Telomerase activity as a potential marker in preneoplastic bladder lesions

Recent advances in esophageal squamous cell precancerous conditions: A review

Esophageal squamous cell carcinoma (ESCC) is a common cancer in many developing countries in Asia and Africa, with a 5-year survival rate of approximately 20%. Most cases are diagnosed at an advanced age when there is no effective treatment strategy. Esophageal precancerous conditions have a much better prognosis, with a 5-year survival rate of over 90% by endoscopic diagnosis and treatment. Nevertheless, limitations, contraindications, and lymph node metastasis incompetency of endoscopy. Thus, the diagnosis and treatment of esophageal precancerous lesions remain a significant challenge. Biomarker investigations provide opportunities for target detection and therapy. Additionally, drug development is ongoing. Changes in lifestyle habits, such as diet balance, smoking and alcohol cessation, are beneficial for the prognosis of esophageal precancerous lesions. Collectively, multiple and sequential diagnoses and treatments are essential for curing esophageal precancerous lesions and reducing the incidence and mortality of ESCC.

Detecting and monitoring bladder cancer with exfoliated cells in urine

Current methods for the diagnosis and monitoring of bladder cancer are invasive and have suboptimal sensitivity. Liquid biopsy as a non-invasive approach has been capturing attentions recently. To explore the ability of urine-based liquid biopsy in detecting and monitoring genitourinary tumors, we developed a method based on promoter-targeted DNA methylation of urine sediment DNA. We used samples from a primary bladder cancer cohort (n=40) and a healthy cohort (n=40) to train a model and obtained an integrated area under the curve (AUC) > 0.96 in the 10-fold cross-validation, which demonstrated the ability of our method for detecting bladder cancer from the healthy. We next validated the model with samples from a recurrent cohort (n=21) and a non-recurrent cohort (n=19) and obtained an AUC > 0.91, which demonstrated the ability of our model in monitoring the progress of bladder cancer. Moreover, 80% (4/5) of samples from patients with benign urothelial diseases had been considered to be healthy sample rather than cancer sample, preliminarily demonstrating the potential of distinguishing benign urothelial diseases from cancer. Further analysis basing on multiple-time point sampling revealed that the cancer signal in 80% (4/5) patients had decreased as expected when they achieved the recurrent-free state. All the results suggested that our method is a promising approach for noninvasive detection and prognostic monitoring of bladder cancer.

Eosinophilic cystitis complicated with cystitis glandularis: a case report

Background

Eosinophilic cystitis (EC) is a rare inflammatory disease characterized by the gathering and infiltration of numerous eosinophilia (EOS) in the bladder wall. Because of Few cases of EC have been reported globally, the epidemiology of EC is not well known. We report herein the details of one very scarce case of large tumor-like eosinophilic cystitis complicated with cystitis glandularis (CG) diagnosed by biopsy.

Case presentation

A 45-year-old Chinese man was referred to our hospital for the treatment of right lumbago and odynuria. Ultrasound examination indicated the low echo on the right portion wall and the neck of the bladder. Computed tomography showed a remarkable enhancing large mass that measured 5.0 cm × 2.3 cm located on the right portion of the bladder with undefined margin. For further treatment, diagnostic transurethral resection of the bladder was performed, the postoperative histopathological diagnosis was EC complicated with CG. After transurethral resection, antibiotics, glucocorticoids, and antihistamines were treated. The patient recovered uneventfully and was discharged on postoperative day 8 without evidence of recurrence followed-up for 6 months.

Conclusion

Large tumor-like eosinophilic cystitis complicated with cystitis glandularis is rare, malignant tumors need to be ruled out. We deem that prompt biopsy led to the exact diagnosis, appropriate treatment led to better prognosis.

The methylation status and expression of human telomerase reverse transcriptase is significantly high in oral carcinogenesis

Telomerase activity is present in most cancers and is tightly regulated by the expression of human telomerase reverse transcriptase (hTERT). Hypermethylation in the promoter region of hTERT contributes to the regulation of hTERT expression. In this study, we investigated the methylation and expression of hTERT in oral squamous cell carcinoma (OSCC), oral leukoplakia, and normal oral mucosa. Furthermore, we investigated the significance of hTERT to the clinicopathological findings of OSCC. 35 OSCC, 50 oral leukoplakia (epithelial dysplasia n = 25, squamous cell hyperplasia n = 25), and 10 normal oral mucosa samples were investigated through methylation-specific PCR. Immunohistochemistry was analyzed in 35 OSCC, 50 oral leukoplakia, and 4 normal oral mucosa samples. The methylation and expression of hTERT increased from normal oral mucosa to oral leukoplakia to OSCC. In OSCC, all samples were methylated. However, partial methylation (20%) or unmethylation (80%), but never complete methylation, was observed in normal oral mucosa. Additionally, hTERT expression correlated with cervical lymph node metastasis. These results suggested that the methylation and expression of hTERT is high in oral carcinogenesis and may play an important role in oral cancer. hTERT expression may also be predictive of cervical lymph node metastasis.

Telomerase activity and its association with psychological stress, mental disorders, lifestyle factors and interventions: A systematic review

OBJECTIVE

To summarise and discuss the association between telomerase activity and psychological stress, mental disorders and lifestyle factors.

METHOD

A systematic review was carried out to identify prospective or retrospective studies and interventions published up to June 2015 that reported associations between telomerase activity and psychological stress, mental disorders and lifestyle factors. Electronic data bases of PubMed, ProQuest, CINAHL and Google Scholar were searched.

RESULTS

Twenty six studies on humans measured telomerase activity in peripheral blood mononuclear cells (PBMCs) or leukocytes and examined its association with psychological stress, mental disorders and lifestyle factors. Of those studies, three reported significantly decreased telomerase activity in individuals under chronic psychological stress. Interestingly, one of the three studies found that acute laboratory psychological stress significantly increased telomerase activity. Nine studies reported mixed results on association between mental disorders and telomerase activity. Of the nine studies, five reported that major depressive disorder (MDD) was associated with significantly increased telomerase activity. In thirteen out of fourteen studies on lifestyle factors, it was reported that physical exercise, diet micronutrient supplementation, mindfulness meditation, Qigong practice or yoga mediation resulted in increase in telomerase activity. In addition, two studies on animal models showed that depression-like behaviour was associated with decreased hippocampus telomerase activity. Five animal studies showed that physical exercise increased telomerase activity by cell-type-specific and genotype-specific manners.

CONCLUSION

Although multi-facet results were reported on the association between telomerase activity and psychological stress, mental disorders and lifestyle factors, there were some consistent findings in humans such as (1) decreased telomerase activity in individuals under chronic stress, (2) increased telomerase activity in individuals with MDD, and (3) increased telomerase activity in individuals under lifestyle interventions. Animal studies showed that physical exercise increased telomerase activity in specific cell-types. However, the exact mechanisms for the changes in telomerase activity have not been elucidated. We propose conglomerate models connecting chronic psychological stress, depression, mediation and physical exercise to telomerase activation. Several areas for future research are suggested.

A pilot study on intravesical administration of curcumin for cystitis glandularis

Cystitis glandularis (CG) is a proliferative disorder in the urinary bladder. The outcome of current treatments in some patients is not satisfactory. Curcumin, a herbal medicine that has been used for centuries, has shown great potential in treating various diseases. Our pilot study aimed to explore the feasibility of an intravesical treatment for CG using curcumin. 14 patients diagnosed with CG that remained symptomatic after primary treatments were enrolled, underwent a 3-month curcumin intravesical treatment (50 mg/50 mL, 1 hour, once per week for first 4 weeks and once per month for next 2 months) and were followed up for 3 months. Efficacy of the treatment was evaluated using core lower urinary tract symptom score (CLSS) questionnaire. 10 patients demonstrated persistent improvement in symptoms up to the end of the 6-month study. Their CLSS decreased significantly after the 3-month treatment (6.0 ± 0.8; P < 0.01) from the baseline (10.5 ± 1.6) and maintained decreasing till the end of the study (6.2 ± 0.7; P < 0.01). 4 patients were classified as nonresponders. Our study suggests the feasibility of further randomized controlled trials on curcumin intravesical treatment in CG patients who remain symptomatic after primary treatments.

Prevalence of telomerase activity in human cancer

Telomerase activity has been measured in a wide variety of cancerous and non-cancerous tissue types, and the vast majority of clinical studies have shown a direct correlation between it and the presence of cancerous cells. Telomerase plays a key role in cellular immortality and tumorigenesis. Telomerase is activated in 80-90% of human carcinomas, but not in normal somatic cells, therefore, its detection holds promise as a diagnostic marker for cancer. Measurable levels of telomerase have been detected in malignant cells from various samples: tissue from gestational trophoblastic neoplasms; squamous carcinoma cells from oral rinses; lung carcinoma cells from bronchial washings; colorectal carcinoma cells from colonic luminal washings; bladder carcinoma cells from urine or bladder washings; and breast carcinoma or thyroid cancer cells from fine needle aspirations. Such clinical tests for telomerase can be useful as non-invasive and cost-effective methods for early detection and monitoring of cancer. In addition, telomerase activity has been shown to correlate with poor clinical outcome in late-stage diseases such as non-small cell lung cancer, colorectal cancer, and soft tissue sarcomas. In such cases, testing for telomerase activity can be used to identify patients with a poor prognosis and to select those who might benefit from adjuvant treatment. Our review of the latest medical advances in this field reveals that telomerase holds great promise as a biomarker for early cancer detection and monitoring, and has considerable potential as the basis for developing new anticancer therapies.

Telomerase detection in the diagnosis and prognosis of cancer

Telomerase, a critical enzyme responsible 'for cellular immortality, is usually repressed in somatic cells except for lymphocytes and self-renewal cells, but is activated in approximately 85% of human cancer tissues. The human telomerase reverse transcriptase (hTERT) is the catalytic component of human telomerase. In cancers in which telomerase activation occurs at the early stages of the disease, telomerase activity and hTERT expression are useful markers for the detection of cancer cells. In other cancers in which telomerase becomes upregulated upon tumor progression, they are useful as prognostic indicators. However, careful attention should be paid to false-negative results caused by the instability of telomerase and of the hTERT mRNA and the presence of PCR inhibitors, as well as to false-positive results caused by the presence of alternatively spliced hTERT mRNA and normal cells with telomerase activity. Recently, methods for the in situ detection of the hTERT mRNA and protein have been developed. These methods should facilitate the unequivocal detection of cancer cells, even in tissues containing a background of normal telomerase-positive cells.

Expression of hTERT, p53 and PCNA in cystitis glandularis

To examine the expression of human telomere reverse transcriptase (hTERT), p53 and proliferating cell nuclear antigen (PCNA) in cystitis glandularis, 38 patients were divided into two groups: group A (including 18 cases of papillary cystitis glandularis) and group B (including 20 subjects with normal bladder mucosa). All the cases were immunohistochemically examined by using antibodies specifically against p53 and PCNA, and hTERT was determined by in situ hybridization. hTERT was found in 6 cases (33.3%) and p53 was detected in 4 cases (22.2%) in group A, while they were not detected in group B. There were significant differences in hTERT and p53 expression between groups A and B (P<0.05 for both). PCNA was detected in 7 cases (38.9%) in group A and 1 case (5.0%) in group B, and significant difference in PCNA expression was found between the two groups (P<0.05). The expressions of hTERT, p53 and PCNA were significantly higher in group A than in group B, suggesting that papillary cystitis glandularis is predisposed to cancerous change, and p53, PCNA, hTERT may be related to the malignant alteration.

Effects of combined siRNA-TR and -TERT on telomerase activity and growth of bladder transitional cell cancer BIU-87 cells

The effects of combined RNA interference (RNAi) of human telomerase RNA (hTR) and human telomerase reverse transcriptase (hTERT) genes on telomerase activity in a bladder cancer cell line (BIU-87 cells) were investigated by using gene chip technology in vitro with an attempt to evaluate the role of RNAi in the gene therapy of bladder transitional cell cancer (BTCC). Three TR-specific double-stranded small interfering RNAs (siRNAs) and three TERT-specific double-stranded siRNAs were designed to target different regions of TR and TERT mRNA. The phTR-siRNA, phTERT-siRNA, and the combination of both plasmids phTR+phTERT-siRNA were transfected into BIU-87 cells. The expression of hTR and hTERT mRNA was detected by quantitative fluorescent reverse transcription-polymerase chain reaction, and a telomeric repeat amplification protocol was applied to detect telomerase activity. Growth inhibition of BIU-87 cells was measured by MTT assay. Gene chip analysis was performed to evaluate the effects of the combined RNAi of hTR+hTERT genes on telomerase activity and growth of BIU-87 cells in vitro. The results showed that the expression of hTERT and hTR mRNA was inhibited by pRNAT-hTERT-III, pRNAT-hTR-III, and pRNAT-hTR-III+hTERT-III in BIU-87 cells. The inhibition efficiency of pRNAT-hTERT-III, pRNAT-hTR-III, pRNAT-hTERT-III+pRNAT-hTR-III was 67% for TERT mRNA, 41% for TR mRNA, 57% for TR mRNA and 70% for TERT mRNA in BIU-87 cells respectively. The growth of BIU-87 cells was inhibited and telomerase activity was considerably decreased, especially in the cells treated with combined RNAi-hTR and -hTERT. Gene chip analysis revealed that 21 genes were down-regulated (ATM, BAX, BCL2, BCL2L1, BIRC5, CD44, CTNNB1, E2F1, JUN, MCAM, MTA1, MYC, NFKB1, NFKBIA, NME4, PNN, PNN, SERPINE1, THBS1, TNFRSF1A, and UCC1). The results indicated that hTR-siRNA and hTERT-siRNA, especially their combination, siRNA hTR+hTERT, specifically and effectively suppressed the expression of both hTR and hTERT mRNA and telomerase activity. Molecular biological mechanism by which combined siRNA-TR and -TERT inhibited telomerase activity and growth of BIU-87 cells in vitro may involve the down-regulation of the 21 genes.

Telomere-centromere-driven genomic instability contributes to karyotype evolution in a mouse model of melanoma

Aneuploidy and chromosomal instability (CIN) are hallmarks of most solid tumors. These alterations may result from inaccurate chromosomal segregation during mitosis, which can occur through several mechanisms including defective telomere metabolism, centrosome amplification, dysfunctional centromeres, and/or defective spindle checkpoint control. In this work, we used an in vitro murine melanoma model that uses a cellular adhesion blockade as a transforming factor to characterize telomeric and centromeric alterations that accompany melanocyte transformation. To study the timing of the occurrence of telomere shortening in this transformation model, we analyzed the profile of telomere length by quantitative fluorescent in situ hybridization and found that telomere length significantly decreased as additional rounds of cell adhesion blockages were performed. Together with it, an increase in telomere-free ends and complex karyotypic aberrations were also found, which include Robertsonian fusions in 100% of metaphases of the metastatic melanoma cells. These findings are in agreement with the idea that telomere length abnormalities seem to be one of the earliest genetic alterations acquired in the multistep process of malignant transformation and that telomere abnormalities result in telomere aggregation, breakage-bridge-fusion cycles, and CIN. Another remarkable feature of this model is the abundance of centromeric instability manifested as centromere fragments and centromeric fusions. Taken together, our results illustrate for this melanoma model CIN with a structural signature of centromere breakage and telomeric loss.

Telomerase activity in bladder cancer tissue

Telomerase is a ribonucleoprotein enzyme that maintains telomeric DNA repeats at the end of chromosomes. Telomerase activity has been reported in many human cancers. The present study evaluated telomerase activity in bladder cancer tissue and investigated whether this activity is associated with tumor characteristics and prognosis in bladder cancer patients. Telomerase activity was investigated using the telomeric repeat amplification protocol (TRAP) in bladder tissue specimens from 81 patients, including 75 patients with bladder carcinoma and 6 patients with dysplasia or an inflammatory bladder lesion. Forty-nine of the 75 bladder cancer patients were found to be telomerase-positive, while 1 out of the 6 control specimens without carcinoma was telomerase-positive. Telomerase activity was correlated with lower grade and lower stage bladder cancer, but was not significantly associated with cancer-specific survival in the total population of bladder cancer patients. However, telomerase-positive patients among the patients with invasive and grade 3 tumors had an improved prognosis. Telomerase activity was observed in early-stage bladder cancer, and may be an indicator of prognosis in bladder cancer patients with advanced-stage and high-grade tumors.

Integrated genomic and transcriptional analysis of the in vitro evolution of telomerase-immortalized urothelial cells (TERT-NHUC)

Much progress has been made in identifying the molecular genetic alterations that occur in bladder cancer. However, in many cases the genes targeted by these alterations are not known. Telomerase immortalized human urothelial cells (TERT-NHUC) are a useful resource for in vitro studies of genes involved in urothelial transformation. When cultured under standard conditions they remain genetically stable but when cultured under low-density conditions they exhibit genetic instability and acquire chromosomal alterations. TERT-NHUC from three donors were cultured at low plating density and examined at four time-points during a culture period of 600 days. Analyses included population doubling kinetics, array-based CGH (aCGH), chromosome counts, fluorescence in situ hybridization (FISH), mutation analysis, Affymetrix gene expression analysis, Western blotting for p16, anchorage-independent growth and tumorigenicity assays. Alterations acquired during continued culture of TERT-NHUC at low density (TERT-NHUC-L) included some observed in urothelial carcinoma (UC) cell lines and primary UC. Examination of gene expression in TERT-NHUC with distinct acquired genetic aberrations may pinpoint genes targeted by these alterations. Data from an aCGH study of UC cell lines and primary tumors were examined for changes in chromosomal regions that also showed alterations in TERT-NHUC-L. Loss of a region on 2q including BOK was identified in UC cell lines and primary tumors. DNER and FRAS1 were identified as potential candidate genes, whose expression is altered independently of the acquisition of any genetic event.

RUNX3 methylation reveals that bladder tumors are older in patients with a history of smoking

Exposure to tobacco smoke is associated with increased DNA methylation at certain genes in both lung and bladder tumors. We sought to identify interactions in bladder cancer between DNA methylation and a history of smoking, along with any possible effect of aging. We measured DNA methylation in 342 transitional cell carcinoma tumors at BCL2, PTGS2 (COX2), DAPK, CDH1 (ECAD), EDNRB, RASSF1A, RUNX3, TERT, and TIMP3. The prevalence of methylation at RUNX3, a polycomb target gene, increased as a function of age at diagnosis (P = 0.031) and a history of smoking (P = 0.015). RUNX3 methylation also preceded methylation at the other eight genes (P < 0.001). It has been proposed that DNA methylation patterns constitute a "molecular clock" and can be used to determine the "age" of normal tissues (i.e., the number of times the cells have divided). Because RUNX3 methylation increases with age, is not present in normal urothelium, and occurs early in tumorigenesis, it can be used for the first time as a molecular clock to determine the age of a bladder tumor. Doing so reveals that tumors from smokers are "older" than tumors from nonsmokers (P = 0.009) due to tumors in smokers either initiating earlier or undergoing more rapid cell divisions. Because RUNX3 methylation is acquired early on in tumorigenesis, then its detection in biopsy or urine specimens could provide a marker to screen cigarette smokers long before any symptoms of bladder cancer are present.

Telomerase activity is correlated with lower grade and lower stage bladder carcinomas

BACKGROUND

Telomerase is a ribonucleoprotein enzyme that compensates for the progressive erosion of telomeres. The increasing interest in telomerase is motivated by the demonstration that most human carcinomas are telomerase positive. The potential use of telomerase activity in bladder carcinomas using a urine sample has been reported in several studies. However, little is known about the detection of telomerase activity in bladder carcinoma tissues. Herein, we investigate telomerase activity in bladder carcinoma tissues according to grade (G) and stage.

MATERIAL AND METHODS

Telomerase activity was assayed by polymerase chain reaction enzyme-linked immunosorbent assay methods. Malignant lesions were assessed in 37 patients with bladder carcinoma and no malignant lesions were assessed in five patients with dysplasia or inflammatory bladder lesions.

RESULTS

Twenty-three out of 37 carcinoma samples were telomerase-positive and one out of five control samples without carcinoma was telomerase-positive. The positive rates according to stage and grade were 83.3% for superficial and 42.1% for invasive stages and 83.3% for G1, 66.7% for G2 and 40.0% for G3. Telomerase activity was correlated with lower grade and lower stage bladder carcinomas.

CONCLUSION

These results strongly suggest that reactivation of telomerase may differ between superficial and invasive bladder carcinomas and also between low grade and high grade bladder carcinomas.

The role of beta-catenin signaling in the malignant potential of cystitis glandularis

PURPOSE

Chronic inflammation is a risk factor for malignant transformation in the bladder. The pro-inflammatory cytokine tumor necrosis factor-alpha (TNFalpha) is a mediator of such inflammation that induces nuclear localization of the adherens junction component beta-catenin. This mechanism has a key role in the initiation and progression of the premalignant lesion Barrett's metaplasia of the esophagus. Cystitis glandularis is a metaplastic lesion of the bladder urothelium occurring in the presence of chronic inflammation and in up to 13% of asymptomatic bladders. Two subtypes are described (typical and intestinal/colonic) with uncertain malignant potential. Etiologically and histologically cystitis glandularis mimics Barrett's metaplasia. We investigated the roles of beta-catenin and TNFalpha in cystitis glandularis.

MATERIALS AND METHODS

Immunohistochemistry and immunofluorescence were used to demonstrate the expression and localization of E-cadherin, beta-catenin and TNFalpha in 9 sections of typical cystitis glandularis and 4 of intestinal/colonic cystitis glandularis. Appropriate controls were used for all experiments.

RESULTS

Immunohistochemistry demonstrated normal membranous expression of E-cadherin and beta-catenin in all cystitis glandularis sections with increased TNFalpha expression. Immunofluorescence showed nuclear localization of beta-catenin in the intestinal/colonic subtype only, which was not observed in typical cystitis glandularis.

CONCLUSIONS

The presence of nuclear beta-catenin suggests that intestinal/colonic cystitis glandularis shares the same signaling pathway with the premalignant lesion Barrett's metaplasia of the esophagus and the intestinal/colonic subtype of cystitis glandularis may have the potential to progress to malignancy. This finding has important implications for the management of this lesion.

Telomerase activity in diagnosis of bladder cancer

OBJECTIVE

Telomerase is an enzyme that can reconstitute the ends of chromosomes after cell division and thus circumvent the damage that occurs in normal adult somatic cells during successive mitotic cycles. Immortal cells have short but stable chromosomes and increased telomerase activity. Transitional cell carcinoma (TCC) has only a few useful markers of diagnostic or prognostic importance. The objectives of this study were to determine whether there was a correlation between telomerase activities and the grade or stage of TCC and whether the activity of the enzyme could serve as a biochemical marker of this tumor.

MATERIAL AND METHODS

Telomerase activity was determined by examining, using a polymerase chain reaction-based assay designed using the telomeric repeat amplification protocol (TRAP), urine cell pellets obtained from 42 bladder cancer patients, 18 patients with primary hematuria, 19 patients with benign urologic disease, 14 patients with urologic malignancies other than TCC and 20 healthy volunteers.

RESULTS

Telomerase activity was found in 24/31 patients with bladder tumors (77.4% sensitivity) and in 5/77 patients without tumors (93.5% specificity). No correlation was found between telomerase activity and the grade or stage of the tumor. Although none of the urine cell pellets obtained from the 20 healthy volunteers demonstrated telomerase activity, positive telomerase activity was found in two subjects in the benign urologic disease group and in three subjects in the other urologic malignancy group. It was demonstrated that gross hematuria was the cause of false-negative results in six of the nine patients (66.7%). but washing the pellets four times and diluting them before the TRAP assay solved this problem.

CONCLUSION

These results indicate that telomerase activity may be a promising marker for TCC but the technical aspects of the technique must be improved before it is used in routine clinical practice as a standard method. False-negative results obtained using gross hematuric urine should be carefully reevaluated and cell pellets should be washed again and diluted before analysis.

Detection of human telomerase reverse transcriptase mRNA in urine of patients with bladder cancer: evaluation of an emerging tumor marker

OBJECTIVES

To assess the value of the telomerase enzyme as a bladder cancer detection marker, we investigated the expression of the catalytic subunit of the complex (human telomerase reverse transcriptase [hTERT]) in the urine of patients with malignant or benign urinary lesions, as well as of healthy individuals, and compared the results with urine cytology.

METHODS

Spontaneously voided samples were obtained from two groups of subjects: group 1, 146 previously untreated patients with a histologic diagnosis of transitional cell carcinoma or other urothelial neoplasm; and group 2, 128 control individuals, either healthy or with a nonmalignant bladder disease. Total RNA extracts from sedimented urothelial cells were analyzed by a reverse transcriptase-polymerase chain reaction assay for the presence of a 146-bp hTERT transcript. Urine samples were also examined by standard cytology.

RESULTS

Expression of hTERT was detected in 134 (92%) of 146 patients with bladder cancer, and only 64 (44%) yielded a positive result by cytology (P <0.001). The sensitivity advantage of the former technique became particularly evident in the detection of low-grade transitional cell carcinoma (93% versus 28%, P <0.001). Accordingly, the negative predictive value of the molecular assay was markedly greater than the one calculated for cytologic screening (91% versus 60%). On the other hand, both methods were at least 96% specific, with their positive predictive indexes exceeding 94%.

CONCLUSIONS

Our findings suggest that the assessment of hTERT expression in urine sediments represents a reliable tool for the detection of primary urothelial neoplasms, equally specific, yet far more sensitive, than conventional cytology.

Telomerase as tumor marker

Telomerase, a critical enzyme responsible for continuous cell growth, is repressed in most somatic cells except proliferating progenitor cells and activated lymphocytes, and activated in approximately 85% of human cancer tissues. Telomerase activity is a useful cancer-cell detecting marker in some types of cancers in which almost all cases show telomerase activation. In other types in which telomerase becomes upregulated according to tumor progression, it is a useful prognostic indicator. Detection of human telomerase reverse transcriptase (hTERT) mRNA or protein in various clinical samples is also applicable. However, careful attention should be paid to the false negative results due to the instability of this enzyme or hTERT mRNA and the existence of polymerase chain reaction inhibitors as well as the false-positive results due to the contamination by normal cells with telomerase activity. If these pitfalls are avoided, in situ detection of hTERT mRNA or protein will facilitate the reliability of telomerase as a tumor marker.

Role of telomeres and telomerase in the pathogenesis of human cancer

Specialized nucleoprotein structures, termed telomeres, cap the ends of human chromosomes. These terminal structures, composed of repetitive arrays of guanine-rich hexameric DNA together with specific telomere-binding proteins, play essential roles in protecting the chromosome from damage and degradation. In addition, several lines of evidence implicate telomere maintenance as an important regulator of cell life span. Activation of telomerase, a dedicated reverse transcriptase that synthesizes telomeric sequences, is strongly associated with cancer, and recent observations confirm that telomeres and telomerase perform important roles in both suppressing and facilitating malignant transformation. These dual functions of telomere biology are evident in the clinical manifestations of the multisystem syndrome, dyskeratosis congenita, forms of which display defects in telomerase function. Recent advances in our understanding of telomere biology indicate that the manipulation of telomeres and telomerase will lead to clinically significant applications in the diagnosis, prevention, and treatment of neoplastic disease.

Telomerase and tumorigenesis

The unique biology of telomeres and telomerase plays important roles in many aspects of mammalian cell physiology. Over the past decade, several lines of evidence have confirmed that the maintenance of telomeres and telomerase participate actively in the pathogenesis of human cancer. Specifically, activation of telomerase is strongly associated with cancer, and recent observations confirm that telomeres and telomerase perform important roles in both suppressing and facilitating malignant transformation by regulating genomic stability and cell lifespan. In addition, recent evidence suggests that telomerase activation contributes to tumorigenesis independently of its role in maintaining telomere length. Here we review recent developments in our understanding of the relationships among telomeres, telomerase, and cancer.

Detection of telomerase status by semiquantitative and in situ assays, and by real-time reverse transcription-polymerase chain reaction (telomerase reverse transcriptase) assay in bladder carcinomas

OBJECTIVE

To investigate whether telomerase activity could be used as a diagnostic and/or prognostic marker of bladder carcinoma, by assessing telomerase activity using semiquantitative and in situ methods, and quantifying telomerase reverse transcriptase (hTERT) mRNA expression in a series of bladder carcinomas.

MATERIAL AND METHODS

Telomerase activity was detected by the telomeric repeat amplification protocol (TRAP) assay using a telomerase polymerase chain reaction (PCR) enzyme-linked immunosorbent assay (ELISA) kit on a series of 29 bladder carcinomas and on three normal bladder samples. hTERT mRNA levels were quantified using real-time quantitative reverse transcription (RT)-PCR. For the in situ detection of telomerase activity, the same telomerase PCR ELISA kit was used and applied to frozen-tissue sections only for discordant cases between telomerase activity and hTERT mRNA status.

RESULTS

Telomerase activity was positive in 15 of the 29 bladder carcinomas (52%) and negative for the three normal bladder samples. hTERT was detected and quantified in all tumour samples, with major differences in hTERT values. None of the three normal bladder samples had quantifiable hTERT mRNA, giving complete sensitivity and specificity for the method in diagnosing bladder carcinoma. Comparing the results of RT-PCR and TRAP assay showed a significant association between the enzyme activity and levels of hTERT mRNA expression, with only five discordant cases, most of them being TRAP-negative and hTERT-positive. Among these cases the in situ results of telomerase activity were concordant with hTERT mRNA levels by RT-PCR and not with TRAP assay results, as nuclear fluorescence of malignant epithelial cells. The semiquantitative evaluation of positive cell numbers showed a heterogeneity of telomerase activity within the tumour tissue. There was a significant correlation between RT-PCR and histopathological variables (grade and stage), and a significant correlation between TRAP assay results and histopathological grade.

CONCLUSION

Detecting hTERT mRNA by RT-PCR seems to be a promising method, with a much better sensitivity than the TRAP assay in diagnosing bladder carcinomas, and a better correlation with histopathological variables. False-negative cases on the TRAP assay are explained by the heterogeneity of telomerase activity within tumour cells. Thus evaluating hTERT gene expression levels could be used as a marker of malignant progression, useful in the early diagnosis and follow-up of bladder carcinomas.

N/A

N/A

Prediction of survival in stage I lung carcinoma patients by telomerase function evaluation

Telomerase activity and telomerase reverse transcriptase (hTERT) expression are elevated in human malignancies. We have investigated telomerase activity measured by the telomeric repeat amplification protocol (TRAP) assay and hTERT levels by real-time RT-PCR in stage I non-small-cell lung carcinomas. The purposes of our study included the comparison of these two techniques in the assessment of telomerase function and the evaluation of their prognostic significance. Telomerase activity and hTERT levels were determined in 90 stage I non-small-cell lung carcinoma patients, using TRAP assay and real-time RT-PCR, respectively. Variables were analyzed by the chi(2) and Fisher exact tests. Survival was analyzed by the Kaplan-Meier method. Multivariate analysis was performed with the Cox's proportional hazards model. Telomerase activity was elevated in 60 (67%) carcinomas. hTERT was elevated in 43 (48%) carcinomas. Only 21 (23%) tumors had low telomerase function by both TRAP and hTERT expression levels. Telomerase activity and hTERT were significantly correlated (p = 0.017), although 35 cases displayed discordant results. Both telomerase activity and hTERT levels were significantly associated with poor patient overall and disease-free survival (p = 0.019 and p = 0.018 for TRAP, and p = 0.011 and p = 0.012 for hTERT, respectively). Among the 21 patients with tumors displaying low telomerase function, defined by both TRAP and hTERT expression levels, only one succumbed to the disease (p = 0.0053). Our results suggest that the two techniques used in this study evaluate separate aspects of telomerase function and their combination provides powerful prognostic information in lung cancer patients.

Telomerase: its clinical relevance in the diagnosis of bladder cancer

More than 50 years ago, Papanicolaou recognized the importance of a non-invasive technique for the diagnosis and follow-up of patients with carcinoma of the urinary bladder. Cystoscopy, however, has remained the 'gold standard' since no currently available non-invasive method can compete with cystoscopy's sensitivity and specificity. The detection of the ribonucleoprotein telomerase or the telomerase subunits human telomerase RNA (hTR) and human telomerase reverse transcriptase (hTERT) in urine samples offer new diagnostic perspectives. The present article presents a review of publications in the literature and evaluates their clinical relevance. The experimental studies reported to date are very promising and show that telomerase exactly fulfils the requirements for a good diagnostic marker for carcinoma of the urinary bladder. The diagnostic application remains in an experimental stage and telomerase is still several steps away for routine use as a clinical parameter. The remaining steps leading to its routine clinical application will be discussed.

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.

Telomerase activity in bilharzial bladder cancer. Prognostic implications

Background: Bladder cancer is a common malignancy in Egypt and other developing countries in which infection with Schistosoma haematobium is prevalent. Bladder cancer caused by bilharziasis has different clinical and biological characters than that observed in the western world. In this study, we used the TRAP technique to estimate telomerase activity in bilharzial bladder cancer specimens and we correlated the findings with other clinical and pathological findings. Patients and methods: Bladder cancer specimens were obtained from 57 patients who underwent radical cystectomy and pathological diagnosis was obtained in all patients. Tissue samples were frozen in liquid nitrogen and stored at -80 degrees C. Telomerase activity by PCR-ELISA technique was measured using TRAP technique. Results: Our patient group included 45 males and 12 females with a median age of 49 years. The majority of our patients (35/57) have squamous histology and they have proven bilharzial history shown in the pathology specimens. Stage P3b was encountered in 29/57 patients whereas thirty-five patients have grade II tumors. The majority of our patients (41/57) were negative for pelvic nodes metastases. Telomerase activity was detected in 27/57 patients (47.4%). The mean level of telomerase was 0.85+/-0.77 in positive patients and 0.029+/-0.025 in negative patients. The expression of telomerase and its mean level in patients above age of 60, in males and in those with squamous pathology, higher grade of tumors or positive node was higher than those without but the difference did not reach statistical significance (P>0.05). Alternatively, expression was significantly higher in those with stages (P1-P3a) compared with P3b-P4a disease stages (66.6% vs. 37.1, P=0.03). Conclusion: Telomerase activity is increased in bilharzial bladder cancer although to a lesser degree than that reported for TCC in the western world, which could be explained, by different biological behavior or different assay methods. Further larger studies with more number of patients are still needed to determine its potential value for early detection and possible use as a therapeutic target.

Comparison of human telomerase reverse transcriptase messenger RNA and telomerase activity as urine markers for diagnosis of bladder carcinoma

BACKGROUND

Human telomerase reverse transcriptase (hTERT) has been identified as the catalytic subunit of telomerase ribonucleoprotein complex known to be required for cellular immortality and oncogenesis. Although human telomerase activity (hTA) is considered as a general marker for malignancy based on its presence in most malignant tumors including bladder cancer, its detection in urine is affected by many factors. The objective of this study was to compare the clinical utility of detecting urine hTERT messenger RNA (mRNA) by multiplex hTERT/GAPDH RT-PCR and urine hTA by telomerase repeat amplification protocol (TRAP) in the diagnosis of bladder cancer.

METHODS AND RESULTS

Cystoscopy urine samples or bladder washes prospectively collected from 35 patients with confirmed (35) or clinically suspected (5) transitional cell carcinoma (TCC) of the bladder were examined by TRAP, hTERT/GAPDH RT-PCR, and urine cytology. The control group comprised 21 healthy volunteers and 3 patients without TCC. The hTERT/GAPDH RT-PCR test showed significantly higher diagnostic sensitivity than TRAP assay (94.3% vs 48.6%, P <.001) and urine cytology (95.2% vs 61.9%, P =.008) for confirmed TCCs. In particular, for superficial TCCs low grade (I-II), the hTERT/GAPDH RT-PCR test outperformed TRAP (90% vs 25%, P <.001) and urine cytology (91.7% vs 58.3%, P =.46). The overall specificity of the hTERT/GAPDH RT-PCR, TRAP and urine cytology was 92% (22/24), 100% (24/24), and 100% (3/3), respectively. A positive hTERT mRNA expression was also detected in urologic specimens from 3 patients with previous history of TCC, 3 to 6 months before cystoscopic evidence of cancer.

CONCLUSION

In this pilot study, the hTERT mRNA expression in urine sediments is a more sensitive marker for diagnosis of TCC of the bladder than hTA and cytology. However, there is a higher false-positive rate.