Detection of GSTP1 methylation in prostatic secretions using combinatorial MSP analysis

Antiproliferative, apoptosis-inducing, and GSTP1 demethylation activities of Ellagitannins isolated from Cornus alba L

This study aimed to prove the prostate cancer chemopreventive activity of compounds isolated from CA. We evaluated these compounds using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and evaluated their NF-κB inhibitory activity and apoptosis-inducing activity using western blot analysis and flow cytometry, respectively. Their DNA methylation activity was also evaluated via a methylation-specific polymerase chain reaction in androgen-dependent (LNCaP) and androgen-independent (PC-3) prostate cancer cell lines. Camptothin B (1), cornusiin B (2), and cornusiin A (3), which were isolated in our previous work, relatively reduced the protein expression levels in PCa cells. Among them, cornusiin B (2) exhibited excellent NF-κB inhibitory activity. Also, concentration-dependently increased the unmethylated DNA content and decreased the methylated DNA content in both PC-3 and LNCaP cells. Therefore, cornusiin B (2), which was isolated from CA, has the potential to act as a chemopreventive agent for prostate cancer.

Alnus sibirica Compounds Exhibiting Anti-Proliferative, Apoptosis-Inducing, and GSTP1 Demethylating Effects on Prostate Cancer Cells

Alnus sibirica (AS) is distributed in Korea, Japan, China, and Russia and has reported anti-oxidant, anti-inflammatory, and reducing activities on atopic dermatitis-like skin lesions, along with other beneficial health properties. In the present study, we tried to prove the cancer-preventive activity against prostate cancer. The extracted and isolated compounds, oregonin (1), hirsutenone (2), and hirsutanonol (3), which were isolated from AS, were tested for anti-proliferative activity. To do this, we used the MTT assay; NF-κB inhibitory activity, using Western blotting; apoptosis-inducing activity using flow cytometry; DNA methylation activity, using methylation-specific polymerase chain reaction in androgen-dependent (LNCaP) and androgen-independent (PC-3) prostate cancer cell lines. The compounds (1–3) showed potent anti-proliferative activity against both prostate cancer cell lines. Hirsutenone (2) exhibited the strongest NF-κB inhibitory and apoptosis-inducing activities compared with oregonin (1) and hirsutanonol (3). DNA methylation activity, which was assessed for hirsutenone (2), revealed a concentration-dependent enhancement of the unmethylated DNA content and a reduction in the methylated DNA content in both PC-3 and LNCaP cells. Overall, these findings suggest that hirsutenone (2), when isolated from AS, may be a potential agent for preventing the development or progression of prostate cancer.

Prostate Carcinogenesis: Insights in Relation to Epigenetics and Inflammation

Prostate cancer is a multifactorial disease that mainly occurs due to the accumulation of somatic, genetic, and epigenetic changes, resulting in the inactivation of tumor-suppressor genes and activation of oncogenes. Mutations in genes, specifically those that control cell growth and division or the repair of damaged DNA, make the cells grow and divide uncontrollably to form a tumor. The risk of developing prostate cancer depends upon the gene that has undergone the mutation. Identifying such genetic risk factors for prostate cancer poses a challenge for the researchers. Besides genetic mutations, many epigenetic alterations, including DNA methylation, histone modifications (methylation, acetylation, ubiquitylation, sumoylation, and phosphorylation) nucleosomal remodeling, and chromosomal looping, have significantly contributed to the onset of prostate cancer as well as the prognosis, diagnosis, and treatment of prostate cancer. Chronic inflammation also plays a major role in the onset and progression of human cancer, via modifications in the tumor microenvironment by initiating epithelialmesenchymal transition and remodeling the extracellular matrix. In this article, the authors present a brief history of the mechanisms and potential links between the genetic aberrations, epigenetic changes, inflammation, and inflammasomes that are known to contribute to the prognosis of prostate cancer. Furthermore, the authors examine and discuss the clinical potential of prostate carcinogenesis in relation to epigenetics and inflammation for its diagnosis and treatment..

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.

Genomic and Epigenomic Alterations in Cancer

Multiple genetic and epigenetic events characterize tumor progression and define the identity of the tumors. Advances in high-throughput technologies, like gene expression profiling, next-generation sequencing, proteomics, and metabolomics, have enabled detailed molecular characterization of various tumors. The integration and analyses of these high-throughput data have unraveled many novel molecular aberrations and network alterations in tumors. These molecular alterations include multiple cancer-driving mutations, gene fusions, amplification, deletion, and post-translational modifications, among others. Many of these genomic events are being used in cancer diagnosis, whereas others are therapeutically targeted with small-molecule inhibitors. Multiple genes/enzymes that play a role in DNA and histone modifications are also altered in various cancers, changing the epigenomic landscape during cancer initiation and progression. Apart from protein-coding genes, studies are uncovering the critical regulatory roles played by noncoding RNAs and noncoding regions of the genome during cancer progression. Many of these genomic and epigenetic events function in tandem to drive tumor development and metastasis. Concurrent advances in genome-modulating technologies, like gene silencing and genome editing, are providing ability to understand in detail the process of cancer initiation, progression, and signaling as well as opening up avenues for therapeutic targeting. In this review, we discuss some of the recent advances in cancer genomic and epigenomic research.

WOMEN IN CANCER THEMATIC REVIEW: Diverse functions of DNA methylation: implications for prostate cancer and beyond

Prostate cancer is one of the most common malignancies in men worldwide. Current clinical screening ensures that most prostate cancers are diagnosed while still organ confined, but disease outcome is highly variable. Thus, a better understanding of the molecular features contributing to prostate cancer aggressiveness is being sought. For many cancers, aberrant genome-wide patterns of cytosine DNA methylation in CpG dinucleotides distinguish tumor from normal tissue and contribute to disease progression by altering the transcriptome. In prostate cancer, recent genomic studies identified cancer and high grade-specific differential DNA methylation in gene promoters, gene bodies, gene 3' ends and at distal regulatory elements. Using examples from developmental and disease systems, we will discuss how DNA methylation in each of these genomic contexts can contribute to transcriptome diversity by modulating transcription initiation, alternative transcription start site selection, alternative pre-mRNA splicing and alternative polyadenylation. Alternative transcripts from the same gene often exhibit altered protein-coding potential, translatability, stability and/or localization. All of these can have functional consequences in cells. In future work, it will be important to determine if DNA methylation abnormalities in prostate cancer modify the transcriptome through some or all of these mechanisms and if these DNA methylation-mediated transcriptome alterations impact prostate tumorigenesis and aggressiveness.

Association between GSTP1 CpG methylation and the early phase of lead exposure

CONTEXT

GSTP1 is induced by lead, and thus serves as a biomarker of lead exposure. Lead exposure changes DNA methylation status.

OBJECTIVE

We attempted to prove that the methylation of the GSTP1 promoter plays an important role in lead toxicity.

MATERIALS AND METHODS

We conducted a case-control study of 53 workers from a battery plant and 53 age and sex matched healthy volunteers to determine whether the methylation level of the GSTP1 promoter is associated with the risk of lead poisoning. We employed methylation-specific PCR (MSP) in cell models to determine the relationship between the GSTP1 methylation level and lead exposure.

RESULTS

We found no association between GSTP1 methylation and lead exposure. The difference in methylation frequencies between the exposure group and the controls was not statistically significant (p = 0.401), and individuals with the methylated GSTP1 gene was not associated with the risk of lead poisoning (adjusted OR = 1.36, 95% CI, 0.22-8.24).

CONCLUSION

This study suggests that GSTP1 methylation is not involved in the early phase of lead toxicity. Further studies should be performed to detect the association between GSTP1 methylation and the risk of lead poisoning in later phases.

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.

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.

Aberrant DNA methylation and prostate cancer

Prostate cancer (PCa) is the most prevalent cancer, a significant contributor to morbidity and a leading cause of cancer-related death in men in Western industrialized countries. In contrast to genetic changes that vary among individual cases, somatic epigenetic alterations are early and highly consistent events. Epigenetics encompasses several different phenomena, such as DNA methylation, histone modifications, RNA interference, and genomic imprinting. Epigenetic processes regulate gene expression and can change malignancy-associated phenotypes such as growth, migration, invasion, or angiogenesis. Methylations of certain genes are associated with PCa progression. Compared to normal prostate tissues, several hypermethylated genes have also been identified in benign prostate hyperplasia, which suggests a role for aberrant methylation in this growth dysfunction. Global and gene-specific DNA methylation could be affected by environmental and dietary factors. Among other epigenetic changes, aberrant DNA methylation might have a great potential as diagnostic or prognostic marker for PCa and could be tested in tumor tissues and various body fluids (e.g., serum, urine). The DNA methylation markers are simple in nature, have high sensitivity, and could be detected either quantitatively or qualitatively. Availability of genome-wide screening methodologies also allows the identification of epigenetic signatures in high throughput population studies. Unlike irreversible genetic changes, epigenetic alterations are reversible and could be used for PCa targeted therapies.

DNA methylation based biomarkers: practical considerations and applications

A biomarker is a molecular target analyzed in a qualitative or quantitative manner to detect and diagnose the presence of a disease, to predict the outcome and the response to a specific treatment allowing personalized tailoring of patient management. Biomarkers can belong to different types of biochemical molecules such as proteins, DNA, RNA or lipids, whereby protein biomarkers have been the most extensively studied and used, notably in blood-based protein quantification tests or immunohistochemistry. The rise of interest in epigenetic mechanisms has allowed the identification of a new type of biomarker, DNA methylation, which is of great potential for many applications. This stable and heritable covalent modification mostly affects cytosines in the context of a CpG dinucleotide in humans. It can be detected and quantified by a number of technologies including genome-wide screening methods as well as locus- or gene-specific high-resolution analysis in different types of samples such as frozen tissues and FFPE samples, but also in body fluids such as urine, plasma, and serum obtained through non-invasive procedures. In some cases, DNA methylation based biomarkers have proven to be more specific and sensitive than commonly used protein biomarkers, which could clearly justify their use in clinics. However, very few of them are at the moment used in clinics and even less commercial tests are currently available. The objective of this review is to discuss the advantages of DNA methylation as a biomarker, the practical considerations for their development, and their use in disease detection, prediction of outcome or treatment response, through multiple examples mainly focusing on cancer, but also to evoke their potential for complex diseases and prenatal diagnostics.

Epigenetic markers of prostate cancer in plasma circulating DNA

Epigenetic differences are a common feature of many diseases, including cancer, and disease-associated changes have even been detected in bodily fluids. DNA modification studies in circulating DNA (cirDNA) may lead to the development of specific non-invasive biomarkers. To test this hypothesis, we investigated cirDNA modifications in prostate cancer patients with locally confined disease (n = 19), in patients with benign prostate hyperplasias (n = 20) and in men without any known prostate disease (n = 20). This initial discovery screen identified 39 disease-associated changes in cirDNA modification, and seven of these were validated using the sodium bisulfite-based mapping of modified cytosines in both the discovery cohort and an independent 38-patient validation cohort. In particular, we showed that the DNA modification of regions adjacent to the gene encoding ring finger protein 219 distinguished prostate cancer from benign hyperplasias with good sensitivity (61%) and specificity (71%). We also showed that repetitive sequences detected in this study were meaningful, as they indicated a highly statistically significant loss of DNA at the pericentromeric region of chromosome 10 in prostate cancer patients (p = 1.8 × 10(-6)). Based on these strong univariate results, we applied machine-learning techniques to develop a multi-locus biomarker that correctly distinguished prostate cancer samples from unaffected controls with 72% accuracy. Lastly, we used systems biology techniques to integrate our data with publicly available DNA modification and transcriptomic data from primary prostate tumors, thereby prioritizing genes for further studies. These data suggest that cirDNA epigenomics are promising source for non-invasive biomarkers.

DNA methylation of GSTP1 in human prostate tissues: pyrosequencing analysis

Purpose

DNA methylation is an important epigenetic mechanism of gene regulation and plays essential roles in tumor initiation and progression. Differences in methylation patterns between neoplastic and normal cells can be used to detect the presence of cancer. The aim of the present study was to evaluate the usefulness of glutathione-S-transferase-Pi (GSTP1) hypermethylation in discriminating between normal and prostate cancer (PCa) cells and in predicting tumor characteristics by use of quantitative pyrosequencing analysis.

Materials and Methods

A total of 100 human prostate tissues obtained from our institute were used in this study: 45 for benign prostatic hyperplasia (BPH) and 55 for PCa. The methylation level of GSTP1 was examined by a quantitative pyrosequencing analysis. The associations between GSTP1 methylation level and clinico-pathological parameter were also compared.

Results

The level of GSTP1 methylation was significantly higher in PCa samples than in BPH samples (56.7±32.7% vs. 1.6±2.2%, p<0.001). The sensitivity and specificity of GSTP1 methylation status in discriminating between PCa and BPH reached 85.5% and 100%, respectively. Even after stratification by stage, Gleason score, and prostate-specific antigen (PSA) level, similar results were obtained. A positive correlation between GSTP1 methylation level and serum PSA level was observed (r=0.303, p=0.002). There were no associations between GSTP1 methylation level and age, Gleason score, and staging.

Conclusions

Our study demonstrates that GSTP1 methylation is associated with the presence of PCa and PSA levels. This methylation marker is a potentially useful indicator for the detection and monitoring of PCa.

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.

Novel diagnostic biomarkers for prostate cancer

Prostate cancer is the most frequently diagnosed malignancy in American men, and a more aggressive form of the disease is particularly prevalent among African Americans. The therapeutic success rate for prostate cancer can be tremendously improved if the disease is diagnosed early. Thus, a successful therapy for this disease depends heavily on the clinical indicators (biomarkers) for early detection of the presence and progression of the disease, as well as the prediction after the clinical intervention. However, the current clinical biomarkers for prostate cancer are not ideal as there remains a lack of reliable biomarkers that can specifically distinguish between those patients who should be treated adequately to stop the aggressive form of the disease and those who should avoid overtreatment of the indolent form.

A biomarker is a characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. A biomarker reveals further information to presently existing clinical and pathological analysis. It facilitates screening and detecting the cancer, monitoring the progression of the disease, and predicting the prognosis and survival after clinical intervention. A biomarker can also be used to evaluate the process of drug development, and, optimally, to improve the efficacy and safety of cancer treatment by enabling physicians to tailor treatment for individual patients. The form of the prostate cancer biomarkers can vary from metabolites and chemical products present in body fluid to genes and proteins in the prostate tissues.

Current advances in molecular techniques have provided new tools facilitating the discovery of new biomarkers for prostate cancer. These emerging biomarkers will be beneficial and critical in developing new and clinically reliable indicators that will have a high specificity for the diagnosis and prognosis of prostate cancer. The purpose of this review is to examine the current status of prostate cancer biomarkers, with special emphasis on emerging markers, by evaluating their diagnostic and prognostic potentials. Both genes and proteins that reveal loss, mutation, or variation in expression between normal prostate and cancerous prostate tissues will be covered in this article. Along with the discovery of prostate cancer biomarkers, we will describe the criteria used when selecting potential biomarkers for further development towards clinical use. In addition, we will address how to appraise and validate candidate markers for prostate cancer and some relevant issues involved in these processes. We will also discuss the new concept of the biomarkers, existing challenges, and perspectives of biomarker development.

Oxidative stress and DNA methylation in prostate cancer

The protective effects of fruits, vegetables, and other foods on prostate cancer may be due to their antioxidant properties. An imbalance in the oxidative stress/antioxidant status is observed in prostate cancer patients. Genome oxidative damage in prostate cancer patients is associated with higher lipid peroxidation and lower antioxidant levels. Oxygen radicals are associated with different steps of carcinogenesis, including structural DNA damage, epigenetic changes, and protein and lipid alterations. Epigenetics affects genetic regulation, cellular differentiation, embryology, aging, cancer, and other diseases. DNA methylation is perhaps the most extensively studied epigenetic modification, which plays an important role in the regulation of gene expression and chromatin architecture, in association with histone modification and other chromatin-associated proteins. This review will provide a broad overview of the interplay of oxidative stress and DNA methylation, DNA methylation changes in regulation of gene expression, lifestyle changes for prostate cancer prevention, DNA methylation as biomarkers for prostate cancer, methods for detection of methylation, and clinical application of DNA methylation inhibitors for epigenetic therapy.

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.

Epigenetic alterations in human prostate cancers

Human prostate cancer cells carry a myriad of genome defects, including both genetic and epigenetic alterations. These changes, which can be maintained through mitosis, generate malignant phenotypes capable of selective growth, survival, invasion, and metastasis. During prostatic carcinogenesis, epigenetic changes arise earlier than genetic defects, linking the appearance of epigenetic alterations in some way to disease etiology. The most common genetic defect thus far described, leading to fusion transcripts between the androgen-regulated gene TMPRSS2 and genes from the ETS family of transcription factors, likely endows prostate cancer cells with the ability to co-opt androgen signaling, the major prostate differentiation pathway, to support the malignant phenotype. Whether epigenetic changes promote the appearance of TMPRSS2-ETS family fusion transcripts or collaborate with fusion transcript expression in the pathogenesis of prostate cancer has not been established. However, a growing list of epigenetic alterations has provided new opportunities for clinical tests that might aid in prostate cancer screening, detection, diagnosis, staging, and risk stratification. The epigenetic changes appear to be more attractive than genetic changes as prostate cancer biomarkers because epigenetic alterations are present in a greater fraction of prostate cancer cases than any of the known genetic defects. In addition, an emerging generation of assay strategies for detection of specific DNA sequences carrying (5-me)C, the major epigenetic genome mark, has pushed somatic epigenetic alterations to the forefront of molecular biomarker assay development for cancer. Finally, a growing portfolio of epigenetic drugs, capable of reversing the phenotypic consequences of somatic epigenetic defects, has entered clinical trials for prostate cancer in the search for a new rational therapy for the disease.

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.

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.

Development of a multiplexed urine assay for prostate cancer diagnosis

BACKGROUND

Several studies have demonstrated the value of DNA methylation in urine-based assays for prostate cancer diagnosis. However, a multicenter validation with a clinical prototype has not been published.

METHODS

We developed a multiplexed, quantitative methylation-specific polymerase chain reaction (MSP) assay consisting of 3 methylation markers, GSTP1, RARB, and APC, and an endogenous control, ACTB, in a closed-tube, homogeneous assay format. We tested this format with urine samples collected after digital rectal examination from 234 patients with prostate-specific antigen (PSA) concentrations > or =2.5 microg/L in 2 independent patient cohorts from 9 clinical sites.

RESULTS

In the first cohort of 121 patients, we demonstrated 55% sensitivity and 80% specificity, with area under the curve (AUC) 0.69. In the second independent cohort of 113 patients, we found a comparable sensitivity of 53% and specificity of 76% (AUC 0.65). In the first cohort, as well as in a combined cohort, the MSP assay in conjunction with total PSA, digital rectal examination status, and age improved the AUC without MSP, although the difference was not statistically significant. Importantly, the GSTP1 cycle threshold value demonstrated a good correlation (R = 0.84) with the number of cores found to contain prostate cancer or premalignant lesions on biopsy. Moreover, samples that exhibited methylation for either GSTP1 or RARB typically contained higher tumor volumes at prostatectomy than those samples that did not exhibit methylation.

CONCLUSIONS

These data confirm and extend previously reported studies and demonstrate the performance of a clinical prototype assay that should aid urologists in identifying men who should undergo biopsy.

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.

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.

Genetic and epigenetic biomarkers in cancer : improving diagnosis, risk assessment, and disease stratification

Gene expression patterns change during the initiation, progression, and development of cancer, as a result of both genetic and epigenetic mechanisms. Genetic changes arise due to irreversible changes in the nucleotide sequence, whereas epigenetic changes occur due to changes in chromatin conformation, histone acetylation, and methylation of the CpG islands located primarily in the promoter region of a gene. Both genetic and epigenetic markers can potentially be utilized to identify different stages of tumor development. Several such markers exhibit high sensitivity and specificity for different tumor types and can be assayed in biofluids and other specimens collected by noninvasive technologies. In spite of the availability of large numbers of diagnostic markers, only a few have been clinically validated so far. The current status and the challenges in the field of genetic and epigenetic markers in cancer diagnosis, risk assessment, and disease stratification are discussed.

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.

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.

Optimierte Standards der Prostatastanzbiopsie

As individual risk assessment mainly depends on the correct prediction of the tumor's biological behavior, primary diagnosis plays a key role in the clinical management of prostate cancer patients. Prostate core needle biopsy, as a primary diagnostic tool, should not only confirm clinical suspicion but also supply the urologist with information which is necessary for risk-adapted therapy. The experience and competence of both the urologist and the pathologist are crucial for the quality of prostate core needle biopsy diagnosis. Optimized handling and submission of prostate core needle biopsy specimens by the urologist to the pathologist are of outstanding importance for improving the number of cancer cases detected. Increasing availability of molecular markers leads to the necessity of developing new tissue sampling procedures which allow prostate core needle biopsy specimens to be simultaneously studied histologically and by molecular approaches.

Prospective diagnostic efficiency of biopsy washing DNA GSTP1 island hypermethylation for detection of adenocarcinoma of the prostate

BACKGROUND

The prospective diagnostic efficiency of quantitative glutathione S transferase (GSTP1) promoter hypermethylation analysis in biopsy washing samples has not been determined so far.

METHODS

Biopsies were obtained prospectively from 86 patients suspicious for prostate cancer (CaP). After isolation of DNA from biopsy washings and bisulfite conversion methylated and unmethylated GSTP1 sequences were specifically quantitated by real-time fluorescence PCR. Relative degrees of methylation were compared to results of histopathological examination.

RESULTS

Increased relative methylation was found for the CaP group (mean 28.1%) compared to biopsies without histological evidence for malignancy (5.2%; P < 0.001). A sensitivity and specificity of 92% and 86% and positive and negative predictive values of 82% and 94% were obtained. Receiver operating characteristic (ROC) analysis demonstrated a value of 0.90 (95% CI 0.82-0.98) for the area under curve (AUC).

CONCLUSIONS

Biopsy washing DNA GSTP1 hypermethylation analysis demonstrates a high diagnostic efficacy which is comparable to the retrospective analysis of biopsy tissue specimens. Moreover it is compatible with routine biopsy examination thus permitting further prospective evaluation in CaP diagnosis.

The expanding role of epigenetics in the development, diagnosis and treatment of prostate cancer and benign prostatic hyperplasia

PURPOSE

Prostate cancer research has focused significant attention on the mutation, deletion or amplification of the DNA base sequence that encodes critical growth or suppressor genes. However, these changes have left significant gaps in our understanding of the development and progression of disease. It has become clear that epigenetic changes or modifications that influence phenotype without altering the genotype present a new and entirely different mechanism for gene regulation. Several interrelated epigenetic modifications that are altered in abnormal growth states are DNA methylation changes, histone modifications and genomic imprinting. We discuss the status of epigenetic alterations in prostate cancer and benign prostatic hyperplasia progression. In addition, the rationale and status of ongoing clinical trials altering epigenetic processes in urological diseases are reviewed.

MATERIALS AND METHODS

An online search of current and past peer reviewed literature on DNA methylation, histone acetylation and methylation, imprinting and epigenetics in prostate cancer and benign prostatic hyperplasia was performed. Relevant articles and reviews were examined and a synopsis of reproducible data was generated with the goal of informing the practicing urologist of these advances and their implications.

RESULTS

Only 20 years ago the first study was published demonstrating global changes in DNA methylation patterns in tumors. Accumulating data have now identified specific genes that are commonly hypermethylated and inactivated during prostate cancer progression, including GSTpi, APC, MDR1, GPX3 and 14-3-3sigma. Altered histone modifications, including acetylation and methylation, were also recently described that may modify gene function, including androgen receptor function. These epigenetic changes are now being used to assist in prostate cancer diagnosis and cancer outcome prediction. Epigenetic changes appear to have a role in benign prostatic hyperplasia development as well as in the susceptibility of the prostate to developing cancer. Treatments involving 5-aza-deoxycytosine and other, more selective DNA methyltransferase inhibitors remove methyl residues from silenced genes, generating re-expression, and are currently being used in therapeutic trials. Histone deacetylase inhibitors have shown promise, not only by directly reactivating silenced genes, but also as regulators of apoptosis and sensitizers to radiation therapy.

CONCLUSIONS

Evolving data support a significant role for epigenetic processes in the development of prostate cancer and benign prostatic hyperplasia. Epigenetic changes can predict tumor behavior and often distinguish between genetically identical tumors. Targeted drugs that alter epigenetic modifications hold promise as a tool for curing and preventing these diseases.

High Concordance of Gene Methylation in Post-Digital Rectal Examination and Post-Biopsy Urine Samples for Prostate Cancer Detection

PURPOSE

We evaluated the concordance between post-digital rectal examination and post-prostate biopsy urine samples using conventional methylation specific polymerase chain reaction analysis of 3 gene promoters in patients with suspected or confirmed prostate cancer.

MATERIALS AND METHODS

Voided urine specimens were collected from 17 men after 15-second digital rectal examination and again after transrectal ultrasound guided biopsy of the prostate for suspected malignancy or for followup biopsy as part of an expectant management protocol. Urine sediment DNA was isolated and subjected to bisulfite modification. Methylation of GSTP1, EDNRB and APC promoters was determined by conventional methylation specific polymerase chain reaction analysis in post-digital rectal examination and post-biopsy samples, and correlated with clinical information.

RESULTS

Prostate cancer was detected on prostate biopsy in 12 of 17 patients (71%). Promoter methylation was detected in post-digital rectal examination urine specimens for GSTP1 (24%), APC (12%) and EDNRB (66%). Promoter methylation was detected in post-biopsy urine specimens for GSTP1 (18%), APC (18%) and EDNRB (77%). The concordance between post-digital rectal examination and post-biopsy urine samples was 94% for GSTP1 and APC, and 82% for EDNRB. Overall 100% of patients with biopsy proven prostate cancer had at least 1 gene methylated in urine vs 60% of those without evidence of prostate cancer on biopsy.

CONCLUSIONS

Gene analysis using conventional methylation specific polymerase chain reaction is a reliable method for detecting abnormal DNA methylation in voided urine samples obtained following digital rectal examination or prostate needle biopsy. The concordance between post-digital rectal examination and post-biopsy urinary samples for promoter methylation is high (82% to 94%), suggesting that urine collected after digital rectal examination may be used for genetic analysis with results similar to those in post-biopsy urine samples.

[Randomized controlled trial on haiguiyuyang capsule in the treatment of duodenal ulcer]

OBJECTIVE

To assess the efficacy and safety of haiguiyuyang capsule in the treatment of duodenal ulcer (also diagnosed as weiwan pain and hanrecuoza syndrome according to the theory of TCM).

METHODS

This is a multi-center clinical trial cooperatively conducted from May 2003 to March 2004 in accordance to the principle of informed consent, to the criteria for subject inclusion, exclusion, discontinuation, and to the relevant guidelines for evaluating the therapeutic effects of new TCM drugs. The design of double-blind, double-dummy and randomized controlled trial was adopted. 438 patients were randomized to the Test group (n = 330, treated with haiguiyuyang capsule) and to the Control group (n = 108, treated with ranitidine). The therapeutic course for both groups was 6 weeks.

RESULTS

Regarding the efficacy in treating duodenal ulcer, in the Test group, the Marked Efficacy Rate was 66.37% and the Total Efficacy Rate was 82.13%; in the Control group, the Marked Efficacy Rate was 68.61% and the Total Efficacy Rate was 93.34%; there was no significant difference between the two groups (P>0.05). Regarding the efficacy in treating the syndrome diagnosed by TCM, in the Test group, the Marked Efficacy Rate was 70.31% and the Total Efficacy Rate was 93.34%; in the control group, the rates were 71.29% and 91.66% respectively; there was no significant difference between the two groups (P>0.05). Besides, regarding the abatement of distention and fullness of stomach after treatment, the haiguiyuyang capsule was better than ranitidine (P<0.05). No adverse side-effect was observed.

CONCLUSION

The efficacy of haiguiyuyang capsule in treating duodenal ulcer is similar to that of ranitidine. No obvious adverse effect of it was observed in this trial.

Multigene Methylation Analysis for Detection and Staging of Prostate Cancer

PURPOSE

Aberrant gene promoter methylation profiles have been well-studied in human prostate cancer. Therefore, we rationalize that multigene methylation analysis could be useful as a diagnostic biomarker. We hypothesize that a new method of multigene methylation analysis could be a good diagnostic and staging biomarker for prostate cancer.

EXPERIMENTAL DESIGN

To test our hypothesis, prostate cancer samples (170) and benign prostatic hyperplasia samples (69) were examined by methylation-specific PCR for three genes: adenomatous polyposis coli (APC), glutathione S-transferase pi (GSTP1), and multidrug resistance 1 (MDR1). The methylation status of representative samples was confirmed by bisulfite DNA sequencing analysis. We further investigated whether methylation score (M score) can be used as a diagnostic and staging biomarker for prostate cancer. The M score of each sample was calculated as the sum of the corresponding log hazard ratio coefficients derived from multivariate logistic regression analysis of methylation status of various genes for benign prostatic hyperplasia and prostate cancer. The optimal sensitivity and specificity of the M score for diagnosis and for staging of prostate cancer was determined by receiver-operator characteristic (ROC) curve analysis. A pairwise comparison was employed to test for significance using the area under the ROC curve analysis. For each clinicopathologic finding, the association with prostate-specific antigen (PSA) failure-free probability was determined using Kaplan-Meier curves and a log-rank test was used to determine significance. The relationship between M score and clinicopathologic findings was analyzed by either the Mann-Whitney U test, Kruskal-Wallis test, or the Spearman rank correlation test.

RESULTS

The frequency of positive methylation-specific PCR bands for APC, GSTP1, and MDR1 genes in prostate cancer samples was 64.1%, 54.0%, and 55.3%, respectively. In benign prostatic hyperplasia samples, it was 8.7%, 5.8%, and 11.6%, respectively. There was a significant correlation of M score with high pT category (P < 0.001), high Gleason sum (P < 0.001), high preoperative PSA (P = 0.027), and advanced pathologic features. For all patients, the M score had a sensitivity of 75.9% and a specificity of 84.1% as a diagnostic biomarker using a cutoff value of 1.0. In patients with low or borderline PSA levels (<10.0 ng/mL), the M score was significantly higher in prostate cancers than in benign prostatic hyperplasias (2.635 +/- 0.200 and 0.357 +/- 0.121, respectively). ROC curve analysis revealed that the M score had a sensitivity of 65.4% and a specificity of 94.2% when 1.0 was used as a cutoff value. For all patients, M score can distinguish organ-confined (< or =pT(2)) from locally advanced cancer (> or =pT(3)) with a sensitivity of 72.1% and a specificity of 67.8%. Moreover, considering patients with PSA levels of <10 ng/mL, the M score has a sensitivity of 67.1% and a specificity of 85.7%. The ROC curve analysis showed a significant difference between M score and PSA (P = 0.010).

CONCLUSIONS

This is the first report demonstrating that M score is a new method for multigene methylation analysis that can serve as a good diagnostic and staging biomarker for prostate cancer.

Ethnic group-related differences in CpG hypermethylation of the GSTP1 gene promoter among African-American, Caucasian and Asian patients with prostate cancer

The incidence and mortality of prostate cancer (PC) is approximately 2-fold higher among African-Americans as compared to Caucasians and very low in Asian. We hypothesize that inactivation of GSTP1 genes through CpG methylation plays a role in the pathogenesis of PC, and its ability to serve as a diagnostic marker that differs among ethnic groups. GSTP1 promoter hypermethylation and its correlation with clinico-pathological findings were evaluated in 291 PC (Asian = 170; African-American = 44; Caucasian = 77) and 172 benign prostate hypertrophy samples (BPH) (Asian = 96; African-American = 38; Caucasian = 38) using methylation-specific PCR. In PC cells, 5-aza-dC treatment increased expression of GSTP1 mRNA transcripts. The methylation of all CpG sites was found in 191 of 291 PC (65.6%), but only in 34 of 139 BPH (24.5%). The GSTP1 hypermethylation was significantly higher in PC as compared to BPH in each ethnic group (p < 0.0001). Logistic regression analysis (PC vs. BPH) showed that African-Americans had a higher hazard ratio (HR) (13.361) compared to Caucasians (3.829) and Asian (8.603). Chi-square analysis showed correlation of GSTP1 hypermethylation with pathological findings (pT categories and higher Gleason sum) in Asian PC (p < 0.0001) but not in African-Americans and Caucasian PC. Our results suggest that GSTP1 hypermethylation is a sensitive biomarker in African-Americans as compared to that in Caucasians or Asian, and that it strongly influences tumor progression in Asian PC. Ours is the first study investigating GSTP1 methylation differences in PC among African-American, Caucasian and Asian.

Hypermethylation of the CpG islands in the promoter region of the GSTP1 gene in prostate cancer: a useful diagnostic and prognostic marker?

BACKGROUND

Recently, many studies have focused on the potential diagnostic value of the promoter hypermethylation of the GSTP1 gene in prostate cancer.

METHOD

A total of 144 patients, undergoing eight-core prostatic biopsies for a clinically suspected prostate cancer, was analyzed. Two different tissue samples were collected from the same area of the prostate and then divided for both genomic DNA extraction and pathological examination. In order to perform molecular analysis, prostatic tissue samples were digested with the methylation-sensitive restriction enzyme HpaII and then amplified by conventional polymerase chain reaction (PCR).

RESULTS

Prostate cancer was diagnosed in 42/144 patients, and promoter hypermethylation of GSTP1 gene was detected in 31/42 of prostate cancer (sensitivity=74%) and in 2/102 of negative specimens (specificity=98%). A significant association between GSTP1 promoter hypermethylation both with a Gleason score >or=7 (Fisher's exact P=0.01) and the presence of Gleason grade 4 and/or grade 5 (Fisher's exact P=0.03) was found.

CONCLUSION

Promoter hypermethylation of the GSTP1 gene is a highly specific--but not a very sensitive--marker of prostate cancer. Our data showed a significant association between the methylation status of the GSTP1 gene and Gleason score and grade, suggesting a potential prognostic value of this epigenetic DNA alteration.

Epigenetics and cancer

Both genetics and epigenetics regulate gene expression in cancer. Regulation by genetics involves a change in the DNA sequence, whereas epigenetic regulation involves alteration in chromatin structure and methylation of the promoter region. During the initiation, development, and progression of cancer, a number of genes undergo epigenetic changes. Some of these changes can be used as biomarkers for early detection of cancer as well as to follow treatment. A panel of epigenetic biomarkers is preferred to a single biomarker in clinical assays. Changes in gene expression due to epigenetic regulation can be reversed by chemicals, and this approach opens up a novel approach in cancer prevention and treatment.

Molecular biomarker in prostate cancer: the role of CpG island hypermethylation

CpG island hypermethylation may be one of the earliest somatic genome alterations to occur during the development of multiple cancers. Recently, aberrant methylation patterns for different tumors have been reported. We present a comprehensive review of the literature describing the role of CpG island hypermethylation of DNA from prostatic tissue and bodily fluids from men with prostate cancer. We reviewed the literature to evaluate CpG island hypermethylation in tissue and bodily fluids of men with primary and metastatic prostate cancer. Additionally, we reviewed the literature with respect to CpG island hypermethylation patterns in other urological malignancies. Using modern analytic methods, CpG island hypermethylation detection can be achieved. In men with prostate cancer, correlations between specific gene regulatory region hypermethylation analyses and Gleason score, pathologic stage and tumor recurrence have been demonstrated. CpG island hypermethylation may serve as a useful molecular biomarker for the detection and diagnosis of patients with prostate cancer.

Epigenetic changes in prostate cancer: implication for diagnosis and treatment

Prostate cancer is the most common noncutaneous malignancy and the second leading cause of cancer death among men in the United States. DNA methylation and histone modifications are important epigenetic mechanisms of gene regulation and play essential roles both independently and cooperatively in tumor initiation and progression. Aberrant epigenetic events such as DNA hypo- and hypermethylation and altered histone acetylation have both been observed in prostate cancer, in which they affect a large number of genes. Although the list of aberrantly epigenetically regulated genes continues to grow, only a few genes have, so far, given promising results as potential tumor biomarkers for early diagnosis and risk assessment of prostate cancer. Thus, large-scale screening of aberrant epigenetic events such as DNA hypermethylation is needed to identify prostate cancer-specific epigenetic fingerprints. The reversibility of epigenetic aberrations has made them attractive targets for cancer treatment with modulators that demethylate DNA and inhibit histone deacetylases, leading to reactivation of silenced genes. More studies into the mechanism and consequence of demethylation are required before the cancer epigenome can be safely manipulated with therapeutics as a treatment modality. In this review, we examine the current literature on epigenetic changes in prostate cancer and discuss the clinical potential of cancer epigenetics for the diagnosis and treatment of this disease.