Expression of telomerase genes in thyroid carcinoma

Telomerase (T) is a ribonucleoprotein complex that includes the telomerase RNA component (hTR), telomerase associated protein (TP1) and the telomerase catalytic subunit (hTERT). Telomerase has been shown in stem cells and found to be activated in tumor tissues and immortalized cells. We wanted to test whether the expression of the telomerase complex subunits correlate with the enzyme activity in human thyroid tissue. Hence, we determined the expression of hTERT, hTR and TP1 mRNA by RT-PCR and compared the results to telomerase activity as detected by the telomeric repeat amplification protocol (TRAP) assay. Fifteen benign goiters (G), 11 follicular carcinomas (FTC) including 2 oncocytic follicular carcinomas (also called Hurthle cell carcinoma, oFTC), 12 papillary carcinomas (PTC) including 3 microcarcinomas (mPTC), and 12 undifferentiated anaplastic thyroid carcinomas (UTC) were investigated. Experienced pathologists performed histological and pTNM classification in each specimen. RT-PCR analysis revealed that TP1 was ubiquitously expressed in all G and carcinomas. hTR was expressed in 4 out of 15 G, in 2 out of 3 mPTC, in 5 out of 9 PTC, in 5 out of 9 FTC, in all oFTC and in 9 out of 12 UTC samples. Regarding all carcinomas, no statistically significant correlation was observed between hTR-expression and tumor stage, lymph node or distant metastasis. hTERT-expression was associated with malignancy and tumor stage. All mPTC and 13 out of 15 G did not express hTERT, whereas all samples of pT3-4 tumor stage of FTC, PTC, UTC and all oFTC were positive for hTERT. No telomerase activity could be detected in G. Telomerase activity in carcinoma was only measurable in tissues that expressed the catalytic subunit hTERT. Our data indicate that telomerase activity is up-regulated in neoplastic cells. In contrast to TP1 and hTR, hTERT and telomerase activity may be of help in identifying invasive tumors and may be additional markers for classification of benign goiter and malignant thyroid carcinoma.     

肺癌组织中端粒酶基因与端粒酶活性关系的研究

目的 探讨肺癌组织中端粒酶基因hTR、hTERT与端粒酶活性的表达是否与肺癌的发生发展有关，深入了解端粒酶基因对端粒酶活性的调控是在基因水平还是在转录水平。方法 采用TRAP－PCR和RT－PCR方法分别检测68例肺癌组织及相应癌旁肺组织中端粒酶活性、端粒酶基因hTR和hTERP的表达。结果 68例肺癌组织中端粒酶阳性率为79．4％（54／68）,hTR阳性率为98．5％（67／68）,hTERT阳性率为91．2％（62／68）。68例癌旁组织中无一例表达端粒酶阳性，但大多数癌旁组织均表达hTR(62/68,91.2%)，仅7例hTERT表达阳性（10．3％），与hTR相比，hTERT同端粒酶具有更高的一致性，其一致率为89．0％（121／136），而ThTR与端粒酶的一致率为43．4％（59／136）。结论 端粒酶的活性可能在肺癌发生发展中起重要的作用。hTR与hTERT可能是在转录后或翻译后水平对端粒酶进行调控的。     

Differential telomerase activity, expression of the telomerase catalytic sub-unit and telomerase-RNA in ovarian tumors.

Telomerase activity has been found in a variety of malignant tumors but only rarely in benign tumors or normal tissues. In this study, we investigated telomerase activation in 37 ovarian tumors, including benign, borderline and malignant neoplasms. Telomerase activity was detected using the telomeric repeat amplification protocol (TRAP) in 13/16 ovarian carcinomas, 9/10 borderline tumors and 3/11 cystadenomas/fibromas. mRNA expression of the putative human telomerase catalytic sub-unit gene (hTERT) was detected by RT-PCR in 14/15 ovarian carcinomas, 8/10 borderline tumors and 4/11 cystadenomas/fibromas. In situ hybridization was performed to evaluate telomerase-RNA (hTR) expression in the corresponding paraffin-embedded tumors. Variable expression levels of hTR were found over neoplastic tumor cells. The highest levels of hTR expression were found predominantly in ovarian carcinomas. Although the amount of telomerase activity varied, significantly high levels of telomerase activity were found predominantly in ovarian carcinomas. hTERT mRNA expression was closely associated with telomerase activity. These findings suggest that up-regulation of hTERT and hTR is important for telomerase activation during malignant-tumor progression. Telomerase activation might therefore be a valuable diagnostic parameter that could help to identify potentially progressive lesions. However, the diagnostic and therapeutic implications of telomerase activation need to be clarified in clinical trials. Int. J. Cancer (Pred. Oncol.) 84:426-431, 1999.     

端粒酶基因和抗凋亡基因bcl-2在肺组织中的表达研究

 目的　研究肺癌端粒酶基因和bcl 2的关系 ,以期阐明端粒酶基因及抗凋亡基因对端粒酶的调控机理。方法　采用TRAP、RT PCR及LSAB的方法研究了肺癌端粒酶活性、hTR、hTERT及bcl 2的表达。结果　 82 .3%的肺癌组织表达端粒酶阳性 ,38例癌组织中 ,34例表达hTR (89.4 % ) ,36例表达hTERT(94 .7% )。而在相应的癌旁组织中 ,34例表达hTR ,但只有 3例表达hTERT(7.8% )。结论　肺癌组织中具有较高的端粒酶活性 ,在肿瘤组织和正常组织中hTERT的表达有显著的差异 (P <0 .0 5 )。hTR在正常组织和肿瘤组织均有较高的表达 ,bcl 2的表达与端粒酶基因有着较高的相关性。     

人端粒酶催化亚基反义核酸对子宫内膜癌细胞的抑制作用

目的 探讨人端粒酶催化亚基(hTERT)基因反义寡核苷酸(AODN)对子宫内膜癌细胞系HEC-1A的生长抑制作用及作用机理。方法 采用四甲基偶氮唑蓝(MTT)法检测AODN对细胞增殖能力及细胞生长的影响;逆转录聚合酶链反应技术(RT-PCR)、定量端粒酶重复扩增法(TRAP)、Westerm blot蛋白免疫印迹法和凋亡相关酶活性测定检测反义核酸对hTERT基因转录、蛋白表达、细胞端粒酶活性以及凋亡相关酶活性的变化。结果 低浓度hTERT基因AODN能够下调HEC-1A细胞HTERT、mRNA含量,抑制细胞hTERT蛋白表达,下调端粒酶活性,并且激活凋亡相关酶Caspase-1和Caspase-3活性;其对细胞的生长抑制作用有明显的时效性和剂量依赖性。结论 hTERT基冈反义核酸能够抑制子宫内膜癌细胞的增殖能力,有望成为内膜癌治疗的新方向。     

Clinical utility of telomerase in cancer

This review will focus on the clinical utilities of telomerase for human cancer diagnosis. Much attention has been focused on detection of telomerase activity and its essential components (hTR and hTERT) in cancer and noncancerous tissues. Expression of hTR and hTERT is upregulated in almost all human malignant tumors but not in benign or normal tissues with the exception of germline cells, proliferative stem cells, activated lymphocytes, and certain benign tumors. Thus, telomerase is a useful marker for cancer diagnosis and in some instance as a prognostic indicator of outcome. Telomerase detection in cells derived from breast fine needle aspirates, bronchial washes, and pancreatic juices show high sensitivity and specificity for cancer detection. In tissue samples, the level of telomerase activity is a useful prognostic indicator in certain adult cancers such as gastric and colon cancers and in neuroblastomas. Immunohistochemical detection of hTERT will facilitate exact diagnosis of the telomerase positive cells and expand the application of telomerase in cancer diagnosis.