Telomerase Activation inin Vitroandin VivoCervical Carcinogenesis

doi:10.1006/gyno.1997.4757

Gynecologic Oncology

Volume 66, Issue 2, August 1997, Pages 222-226

https://doi.org/10.1006/gyno.1997.4757 Get rights and content

Abstract

Telomerase activity is found in the majority of human cancers, but not in most normal tissues. It is generally accepted that there is a multistep process in human carcinogenesis. Studying the role of telomerase activation in this process may provide new information to further our understanding of the pathological process of clinical lesions. In the present study, telomerase activity was found in HPV-immortalized and cigarette smoke condensate (CSC)-transformed malignant cell lines established in a cervical carcinogenesis model and in cell lines derived from cervical intraepithelial neoplasias (CINs) and carcinomas. With exfoliated cell samples, telomerase activity was detected in 3 of 41 (7%) normal cervices, 10 of 25 (40%) CINs, and all 20 (100%) carcinomas. Telomerase activation was significantly higher in CINs than in normal cervices (χ²= 7.42,P< 0.01) and was much higher in invasive carcinomas than in CINs (χ²= 18.00,P< 0.005). Our observations suggest that telomerase activation is a relatively early-stage event in cervical carcinogenesis, and this activation is associated with the initiation and progression of cervical lesions. Detection of telomerase activity may serve as a tool for diagnosis and prognosis of cervical neoplasias.

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Novel semisynthetic triterpenoid AMR-Me inhibits telomerase activity in human leukemic CEM cells and exhibits in vivo antitumor activity against Dalton's lymphoma ascites tumor
2009, Cancer Letters
Citation Excerpt :
Elevated level of telomerase is a characteristic feature of cancer cells that leads to immortality. The activation of telomerase has been proposed to be a critical event in the cellular immortalization and is a characteristic of most human cancer cell lines and tumors [30–32]. Telomerase is not detectable in most somatic cells but is up-regulated in germ line cells and in human cancers, which suggests an important role of telomerase in neoplastic transformation.
Telomerase, a ribonucleoprotein complex of hTERT and hTER, has been reported to be associated with carcinogenesis and multidrug resistance (MDR). Methyl-25-hydroxy-3-oxoolean-12-en-28-oate (AMR-Me) is a novel semisynthetic triterpenoid, derived from a triterpene acid isolated from the stem bark of a tropical tree Amoora rohituka grown wild in India. We examined the role of telomerase in mediating the growth suppression of human acute lymphoblastic leukemic CEM cells by AMR-Me. The results showed that AMR-Me inhibited the growth and viability of CEM cells, induced apoptosis and cell cycle arrest in G₂+M phase. AMR-Me treatment resulted in suppression of hTERT expression and a concomitant inhibition of telomerase activity. The in vivo antitumor activity of AMR-Me was determined using mice inoculated with Dalton’s lymphoma ascites tumor cells. Intraperitoneal administration of the AMR-Me at doses of 1 or 3 mg/kg, increased the survival rate by 121% and 133% respectively, without weight change over the treatment period. Our results suggest that AMR-Me inhibits telomerase activity by decreasing the hTERT expression and induces apoptosis in human lymphoblastic leukemic CEM cells, thus providing the molecular basis for the development of AMR-Me as a novel chemotherapeutic agent against leukemia.
Genomic amplification of the human telomerase RNA gene for differential diagnosis of cervical disorders
2009, Cancer Genetics and Cytogenetics
Citation Excerpt :
Telomerase activation may be a relatively early event in cervical carcinogenesis, and this activation may be associated with the initiation and progression of cervical lesions. Telomerase activity and expression of its components may serve as biomarkers in diagnosis and prognosis of cervical neoplasias [13]. Different methods have been used to detect the expression or activity of telomerase or its components.
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 (χ² = 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.
Antiproliferative effects of the major tea polyphenol, (-)-epigallocatechin gallate and retinoic acid in cervical adenocarcinoma
2008, Gynecologic Oncology
Citation Excerpt :
These results were consistent with those of an antiproliferative effect of EGCG and/or RA in adenocarcinoma cells. The activation of telomerase has been proposed to be a critical event in the immortalization of human cells and is characteristic of most human cancer cell lines and tumors, including cervical cancer carcinogenesis [30–32]. It is reported that telomerase inhibition could be one of the major mechanisms in the anticancer effects of EGCG [20,33–36].
To investigate the combined effect of the major tea polyphenol, (−)-epigallocatechin gallate (EGCG) and retinoic acid (RA) on cervical adenocarcinoma.
Cell growth rate was examined after treatment for 4, 7 and 10 days with 0–100 μM EGCG and/or 1 μM RA in two cervical adenocarcinoma cell lines, HeLa and TMCC-1. The effect of EGCG treatment was examined for the induction of apoptosis by DNA ladder assay and caspase-3-related protease activity in cell lysate. Telomerase activity was detected by stretch PCR telomere extension assay. hTERT expression levels were quantified by a real-time PCR system.
Combining EGCG and RA increased the antiproliferative effect in adenocarcinoma cell lines, whereas EGCG or RA treatment alone caused a less sensitive response in these cells. Neither EGCG nor RA treatment alone affected apoptosis and telomerase activity. The combination treatment of EGCG and RA induced apoptosis and inhibited telomerase activity in adenocarcinoma cell lines. These results were consistent with those of an antiproliferative effect of EGCG and/or RA in cervical adenocarcinoma cells.
Our data suggest that EGCG and RA combined to prevent the carcinogenesis of cervical adenocarcinoma, induce apoptosis and inhibit telomerase activity. The treatments of combining EGCG and RA may be effective in preventing or treating cervical adenocarcinoma.
Chapter 2 Cellular and Molecular Biological Aspects of Cervical Intraepithelial Neoplasia
2008, International Review of Cell and Molecular Biology
Citation Excerpt :
Its gene is localized to chromosome 5 (5p15.33) (Harley et al., 1994). No telomerase activity is observed in normal cells and benign tumors but is induced in immortal and malignant cells (Skvortsov et al., 2006; Snijders et al., 1998; Sprague et al., 2002; Takahura et al., 1998; Van Duin et al., 2003; Wissman et al., 1998, 2000; Yashima et al., 1998; Zheng et al., 1997). In cervical carcinomas, this enzyme is induced by high‐risk HPV E6 so that these cancers have an additional factor favoring active proliferation of transformed cells (Klingelhutz et al., 1997; Renaud et al., 2007).
Cervical cancer is one of the most common cancers in women. The development of this disease involves reversible changes in the cervical tissue leading to various cellular abnormalities and ultimately to cervical cancer. Several well‐defined stages of cervical neoplasia are described, namely, precancer lesions and cancer. Squamous cell carcinomas and adenocarcinomas are most frequent among them, the former being much more common. Each stage is characterized by specific morphological changes. These changes were analyzed in the context of recent molecular biology data. Cervical carcinogenesis associated with infection with high‐risk human papillomaviruses (HPVs) contains several early genes that are necessary for viral replication and among them two genes (E6 and E7) play a key role in the induction of cervical carcinogenesis. The main targets of their products are tumor‐suppressor genes p53 and retinoblastoma, and their function is inhibited by E6 and E7 proteins. Both E6 and E7 are multifunctional and participate in many cellular functions associated with cell proliferation. The viral genome persists in transformed cells in episomal or integrated form (or both), and possible role of such type of persistence in tumor progression is discussed. Progression of the disease also involves many epigenetic changes. These include methylation of the genes relevant to cell proliferation and differentiation, activation of telomerase, and global changes in cellular gene expression. The cervical cancer is the first cancer that can be effectively prevented by vaccination.
The role of telomeres and telomerase in the pathology of human cancer and aging
2006, Pathology
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.
Telomerase and Human Papillomavirus as Diagnostic Adjuncts for Cervical Dysplasia and Carcinoma
2004, Human Pathology
Telomerase and human papillomavirus (HPV) DNA were evaluated as potential markers of high-grade dysplasia in cervical cytological specimens. Cytology specimens were collected from patients at the time of colposcopic evaluation for management of a previous abnormal cytology test result. Telomerase activity was evaluated by the telomeric repeat amplification protocol (TRAP), and HPV DNA was detected by polymerase chain reaction with L1 consensus-sequence primers and filter hybridization genotyping. Telomerase was detected in 8 of 97 (8.2%) cases with normal cytology or benign cellular changes, in 7 of 98 (7.1%) cases of atypical squamous cells of undetermined significance (ASCUS), in 3 of 95 (3.2%) cases of low-grade squamous intraepithelial lesion (LSIL), and in 17 of 48 (35.4%) cases with high-grade squamous intraepithelial lesion (HSIL). High-risk HPVs were detected in 23 of 97 (23.7%) cases with normal/reactive cellular changes (RCC) cytology, in 28 of 98 (28.6%) cases of ASCUS, in 69 of 95 (72.6%) cases of LSIL, and in 35 of 48 (72.9%) cases of HSIL. Telomerase expression did not correlate with the detection of high-risk HPVs in any cytological diagnostic categories. Telomerase and HPV test results of cytological specimens were correlated with the histological diagnoses of concurrent cervical biopsy specimens. Telomerase showed a sensitivity of 29.9% and a specificity of 94.0% for biopsy-confirmed cervical intraepithelial neoplasia (CIN) II/III. In contrast, high-risk HPVs were detected in 70.1% of cases with underlying CIN II/III, with a specificity of 62.5%. A relatively high proportion of normal/RCC or ASCUS cases with telomerase-positive test results had underlying high-grade dysplasia on cervical biopsy. Thus, technical and practical limitations of the TRAP assay in cervical cytology specimens limit the practical application of telomerase as a diagnostic adjunct in cervical cytopathology.

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Regular ArticleTelomerase Activation inin Vitroandin VivoCervical Carcinogenesis

Abstract

Cell

Gynecol Oncol

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Gynecol Oncol

The human telomere terminal transferase enzyme is a ribonucleoprotein that synthesizes TTAGGG repeats

Cell

Structure and function of telomeres

Nature

Loss of telomeric DNA during aging of normal and trisomy 21 human lymphocytes

Am J Hum Genet

Evidence for a mitotic clock in human hematopoietic stem cells, loss of telomeric DNA with age

Proc Natl Acad Sci USA

The telomere hypothesis of cellular ageing

Exp Gerontol

Telomere length predicts replicative capacity of human fibroblasts

Proc Natl Acad Sci USA

Telomere shortening associated with chromosome instability is arrested in immortal cells which express telomerase activity

EMBO J

Stabilization of short telomeres and telomerase activity accompany immortalization of Epstein–Barr virus-transformed human B lymphocytes

J Virol

Telomeres, telomerase, and immortality

J Natl Cancer Inst

Specific association of human telomerase activity with immortal cells and cancer

Science

Telomere dynamics and telomerase activation in tumor progression: prospects for prognosis and therapy

Oncol Res

Estimates of the worldwide incidence of eighteen major cancers in 1985

Int J Cancer

Oncogenes, antioncogenes, and the molecular bases of multistep carcinogenesis

Cancer Res

Genetic analysis of in vitro progression of human papillomavirus-transfected human cervical cells

Cancer Res

Epithelial Tumours and Related Lesions

Histological Typing of Female Genital Tract Tumours

Oral contraceptive use, human papillomavirus infection, and risk of early cytological abnormalities of the cervix

Cancer Res

Persistent genital human papillomavirus infection as a risk factor for persistent cervical dysplasia

J Natl Cancer Inst

Regular Article
Telomerase Activation inin Vitroandin VivoCervical Carcinogenesis