Molecular forms of prostate-specific antigen and human kallikrein 2 (hK2) in urine are not clinically useful for early detection and staging of prostate cancer

Interfacial Polymerization Produced Magnetic Particles with Nano-Filopodia for Highly Accurate Liquid Biopsy in the PSA Gray Zone

Magnetic particles are leading separation materials for biological purification and detection. Existing magnetic particles, which almost rely on molecule-level interactions, however, often encounter bottlenecks in highly efficient cell-level separation due to the underestimate of surface structure effects. Here, immune cell-inspired magnetic particles with nano-filopodia (NFMPs) produced by interfacial polymerization for highly efficient capture of circulating tumor cells (CTCs) and further accurate clinical diagnosis of prostate cancer are reported . The unprecedented construction of nano-filopodia on polymer-based magnetic particles is achieved by introducing electrostatic interactions in emulsion interfacial polymerization. Due to the unique nano-filopodia, the NFMPs allow remarkably enhanced CTCs capture efficiency (86.5% ± 2.8%) compared with smooth magnetic particles (SMPs, 35.7% ± 5.7%). Under the assistance of machine learning by combining with prostate-specific antigen (PSA) and free to total PSA (F/T-PSA), the NFMPs strategy demonstrates high sensitivity (100%), high specificity (93.3%), and a high area under the curve (AUC) value (98.1%) for clinical diagnosis of prostate cancer in the PSA gray zone. The NFMPs are anticipated as an efficient platform for CTCs-based liquid biopsy toward early cancer diagnosis and prognosis evaluation.

Decreased fucosylated PSA as a urinary marker for high Gleason score prostate cancer

Fucosylation is an important oligosaccharide modification associated with cancer and inflammation. We investigated whether urinary fucosylated PSA (Fuc-PSA) levels could be used for the detection of high Gleason score prostate cancer. Urine samples were collected from men with abnormal digital rectal examination findings or elevated serum PSA levels, before prostate biopsy. Lectin-antibody ELISA was used to quantify the Lewis-type or core-type fucosylated PSA (PSA-AAL) and core-type fucosylated PSA (PSA-PhoSL) in the urine samples. Both types of urinary Fuc-PSA were significantly decreased in the men with prostate cancer compared with the men whose biopsies were negative for cancer (P = 0.026 and P < 0.001, respectively). Both were also significantly associated with the Gleason scores of the biopsy specimens (P = 0.001 and P < 0.001, respectively). Multivariate analysis showed that PSA density, urinary PSA-AAL, and urinary PSA-PhoSL were independent predictors of high Gleason score prostate cancer. The area under the receiver-operator characteristic curve (AUC) value for the prediction of cancers of Gleason score ≥ 7 was 0.69 for urinary PSA-AAL and 0.72 for urinary PSA-PhoSL. In contrast, the AUC value was 0.59 for serum PSA, 0.63 for PSA density, and 0.58 for urinary PSA. In conclusion, a decreased urinary Fuc-PSA level is a potential marker for the detection of high Gleason score prostate cancer.

Analysis of urinary PSA glycosylation is not indicative of high-risk prostate cancer

The levels of core fucosylation and α2,3-linked sialic acid in serum Prostate Specific Antigen (PSA), using the lectins Pholiota squarrosa lectin (PhoSL) and Sambucus nigra agglutinin (SNA), can discriminate between Benign Prostatic Hyperplasia (BPH) and indolent prostate cancer (PCa) from aggressive PCa. In the present work we evaluated whether these glycosylation determinants could also be altered in urinary PSA obtained after digital rectal examination (DRE) and could also be useful for diagnosis determinations. For this purpose, α2,6-sialic acid and α1,6-fucose levels of urinary PSA from 53 patients, 18 biopsy-negative and 35 PCa patients of different aggressiveness degree, were analyzed by sandwich ELLA (Enzyme Linked Lectin Assay) using PhoSL and SNA. Changes in the levels of specific glycosylation determinants, that in serum PSA samples were indicative of PCa aggressiveness, were not found in PSA from DRE urine samples. Although urine is a simpler matrix for analyzing PSA glycosylation compared to serum, an immunopurification step was necessary to specifically detect the glycans on the PSA molecule. Those specific glycosylation determinants on urinary PSA were however not useful to improve PCa diagnosis. This could be probably due to the low proportion of PSA from the tumor in urine samples, which precludes the identification of aberrantly glycosylated PSA.

Evaluation of sulfur isotopic enrichment of urine metabolites for the differentiation of healthy and prostate cancer mice after the administration of 34S labelled yeast

Sulfur isotopic enrichment of urine metabolites in healthy and prostate cancer mice using ³⁴S enriched yeast and High Performance Liquid Chromatography coupled to Multicollector Inductively Coupled Plasma Mass Spectrometry (HPLC-MC-ICP-MS) has been evaluated. A 30 weeks experiment (since the eleventh to the fortieth week of life) was carried out collecting the urine of three healthy mice and three transgenic mice with prostate cancer during 24h after a single oral administration of a ³⁴S enriched yeast slurry. The isotopic enrichment of different sulphur metabolites was monitored by coupling a C18 reverse phase HPLC column with a multicollector ICP-MS using a membrane desolvating system. Quantification of sulfur in the chromatographic peaks was carried out by post-column isotope dilution using a ³³S enriched spike. Differences between the ³⁴S enrichment in the urine metabolites of healthy and prostate cancer mice were found from the beginning of the disease. Both populations could be differentiated using a principal component analysis (PCA). Finally, 7 unknown mice were correctly classified in each population using a linear discriminant analysis.

Analysis of Urinary Prostate-Specific Antigen Glycoforms in Samples of Prostate Cancer and Benign Prostate Hyperplasia

Glycans of prostate-specific antigen (PSA) in prostate cancer were found to be different from that in benign disease. It is difficult to analyze heterogeneous PSA glycoforms in each individual specimen because of low protein abundance and the limitation of detection sensitivity. We developed a method for prostate cancer diagnosis based on PSA glycoforms. Specific glycoforms were screened in each clinical sample based on liquid chromatography-tandem mass spectrometry with ion accumulation. To look for potential biomarkers, normalized abundance of each glycoform in benign prostate hyperplasia (BPH) and in prostate cancer was evaluated. The PSA glycoform, Hex5HexNAc4NeuAc1dHex1, and monosialylated, sialylated, and unfucosylated glycoforms differed significantly between the prostate cancer and BPH samples. The detection sensitivity (87.5%) and specificity (60%) for prostate cancer identification are higher than those of the serum PSA marker. As low as 100 amol PSA could be detected with the ion accumulation method which has not been reported before. The improved detection specificity can help reduce unnecessary examinations.

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.

Urinary PSA: a potential useful marker when serum PSA is between 2.5 ng/mL and 10 ng/mL

INTRODUCTION

Our objective was to evaluate the usefulness of urinary prostate specific antigen (PSA) in the differential diagnosis of benign prostatic hyperplasia (BPH) and prostate cancer.

METHODS

We undertook a prospective study and obtained informed consent from 170 men. They provided blood samples to measure serum PSA and 50 mL of first-voided urine to measure urinary PSA. Seventy-seven men were diagnosed with BPH; 42 patients had newly diagnosed prostate cancer; and 51 were selected as age-matched control subjects. Data were analyzed using Wilcoxon signed rank tests, receiver operating characteristic (ROC) curves and logistic regression.

RESULTS

Prostate volume was 35 cm(3) and 45 cm(3) (p < 0.05), serum PSA was 9.7 ng/mL and 4.5 ng/mL (p < 0.001) and PSA density was 0.28 and 0.11 (p < 0.01) for prostate cancer and BPH patients, respectively. Overall, urinary PSA was not significantly different, but PSA ratio (urinary:serum) was significantly different at 6.7 and 30.6 (p < 0.001) for prostate cancer and BPH patients, respectively. A subgroup with serum PSA between 2.5 ng/mL and 10.0 ng/mL was selected and urinary PSA was significant: 52.6 ng/mL (n = 29) and 123.2 ng/mL (n = 35) (p < 0.05) for prostate cancer and BPH patients, respectively. PSA ratios were also significant (p = 0.007). ROC curves identified a cutoff for urinary PSA at > 150 ng/mL, with a sensitivity of 92.5%. When comparing prostate cancer patients with age-matched control subjects, serum PSA, urinary PSA and PSA ratio were different (p = 0.004).

CONCLUSION

Our study supports urinary PSA as a useful marker in the differential diagnosis of prostate cancer and BPH, especially when serum PSA is between 2.5 ng/mL and 10 ng/mL. Low urinary PSA and PSA ratios point toward prostate cancer. A urinary PSA threshold of > 150 ng/mL may be used to decrease the number of prostatic biopsies.

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.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Glycosylation of prostate specific antigen and its potential diagnostic applications

Prostate specific antigen (PSA) assays are widely used for early detection of prostate cancer. However, those analyses are associated with considerable sensitivity and specificity problems. Several approaches have been developed to tackle this issue. PSA is a glycoprotein, which is primarily produced by the prostatic epithelial cells. Aberrant glycosylation modification of proteins is a fundamental characteristic of tumorigenesis. Study of PSA glycoforms offers interesting diagnostic perspectives. Modern technology allows us to analyze PSA glycoforms in a variety of clinical samples (serum or plasma, urine, seminal fluid, tissue). A number of novel techniques, such as lectin-based detection methods, mass spectrometry, 2-dimensional electrophoresis and capillary electrophoresis have been developed to analyze PSA glycosylation. This article reviews the technical and diagnostic aspects of PSA glycoforms.

Early detection of prostate cancer local recurrence by urinary prostate-specific antigen

PURPOSE

We assessed the role of urinary prostate-specific antigen (uPSA) in the follow-up of prostate cancer after retropubic radical prostatectomy (RRP) for the early detection of local recurrences.

METHODS

We recruited 50 patients previously treated for prostate cancer with RRP and who had not experienced a prostate-specific antigen (PSA) recurrence within their first postoperative year into a cross-sectional laboratory assessment and prospective 6-year longitudinal follow-up study. We defined biochemical failure as a serum PSA (sPSA) of 0.3 μg/L or greater. Patients provided blood samples and a 50-mL sample of first-voided urine. We performed Wilcoxon rank-sum and Fisher exact tests for statistical analysis.

RESULTS

The median sPSA was 0.13 μg/L. The median uPSA was 0.8 μg/L, and was not significantly different when comparing Gleason scores or pathological stages. Of the 50 patients, 27 initially had a nondetectable sPSA but a detectable uPSA, and 11 patients experienced sPSA failure after 6 years. Six patients had detectable sPSA and uPSA initially. Fifteen patients were negative for both sPSA and uPSA, and 13 remained sPSA-free after 6 years. The odds ratio (OR) of having sPSA failure given a positive uPSA test was 4.5 if sPSA was undetectable, but was reduced to 2.6 if sPSA was detectable. The pooled Mantel-Haenszel OR of 4.2 suggested that a detectable uPSA quadrupled the risk of recurrence, independent of whether sPSA was elevated or not. The sensitivity of uPSA for detecting future sPSA recurrences was 81% and specificity was 45%.

CONCLUSION

Urinary PSA could contribute to an early detection of local recurrences of prostate cancer after a radical prostatectomy.

Tumour markers in prostate cancer III: biomarkers in urine

The serum PSA test still is the most important biomarker for the detection and follow-up of prostate cancer. PSA-based screening can reduce disease specific mortality but coinciding unnecessary testing and overdiagnosis warrant further research for more specific biomarkers. Numerous studies of both serum and urine-based prostate cancer biomarker candidates have been presented the last ten years. However, biomarkers for identifying the most aggressive subsets of this malignancy are still missing. Being non-invasive, urine-based tests might be suitable for both clinical and (mass) screening purposes, but also for prediction and to gain prognostic information. Protein-based, DNA-based and RNA-based urine biomarkers have been developed and tested.

PROTEIN MARKERS IN URINE

Data on protein-based urine biomarkers (i.e. Annexin A3, matrix metalloproteinases and the urinary:serum PSA ratio) show up to now contradictory results and further studies are warranted to be able to assess their clinical value in which the cost aspect should not be overlooked. DNA markers in urine. Studies on DNA-based urine biomarkers focus on hypermethylation of gene panels with GSTP1 hypermethylation being the most promising individual marker. Larger prospective clinical studies of single markers and gene panels are however needed to validate their clinical utility.

RNA MARKERS IN URINE

RNA-based urine biomarkers are by far the most developed. The PCA3 test, the TMPRSS2-ERG fusion gene, transcript expression levels of GOLPH2, SPINK1 and their combination have been subject of many studies showing encouraging results.

CONCLUSION

Up to now urine-based biomarkers represent a promising alternative or addition to serum-based biomarkers. Prospective studies in a multivariate setting, including larger sample sizes and avoiding attribution bias caused by preselection on the basis of serum PSA are however required.

What are the possible reasons for urethral PSA varieties after radical prostatectomy?

OBJECTIVE

To examine the possible reasons for great varieties in urethral prostate specific antigen (urPSA) levels, in patients after radical prostatectomy (RP).

MATERIALS AND METHODS

In 46 patients with pros-tate cancer, PSA, urPSA, total testosterone, body-mass index (BMI) and the stage of androgenic alopecia (AGA) were determined. Forty-five patients underwent retropubic RP, while one underwent cystoprostatectomy with orthotopic bladder construction, due to bladder cancer.

RESULTS

Average patients age prior to surgery plus or minus standard deviation was 65.2 +/- 5.8 years. Average urPSA was 20.9 +/- 47.5 ng/ml (0.05 to 212 ng/ml, median 2.24 ng/ml). With urethral PSA cut-off of 2.0 ng/ml, two groups were formed: A (urPSA < 2.0 ng/ml) and B (urPSA = 2.0 ng/ml). Patients in the group A had significantly lower average AGA score, than the patients from the group B (2.4 +/- 1.3 vs. 4.4 +/- 2.2, p = 0.0003). In addition, patients from the group A had significantly lower pos-toperative PSA (0.07+0.08 ng/ml vs. 0.14 +/- 0.06 ng/ml, p = 0.0014).

CONCLUSIONS

The patients with higher urPSA have higher AGA scores and higher postoperative PSA. This phenomenon is probably the consequence of higher local dihydrotestosterone activity in the scalp and PSA-secreting urethral glands.

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.

Clinical collection and protein properties of expressed prostatic secretions as a source for biomarkers of prostatic disease

The prostate gland secretes many proteins in a prostatic fluid that combines with seminal vesicle derived fluids to promote sperm activation and function. Proximal fluids of the prostate that can be collected clinically are seminal plasma and expressed-prostatic secretion (EPS) fluids. EPS represents the fluid being secreted by the prostate following a digital rectal prostate massage, which in turn can be collected in voided urine post-exam. This collection is not disruptive to a standard urological exam, and it can be repeatedly collected from men across all prostatic disease states. A direct EPS fluid can also be collected under anesthesia prior to prostatectomy. While multiple genetic assays for prostate cancer detection are being developed for the shed epithelial cell fraction of EPS urines, the remaining fluid that contains many prostate-derived proteins has been minimally characterized. Approaches to optimization and standardization of EPS collection consistent with current urological exam and surgical practices are described, and initial proteomic and glycomic evaluations of the of EPS fluid are summarized for prostate specific antigen and prostatic acid phosphatase. Continued characterization of the prostate specific protein components of EPS urine combined with optimization of clinical collection procedures should facilitate discovery of new biomarkers for prostate cancer.

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 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.

Urinary prostate specific antigen: is the clinical use likely?

Prostate specific antigen (PSA) blood test represents the standard procedure in prostate cancer (CaP) diagnosis and follow-up. However, determination of PSA in the urine, where PSA is present in much higher concentrations than in the blood, still remains in the field of research.

OBJECTIVES

To determine urinary concentrations of PSA (uPSA) in different groups of patients (pts.), and to estimate is it possible to differentiate benign and malignant prostate diseases and to follow-up the results of treatment.

METHODS

Between January 2001. and November 2003., urinary concentrations of PSA were determined at 142 pts. divided in seven groups: 1. young and healthy volunteers, 2. "BPH-24": pts. with benign prostatic hyperplasia (BPH) who collected the sample of 24-hour voided urine, 3. "BPH-I": pts. with BPH who collected the first portion of first urinary voiding, 4. "TRUS-CaP": pts. with CaP which gave the first portion of urine just prior to transrectal ultrasound-guided prostate biopsy (TRUS- biopsy), 5. "TRUS-non-CaP": pts. who gave first portion of urine prior to TRUS-biopsy, but biopsy did not prove the presence of CaP, 6. "RRP": pts. who underwent radical retropubic prostatectomy (RRP), 7. "AAT": pts. who underwent androgen deprivation therapy.

RESULTS

Average uPSA value in the group of young and healthy volunteers, was 13.8 +/- 19.6 ng/ml, in "BPH-24": 38.0 +/- 44.4 ng/ml, in "BPH-I": 140.8 +/- 140.9 ng/ml, in "TRUS-CaP": 234.8 +/- 277.7 ng/ml, in TRUS-non-CaP: 113.1 +/- 148.5 ng/ml, and in the group "RRP": 4.4 +/- 4.7 ng/ml. There was no statistically significant difference of average uPSA values between "BPH-I" and "TRUS-CaP" groups. The significant difference was found between the group of young volunteers and "BPH-I". In "TRUS-CaP" group, there was strong correlation between tumour size and aggressivenes and uPSA concentration. Finally, PSA and uPSA decline during androgen deprivation therapy, strongly correlated (up to r = 0.95).

CONCLUSIONS

Determination of uPSA cannot differentiate BPH and CaP. However, in the group of pts. with proven localized CaP, uPSA can provide additional information concerning T-staging. Moreover, simultaneous monitoring of PSA and uPSA response on hormonal therapy, can provide an early recognition of androgen-indiferent CaP (AIPCA) and hormone-resistent CaP (HRPCA).

Large-scale and high-confidence proteomic analysis of human seminal plasma

BACKGROUND

The development of mass spectrometric (MS) techniques now allows the investigation of very complex protein mixtures ranging from subcellular structures to tissues. Body fluids are also popular targets of proteomic analysis because of their potential for biomarker discovery. Seminal plasma has not yet received much attention from the proteomics community but its characterization could provide a future reference for virtually all studies involving human sperm. The fluid is essential for the survival of spermatozoa and their successful journey through the female reproductive tract.

RESULTS

Here we report the high-confidence identification of 923 proteins in seminal fluid from a single individual. Fourier transform MS enabled parts per million mass accuracy, and two consecutive stages of MS fragmentation allowed confident identification of proteins even by single peptides. Analysis with GoMiner annotated two-thirds of the seminal fluid proteome and revealed a large number of extracellular proteins including many proteases. Other proteins originated from male accessory glands and have important roles in spermatozoan survival.

CONCLUSION

This high-confidence characterization of seminal plasma content provides an inventory of proteins with potential roles in fertilization. When combined with quantitative proteomics methodologies, it should be useful for studies of fertilization, male infertility, and prostatic and testicular cancers.

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.

Molecular forms of human prostate-specific antigen in urine of subjects with benign prostatic hyperplasia

In the present study, we examined mollecular forms of urinary prostate-specific antigen (PSA), focusing on its structural complexity in general and specifically on its microheterogeneity in relation to benign prostatic hyperplasia (BPH). Gel filtration, ion-exchange chromatography, and lectin-affinity chromatography were used to characterize PSA. In comparing the binding pattern of PSA isoforms, moderate changes were observed in the relative abundance of distinct molecular subpopulations separated on lectin-affinity columns. They may be related to alteration in the position and type of linkage of fucose or sialic acid, as well as to modification of the trimannosyl core by branching of the PSA oligosaccharide chain.

Urinary/serum prostate-specific antigen ratio: comparison with free/total serum prostate-specific antigen ratio in improving prostate cancer detection

OBJECTIVES

To test the previously reported hypothesis, that the urinary/total serum (U/S) prostate-specific antigen (PSA) ratio improves the detection of prostate cancer, by evaluating the clinical usefulness of the U/S PSA ratio and comparing it with the free/total (F/T) serum PSA ratio.

METHODS

A total of 165 patients undergoing transrectal ultrasound-guided prostate biopsy were prospectively included in this multicenter study. In all patients, PSA was measured from preoperative serum and 12-hour urine specimens in a centralized laboratory.

RESULTS

Prostate cancer was identified in 83 of 165 patients. The differences between patients with and without prostate cancer were statistically significant (P <0.001) when considering the total PSA value (median, 10.2 ng/mL and 6.6 ng/mL respectively), F/T serum PSA ratio (0.11 and 0.18), and U/S PSA ratio (1.2 and 4.2). In the group of 79 patients with a PSA level between 4 and 10 ng/mL, receiver operating characteristic curves showed that the U/S PSA ratio was associated with a larger area under the curve (0.63; 95% confidence interval, 0.51 to 0.73) than the total PSA value (0.55; 95% confidence interval, 0.43 to 0.66) or F/T serum PSA ratio (0.60; 95% confidence interval, 0.49 to 0.71). The U/S PSA ratio did not correlate with patient age or prostate volume.

CONCLUSIONS

Our results confirmed that the U/S PSA ratio may be a useful test in prostate cancer detection when the total serum PSA level is between 4 and 10 ng/mL. The F/T serum PSA ratio and U/S PSA ratio did not correlate. This suggests that these two tests could complement each other.

Glycosylation of urinary prostate-specific antigen in benign hyperplasia and cancer: assessment by lectin-binding patterns

OBJECTIVES

In the present study, we examined the glycosylation of urinary prostate-specific antigen (PSA) from benign prostatic hyperplasia (BPH) and prostate cancer (PCa) subjects, specifically looking at alterations in its oligosaccharide chain as a potential biomarker of these pathophysiological conditions.

DESIGN AND METHODS

First morning urine voids were collected from subjects with PCa and BPH before initiation of any treatment. Urinary PSA was characterized by ion-exchange chromatography, followed by lectin affinity chromatography on the columns using immobilized plant lectins.

RESULTS

Four isoforms of urinary PSA from both BPH and PCa samples were separated by ion-exchange chromatography. The elution profiles from lectin-affinity columns reflected molecular heterogeneity of PSA isoforms and the main differences observed were in the reactivity to Ulex europaeus agglutinin, Aleuria aurantia agglutinin, Phaseolus vulgaris erythroagglutinin and Phaseolus vulgaris leukoagglutinin.

CONCLUSIONS

The observed differences in the lectin reactivities between BPH PSA and PCa PSA may be of clinical importance in the evaluation of prostate health.

Urine based markers of urological malignancy

PURPOSE

A number of urine based markers have been and are being investigated for the diagnosis and prognostication of urological conditions. A majority of these markers have been evaluated in urological neoplasms, particularly bladder cancer. The diagnosis of bladder cancer currently relies on identifying malignant cells in the urine and subsequently visualizing the tumor on cystoscopy. This diagnosis is further confirmed by transurethral resection or biopsy. While urine cytology is specific, it is not sensitive, especially for detecting low grade disease. This characteristic has prompted the search for more accurate markers of bladder cancer. In this review we critically examine the results of studies evaluating various markers for bladder cancer.

MATERIALS AND METHODS

The published literature on urine based markers for all urological diseases, particularly bladder cancer, was identified using a MEDLINE search and critically analyzed. The sensitivity, specificity, positive and negative predictive values of the various markers were compared. The benefit of using combined markers rather than a single marker was also analyzed from published reports.

RESULTS

Most published literature on urine based markers for urological malignancies involve such markers for diagnosing and prognosticating bladder cancer. Hence, we focused mainly on urine based markers in bladder cancer. Most markers appear to have an advantage over urine cytology in terms of sensitivity, especially for detecting low grade, superficial tumors. However, most markers tend to be less specific than cytology, yielding more false-positive results. This scenario is more common in patients with concurrent bladder inflammation or other benign bladder conditions. However, there is reason to be optimistic about several new markers that appear to provide better specificity. Few urine based markers have been identified and investigated in other urological tumors.

CONCLUSIONS

Detecting bladder cancer using diagnostic markers still presents a challenge. A number of new markers are currently available that appear to be significantly more accurate than cytology. However, further studies involving a larger number of patients are required to determine their accuracy and widespread applicability for diagnosing bladder cancer. Urine based markers do not appear to have a significant role in the diagnosis or prognosis of other urological malignancies, such as prostate, kidney or testicular cancer.

Highly Sensitive Automated Chemiluminometric Assay for Measuring Free Human Glandular Kallikrein-2

Background: Human glandular kallikrein (hK2) is a serine protease that has 79% amino acid identity with prostate-specific antigen (PSA). Both free hK2 and hK2 complexed to α1-antichymotrypsin (ACT) are present in the blood in low concentrations. We wished to measure hK2 in serum with limited contribution from hK2-ACT for the results.

Methods: We developed an automated assay for hK2 with use of a select pair of monoclonal antibodies. The prototype assay was implemented on a Beckman Coulter ACCESS® analyzer.

Results: The detection limit of the assay was 1.5 ng/L, the “functional sensitivity” (day-to-day CV &lt;15%) was &lt;4 ng/L, cross-reactivity with PSA and PSA-ACT was negligible, and cross-reactivity with hK2-ACT was 2%. After surgical removal of prostate glands, serum hK2 was &lt;7 ng/L and was &lt;15 ng/L in most healthy women. The median serum concentration of hK2 in healthy men without prostate cancer was 26 ng/L. The median concentration of hK2 was 72 ng/L for men having prostate cancer with lower Gleason scores compared with 116 ng/L for men with more advanced cancer. The concentration of hK2 correlated weakly with PSA, with the mean hK2 concentrations generally 30- to 80-fold lower than PSA concentrations.

Conclusion: The availability of a robust, high sensitivity automated assay for hK2 should facilitate further investigations of the role of hK2 measurements in the management of patients with prostate disease.

Human Kallikrein 2 (hK2) and prostate-specific antigen (PSA): two closely related, but distinct, kallikreins in the prostate

Recent studies on human kallikrein 2 (hK2) have revealed striking similarities and significant differences with the closely related kallikrein PSA. Both PSA and hK2 are primarily localized to the prostate and share close structural similarities. Although both kallikreins are produced by the same secretory epithelial cells in the prostate, hK2 is associated more with prostate tumors than PSA and is highly expressed in poorly differentiated cancer cells. The potent trypsin-like activity of hK2 contrasts with the weak chymotrypsin-like activity of PSA. The inactive precursor form of PSA, proPSA, is converted rapidly to active PSA by hK2, suggesting an important in vivo regulatory function by hK2 on PSA activity. The high homology between hK2 and PSA results in significant cross-reactivity to hK2 by polyclonal and some monoclonal antibodies to PSA. Future studies on both PSA and hK2 need to take into account this potential for cross-reactivity. Specific monoclonal antibodies to hK2 have now demonstrated that serum levels of hK2, like PSA, are correlated with prostate cancer. The production of hK2 protein in active protease form and specific monoclonal antibodies to the hK2 antigen will allow extensive future studies delineating the physiological and clinical utility of this new prostate antigen.