Telomerase activity in gynecologic tumors

Telomerase and Telomeres in Endometrial Cancer

Telomeres at the termini of human chromosomes are shortened with each round of cell division due to the “end replication problem” as well as oxidative stress. During carcinogenesis, cells acquire or retain mechanisms to maintain telomeres to avoid initiation of cellular senescence or apoptosis and halting cell division by critically short telomeres. The unique reverse transcriptase enzyme complex, telomerase, catalyzes the maintenance of telomeres but most human somatic cells do not have sufficient telomerase activity to prevent telomere shortening. Tissues with high and prolonged replicative potential demonstrate adequate cellular telomerase activity to prevent telomere erosion, and high telomerase activity appears to be a critical feature of most (80–90%) epithelial cancers, including endometrial cancer. Endometrial cancers regress in response to progesterone which is frequently used to treat advanced endometrial cancer. Endometrial telomerase is inhibited by progestogens and deciphering telomere and telomerase biology in endometrial cancer is therefore important, as targeting telomerase (a downstream target of progestogens) in endometrial cancer may provide novel and more effective therapeutic avenues. This review aims to examine the available evidence for the role and importance of telomere and telomerase biology in endometrial cancer.

Metformin use and gynecological cancers: A novel treatment option emerging from drug repositioning

Metformin exerts antitumor effects mainly through AMP-activated protein kinase [AMPK] activation and phosphatidylinositol 3-kinase [PI3K]-Akt-mammalian target of rapamycin [mTOR] inhibition. This drug leads to activation of the cellular energy-sensing liver kinase B1 [LKB1]/AMPK pathway. LKB1 is implicated as a tumor suppressor gene in molecular pathogenesis of different malignancies. AMPK is a serine/threonine protein kinase that acts as an ultra-sensitive cellular energy sensor maintaining the energy balance within the cell. AMPK activation inhibits mRNA translation and proliferation in cancer cells via down-regulation of PI3K/Akt/mTOR pathway. Moreover, metformin decreases the production of insulin, insulin-like growth factor, inflammatory cytokines and vascular endothelial growth factor, and therefore it exerts anti-mitotic, anti-inflammatory and anti-angiogenetic effects. Recent in vitro and experimental data suggest that metformin electively targets cancer stem cells, and acts together with chemotherapy to block tumor growth in different cancers. Several epidemiological studies and meta-analysis have shown that metformin use is associated with decreased cancer risk and/or reduced cancer mortality for different malignancies. The present review analyzes the recent biological and clinical data suggesting a possible growth-static effect of metformin also in gynecological cancers. The large majority of available clinical data on the anti-cancer potential of metformin are based on observational studies. Therefore long-term phase II-III clinical trials are strongly warranted to further investigate metformin activity in gynecological cancers.

Telomeres and human reproduction

Telomeres mediate biologic aging in organisms as diverse as plants, yeast, and mammals. We propose a telomere theory of reproductive aging that posits telomere shortening in the female germ line as the primary driver of reproductive aging in women. Experimental shortening of telomeres in mice, which normally do not exhibit appreciable oocyte aging, and which have exceptionally long telomeres, recapitulates the aging phenotype of human oocytes. Telomere shortening in mice reduces synapsis and chiasmata, increases embryo fragmentation, cell cycle arrest, apoptosis, spindle dysmorphologies, and chromosome abnormalities. Telomeres are shorter in the oocytes from women undergoing in vitro fertilization, who then produce fragmented, aneuploid embryos that fail to implant. In contrast, the testes are replete with spermatogonia that can rejuvenate telomere reserves throughout the life of the man by expressing telomerase. Differences in telomere dynamics across the life span of men and women may have evolved because of the difference in the inherent risks of aging on reproduction between men and women. Additionally, growing evidence links altered telomere biology to endometriosis and gynecologic cancers, thus future studies should examine the role of telomeres in pathologies of the reproductive tract.

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.

Metformin potentiates the effects of paclitaxel in endometrial cancer cells through inhibition of cell proliferation and modulation of the mTOR pathway

OBJECTIVES

To examine the effects of combination therapy with metformin and paclitaxel in endometrial cancer cell lines.

METHODS

ECC-1 and Ishikawa endometrial cancer cell lines were used. Cell proliferation was assessed after exposure to paclitaxel and metformin. Cell cycle progression was assessed by flow cytometry. hTERT expression was determined by real-time RT-PCR. Western immunoblotting was performed to determine the effect of metformin/paclitaxel on the mTOR pathway.

RESULTS

Paclitaxel inhibited proliferation in a dose-dependent manner in both cell lines with IC(50) values of 1-5nM and 5-10nM for Ishikawa and ECC-1 cells, respectively. Simultaneous exposure of cells to various doses of paclitaxel in combination with metformin (0.5mM) resulted in a significant synergistic anti-proliferative effect in both cell lines (Combination Index<1). Metformin induced G1 arrest in both cell lines. Paclitaxel alone or in combination with metformin resulted in predominantly G2 arrest. Metformin decreased hTERT mRNA expression while paclitaxel alone had no effect on telomerase activity. Metformin stimulated AMPK phosphorylation and decreased phosphorylation of the S6 protein. In contrast, paclitaxel inhibited AMPK phosphorylation in the ECC-1 cell line and induced phosphorylation of S6 in both cell lines. Treatment with metformin and paclitaxel resulted in decreased phosphorylation of S6 in both cell lines but only had an additive effect on AMPK phosphorylation in the ECC-1 cell line.

CONCLUSIONS

Metformin potentiates the effects of paclitaxel in endometrial cancer cells through inhibition of cell proliferation and modulation of the mTOR pathway. This combination may be a promising targeted therapy for endometrial cancer.

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.

Rapamycin inhibits cell proliferation in type I and type II endometrial carcinomas: a search for biomarkers of sensitivity to treatment

OBJECTIVES

Our goal was to evaluate the effect of rapamycin, an mTOR inhibitor, in type I and II human endometrial cancer tumor explants.

METHODS

Short-term tissue culture with fresh endometrial cancer tumor explants was performed. Cell proliferation was assessed by MTS assay after treatment with rapamycin. Akt and PTEN status were documented by Western blotting. The effect of rapamycin on phosphorylated-S6 and 4E-BP-1 was also assessed by Western blotting. Real-time RT-PCR was used to quantify hTERT mRNA expression. Telomere length was determined by terminal restriction fragment Southern blotting.

RESULTS

Thirteen fresh endometrial cancer tumor explants (nine Type I, four Type II) were placed in short-term culture and treated with rapamycin. Nine of the endometrial cancer tumors responded to rapamycin, with a median IC₅₀ of 11.4 nM. Sensitivity to rapamycin was independent of PTEN and Akt status. Tumors (13/13) had a reduction in phosphorylated-S6 and 10/13 had a reduction in phosphorylated 4E-BP-1. Rapamycin decreased hTERT mRNA expression in all of the endometrial cancer tumors. Telomere length did not correspond with responsiveness to this drug.

CONCLUSIONS

Rapamycin demonstrated activity in fresh endometrial tumor explants independent of PTEN and Akt status. Some tumors demonstrated a reduction in phosphorylated-S6 and 4E-BP-1 without a significant change in cellular proliferation, suggesting that additional pathways may modulate cellular proliferation. Thus, mTOR inhibitors may be a useful targeted therapy for both type I and type II endometrial cancers, but the search remains for a predictive biomarker of sensitivity to this therapy.

Rapamycin potentiates the effects of paclitaxel in endometrial cancer cells through inhibition of cell proliferation and induction of apoptosis

Mammalian target of rapamycin (mTOR) inhibitors modulate signaling pathways involved in cell cycle progression, and recent phase II trials demonstrate activity in patients with endometrial cancer. Our objective was to examine the effects of combination therapy with rapamycin and paclitaxel in endometrial cancer cell lines. Paclitaxel inhibited proliferation in a dose-dependent manner in both cell lines with IC(50) values of 0.1-0.5 nM and 1-5 nM for Ishikawa and ECC-1 cells, respectively. To assess synergy of paclitaxel and rapamycin, the combination index (CI) was calculated by the method of Chou and Talalay. Simultaneous exposure of cells to various doses of paclitaxel in combination with rapamycin (1 nM) resulted in a significant synergistic anti-proliferative effect (CI <1, range 0.131-0.920). Rapamycin alone did not induce apoptosis, but combined treatment with paclitaxel increased apoptosis over that of paclitaxel alone. Treatment with rapamycin and paclitaxel resulted in decreased phosphorylation of S6 and 4E-BP1, two critical downstream targets of the mTOR pathway. Rapamycin decreased hTERT mRNA expression by real-time RT-PCR while paclitaxel alone had no effect on telomerase activity. Paclitaxel increased polymerization and acetylation of tubulin, and rapamycin appeared to enhance this effect. Thus, in conclusion, we demonstrate that rapamycin potentiates the effects of paclitaxel in endometrial cancer cells through inhibition of cell proliferation, induction of apoptosis and potentially increased polymerization and acetylation of tubulin. This suggests that the combination of rapamycin and paclitaxel may be a promising effective targeted therapy for endometrial cancer.

Metformin is a potent inhibitor of endometrial cancer cell proliferation--implications for a novel treatment strategy

OBJECTIVES

Obesity and diabetes are strong risk factors that drive the development of type I endometrial cancers. Recent epidemiological evidence suggests that metformin may lower cancer risk and reduce rates of cancer deaths among diabetic patients. In order to better understand metformin's anti-tumorigenic potential, our goal was to assess the effect of metformin on proliferation and expression of key targets of metformin cell signaling in endometrial cancer cell lines.

METHODS

The endometrial cancer cell lines, ECC-1 and Ishikawa, were used. Cell proliferation was assessed after exposure to metformin. Cell cycle progression was evaluated by flow cytometry. Apoptosis was assessed by ELISA for caspase-3 activity. hTERT expression was determined by real-time RT-PCR. Western immunoblotting was performed to determine the expression of the downstream targets of metformin.

RESULTS

Metformin potently inhibited growth in a dose-dependent manner in both cell lines (IC(50) of 1 mM). Treatment with metformin resulted in G1 arrest, induction of apoptosis and decreased hTERT expression. Western immunoblot analysis demonstrated that metformin induced phosphorylation of AMPK, its immediate downstream mediator, within 24 h of exposure. In parallel, treatment with metformin decreased phosphorylation of S6 protein, a key target of the mTOR pathway.

CONCLUSIONS

We find that metformin is a potent inhibitor of cell proliferation in endometrial cancer cell lines. This effect is partially mediated through AMPK activation and subsequent inhibition of the mTOR pathway. This work should provide the scientific foundation for future investigation of metformin as a strategy for endometrial cancer prevention and treatment.

Antiproliferative effects of the major tea polyphenol, (-)-epigallocatechin gallate and retinoic acid in cervical adenocarcinoma

OBJECTIVE

To investigate the combined effect of the major tea polyphenol, (-)-epigallocatechin gallate (EGCG) and retinoic acid (RA) on cervical adenocarcinoma.

METHODS

Cell growth rate was examined after treatment for 4, 7 and 10 days with 0-100 microM EGCG and/or 1 microM 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.

RESULTS

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.

CONCLUSION

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.

Telomerase activity as an adjunct to high-risk human papillomavirus types 16 and 18 and cytology screening in cervical cancer

Telomerase is a ribonucleoprotein comprising an RNA template, the telomerase-associated protein and its catalytic subunit, human telomerase reverse transcriptase (hTERT). Telomerase activation is a critical step in cellular immortalisation and development of cancer. Enhanced telomerase activity has been demonstrated in cervical cancer. In the present study telomerase activity and hTERT mRNA expression were evaluated and correlated with the presence of human papillomavirus (HPV) infection and cytological changes in the cervical lesions. Telomerase activity was assayed by telomeric repeat amplification protocol, hTERT mRNA expression by reverse transcriptase polymerase chain reaction and presence of high risk HPV (HR-HPV) infection by polymerase chain reaction. Out of 154 cervical samples of different cytology, 90 (58.44%) were positive for HR-HPV types 16/18, while among 55 normal cervical scrapes, 10 (18.18%) were HPV DNA positive. All 59 invasive cancer samples showed a very high telomerase activity. Among dysplasia, seven (63.6%) mild dysplasia, 18 (100%) of moderate, 20 (100%) of severe dysplasia and 6 (100%) carcinoma in situ (CIS) samples were positive with mild to moderate to high to very high telomerase activity respectively. Seven (12.7%) samples of apparently normal cervical scrapes were weakly positive for telomerase activity. We observed a good correlation (P<0.001) between telomerase activity and HR-HPV 16/18 positivity with a sensitivity of 88.1% for HPV and 100% for telomerase activity. It is suggested that telomerase activity may be used as an adjunct to cytology and HPV DNA testing in triaging women with cervical lesions.

Estrogen-receptor-dependent regulation of telomerase activity in human endometrial cancer cell lines

OBJECTIVES

Given that prolonged exposure to unopposed estrogen is associated with endometrial cancer development and that the promoter region of the catalytic subunit of the telomerase enzyme, hTERT, contains putative estrogen response elements (EREs), we postulated that estrogen-receptor (ER)-mediated induction of telomerase activity may play an important role in endometrial carcinogenesis.

METHODS

ER-positive and ER-negative endometrial cancer cell lines were used. ER alpha expression was reconstituted in ER-negative cell lines by transient transfection. Telomerase activity was assayed using a PCR-based telomeric repeat amplification protocol (TRAP) after exposure to estradiol (E2). hTERT mRNA expression was assessed by real-time RT-PCR. Gel shift assays using oligonucleotide probes encoding each ERE and transient expression assays using luciferase reporter plasmids containing varying lengths of the 5' promoter region of the hTERT gene were performed.

RESULTS

E2 induced both hTERT gene transcription and telomerase activity in the ER-positive cell lines, but not in the ER-negative cell lines. Transfection of ER alpha into ER-negative cell lines restored E2-induced hTERT gene transcription and telomerase activity. Gel shift assays revealed two EREs in the hTERT promoter that specifically bind to ER alpha. Luciferase assays demonstrated that at least the proximal ERE is responsible for transcriptional activation by ligand-stimulated ER alpha.

CONCLUSIONS

Telomerase activity and hTERT mRNA were increased in response to estrogen in an ER alpha-dependent fashion in endometrial cancer cells. Binding of complexed estrogen with ER alpha to the EREs found within the hTERT promoter suggests a possible mechanism for telomerase induction that may facilitate the malignant transformation of hormone-dependent endometrial cells.

Screening for gynaecological cancers

BACKGROUND

The role of screening in gynaecological cancers is under evaluation. With mass screening proven effective in significantly reducing cervical cancer mortality, there is an interest in developing other screening methods to detect gynaecological malignancies early. This review covers advances in cervical cancer screening, strategies being investigated in ovarian cancer screening and the lack of justification in screening for endometrial, vulval and vaginal cancers.

METHODS

A Medline based literature search was performed for articles relating to screening for different gynaecological malignancies. Additional original papers cited in those identified by the initial search were also reviewed.

RESULTS

Advances in cervical cancer screening include liquid-based cytology and HPV testing. Results of ongoing trials are awaited before these can be fully implemented. The results of the two large, multicentre, randomised controlled trials being conducted in the United Kingdom and United States (UKCTOCS and PLCO study, respectively) to assess impact of screening on ovarian cancer mortality will shed some light on the need to implement screening for ovarian cancer in the general population. Novel markers, serum proteomic profiles and Doppler are some of the other technologies being explored. Currently, screening for endometrial cancer is not advocated as most women present with symptoms in early disease with good survival outcomes. Vulval and vaginal cancers are too rare to justify mass screening.

CONCLUSION

Methods to screen for various gynaecological malignancies need further evaluation before implementation in the general population. Results of large multicentred trials are awaited. Presently, screening for endometrial, vaginal and vulval cancers is not justified.

Rapamycin inhibits hTERT telomerase mRNA expression, independent of cell cycle arrest

OBJECTIVES

Rapamycin and its analogues have been shown to be promising as anti-neoplastic agents but have not been extensively studied in gynecologic malignancies. Our goal was to examine the ability of rapamycin to suppress growth and regulate telomerase activity in cervical and ovarian cancer cell lines.

METHODS

Cell proliferation was assessed after exposure to rapamycin. Cell cycle progression was determined by flow cytometry, and apoptosis was evaluated by DNA fragmentation. hTERT mRNA levels were quantified by real-time RT-PCR. Western blot analysis was performed to assess PTEN status, phosphorylated S6 and total S6 expression.

RESULTS

Rapamycin inhibited growth of all the cervical cancer cell lines and 3 of the 4 ovarian cancer cell lines in a dose-dependent manner with IC50 values <50 nM. Loss of PTEN protein expression was seen in only one of the cervical cancer cell lines. Rapamycin induced G1 arrest in those cell lines sensitive to its growth inhibitory effects. In all cell lines, rapamycin rapidly inhibited phosphorylation of S6 and resulted in decreased levels of total S6 protein. Treatment with rapamycin reduced hTERT mRNA expression in both rapamycin-sensitive and -resistant cell lines within 24 h. Thus, the effect of rapamycin on hTERT expression was not dependent on its ability to induce G1 cell cycle arrest.

CONCLUSIONS

Our data suggest that rapamycin may potentially exert its anti-tumor effects through two independent pathways by G1 cell cycle arrest as well as suppression of telomerase activity by inhibition of hTERT mRNA transcription.

Human telomerase RNA as endogenous control in endometrial tissue

Telomerase is a reverse transcriptase that adds repetitive telomere sequences to the end of chromosomes, which is thought to be essential for cellular immortality and oncogenesis. The enzyme consists of three subunits: human telomerase reverse transcriptase (hTERT), human telomerase RNA (hTR), and telomerase protein 1 (TP1). The hTERT subunit determines the activity of telomerase as an enzyme and is detected in most human tumors and regenerative cells. But many studies have revealed that hTR and TP1 are expressed constitutively. This results suggest that the hTR and TP1 subunits may be potentially good markers of endogenous RNA control. Endometrial dating was determined from the pathomorphology of the endometrium and classified into normal proliferative endometrium, endometrial hyperplasia (simple, complex, and atypical), and endometrial adenocarcinoma. The analysis of the expression of the hTERT, TP1, and hTR telomerase subunits was performed by a quantitative polymerase chain reaction method, based on fluorescent TaqMan methodology (ABI Prism 7,700 Sequence Detection System) capable of measuring fluorescence in real time. The aim of the study was an analysis of the expression profiles of genes encoding hTR and TP1 telomerase subunits in normal endometrium, endometrial hyperplasia, and adenocarcinoma for the estimation of the possibility of once application in endogenous RNA control of gene analysis in the endometrium. The nonparametric Mann-Whitney U test and analysis of variance Friedman test were used to evaluate the variation in telomerase subunit mRNA level between normal endometrium, and endometrial hyperplasia and adenocarcinoma. The results confirm the hTR subunit expression as a good marker of endogenous control in quantitative analysis of gene transcription in endometrial tissue. TP1 subunit transcriptions have not been detected constitutively in our study.

Immunohistochemical Detection of Human Telomerase Reverse Transcriptase (hTERT), Topoisomerase II?? Expression, and Apoptosis in Endometrial Adenocarcinoma and Atypical Hyperplasia

This study evaluated the immunohistochemical expression of human telomerase reverse transcriptase (hTERT) in endometrial carcinoma and atypical endometrial hyperplasia, and related it to the expression of topoisomerase (TP)IIalpha (a proliferation associated enzyme); apoptosis as determined by the frequency of apoptotic bodies (ABI); mitotic counts; and other clinicopathologic variables. Immunoreactivity for hTERT and TPIIalpha as well as ABI were assessed in 57 endometrial samples (12 atypical hyperplasias, 33 endometrioid carcinomas, 12 serous/clear cell carcinomas). hTERT immunoreactivity, TPIIalpha labeling indices (LI), ABI, and ratios of the indices (ABI/TPIIalpha LI) increased from atypical hyperplasias to endometrioid carcinomas to serous/clear cell carcinomas (p < 0.0001 for each variable). hTERT expression increased with ABI (p < 0.0001), TPIIalpha LI (p = 0.0019), ABI/TPIIalpha ratios (p < 0.0001), and grade (p = 0.0005), but not with FIGO stage (p = 0.2775). TPIIalpha LI, ABI, and ratios were related to high grade (p = 0.0001 for each variable), but not with FIGO stage (p = 0.7362, p = 0.7554, and p = 0.7405, respectively). TPIIalpha LI and ABI were significantly correlated in atypical hyperplasias (p = 0.0004), endometrioid carcinomas (p < 0.0001), and serous/clear cell carcinomas (p = 0.024). Immunostaining levels for hTERT were similar in atypical hyperplasias and grade 1 endometrioid carcinomas (p = 0.1956). These results suggest that hTERT expression is closely related to proliferation, apoptosis, and high grade in endometrial carcinomas, reflecting cell cycle deregulation in endometrial carcinogenesis.

Sertoli-Leydig cell tumor - a rare androgen secreting ovarian tumor in postmenopausal women. Case report and review of literature

Sertoli-Leydig cell tumors (SLCT) constitute only 1-0.5% of all primary ovarian neoplasms. We report a SLCT in a postmenopausal woman aged 69 years. The physical examination revealed severe hirsutism. Basal hormonal evaluation showed high plasma testosterone and estradiol values, with suppressed plasma gonadotropins. Computer tomograph scan revealed a right ovarian tumor mass of 4,3/3 cm, confirming an androgen secreting ovarian tumor. The histopathological and immunocytochemical examination established the diagnosis of well differentiated Sertoli-Leydig cell tumor. The tumor was positive for cytokeratin KL 1 and S-100 protein and, in isolated tumor cells, positive for alpha-fetoprotein. Postsurgical evolution was favorable; controls after 6 months and 3,5 years showed marked reduction of hirsutism, normal plasma testosterone values and gonadotropins in normal postmenopausal range. We discuss the complex aspects of etiology and pathogenesis, the clinical and hormonal settings, the role of immunocytochemical markers in diagnosis, as well as the therapy and the prognostic features of this ovarian tumor.

Expression of human telomerase reverse transcriptase in lymphangioleiomyomatosis

Telomerase synthesizes nucleotide hexameric repeats (telomeres) at the ends of chromosomes, replacing base sequences that are lost from these sites during each mitotic cycle and protecting these ends against the action of exonucleases and ligases. Therefore, telomerase is essential for maintaining cellular replication. To evaluate the role of telomerase in the proliferation of abnormal smooth muscle cells (lymphangioleiomyomatosis [LAM] cells) in LAM, we performed immunostaining and in situ hybridization studies to identify telomerase protein and messenger RNA (mRNA), respectively, in pulmonary (n = 18) and extrapulmonary (n = 4) lesions from 22 women with LAM (14 untreated and 8 treated with progesterone or tamoxifen). Immunoreactivity and hybridization signals for telomerase were observed in 5 to 20% of LAM cells, mostly of the spindle-shaped type, in 21 of the 22 patients, and were less intense in the treated group. Other types of cells were unreactive in both groups. Telomerase colocalized in the same cells with alpha-smooth muscle actin, but only rarely with HMB-45 antibody (a marker for epithelioid LAM cells); colocalization with proliferating cell nuclear antigen was incomplete. The telomerase-positive LAM cells may constitute the sources of renewal of LAM cells. Modulation of telomerase may be involved in the control of LAM cell proliferation.

Immortalization of human uterine leiomyoma and myometrial cell lines after induction of telomerase activity: molecular and phenotypic characteristics

In vitro model systems for studying uterine leiomyomas are limited in that human-derived leiomyoma cells grow poorly in culture compared with normal myometrial cells and begin to senesce early, at approximately passage 10 in our studies. To our knowledge, a good in vitro human-derived cell culturing system for leiomyomas does not exist. In an attempt to fill this void, we have immortalized a uterine leiomyoma cell line by inducing telomerase activity, which allows cells to bypass their normal programmed senescence. Telomerase activity was induced by infecting the target (uterine leiomyoma and normal myometrial) cells with a retroviral vector containing hTERT, the gene for the catalytic subunit of telomerase. Subsequent analysis by RT-PCR and the telomeric repeat amplification protocol assay confirmed expression of the inserted gene and induction of telomerase activity in leiomyoma and myometrial cells. Analysis of cells for estrogen receptor-alpha and progesterone receptor proteins by Western blotting showed no change in expression of these proteins between the immortalized and parental leiomyoma and myometrial cells. Both immortalized and parental myometrial and leiomyoma cells expressed the smooth muscle-specific cytoskeletal protein alpha-actin and were negative for mutant p53 protein as evidenced by immunocytochemical staining. The immortalized leiomyoma and myometrial cells showed no anchorage-independent growth, with the exception of a small subpopulation of immortalized leiomyoma cells at a higher passage that did form two to three small colonies (per 50,000 cells) in soft agar. None of the immortalized cells were tumorigenic in nude mice. In conclusion, our data show the successful insertion of the hTERT gene into leiomyoma and myometrial cells and the immortalization of these cell lines without phenotypic alteration from the parental cell types (up to 200 population doublings). These cells should help to advance research in understanding the molecular pathways involved in the conversion of a normal myometrial cell to a leiomyoma cell and the mechanisms responsible for the growth of uterine leiomyomas. Answers to these questions will undoubtedly lead to the development of more effective treatment and intervention regimens for clinical cases of uterine leiomyoma.

Expression of telomerase reverse transcriptase (TERT) in malignant mesotheliomas

To evaluate the usefulness of determinations of telomerase activity for distinguishing malignant from benign mesothelial lesions, immunohistochemical (using a rabbit polyclonal antibody and the peroxidase method; n = 68) and in situ hybridization (using sense and antisense oligonucleotide probes; n = 46) studies were made on malignant mesotheliomas (epithelioid, 39; sarcomatoid, 18, including 2 of the desmoplastic type; and biphasic, 11) and 19 benign mesothelial lesions (benign mesothelial hyperplasia, 3; and reactive pleuritis, 16). In addition, biochemical studies of telomerase activity were made in 9 of the malignant mesotheliomas. Telomerase activity was detected histochemically in all but one of the malignant mesotheliomas, but only in one (pleuritis) of the benign lesions, in which it was present only in activated lymphocytes. Antisense hybridization signals indicated the presence of telomerase mRNA mainly in the cytoplasm of the malignant cells. Sense probes gave negative results. Biochemical determinations revealed a strong telomerase activity in the 9 malignant mesotheliomas examined. This study demonstrates the usefulness of immunohistochemical staining for the evaluation of mesotheliomas. The required immunostaining can be performed using paraffin sections of formalin-fixed tissues.

Telomerase activity in sex cord-stromal tumors of the ovary

OBJECTIVE

Telomerase is a ribonucleoprotein that protects chromosomes from degradation and end-to-end fusions by maintaining telomere length. Studies have shown that telomerase is present in 95% of gynecologic malignancies and in 88% of epithelial ovarian carcinomas but undetectable in benign tissue. The aim of this investigation was to determine whether telomerase is present in sex cord-stromal tumors and whether telomerase activity is indicative of patient outcomes.

METHODS

Forty-five consecutive sex cord-stromal ovarian tumors were analyzed by using reverse transcription-polymerase chain reaction for expression of human telomerase, human telomerase reverse transcriptase, and telomerase activity.

RESULTS

Of the 29 patients with malignant cell types (granulosa cell, Sertoli-Leydig cell, and steroid cell tumors), 21 of the 28 patients (75%) available for follow-up had recurrence, with a mean follow-up of 86 months (95% CI, 36-157 months). The telomerase repeat amplification protocol assay had a sensitivity of 74% and specificity of 94% for malignancy. Patients with telomerase-positive tumors had a mean disease-free interval of 66.5 months; for those with telomerase-negative tumors the interval was 90 months. In addition, patients with telomerase-positive tumors were more likely to be dead from disease or alive with disease than those without telomerase activity, and they showed trends toward requiring a larger number of surgical procedures for the treatment of their disease. However, these trends were not statistically significant.

CONCLUSION

Although activation of telomerase is clearly an important step in carcinogenesis, it is unlikely to be helpful in the clinical management of sex cord-stromal tumors of the ovary.

Expression of human telomerase reverse transcriptase, the catalytic subunit of telomerase, is associated with the development of persistent disease in complete hydatidiform moles

OBJECTIVE

This study was undertaken to determine the putative role of telomerase activity and human telomerase reverse transcriptase (hTERT) expression in the development of persistent disease in patients with a diagnosis of complete hydatidiform mole. The ribonucleoprotein telomerase has been shown to have a major role in the process of cellular immortality and carcinogenesis. The reactivation of this enzyme that occurs in the development of malignancies appears to be limited by the regulation of its catalytic subunit hTERT. Compared with their somatic counterparts, most human malignancies demonstrate telomerase activity, and this activity is dependent on the cellular presence of hTERT. The role of telomerase in the pathogenesis of complete hydatidiform moles is not clearly understood. Moreover, the role of hTERT in trophoblastic disease, as well as in the development of persistent trophoblastic disease, has yet to be elucidated.

STUDY DESIGN

Telomerase activity and hTERT expression were analyzed in the initial uterine evacuation specimen of 54 complete hydatidiform moles by use of the telomeric repeat amplification protocol assay and reverse transcription-polymerase chain reaction methods. The results were compared and then correlated with the development of persistent trophoblastic disease.

RESULTS

Among the 54 patients who were examined with a diagnosis of complete hydatidiform mole, persistent trophoblastic disease requiring postevacuation chemotherapy developed in 6. In the remaining 48 patients, spontaneous remission of the disease occurred after uterine evacuation. Both telomerase activity and hTERT expression were detected in all 6 cases of persistent disease on the initial molar tissue sampled. Among the 48 nonpersistent moles, telomerase activity was detected in 29 (60%) and hTERT expression was demonstrated in 26 (54%). The detection of hTERT expression was significantly associated with the presence of persistent disease (P =.035). Moreover, the absence of hTERT expression in molar tissue obtained from uterine evacuation demonstrated a 100% negative predictability in determining cases of complete mole that were nonpersistent.

CONCLUSIONS

Compared with telomerase activity, the expression of hTERT is significantly associated with the development of persistent disease in complete hydatidiform moles. The absence of hTERT expression in the initial tissue sample from complete moles may have potential clinical value in determining patients who will eventually undergo spontaneous remission after uterine evacuation.

Telomerase activity in Papanicolaou smear-negative exfoliated cervical cells and its association with lesions and oncogenic human papillomaviruses

OBJECTIVE

The goal of this study was to evaluate telomerase activity in exfoliated cervical cells and its association with cytology, pathology, and human papillomavirus (HPV).

METHODS

Telomerase activity and HPV DNA sequences were examined in the exfoliated cervical cells from a general population of 245 women aged more than 30 years undergoing routine cervical screening by Papanicolaou smear. The women who were found to have telomerase activity or abnormal cytology in their exfoliated cervical cells were examined for cervical lesions by colposcopy and biopsy.

RESULTS

Cytology for our population (mean, 56 years) revealed only one abnormal smear (1/245, 0.4%), in which a cervical intraepithelial neoplasia grade I (CIN I) lesion was found. The exfoliated cervical cells used to prepare the smear were negative for telomerase and contained low-risk HPV DNA. Telomerase activity was found in 16 exfoliated cell samples (16/245, 6.5%); high-risk HPV DNA was found in 9 of these samples (9/16, 56%) and 9 of the biopsy specimens that could be evaluated from patients testing positive for telomerase revealed CIN I lesions (9/11, 82%).

CONCLUSIONS

Telomerase activity is often associated with high-risk HPV infection and it is suggested that telomerase assay can help to detect occult cervical lesions.

Correlation between morphology and telomerase activity in cells from exfoliative lung cytologic specimens

BACKGROUND

Telomerase is a ribonucleoprotein that compensates for the erosion of telomeres (chromosomal termini). Telomerase activity is detected in more than 85% of cancerous lesions and is therefore considered a novel marker of cancer. The authors compared cytologic morphology and telomerase activity at the cellular level to obtain further insight into their association.

METHODS

The authors used bronchial washing and brushing materials obtained from 18 patients with lung carcinomas (6 squamous cell, 8 adenocarcinoma, 2 large cell, 1 small cell, and 1 metastasis from colon carcinoma) and 20 patients with nonmalignant disease. An in situ telomeric repeat amplification protocol (TRAP) assay was performed, and routine Papanicolaou-stained slides using the same sample were assessed.

RESULTS

Nuclear fluorescent signals at the nuclear area, corresponding to telomerase activity, shown by the in situ TRAP assay were only detected in samples containing morphologically malignant cells. No nuclear fluorescence was seen in the keratinizing component of well-differentiated squamous cell carcinoma. Nuclear staining was not seen in metaplastic or basal hyperplastic cells. Cytoplasmic fluorescence was only found in macrophages and polymorphonuclear leukocytes.

CONCLUSIONS

Nuclear fluorescence corresponding to telomerase activity was not demonstrated in metaplastic or basal hyperplastic cells, thus indicating that detection of telomerase activity is closely associated with the presence of malignant cells, but not premalignant lesions, in lung carcinoma patients. Moreover, in some samples with cancer, cells failed to show telomerase activity, suggesting the limitation of this method for the detection of malignant cells in certain lung carcinoma patients.

Analysis of telomerase activity in ovarian cystadenomas, low-malignant-potential tumors, and invasive carcinomas

OBJECTIVE

Inappropriate telomerase expression has been reported to be associated with the development and/or progression of malignancies. Therefore, the purpose of the study was to determine and evaluate the levels of telomerase activity in normal ovary, cystadenomas, low-malignant-potential tumors, and carcinomas of the ovary.

METHODS

In the present study, telomerase activity was examined in frozen tissue specimens of normal ovary (n = 6), ovarian cystadenomas (n = 13), ovarian low-malignant-potential (LMP) tumors (n = 12), and ovarian invasive carcinomas (n = 81). Clinicopathological information including age at diagnosis, histological grade, FIGO stage, presence of distant metastasis at diagnosis, and residual disease was available for all patients with ovarian carcinomas (n = 81). Telomerase activity was assessed by the telomeric repeat amplification protocol (TRAP). Arbitrary values were assigned to processivity of telomerase activities based on the molecular weights of the telomeric repeat DNA ladders, and were graded as "negative," "moderate" (< or =99 bp), or "high" (>100 bp) activities. The specificity of telomerase activity was determined by the pretreatment of telomerase-positive control or tumor samples with RNase that led to the abolition of the activity. In addition, to determine the possibility of false negativity due to the presence of telomerase inhibitors, TRAP assay was performed on each of the telomerase-negative specimens by mixing them individually with the telomerase-positive control.

RESULTS

Telomerase activity in the progression of ovarian carcinogenesis was evaluated. In comparison with normal ovary/cystadenoma (32%), a much higher frequency of the moderate activity was observed in LMP tumors (67%) or invasive carcinomas (57%), suggesting a close association between the latter two categories. The results reflect a subpopulation of telomerase-positive LMP tumor cells with the potential to develop invasive carcinomas. None of the specimens of the benign or LMP tumors exhibited high activity. In contrast, 18% of ovarian invasive carcinomas showed high telomerase activity (P = 0.013, Fisher exact test) and further 57%, moderate activity (75% in all). A statistically significant difference was observed in the expression of telomerase activity between normal ovary/benign cystadenomas and ovarian invasive carcinomas (P = 0.001, chi(2) test).

CONCLUSIONS

The study showed a high prevalence of telomerase activity in LMP tumors or invasive carcinomas, the high levels of telomerase activity being associated exclusively with the invasive ovarian carcinomas. Therefore, the levels of processivity of telomerase activity and evidence of its statistically significant association with ovarian carcinoma suggest its role in the progression of ovarian carcinogenesis.

Telomerase activity in malignant ovarian tumors with deregulation of cell cycle regulatory proteins

Using a semiquantitative telomeric repeat amplification protocol assay, telomerase-positive frequencies and enzyme levels were measured. Out of 95% of 49 human ovarian tumors, the highest level of telomerase activity was observed in malignant tumors. Furthermore, by immunohistochemical staining of cell cycle regulatory proteins (pRB, p16, cyclin D1, cyclin E and p53) at the G1 checkpoint, we evaluated the relation between each protein alterations and the levels of telomerase activity. We could not demonstrate a clear relation with each molecule except for cyclin E, but suggesting that aberrant accumulation of these proteins was considered as a reason for telomerase deregulation, which may play an essential role in the pathway of telomerase regulation.

Telomerase activity in complete hydatidiform mole

OBJECTIVE

The purpose of this study was to evaluate the association of telomerase activity in complete hydatidiform moles with subsequent development of persistent gestational trophoblastic tumor.

STUDY DESIGN

By means of the standard telomerase repeat assay, we examined telomerase activity in 4 normal placentas, 31 complete hydatidiform moles (16 cases of uneventful regression, according to serum levels of beta-human chorionic gonadotropin, after evacuation and 15 cases in which persistent gestational trophoblastic disease developed after evacuation), 7 invasive moles, and 5 choriocarcinoma tissue samples.

RESULTS

Telomerase activity was detected in 13 of 15 (86.7%) complete hydatidiform moles in patients who eventually underwent chemotherapy for the treatment of persistent gestational trophoblastic tumors. All 9 patients with metastatic disease (International Federation of Gynecology and Obstetrics stage III) had telomerase activity in the initial molar tissue sample. In contrast, telomerase activity was evident in only 3 of 16 (12.5%) complete hydatidiform moles from patients with spontaneous remission after evacuation (P <.05). Telomerase activity was detected in all 7 invasive moles and all 5 choriocarcinoma tissue samples but was not detected in normal placentas.

CONCLUSION

The presence of telomerase activity in complete hydatidiform moles is associated with the development of persistent gestational trophoblastic tumors, such as invasive moles and choriocarcinoma.

Clinical significance of telomerase activation and telomeric restriction fragment (TRF) in cervical cancer

Telomerase activation was examined in 50 cases of cervical cancer, 27 normal cervix and five cervical cancer cell lines using the sensitive polymerase chain reaction (PCR)-based TRAP (telomeric repeat amplification protocol) assay. Telomeric restriction fragment (TRF) length of these specimens was measured by Southern hybridisation. Telomerase activation was common in cervical cancers and was detected in 46/50 cases (92%). Telomerase activity was weak in normal cervix and was detected only in 2/27 cases (7.4%). Telomerase activity was detected in all stages of cervical cancer suggesting that it is an early event in cancer progression. The clinical significance of telomerase activation was analysed in 47 squamous cell carcinoma of the cervix. High telomerase activity was more frequently detected in advanced diseases (100% in stage III and stage IV cervical cancers combined) compared with early diseases (68.6% in stage I and stage II cancers combined). The difference was statistically significant (P < 0.02). Telomerase activity was not statistically correlated with other clinical parameters examined. This is the first report of telomeric length in human cervical cancer. Both shortening and elongation of TRF length in cervical cancers was observed. Advanced cervical cancers tended to have a wider range of variation of TRF length compared with early disease and normal cervix. There was no obvious relationship between TRF length and the clinical parameters examined including clinical staging, differentiation status of tumour, human papilloma virus (HPV) infection, recurrence rate, tumour size and invasion depth. The clinical significance of TRF length appears to be limited in cervical cancers. Our results indicate that telomerase activity is closely associated with tumour cells and may be useful as a marker for detection of tumour cells in cervical biopsies.

Effect of acetic acid on telomerase activity in cervical intraepithelial neoplasia

OBJECTIVE

To evaluate whether the telomerase activity in CIN lesions can be affected by a chemical solution of acetic acid, which is required to apply to the cervix prior to colposcopy-directed biopsy.

MATERIALS AND METHODS

Thirty-five patients with histologically confirmed high-grade squamous intraepithelial lesions of the cervix entered the study. Two specimens were collected from each patient, one before and one after the cervix was swabbed with 5% acetic acid. The standard telomeric repeat assay protocol (TRAP) was used to examine telomerase activity in these fresh frozen tissue samples. Normal cervical tissues from 10 control individuals were also examined for the presence of telomerase activity. A total of 80 specimens was analyzed.

RESULTS

Telomerase activity was detectable in 27 of 35 (77.1%) fresh tissue samples, 15 of 35 (42.9%) tissue samples swabbed with 5% acetic acid, and 0 of 10 (0%) normal cervical tissue samples, respectively. Twelve samples became telomerase negative after 5% acetic acid applied. Among the 15 telomerase-positive tissue samples swabbed with 5% acetic acid, 12 had relative weak telomerase activity compared to corresponding fresh tissue samples, the other 3 remained the same. Therefore, it is concluded that telomerase activity was affected by 5% acetic acid in 24 of 27 (88.9%) samples. Telomerase activity in HeLa cell line was also inhibited by 5% acetic acid.

CONCLUSION

We reported a relative high percentage of telomerase expression in high-grade CIN lesions when compared with previous reports. If detection of telomerase activity is to become a tool for diagnosis and prognosis of cervical neoplasias, applying acetic acid prior to colposcopy-directed biopsy that is submitted for telomerase assay should be avoided in order to increase the detection rate.

Telomeres and telomerase in endocrine pathology

Telomeres representing repetitive DNA sequences of chromosome ends are necessary for maintaining chromosomal integrity. The enzyme telomerase synthesizes de novo telomeric repeats and incorporates them onto the DNA 3'-ends of chromosomes. Stability of chromosome ends and activation of telomerase are elementary requirements for cell immortalization and tumor progression. The telomeric length and telomerase activity have been recently studied in several human neoplasms, including those of endocrine tissues. Assessment of telomerase activity may help to distinguish normal or hyperplastic from neoplastic tissues. Inhibition or inactivation of telomerase activity may provide novel strategies for cancer therapy.

Telomerase activation in in vitro and in vivo cervical carcinogenesis

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 (chi2 = 7.42, P < 0.01) and was much higher in invasive carcinomas than in CINs (chi2 = 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.

A survey of telomerase activity in human cancer

Research on the association of the ribonucleoprotein enzyme, telomerase, with human cancer has expanded rapidly in recent years. Essentially all major types of cancer have been screened and the presence of telomerase activity has been detected in the vast majority of cases. In this article we provide a summary, in table form, of the current data.