Noninvasive Detection of Prostate Cancer by Quantitative Analysis of Telomerase Activity

Biosensors for prostate cancer detection

Prostate cancer (PC) is one of the most common tumors and a leading cause of mortality among men, resulting in ~375 000 deaths annually worldwide. Various analytical methods have been designed for quantitative and rapid detection of PC biomarkers. Electrochemical (EC), optical, and magnetic biosensors have been developed to detect tumor biomarkers in clinical and point-of-care (POC) settings. Although POC biosensors have shown potential for detection of PC biomarkers, some limitations, such as the sample preparation, should be considered. To tackle such shortcomings, new technologies have been utilized for development of more practical biosensors. Here, biosensing platforms for the detection of PC biomarkers such as immunosensors, aptasensors, genosensors, paper-based devices, microfluidic systems, and multiplex high-throughput platforms, are discussed.

Beyond liquid biopsy: Toward non-invasive assays for distanced cancer diagnostics in pandemics

Liquid biopsy technologies have seen a significant improvement in the last decade, offering the possibility of reliable analysis and diagnosis from several biological fluids. The use of these technologies can overcome the limits of standard clinical methods, related to invasiveness and poor patient compliance. Along with this there are now mature examples of lab-on-chips (LOC) which are available and could be an emerging and breakthrough technology for the present and near-future clinical demands that provide sample treatment, reagent addition and analysis in a sample-in/answer-out approach. The possibility of combining non-invasive liquid biopsy and LOC technologies could greatly assist in the current need for minimizing exposure and transmission risks. The recent and ongoing pandemic outbreak of SARS-CoV-2, indeed, has heavily influenced all aspects of life worldwide. Ordinary tasks have been forced to switch from “in presence” to “distanced”, limiting the possibilities for a large number of activities in all fields of life outside of the home. Unfortunately, one of the settings in which physical distancing has assumed noteworthy consequences is the screening, diagnosis and follow-up of diseases.

In this review, we analyse biological fluids that are easily collected without the intervention of specialized personnel and the possibility that they may be used -or not-for innovative diagnostic assays. We consider their advantages and limitations, mainly due to stability and storage and their integration into Point-of-Care diagnostics, demonstrating that technologies in some cases are mature enough to meet current clinical needs.

Development and validation of a 25-Gene Panel urine test for prostate cancer diagnosis and potential treatment follow-up

BACKGROUND

Heterogeneity of prostate cancer (PCa) contributes to inaccurate cancer screening and diagnosis, unnecessary biopsies, and overtreatment. We intended to develop non-invasive urine tests for accurate PCa diagnosis to avoid unnecessary biopsies.

METHODS

Using a machine learning program, we identified a 25-Gene Panel classifier for distinguishing PCa and benign prostate. A non-invasive test using pre-biopsy urine samples collected without digital rectal examination (DRE) was used to measure gene expression of the panel using cDNA preamplification followed by real-time qRT-PCR. The 25-Gene Panel urine test was validated in independent multi-center retrospective and prospective studies. The diagnostic performance of the test was assessed against the pathological diagnosis from biopsy by discriminant analysis. Uni- and multivariate logistic regression analysis was performed to assess its diagnostic improvement over PSA and risk factors. In addition, the 25-Gene Panel urine test was used to identify clinically significant PCa. Furthermore, the 25-Gene Panel urine test was assessed in a subset of patients to examine if cancer was detected after prostatectomy.

RESULTS

The 25-Gene Panel urine test accurately detected cancer and benign prostate with AUC of 0.946 (95% CI 0.963-0.929) in the retrospective cohort (n = 614), AUC of 0.901 (0.929-0.873) in the prospective cohort (n = 396), and AUC of 0.936 (0.956-0.916) in the large combination cohort (n = 1010). It greatly improved diagnostic accuracy over PSA and risk factors (p < 0.0001). When it was combined with PSA, the AUC increased to 0.961 (0.980-0.942). Importantly, the 25-Gene Panel urine test was able to accurately identify clinically significant and insignificant PCa with AUC of 0.928 (95% CI 0.947-0.909) in the combination cohort (n = 727). In addition, it was able to show the absence of cancer after prostatectomy with high accuracy.

CONCLUSIONS

The 25-Gene Panel urine test is the first highly accurate and non-invasive liquid biopsy method without DRE for PCa diagnosis. In clinical practice, it may be used for identifying patients in need of biopsy for cancer diagnosis and patients with clinically significant cancer for immediate treatment, and potentially assisting cancer treatment follow-up.

Telomere DNA Damage Signaling Regulates Prostate Cancer Tumorigenesis

Telomere shortening has been demonstrated in benign prostatic hypertrophy (BPH), which is associated with prostate epithelial cell senescence. Telomere shortening is the most frequently observed genetic alteration in prostatic intraepithelial neoplasia, and is associated with poor clinical outcomes in prostate cancer. Gene expression database analysis revealed decreased TRF2 expression during malignant progression of the prostate gland. We reasoned that reduced TRF2 expression in prostate epithelium, by activating the telomere DNA damage response, would allow us to model both benign and malignant prostate disease. Prostate glands with reduced epithelial TRF2 expression developed age- and p53-dependent hypertrophy, senescence, ductal dilation, and smooth muscle hyperplasia similar to human BPH. Prostate tumors with reduced TRF2 expression were classified as high-grade androgen receptor-negative adenocarcinomas, which exhibited decreased latency, increased proliferation, and distant metastases. Prostate cancer stem cells with reduced TRF2 expression were highly tumorigenic and maintained telomeres both by telomerase and alternative lengthening (ALT). Telomerase inhibition in prostate glands with reduced TRF2 expression produced significant reduction in prostate tumor incidence by halting progression at intraepithelial neoplasia (PIN). These lesions were highly differentiated, exhibited low proliferation index, and high apoptotic cell fraction. Prostate tumors with reduced TRF2 expression and telomerase inhibition failed to metastasize and did not exhibit ALT. IMPLICATIONS: Our results demonstrate that the telomere DNA damage response regulates BPH, PIN, and prostate cancer and may be therapeutically manipulated to prevent prostate cancer progression.

Evaluation of the Efficacy of Post Prostatic Massage Urine Cytology in Diagnosis of Various Prostatic Lesions with Cytohistological and Clinical Correlation

Background

Elderly men are at high risk of various prostatic diseases carrying high morbidity and mortality rates. For screening large populations, there is a need for a simple, reliable, and noninvasive test with high sensitivity and specificity. Exfoliated prostatic cancer cells can be harvested by prostatic massage and subjected to cytologic examination and molecular tests.

Aims

This study was undertaken to evaluate the morphology of various prostatic lesions on post prostatic massage urine cytology and correlate cytologic, histologic, and clinical findings. It was further proposed to establish the diagnostic accuracy of post prostatic massage urine cytology in different prostatic lesions.

Materials and Methods

Totally, 100 cases including 50 cases each from study group and control group were subjected to post prostatic massage urine cytology and correlated with clinical and histological findings.

Results

Five out of 50 cases were diagnosed as prostatic carcinoma, of which 60% were clinically detected. Diagnostic accuracy by histology and cytology independently was 80%, and 20% remained false negative by each technique. On combining both the techniques, diagnostic accuracy was 100%. For nine cases each of prostatitis and nodular hyperplasia diagnosed clinically, the diagnostic accuracy by cytology was 100 and 66.6%, respectively. 62% (31) cases were diagnosed as nodular hyperplasia including 22 (44%) cases of nodular hyperplasia with prostatitis.

Conclusion

Collection of urinary specimens after prostatic massage provides adequate samples for cytological examination and carries great importance in establishing the preoperative morphologic diagnosis in cases of malignancy, prostatitis, and prostatic calculi.

Circulating Prostate-Specific Antigen and Telomere Length in a Nationally Representative Sample of Men Without History of Prostate Cancer

BACKGROUND

We investigated the association of prostate-specific antigen (PSA) with leukocyte telomere length, which may be altered in preclinical prostate malignancies.

METHODS

This study was based on the 2001-2002 U.S. National Health and Nutrition Examination Survey (NHANES). A subsample of 1,127 men aged 40-85 years without prior history of prostate cancer who provided informed consent and blood samples were selected. Leukocyte telomere length (LTL) relative to standard DNA reference (T/S ratio) was quantified by polymerase chain reaction (PCR). Survey-weighted multivariable linear regression was performed to examine T/S ratio across quintiles of total and free PSA and free-to-total PSA ratio (%fPSA). A sensitivity analysis was performed by excluding men dying from prostate cancer during follow-up through to December 31, 2006. Stratification analyses were carried out to assess any effect modification by age group, race, body mass index (BMI), and levels of C-reactive protein (CRP), a marker of inflammation.

RESULTS

Higher total PSA levels were associated to longer LTL, with approximately 8% increase in log-transformed T/S ratio (95% confidence interval [CI]: 2-13%) among men in the highest quintile of total PSA compared to the lowest in the fully adjusted model (P_trend  = 0.01). No significant association was found for free PSA or %fPSA, although nonlinearity between all PSA measures and T/S ratio was indicated. Similar results were found after excluding men who died from prostate cancer during follow-up. We also found the associations between total PSA and T/S ratio to be strongest among non-Hispanic blacks, non-obese men (BMI <30 kg/m² ), and those with low CRP. However, a significant interaction was only found between total PSA and race/ethnicity (P_interaction  = 0.01).

CONCLUSION

Total PSA levels were strongly associated to LTL, particularly among non-Hispanic blacks. Our findings support a potential link between PSA and specific mechanisms contributing to prostate cancer development. Prostate 77:22-32, 2017. © 2016 Wiley Periodicals, Inc.

Molecular diagnosis of prostate cancer: are we up to age?

Prostate cancer (PCa), a highly heterogeneous disease, is the one of the leading cause of morbidity and mortality in the developed countries. Historically used biomarkers such as prostatic acid phosphatase (PAP), serum prostate-specific antigen (PSA), and its precursor have not stood the challenge of sensitivity and specificity. At present, there is need to re-evaluate the approach to diagnose and monitor PCa. To this end, molecular markers that can accurately identify men with PCa at an early stage, and those who would benefit from early therapeutic intervention, are the need of the hour. There has been unprecedented progress in the development of new PCa biomarkers through advancements in proteomics, tissue DNA and protein/RNA microarray, identification of microRNA, isolation of circulating tumor cells, and tumor immunohistochemistry. This review will examine the current status of prostate cancer biomarkers with emphasis on emerging biomarkers by evaluating their diagnostic and prognostic potentials.

Toward the detection of prostate cancer in urine: a critical analysis

PURPOSE

Prostate specific antigen and digital rectal examination have low specificity for detecting prostate cancer and they poorly predict the presence of aggressive disease. Urine is readily available and noninvasive, and it represents a promising source of biomarkers for the early detection and prediction of prostate cancer prognosis. We identified promising biomarkers for urine based prostate cancer, examined trends and outlined potential pitfalls.

MATERIALS AND METHODS

We performed PubMed® and Web of Science® database searches of the peer reviewed literature on urine based testing for prostate cancer. Original studies of this subject as well as a small number of reviews were analyzed, including the strengths and weaknesses. We provide a comprehensive review of urine based testing for prostate cancer that covers the technical aspects, including the methodology of urine collection, as well as recent developments in biomarkers spanning the fields of genomics, epigenetics, transcriptomics, proteomics and metabolomics.

RESULTS

The process of urine collection is subject to variability, which may result in conflicting clinical results. Detecting prostate cancer in urine is technically feasible, as demonstrated by numerous proof of principle studies, but few markers have been validated in multiple large sample sets. Biomarker development using urine has been accelerating in recent years with numerous studies identifying DNA, RNA, protein and metabolite based biomarkers in urine. Advanced clinical studies have identified PCA3 and TMPRSS2:ERG fusion transcripts as promising RNA markers for cancer detection and possibly prognosis. DNA methylation analysis of multiple genes improves specificity and represents a promising platform for developing clinical grade assays.

CONCLUSIONS

Urine based testing is noninvasive and represents a rich source of novel biomarkers for prostate cancer. Although urine shows promise for detecting cancer, the ability to identify aggressive subsets of prostate cancer needs further development.

Label-free highly sensitive detection of telomerase activity in cancer cell by chemiluminescence imaging

We have developed a new methodology for label-free highly sensitive telomerase activity assay using chemiluminescence imaging. This method can detect the telomerase activity from as little as 10 cultured cancer cells without PCR. Furthermore, telomerase inhibition is shown, demonstrating the potential for screening of telomerase inhibitors as anticancer drug agents.

Assays for human telomerase activity: progress and prospects

Human telomerase is a ribonucleoprotein complex that functions as a telomere terminal transferase by adding multiple TTAGGG hexamer repeats using its integral RNA as the template. There is a very strong association between telomerase activity and malignancy in nearly all types of cancer, suggesting that telomerase could be used not only as a diagnostic and prognostic marker but also as a therapeutic target for managing cancer. The significant progress in biomedical telomerase research has necessitated the development of new bioanalytical methods for the rapid, sensitive, and reliable detection of telomerase activity in a particular cell or clinical tissue and body fluids. In this review, we highlight some of the latest methods for identifying telomerase activity and inhibition and discuss some of the challenges for designing innovative telomerase assays. We also summarise the current technologies and speculate on future directions for telomerase testing.

The potential utility of telomere-related markers for cancer diagnosis

The role telomeres and telomerase play in the initiation and progression of human cancers has been extensively evaluated. Telomeres are nucleoprotein complexes comprising the hexanucleotide DNA repeat sequence, TTAGGG and numerous telomere-associated proteins, including the six member Shelterin complex. The main function of the telomere is to stabilize the ends of the chromosomes. However, through multiple mechanisms, telomeres can become dysfunctional, which may drive genomic instability leading to the development of cancer. The majority of human cancers maintain, or actively lengthen, telomeres through up-regulation of the reverse transcriptase telomerase. Because there are significant differences in telomere length and telomerase activity between malignant and non-malignant tissues, many investigations have assessed the potential to utilize these molecular markers for cancer diagnosis. Here, we critically evaluate whether measurements of telomere lengths and telomerase levels may be clinically utilized as diagnostic markers in solid tumours, with emphasis on breast and prostate cancer as representative examples. Future directions focusing on the direct detection of dysfunctional telomeres are explored. New markers for telomere dysfunction may eventually prove clinically useful.

Detection of telomerase activity in cultured cells and tumor tissue of lung carcinoma by modified telomeric repeat amplification protocol

Telomerase activity is found in various cell types including stem cells, neoplastic cells, and immortalized cells, suggesting a close association with their proliferation capacity. The telomeric repeat amplification protocol (TRAP) has been traditionally used to detect semi-quantitatively the telomerase activity by polyacrylamide gel electrophoresis (PAGE), which is difficult to apply for large scale analysis because of laborious post-PCR manipulation and potential carryover contamination. In the present study, a specific reverse primer was designed and the TRAP protocol was adapted to either PAGE or real-time PCR assay. Using cultured cell lines, the real-time TRAP showed a dramatic improvement in the reliability and accuracy of quantitation of telomerase activity and was able to discriminate the A549 cells from hundreds-fold human embryonic lung cells. Using clinical samples of 60 lung cancers and 8 inflammatory lesions, the real-time TRAP was also superior in quantitation, high-throughput capability and standardization. Our modified real-time TRAP should be applicable for the detection of telomerase activity for the initial screening and progression monitoring of lung cancer patients. Our approach is particularly useful when only limited clinical specimen is available, such as fine needle aspiration or other cytological specimens that may contain only a small number of tumor cells.

Telomerase as an important target of androgen signaling blockade for prostate cancer treatment

As the mainstay treatment for advanced prostate cancer, androgen deprivation therapy (ADT) targets the action of androgen receptor (AR) by reducing androgen level and/or by using anti-androgen to compete with androgens for binding to AR. Albeit effective in extending survival, ADT is associated with dose-limiting toxicity and the development of castration-resistant prostate cancer (CRPC) after prolonged use. Because CRPC is lethal and incurable, developing effective strategies to enhance the efficacy of ADT and circumvent resistance becomes an urgent task. Continuous AR signaling constitutes one major mechanism underlying the development of CRPC. The present study showed that methylseleninic acid (MSA), an agent that effectively reduces AR abundance, could enhance the cancer-killing efficacy of the anti-androgen bicalutamide in androgen-dependent and CRPC cells. We found that the combination of MSA and bicalutamide produced a robust downregulation of prostate-specific antigen and a recently identified AR target, telomerase, and its catalytic subunit, human telomerase reverse transcriptase. The downregulation of hTERT occurs mainly at the transcriptional level, and reduced AR occupancy of the promoter contributes to downregulation. Furthermore, apoptosis induction by the two agents is significantly mitigated by the restoration of hTERT. Our findings thus indicate that MSA in combination with anti-androgen could represent a viable approach to improve the therapeutic outcome of ADT. Given the critical role of hTERT/telomerase downregulation in mediating the combination effect and the fact that hTERT/telomerase could be measured in blood and urine, hTERT/telomerase could serve as an ideal tumor-specific biomarker to monitor the efficacy of the combination therapy noninvasively.

Markers for detection of prostate cancer

Early detection of prostate cancer is problematic, not just because of uncertainly whether a diagnosis will benefit an individual patient, but also as a result of the imprecise and invasive nature of establishing a diagnosis by biopsy. Despite its low sensitivity and specificity for identifying patients harbouring prostate cancer, serum prostate specific antigen (PSA) has become established as the most reliable and widely-used diagnostic marker for this condition. In its wake, many other markers have been described and evaluated. This review focuses on the supporting evidence for the most prominent of these for detection and also for predicting outcome in prostate cancer.

Urine biomarkers in prostate cancer

The deficiencies of serum PSA as a prostate-cancer-specific diagnostic test are well recognized. Thus, the development of novel biomarkers for prostate cancer detection remains an important and exciting challenge. Noninvasive urine-based tests are particularly attractive candidates for large-scale screening protocols, and biomarker discovery programs using urine samples have emerged for detecting and predicting aggressiveness of prostate cancer. Some new biomarkers already outperform serum PSA in the diagnosis of this disease. Currently, the PCA3 (prostate cancer antigen 3) urine test is probably the best adjunct to serum PSA for predicting biopsy outcome, and has proven its clinical relevance by surpassing the predictive abilities of traditional serum biomarkers. New research methods are also emerging, and high-throughput technologies will facilitate high-dimensional biomarker discovery. Future approaches will probably integrate proteomic, transcriptomic and multiplex approaches to detect novel biomarkers, and aim to identify combinations of multiple biomarkers to optimize the detection of prostate cancer. In addition, an unmet need remains for markers that differentiate indolent from aggressive cancers, to better inform treatment decisions.

Can urinary exosomes act as treatment response markers in prostate cancer?

BACKGROUND

Recently, nanometer sized vesicles (termed exosomes) have been described as a component of urine. Such vesicles may be a useful non-invasive source of markers in renal disease. Their utility as a source of markers in urological cancer remains unstudied. Our aim in this study was to investigate the feasibility and value of analysing urinary exosomes in prostate cancer patients undergoing standard therapy.

METHODS

Ten patients (with locally advanced PCa) provided spot urine specimens at three time points during standard therapy. Patients received 3-6 months neoadjuvant androgen deprivation therapy prior to radical radiotherapy, comprising a single phase delivering 55 Gy in 20 fractions to the prostate and 44 Gy in 20 fractions to the pelvic nodes. Patients were continued on adjuvant ADT according to clinical need. Exosomes were purified, and the phenotype compared to exosomes isolated from the prostate cancer cell line LNcaP. A control group of 10 healthy donors was included. Serum PSA was used as a surrogate treatment response marker. Exosomes present in urine were quantified, and expression of prostate markers (PSA and PSMA) and tumour-associated marker 5T4 was examined.

RESULTS

The quantity and quality of exosomes present in urine was highly variable, even though we handled all materials freshly and used methods optimized for obtaining highly pure exosomes. There was approx 2-fold decrease in urinary exosome content following 12 weeks ADT, but this was not sustained during radiotherapy. Nevertheless, PSA and PSMA were present in 20 of 24 PCa specimens, and not detected in healthy donor specimens. There was a clear treatment-related decrease in exosomal prostate markers in 1 (of 8) patient.

CONCLUSION

Evaluating urinary-exosomes remains difficult, given the variability of exosomes in urine specimens. Nevertheless, this approach holds promise as a non-invasive source of multiple markers of malignancy that could provide clinically useful information.

Human telomerase reverse transcriptase expression correlates with vascular endothelial growth factor-promoted tumor cell proliferation in prostate cancer

OBJECTIVE

To investigate the correlation between the expressions of human telomerase reverse transcriptase (hTERT) and vascular endothelial growth factor (VEGF) in prostate cancer (PCa) and benign prostatic hyperplasia (BPH), and to determine if hTERT was correlated with VEGF-promoted tumor cell proliferation in prostate cancer.

MATERIALS AND METHODS

Immunohistochemistry was used to analyze the expressions of hTERT and VEGF in 60 cases of PCa and 60 cases of benign prostatic hyperplasia (BPH). Then their correlation in PCa was analyzed by Spearman correlative analysis.

RESULTS

The expressions of hTERT were detected in 38 cases of PCa and 10 cases of BPH. The expressions of VEGF were detected in 46 cases of PCa and 28 cases of BPH. The expressions of hTERT and VEGF in PCa were significantly higher than those in BPH (P < 0.05). As a result of correlation analysis, it was found that with an increase of the expression of VEGF, the expression of hTERT also increased in PCa. Significant correlation was observed between the expressions of hTERT and VEGF in PCa (r = 0.8333, P < 0.05). But there was no significant correlation between the expressions of hTERT and VEGF in BPH (r = 0.3156, P > 0.05).

CONCLUSIONS

All experiences above indicate that hTERT was one of the important proteins in the proliferation-promoting effect of VEGF on tumor cells in PCa.

Clinical significance of telomerase activity in peritoneal disseminated cells: gastrointestinal cancers

Early detection and accurate staging of gastrointestinal (GI) cancers are difficult. The aim of this study was to evaluate whether telomerase activity (TA) in exfoliated/disseminated epithelial cells could be used as a reliable marker for GI cancers. TA was evaluated with the real-time RTQ-TRAP in immunomagnetically sorted peritoneal epithelial cells from 60 patients undergoing surgical treatment. Thirty-two patients were clinically diagnosed with a variety of GI cancers: 1 had premalignant disease, 2 had history of GI cancers, and 25 patients were clinically negative for cancer. Here we report that all types and all cases of gastrointestinal cancers were telomerase positive, thereby demonstrating 100% sensitivity for cancer. Eighteen of 25 nonmalignant cases had undetectable levels of TA, 2 had low, and 5 of 25 expressed high TA levels. Because normal epithelial cells usually have low TA and a lesser tendency to exfoliate compared with cancer cells, it is of great importance to have close follow-up for these patients to exclude possible malignant disease. We conclude that RTQ-TRAP assessment of TA in immunomagnetically sorted peritoneal epithelial cells has 100% sensitivity and 100% negative predictive value for GI cancers, and therefore, can be considered as a valuable tool and useful addition to current standard diagnostic methods. Clinical significance of unusually high telomerase activity in some clinically negative for cancer cases requires further study.

Molecular biomarkers for cancer detection in blood and bodily fluids

Cancer is a major and increasing public health problem worldwide. Traditionally, the diagnosis and staging of cancer, as well as the evaluation of response to therapy have been primarily based on morphology, with relatively few cancer biomarkers currently in use. Conventional biomarker studies have been focused on single genes or discrete pathways, but this approach has had limited success because of the complex and heterogeneous nature of many cancers. The completion of the human genome project and the development of new technologies have greatly facilitated the identification of biomarkers for assessment of cancer risk, early detection of primary cancers, monitoring cancer treatment, and detection of recurrence. This article reviews the various approaches used for development of such markers and describes markers of potential clinical interest in major types of cancer. Finally, we discuss the reasons why so few cancer biomarkers are currently available for clinical use.

Nucleic acid-based marker approaches to urologic cancers

There are numerous molecular modifications known to occur in cancer. New nucleic acid-based biomarkers provide a unique approach to patient management in urologic oncology. Malignant transformation of a normal cell requires a series of epigenetic and genetic changes or "hits." Epigenetics produced by deoxyribonucleic acid methylation, adding a methyl group to the fifth position of cytosine within CpG dinucleotides, are important players in deoxyribonucleic acid repair, genome instability, and regulation of chromatin structure. Genetic alterations in cancer can include mutations, chromosome deletions, insertions, amplifications, and translocations. In addition, the modifications of telomeres are critical to the maintenance of chromatin structure, transcription, and cell function in cancer. We review only nucleic acid-based molecular biomarkers in urologic oncology that can assist the clinician in establishing the diagnosis of disease, or that can predict the behavior of the disease or the patient's survival.

Urinary markers for prostate cancer

Prostate cancer is the commonest solid-organ malignancy to affect men in Europe and the USA; it is estimated that one in six men will develop this cancer in their lifetime. Current screening relies on a digital rectal examination with a serum prostate-specific antigen test. Novel urinary diagnostic tests are potentially interesting screening tools for this disease. We examined published reports assessing the use of urinary markers for the diagnosis of prostate cancer. Using a PubMed-based search we identified studies of urinary markers for prostate cancer published from 1985 to February 2006 using the search terms 'urine', 'marker' and 'prostate cancer'. Studies to date have used small cohorts and relied on prostatic biopsies to provide histology. The sensitivity and specificity of markers are wide ranging but with only a few studies published on each putative marker it is difficult to assess their potential impact. Using urinary biomarkers for prostate cancer is a relatively novel diagnostic approach; they are appealing as a screening test because they are not invasive. Further work is needed to identify and validate 'signature markers' indicative of prostatic malignancy. The newer proteomic platforms are promising biomarker discovery tools that might uncover the next generation of urinary biomarkers.

Molecular markers of prostate cancer

Although prostate-specific antigen (PSA) has evolved as a very useful tool for detection of prostate cancer, there remains an urgent need for more accurate biomarkers to diagnose prostate cancer and predict cancer-related outcomes. Recent advances in the study of proteomics and high throughput techniques have led to the discovery of many potential biomarkers for prostate cancer. This article briefly reviews the current status of PSA testing and discusses several candidate protein biomarkers for prostate cancer, as well as highlighting some recent proteomic discoveries with the potential to supplement or even replace PSA for the diagnosis and prognosis of prostate cancer.

Real-Time Quantification of Human Telomerase Reverse Transcriptase mRNA in the Plasma of Patients with Prostate Cancer

The aim of this study was to evaluate the potential diagnostic value of quantitative analysis of human telomerase reverse transcriptase (hTERT) mRNA in plasma for noninvasive diagnosis of prostate cancer (PCa). Expression levels of hTERT were analyzed by real-time quantitative RT-PCR in 68 patients showing elevated prostate-specific antigen (PSA) levels and a control group of 44 healthy volunteers. Sensitivity and specificity were determined and compared to the corresponding PSA values. Median values for hTERT gene expression in the PCa patients (0.72 ng; range 0.01-12.86) were statistically significantly higher (P < 0.001) than in the control group (0.13 ng; 0.02-0.35). Patients with clinically confirmed prostatitis showed lower plasma hTERT expression than PCa patients (0.29; 0.01-66.07). At a cutoff value of 0.35 sensitivity and specificity for the diagnosis of PCa were 81% and 60%, respectively. We suggest that hTERT mRNA in plasma is a very specific and sensitive method that may aid to differentiate between malignant and nonmalignant prostate tissue and may be a useful marker (in combination with PSA) for early PCa diagnosis.

Molecular markers in the diagnosis of prostate cancer

The genetic alterations leading to prostate cancer are gradually being discovered. A wide variety of genes have been associated with prostate cancer development as well as tumor progression. Knowledge of gene polymorphisms associated with disease aid in the understanding of important pathways involved in this process and may result in the near future in clinical applications. Urinary molecular markers will soon be available to aid in the decision of repeat prostate biopsies. Recent findings suggest the importance of androgen signaling in disease development and progression. The further understanding of interaction of inflammation, diet, and genetic predisposition will improve risk stratification in the near future.

Highly sensitive revealing of PCR products with capillary electrophoresis based on single photon detection

Post-PCR fragment analysis was conducted using our single photon detection-based DNA sequencing instrument in order to substantially enhance the detection of nucleic biomarkers. Telomerase Repeat Amplification Protocol assay was used as a model for real-time PCR-based amplification and detection of DNA. Using TRAPeze XL kit, telomerase-extended DNA fragments were obtained in extracts of serial 10-fold dilutions of telomerase-positive cells, then amplified and detected during 40-cycle real-time PCR. Subsequently, characteristic 6-base DNA ladder patterns were revealed in the post-PCR samples with capillary electrophoresis (CE). In our CE instrument, fluorescently labeled DNA fragments separate in a single-capillary module and are illuminated by a fiberized Ar-ion laser. The laser-induced fluorescence (LIF) is filtered and detected by the fiberized single photon detector (SPD). To assess the sensitivity of our instrument, we performed PCR at fewer cycles (29 and 25), so that the PCR machine could detect amplification only in the most concentrated samples, and then examined samples with CE. Indeed, PCR has detected amplification in samples with minimum 10(4) cells at 29 cycles and over 10(5) cells at 25 cycles. In contrast, the SPD-based CE-LIF has revealed 6-base repeats in samples with as low as 10(2) cells after 29 cycles and 10(3) cells after 25 cycles. Thus, we have demonstrated 100- to 1000-fold increase in the sensitivity of biomarker detection over real-time PCR, making our approach especially suitable for analysis of clinical samples where abundant PCR inhibitors often cause false-negative results.

Real-time telomerase assay of less-invasively collected esophageal cell samples

Genomic and proteomic efforts have discovered a complex list of biomarkers that identify human disease, stratify risk of disease within populations, and monitor drug or therapy responses for treatment. Attention is needed to characterize these biomarkers and to develop high-throughput technologies to evaluate their accuracy and precision. Telomerase activity is correlated with tumor progression, indicating cells that express telomerase possess aggressive clinical behavior and that telomerase activity could be a clinically important cancer biomarker. Traditionally, the detection of cancer has involved invasive procedures to procure samples. There is a need for less invasive approaches suitable for population- and clinic-based assays for cancer early detection. Esophageal balloon cytology (EBC) is a low-invasive screening technique, which samples superficial epithelial cells from the esophagus. Since telomerase activity is absent in superficial cells of normal esophageal squamous epithelium but is often present in superficial cells from dysplastic lesions and ESCCs, measuring telomerase activity in EBC samples may be a good way to screen for these lesions. The development of rapid real-time telomerase activity assays raises the possibility of extending such screening to high-risk populations. In this study, we evaluate the feasibility of using rapid Real-Time Telomerase Repeat Amplification Protocol (RTTRAP) for the analysis of NIST telomerase candidate reference material and esophageal clinical samples. The telomerase activity of eight EBC samples was also measured by capillary electrophoresis of RTTRAP products, RApidTRAP, and hTERT mRNA RT-PCR assays. These findings demonstrate the feasibility of using the RTTRAP assay in EBC samples and suggest that individuals from high-risk populations can be screened for telomerase activity.