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.     

鼻咽癌组织端粒酶各组分基因表达的研究

目的：探讨端粒酶各组分基因在鼻咽癌（nasopharynegal carcinoma,NPC)组织及鼻咽慢性炎症粘膜（chronic inflammation of nasopharyngeal epithelium,CINE)组织中的表达情况。方法：利用RT-PCR方法检测鼻咽癌组织及鼻咽慢性炎症粘膜组织端粒酶各组分基因（hTR、TP1mRNA和hRNA)的表达情况。方法：利用RT-PCR方法检测鼻咽癌组织及鼻咽慢性炎症粘膜组织端粒酶各组分基因（hTR、TP1mRNA和hTERTmRNA)的表达。结果：43例NPC组织中,hTR、TP1mRNA和hTERTmRNA表达阳性率分别为90.7%、88.4%和16例CINE组织中,hTR、TP1 RNA和hTERTmRNAmRNA表达阳性率为87.5%、87.5%和0%;仅hTERTmRNA在鼻咽癌组织中的表达显著高于鼻咽慢性炎症粘膜组织中的表达,而hTR或TP1mRNA在鼻咽癌组织中的表达和鼻咽慢性炎症粘膜组织中的表达。结论：hTERTmRNA可能在端粒酶活性调节中起重工作用;hTERTmRNA的表达水平,可作为鼻咽癌诊断指标之一。     

Telomerase in relation to clinicopathologic prognostic factors and survival in cervical cancer

We investigated, in cervical cancer, the relation between telomerase activity, telomerase RNA (hTR) and mRNA of the catalytic subunit of telomerase, hTERT, with "classic" clinicopathological factors as well as survival. Frozen specimens were obtained from 107 consecutive patients with cervical cancer, treated with surgery or radiotherapy with or without chemotherapy. Telomerase activity was determined with fluorescence-based TRAP and hTR and hTERT with semi-quantitative RT-PCR. Eight normal cervical specimens served as controls. Analysis of prognostic factors and survival was limited to early-stage patients, treated primarily with radical hysterectomy. Telomerase activity was not detected in normal cervices and was present in 85 of 107 (79%) cervical cancers (p < 0.001). hTR was detected in all normal cervices and cervical cancers, while hTERT mRNA was detected in 1 of 8 (13%) normal cervices and in 83 of 104 (80%) cervical cancers (p < 0.001). In contrast to semi-quantitative hTR expression levels, semi-quantitative hTERT mRNA levels were related to telomerase activity levels (p < 0.01). In all patients, telomerase activity levels were related to differentiation grade (p < 0.05) but not to stage and histotype. In early-stage patients, telomerase activity, hTR and hTERT were not related to tumor volume, vascular invasion or presence of metastatic lymph nodes. Tumor volume, vascular invasion and presence of metastatic lymph nodes were related to (progression-free) survival, while telomerase activity and its subunits were not. Frequent up-regulation of telomerase activity and hTERT mRNA is especially observed in cervical cancers, while hTR is also detected in normal cervices. Telomerase is not applicable as a prognostic factor in early-stage cervical cancer patients.     

Expression of Human Telomerase RNA Is an Early Event of Stomach Carcinogenesis

Expression of human telomerase RNA (hTR) and telomerase activity in gastric cancer and corresponding non-cancerous mucosa were studied. Telomerase activity was detected in 23 (88%) of 26 carcinoma tissues. Although all tumor specimens and non-cancerous mucosa expressed various levels of hTR, 21 (81%) of 26 cases expressed hTR at a higher level in the tumor than that in the corresponding mucosa. All 8 gastric carcinoma cell lines also expressed hTR at high levels. Nine (35%) of 26 non-cancerous mucosa showed telomerase activity and all of them contained intestinal metaplasia. The incidence of telomerase-positive mucosa in grade 2 intestinal metaplasia was significantly higher than that in grade 0 or grade 1 intestinal metaplasia, whereas hTR overexpression was found in grade 0 or grade 1 intestinal metaplasia as well as grade 2 intestinal metaplasia. The degree of Heticobacter pylori infection increased in parallel with the level of hTR expression and telomerase positivity. These results overall suggest that Helicobacter pylori infection may he a strong trigger for hTR overexpression in intestinal metaplasia, and this may lead to telomerase reactivation.     

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。     

Detection of telomerase RNA in the plasma of patients with breast cancer, malignant melanoma or thyroid cancer

The crucial step in cellular immortalisation seems to be the activation of telomerase, the enzyme that synthesizes telomere repeat ending sequences. Since the telomerase activity has been detected in almost all types of cancer tissue it has been proposed as new reliable tumor marker. This study was conducted to evaluate the significance of appearance of circulating RNA for telomerase subunits hTR and hTERT in the plasma of cancer patients. Seven healthy volunteers, 25 primary breast cancer patients (stage I-III), 29 patients with advanced malignant melanoma (stage III-IV), and 4 patients with advanced thyroid cancer (stage III-IV) were included in the study. The total RNA was extracted from plasma samples, reverse transcribed to cDNAs, and specific cDNAs for hTR and hTERT were amplified by semi-nested PCR. In healthy volunteers, the control GAPDH was positive in all, hTR was positive in 3 cases, and hTERT was negative in all 7 tested cases. Among 25 breast cancer patients, hTR was positive in 23, and hTERT in 12 patients. Two cases, that were hTR and hTERT negative, were at the same time negative also for GAPDH. Of the 29 patients with malignant melanoma, 24 were positive for hTR, and 17 for hTERT. Again, the 5 patients that were negative for hTR and hTERT, were negative also for the control GAPDH. In all plasma samples from thyroid cancer patients, hTR and hTERT were positive. In conclusion, the RT-PCR followed by semi-nested PCR is a highly sensitive method for detection of circulating RNA in the plasma. Among the telomerase subunits, only hTERT could serve as an unspecific tumor marker in the plasma of cancer patients.     

Proteome analysis identified maspin as a special feature of papillary thyroid carcinoma

This study aimed at investigating new mechanisms of carcinogenesis in thyroid cancer at the molecular level and at finding potential protein markers involved in the initiation of the different histological subtypes. For this, we performed differential proteome analysis on primary cultured thyrocytes (PT) and transformed thyrocytes (TT) derived from 238Pu alpha-particle irradiation using 2-dimensional electrophoresis (2-DE) and peptide mass fingerprinting (PMF) with matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF MS). Image analysis showed that one protein was very strongly expressed in TT; 55 proteins were weaker, different in intensity, including 26 spots that were increased in PT, and 29 spots were decreased. The hot spot was identified as maspin, a unique member of the serpin family considered to be a class II tumor suppressor gene. To clarify the role of maspin in thyroid carcinogenesis we searched for protein expression in 20 normal (tumor-free) tissues, as well as in 20 follicular adenomas (FAD), 20 papillary carcinomas (PTC), 20 follicular carcinomas (FTC), 20 poorly differentiated carcinomas (PDTC), and 20 undifferentiated carcinomas (UTC). Maspin protein expression was detectable in none of the cases of normal tumor-free thyroid tissue, nor in FAD, FTC, PDTC and UTC. In contrast 14 of 20 PTC (70%) showed a moderate or strong cytoplasmic staining; 4 of these 14 cases had a moderate cytoplasmic and nuclear staining. In conclusion, we hypothesize that maspin protein expression is a special feature in the cascade of PTC genesis and that the way of initiating PTC is different from other thyroid carcinoma types.