Prostate cancer molecular markers GSTP1 and hTERT in expressed prostatic secretions as predictors of biopsy results

Role of glutathione-S-transferase gene P1 in the diagnosis of prostate cancer in patients with 'grey level' prostate-specific antigen values

Prostate cancer (PC) represents the second most frequent cancer diagnosis in men and, at the same time, is one of the top six causes of death worldwide. The aim of the present study was to evaluate the diagnostic value of glutathione-S-transferase gene P1 (GST-P1) in patients that fall within the 'grey area' of the prostate-specific antigen (PSA) values. A retrospective observational study on 80 patients with prostate abnormal volumes and PSA values in the range 4-10 ng/ml was performed. The prostate gland was extracted following transrectal ultrasonography, and GST-P1 gene expression was analysed. A histopathological examination was considered the gold standard for PC diagnosis. Among the 53 patients diagnosed with PC, 69.8% (n=37) were GST-P1-positive, whereas, among the 27 patients diagnosed with benign prostatic hyperplasia, 18.5% (n=5) were GST-P1-positive. The sensitivity for diagnosing PC in patients with PSA values between 4 and 10 ng/ml was 69.81%, and the specificity was 81.48%. The positive predictive value was 88.1% [95% confidence interval (CI), 74.37-96.02%] and the negative predictive value was 57.89% (95% CI, 40.82-73.69%). Collectively, these results show the potential of using GST-P1 gene expression in patients who are suspected of having PC, but where the PSA values are inconclusive.

hTERT, hTR and TERT promoter mutations as markers for urological cancers detection: A systematic review

The clinical relevance of telomerase subunits (human reverse transcriptase - hTERT, and human telomerase RNA - hTR) and TERT promotor mutations as biomarkers in genitourinary cancers was reviewed through the systematic analysis of the current literature. We performed a systematic literature search using 2 databases (Medline and Scopus) over the past 20 years. Primary outcomes were sensitivity and specificity of hTR, hTERT and TERT promoter mutations. Secondary outcomes were the biomarkers predictive values for tumor characteristics. Regarding bladder cancer, hTERT in urine showed high sensitivity (mean values: 55%-96%), and specificity (69%-100%): it correlated with bladder cancer grade and/or stage. hTR sensitivity ranged from 77% to 92%. With adapted cut-off, it demonstrated 72% to 89% specificity. TERT promoter mutation rate was up to 80% both in tissue and urine, resulting in 62%-92% sensitivity for primary tumors and 42% for relapse. Specificity ranged from 73% to 96%, no correlations with stage were observed. In prostate cancer, hTERT in tissue, prostate secretion and serum showed high sensitivity (97.9%, 36%, and 79.2%-97.5%, respectively) and specificity values (70%, 66%, 60%-100%). hTR showed very high sensitivity (88% in serum and 100% in tissue) although specificity values were highly variable depending on the series and techniques (0%-96.5%). In RCC, hTERT sensitivity on tissue ranged from 90 to 97%, specificity from 25 to 58%. There was an association of hTERT expression with tumor stage and grade. hTERT showed high accuracy in genitourinary cancers, while the value of hTR was more controversial. hTERT and TERT promotor mutations may have predictive value for bladder cancer and RCC staging and grading, while no such relationship was observed in CaP. Although telomerase subunits showed clinically relevant values in genitourinary cancers, developing fast and cost-effective methods is required before contemplating routine use.

The triple role of glutathione S-transferases in mammalian male fertility

Male idiopathic infertility accounts for 15-25% of reproductive failure. One of the factors that has been linked to this condition is oxidative stress (OS), defined as the imbalance between antioxidants and reactive oxygen species. Amongst the different factors that protect the cell against OS, the members of the glutathione S-transferase (GST) superfamily play an important role. Interestingly, reduction or lack of some GSTs has been associated to infertility in men. Therefore, and to clarify the relationship between GSTs and male fertility, the aim of this work is to describe the role that GSTs play in the male reproductive tract and in sperm physiology. To that end, the present review provides a novel perspective on the triple role of GSTs (detoxification, regulation of cell signalling and fertilisation), and reports their localisation in sperm, seminal plasma and the male reproductive tract. Furthermore, we also tackle the existing correlation between some GST classes and male fertility. Due to the considerable impact of GSTs in human pathology and their tight relationship with fertility, future research should address the specific role of these proteins in male fertility, which could result in new approaches for the diagnosis and/or treatment of male infertility.

Analysis of DNA methylation in cancer: location revisited

Changes in DNA methylation in cancer have been heralded as promising targets for the development of powerful diagnostic, prognostic, and predictive biomarkers. Despite the existence of more than 14,000 scientific publications describing DNA methylation-based biomarkers and their clinical associations in cancer, only 14 of these biomarkers have been translated into a commercially available clinical test. Methodological and experimental obstacles are both major causes of this disparity, but the genomic location of a DNA methylation-based biomarker is an intrinsic and essential property that also has an important and often overlooked role. Here, we examine the importance of the location of DNA methylation for the development of cancer biomarkers, and take a detailed look at the genomic location and other relevant characteristics of the various biomarkers with commercially available tests. We also emphasize the value of publicly available databases for the development of DNA methylation-based biomarkers and the importance of accurate reporting of the full methodological details of research findings.

Approaches to urinary detection of prostate cancer

Background:

Prostate cancer is the most common cancer in American men that ranges from low risk states amenable to active surveillance to high risk states that can be lethal especially if untreated. There is a critical need to develop relatively non-invasive and clinically useful methods for screening, detection, prognosis, disease monitoring, and prediction of treatment efficacy. In this review, we focus on important advances as well as future efforts needed to drive clinical innovation in this area of urine biomarker research for prostate cancer detection and prognostication.

Methods:

We provide a review of current literature on urinary biomarkers for prostate cancer. We evaluate the strengths and limitations of a variety of approaches that vary in sampling strategies and targets measured; discuss reported urine tests for prostate cancer with respect to their technical, analytical, and clinical parameters; and provide our perspectives on critical considerations in approaches to developing a urine-based test for prostate cancer.

Results:

There has been an extensive history of exploring urine as a source of biomarkers for prostate cancer that has resulted in a variety of urine tests that are in current clinical use. Importantly, at least three tests have demonstrated high sensitivity (~90%) and negative predictive value (~95%) for clinically significant tumors; however, there has not been widespread adoption of these tests.

Conclusions:

Conceptual and methodological advances in the field will help to drive the development of novel urinary tests that in turn may lead to a shift in the clinical paradigm for prostate cancer diagnosis and management.

Inactivation Efficacy of Nonthermal Plasma-Activated Solutions against Newcastle Disease Virus

In recent years, plasma-activated solutions (PASs) have made good progress in the disinfection of medical devices, tooth whitening, and fruit preservation. In this study, we investigated the inactivation efficacy of Newcastle disease virus by PASs. Water, 0.9% NaCl, and 0.3% H₂O₂ were excited by plasma to obtain the corresponding solutions PAS(H₂O), PAS(NaCl), and PAS(H₂O₂). The complete inactivation of virus after PAS treatment for 30 min was confirmed by the embryo lethality assay (ELA) and hemagglutination (HA) test. Scanning electron microscopy (SEM) results showed that the morphology of the viral particle changed under PAS treatments. The total protein concentration of virus decreased as measured by a Bradford protein assay due to PAS treatment. The nucleic acid integrity assay demonstrated that viral RNA degraded into smaller fragments. Moreover, the physicochemical properties of PASs, including the oxidation-reduction potential (ORP), electrical conductivity, and H₂O₂ concentration, and electron spin resonance spectra analysis indicated that reactive oxygen and nitrogen species play a major role in the virus inactivation. Therefore, the application of PASs, as an environmentally friendly method, would be a promising alternative strategy in poultry industries.IMPORTANCE Newcastle disease (ND), as an infectious viral disease of avian species, caused significant economic losses to domestic animal and poultry industries. The traditional chemical sanitizers, such as chlorine-based products, are associated with risks of by-product formation with carcinogenic effects and environmental pollution. On the basis of this, plasma-activated water as a green disinfection product is a promising alternative for applications in stock farming and sterilization in hospitals and public places. In this study, we explored the inactivation efficacy of different plasma-activated solutions (PASs) against ND virus (NDV) and the possible underlying mechanisms. Our results demonstrated that reactive oxygen and nitrogen species detected in PASs, including short-lived OH˙ and NO˙ and long-lived H₂O₂, changed the morphology, destroyed the RNA structure, and degraded the protein of the virus, consequently resulting in virus inactivation. These lay a foundation for the application of PASs to resolve the issues of public health and environmental sanitation.

Inactivation Efficacy of Nonthermal Plasma-Activated Solutions against Newcastle Disease Virus

In recent years, plasma-activated solutions (PASs) have made good progress in the disinfection of medical devices, tooth whitening, and fruit preservation. In this study, we investigated the inactivation efficacy of Newcastle disease virus by PASs. Water, 0.9% NaCl, and 0.3% H2O2 were excited by plasma to obtain the corresponding solutions PAS(H2O), PAS(NaCl), and PAS(H2O2). The complete inactivation of virus after PAS treatment for 30 min was confirmed by the embryo lethality assay (ELA) and hemagglutination (HA) test. Scanning electron microscopy (SEM) results showed that the morphology of the viral particle changed under PAS treatments. The total protein concentration of virus decreased as measured by a Bradford protein assay due to PAS treatment. The nucleic acid integrity assay demonstrated that viral RNA degraded into smaller fragments. Moreover, the physicochemical properties of PASs, including the oxidation-reduction potential (ORP), electrical conductivity, and H2O2 concentration, and electron spin resonance spectra analysis indicated that reactive oxygen and nitrogen species play a major role in the virus inactivation. Therefore, the application of PASs, as an environmentally friendly method, would be a promising alternative strategy in poultry industries.IMPORTANCE Newcastle disease (ND), as an infectious viral disease of avian species, caused significant economic losses to domestic animal and poultry industries. The traditional chemical sanitizers, such as chlorine-based products, are associated with risks of by-product formation with carcinogenic effects and environmental pollution. On the basis of this, plasma-activated water as a green disinfection product is a promising alternative for applications in stock farming and sterilization in hospitals and public places. In this study, we explored the inactivation efficacy of different plasma-activated solutions (PASs) against ND virus (NDV) and the possible underlying mechanisms. Our results demonstrated that reactive oxygen and nitrogen species detected in PASs, including short-lived OH˙ and NO˙ and long-lived H2O2, changed the morphology, destroyed the RNA structure, and degraded the protein of the virus, consequently resulting in virus inactivation. These lay a foundation for the application of PASs to resolve the issues of public health and environmental sanitation.

Helicobacter pylori outer inflammatory protein A (OipA) suppresses apoptosis of AGS gastric cells in vitro

Outer inflammatory protein A (OipA) is an important virulence factor associated with gastric cancer and ulcer development; however, the results have not been well established and turned out to be controversial. This study aims to elucidate the role of OipA in Helicobacter pylori infection using clinical strains harbouring oipA "on" and "off" motifs. Proteomics analysis was performed on AGS cell pre-infection and postinfection with H. pylori oipA "on" and "off" strains, using liquid chromatography/mass spectrometry. AGS apoptosis and cell cycle assays were performed. Moreover, expression of vacuolating cytotoxin A (VacA) was screened using Western blotting. AGS proteins that have been suggested previously to play a role or associated with gastric disease were down-regulated postinfection with oipA "off" strains comparing to oipA "on" strains. Furthermore, oipA "off" and ΔoipA cause higher level of AGS cells apoptosis and G0/G1 cell-cycle arrest than oipA "on" strains. Interestingly, deletion of oipA increased bacterial VacA production. The capability of H. pylori to induce apoptosis and suppress expression of proteins having roles in human disease in the absence of oipA suggests that strains not expressing OipA may be less virulent or may even be protective against carcinogenesis compared those expressing OipA. This potentially explains the higher incidence of gastric cancer in East Asia where oipA "on" strains predominates.

Urinary RNA-based biomarkers for prostate cancer detection

Prostate cancer (PCa) is the commonest malignancy in the male population worldwide. Serum prostate specific antigen (PSA) test is the most important biomarker for the detection, follow-up and therapeutic monitoring of PCa. Defects in PSA specificity have elicited research for new biomarkers to improve early diagnosis and avoid false-positive results. This review evaluates urinary RNA-based biomarkers. Urine is a versatile body fluid for non-invasive biomarker detection in case of urological malignancies. The importance of RNA-based biomarkers has been demonstrated by the current use of PCA3, a long non coding RNA biomarker already approved by the Food and Drugs Administration. Through the years, other urinary RNA biomarkers have been evaluated, including the well-known TMPRSS2:ERG transcript, as well as many messenger RNAs, long non coding RNAs and micro-RNA. Validation of a specific urinary RNA-based marker or an algorithm of different biomarkers levels as diagnostic markers for PCa could be useful to avoid unnecessary prostate biopsies.

The role of epigenetics in genetic and environmental epidemiology

Epidemiology is the branch of science that investigates the causes and distribution of disease in populations in order to provide preventative measures and promote human health. The fields of genetic and environmental epidemiology primarily seek to identify genetic and environmental risk factors for disease, respectively. Epigenetics is emerging as an important piece of molecular data to include in these studies because it can provide mechanistic insights into genetic and environmental risk factors for disease, identify potential intervention targets, provide biomarkers of exposure, illuminate gene-environment interactions and help localize disease-relevant genomic regions. Here, we describe the importance of including epigenetics in genetic and environmental epidemiology studies, provide a conceptual framework when considering epigenetic data in population-based studies and touch upon the many challenges that lie ahead.

The present and future of prostate cancer urine biomarkers

In order to successfully cure patients with prostate cancer (PCa), it is important to detect the disease at an early stage. The existing clinical biomarkers for PCa are not ideal, since they cannot specifically differentiate between those patients who should be treated immediately and those who should avoid over-treatment. Current screening techniques lack specificity, and a decisive diagnosis of PCa is based on prostate biopsy. Although PCa screening is widely utilized nowadays, two thirds of the biopsies performed are still unnecessary. Thus the discovery of non-invasive PCa biomarkers remains urgent. In recent years, the utilization of urine has emerged as an attractive option for the non-invasive detection of PCa. Moreover, a great improvement in high-throughput “omic” techniques has presented considerable opportunities for the identification of new biomarkers. Herein, we will review the most significant urine biomarkers described in recent years, as well as some future prospects in that field.

Expressed prostatic secretion biomarkers improve stratification of NCCN active surveillance candidates: performance of secretion capacity and TMPRSS2:ERG models

PURPOSE

Active surveillance is a viable patient option for prostate cancer provided that a clinical determination of low risk and presumably organ confined disease can be made. To standardize risk stratification schemes the NCCN (National Comprehensive Cancer Network®) provides guidelines for the active surveillance option. We determined the effectiveness of expressed prostatic secretion biomarkers for detecting occult risk factors in NCCN active surveillance candidates.

MATERIALS AND METHODS

Expressed prostatic secretion specimens were obtained before robot-assisted radical prostatectomy. Secretion capacity biomarkers, including total RNA and expressed prostatic secretion specimen volume, were measured by standard techniques. RNA expression biomarkers, including TXNRD1 mRNA, prostate specific antigen mRNA, TMPRSS2:ERG fusion mRNA and PCA3 mRNA, were measured by quantitative reverse-transcription polymerase chain reaction.

RESULTS

Of the 528 patients from whom expressed prostatic secretions were collected 216 were eligible for active surveillance under NCCN guidelines. Variable selection on logistic regression identified 2 models, including one featuring types III and VI TMPRSS2:ERG variants, and one featuring 2 secretion capacity biomarkers. Of the 2 high performing models the secretion capacity model was most effective for detecting cases in this group that were up-staged or up-staged plus upgraded. It decreased the risk of up-staging in patients with a negative test almost eightfold and decreased the risk of up-staging plus upgrading about fivefold while doubling the prevalence of up-staging in the positive test group.

CONCLUSIONS

Noninvasive expressed prostatic secretion testing may improve patient acceptance of active surveillance by dramatically reducing the presence of occult risk factors among those eligible for active surveillance under NCCN guidelines.

Controversies in using urine samples for Prostate Cancer detection: PSA and PCA3 expression analysis

PURPOSE

Prostate cancer (PCa) is one of the most commonly diagnosed malignancies in the world. Although PSA utilization as a serum marker has improved prostate cancer detection it still presents some limitations, mainly regarding its specificity. The expression of this marker, along with the detection of PCA3 mRNA in urine samples, has been suggested as a new approach for PCa detection. The goal of this work was to evaluate the efficacy of the urinary detection of PCA3 mRNA and PSA mRNA without performing the somewhat embarrassing prostate massage. It was also intended to optimize and implement a methodological protocol for this kind of sampling.

MATERIALS AND METHODS

Urine samples from 57 patients with suspected prostate disease were collected, without undergoing prostate massage. Increased serum PSA levels were confirmed by medical records review. RNA was extracted by different methods and a preamplification step was included in order to improve gene detection by Real-Time PCR.

RESULTS

An increase in RNA concentration with the use of TriPure Isolation Reagent. Despite this optimization, only 15.8% of the cases showed expression of PSA mRNA and only 3.8% of prostate cancer patients presented detectable levels of PCA3 mRNA. The use of a preamplification step revealed no improvement in the results obtained.

CONCLUSION

This work confirms that prostate massage is important before urine collection for gene expression analysis. Since PSA and PCA3 are prostate specific, it is necessary to promote the passage of cells from prostate to urinary tract, in order to detect these genetic markers in urine samples.

Biomarkers for the diagnosis of new and recurrent prostate cancer

Prostate cancer is the most prevalent cancer in men and can be managed effectively if diagnosed early and monitored. Currently, prostate-specific antigen testing in conjunction with a digital rectal exam has been utilized for screening at-risk men. However, the lack of specificity of prostate-specific antigen as a marker for prostate cancer combined with the asymptomatic and slow-growing nature of prostate tumors has resulted in many men being overdiagnosed and subjected to surgery or treatment with adverse side effects. The focus in the research community currently has been on discovering noninvasive surrogate markers such as proteins, circulating tumor cells and nucleic acids in the blood or urine of patients with prostate cancer. These markers, in combination with prostate-specific antigen, are providing promise that a personalized multiparametric approach to prostate cancer diagnosis and monitoring will aid in managing this disease.

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.

Measurement of GSTP1 promoter methylation in body fluids may complement PSA screening: a meta-analysis

BACKGROUND

Prostate-specific antigen (PSA) screening has low specificity. Assessment of methylation status in body fluids may complement PSA screening if the test has high specificity.

METHOD

The purpose of this study was to conduct a meta-analysis of the sensitivity and specificity for prostate cancer detection of glutathione-s-transferase-π (GSTP1) methylation in body fluids (plasma, serum, whole blood, urine, ejaculate, and prostatic secretions). We conducted a comprehensive literature search on Medline (Pubmed). We included studies if they met all four of the following criteria: (1) measurement of DNA methylation in body fluids; (2) a case-control or case-only design; (3) publication in an English journal; and (4) adult subjects. Reviewers conducted data extraction independently using a standardised protocol. Twenty-two studies were finally included in this paper. Primer sequences and methylation method in each study were summarised and evaluated using meta-analyses. This paper represents a unique cross-disciplinary approach to molecular epidemiology.

RESULTS

The pooled specificity of GSTP1 promoter methylation measured in plasma, serum, and urine samples from negative-biopsy controls was 0.89 (95% CI, 0.80-0.95). Stratified analyses consistently showed a high specificity across different sample types and methylation methods (include both primer sequences and location). The pooled sensitivity was 0.52 (95% CI, 0.40-0.64).

CONCLUSIONS

The pooled specificity of GSTP1 promoter methylation measures in plasma, serum, and urine was excellent and much higher than the specificity of PSA. The sensitivity of GSTP1 was modest, no higher than that of PSA. These results suggest that measurement of GSTP1 promoter methylation in plasma, serum, or urine samples may complement PSA screening for prostate cancer diagnosis.

Urine markers and prostate cancer

Prostate cancer (PCa) is globally the most common cancer in men, with an estimated prevalence of more than two million cases. Given the poor success rate in treating advanced PCa, intervention in early stages may reduce the progression of a small, localized carcinoma to a large metastatic lesion, thereby reducing disease-related deaths. Urine is readily available and can be used to detect either exfoliated cancer cells or secreted products. The major advantages of urine-based assays are their noninvasive character and ability to monitor PCa with heterogeneous foci. The aim of this review was to summarize the current evidence regarding performance characteristics of tests proposed for urine-based prostate cancer detection.

Urinary proteomics: ready for prime time in urological cancer diagnostics?

The impact of clinical proteomics on the diagnosis and treatment of urological malignancies is modest in comparison with the high expectations of the past. However, most available studies suffer from flawed clinical designs rather than from technical limitations. This article will briefly introduce the main technological approaches taken, their advantages and disadvantages and will highlight the different challenges associated with urinary proteome analysis. Furthermore, several examples of the successful application of urinary clinical proteomics in the field of prostate and bladder cancer will be introduced. These examples suggest careful validation of novel biomarkers, appropriate study designs using blinded cohorts enrolled from appropriate target populations and the standardization of techniques as key elements required for successful urinary proteomics studies. These prerequisites are essential for turning the old promise of a personalized medicine approach into a new reality to optimize patients’ preventive and therapeutic care.

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.

Biomarkers for prostate cancer detection

Since its approval by the US FDA in 1986, prostate-specific antigen (PSA) has been employed to monitor men with a diagnosis of prostate cancer. In 1994, PSA was approved for use in prostate cancer screening and has been employed worldwide. However, due to the limited specificity of PSA for the disease, novel biomarkers are needed for detecting prostate cancer and for determining which cancers need to be treated. This review will discuss the development of new biomarkers for prostate cancer detection and disease prognostication, focusing on recent progress and particular topical issues related to the development and validation of these new markers.

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.

Molecular biomarkers in prostate cancer

BACKGROUND

After more than two decades of clinical use, serum prostate-specific antigen (PSA) has increased the early diagnosis of prostate cancer, detecting the disease even when small volumes are present. Although stage migration of prostate cancer has occurred, PSA has well-known limitations, despite attempts at refinement and modification, such as the use of PSA velocity, which have been used to improve it. New biomarkers for prostate cancer have been discovered, with promising early results.

OBJECTIVE/METHODS

This article reviews the ubiquitous current literature on biomarkers in prostate cancer. A search using MEDLINE and EMBASE databases was performed and those articles reporting biomarkers in prostate cancer with clinically significant findings in terms of detection were analyzed. Immunohistochemical markers were not considered for this review.

RESULTS/CONCLUSION

Despite many markers being promising, no single marker has satisfied the criteria as a perfect candidate. Limited clinical use of IL-6, TGF-β1 and PCA3 has commenced, and further widespread availability of these tests is expected in the coming years. The future lies in artificial neural networks and panels of markers instead of individual assays. Although PSA has some well-known limitations, it is at present the best marker available for prostate cancer when used in conjunction with nomograms or risk calculators.

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.

Emerging Biomarkers for the Diagnosis and Prognosis of Prostate Cancer

Background: Early detection of prostate cancer (CaP), the most prevalent cancer and the second-leading cause of death in men, has proved difficult, and current detection methods are inadequate. Prostate-specific antigen (PSA) testing is a significant advance for early diagnosis of patients with CaP.

Content: PSA is produced almost exclusively in the prostate, and abnormalities of this organ are frequently associated with increased serum concentrations. Because of PSA’s lack of specificity for CaP, however, many patients undergo unnecessary biopsies or treatments for benign or latent tumors, respectively. Thus, a more specific method of CaP detection is required to augment or replace screening with PSA. The focus recently has been on creating cost-effective assays for circulating protein biomarkers in the blood, but because of the heterogeneity of CaP, it has become clear that this effort will be a formidable challenge. Each marker will require proper validation to ensure clinical utility. Although much work has been done on variations of the PSA test (i.e., velocity, density, free vs bound, proisoforms) with limited usefulness, there are many emerging markers at various stages of development that show some promise for CaP diagnosis. These markers include kallikrein-related peptidase 2 (KLK2), early prostate cancer antigen (EPCA), PCA3, hepsin, prostate stem cell antigen, and α-methylacyl-CoA racemase (AMACR). We review biomarkers under investigation for the early diagnosis and management of prostate cancer.

Summary: It is hoped that the use of panels of markers can improve CaP diagnosis and prognosis and help predict the therapeutic response in CaP patients.

Performance of a single assay for both type III and type VI TMPRSS2:ERG fusions in noninvasive prediction of prostate biopsy outcome

BACKGROUND

TMPRSS2:ERG fusions are promising prostate cancer biomarkers. Because they can occur in multiple forms in a single cancer specimen, we developed a quantitative PCR test that detects both type III and type VI TMPRSS2:ERG fusions. The assay is quantified from a standard curve determined with a plasmid-cloned type III TMPRSS2:ERG fusion target.

METHODS

We collected expressed prostatic secretion (EPS) under an institutional review board-approved, blinded, prospective study from 74 patients undergoing transrectal ultrasound-guided biopsy for prostate cancer. We compared the characteristic performance of the test for type III and type VI TMPRSS2:ERG fusions in predicting biopsy outcome and distinguishing between high and low Gleason scores with similar tests for the expression of PCA3 and DNA methylation levels of the APC, RARB, RASSF1, and GSTP1 genes. We used logistic regression to analyze the effects of multiple biomarkers in linear combinations.

RESULTS

Each test provided a significant improvement in characteristic performance over baseline digital rectal examination (DRE) plus serum prostate-specific antigen (PSA); however, the test for type III and type VI TMPRSS2:ERG fusions yielded the best performance in predicting biopsy outcome [area under the curve (AUC) 0.823, 95% CI 0.728-0.919, P < 0.001] and Gleason grade >7 (AUC 0.844, 95% CI 0.740-0.948, P < 0.001).

CONCLUSIONS

Although each test appears to have diagnostic value, PSA plus DRE plus type III and type VI TMPRSS2:ERG provided the best diagnostic performance in EPS specimens.

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.

Glutathione S-transferase Pi mediates proliferation of androgen-independent prostate cancer cells

Prostate cancers generally acquire an androgen-independent growth capacity with progression, resulting in resistance to antiandrogen therapy. Therefore, identification of the genes regulated through this process may be important for understanding the mechanisms of prostate carcinogenesis. We here utilized androgen-dependent/independent transplantable tumors, newly established with the 'transgenic rat adenocarcinoma in prostate' (TRAP) model, to analyze their gene expression using microarrays. Among the overexpressed genes in androgen-independent prostate cancers compared with the androgen-dependent tumors, glutathione S-transferase pi (GST-pi) was included. In line with this, human prostate cancer cell lines PC3 and DU145 (androgen independent) had higher expression of GST-pi compared with LNCaP (androgen dependent) as determined by semiquantitative reverse transcription-polymerase chain reaction analysis. To investigate the roles of GST-pi expression in androgen-independent human prostate cancers, GST-pi was knocked down by a small interfering RNA (siRNA), resulting in significant decrease of the proliferation rate in the androgen-independent PC3 cell line. In vivo, administration of GST-pi siRNA-atelocollagen complex decreased GST-pi protein expression, resulting in enhanced numbers of TdT mediated dUTP-biotin nick-end labering (TUNEL)-positive apoptotic cells. These findings suggest that GST-pi might play important roles in proliferation of androgen-independent human prostate cancer cells.

Proteomics cataloging analysis of human expressed prostatic secretions reveals rich source of biomarker candidates

Expressed prostatic secretions (EPS) contain proteins of prostate origin that may reflect the health status of the prostate and be used as diagnostic markers for prostate diseases including prostatitis, benign prostatic hyperplasia, and prostate cancer. Despite their importance and potential applications, a complete catalog of EPS proteins is not yet available. We, therefore, undertook a comprehensive analysis of the EPS proteome using 2-D micro-LC combined with MS/MS. Using stringent filtering criteria, we identified a list of 114 proteins with at least two unique-peptide hits and an additional 75 proteins with only a single unique-peptide hit. The proteins identified include kallikrein 2 (KLK2), KLK3 (prostate-specific antigen), KLK11, and nine cluster of differentiation (CD) molecules including CD10, CD13, CD14, CD26, CD66a, CD66c, CD 143, CD177, and CD224. To our knowledge, this list represents the first comprehensive characterization of the EPS proteome, and it provides a candidate biomarker list for targeted quantitative proteomics analysis using a multiple reaction monitoring (MRM) approach. To help prioritize candidate biomarkers, we constructed a protein-protein interaction network of the EPS proteins using Cytoscape (www.cytoscape.org), and overlaid the expression level changes from the Oncomine database onto the network.

The usefulness of the detection of GSTP1 methylation in urine as a biomarker in the diagnosis of prostate cancer

PURPOSE

Prostate cancer has a unique set of problems associated with its early detection and diagnosis that might be aided by the addition of molecular markers, such as DNA hypermethylation. DNA methylation is an important epigenetic mechanism of gene regulation that has a critical role in normal developmental processes. Aberrant DNA methylation is a hallmark of carcinogenesis and GSTP1 hypermethylation is the most common molecular alteration in human prostate cancer. To our knowledge the clinical usefulness of the detection of gene methylation is yet to be established.

MATERIALS AND METHODS

We evaluated GSTP1 hypermethylation in urine collected after prostatic massage and in core needle biopsies from 100 men referred for diagnostic biopsy.

RESULTS

Methylation of GSTP1 in urine specimens had 75% sensitivity and 98% specificity for prostate cancer. GSTP1 methylation in the biopsy had 88% specificity and 91% sensitivity. Interestingly we observed a higher frequency of GSTP1 methylation in the urine of men with stage III vs II disease (100% vs 20%, p = 0.05).

CONCLUSIONS

This study suggests that the detection of GSTP1 methylation in prediagnostic urine may improve the specificity of PSA and help distinguish men with prostate cancer from those with benign prostatic hyperplasia. This finding should be further explored in a larger, prospective screening trial.

The effects of cyclooxygenase-2 expression in prostate cancer cells: modulation of response to cytotoxic agents

Cyclooxygenase (COX)-2 has emerged as an exciting target for therapeutic intervention in the management of cancer. Immunohistochemistry studies have indicated higher expression of COX-2 in cancerous versus benign prostatic tissue. We have explored the role of COX-2 in prostate cancer in terms of attenuation of apoptosis and sensitivity to pharmacological agents, including COX-2 inhibitors. The human prostate cancer cell line LNCaP was stably transfected with COX-2 (LNCaPCOX-2) and compared with the empty vector control line (LNCaPneo). Chemosensitivity testing indicated no change in sensitivity to the cytotoxic effects of COX-2 inhibitors celecoxib or sulindac or VP16. However, LNCaPCOX-2 cells showed 3-fold resistance to carboplatin, which was partially reversed by coincubation with the phosphatidylinositol 3-kinase inhibitor wortmannin. Concomitant with reduced apoptotic response to cytotoxic agents, LNCaPCOX-2 cells expressed increased levels of survivin and Bcl-2 with enhanced activation of AKT. We also investigated the effects of celecoxib on expression levels of genes relevant to prostate cancer and drug resistance in our model system using quantitative polymerase chain reaction analysis. Celecoxib treatment resulted in highly significant increases in the mRNA expression of the smooth muscle component desmin, the detoxification enzyme glutathione S-transferase pi (GSTpi), and nonsteroidal anti-inflammatory response gene (NAG-1) in the LNCaPCOX-2 cell line compared with LNCaPneo cells. Significant decreases in survivin levels and increases in GSTpi and NAG-1 appeared to be COX-2-dependent effects because they were more pronounced in LNCaPCOX-2 cells. Our findings indicate both COX-2-dependent and -independent mechanisms attributable to celecoxib and support its utility in the management of prostate cancer.

Biomarkers for prostate cancer detection

PURPOSE

The limitations of prostate specific antigen as a biomarker for prostate cancer screening, characterized by low sensitivity for acceptable false-positive rates, are well known. New markers that differentiate indolent from aggressive cancers to decrease potential the over treatment of prostate cancer are needed. We reviewed current and potential biomarkers for prostate cancer detection.

MATERIALS AND METHODS

A literature search was performed to identify established and emerging biomarkers for prostate cancer detection. Recent suggested guidelines by the Early Detection Research Network for phases of biomarker studies were interpreted for use in prostate cancer and the existing status of marker studies were reviewed with respect to these phases of study.

RESULTS

Advances in high throughput bench research, including high dimensional genomic, proteomic and autoantibody signatures, have the potential to improve the operating characteristics of prostate specific antigen but they are undergoing reproducibility and multicenter validation studies. None of the prostate specific antigen derivatives or isoforms, such as prostate specific antigen density, velocity or percent complexed prostate specific antigen, improve operating characteristics enough to likely replace prostate specific antigen. Prostate stem cell antigen, alpha-methyl coenzyme-A racemase, PCA3, early prostate cancer antigen, human kallikrein 2 and hepsin are promising markers that are currently undergoing validation.

CONCLUSIONS

The process of discovering novel biomarkers to replace or augment the existing best marker, prostate specific antigen, requires standardized phases of evaluation and validation. Several biomarkers are currently on the cusp of initial validation studies.

Progensa PCA3 test for prostate cancer detection

Patients with an elevated serum total prostate-specific antigen value or abnormal digital rectal examination results are at risk of having prostate cancer and should undergo prostate needle biopsies. However, approximately 60% of them will have a negative prostate biopsy result. Therefore, further biopsies are recommended for young patients at risk of prostate cancer with a positive rate of 20-40%. Biomarkers are required in order to avoid unnecessary biopsies. The PCA3 gene product is specifically overexpressed in prostate tumor cells, and modern molecular biology techniques allow us to use a specific test for this gene in order to select patients who have a high risk of having prostate cancer. Literature reviews of the gene product, as well as the first clinical results of the Progensa PCA3 test, are presented.

Biomarkers for prostate cancer

Novel biomarkers for prostate cancer (PCa) are currently being assessed for utility in PCa diagnosis. This article aims to provide concise information on the current findings that impact prostate cancer research. Results of enzyme-linked immunosorbent assays (ELISA) for single biomarkers, quantitative polymerase chain reaction (PCR)-based assays for DNA/RNA markers will be reviewed in addition to high-throughput proteomic profiling of PCa specimens. The advantages/disadvantages of tissue, blood, urine or seminal plasma as sources for potential biomarkers are discussed emphasizing the consequences for PCa diagnosis. In summary, the majority of promising marker candidates available today needs further validation. Some of the identified markers have the potential to yield novel prognostic tools for PCa, provide novel insights into its pathophysiology, and contribute to the establishment of novel treatment strategies.

Gene methylation and early detection of genitourinary cancer: the road ahead

DNA methylation is a common mechanism of inactivation of tumour-suppressor and other cancer genes in neoplastic cells. The advantages of gene methylation as a target for the detection and diagnosis of cancer in biopsy specimens and non-invasive body fluids such as urine or blood has led to many studies of application in genitourinary cancer. Here, we consider the background, promise and status, challenges and future directions of gene methylation and its clinical utility for the early detection of genitourinary cancer. The challenges of, and strategies for, advancing gene-methylation-based detection are relevant to all types of cancer.

Molecular PCA3 diagnostics on prostatic fluid

BACKGROUND

The PCA3 test on urine can improve specificity in prostate cancer (PCa) diagnosis and could prevent unnecessary prostate biopsies. In this study, we evaluated the PCA3 test on prostatic fluid and compared this with the PCA3 test on urine in a clinical research setting.

METHODS

Prostatic fluid and urine samples from 67 men were collected following digital rectal examination (DRE). The sediments were analyzed using the quantitative APTIMA PCA3 test. The results were compared with prostate biopsy results.

RESULTS

Using a PCA3 score of 66 as a cut-off value, the test on prostatic fluid had 65% sensitivity for the detection of PCa, 82% specificity and a negative predictive value of 82%. At a cut-off value of 43, the test on urine had 61% sensitivity, 80% specificity and a negative predictive value of 80%.

CONCLUSIONS

The PCA3 test can be performed on both urine and prostatic fluid in the diagnosis of PCa with comparable results.

Glutathione S-transferase pi (GSTP1) hypermethylation in prostate cancer: review 2007

Prostatic carcinoma is characterised by the silencing of the pi-class glutathione S-transferase gene (GSTP1), which encodes a detoxifying enzyme. The silencing of GSTP1 results from aberrant methylation at the CpG island in the promoter-5' and occurs in the vast majority of cases of high-grade prostatic intraepithelial neoplasia (PIN) and prostate cancers. We review the potential novel role of GSTP1 and its related expression in prostate cancer. The loss of expression (silencing) of the GSTP1 gene is the most common (>90%) genetic alteration reported to date in prostate cancer. Quantitative methylation-specific PCR assays allow detection of GSTP1 methylation in prostate biopsies and may improve the sensitivity of cancer detection. Advances in the epigenetic characterisation of prostate cancer have enabled the development of DNA methylation assays that may soon be used in diagnostic testing of serum and tissue for prostate cancer. Inhibition of aberrant promoter methylation could theoretically prevent carcinogenesis.

Conference report and review: current status of biomarkers potentially associated with prostate cancer outcomes

PURPOSE

The use of prostate specific antigen screening to diagnose and monitor prostate cancer is associated with well-known shortcomings. A 2-day Prostate Cancer Biomarker Conference was convened to identify promising areas of research and focus efforts on the most critical needs.

MATERIALS AND METHODS

The conference provided a forum for the presentation and discussion of ongoing prostate cancer biomarker research. This meeting also sought to identify a range of critical issues in the development and validation of biomarkers, foster research collaboration between groups representing government, academic and industry initiatives, and coordinate efforts with planned and ongoing clinical trials.

RESULTS

Taken collectively the conference presentations offered various new technologies for biomarker discovery and pathological assessment of clinical disease as well as the promise of biomarkers for improving prostate cancer diagnosis and treatment decisions. However, research efforts focused on biomarker validation and implementation clearly lag behind those directed toward initial biomarker discovery. It is apparent that guidelines are desperately needed to ensure the consistency of sample collection across institutions.

CONCLUSIONS

Several ongoing and planned adjuvant prostate cancer trials will provide a tremendous opportunity for biological sample collection along with the potential to validate many biomarkers. Practicing urologists have an opportunity to have a critical role in the successful accrual of patients into these trials.

Recovery of bisulfite-converted genomic sequences in the methylation-sensitive QPCR

Many methods for the detection of genomic DNA methylation states have appeared. Currently, nearly all such methods employ bisulfite-mediated deamination of denatured DNA. While this treatment effectively deaminates cytosines to uracils, leaving most 5-methylcytosines intact, it also introduces abasic sites that generate a significant number of single-strand breaks in DNA. We have investigated the interplay of these two processes in order to determine their relative effects on the methylation-sensitive QPCR method. The extent of cleavage of the input DNA is significant and appears to be an increasing function of DNA concentration. Even so, the results suggest that only ∼10% of a 62-nt target will be lost due to degradation and targets up to 131 nt will suffer only a 20% loss. More significant losses were found to occur during the subsequent removal of bisulfite and desulfonation steps that appear to be the result of size selectivity associated with matrix binding and elution required prior to QPCR in the most commonly used protocols. For biospecimens yielding <1 μg of DNA, these findings suggest that bisulfite treatment, in current implementations of MS-QPCR, result in low recoveries that preclude reliable analysis of DNA methylation patterns regardless of target size.

COX-2 inhibition: a possible role in the management of prostate cancer?

There is mounting evidence to support a role for cyclooxygenase-2 (COX-2) inhibitors (coxibs) in the management of prostate cancer. This review considers the current evidence base for the use of coxibs in prostate cancer as well as their adverse event profile. A systematic literature review using the search terms 'cyclooxygenase', 'COX-2', 'coxibs', 'cardiovascular risk', and 'prostate cancer' was performed using Medline. Celecoxib appears safer in terms of cardiovascular toxicity than other coxibs, and this may relate to its lower selectivity for the COX-2 enzyme. This lower selectivity also provides rationale for its putative broader anti-cancer effects, via non-COX-2-dependent pathways that affect cell cycle regulation, angiogenesis, and hypoxic modulation. There are also interacting relationships between COX-2, chronic inflammation, and prostate cancer. There is much promise for the coxibs as anti-cancer agents. The future might be to pharmacologically adapt these agents to exert their COX-2 independent mechanisms of action while minimizing their COX-2-dependent adverse cardiovascular effects.

[Diffusion of genetic testing in oncology: what criteria for regulation?]

Does gene testing indicate a switch from an histopathological to a molecular approach of human diseases ? Disease management in oncology is already improved by gene testing, at least for some specific cancers. It is however necessary to distinguish the analysis of genes specific to the tumour which gives clues about the fate of the tumours, from those unique to the patients, which gives clues about the future of the person. For the latter so-called germline mutations, wide scale gene-default screening would put pressure on resource allocation from the health care systems of developed countries. Currently the cost of detecting of 700 genes in the whole French population would exceed the whole health budget of the country for the next 10 years. Even if we can anticipate a dramatic decrease in the unit cost of these genetic tests in the future, their diffusion should not be controlled exclusively by technological and market forces. In this paper, we propose to discuss four main parameters for regulating these genetic tests, using as an archetypal example their application to cancer prevention and treatment: (1) which specific cancer disease is targeted by the test (prevalence, incidence, likelihood of cure with current therapeutics, number of years of life potentially saved...); (2) what are the characteristics of the genes tested and which level of evidence is required about the predictive value of the test; (3) what are the size and characteristics of the population who will be offered the test, and (4) which process and public control are necessary before market approval of the test and reimbursement of related expenditures by health care insurance schemes.

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.

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.

Urine markers as possible tools for prostate cancer screening: review of performance characteristics and practicality

BACKGROUND

In recent years, an increasing number of urine-based tests have been proposed as potential screening tests for prostate cancer. The goal of this review was to summarize the current status of evidence regarding performance characteristics of the proposed tests and their practicality under screening conditions.

METHOD

Relevant articles published up to and including May 2005 were identified in the PubMed database. At least 10 cases and 10 controls had to be analyzed for a study to be included in the review. Data concerning the study population, performance characteristics, and the collection and processing of urine samples were extracted from the reviewed articles.

RESULTS

In all, 34 retrospective studies evaluating 21 different markers complied with the inclusion criteria. Most of the studies were rather small and included heterogeneous clinical study populations. Promising results were reported for a few markers in single studies, but they have often not been replicated in subsequent larger studies. Some of the more promising results were obtained with 24-h urines or with specimen-handling procedures that might be difficult to perform under screening conditions.

CONCLUSIONS

Larger studies with a prospective design are required to confirm promising findings regarding performance characteristics of some novel markers recently reported in mostly small studies. Future studies should also pay particular attention to the practicality of the markers under screening conditions.

Accurate quantification of DNA methylation using combined bisulfite restriction analysis coupled with the Agilent 2100 Bioanalyzer platform

DNA methylation is the best-studied epigenetic modification and describes the conversion of cytosine to 5-methylcytosine. The importance of this phenomenon is that aberrant promoter hypermethylation is a common occurrence in cancer and is frequently associated with gene silencing. Various techniques are currently available for the analysis of DNA methylation. However, accurate and reproducible quantification of DNA methylation remains challenging. In this report, we describe Bio-COBRA (combined bisulfite restriction analysis coupled with the Agilent 2100 Bioanalyzer platform), as a novel approach to quantitative DNA methylation analysis. The combination of a well-established method, COBRA, which interrogates DNA methylation via the restriction enzyme analysis of PCR-amplified bisulfite treated DNAs, with the Bioanalyzer platform allows for the rapid and quantitative assessment of DNA methylation patterns in large sample sets. The sensitivity and reproducibility of Bio-COBRA make it a valuable tool for the analysis of DNA methylation in clinical samples, which could aid in the development of diagnostic and prognostic parameters with respect to disease detection and management.