Telomerase as a prognostic marker in breast cancer: high-throughput tissue microarray analysis of hTERT and hTR

Analysis of hTERT mRNA expression in biliary tract and pancreatic cancer

BACKGROUND/PURPOSE

Telomerase, an enzyme that prevents the loss of telomere regions consisting of TTAGGG repeats, which maintain the stability of cells, is considered to be involved in cell immortality and cancer growth. Recent genetic analysis has shown that the mRNA for the catalytic subunit of human telomerase reverse transcriptase (hTERT) is expressed in many cancer tissues.

METHODS

In this study, we measured hTERT mRNA levels in bile samples from patients with pancreatobiliary disease, and we combined the hTERT mRNA analysis with conventional cytology to achieve an accurate preoperative diagnosis. Bile samples were obtained from 19 patients with biliary tract cancer, 6 with gallbladder cancer, 10 with pancreatic cancer, 1 with gastric cancer, and 10 with benign disease. These samples were examined cytologically, and analyzed for hTERT mRNA levels.

RESULTS

The Combination of cytological examination and hTERT mRNA analysis achieved a positive rate of 78.9% in diagnosing biliary tract cancer, significantly improving the diagnostic accuracy over that for either method alone (P = 0.01). The diagnostic sensitivity for malignant disease was 66.6%, also significantly improving the diagnostic accuracy compared with either method alone (P = 0.001).

CONCLUSIONS

The combination of cytological examination and hTERT mRNA analysis appeared useful for the preoperative diagnosis of malignant biliary tract diseases, but was not superior to diagnostic imaging studies, and therefore remains an adjunct to cytological examination. Further studies should lead to improvements in the combination's diagnostic capabilities.

Mechanism of telomerase activation by v-Rel and its contribution to transformation

Telomerase is activated during the transformation of lymphoid cells and fibroblasts by v-Rel, the oncogenic member of the Rel/NF-kappaB family of transcription factors. v-Rel-transformed cell lines have longer telomeres than untransformed chicken lymphoid cells and have high levels of telomerase activity. v-Rel-mediated activation of telomerase is achieved by multiple mechanisms. The expression of the gene encoding the catalytic subunit of telomerase (TERT) was directly upregulated by v-Rel. Moreover, the expression of v-Rel altered the ratio of alternatively spliced and full-length TERT transcripts in favor of the full-length forms. The activation of telomerase by v-Rel in lymphocytes was also accompanied by inactivation of nuclear inhibitors. The inhibition of telomerase activity in v-Rel-transformed cell lines led to apoptosis within 24 h. The expression of v-Rel in a macrophage cell line resulted in elevated levels of reactive oxygen species (ROS), increased telomerase activity, and increased sensitivity to telomerase inhibitors. In contrast, the ectopic expression of TERT decreased the extent of apoptosis induced by ROS. The activation of telomerase by v-Rel may, therefore, partially protect the transformed cells from apoptosis induced by ROS.

Real-time telomerase activity measurements for detection of cancer

Since the hallmark report of the PCR-based telomeric repeat amplification protocol (TRAP) in 1994, there has been a flurry of investigations of telomerase activity on normal, benign, premalignant and cancerous samples representative of the various stages of tumorigenesis. Basic research and technological advances in human genetics, biochemistry and model systems have brought much progress towards the understanding of human infectious, hereditary and somatically acquired diseases. The knowledge of carcinogenesis has increased very rapidly in the past few years, particularly with the development of automated molecular biologic analysis of tumors and preneoplastic lesions. Despite the wide variety of studies on the potential use of telomerase as a cancer biomarker, the variability of reported telomerase activity and the lack of a transferable detection method have prevented it from becoming a routine clinical application. Real-time PCR is a clinically transferable method and the advancement of real-time measurements of telomerase will facilitate moving telomerase activity and technologies towards clinical validation. It is expected that the next 5 years will see telomerase integrated into the initial detection and follow-up monitoring of cancer patients. The hope is that the use of telomerase will finally translate into a diagnostic to help realize longer survival and a better quality of life.

Protein Expression Profiling in High-Risk Breast Cancer Patients Treated with High-Dose or Conventional Dose–Dense Chemotherapy

PURPOSE

To characterize the prognostic and predictive impact of protein expression profiles in high-risk breast cancer patients who had previously been shown to benefit from high-dose chemotherapy (HDCT) in comparison to dose-dense chemotherapy (DDCT).

EXPERIMENTAL DESIGN

The expression of 34 protein markers was evaluated using tissue microarrays containing paraffin-embedded breast cancer samples from 236 patients who were randomized to the West German Study Group AM01 trial.

RESULTS

(a) 24 protein markers of the initial panel of 34 markers were sufficient to identify five profile clusters (subtypes) by K-means clustering: luminal-A (27%), luminal-B (12%), HER-2 (21%), basal-like (13%) cluster, and a so-called "multiple marker negative" (MMN) cluster (27%) characterized by the absence of specifying markers. (b) After DDCT, HER-2 and basal-like groups had significantly worse event-free survival [EFS; hazard ratio (HR), 3.6 [95% confidence interval (95% CI), 1.65-8.18; P = 0.001] and HR, 3.7 (95% CI, 1.68-8.48; P < 0.0001), respectively] when compared with both luminal groups. (c) After HDCT, the HR was 1.5 (95% CI, 0.76-3.05) for EFS in the HER-2 subgroup and 1.1 (95% CI, 0.37-3.32) in the basal-like subgroup, which indicates a better outcome for patients in the HER-2 and basal-like subgroups who received HDCT. The MMN cluster showed a trend to a better EFS after HDCT compared with DDCT.

CONCLUSIONS

Protein expression profiling in high-risk breast cancers identified five subtypes, which differed with respect to survival and response to chemotherapy: In contrast to luminal-A and luminal-B subtypes, HER-2 and basal-like subgroups had a significant predictive benefit, and the MMN cluster had a trend to a predictive benefit, both from HDCT when compared with DDCT.

Immunohistochemical properties of ocular adenomas, adenocarcinomas and medulloepitheliomas

Ocular medulloepitheliomas, adenomas and adenocarcinomas share a common phenotype and originate from the optic cup neuroectoderm. This can make it very difficult to differentiate between these tumors histopathologically. Therefore, this study focused on identifying a combination of immunologic markers that might be used in the diagnosis of these tumors. These markers included AE1/AE3, CK7, CK20, and telomerase reverse transcriptase (TERT). Routine immunohistochemical staining was performed on 27 whole globes diagnosed with one of these tumors. The tumors that immunostained for TERT showed increasing immunoreactivity as the tumor types increased in aggressiveness. None of the tumor types were immunopositive for CK7. CK20 immunostaining was found in the adenomas but not in the adenocarcinomas or medulloepitheliomas. AE1/AE3 expression was present more consistently in the adenocarcinomas and less frequently in the adenomas. AE1/AE3 expression was present in only one of six medulloepitheliomas. Furthermore, CK20 and TERT showed inverse expression patterns, i.e. TERT increased in expression and CK20 decreased in expression with increasing aggressiveness. These results may be important diagnostic and prognostic indicators for these tumors.

DNA flow cytometry but not telomerase activity as predictor of disease-free survival in pT1-2/N0/G2 breast cancer

OBJECTIVE

In the subgroup of patients with node-negative (N0) moderately differentiated (G2) breast cancer, the clinical decision of giving adjuvant therapy is critical. The aim of this study was to investigate the prognostic value of biomarkers (DNA flow cytometry and telomerase activity in correlation with routinely used estrogen receptors (ER) and HER oncoprotein) in pT1-2/N0/G2 breast cancer, for improving therapeutic management.

METHODS

The series involved 135 patients with pT1-2/N0/G2 breast cancer and median follow-up of 58.5 months. DNA ploidy and S-phase fraction (SPF) (<or=5%; 5-10%; >10%) were assessed on frozen samples. Telomerase activity, ER and c-erbB-2 expression were analyzed by standardized immunohistochemistry techniques. A Cox regression analysis was performed for prognostic evaluation.

RESULTS

Aneuploidy significantly correlated with high SPF and lack of ER, while high SPF showed significant correlations with high telomerase activity, c-erbB-2 overexpression and absence of ER. Kaplan-Meier curves showed significant differences for ploidy and SPF in relation with disease-free survival (DFS) and overall survival (OS), and a statistical trend for ER. By Cox regression analysis, DNA aneuploidy (RR = 16.7; p = 0.007) and high SPF (RR = 23.1; p = 0.004) revealed significant correlations with worse DFS. Among patients with diploid (n = 76) and low/intermediate SPF (n = 85) tumors, only one had recurrence of the disease. No association between telomerase activity and clinical outcome was observed.

CONCLUSION

In pT1-2/N0/G2 breast cancer patients, DNA ploidy and SPF are relevant prognostic biomarkers that should be considered as additional tools in the therapeutic planning.

Dyskerin expression influences the level of ribosomal RNA pseudo-uridylation and telomerase RNA component in human breast cancer

Dyskerin is a nucleolar protein, altered in dyskeratosis congenita, which carries out two separate functions, both fundamental for proliferating cells. One function is the pseudo-uridylation of ribosomal RNA (rRNA) molecules, necessary for their processing, and the other is the stabilization of the telomerase RNA component, necessary for telomerase activity. A significant feature of dyskeratosis congenita is an increased susceptibility to cancer; so far, however, no data have been reported on dyskerin changes in human tumours. Therefore, in this study, the distribution of dyskerin in a large series of human tumours from the lung, breast, and colon, as well as from B-cell lymphomas, was analysed by immunohistochemistry. Dyskerin proved never to be lost or delocalized outside the nucleolus. A quantitative analysis of dyskerin mRNA expression was then performed in 70 breast carcinomas together with the evaluation of telomerase RNA component levels and rRNA pseudo-uridylation. Dyskerin mRNA levels were highly variable and directly associated with both telomerase RNA component levels and rRNA pseudo-uridylation. Dyskerin gene silencing in the MCF-7 human breast carcinoma cell line reduced telomerase activity and rRNA pseudo-uridylation. Significantly, patients with low dyskerin expression were characterized by a better clinical outcome than those with a high dyskerin level. These data indicate that dyskerin is not lost in human cancers and that the levels of its expression and function are associated with tumour progression.

Telomerase template antagonist GRN163L disrupts telomere maintenance, tumor growth, and metastasis of breast cancer

PURPOSE

Maintenance of telomeres by telomerase is critical for the continuing proliferation of most advanced cancer cells. Telomerase activity has been detected in the vast majority of cancer cells but not most normal cells, making the enzyme an attractive target for anticancer therapy. The aim of this study was to address the breast cancer translational potential of the novel telomerase inhibitor, GRN163L.

EXPERIMENTAL DESIGN

In the present study, we investigated the effects of GRN163L treatment on a panel of breast cancer cells representing different tumor subtypes with varying genetic backgrounds, including ER+, ER-, HER2+, BRCA1 mutant breast tumor cells as well as doxorubicin-resistant cancer cells. To investigate the in vivo effects of GRN163L, we employed a breast cancer xenograft and metastasis model that simulates a clinical situation in which a patient arrives with a primary tumor that may be then treated or surgically removed.

RESULTS

GRN163L effectively inhibited telomerase activity in a dose-dependent fashion in all breast cancer cell lines resulting in progressive telomere shortening. A mismatch control oligonucleotide showed no effect on telomerase activity and GRN163L did not significantly affect telomere shortening in normal human mammary epithelial cells or in endothelial cells. Breast cancer cells that exhibited telomerase inhibition also exhibited significant reduction in colony formation and tumorigenicity. Furthermore, GRN163L suppressed tumor growth and lung metastases (P = 0.017) of MDA-MB-231 cells in vivo after 4 weeks of treatment.

CONCLUSIONS

These results show in vivo effectiveness of GRN163L in breast cancer and support its promising clinical potential for breast cancer treatment.

Missing association between telomerase activity and clinicopathological features in patients with early stage carcinoma of the cervix

OBJECTIVES

This study was undertaken to evaluate the association between the telomerase activity in the tumor and clinicopathological findings in patients with stage IB-IIA (FIGO) carcinoma of the cervix.

METHODS

Thirty-eight patients with carcinoma of the cervix submitted to radical hysterectomy were prospectively from January 1998 to November 2001. Samples from the tumor were taken and analyzed by the telomerase PCR-TRAP-ELISA kit. Clinicopathological characteristics such as age, stage, tumor size, grade of differentiation, lymphatic vascular space invasion (LVSI), parametrial involvement and status of pelvic lymph nodes were also recorded.

RESULTS

Patient's mean age was 49.3+/-1.99 years (29-76 years). The clinical stage (FIGO) was IB in 35 patients (92.1%) and IIA in 3 patients (7.9%). The histological classification identified squamous cell carcinoma in 33 patients (86.8%) and adenocarcinoma in 5 patients (13.2%). There was no association between age, clinical stage, histological classification, tumor size, grade of differentiation and presence of LVSI with tumoral telomerase activity. The telomerase activity was not associated with the presence of vaginal involvement (P=0.349), parametrium involvement (P=0.916), pelvic lymph node metastasis (P=0.988) or tumoral recurrence (P=0.328) in patients with carcinoma of the cervix.

CONCLUSIONS

Telomerase activity in the tumor is not associated with clinicopathological findings or tumor recurrence in patients with early stage cervical carcinoma.

Dendritic cell immunotherapy for breast cancer

Novel adjuvant therapies are urgently needed to complement the existing treatment options for breast cancer. The advent of the use of dendritic cells (DCs) for cancer immunotherapy provides a unique opportunity to overcome the relative non-immunogenic property of breast tumours and address the underlying immunodeficiency. To date, the success of this approach has been limited, possibly due to the targeting of specific tumour antigens that rapidly mutate and, thus, become undetectable to the immune system. A more efficient approach would include preparations encompassing multiple antigens, such as those provided by loading of whole tumour cells or tumour RNA. It is proposed that targeting mammary stem cells responsible for resistance to chemo/immunotherapy, through the expression of a broad array of wild-type and mutated tumour antigens in the context of DCs, will become a mainstay for immunotherapy of breast cancer.

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.

Tissue microarrays: bridging the gap between research and the clinic

Tissue microarrays are a high-throughput method for the investigation of biomarkers in multiple tissue specimens at once. This technique allows for the analysis of up to 500 tissue samples in a single experiment using immunohistochemistry and in situ hybridization. Recently, cell lines and xenografts have been reduced to a tissue microarray format and are being applied to preclinical drug development. In clinical research, tissue microarrays are applied at multiple levels: comprehensive analysis of samples in the context of a clinical trial or across a population. Tissue microarrays play a central role in translational research, facilitating the discovery of molecules that have potential roles in the diagnosis, prognosis and prediction of response to therapy.

Proteomics of breast cancer: principles and potential clinical applications

Progresses in screening, early diagnosis, prediction of aggressiveness and of therapeutic response or toxicity, and identification of new targets for therapeutic will improve survival of breast cancer. These progresses will likely be accelerated by the new proteomic techniques. In this review, we describe the different techniques currently applied to clinical samples of breast cancer and the most important results obtained with the two most popular proteomic approaches in translational research (tissue microarrays and SELDI-TOF).

Cytoplasmic overexpression of ALCAM is prognostic of disease progression in breast cancer

BACKGROUND

Activated leucocyte cell adhesion molecule (ALCAM, CD166) is a cell surface member of the immunoglobulin superfamily. ALCAM expression has prognostic relevance in prostate and colon cancer.

OBJECTIVE

To evaluate ALCAM protein expression in breast cancer by immunohistochemistry and to correlate expression levels with clinicopathological data.

METHODS

162 primary breast carcinomas with a mean clinical follow up time of 53 months were immunostained using a monoclonal ALCAM antibody. The staining was evaluated as an immunoreactive score (IRS) and grouped into low v high for both membranous and cytoplasmic staining.

RESULTS

Intraductal and invasive carcinomas showed a higher ALCAM expression (median IRS 4 and 6 respectively) than normal breast tissue (IRS 2). In univariate survival analyses a significant association of high cytoplasmic ALCAM expression with shortened patient disease-free survival (mean (SD) five year non-progression rate, 69.4 (4.6)% v 49.4 (11.1)%, p = 0.0142) was found. In multivariate analyses of disease-free survival times, high cytoplasmic ALCAM expression (relative risk (RR) = 2.086, p = 0.026) and nodal status (RR = 2.246, p = 0.035) were significantly associated with earlier disease progression, whereas tumour grading (RR = 1.6, p = 0.052) was of borderline significance.

CONCLUSIONS

The data suggest that strong cytoplasmic ALCAM expression in primary breast cancer, as detected by immunohistochemistry, might be a new marker for a more aggressive breast cancer biology.

High Telomerase RNA Expression Level Is an Adverse Prognostic Factor for Favorable-Histology Wilms' Tumor

Purpose

A primary objective of the fifth National Wilms Tumor Study (NWTS-5) was to identify prognostic indicators for patients with favorable-histology Wilms' tumor. The prognostic significance of telomerase expression level in primary tumor samples was assessed.

Patients and Methods

A case-cohort study was conducted involving 291 NWTS-5 registrants. Telomerase activity was measured using the telomeric repeat amplification protocol (TRAP). Expression levels of TERT mRNA (encoding the telomerase catalytic component) and TERC/hTR (the telomerase RNA template) were measured using quantitative real-time polymerase chain reaction.

Results

After excluding samples because of lack of viable tumor, RNA degradation, or insufficient clinical information, 244 patients remained for the final analysis (96 with relapse and 148 without relapse). Univariate analysis revealed a positive correlation between relative risk (RR) of relapse and levels of TERT mRNA and TERC expression. For each doubling in TERT mRNA and TERC level, the RR increased by a factor of 1.16 (95% CI, 1.04 to 1.29; P = .01) and 1.35 (95% CI, 1.11 to 1.64; P = .003), respectively. The one third of patients whose tumors had the highest TERC expression level had an RR of 2.06 (95% CI, 1.14 to 3.70; P = .02) compared with patients with the lowest level. TERC expression level remained a significant prognostic indicator in a multivariate analysis adjusting for TERT mRNA, tumor stage, and patient age. TRAP level did not correlate with RR of relapse. Telomerase expression levels were not predictive of overall survival.

Conclusion

Telomerase RNA expression level may provide a clinically useful adjunct to the current risk classification schema for favorable-histology Wilms' tumor.

Activation of telomerase and expression of human telomerase reverse transcriptase in coronary atherosclerosis

INTRODUCTION

Considerable research on telomerase on human neoplastic and normal long-lived proliferative tissues has emerged. We explored the expression of telomerase in atherosclerotic human epicardial coronary arteries.

METHODS

Forty discrete human coronary arterial segments obtained from 19 heart transplant recipients were classified into nonatherosclerotic and atherosclerotic groups based on coronary angiography and histological examination. PCR-ELISA-based telomeric repeat amplification protocol (TRAP), and immunohistochemical analyses were conducted to determine the functional activity and cell-specific expression of telomerase.

RESULTS

Seventy percent of atherosclerotic coronary arteries exhibited positive telomerase activity, and the reactivation incidence reached fourfold higher than that of controls (P=.007). The telomerase catalytic protein, human telomerase reverse transcriptase (hTERT), was expressed in 88% of atherosclerotic tissues, a fivefold higher frequency compared with that of the controls. There was also a correlation of hTERT expression with the level of telomerase bioactivity (P=.017) and with the severity of atherosclerotic grade (P<.001). In comparison with the immunostaining of mitotic antigen, Ki-67, we found an association of hTERT expression with actively cycling cells in early lesions but with quiescent cells in late advanced atherosclerotic stages.

CONCLUSIONS

The up-regulation of telomerase and its catalytic hTERT protein during stages of atherosclerotic evolution may implicate a role of telomerase in vascular remodeling underlying atherogenesis.

The tea polyphenols EGCG and EGC repress mRNA expression of human telomerase reverse transcriptase (hTERT) in carcinoma cells

Tea polyphenols have inhibitive effects for carcinogenesis. A reporter system controlled by hTERT promoter was constructed to evaluate the effects of tea polyphenols, (-)-epigallocatechin-3-gallate (EGCG) and (-)-epigallocatechin (EGC) on the repression of hTERT transcription. The hTERT promoter activity was selectively repressed by 20-40 microM EGCG and EGC in a dose- and time-dependent manner. Real-time RT-PCR confirmed that the endogenous hTERT mRNA level was decreased in H1299, OECM-1 and SAS cells treated with EGCG or EGC. Our results identified the repression activities of EGCG and EGC toward telomerase expression that might be linked to inhibition of carcinoma cell growth. This cell-based reporter system is useful for screening drugs targeting hTERT repression.

Telomerase activity in urine sediments as a tool for noninvasive detection of bladder cancer

Telomerase is extensively investigated as potential diagnostic and prognostic marker in human tumors. In this study, we determined telomerase activity in histological specimens and voided urine of 52 human bladder cancers. Using the PCR-ELISA method telomerase activity was found in 21 (88%) of the 24 tumor tissues and in the corresponding sediments from voided urine of patients with superficial bladder carcinoma (Ta/T1). In case of muscle-invasive tumors (T2-T4), telomerase activity was found in 27 (96%) of the 28 tumor tissues and in 26 (93%) of the 28 urine sediments. Enzyme activity was not detected in 13 control urine sediments. Telomerase activity was not significantly associated with clinicopathological parameters supporting the diagnostic rather than prognostic value of this marker in bladder cancer. The present study demonstrates that telomerase activity detection in voided urine has high potential for noninvasive diagnosis of superficial bladder tumors.

Correlation of CHEK2 protein expression and c.1100delC mutation status with tumor characteristics among unselected breast cancer patients

The CHEK2 kinase is a tumor suppressor whose activation in response to DNA double-strand breaks contributes to cell cycle arrest or apoptosis. The c.1100delC mutation is associated with familial breast cancer, and tumors from mutation carriers show reduced or absent CHEK2 protein expression. We have here studied CHEK2 protein expression by immunohistochemistry on a tissue microarray of 611 unselected breast tumors and also evaluated the tumor characteristics among 1,297 unselected breast cancer patients defined for the c.1100delC germ line mutation status (2.5% carrier frequency). CHEK2 protein expression was reduced in 21.1% of the unselected breast cancers studied. Tumors with reduced CHEK2 expression had more often larger primary tumor size (pT3-4; nominal significance p = 0.002) compared to tumors with normal staining. A similar trend for larger tumor size was seen among the 37 breast tumors from c.1100delC germ line mutation carriers. Tumors from c.1100delC mutation carriers were of higher grade than those of noncarriers (nominal significance p = 0.02). The c.1100delC germ line mutation also associated strongly with bilateral breast cancer. No significant correlation was seen between CHEK2 status and hormone receptor status, histology, lymph node status, or overall survival.

Telomerase as an independent prognostic factor in head and neck squamous cell carcinoma

BACKGROUND

Telomerase activity has been found to be associated with many cancers, including head and neck squamous cell carcinoma (HNSCC). We examined the association of telomerase activity with the clinical outcome of patients with HNSCC.

METHODS

A PCR-based enzyme immunoassay method was used to measure telomerase activity in 217 matched (grossly normal and cancerous) tissues from patients with HNSCC. Pearson chi-square test was used to analyze the correlation of telomerase activity with clinicopathologic parameters. Kaplan-Meier method and Cox logistic regression model were used for prognostic analysis.

RESULTS

Of the 217 tissues assayed, 4.1% of the normal and 63.3% of the cancer tissues had high levels of telomerase activity. Telomerase activity was shown to be statistically correlated with extracapsule spreading (ECS) of lymph nodes (p =.005) and overall survival (p =.003). On multivariant analysis, overall stage (p =.007), tumor depth (p =.045), and telomerase activity (p =.008) showed independent variables associated with poor survival.

CONCLUSIONS

Telomerase activity has been shown to be an independent prognostic factor for survival in cases of HNSCC. Telomerase may be a potential molecular target for clinical use in prognostication and therapy in cases of the disease.

Telomerase in breast cancer: a critical evaluation

Human chromosomes have highly specialized structures at their ends termed telomeres, repetitive, non-coding DNA sequences (5'-TTAGGG-3'), ranging in size from 5 to 20 kb in human cells. These highly specialized structures prevent chromosome ends from being recognized as double-strand DNA breaks, and they also provide protection from destabilizing agents. The mechanism for maintaining telomere integrity is controlled by telomerase, a ribonucleoprotein enzyme that specifically restores telomere sequences lost during replication by using an intrinsic RNA component as a template for polymerization. Telomerase has two core functional components required for its activity: the catalytic subunit of human telomerase reverse transcriptase (hTERT) and a telomerase RNA template (hTR). Telomerase is activated in the majority of immortal cell lines in culture and in most malignant tumors. This review outlines our current understanding of telomerase in breast cancer development and critically evaluates potential utilities in diagnosis, prognosis, and therapy.

Tissue microarrays

The identification of disease-related genes is a major focus of modern biomedical research. Recent techniques, including array-based platforms for molecular profiling of disease tissues such as DNA arrays for expression profiling or matrix comparative genomic hybridization, allow for the comprehensive screening of the whole genome in a single experiment. Consequently, thousands of candidate genes have already been identified that may be linked to disease development and progression, and the process of lead discovery continues unimpeded. The evaluation of the clinical value of such leads is challenging because thousands of well-characterized tissue specimens must be analyzed. Tissue microarray (TMA) technology enables high-throughput tissue analyses to keep pace with the rapid process of lead discovery. With this technique, up to 1000 minute tissue samples are brought into an array format and analyzed simultaneously. The TMA technology is a fast, cost-effective, and statistically powerful method that will substantially facilitate translational research.

Telomere maintenance in clinical medicine

Telomeres, the ends of linear chromosomes, shorten with each round of DNA replication. Loss of telomeric DNA can lead to senescence, a state in which cells no longer divide, and crisis, which triggers cell death. To prevent these phenomena, cancer and stem cells must maintain their telomeres, for example, by expressing telomerase, an enzyme that can extend telomeres. As our knowledge of telomere maintenance increases, opportunities arise for translating telomere biology into clinical medicine. Areas of current investigation include the development of diagnostic and prognostic markers for cancer; the development of chemotherapeutic agents based on telomerase inhibition, an immune response to telomerase, or telomerase-based gene therapy; and engineering rejuvenated tissues by restoring telomerase expression.

Validation of tissue microarray technology in ovarian carcinoma

High-throughput tissue microarray allows many clinical specimens to be analyzed simultaneously on a single slide. One potential limitation of tissue microarray is the correct representation of each tumor with the small tissue core. Because tumors from different organs have different levels of heterogeneity, it requires a validation study for each one of them. We compared immunostaining of Ki-67, estrogen receptors, and p53 in whole sections of 45 cases of high-grade serous ovarian carcinoma with six core samples from those sections with regard to the number of tissue cores needed to reliably represent a whole section. Staining for Ki-67 was graded high or low by automated image analysis of 10 high-power fields; staining for estrogen receptor and p53 was scored on a 0-to-3 scale. Correlation coefficients for whole-section vs core stains were 0.86 for Ki-67, 0.93 for estrogen receptors, and 0.82 for p53. A total of 54 (6.6%) of the cores were inadequate for scoring. The probability that results from one core would correctly represent all three markers in the whole section was 91%; that for two cores was 96%; and that for three cores was 98%. Our results show that analysis of a single readable core matched the staining pattern of a whole section more than 90% of the time, and analysis of two cores increased that value to more than 95%, demonstrating that ovarian carcinoma tissue microarray is a reliable technique to analyze the expression of markers.

Telomerase, telomerase inhibition, and cancer

Telomeres, located at the ends of eukaryotic chromosomes, are synthesized by the enzyme telomerase and are responsible for maintaining chromosome length. The absence of telomerase in most somatic cells has been associated with telomere shortening and aging of these cells. In contrast, high levels of telomerase activity are observed in over 90% of human cancer cells. The absence of telomerase in normal and aging cells is considered a natural defense against development of cancer. However, we do not know what triggers the reappearance of telomerase in cancer cells. Telomerase activity is directly correlated with the expression of its active catalytic component, the human telomerase reverse transcriptase (hTERT), which is believed to be controlled primarily at the level of transcription. Elucidation of the control of telomerase in aging and in cancer as an age-related disease has considerable potential in leading to novel approaches in anti-aging medicine.

Biomolecular prognostic factors in breast cancer

PURPOSE OF REVIEW

To update clinicians on recent findings concerning the clinical usefulness of biomarkers in breast cancer, this review examines recently published papers dealing with promising prognostic/predictive biological factors. These factors can be classified according to their involvement in the main alterations characterizing tumor cells: self-sufficiency in growth signals, insensitivity to anti-growth signals, evasion of apoptosis, limitless replicative potential, sustained angiogenesis, and tissue invasion and metastasis.

RECENT FINDINGS

Despite relevant research efforts and the identification of many putative good prognosticators, few of these factors are proving clinically useful for identifying patients at minimal risk of relapse, patients with a worse prognosis, or patients likely to benefit from specific treatments. Most of them, such as HER-2/neu, epidermal growth factor receptor, cyclin E, p53, bcl-2, vascular endothelial growth factor, urokinase-type plasminogen activator-1 and the recently discovered anti-apoptosis protein survivin, are suggested for possible inclusion in the category of biomarkers with a high level of clinico-laboratory effectiveness. However, no single biomarker was able to identify those patients with the best (or worst) prognosis or those which would be responsive to a given therapy. Novel findings derived from gene-expression analysis indicate that the simultaneous consideration of molecular alterations contributing to the hallmarks of cancer might provide clinically useful prognostic, and perhaps therapeutic, information.

SUMMARY

Rapid translation of laboratory findings to clinical practice was hampered by many difficulties, including technical and statistical concerns, a lack of assay standardization and comparability, and the modest design of translational studies. Many studies are performed on too small series of patients to provide reliable results; the studies are often heterogeneous in terms of treatment, patients and tumor characteristics, and data may be evaluated using different analytical approaches and are thus not easily comparable. Adequately planned prospective studies are required to assess the clinical utility of biomarker determinations.

Tissue microarrays for high-throughput molecular pathology

Modern research technologies, including DNA, protein, and antibody microarrays identify a steadily growing number of clues that are useful in molecular disease classification, drug development, and the prediction of response to treatment. Subsequent validation of the clinical importance of such candidate genes or proteins requires large-scale analysis of human tissues. To date, this analysis constitutes an important bottleneck in the process of discovery because tissue analysis by the conventional slide-by-slide strategy is slow and expensive. To overcome these limitations, tissue microarray (TMA) technology has been developed. TMA allows for the simultaneous analysis of up to 1,000 tissue samples in a single experiment, using all types of in-situ analyses including immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and RNA in situ hybridization (RNA-ISH). TMA technology has the potential to greatly facilitate the translation of basic research into clinical practice. Potential applications include the establishment of associations between molecular changes and clinical endpoints, testing of potential therapeutic targets using tissue samples from specific cancer patients, standardization of molecular detection of targets, and rapid translation of results from cell lines and animal models to human cancer. Because of its beneficial economic aspects and ability to differentiate ethnic differences in tumor biology, TMA applications may become particularly important in developing countries.

Activated platelets rapidly up-regulate CD40L expression and can effectively mature and activate autologous ex vivo differentiated DC

Background DC are a promising immunotherapeutic for treatment of infectious/malignant disease. For clinical trials, immature DC generated from precursor cells such as monocytes, using serum-free media containing GM-CSF and IL-4, can be matured with specific cytokines/factors. CD40 ligand (CD40L) plays an important role in DC activation/maturation but is not available for clinical applications. These studies evaluated the feasibility of using activated platelets with elevated CD40L surface expression to stimulate autologous DC maturation. Methods Pilot and clinical scale studies were executed using magnetic/centrifugal separation. Monocyte precursors were differentiated to immature DC with GM-CSF and IL-4 and the ability of activated autologous platelets to mature these cells was evaluated on the basis of phenotype and function. Results In small-scale studies, DC cultures stimulated with activated autologous platelets (CD40L-AP), tumor necrosis factor-alpha (TNF-alpha) or soluble CD40L (sCD40L) up-regulated expression of phenotype markers indicative of activation and maturation. CD86 expression was significantly enhanced (P<0.05) by stimulation with either CD40L-AP (75.5+/-14.5%) or sCD40L (80.5%+/-5.3%) compared with immature DC (55.2+/-14.8%), as were CD80 and CD83. Similarly, in large-scale studies using Isolex 300I to enrich for monocytes and platelets for DC generation/maturation on a clinical scale, stimulation with CD40L-AP increased CD86 and CD80 expression as well as the ability to stimulate allogeneic lymphocytes compared with control cultures. Discussion These results demonstrate that thrombin-activated platelets express CD40L and are effective at inducing matured DC with potent immunogenic activity. Furthermore, these studies demonstrate the feasibility of this approach for clinical immunotherapeutic interventions.

Breast cancer in young women (?35 years): Genomic aberrations detected by comparative genomic hybridization

Sporadic breast cancer in young women is different from the one in older patients regarding pathological features and aggressiveness of the tumors, but the spectrum of genetic alterations are largely unknown. We used comparative genomic hybridization (CGH) to analyze DNA copy number changes in 88 tumor samples from women </=35 years of age. Findings were compared to histopathological data including tumor type, grading, lymph nodes and metastasis. Genomic gains clustered to chromosome arms 1q (64.8%), 8q (61.4%), 17q (50.0%), 20q (33.0%), 3q (20.5%), 1p (17.0%), 5p (17.0%) and 15q (17%). Losses were commonly located on 8p (19.3 %), 11q (11.4%), 16q (11.4%), 17p (11.4%) and 18q (10.2%). A comparison with published CGH data from breast carcinomas of similar type and grade showed the following differences: (1) gains were much more frequent than losses, and (2) losses on 8p22-p23 were more prevalent in patients with positive lymph node metastasis (p = 0.02), and Grade III tumors were associated with gains on the long arm of chromosome 8 (p = 0.01). Therefore, alterations in these genomic regions may be responsible for the reduced survival of patients with early onset breast cancer.

Tissue microarrays in cancer diagnosis

New molecular techniques such as cDNA, protein or antibody arrays allow for high-throughput identification of thousands of potentially disease-related markers on the genome, transcriptome and proteome level. Major disadvantages of such studies are the enormous costs and the need for unfixed tissues, disallowing comprehensive large-scale studies. Consequently, validation studies including large sets of clinically well-defined tissue samples are now necessary to identify those genes or proteins with true impact on the course of disease which will eventually lead to therapeutic applications. Tissue microarray technology overcomes the bottleneck of traditional tissue analysis and allows it to catch up with the rapid advances in lead discovery. Current applications and the future potential of tissue microarray technology in cancer research and diagnosis are discussed.

Detection of telomerase expression in mediastinal lymph nodes of patients with lung cancer

Mediastinal lymph nodes are the most common site of tumor spread in non-small cell lung cancer (NSCLC). We hypothesized that micrometastatic disease could be detected by reverse transcription-polymerase chain reaction (RT-PCR) for expression of human telomerase reverse transcriptase (hTERT) in mediastinal lymph nodes and that a minimally invasive technique (endoscopic ultrasound-guided fine-needle aspiration [EUS-FNA]) is capable of sampling lymph nodes for PCR analysis without surgery. Mediastinal lymph nodes were sampled with EUS-FNA in patients with NSCLC and negative control subjects undergoing EUS for benign disease. Total RNA was harvested from samples, and RT-PCR was performed to detect telomerase gene expression. RNA was available from 87 of 100 lymph node aspirates from 39 patients with NSCLC and from 12 negative control patients. hTERT was expressed in 0 of 14 negative control lymph nodes in 18 of 57 pathologically negative lymph nodes from cancer patients and in 10 of 16 pathologically positive lymph nodes (p < 0.05). Five of 18 (28%) patients with no pathologically evident mediastinal disease expressed telomerase in at least one lymph node. Minimally invasive EUS-FNA with RT-PCR is capable of detecting expression of cancer specific mRNA in lymph nodes. Approximately one-third of pathologically negative mediastinal lymph nodes in NSCLC patients express hTERT mRNA. The clinical significance of this observation is yet to be determined.

Genomics and proteomics in cancer

Cancer development is driven by the accumulation of DNA changes in the approximately 40000 chromosomal genes. In solid tumours, chromosomal numerical/structural aberrations are common. DNA repair defects may lead to genome-wide genetic instability, which can drive further cancer progression. The genes code the actual players in the cellular processes, the 100000-10 million proteins, which in (pre)malignant cells can also be altered in a variety of ways. Over the past decade, our knowledge of the human genome and Genomics (the study of the human genome) in (pre)malignancies has increased enormously and Proteomics (the analysis of the protein complement of the genome) has taken off as well. Both will play an increasingly important role. In this article, a short description of the essential molecular biological cell processes is given. Important genomic and proteomic research methods are described and illustrated. Applications are still limited, but the evidence so far is exciting. Will genomics replace classical diagnostic or prognostic procedures? In breast cancers, the gene expression array is stronger than classical criteria, but in endometrial hyperplasia, quantitative morphological features are more cost-effective than genetic testing. It is still too early to make strong statements, the more so because it is expected that genomics and proteomics will expand rapidly. However, it is likely that they will take a central place in the understanding, diagnosis, monitoring and treatment of (pre)cancers of many different sites.

Telomerase activity and telomerase subunit gene expression levels are not related in prostate cancer: a real-time quantification and in situ hybridization study

Because the mechanisms of telomerase activation in prostate cancer are mainly unknown, we investigated the relationships between telomerase activity and expression levels of human telomerase RNA (hTR) and human telomerase reverse transcriptase (hTERT) mRNA in benign and malignant alterations of the human prostate gland. Using the LightCycler technology, hTERT mRNA expression was quantified in 46 radical prostatectomy and 10 benign prostatic hyperplasia (BPH) cases; hTR expression was quantified in a subset of these tissue samples. Telomerase activity was measured using a quantitative telomeric repeat amplification protocol ELISA assay. Similar to hTR, which was expressed in all tissue samples tested, hTERT mRNA was detected in 98% of the prostate cancer samples and in 30% of the BPH samples. Regarding clinicopathologic variables, telomerase activity was significantly correlated with Gleason score (<7 vs > or =7, p = 0.02). No relationships emerged between normalized hTR or hTERT expression levels and tumor stage, Gleason score, lymph node status, or preoperative serum prostate-specific antigen. Remarkably, one third of all cancer and BPH tissue samples with hTR and hTERT expression lack telomerase activity. Quantitative analyses contradict the assumption that a certain threshold level of hTR or hTERT mRNA is required for telomerase activation, thus indicating that telomerase regulation in prostate cancer occurs more likely on a posttranscriptional level. Nevertheless, the observation that hTR and hTERT mRNA levels are significantly (p < 0.002) correlated suggests some common mechanisms in the up-regulation of hTR and hTERT expression. Because in situ hybridization revealed strong hTERT expression in all cells of the tumor glands but also in high-grade prostatic intraepithelial neoplasia foci, this up-regulation seems to occur early in prostate carcinogenesis.