Nakano K, Watney E, McDougall J K
Program in Cancer Biology, Fred Hutchinson Cancer Research Center, Seattle, Washington 19024, USA.
Am J Pathol. 1998 Sep;153(3):857-64. doi: 10.1016/S0002-9440(10)65627-1.
Telomerase, a ribonucleoprotein complex that includes the telomerase RNA component (hTR) and the telomerase catalytic subunit gene (hTERT) product, has been shown to be activated in the majority of cancer tissues and immortalized cells. To study telomerase activation during the progression of cervical cancer, the expression of hTR and hTERT RNAs in tissues of various stages of cervical cancer was analyzed using the in situ hybridization method and compared with proliferative activity as estimated by Ki-67 immunostaining. To test whether expression of these components is reflected in enzyme activity, we determined the levels of the RNAs in cervical cancer and normal tissues and in primary and immortal keratinocytes by reverse transcription-polymerase chain reaction and RNase protection assays and compared the results to telomerase activities as detected by telomeric repeat amplification protocol assay. In situ hybridization signals of hTR and hTERT were present not only in carcinoma tissues but also in normal epidermal layers. In many adenocarcinoma and fewer squamous cell carcinoma tissues, both signals were focally increased where high proliferative activity was present at the stages of dysplasia/metaplasia, in situ carcinoma, and invasive carcinoma. The level of bTERT, as quantitated by RNase protection assay, was not different between cancer and control tissues or immortal and a subset of primary keratinocytes and did not correlate with telomerase activity. These results indicate that expression of hTR and bTERT is up-regulated in at least a subset of neoplastic cells at an early stage of carcinogenesis and that unidentified factors, such as the modulation or coordination of its protein level with other products, may contribute to the activation of telomerase in cervical cancer.
端粒酶是一种核糖核蛋白复合物，包含端粒酶RNA组分（hTR）和端粒酶催化亚基基因（hTERT）产物，已证实在大多数癌组织和永生化细胞中被激活。为研究宫颈癌进展过程中端粒酶的激活情况，采用原位杂交方法分析了宫颈癌各阶段组织中hTR和hTERT RNA的表达，并与通过Ki-67免疫染色估计的增殖活性进行比较。为检测这些组分的表达是否反映在酶活性中，我们通过逆转录-聚合酶链反应和核糖核酸酶保护试验测定了宫颈癌组织、正常组织以及原代和永生化角质形成细胞中RNA的水平，并将结果与通过端粒重复序列扩增协议试验检测到的端粒酶活性进行比较。hTR和hTERT的原位杂交信号不仅存在于癌组织中，也存在于正常表皮层。在许多腺癌组织以及较少的鳞状细胞癌组织中，在发育异常/化生、原位癌和浸润癌阶段具有高增殖活性的部位，两种信号均局灶性增加。通过核糖核酸酶保护试验定量的hTERT水平在癌组织与对照组织之间，以及永生化和一部分原代角质形成细胞之间并无差异，且与端粒酶活性无关。这些结果表明，hTR和hTERT的表达在致癌作用早期至少一部分肿瘤细胞中上调，并且未明确的因素，如蛋白质水平与其他产物的调节或协调，可能有助于宫颈癌中端粒酶的激活。
