颈癌表达该基因，而正常宫颈组织和正常原代成纤维细胞均未表达。端粒酶活性与hTRT mRNA表达呈强相关，而与TP1或hTR表达无关。对宫颈脱落细胞进行逆转录-聚合酶链反应分析以检测hTRT mRNA，约70%的宫颈癌对此种表达呈阳性。这些发现提供了强有力的证据，表明hTRT的表达是人类端粒酶酶活性的限速决定因素，并且hTRT表达的上调可能在人类致癌过程中起关键作用。我们的发现还表明，检测hTRT mRNA对宫颈癌的细胞学筛查有用。
