Telomerase: its clinical relevance in the diagnosis of bladder cancer

Dual biomineralized metal-organic frameworks-mediated conversion of chemical energy to electricity enabling portable PEC sensing of telomerase activity in bladder cancer tissues

In this work, we report on a portable photoelectrochemical (PEC) sensing system for telomerase activity detection based on dual biomineralized ZIF-8 nanoparticles (NPs)-medicated conversion of chemical energy to electricity and terminal deoxynucleoside transferase (TdTase)-catalyzed elongation of Y-junction DNA structure. Two kinds of biomineralized ZIF-8 NPs including glucose oxidase (GOx)-encapsulated ZIF-8 (GZIF) and horseradish peroxidase (HRP)-encapsulated ZIF-8 (HZIF) are involved in this assay system. The recognition of telomerase is started with telomerase-catalyzed elongation of a telomerase substrate (TS) primer, which generates a longer elongation chain to trigger the formation of a Y-junction DNA structure. The Y-junction DNA with abundant 3'-OH terminal and small steric hindrance facilitates the implement of TdTase-catalyzed elongation reaction, in which the branches of Y-junction DNA are elongated and endowed with biotin moiety to capture streptavidin-modified GZIF (SA-GZIF). The signal transduction is then achieved on a luminol/HZIF/CdS-based photoelectrode. Once the H₂O₂ produced from GZIF-catalyzed hydrolysis of glucose is introduced to the photoelectrode, chemiluminescence of HRP-luminol-H₂O₂-p-iodo-phenol (PIP) system confined in HZIF is activated to excite photocurrent of CdS NPs, which is then recorded by a portable digital multimeter (DMM). The developed PEC sensing system possesses a wide calibration range from 50 to 5000 HeLa cells and a low detection limit of 46 cells. Significantly, the sensing platform is successfully applied to evaluate the telomerase activity in resected bladder tumor tissues. This work not only provides a diagnostic tool for telomerase-related diseases but also open a new avenue for establishing PEC assay methods using metal-organic framework (MOF) NPs.

Activating Telomerase TERT Promoter Mutations and Their Application for the Detection of Bladder Cancer

This review summarizes state-of-the-art knowledge in early-generation and novel urine biomarkers targeting the telomerase pathway for the detection and follow-up of bladder cancer (BC). The limitations of the assays detecting telomerase reactivation are discussed and the potential of transcription-activating mutations in the promoter of the TERT gene detected in the urine as promising simple non-invasive BC biomarkers is highlighted. Studies have shown good sensitivity and specificity of the urinary TERT promoter mutations in case-control studies and, more recently, in a pilot prospective cohort study, where the marker was detected up to 10 years prior to clinical diagnosis. However, large prospective cohort studies and intervention studies are required to fully validate their robustness and assess their clinical utility. Furthermore, it may be interesting to evaluate whether the clinical performance of urinary TERT promoter mutations could increase when combined with other simple urinary biomarkers. Finally, different approaches for assessment of TERT promoter mutations in urine samples are presented together with technical challenges, thus highlighting the need of careful technological validation and standardization of laboratory methods prior to translation into clinical practice.

Durvalumab: a newly approved checkpoint inhibitor for the treatment of urothelial carcinoma

Until a recent introduction to checkpoint inhibitors, there were limited second-line chemotherapy options for urothelial carcinoma (UC) patients with disease progression after first-line, platinum-based treatment. Outcomes for patients with advanced disease over the past 30 years have highlighted a need for new and better therapy. In response to evolving interest, durvalumab (MEDI4736) was introduced as a potential treatment for advanced stages of UC. Durvalumab is a selective, high-affinity, human IgG1 kappa monoclonal antibody engineered with a triple mutation to reduce toxicity. This checkpoint inhibitor has shown promise in advanced UC and is currently the topic of much discussion in the cancer research community. This review article will explore the details surrounding durvalumab, while also giving a brief overview of additional immunotherapeutic agents utilized for UC.

Clinical value of vascular endothelial growth factor and endostatin in urine for diagnosis of bladder cancer

Aims and background

The aim of the study was to determine whether urinary VEGF and endostatin predict the presence of bladder cancer, and whether these noninvasive biomarkers provide clinically useful information in the bladder cancer patient as well.

Methods and study design

Voided urine samples were collected from 239 patients (109 bladder cancers, 81 urological disorders, 49 healthy controls). The urine levels of VEGF and endostatin were determined with the sandwich enzyme immunoassay technique.

Results

Urine levels of VEGF and endostatin were higher in patients with bladder cancer than those in patients with urological disorders and healthy controls (P <0.01). The difference between patients with urological disorder and healthy controls was significant only for VEGF (P <0.01). Urine level of VEGF was related to the tumor grade, and urine level of endostatin was related to tumor stage, tumor size and tumor number (P <0.05). The optimal cutoffs for VEGF and endostatin were calculated by the ROC curves as 860 pg/ml for VEGF, and 350 pg/ml for endostatin. The five-year survival rate was 60.0% in patients with low level of endostatin (<350 pg/ml) and 7.69% in patients with high level of endostatin (≥350 pg/ml) in the bladder cancer group. Patients with a high level of endostatin had a shorter survival time, whereas patients with a low level of endostatin had a longer survival time (P <0.05).

Conclusions

Urine levels of VEGF and endostatin may be a clinically useful aid in the diagnosis of bladder cancer, and endostatin but not VEGF is a supplementary prognostic marker for predicting tumor progression.

Significance of p57Kip2 Down-Regulation in Oncogenesis of Bladder Carcinoma: An Immunohistochemical Study

Aims and Background

Cyclin-dependent kinase inhibitors have important roles in the oncogenesis of various tumors including urothelial cancer. The aim of this study was to establish the importance of p57Kip2, a unique cyclin-dependent kinase inhibitor, in the oncogenesis of bladder carcinoma. This article also focused on another cyclin-dependent kinase inhibitor, p27Kip1, and telomerase enzyme and examined the relationship between these proteins.

Material and Methods

Thirty-one patients with urothelial carcinomas of the bladder and 7 cases with normal urinary bladder mucosa were included in the study. Immunohistochemical study was performed by monoclonal antibodies of p27Kip1, p57Kip2, and the telomerase subunit (hTERT). All immunohistochemical preparations were evaluated by an immunohistochemical histological score.

Results

p57Kip2 and p27Kip1 expression were seen in all of the cases of normal mucosa. In carcinoma cases, 8 of 31 (25.8%) showed p57Kip2 nuclear positivity and 20 of 31 (64.5%) expressed nuclear p27Kip1. HSCOREs of carcinoma cases showed lower scores of nuclear p57Kip2 and p27Kip1 than normal mucosa, but only HSCOREs of nuclear p57Kip2 (P = 0 001) showed statistical significance. Despite unknown significance, cytoplasmic p57Kip2 and p27Kip1 were also evaluated. Immunohistochemical analysis showed that carcinomas expressed higher HSCOREs of hTERT than normal mucosa, and there was a significant difference (P = 0.026) between muscle invasive carcinomas and normal mucosa.

Conclusions

The data showed that p57Kip2 down-regulation along with p27Kip1 is a well-established feature of urothelial carcinoma. Probably, this down-regulation of cyclin-dependent kinase inhibitors supports the proliferation phase of oncogenesis. In the study, we also showed that hTERT expression was up-regulated in higher stages of urothelial carcinoma.

Evaluation of Cell-free DNA in Urine as a Marker for Bladder Cancer Diagnosis

The diagnosis and follow-up of bladder cancer are mainly based on cystoscopy, an invasive method which could be negative in case of flat malignancies such as carcinoma in situ. Other noninvasive diagnostic methods have not yet given satisfactory results. There is a need for a reliable yet noninvasive method for the detection of bladder cancer. Our aim was to investigate whether cell-free DNA quantified in urine (ucf-DNA) could be a useful marker for the diagnosis of bladder cancer.

A standard urine test was performed in 150 naturally voided morning urine samples that were processed to obtain a quantitative evaluation of ucf-DNA. Leukocyturia and/or bacteriuria were found in 18 subjects, who were excluded from the study. Statistical analysis was performed on 45 bladder cancer patients and 87 healthy subjects. Ucf-DNA was extracted from urine samples by a spin column-based method and quantified using four different methods: GeneQuant Pro (Amersham Biosciences, Pittsburg, PA, USA), Quant-iT™ DNA high-sensitivity assay kit (Invitrogen, Carlsbad, CA, USA), Real-Time PCR (Applied Biosystems, Foster City, CA, USA), and NanoDrop 1000 (NanoDrop Technologies, Houston, TX, USA). Median free DNA quantification did not differ statistically between bladder cancer patients and healthy subjects.

A receiver-operating characteristic (ROC) curve was developed to evaluate the diagnostic performance of ucf-DNA quantification for each method. The area under the ROC curve was 0.578 for GeneQuant Pro, 0.573 for the Quant-iT™ DNA high-sensitivity assay kit, 0.507 for Real-Time PCR, and 0.551 for NanoDrop 1000, which indicated that ucf-DNA quantification by these methods is not able to discriminate between the presence and absence of bladder cancer. No association was found between ucf-DNA quantification and tumor size or tumor focality.

In conclusion, ucf-DNA isolated by a spin column-based method and quantified by GeneQuant Pro, Quant-iT™ DNA high-sensitivity assay kit, Real-Time PCR or NanoDrop 1000 does not seem to be a reliable marker for the diagnosis of bladder cancer.

Molecular markers in bladder cancer: Novel research frontiers

Bladder cancer (BC) is a heterogeneous disease encompassing distinct biologic features that lead to extremely different clinical behaviors. In the last 20 years, great efforts have been made to predict disease outcome and response to treatment by developing risk assessment calculators based on multiple standard clinical-pathological factors, as well as by testing several molecular markers. Unfortunately, risk assessment calculators alone fail to accurately assess a single patient's prognosis and response to different treatment options. Several molecular markers easily assessable by routine immunohistochemical techniques hold promise for becoming widely available and cost-effective tools for a more reliable risk assessment, but none have yet entered routine clinical practice. Current research is therefore moving towards (i) identifying novel molecular markers; (ii) testing old and new markers in homogeneous patients' populations receiving homogeneous treatments; (iii) generating a multimarker panel that could be easily, and thus routinely, used in clinical practice; (iv) developing novel risk assessment tools, possibly combining standard clinical-pathological factors with molecular markers. This review analyses the emerging body of literature concerning novel biomarkers, ranging from genetic changes to altered expression of a huge variety of molecules, potentially involved in BC outcome and response to treatment. Findings suggest that some of these indicators, such as serum circulating tumor cells and tissue mitochondrial DNA, seem to be easily assessable and provide reliable information. Other markers, such as the phosphoinositide-3-kinase (PI3K)/AKT (serine-threonine kinase)/mTOR (mammalian target of rapamycin) pathway and epigenetic changes in DNA methylation seem to not only have prognostic/predictive value but also, most importantly, represent valuable therapeutic targets. Finally, there is increasing evidence that the development of novel risk assessment tools combining standard clinical-pathological factors with molecular markers represents a major quest in managing this poorly predictable disease.

Pathobiology and chemoprevention of bladder cancer

Our understanding of the pathogenesis of bladder cancer has improved considerably over the past decade. Translating these novel pathobiological discoveries into therapies, prevention, or strategies to manage patients who are suspected to have or who have been diagnosed with bladder cancer is the ultimate goal. In particular, the chemoprevention of bladder cancer development is important, since urothelial cancer frequently recurs, even if the primary cancer is completely removed. The numerous alterations of both oncogenes and tumor suppressor genes that have been implicated in bladder carcinogenesis represent novel targets for therapy and prevention. In addition, knowledge about these genetic alterations will help provide a better understanding of the biological significance of preneoplastic lesions of bladder cancer. Animal models for investigating bladder cancer development and prevention can also be developed based on these alterations. This paper summarizes the results of recent preclinical and clinical chemoprevention studies and discusses screening for bladder cancer.

The current role of telomerase in the diagnosis of bladder cancer

Bladder cancer has an incidence of 15 cases per 100,000 persons in the global population and is the most common tumor of the urinary tract. Imaging techniques, cytoscopy, and cytology are either invasive or not sufficiently accurate to detect early stage tumors, and the need for new diagnostic markers still remains. Among the markers most recently proposed to improve diagnostic accuracy and especially sensitivity, increasing attention has been focused on the role of the ribonucleoprotein, telomerase. Relevant papers on the etiology, diagnosis, and evaluation of bladder cancer using telomerase in urine were searched for and considered. The PubMed search was performed using the text terms "bladder cancer", "diagnosis", and "telomerase". Previous studies have shown that the quantitative Telomerase Repeat Amplification Protocol (TRAP) assay performed in voided urine is an important non-invasive tool for the diagnosis of bladder tumors since it has very high sensitivity and specificity, even for early stage and low grade tumors. The main limitation of this test is the rate of false positive results due to the presence of inflammatory or non-tumor cells (i.e., epithelial cells from the lower genital tract), which express telomerase activity (TA). Consequently, an in situ analysis would seem to be important to identify the nature of telomerase-positive cells. Immunocytochemical detection of the hTERT subunit by a specific antibody seemed to open up the possibility to identify different cellular components of urine. However, the lack of a strict relationship between hTERT protein expression and telomerase activity has, to a certain extent, made this approach less relevant. In conclusion, telomerase activity in urine determined by TRAP seems to be marker of great potential, even more advantageous in cost/benefit terms when used in selected symptomatic patients or professionally high-risk subgroups.

Telomerase mRNA detection in serum of patients with prostate cancer

Telomerase functions as a reverse transcriptase enzyme in the process of telomere synthesis and telomerase activity have been detected in a large part of neoplastic tissues, whereas in normal somatic cells they were low or undetectable. The aim of this study was to investigate the telomerase mRNA detection in the serum of patients with a prostate tumor by using real-time reverse transcription PCR. The results were compared with biological samples obtained by age-matched normal donors and by patients with cardiovascular or metabolic diseases. Our data demonstrated that telomerase mRNA is detectable in the serum of patients with prostate cancer whereas it is not amplifiable in normal donors. This marker, assayed with the molecular method of quantitative PCR in serum, may be useful for diagnosing and monitoring prostate cancer patients.

Down-regulation of TERE1/UBIAD1 activated Ras-MAPK signalling and induced cell proliferation

TERE1/UBIAD1 is involved in SCCD (Schnyder crystalline corneal dystrophy) and multiple human cancers. So far, the molecular mechanism of TERE1/UBIAD1 in tumourigenesis is unclear. Here, the expression levels of hTERT and TERE1/UBIAD1 in pathologically proven Chinese TCC (transitional cell carcinoma) samples were measured. It was found that decreased TERE1/UBIAD1 expression is closely related to both an increased hTERT expression and activation of Ras–MAPK signalling. Chemically modified TERE1 siRNA oligos were used to knock down TERE1 expression in human L02 cells. Cells transfected with TERE1 siRNA oligos underwent significant cell proliferation. When the levels of hTERT expression and ERK phosphorylation were measured, it was found that both of them increased in the above transfected cells, suggesting the activation of Ras–MAPK signalling. Addition of the MEK inhibitor U0126 into the transfected L02 cells described above inhibited ERK phosphorylation and hTERT expression. Our result is the initial demonstration that down-regulation of TERE1 activates Ras–MAPK signalling and induces subsequent cell proliferation. TERE1 might be a new negative regulator of Ras–MAPK signalling, which plays a pivotal role in the cell proliferation of multiple human cancers.

Expression and biological-clinical significance of hTR, hTERT and CKS2 in washing fluids of patients with bladder cancer

BACKGROUND

at present, pathogenesis of bladder cancer (BC) has not been fully elucidated. Aim of this study is to investigate the role of human telomerase RNA (hTR), human telomerase reverse transcriptase (hTERT) and CDC28 protein kinase regulatory subunit 2 (CKS2) in bladder carcinogenesis and their possible clinical significance;

METHODS

the transcript levels of hTR, hTERT and CKS2 were quantified by Real time reverse transcriptase chain reaction in exfoliated cells from bladder washings of 36 patients with BC and 58 controls. The statistical significance of differences between BC bearing patients and control groups, in the general as well as in the stratified analysis (superficial or invasive BC), was assessed by Student's t test. Non parametric Receiver Operating Characteristics analysis (ROC) was performed to ascertain the accuracy of study variables to discriminate between BC and controls. The clinical value of concomitant examination of hTR, hTERT and CKS2 was evaluated by logistic regression analysis;

RESULTS

a significant decrease in hTR and a significant increase in hTERT or CKS2 gene expression were found between BC bearing patients and controls, as well as in the subgroups analysis. The area under the curve (AUC) indicated an average discrimination power for the three genes, both in the general and subgroups analysis, when singularly considered. The ability to significantly discriminate between superficial and invasive BC was observed only for hTR transcript levels. A combined model including hTR and CKS2 was the best one in BC diagnosis;

CONCLUSIONS

our results, obtained from a sample set particularly rich of exfoliated cells, provide further molecular evidence on the involvement of hTR, hTERT and CKS2 gene expression in BC carcinogenesis. In particular, while hTERT and CKS2 gene expression seems to have a major involvement in the early stages of the disease, hTR gene expression, seems to be more involved in progression. In addition, our findings suggest that the studied genes have a clinical role in discriminating between BC and controls in the general as well as in the stratified analysis, when singularly considered. A combined model improved over the single marker BC diagnosis.

CK20 and Ki-67 as significant prognostic factors in human bladder carcinoma

Aberrant expression of CK20 and Ki-67 has been documented in many kinds of primary tumors and has proved useful as an ancillary diagnostic aid for those tumors. The aim of this study was to analyze the expression patterns of CK20 and Ki-67 in human bladder carcinomas (BCa) and to evaluate their clinical significance in the progression of BCa. CK20 and Ki-67 expression in BCa and normal bladder tissues were detected by immunohistochemical staining. The Spearman correlation was calculated between the expression of CK20 and Ki-67 in BCa tissues. The correlation of CK20 and Ki-67 expression with the clinicopathological characteristics and the prognosis of BCa were subsequently assessed. CK20 expression was positively expressed in 103/154 (66.9%) of BCa and 2/30 (6.67%) of normal bladder tissues, respectively. The positive expression rate of Ki-67 in BCa tissues was also significantly higher than those in normal bladder tissues (81.8 vs. 10%, p < 0.01). The Spearman analysis indicated that the expression level of CK20 has a significant positive correlation with that of Ki-67 (rs = 0.86, p = 0.02). Pathologic findings demonstrated that the intensity of CK20 and Ki-67 staining in cancerous tissues was associated significantly with tumor grades (p = 0.03, p < 0.01), distant metastasis (both p < 0.01) and TNM grades (p = 0.01, p = 0.03) of BCa. The progression-free survival of the patients with CK20 (+)/Ki-67 (+) expression was poorest (p < 0.01). The results suggest that the expression of CK20 and Ki-67 may be an important feature of BCa, and the detection of their co-expression may benefit the prediction of BCa prognosis.

Molecular markers for detection, surveillance and prognostication of bladder cancer

Many markers for the detection of bladder cancers have been tested and almost all urinary markers reported are better than cytology with regard to sensitivity, but they score lower in specificity. Currently molecular and genetic changes play an important role in the discovery of new molecular markers for detection, prognostication and surveillance. The purpose of this review is to highlight the most important urinary molecular biomarker developments that have been studied and reported recently. In the current review we have summarized the most recent and relevant published reports on molecular urinary markers. The results of this review show that the first generation of urinary markers did not add much to urinary cytology. The current generation of markers is better, but additional clinical trials are needed. Our knowledge of molecular pathways in bladder cancer is growing and new methods of marker development emerge, but the perfect marker is still to be found. Currently, there are not clinically usable molecular markers that can guide us in diagnosis or surveillance, nor guide us in lowering the frequency of urethrocystoscopy in bladder cancer.

Human telomerase reverse transcriptase (hTERT): a target molecule for the treatment of cisplatin-resistant tumors

BACKGROUND

Human telomerase reverse transcriptase (hTERT) is a catalytic enzyme that is required for telomerase activity (TA) and cancer progression. Telomerase inhibition or inactivation increases cellular sensitivity to UV irradiation, DNA-damaging agents, the tyrosine kinase inhibitor, imatinib, and pharmacological inhibitors, such as BIBR1532. hTERT is associated with apoptosis. Some patients show drug-resistance during anti-cancer drug treatment and the cancer cell acquire anti-apoptotic mechanism. Therefore, we attempted to study correlation between hTERT and drug-resistance.

METHODS

To study the correlation between protein level and activity of hTERT and drug-resistance, Western blotting and telomerase repeat amplification protocol (TRAP) assays were performed. To investigate whether hTERT contributes to drug resistance in tumor cells, we transiently decreased hTERT levels using small interfering RNA (siRNA) in T24/R2 cells.

RESULTS

hTERT knockdown increased Bax translocation into the mitochondria and cytochrome C release into the cytosol. Caspase inhibitors, especially Z-VAD-FMK, rescued this phenomenon, suggesting that the stability or expression of hTERT might be regulated by caspase activity.

CONCLUSIONS

These data suggest that hTERT might be a target molecule for drug-resistant tumor therapy.

Detection of circulating tumor cells in bladder cancer patients

The methods employed for the detection of circulating bladder cancer cells (CBCs) and their use as a molecular staging tool in clinical settings are thoroughly reviewed. CBC isolation and enrichment methods are discussed according to their advantages and pitfalls along with the clinical data of PCR-based techniques used for CBC detection. In addition, we review the specificity of molecular markers that have been proposed so far for CBC identification, and we comment on the controversial clinical data, proposing laboratory approaches which may improve the clinical significance of CBC detection in bladder cancer.

Genes involved in differentiation, stem cell renewal, and tumorigenesis are modulated in telomerase-immortalized human urothelial cells

The expression of hTERT, the catalytic subunit of telomerase, immortalizes normal human urothelial cells (NHUC). Expression of a modified hTERT, without the ability to act in telomere maintenance, did not immortalize NHUC, confirming that effects at telomeres are required for urothelial immortalization. Previous studies indicate that inhibition of telomerase has an immediate effect on urothelial carcinoma (UC) cell line viability, before sufficient divisions to account for telomere attrition, implicating non-telomere effects of telomerase in UC. We analyzed the effects of telomerase on gene expression in isogenic mortal and hTERT-transduced NHUC. hTERT expression led to consistent alterations in the expression of genes predicted to be of phenotypic significance in tumorigenesis. A subset of expression changes were detected soon after transduction with hTERT and persisted with continued culture. These genes (NME5, PSCA, TSPYL5, LY75, IGFBP2, IGF2, CEACAM6, XG, NOX5, KAL1, and HPGD) include eight previously identified as polycomb group targets. TERT-NHUC showed overexpression of the polycomb repressor complex (PRC1 and PRC4) components, BMI1 and SIRT1, and down-regulation of multiple PRC targets and genes associated with differentiation. TERT-NHUC at 100 population doublings, but not soon after transduction, showed increased saturation density and an attenuated differentiation response, indicating that these are not acute effects of telomerase expression. Some of the changes in gene expression identified may contribute to tumorigenesis. Expression of NME5 and NDN was down-regulated in UC cell lines and tumors. Our data supports the concept of both telomere-based and non-telomere effects of telomerase and provides further rationale for the use of telomerase inhibitors in UC.

A novel magnetic bead-based assay with high sensitivity and selectivity for analysis of telomerase in exfoliated cells from patients with bladder and colon cancer

Telomerase activity is elevated in more than 85% of cancer cells and absent in most of the normal cells and thus represents a potential cancer biomarker. We report its measurement in colon and bladder cancer cells captured using antibody-coated magnetic beads. The cells are lysed and telomerase activity is detected using a biosensor assay that employs an oligonucleotide containing the telomerase recognition sequence also covalently coupled to magnetic beads. Telomerase activity is measured by the incorporation of multiple biotinylated nucleotides at the 3'-end of the oligonucleotide strands during elongation which are then reacted with streptavidin-conjugated horseradish peroxidase. A luminescent signal is generated when hydrogen peroxidase is added in the presence of luminol and a signal enhancer. LOD experiments confirm sensitivity down to ten cancer cell equivalents. The telomerase assay reliably identified patient samples considered by an independent pathological review to contain cancer cells. Samples from normal healthy volunteers were all telomerase negative. The assay, which is amenable to automation, demonstrated high sensitivity and specificity in a small clinical cohort, making it of potential benefit as a first line assay for detection and monitoring of colon and bladder cancer.

Road for understanding cancer stem cells: model cell lines

There is increasing evidence suggesting that stem cells are susceptive to carcinogenesis and, consequently, can be the origin of many cancers. Recently, the neoplastic potential of stem cells has been supported by many groups showing the existence of subpopulations with stem cell characteristics in tumor biopsies such as brain and breast. Evidence supporting the cancer stem cell hypothesis has gained impact due to progress in stem cell biology and development of new models to validate the self-renewal potential of stem cells. Recent evidence on the possible identification of cancer stem cells may offer an opportunity to use these cells as future therapeutic targets. Therefore, model systems in this field have become very important and useful. This review will focus on the state of knowledge on cancer stem cell research, including cell line models for cancer stem cells. The latter will, as models, help us both in the identification and characterization of cancer stem cells and in the further development of therapeutic strategies including tissue engineering.

Tankyrase-1 mRNA expression in bladder cancer and paired urine sediment: preliminary experience

BACKGROUND

The enzyme tankyrase-1 (TNKS-1), a member of the growing family of poly(ADP-ribose) polymerases (PARPs), was identified as a component of the human telomeric complex. PARPs catalyze the formation of long chains of poly(ADP-ribose) onto protein acceptors using NAD(+) as a substrate. TNKS-1 interacts with the telomeric DNA-binding protein TTAGGG repeat-binding factor 1 (TRF1), which is a negative regulator of telomere length. TNKS-1 is a positive regulator of telomere elongation and its activity appears to be upregulated in some human cancers.

METHODS

We evaluated for the first time TNKS-1 mRNA expression by real time RT-PCR in tumor tissue, paired normal mucosa and urine sediment in patients with transitional cell carcinoma (TCC) of the bladder. Samples were collected from 41 consecutive patients, 20 with non-muscle-invasive (pTa-pT1) and 21 with muscle-invasive (>/=pT2) bladder TCC. Results obtained in urine sediment were compared with those from 40 healthy subjects matched for age and sex.

RESULTS

In pTa-pT1 tumor tissues, TNKS-1 mRNA levels were significantly higher than in >/=pT2 patients (p<0.0001). In urine sediment from TCC patients, independent of tumor stage, TNKS-1 mRNA levels were significantly higher than in healthy controls, with maximal levels in >/=pT2 patients. In particular, TNKS-1 mRNA levels in urine were elevated in 31/41 patients with a sensitivity of 81% in >/=pT2 tumors and 65% in pTa-pT1 TCC. Of patients with pTa-pT1 tumors, 11 had a recurrence within 18 months after initial transurethral resection. In these patients, urine levels of TNKS-1 mRNA were higher than in non-relapsing patients (p=0.038).

CONCLUSIONS

In this preliminary study, TNKS-1 mRNA in urine sediment from patients with bladder TCC correlated with tumor stage, and higher preoperative levels were associated with increased risk of early recurrence.

Detection of telomerase in urine by 3 methods: evaluation of diagnostic accuracy for bladder cancer

PURPOSE

New, noninvasive methods are needed for the diagnosis, followup and screening of patients with bladder cancer. Three methods of detecting telomerase were evaluated in this aspect.

MATERIALS AND METHODS

This study included 200 patients diagnosed with bladder carcinoma, 85 with benign bladder lesions and 30 healthy individuals who served as the control group. All underwent serological schistosomiasis antibody assay in serum, urine cytology and estimation of relative telomerase activity by telomeric repeat amplification protocol, human telomerase RNA by reverse transcriptase-polymerase chain reaction and human telomerase reverse transcriptase by real-time reverse transcriptase-polymerase chain reaction in urothelial cells from voided urine.

RESULTS

The concordance between the positive rates of telomerase detected by the 3 methods was high (90% to 95%). Results were significantly higher in the malignant group than in the benign and control groups. There was a significant difference among the results of the 3 methods in relation to different clinicopathological factors. Overall the sensitivity of human telomerase reverse transcriptase for detecting bladder cancer was the highest compared to that of human telomerase RNA, relative telomerase activity and urine cytology (96%, 92%, 75% and 75%, respectively). Combinations of telomerase results with urine cytology were not useful except in cases of relative telomerase activity.

CONCLUSIONS

Detection of human telomerase reverse transcriptase in urine by real-time polymerase chain reaction, followed by human telomerase RNA by reverse transcriptase-polymerase chain reaction, improves sensitivity and specificity for the diagnosis of bladder cancer. However, regarding cost-effectiveness, human telomerase RNA is superior.

Gene manipulation to enhance MIBG-targeted radionuclide therapy

The goal of targeted radionuclide therapy is the deposition in malignant cells of sterilizing doses of radiation without damaging normal tissue. The radiopharmaceutical [(131)I]meta-iodobenzylguanidine ([(131)I]MIBG) is an effective single agent for the treatment of neuroblastoma. However, uptake of the drug in malignant sites is insufficient to cure disease. A growing body of experimental evidence indicates exciting possibilities for the integration of gene transfer with [(131)I]MIBG-targeted radiotherapy.

Detection of telomerase activity in gastric lavage fluid: a novel method to detect gastric cancer

BACKGROUND

Telomerase is a ribonucleoprotein polymerase that is essential for cell immortality. Recent studies have demonstrated that a high percentage of gastric cancer tissue expressed telomerase. This study describes the presence of telomerase activity in gastric lavage fluid in patients with gastric cancer.

METHODS

Gastric lavage fluid was collected during esophageogastroduodenoscopy in 70 patients: 25 with gastric cancer, 25 with peptic ulcer disease, and 20 with normal stomach. The fluid and biopsy samples were analyzed for telomerase activity by a polymerase chain reaction-based telomerase repeat amplification protocol. The findings were related to the histological results.

RESULTS

Telomerase activity was present in 24 of the 25 (96%) gastric cancer tissue and in 7 of the 25 tissue specimens from peptic ulcer or gastritis. In the gastric lavage fluid, telomerase was detected in 20 patients (80%) with gastric cancer, 7 patients (28%) with peptic ulcer, and none in normal subjects (P < 0.001). The sensitivity, specificity, positive predictive value, and negative predictive value of gastric fluid telomerase expression in gastric cancer patients was 80%, 84%, 74%, and 88%, respectively.

CONCLUSIONS

The presence of telomerase activity is present in gastric lavage fluid of patients with gastric cancer as compared to those without, may represent a novel method for diagnosis of gastric cancer.

The clinical significance of molecular markers to bladder cancer

Stage and grade of transitional cell carcinoma are currently the most useful tools for taking therapeutic decisions and evaluating the prognosis of bladder cancer patients. However, as there are remarkable differences in biological behavior and "biological potential" of tumors classified in the same stage, it is very difficult to predict which superficial tumors will recur and which tumors will give distant metastases. During the last two decades, the better understanding of the molecular mechanisms involved in carcinogenesis and tumor progression has provided a large number of molecular markers of bladder cancer, with a potential diagnostic and prognostic value. This article reviews comprehensively the molecular role and evaluates the clinical significance and the perspectives of these molecular markers. We concluded that, although at the moment there is not a single marker able to predict with accuracy the biological potential of bladder cancer, the most promising markers, at this point, are deletions of chromosome 9, and the tumor suppressor gene p53. Clinical studies are in progress for the assessment of other biological molecules with prognostic potential, such as the E-cadherin, the protein p120, and the telomerase.

The Simultaneous Use of Telomerase, Cytokeratin 20 and CD4 for Bladder Cancer Detection in Urine

OBJECTIVE

Because of the low sensitivity of urinary cytological diagnosis of urinary bladder carcinoma, new molecular diagnostic methods have been proposed. We decided to verify the expression of telomerase mRNA coding for the catalytic component (hTRT), cytokeratin 20 (CK20) and CD4 antigen mRNAs in urine as possible diagnostic tool.

METHODS

Evaluation of hTRT, CK20, CD4 mRNAs was performed in 50 ml of naturally voided urine of 205 patients of which 153 with bladder cancer (Tis, n = 11; TaGx, n = 4; TaG1, n = 25; TaG2, n = 26; TaG3, n = 8; T1G1, n = 16; T1G2, n = 17; T1G3, n = 20; T2G2, n = 6; T2G3, n = 13; T3G3, n = 7) and 52 controls. A quantitative expression of hTRT at mRNA level versus TRAP (telomeric repeat amplification protocol) assay was performed in 20 patients and 14 controls. The expression of RT-PCR for hTRT, CK20, CD4 versus urinary cytology was analysed in 44 patients with bladder cancer. Evaluating the three molecular markers together, the result was considered correct when at least two of the markers were positive, suspected when only one marker was positive and negative for diagnosis of tumour when all markers were negative. The performance of the diagnostic model resulted from the logistic analysis evaluated with receiver operating characteristics (ROC) curve analysis.

RESULTS

The sensitivity detected for each tumour marker was as follows: for hTRT 90.8%, for CK20 84.3% and for CD4 was 64.7%, while the specificity was 94.2% for CD4 and 78.8% for both hTRT and CK20. When a simultaneous evaluation of the three tumour markers was considered, 88.2% of the diagnoses were correct, 11.8% were suspected for tumour and none were mistaken. When compared with cytology, the simultaneous use of the three markers allowed reaching a correct diagnosis in 88% of the cases in comparison to 25% by urinary cytology. The sensitivity in the detection of bladder cancer was higher for hTRT at mRNA level in comparison with the enzymatic activity detection with TRAP (90% vs. 35%) while the specificity for both markers resulted very high (100%).

CONCLUSIONS

These data show that in the future the diagnostic improvement of urine based molecular markers for the detection of bladder cancer in the urine could improve the sensitivity of urinary cytology reducing the need of a cystoscopy.

Application of Targeted Radiotherapy/Gene Therapy to Bladder Cancer Cell Lines

OBJECTIVES

A targeted radiotherapy/gene therapy strategy for transitional cell carcinoma of bladder is described, using [131I]meta-iodobenzylguanidine ([131I]MIBG), a radionuclide combined with a tumour-seeking drug. The aim is to decrease side effects from radiation toxicity, while increasing radiation dose to tumour. This tumour cell kill approach is augmented by radiological bystander effects.

METHODS

The bladder cancer cell line EJ138 was transfected with a gene encoding the noradrenaline transporter (NAT) under the control of tumour-specific telomerase promoters. Resulting uptake of [131I]MIBG was assessed by gamma-counting of cell lysates, and NAT transgene expression by real-time RT-PCR. Cell kill of monolayers and disaggregated spheroids, dosed with [131I]MIBG, was assessed by clonogenic assay.

RESULTS

NAT gene transfected cells exhibited a significantly increased active uptake of [131I]MIBG, leading to dose-dependent cell kill. Clonogenic assay of disaggregated spheroids, a three-dimensional model, suggested cell kill via bystander effects.

CONCLUSIONS

Expression of a functional NAT after in vitro transfection of bladder cancer cells with the NAT gene under the control of telomerase promoters leads to active uptake of [131I]MIBG and dose-dependent cell kill. This strategy could produce a promising new treatment option for bladder cancer.

Quantitative evaluation of telomerase subunits in urine as biomarkers for noninvasive detection of bladder cancer

The aim of our study was to prospectively evaluate the potential diagnostic value and clinical applicability of quantitative analysis of telomerase subunits gene expression in urine for noninvasive detection of bladder cancer. Expression levels of human telomerase reverse transcriptase (hTERT) and human telomerase RNA (hTR) were analyzed by real-time reverse transcriptase polymerase chain reaction (RT-PCR) in urine samples from 163 subjects with bladder cancer and 237 controls (163 individuals with benign genitourinary diseases; 74 healthy subjects). The sensitivity, specificity and optimal cutoffs were determined and compared to the corresponding values obtained by voided urine cytology. Quantitative urinary hTR analysis detects bladder cancer with an overall sensitivity of 77.0%, whereas hTERT analysis reached a sensitivity of 55.2%. The majority of undetected tumors were small, low-grade pTa lesions. Both hTR and hTERT proved to be significantly more sensitive than cytology (34.5%; p < 0.001). Specificities for hTR, hTERT and cytology were 72.1%, 85.0% and 92.7%, respectively, in the total study population and 96.9%, 89.2% and 100%, respectively, in healthy subjects. Higher diagnostic accuracy was achieved by hTR than by hTERT analysis (p < 0.05). The specificity of hTR increased to 85.0% in the total population if urinary leukocyte contamination was excluded. These data suggest that quantitative hTR analysis is the most accurate telomerase-based test for bladder cancer detection and has the potential to replace cytology as a noninvasive biomarker for disease diagnosis and follow-up.

Urine telomerase: an important marker in the diagnosis of bladder cancer

Telomerase activity is present in most human malignant tumors, whereas it is generally not detectable, with some exceptions, in normal cells. Therefore, it represents a potential tool for tumor detection. In the present study, telomerase activity was determined in urine from 79 healthy individuals and 121 previously untreated bladder cancer patients using a highly sensitive telomeric repeat amplification protocol (TRAP) assay and the results were expressed as arbitrary enzymatic units (AEU). This approach enabled us to identify cutoff values characterized by high sensitivity (from 75% to 93%) and specificity (from 72% to 92%). Moreover, analysis as a function of gender showed a higher accuracy of TRAP assay in males (93% sensitivity and 90% specificity at the cutoff of 50 AEU) than in females. This sensitivity was confirmed in patients with nonassessable or negative cytology. In women, morphological and immunocytochemical determinations using a monoclonal antibody (anti-hTERT) recently developed in our laboratory showed a large fraction of immunoreactive inflammatory or nonbladder cells, which may justify the false-positive TRAP results. In conclusion, this assay represents an important noninvasive diagnostic tool to detect bladder cancer also in patients with negative or nonassessable urine cytology and with low-grade and early-stage lesions.

Advances in the clinical laboratory assessment of urinary sediment

Urinalysis has been used extensively in clinical practice to aid in the diagnosis of various renal and urologic diseases. The innovation of urinalysis is marching on right along with the rapid developments in biotechnology and astride from the solo urine cytology to sophisticated studies of individual component in the urinary sediment. In this review article, we focus on the use of flow cytometry and other technical advances in the examination of urinary sediment, the detection of urologic malignancies by the presence of microsatellite alteration in the urinary sediment, as well as the quantification of cytokine messenger RNA (mRNA) expression in urinary sediment by reverse transcription and real-time quantitative polymerase chain reaction (RT-QPCR). Notably, the study of cytokine mRNA expression in urinary sediment by RT-QPCR has recently been reported to provide important diagnostic information in kidney allograft recipients and patients with lupus nephritis. This simple and non-invasive method requires further study to determine its role in risk stratification and monitoring of therapeutic response in patients with other kidney diseases.

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.

Molecular detection of noninvasive and invasive bladder tumor tissues and exfoliated cells by aberrant promoter methylation of laminin-5 encoding genes

Laminin-5 (LN5) anchors epithelial cells to the underlying basement membrane, and it is encoded by three distinct genes: LAMA3, LAMB3, and LAMC2. To metastasize and grow, cancer cells must invade and destroy the basement membrane. Our previous work has shown that epigenetic inactivation is a major mechanism of silencing LN5 genes in lung cancers. We extended our methylation studies to resected bladder tumors (n = 128) and exfoliated cell samples (bladder washes and voided urine; n = 71) and correlated the data with clinicopathologic findings. Nonmalignant urothelium had uniform expression of LN5 genes and lacked methylation. The methylation frequencies for LN5 genes in tumors were 21-45%, and there was excellent concordance between methylation in tumors and corresponding exfoliated cells. Methylation of LAMA3 and LAMB3 and the methylation index were correlated significantly with several parameters of poor prognosis (tumor grade, growth pattern, muscle invasion, tumor stage, and ploidy pattern), whereas methylation of LAMC2 and methylation index were associated with shortened patient survival. Of particular interest, methylation frequencies of LAMA3 helped to distinguish invasive (72%) from noninvasive (12%) tumors. These results suggest that methylation of LN5 genes has potential clinical applications in bladder cancers.

High levels of urinary midkine in various cancer patients

Midkine (MK) is a heparin-binding growth factor, which promotes growth, migration, and survival of various cells, and MK expression is increased in many human carcinomas. We determined the urinary MK level by enzyme-linked immunoassay. Taking 311pg/mg creatinine as a cut-off level, 70% of patients with various carcinomas (n=142) gave positive values, while only 5.5% of healthy volunteers (n=330) did. In case of gastric carcinoma, 17 out of 21 patients with stage 1 tumor were positive. Urinary MK levels are expected to become a convenient marker as an aid in detection of tumors.

[Molecular diagnostics in urologic oncology. Detection of nucleic acids in urine samples]

The goal of molecular diagnostics in oncology is the early diagnosis of malignant disease processes during initial work-up or as part of follow-up. Body fluids serve as the primary material for non-invasive diagnostic methods. Besides actual tumor cells, the examination of urine can yield evidence of secreted proteins or even free nucleic acids. In principle, all of the methods available for the detection of tumor markers in tissue or blood samples can be successfully applied to the examination of urine samples. However, molecular biological examination of urine samples is associated with important problems because the cells in such samples are exposed to significant degradation and regression effects and because certain components of the urine act to inhibit the polymerase chain reaction. The present overview discusses the respective strengths and weakness of the available technology as applied to the diagnosis of urologic malignancies. Experimental studies conducted to date have reported high sensitivities and specificities for molecular diagnostics using urine samples. It is important to note that not only carcinomas of the urinary bladder can be diagnosed from material obtained in urine samples: in fact, the method can be used to diagnose entities such as renal cell and prostate carcinomas and, due to renal filtration of DNA, even non-urologic malignancies. The diagnostic application of these methods, however, remains in an experimental stage and must still clear several hurdles before becoming available for routine clinical use.