Telomerase Activity In Tissues Research Articles

Detection of Urothelial Bladder Cancer Based on Urine and Tissue Telomerase Activity Measured by Novel RT-TRAP-2PCR Method.

Purpose: To assess the diagnostic performance of urine telomerase activity (TA) in detecting bladder cancer (BCa) using the modified Telomeric Repeat Amplification Protocol (TRAP) and the Real Time Telomeric Repeat Amplification Protocol with double Polymerase Chain Reaction (RT-TRAP-2PCR). Methods: In this case-control study, matching urine (in the pre- and post-surgical period) and tissue samples from 68 patients with BCa were assessed for TA. As a control, 45 urine samples were examined from non-BCa patients. TA levels were measured using TRAP and RT-TRAP-2 PCR methods. Results: Preoperative urinary TA was elevated in 64 (94.1%) of the 68 BCa patients. Urine TA was undetectable in 44 control patients, while TA was detected in one patient with histologically verified cystitis. Sensitivity for BCa detection of 94.1% and specificity of 97.8% were observed for urinary TA, while tissue TA had 100% sensitivity and 97.8% specificity. Both urine and tissue TA levels were not significantly higher in patients with muscle-invasive disease compared to those with non-muscle invasive BCa (p > 0.05). Urine and tissue TA levels were not associated with higher tumor grade, stage, and number of tumors (p > 0.05). However, the association was found between higher urinary and tissue TA levels with tumor size ≥ 3 cm (p = 0.02 and p = 0.01, respectively). During the first postoperative year, 17 BCa patients experienced disease recurrence, and urinary TA was present in 14 (82.4%) of these patients. The sensitivity and specificity of urinary TA levels for BCa recurrence in patients with non-muscle invasive bladder cancer (NMIBC) during follow-up were 82% and 94.4%, respectively. Conclusions: This pilot study demonstrates a high diagnostic performance of urinary and tissue TA levels measured by a new RT-TRAP-2PCR method for detecting and monitoring BCa. Additionally, the association was found between higher urinary and tissue TA levels with tumor size ≥ 3 cm; however, higher TA levels failed for significant correlation with advanced tumor stage and grade. Our study could serve as a benchmark for the evaluation of novel biomarkers using the RT-TRAP-2PCR method.

Impaired telomerase activity hinders proliferation and in vitro transformation of Penaeus monodon lymphoid cells.

Retaining terminal transferase activity of telomerase, the ribonucleoprotein enzyme which add telomeric repeats on chromosome end is thought to be required to prevent cellular ageing. Additionally, telomerase considered as a marker for cell proliferation and immortalization in eukaryotes. We examined telomerase activity in tissues and lymphoid cell culture of Penaeus monodon. Along with telomerase activity, telomere repeats and an attempt on identification of telomerase reverse transcriptase (PmTERT) were made. Telomeric repeat amplification protocol revealed that telomerase-dependent telomeric lengthening has been taking place in P. monodon and the adult tissues were retaining this capacity throughout their lifespan with the highest activity in ovary, testis and lymphoid organ. However, telomerase activity could not be detected in lymphoid cells in culture. The canonical telomeric repeats added by telomerase of lymphoid tissue extract were identified as TTAGG, but pentameric repeats GGTTA and AGGTT were also added by the telomerase. PmTERT protein sequence (partial) shared 100% identity with the TERT sequence of Daphnia pulex, 27% sequence identity with Purple sea urchin and 24-25% with Zebra fish. Undetectable telomerase activity in lymphoid cell culture supports the hypothesis that the inadequate telomerase activity or gene expression may be a reason that prevents neoplastic transformation and spontaneous immortalization of the cells in vitro. Thus, it is envisaged that telomerase activation in lymphoid cells may surmount cellular ageing for in vitro transformation and cell line establishment.

Developmental silencing of the AtTERT gene is associated with increased H3K27me3 loading and maintenance of its euchromatic environment

Telomerase, an enzyme responsible for the maintenance of linear chromosome ends, is precisely regulated during plant development. In animals, involvement of the epigenetic state of the telomerase reverse transcriptase (TERT) gene in the complex regulation of telomerase activity has been reported. To reveal whether epigenetic mechanisms participate in the regulation of plant telomerase, the relationship between telomerase activity in tissues of Arabidopsis thaliana and DNA methylation and histone modifications in the A. thaliana TERT (AtTERT) upstream region was studied. As expected, a gradual decrease of telomerase activity during leaf maturation was observed. A different pattern with a more progressive loss of telomerase activity and AtTERT transcription during leaf development was revealed in MET1 gene-knockout mutants. Analysis of DNA methylation in the AtTERT upstream region showed low levels of methylated cytosines without notable differences between telomerase-positive and telomerase-negative wild-type tissues. Surprisingly, a high level of CG methylation was found in the AtTERT coding region, although this type of methylation is a characteristic attribute of constitutively expressed genes. Analysis of chromatin modifications in the AtTERT upstream region and in exon 5 showed increased loading of the H3K27me3 mark in the telomerase-negative mature leaf compared to telomerase-positive seedlings, whereas H3K4me3, H3K9Ac, and H3K9me2 were approximately at the same level. Consistently, the chromatin structure of the AtTERT gene was maintained. These results are discussed in the context of the general involvement of epigenetic mechanisms in the regulation of gene expression and with respect to similar studies performed in animal models.

Expression of telomerase & its significance in the diagnosis of pancreatic cancer

Pancreatic cancer has one of the worst prognoses among all types of cancers. The survival rate is less than 5 per cent; this is due to difficulty in diagnosing at an early stage. Despite the improvements in diagnostic imaging techniques such as computed tomography, magnetic resonance imaging, etc., the early diagnosis of pancreatic cancer is still difficult. Alternative methods of diagnosing pancreatic cancer at an early stage are presently been explored. The detection of telomerase activity has been proposed to be a useful tool in the diagnosis of pancreatic cancer. Telomerase is made up of three major parts namely, human telomerase reverse transcriptase, human telomerase and telomerase -associated protein. Several researchers have shown telomerase activity in tissues and fluids of patients with pancreatic and other types of cancers. About 95 per cent telomerase activity has been detected in pancreatic adenocarcinoma. Since telomerase activity is present in a vast majority of human cancers, it might have a role in the diagnosis and treatment of cancer.

The distribution of telomerase activity in patients with Helicobacter pylori positive gastritis

Helicobacter pylori is considered a class I carcinogen by the World Health Organization. We aimed to determine whether H. pylori has an effect on telomerase activity in patients with H. pylori related non-specific gastritis, atrophy, and intestinal metaplasia. Materials and methods: One hundred and seventy-two adult patients who underwent upper gastroduodenoscopy were enrolled in the study. Three biopsy specimens were taken from the antrum: 1 from the incisura angularis and 2 from the mid-antrum. Biopsy specimens taken from the incisura angularis were evaluated using the urease test for detection of H. pylori. The mid-antrum specimens were sent for histopathology and tissue telomerase activity testing. The histopathologic evaluation was performed based on the updated Sydney system. Quantitative detection of hTERT mRNA was performed with the available method for telomerase activity. Results: Of the 172 patients, 119 were eligible for the study. H. pylori was positive in 68 (57.14%) and negative in 51 (42.85%) of the cases (P > 0.05). Of the 119 patients, 6 had intestinal metaplasia, 27 had glandular atrophy, 62 had neutrophilic activation, and 102 had chronic inflammation. The telomerase activity of the H. pylori positive and negative groups did not show a statistically significant difference in patients with intestinal metaplasia, glandular atrophy, neutrophilic activation, and chronic inflammation (P > 0.05, for each). hTERT activity was higher in H. pylori positive patients who had glandular atrophy and intestinal metaplasia than the negative group. However, the differences were insignificant. Conclusion: We could not find any significant relationship between telomerase activity and H. pylori related non-specific gastritis, atrophy, and intestinal metaplasia. hTERT activity was higher in patients who had glandular atrophy and intestinal metaplasia (early stages of gastric carcinogenesis) in the H. pylori positive group. However, these differences were not significant. H. pylori, which is considered an oncogenic agent, may influence telomerase activity of further stages of carcinogenesis, particularly those after intestinal metaplasia.

Telomerase activity is not related to life history stage in the jellyfish Cassiopea sp.

The polyp (scyphistoma) of the jellyfish Cassiopea sp. can be maintained in culture for a long time, as polyps repeatedly reproduce asexually via formation of vegetative buds or propagules. The medusa, which is the sexually reproducing stage, typically has a relatively short life span. As a first step to understand the difference in life spans of the polyp and medusa stages of Cassiopea sp., we measured telomerase activity in different life cycle stages. We found telomerase activity in tissues of aposymbiotic polyps and propagules and symbiotic ephyrae (newly budded medusae) and adult medusae. No significant difference in telomerase activity was found between polyps and the bell region of the medusae. The cloned elongation products of the stretch PCR contained the TTAGGG repeats suggesting that the jellyfish has the ‘vertebrate’ telomere motif (TTAGGG) n . This is the first study to show that somatic tissues of both polyp and medusa stages of a cnidarian had telomerase activity. Telomerase activity in somatic tissues may be related to the presence of multipotent interstitial cells and high regenerative capacity of cnidarians.

Effects of Telomerase Activity on Carcinogenesis and Survival in Laryngeal Carcinoma

This study aimed to look at whether a correlation exists between telomerase activity and survival of laryngeal carcinoma patients. Telomerase activity was measured by telomerase repeat amplification protocol in 31 laryngeal carcinomas and adjacent normal tissues, and in 21 vocal cord polyps (controls). Follow-up was for at least 60 months. Telomerase activity in tissues adjacent to laryngeal carcinomas was significantly higher than in the carcinomas which was, in turn, significantly higher than in vocal cord polyps. There was no significant difference between telomerase activity in carcinomas or adjacent tissues and clinicopathological characteristics. Patients with high telomerase activity in carcinoma tissue had significantly shorter survival times than those with low activity, but no significance difference was observed between survival time and telomerase status in adjacent tissues. Linear regression showed significant association between telomerase activity levels in carcinoma tissues and survival time, but this was not observed in adjacent tissues. This study suggests that telomerase activation probably takes place before the cancer phenotype develops and has prognostic significance for survival of patients with laryngeal carcinoma.

Determination of qualitative telomerase activity as an adjunct to the diagnosis of pancreatic adenocarcinoma by EUS-guided fine-needle aspiration

Telomerase activity is up-regulated in pancreatic cancer. Hence, measurement of telomerase activity in pancreatic needle-biopsy specimens could assist in establishing a positive diagnosis in specimens that are inadequate for cytology. To determine the sensitivity and specificity of telomerase activity for neoplasia in a series of EUS-guided fine-needle aspirate (EUS-FNA) biopsies of pancreatic mass lesions. Prospective, consecutive, non-randomized cohort. Academic hospital, tertiary referral center. Seventy-one patients with a pancreatic mass diagnosed by cross-sectional imaging. EUS-FNA of 52 solid and 18 cystic pancreatic lesions. (1) Cytologic diagnosis; (2) tissue telomerase activity by semi-quantitative polymerase chain reaction; (3) patient demographics; (4) clinical outcomes. Cytology results were positive for adenocarcinoma in 40 patients with a solid pancreatic mass; of these, telomerase activity was detected in 31. There were no telomerase false-positive results. Telomerase results were positive in 6 of the 7 patients (86%) who had negative cytology results and who eventually were found to have biopsy-proven adenocarcinoma. The sensitivity and specificity of telomerase activity for detecting pancreatic adenocarcinoma in solid masses was 79% (95% CI, 64%-89%) and 100% (95% CI, 55%-100%). Extremely high sensitivity and specificity of EUS-FNA cytology in solid lesions minimized the incremental benefit of telomerase. Telomerase activity can be measured readily in specimens obtained at EUS-FNA and accurately predicts malignancy. Used in combination with cytology, telomerase increased the sensitivity from 85% to 98% while maintaining the specificity at 100%. Lesions with negative cytology result and positive telomerase activity should be evaluated aggressively to exclude malignancy.

Improved TRAP-silver staining versus conventional radioactive TRAP assays: quantification of telomerase activity during immortalization and in pathological human endometrium

Objectives : To develop a sensitive telomeric repeat amplification protocol (TRAP)-silver staining assay for telomerase activity quantification. Design and methods : TRAP assays were performed by using a TRAPeze R telomerase kit with or without [α- 32P]-dCTP. Amplification products were electrophoresed in polyacrylamide gels and detected by autoradiography or a modified silver staining protocol. Telomerase activity was quantified from radioactive counts or optical density of telomerase products from test extracts and controls. Results : TRAP-silver staining assay was at least as sensitive as radioactive TRAP assay and quantified telomerase activity within linearity from 10 to 3,000 cell equivalents. Both methods quantified a weak telomerase activity in normal endometrial glandular epithelial cells (GEC) and a strong increase in immortalized GEC. In human pathologic endometria ( n = 24), telomerase activity was correlated with lesion seriousness and distinguished simple hyperplasias from nonhyperplasic or cancerous lesions. Conclusions : TRAP-silver staining assay is suitable for cell and tissue telomerase activity routine quantification.

Clinical significance of telomerase activity and peripheral venous blood CK-20 expression in bladder transitional cell carcinoma

Objective: The relationship between peripheral blood CK-20 mRNA expression and tissue telomerase activity in bladder transitional cell carcinoma (TCCB) was investigated to evaluate the feasibility of their combined detection in early-stage diagnosis and prognosis estimation of TCCB. Methods: the blood CK-20 was detected by semi-nested RT-PCR and telomerase activity in tumor tissue was examined with silver-stained TRAP reaction. Results: the blood CK-20 expression and tissue telomerase activity in TCCB were 41% and 93% respectively. No statistical significance was detected among pathological grading and clinical staging (P&s>0.05). Positive correlation was shown between CK-20 expression and telomerase activity with the pathologic grade or clinical stage. Conclusion: combined use of blood CK-20 and tissue telomerase activity detections might be of great importance for clinical diagnosis, treatment and prognosis evaluation.

Mechanism regulating telomerase activity in Oryza sativa L.

A stretch PCR-based method used to measure human telomerase activity was modified for use with plant telomerase and shown to be useful for quantitative analysis. We isolated a full-length cDNA of a telomerase reverse transcriptase catalytic subunit gene from suspension-cultured cells of rice ( Oryza sativa L.). A single copy of this gene is present in the rice genome. Telomerase activity was detected in suspension-cultured O. sativa cells at all growth stages, although the activity was greatest in 2-day-old subcultures and decreased at 6 days. Nevertheless, the accumulation of O. sativa telomerase mRNA was nearly constant in cells at all growth stages. Although no telomerase activity was detected in the lower portions of blades in 3-month-old rice plants, telomerase mRNA accumulated in the blades. Tests of different tissues excised from rice seedlings 3 weeks after sowing showed that root tips had high telomerase activity, while roots without root tips had no telomerase activity. Nevertheless, telomerase mRNA accumulated in both tissues. These results suggest that telomerase activity in tissues of O. sativa is regulated at the post-transcriptional or post-translational levels.

In situ detection of TGF betas, TGF beta receptor II mRNA and telomerase activity in rat cholangiocarcinogenesis.

Initial report on the in situ examination of the mRNA expression of transforming growth factor betas (TGFbetas), TGFbeta type II receptor (TbetaRII) and telomerase activity in the experimental rat liver tissue during cholangiocarcinogenesis. Rat liver cholangiocarcinogenesis was induced by 3'-methyl 4-dimethylazobenzene (3'Me-DAB). In situ hybridization was used to examine the TGFbetas) and TGFbeta type II receptor (TbetaRII) mRNA, in situ TRAP was used to check the telomerase activity in the tissue samples. There was no TGFbetas, TbetaRII mRNA expression or telomerase activity in the control rat cholangiocytes. The expression of TGFbeta1, TbetaRII was increased in regenerative, hyperplastic, dysplastic cholangiocytes and cholangiocarcinoma (CC) cells. The expression of TGFbeta2 mRNA was observed in only a part of hyperplastic, dysplastic cholangiocytes. TGFbeta3 expression was very weak, only in hyperplastic lesion. There was positive telomerase activity in the regenerative, hyperplastic, dysplastic cholangiocytes, and CC cells. Stroma fibroblasts of these lesions also showed positive TGFbetas, TbetaRII mRNA expression and telomerase activity. There were TGFbetas, TbetaRII expression and telomerase activity in hyperplastic, dysplastic cholangiocytes, cholangiocarcinoma cells as well as in stroma fibroblasts during cholangiocarcinogenesis. Their expression or activity is important in cholangiocarcinogenesis andstroma formation.

Evaluation of PCR-ELISA for determination of telomerase activity in prostate needle biopsy and prostatic fluid specimens

The conventional TRAP assay will determine telomerase activity in tissue or other specimens. However, methodological disadvantages limit its clinical use. We evaluated a modified TRAP assay, the telomerase PCR-ELISA, as a practical clinical system for measuring its activity in conjunction with prostate cancer (PCa). We examined telomerase activity by both TRAP and PCR-ELISA assays in 48 sextant needle biopsy (SNB) specimens from dye-marked areas of the prostate glands of 7 PCa patients. Each specimen was histologically confirmed as cancerous or cancer-free by examining a paired specimen taken from the same marked area. In addition, prostatic fluid (PF) specimens were analyzed from 18 patients, 9 of whom were diagnosed with PCa while 9 were diagnosed as cancer-free but mostly with BPH. The results on individual SNB specimens matched well for the two methods. The sensitivity (91%) and specificity (69%) for the PCR-ELISA measurements were consistent with those for the conventional TRAP assay, 88% and 81%, respectively. Quantitatively, with the PCR-ELISA assay, the mean telomerase activity (24.5±28.4 units) per needle core with PCa cells was significantly higher than that in needle cores without PCa cells (7.2±2.2 unit), as it was with the conventional TRAP assay, namely 25.6±27.8 units and 7.3±1.8 units, respectively. In PF specimens from PCa patients, which had a lower mean telomerase than was found in needle cores containing PCa cells (7.1±1.5 units in the PCR-ELISA, 7.2±1.8 units in the conventional TRAP assay), statistical analysis showed good matching between the results from the two assays, overall. In conclusion, the PCR-ELISA can be considered a reliable method to determine telomerase activity as an adjunct in the diagnosis and treatment of prostate cancer .

New attempt of preoperative differential diagnosis of thyroid neoplasms by telomerase activity measurement

Telomerase activity (TA) has been shown highly expressed in various solid malignant neoplasms, but only rarely in benign tumor or normal tissues. Most reports examined TA by the qualitative method, telomeric repeat amplification protocol (TRAP) assay. We examined TA in tissues of thyroid neoplasm by quantitative method to establish whether TA was a useful marker for preoperative differential diagnosis of thyroid tumors. TA was measured by the quantitative method, TRAP assay, fluorescence based TRAP method in 32 frozen tissues of thyroid tumors (17 malignant, 15 benign). Cut-off values in TA were 0 unit and 9 units from mean +/- 2SD of TA in benign thyroid tumors. Mean (SD) TA levels in benign thyroid tumors and thyroid carcinomas were 2.06 (3.58) units and 30.5 (38.2), respectively. Mean TA of carcinomas was significantly higher than that of benign disease in thyroid tumors (p=0.0092). The sensitivity of the malignancy was 64.7% (cut-off <0) (p=0.162), 52.9% (cut-off <9) (p=0.0048). TA in thyroid carcinoma was significantly correlated with UICC stage (p=0.029), and slightly correlated with tumor size, pN and M. Positive rate of TA in microfollicular adenoma was slightly higher than that in macrofollicular adenoma. Conclusively, quantitative TA might be a useful marker for differential diagnosis between benign and malignant thyroid tumors.

Specific Identification of Telomerase Activity and p53 Gene Product in Metachronous Multiple Oral Squamous Cell Carcinoma and Adjacent Tissues

Objectives: To define the association of telomerase activity, histopathological characteristics, and p53 gene product expression in metachronous oral squamous cell carcinomas.Patients and Methods: Three regions of tissue specimens from the tumour, the region adjacent to the tumour, and intact oral mucosa from the surgical margin from 2 patients were simultaneously evaluated. Telomerase activity was determined by telomeric repeat amplification protocol assay. Hematoxylin and eosin stain and DO7 monoclonal antibody were used to stain formalin-fixed, paraffin-embedded sections to examine the histopathological features and p53 gene product expression.Results: Marked telomerase activity was expressed in tumour tissue and in adjacent dyskeratotic tissue. No telomerase activity was found in hyperkeratotic or dysplastic oral mucosa. Although p53 gene product was detected in the tumour and adjacent regions of both patients, it was found in the intact oral mucosa of only 1 patient.Conclusion: Estimation of tissue telomerase activity and p53 gene product expression is helpful in identifying malignancy in oral mucosal lesions.

Telomerase activity in gestational trophoblastic disease and placental tissue from early and late human pregnancies.

The aim of this study was to evaluate telomerase activity in tissue from cases of gestational trophoblastic disease (GTD) and in placental tissue from early and late human pregnancies. We used a telomeric repeat amplification protocol assay to measure telomerase activity in 132 tissue samples from normal early pregnancies, spontaneous abortions, normal late pregnancies, cases of late-pregnancy intrauterine fetal death, and GTD. Telomerase activity was detected more often in normal early pregnancies and cases of GTD than in spontaneous abortions and normal late pregnancies (P < 0.001). During early gestation, no significant difference in detection rates was found between normal pregnancies and complete hydatidiform mole. As gestational age increased, detection rates for normal pregnancies decreased significantly (P = 0.0001), while for complete hydatidiform mole no significant changes occurred. Our findings indicate that placental tissue from normal early pregnancies and neoplastic tissue from GTD possess similar levels of telomerase activity. Decreasing regulation of telomerase activity is present in normal pregnancies but not in complete hydatidiform mole. The fact that telomerase activity decreases in cases of fetal demise, and as pregnancy progresses, also suggests that placental senescence may play a role in the development and ageing of the placenta.

Telomerase is not activated in human hyperplastic and adenomatous parathyroid tissue.

Telomerase is a specific enzyme that appears to have a key role in cellular senescence and the progression of neoplastic tissue. High telomerase activity has been found in several cancers, but not in most normal and benign tissue. Little is known about the influence of telomerase on the abnormal growth associated with hyperparathyroidism. To analyse telomerase activity in parathyroid tissue obtained from 29 patients undergoing surgery for primary hyperparathyroidism. Tissue for telomerase activity measurements was collected from six hyperplastic, 20 adenomatous and 22 normal parathyroid glands. The highly sensitive PCR-based telomeric repeat amplification protocol, TRAP, combined with ELISA, was used to detect telomerase activity in tissue extracts containing 3.0 microg protein. Telomerase was not activated in any of the analysed tissue by 3 microg protein. Reassay of 12 samples containing 6.0 microg protein verified these negative TRAP results. Our findings indicate that telomerase is not a part of the mechanism promoting parathyroid proliferation and the underlying conditions remain to be determined.

Development of a quantitative luminometric hybridization assay for the determination of telomerase activity

Objectives: To develop a quantitative luminometric hybridization assay for the determination of telomerase activity in tissue and cell extracts. Design and Methods: Quantification is based on the coamplification of telomeric repeats synthesized by telomerase along with a specifically designed recombinant DNA-internal standard (DNA-IS). The DNA-IS has a similar size and the same primer recognition sites as the telomerase DNA products and differs from them only in a central 18 bp sequence. PCR products are captured on microtiter wells via the biotin-streptavidin system and hybridized with two distinct digoxigenin-labeled oligonucleotide probes that are designed to recognize specifically telomerase products and DNA-IS. The hybrids are quantified by a luminometric reaction using an antidigoxigenin antibody conjugated to alkaline phosphatase. The hybridization assay was validated with the MCF-7 breast carcinoma and leukemia K-562 cell lines and a synthetic telomerase product (R 8). Results: Luminescence ratios for telomerase products and DNA-IS were linearly related to the concentration of the pre-PCR product synthesized by telomerase (R 8), in the range of 0.0005 to 10 pM. The overall reproducibility of the assay (between-run) varied between 11.3 and 15%. Application of the method in eleven breast tumors showed a great variation in the levels of telomerase enzymatic activity. Conclusions: The proposed luminometric hybridization assay for the quantitative determination of telomerase enzymatic activity is highly sensitive and can be used for a large-scale prospective evaluation of clinical samples.

Telomerase activity in gastric cancer

OBJECTIVE: To examine telomerase activity and its clinical significance in human gastric carcinoma and to evaluate the feasibility of non-radioisotopic TRAP (telomeric repeat amplification protocol) assays to detect telomerase activity. METHODS: Telomerase activity in tissue samples from 58 gastric carcinomas (and their matched normal tissues), 12 gastric adenomas and nine gastric ulcers was examined by using a modified non- radioisotopic PCR (polymerase chain reaction)-based TRAP assay. RESULTS: Forty-nine of 58 gastric cancer specimens were positive for telomerase activity, with a positive rate of 84.5%. In contrast, none of the normal tissues exhibited telomerase activity (P < 0.001). One of each of the 12 gastric adenomas and nine gastric ulcers was also positive. The prevalence of telomerase activity in gastric carcinoma tissues was not correlated with age, tumor diameter, histological grade, tumor invasion depth, lymph node metastasis or tumor node metastasis (TNM) stage. CONCLUSIONS: Telomerase activity could be a good diagnostic marker for the detection of gastric carcinoma. The non-radioisotopic TRAP assay is a feasible method for detecting telomerase activity.

Telomerase activity in peripheral blood for diagnosis of hepatoma.

Telomerase activity may be used as a molecular marker for the detection of circulating hepatoma cells in blood of patients with hepatoma. Telomerase activity in peripheral blood from hepatocellular carcinoma (HCC) patients was assessed by using a highly sensitive and non-radioisotope telomerase polymerase chain reaction (PCR) ELISA. Initially, tissue telomerase activity was measured in the hepatoma and non-tumour portions by using PCR ELISA within the same specimen, to compare its sensitivity with the conventional telomeric repeat amplification protocol (TRAP) method. Second, telomerase activity was measured in the peripheral blood obtained from patients with HCC, patients with chronic liver disease and in healthy controls. Of the 17 HCC patients, telomerase activity was found to be positive in 14 (82%) by using TRAP and 15 (88%) by using PCR ELISA, indicating that PCR ELISA is a reliable tool for the measurement of telomerase activity. By using the Telomerase PCR ELISA assay, telomerase activities in the peripheral blood of 20 HCC patients was 1.65 +/- 0.78 units. This was significantly greater than the results obtained for 20 chronic liver disease patients (0.43 +/- 0.36 units) and 20 healthy controls (0.39 +/- 0.14 units; P < 0.0001).When the arbitrary cut-off level was set at 0.7 units (maximum value of healthy controls + 0.1), the positive frequency of telomerase activity was 25% for chronic liver disease and 80% for HCC patients (sensitivity 80%, specificity 75%). Among the HCC patients, high telomerase activity in the peripheral blood was shown at stage III HCC with vascular invasion (2.10 +/- 0.62 units, n = 9). This was significantly higher than patients at stage II of HCC (1.28 +/- 0.72 units, n = 11, without vascular invasion; P = 0.012). These results suggest that peripheral blood telomerase activity, which may reflect haematogenous micrometastasis, is potentially a practical diagnostic/predictive marker of HCC.