Telomerase Activity as a Potential Diagnostic Marker for Triage of Abnormal Pap Smears

Correlation of hTERT Expression with Cervical Cytological Abnormalities and Human Papillomavirus Infection

Telomerase Reverse Transcriptase (TERT) is the main catalytic sub-unit of telomerase, a reverse transcriptase enzyme. Telomerase expression is regulated at many levels, with numerous studies suggesting that up-regulation of human TERT gene (hTERT) at transcriptional level results in immortal cell phenotype associated with cancer. The aim of this study is to determine the correlation between hTERT expression and different cervical precursor lesions, as well as with cervical cancer in patients with confirmed Human papillomavirus (HPV) infection. The study included molecular analyzes on cervical samples from 214 women and matched Papanicolaou (Pap) test results. HPV detection and genotyping was performed by polymerase chain reaction (PCR) and genotyping. Quantitative real-time PCR (qRT-PCR) was performed using TaqMan probes and were calculated relative to the reference gene. Results showed significantly increased hTERT mRNA expression levels in high-grade and low-grade lesions compared to normal control samples (p<0.01) associated with 6.31 fold higher risk for developing ASC-US and 9.20 for LSIL. Strong correlation between HPV infection and hTERT expression in the high-grade lesions and cervical cancer was also observed. hTERT relative expression values showed 98% specificity and 100 % sensitivity as indicator of cervical lesions particularly for the ACS-H, HSIL and cervical cancer. In conclusion, hTERT expression correlate with the cytological grade of the cervical lesions and HPV infection and has a potential to be used as a diagnostic and prognostic marker.

Telomerase activity in cervical scrapes of women with high-grade cervical disease: A nested case-control study

Epidemiological information on telomerase activity (TA) and development of cervical lesions is scarce. A nested case-control study was carried out within a cohort of Colombian women tested for Human Papillomavirus (HPV). Measurement of TA was done in cervical scrapes of 25 women who developed High Grade Squamous Intraepithelial Lesion (HGSIL) during the first 6 years of follow-up and was compared with that of 104 control women who maintained normal cytology during the entire follow-up. TA was measured by a telomerase repeat amplification protocol-ELISA. TA and HPV infections were significantly more frequent in cases than in controls. Likewise, 68% of the cases were positive for both TA and HPV compared with only 7.7% of the controls (P<0.0001). Factors independently associated with increased odds of HGSIL included TA, high risk HPV (hrHPV) infections and multiple parities. When restricted to hrHPV positive women, TA was strongly associated with increased odds of HGSIL (adjusted odds ratio=37.94, 95% confidence interval, 1.64–678.1). In addition to an infection with hrHPV, TA appears to be a significant cofactor for HGSIL.

The Application of Classification and Regression Trees for the Triage of Women for Referral to Colposcopy and the Estimation of Risk for Cervical Intraepithelial Neoplasia: A Study Based on 1625 Cases with Incomplete Data from Molecular Tests

OBJECTIVE

Nowadays numerous ancillary techniques detecting HPV DNA and mRNA compete with cytology; however no perfect test exists; in this study we evaluated classification and regression trees (CARTs) for the production of triage rules and estimate the risk for cervical intraepithelial neoplasia (CIN) in cases with ASCUS+ in cytology.

STUDY DESIGN

We used 1625 cases. In contrast to other approaches we used missing data to increase the data volume, obtain more accurate results, and simulate real conditions in the everyday practice of gynecologic clinics and laboratories. The proposed CART was based on the cytological result, HPV DNA typing, HPV mRNA detection based on NASBA and flow cytometry, p16 immunocytochemical expression, and finally age and parous status.

RESULTS

Algorithms useful for the triage of women were produced; gynecologists could apply these in conjunction with available examination results and conclude to an estimation of the risk for a woman to harbor CIN expressed as a probability.

CONCLUSIONS

The most important test was the cytological examination; however the CART handled cases with inadequate cytological outcome and increased the diagnostic accuracy by exploiting the results of ancillary techniques even if there were inadequate missing data. The CART performance was better than any other single test involved in this study.

Human papillomavirus 16E6 and NFX1-123 potentiate Notch signaling and differentiation without activating cellular arrest

High-risk human papillomavirus (HR HPV) oncoproteins bind host cell proteins to dysregulate and uncouple apoptosis, senescence, differentiation, and growth. These pathways are important for both the viral life cycle and cancer development. HR HPV16 E6 (16E6) interacts with the cellular protein NFX1-123, and they collaboratively increase the growth and differentiation master regulator, Notch1. In 16E6 expressing keratinocytes (16E6 HFKs), the Notch canonical pathway genes Hes1 and Hes5 were increased with overexpression of NFX1-123, and their expression was directly linked to the activation or blockade of the Notch1 receptor. Keratinocyte differentiation genes Keratin 1 and Keratin 10 were also increased, but in contrast their upregulation was only indirectly associated with Notch1 receptor stimulation and was fully unlinked to growth arrest, increased p21(Waf1/CIP1), or decreased proliferative factor Ki67. This leads to a model of 16E6, NFX1-123, and Notch1 differently regulating canonical and differentiation pathways and entirely uncoupling cellular arrest from increased differentiation.

Telomerase Activity as a Tumor Marker in Indian Women with Cervical Intraepithelial Neoplasia and Cervical Cancer

BACKGROUND AND OBJECTIVES

Cervical cancer is the most common cancer in Indian women and is a leading cause of death in women worldwide. Cervical cancer develops from pre-neoplastic cervical intraepithelial neoplasia (CIN). This study was conducted to evaluate telomerase activity as a tumor marker for the detection of cancer in patients with CIN and cervical cancer. The results were compared with human papillomavirus (HPV) status, clinical staging, and histopathologic studies.

METHODS

Telomerase activity was detected using the PCR-based telomeric repeat amplification protocol (TRAP) assay in cervical tissues collected by routine punch biopsy from the uterine cervix of patients with suspected cervical cancer. High-risk (HR) HPV-16 and -18 status was determined in all the study groups, including controls. A total of 125 patients (including 50 patients with CIN and 75 patients with cervical cancer [including nine patients with adeno-squamous disease]) and 22 control subjects were studied. The sensitivity and specificity for detecting CIN and cervical cancer were calculated.

RESULTS

Patients with grade I, II, and III CIN showed 17%, 33%, and 57% positivity for telomerase, respectively. In patients with cervical cancer, those at early clinical stages (Ia-IIb) showed 68% positivity and those at later clinical stages showed 92% positivity for telomerase activity. In the present study, telomerase positivity correlated significantly with the detection of HR HPV-16 and -18 (p < 0.001). As a diagnostic test, none of the described analyses combined a sensitivity of > or =90% with a specificity of > or =90%, except in patients with advanced cancer when telomerase activity was used as a diagnostic test.

CONCLUSION

Our findings suggest that telomerase activation is a relatively early event in cervical carcinogenesis and correlates with the grade of cervical lesion, HR-HPV status (16 and 18 subtypes), and clinical staging. Hence, these associations suggest it as a possible target for detection of cervical cancer.

Cancer stem cells and telomerase as potential biomarkers in veterinary oncology

Despite advances in chemotherapy and radiotherapy, cancer remains a disease of high morbidity and mortality in domestic animals. In parallel to the development of novel therapeutic interventions, appropriate biomarkers are required to detect early-stage disease and disease remission and relapse at both gross and molecular levels, and the effectiveness of therapy. The field of cancer pathogenesis has grown exponentially over the last decade, both in terms of our understanding of the underlying molecular events, and the technologies available to interrogate the cancer cell. This paper reviews the role of the telomerase enzyme and of telomere length as potential biomarkers in cancer. Furthermore, the potential role of cancer stem cells as biomarkers of malignancy and disease progression is assessed.

Genomic amplification of the human telomerase RNA gene for differential diagnosis of cervical disorders

To evaluate genomic amplification of the human telomerase RNA gene (TERC) as a supportive approach to cytopathology or histopathology in diagnosis of low-grade and high-grade uterine cervical lesions, 1,033 Chinese women at three medical centers had liquid-based thin-layer cytopathologic examination and TERC detection by fluorescence in situ hybridization (FISH). Human papillomavirus DNA testing, colposcopy with or without biopsy, and histopathologic examination were conducted as needed. In cytopathologic examination, genomic amplification of TERC was found in 30 of 659 (4.6%) normal or benign cellular changes; in 23 of 170 (13.5%) atypical squamous cells of undetermined significance (ASCUS); in 8 of 28 (28.6%) atypical squamous cells with high-grade squamous intraepithelial lesion possible (ASC-H); and in 26 of 103 (25.2%) low-grade (LSIL) and 64 of 73 (87.7%) high-grade (HSIL) squamous intraepithelial lesions; with pairwise significant difference (P< 0.05) in each, except ASC-H and LSIL (chi(2) = 0.127, P = 0.72). In histopathologic examination, TERC was amplified in 28 of 671 (4.2%) normal, inflammatory, or wart cases; in 17 of 233 (7.3%) cervical intraepithelial neoplasia grade 1 cases (CIN 1); in 27 of 39 (69.2%) CIN 2 cases; in 57 of 67 (85.1%) CIN 3 cases; and in 22 of 23 (95.7%) cervical cancer cases; with pairwise significant difference in each (P < 0.05). The number of cells with abnormal signals increased and the abnormal signal patterns were diversified with increasing severity of cervical dysplasia. FISH detection of TERC amplification may provide an effective, noninvasive approach in conjunction with cytopathologic or histopathologic evaluation for differential diagnosis of low- and high-grade cervical disorders.

The role of telomeres and telomerase in the pathology of human cancer and aging

Cellular senescence, the state of permanent growth arrest, is the inevitable fate of replicating normal somatic cells. Postulated to underlie this finite replicative span is the physiology of telomeres, which constitute the ends of chromosomes. The repetitive sequences of these DNA-protein complexes progressively shorten with each mitosis. When the critical length is bridged, telomeres trigger DNA repair and cell cycle checkpoint mechanisms that result in chromosomal fusions, cell cycle arrest, senescence and/or apoptosis. Should senescence be bypassed at such time, continued cell divisions in the face of dysfunctional telomeres and activated DNA repair machinery can result in the genomic instability favourable for oncogenesis. The longevity and malignant progression of the thus transformed cell requires coincident telomerase expression or other means to negate the constitutional telomeric loss. Practically then, telomeres and telomerase may represent plausible prognostic and screening cancer markers. Furthermore, if the argument is extended, with assumptions that telomeric attrition is indeed the basis of cellular senescence and that accumulation of the latter equates to aging at the organismal level, then telomeres may well explain the increased incidence of cancer with human aging.