PSA and other tissue kallikreins for prostate cancer detection

Preclinical models of prostate cancer - modelling androgen dependency and castration resistance in vitro, ex vivo and in vivo

Prostate cancer is well known to be dependent on the androgen receptor (AR) for growth and survival. Thus, AR is the main pharmacological target to treat this disease. However, after an initially positive response to AR-targeting therapies, prostate cancer will eventually evolve to castration-resistant prostate cancer, which is often lethal. Tumour growth was initially thought to become androgen-independent following treatments; however, results from molecular studies have shown that most resistance mechanisms involve the reactivation of AR. Consequently, tumour cells become resistant to castration - the blockade of testicular androgens - and not independent of AR per se. However, confusion still remains on how to properly define preclinical models of prostate cancer, including cell lines. Most cell lines were isolated from patients for cell culture after evolution of the tumour to castration-resistant prostate cancer, but not all of these cell lines are described as castration resistant. Moreover, castration refers to the blockade of testosterone production by the testes; thus, even the concept of "castration" in vitro is questionable. To ensure maximal transfer of knowledge from scientific research to the clinic, understanding the limitations and advantages of preclinical models, as well as how these models recapitulate cancer cell androgen dependency and can be used to study castration resistance mechanisms, is essential.

Electrochemical Immunosensor for Detection of CCR4 Cancer Biomarker in Human Serum: An Alternative Strategy for Modification of Disposable ITO Electrode

Herein, a new strategy for the fabrication of a sensitive immunosensor capable of determination of CC Chemokine receptor 4 (CCR4) in complex serum samples is developed through the polymer modification on the disposable indium tin oxide electrode. Anti-CCR4 antibodies, which are utilized as sensing biomolecules, are covalently attached on the succinimide groups of polypyrrole polymer (PPyr-CSsg). The constructed immunosensor illustrates promising performances for the quantification of CCR4 antigen, with a linear detection range of 0.024-12 pg mL^-1 and a low detection limit of 7.3 fg mL^-1 , calculated at a signal-to-noise ratio of 3. In addition, the impedimetric immunosensor displays a very successful analytical performance in terms of sensitivity, selectivity, repeatability, reproducibility, and long-term stability as well as successful applicability for the accurate quantification of CCR4 in human serum samples. The constructed immunosensor is successfully used for quantification of CCR4 antigen in human serums. In addition, the immunosensor displays only 27.54% loss in its initial signal after nine weeks storage at 4 °C. Moreover, the fabricated immunosensor is economical, highly sensitive, and selective for CCR4 antigen detection, and suitable for potential application in clinical diagnosis.

Activation and activity of glycosylated KLKs 3, 4 and 11

Human kallikrein-related peptidases 3, 4, 11, and KLK2, the activator of KLK3/PSA, belong to the prostatic group of the KLKs, whose major physiological function is semen liquefaction during the fertilization process. Notably, these KLKs are upregulated in prostate cancer and are used as clinical biomarkers or have been proposed as therapeutic targets. However, this potential awaits a detailed characterization of these proteases. In order to study glycosylated prostatic KLKs resembling the natural proteases, we used Leishmania (LEXSY) and HEK293 cells for secretory expression. Both systems allowed the subsequent purification of soluble pro-KLK zymogens with correct propeptides and of the mature forms. Periodic acid-Schiff reaction, enzymatic deglycosylation assays, and mass spectrometry confirmed the glycosylation of these KLKs. Activation of glycosylated pro-KLKs 4 and 11 turned out to be most efficient by glycosylated KLK2 and KLK4, respectively. By comparing the glycosylated prostatic KLKs with their non-glycosylated counterparts from Escherichia coli, it was observed that the N-glycans stabilize the KLK proteases and change their activation profiles and their enzymatic activity to some extent. The functional role of glycosylation in prostate-specific KLKs could pave the way to a deeper understanding of their biology and to medical applications.

Discovery of novel transcripts of the human tissue kallikrein (KLK1) and kallikrein-related peptidase 2 (KLK2) in human cancer cells, exploiting Next-Generation Sequencing technology

Tissue kallikrein, kallikrein-related peptidases (KLKs), and plasma kallikrein form the largest group of serine proteases in the human genome, sharing many structural and functional properties. Several KLK transcripts have been found aberrantly expressed in numerous human malignancies, confirming their prognostic or/and diagnostic values. However, the process of alternative splicing can now be studied in-depth due to the development of Next-Generation Sequencing (NGS). In the present study, we used NGS to discover novel transcripts of the KLK1 and KLK2 genes, after nested touchdown PCR. Bioinformatics analysis and PCR experiments revealed a total of eleven novel KLK transcripts (two KLK1 and nine KLK2 transcripts). In addition, the expression profiles of each novel transcript were investigated with nested PCR experiments using variant-specific primers. Since KLKs are implicated in human malignancies, qualifying as potential biomarkers, the quantification of the presented novel transcripts in human samples may have clinical applications in different types of cancer.

Clinical utility of kallikrein-related peptidases (KLK) in urogenital malignancies

Kallikrein-related peptidases (KLK), which represent a major tissue-associated proteolytic system, stand for a rich source of biomarkers that may allow molecular classification, early diagnosis and prognosis of human malignancies as well as prediction of response or failure to cancer-directed drugs. International research points to an important role of certain KLKs in female and male urogenital tract malignancies, in addition to cancers of the lung, brain, skin, head and neck, and the gastrointestinal tract. Regarding the female/male urogenital tract, remarkably, all of the KLKs are expressed in the normal prostate, testis, and kidney whereas the uterus, the ovary, and the urinary bladder are expressing a limited number of KLKs only. Most of the information regarding KLK expression in tumour-affected organs is available for ovarian cancer; all of the 12 KLKs tested so far were found to be elevated in the malignant state, depicting them as valuable biomarkers to distinguish between the normal and the cancerous phenotype. In contrast, for kidney cancer, a series of KLKs was found to be downregulated, while other KLKs were not expressed. Evidently, depending on the type of cancer or cancer stage, individual KLKs may show characteristics of a Janus-faced behaviour, by either expanding or inhibiting cancer progression and metastasis.

Up-regulation of SERPINA3 correlates with high mortality of melanoma patients and increased migration and invasion of cancer cells

Serpin Peptidase Inhibitor, clade A member 3 (SERPINA3) was found to be abnormally overexpressed in a subset of melanoma tissue biopsies. High SERPINA3 expression was also associated with poor patient survival. In this study, we set out to test SERPINA3 protein's prognostic potential with a larger-sized and independent patient cohort, and to explore SERPINA3's function in melanoma cells. Tissue microarray-based immunohistochemistry analysis showed a significant increase in SERPINA3 expression in invasive and metastatic melanomas compared to normal nevi and melanoma-in-situ (P < 0.001, Chi-square test). In melanoma patients, high SERPINA3 expression was strongly associated with worse overall and disease specific survival at 5 years. Multivariate Cox regression analysis showed that SERPINA3 expression is an independent prognostic factor to predict melanoma patient clinical outcome. When SERPINA3 expression was selectively silenced using small interfering RNA molecules (siRNA) in cultured melanoma cell lines, cell migration and matrix invasion was significantly decreased, but no change in cell proliferation was observed.This study confirms the prognostic potential of SERPINA3 expression in human cutaneous melanoma and reveals the pro-migration and pro-invasion functions of this protein on melanoma cells.

The new insight of prostate-specific antigen reduction during finasteride therapy in aging men

OBJECTIVE

To evaluate the effect of finasteride on prostate-specific antigen (PSA) in Chinese population.

MATERIALS AND METHODS

From Feb 2011 to Jan 2012, 83 benign prostatic hyperplasia (BPH) patients with prostate volume (PV) >30 mL were enrolled in our study. All the patients were older than 50 years and all of them received combined therapy (finasteride + doxazosin). All the patients were required for 1-year follow-up. PSA level and PV was measured at the start, 6 and 12 months, respectively.

RESULTS

79 patients completed the follow up. PSA level reduced by approximately 40 % during finasteride therapy. We defined baseline PSA as PSA1, PSA at 6 months as PSA2, PSA at 12 months as PSA3. PSA1 was significantly correlated with PSA2/PSA1 and PSA3/PSA1. However, prostate volume was not correlated with PSA1. We divided the patients into three groups according to PSA level. Groups 1, 2, 3 represented the patients with PSA less than 2 ng/mL, between 2 and 4 ng/mL and greater than 4 ng/mL, respectively. Both the PSA2/PSA1 and the PSA3/PSA1 had significant difference among three groups. Furthermore, group 1 and group 2 both showed the fairly large data variance.

CONCLUSIONS

When baseline PSA level was greater than 4 ng/mL, the doubling rule could be used for screening. When baseline PSA level was less than 4 ng/Ml, the doubling rule might not be an accurate predictor. We can use the PSA rise from nadir or proPSA to predict prostate cancer.

Using Serological Proteome Analysis to Identify Serum Anti-Nucleophosmin 1 Autoantibody as a Potential Biomarker in European-American and African-American Patients With Prostate Cancer

BACKGROUND

The prostate-specific antigen (PSA) testing has been widely implemented for the early detection and management of prostate cancer (PCa). However, the lack of specificity has led to overdiagnosis, resulting in many possibly unnecessary biopsies and overtreatment. Therefore, novel serological biomarkers with high sensitivity and specificity are of vital importance needed to complement PSA testing in the early diagnosis and effective management of PCa. This is particularly critical in the context of PCa health disparities, where early detection and management could help reduce the disproportionately high PCa mortality observed in African-American men. Previous studies have demonstrated that sera from patients with PCa contain autoantibodies that react with tumor-associated antigens (TAAs).

METHODS

The serological proteome analysis (SERPA) approach was used to identify tumor-associated antigens (TAAs) of PCa. In evaluation study, the level of anti-NPM1 antibody was examined in sera from test cohort, validation cohort, as well as European-American (EA) and African-American (AA) men with PCa by using immunoassay.

RESULTS

Nucleophosmin 1 (NPM1) as a 33 kDa TAA in PCa was identified and characterized by SERPA approach. Anti-NPM1 antibody level in PCa was higher than in benign prostatic hyperplasia (BPH) patients and healthy individuals. Receiver operating characteristic (ROC) curve analysis showed similar high diagnostic value for PCa in the test cohort (area under the curve (AUC):0.860) and validation cohort (AUC: 0.822) to differentiate from normal individuals and BPH. Interestingly, AUC values were significantly higher for AA PCa patients. When considering concurrent serum measurements of anti-NPM1 antibody and PSA, 97.1% PCa patients at early stage were identified correctly, while 69.2% BPH patients who had elevated PSA levels were found to be anti-NPM1 negative. Additionally, anti-NPM1 antibody levels in PCa patients at early stage significantly increased after surgery treatment.

CONCLUSION

This intriguing data suggested that NPM1 can elicit autoantibody response in PCa and might be a potential biomarker for the immunodiagnosis and prognosis of PCa, and for supplementing PSA testing in distinguishing PCa from BPH. Prostate 76:1375-1386, 2016. © 2016 Wiley Periodicals, Inc.

Proteinases, Their Extracellular Targets, and Inflammatory Signaling

Given that over 2% of the human genome codes for proteolytic enzymes and their inhibitors, it is not surprising that proteinases serve many physiologic-pathophysiological roles. In this context, we provide an overview of proteolytic mechanisms regulating inflammation, with a focus on cell signaling stimulated by the generation of inflammatory peptides; activation of the proteinase-activated receptor (PAR) family of G protein-coupled receptors (GPCR), with a mechanism in common with adhesion-triggered GPCRs (ADGRs); and by proteolytic ion channel regulation. These mechanisms are considered in the much wider context that proteolytic mechanisms serve, including the processing of growth factors and their receptors, the regulation of matrix-integrin signaling, and the generation and release of membrane-tethered receptor ligands. These signaling mechanisms are relevant for inflammatory, neurodegenerative, and cardiovascular diseases as well as for cancer. We propose that the inflammation-triggering proteinases and their proteolytically generated substrates represent attractive therapeutic targets and we discuss appropriate targeting strategies.

Current biomarkers for diagnosing of prostate cancer

Prostate cancer (PCa) is mostly detected by prostate-specific antigen (PSA) as one of the most widely used tumor markers. But PSA is limited with its low specificity. The prostate health index (phi) can improve specificity over percent free and total PSA and correlates with aggressive cancer. The urinary PCA3 also shows its utility to detect PCa but its correlation with aggressiveness and the low sensitivity at high values are limitations. While the detection of alterations of the androgen-regulated TMPRSS2 and ETS transcription factor genes in tissue of ˜50% of all PCa patients was one research milestone, the urinary assay should only be used in combination with PCA3. Both US FDA-approved markers phi and PCA3 perform equally.

miR-503 suppresses tumor cell proliferation and metastasis by directly targeting RNF31 in prostate cancer

Microarray data analyses were performed to search for metastasis-associated oncogenes in prostate cancer (PCa). RNF31 mRNA expressions in tumor tissues and benign prostate tissues were evaluated. The RNF31 protein expression levels were also analyzed by western blot and immunohistochemistry. Luciferase reporter assays were used to identify miRNAs that can regulate RNF31. The effect of RNF31 on PCa progression was studied in vitro and in vivo. We found that RNF31 was significantly increased in PCa and its expression level was highly correlated with seminal vesicle invasion, clinical stage, prostate specific antigen (PSA) level, Gleason score, and BCR. Silence of RNF31 suppressed PCa cell proliferation and metastasis in vitro and in vivo. miR-503 can directly regulate RNF31. Enforced expression of miR-503 inhibited the expression of RNF31 significantly and the restoration of RNF31 expression reversed the inhibitory effects of miR-503 on PCa cell proliferation and metastasis. These findings collectively indicated an oncogene role of RNF31 in PCa progression which can be regulated by miR-503, suggesting that RNF31 could serve as a potential prognostic biomarker and therapeutic target for PCa.

Prostate Specific Antigen as a Tumor Marker in Prostate Cancer: Biochemical and Clinical Aspects

In this chapter the use of prostate specific antigen (PSA) as a tumor marker for prostate cancer is discussed. The chapter provides an overview of biological and clinical aspects of PSA. The main drawback of total PSA (tPSA) is its lack of specificity for prostate cancer which leads to unnecessary biopsies. Moreover, PSA-testing poses a risk of overdiagnosis and subsequent overtreatment. Many PSA-based markers have been developed to improve the performance characteristics of tPSA. As well as different molecular subforms of tPSA, such as proPSA (pPSA) and free PSA (fPSA), and PSA derived kinetics as PSA-velocity (PSAV) and PSA-doubling time (PSADT). The prostate health index (phi), PSA-density (PSAD) and the contribution of non PSA-based markers such as the urinary transcripts of PCA3 and TMPRSS-ERG fusion are also discussed. To enable further risk stratification tumor markers are often combined with clinical data (e.g. outcome of DRE) in so-called nomograms. Currently the role of magnetic resonance imaging (MRI) in the detection and staging of prostate cancer is being explored.

Preclinical imaging of kallikrein-related peptidase 2 (hK2) in prostate cancer with a (111)In-radiolabelled monoclonal antibody, 11B6

Background

Prostate cancer is a leading cause of death in the male population of the western world. Human kallikrein-related peptidase 2 (hK2) is abundantly expressed in malignant prostatic tissue, and its gene, KLK2, is regulated by the androgen receptor. 11B6 is a murine IgG₁ monoclonal antibody directed against free human hK2. In this study, we performed a preclinical evaluation of ¹¹¹In-labelled 11B6 in mouse xenografts to investigate its potential in the clinical staging and assessment of metastatic prostate cancer.

Methods

11B6 was radiolabelled with ¹¹¹In through CHX-A″-DTPA chelation. In vivo biodistribution and uptake of ¹¹¹In-DTPA-11B6 were measured until 168 h post-injection in NMRI nude mice bearing subcutaneous LNCaP xenografts. The binding specificity to hK2 was evaluated by both in vivo competitive binding assays with excess non-labelled 11B6 and hK2-negative DU145 xenografts. SPECT/CT imaging of subcutaneous and intra-tibial LNCaP xenografts was used to visualize the tumours.

Results

Tumour uptake of ¹¹¹In-DTPA-11B6 in LNCaP xenografts was 19% ± 0.78%IA/g at 48 h, giving a tumour-to-blood ratio of 1.6, which increases to 2.4 at 1 week post-injection. Accumulation was low in other organs except for the salivary glands, which is probably the result of cross-reactivity with mouse kallikreins. Significantly lower tumour accumulation was observed in competitive assays and DU145 xenografts. SPECT/CT imaging could clearly visualize the subcutaneous and intra-tibial LNCaP xenografts.

Conclusions

Our study demonstrates the potential of ¹¹¹In-DTPA-11B6 for the detection of metastatic prostate cancer and monitoring anti-androgen therapy, as it exhibits an increased uptake and accumulation in viable tumour when compared to normal tissue. A humanised version of the 11B6 monoclonal antibody is currently under evaluation.

Electronic supplementary material

The online version of this article (doi:10.1186/s13550-014-0051-5) contains supplementary material, which is available to authorized users.

The C-terminal fragment of prostate-specific antigen, a 2331 Da peptide, as a new urinary pathognomonic biomarker candidate for diagnosing prostate cancer

Background and Objectives

Prostate cancer (PCa) is one of the most common cancers and leading cause of cancer-related deaths in men. Mass screening has been carried out since the 1990s using prostate-specific antigen (PSA) levels in the serum as a PCa biomarker. However, although PSA is an excellent organ-specific marker, it is not a cancer-specific marker. Therefore, the aim of this study was to discover new biomarkers for the diagnosis of PCa.

Materials and Methods

We focused on urine samples voided following prostate massage (digital rectal examination [DRE]) and conducted a peptidomic analysis of these samples using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MSⁿ). Urinary biomaterials were concentrated and desalted using CM-Sepharose prior to the following analyses being performed by MALDI-TOF/MSⁿ: 1) differential analyses of mass spectra; 2) determination of amino acid sequences; and 3) quantitative analyses using a stable isotope-labeled internal standard.

Results

Multivariate analysis of the MALDI-TOF/MS mass spectra of urinary extracts revealed a 2331 Da peptide in urine samples following DRE. This peptide was identified as a C-terminal PSA fragment composed of 19 amino acid residues. Moreover, quantitative analysis of the relationship between isotope-labeled synthetic and intact peptides using MALDI-TOF/MS revealed that this peptide may be a new pathognomonic biomarker candidate that can differentiate PCa patients from non-cancer subjects.

Conclusion

The results of the present study indicate that the 2331 Da peptide fragment of PSA may become a new pathognomonic biomarker for the diagnosis of PCa. A further large-scale investigation is currently underway to assess the possibility of using this peptide in the early detection of PCa.

Preferential autoimmune response in prostate cancer to cyclin B1 in a panel of tumor-associated antigens

Previous studies have demonstrated that sera from patients with prostate cancer (PCa) contain autoantibodies that react with tumor-associated antigens (TAAs). Autoantibodies to cyclin B1 and fourteen other TAAs were detected by enzyme-linked immunosorbent assay (ELISA) and Western blotting in 464 sera from patients with PCa, benign prostatic hyperplasia (BPH), and other controls. Autoantibodies to cyclin B1 were detected in 31.0% of sera from randomly selected patients with PCa versus 4.8% in sera with BPH. In the further analysis, 31.4% of sera from PCa patients at the early stage contained anti-cyclin B1 autoantibody, and even 29.4% of patients who had normal prostate-specific antigen (PSA) levels in their serum samples were observed anti-cyclin B1 positive. The cumulative positive rate of autoantibodies against seven selected TAAs (cyclin B1, survivin, p53, DFS70/LEDGFp75, RalA, MDM2, and NPM1) in PCa reached 80.5%, significantly higher than that in normal control sera. In summary, autoantibody to cyclin B1 might be a potential biomarker for the immunodiagnosis of early stage PCa, especially useful in patients with normal PSA level. This study further supports the hypothesis that a customized TAA array can be used for enhancing anti-TAA autoantibody detection, and it may constitute a promising and powerful tool for immunodiagnosis of PCa.

Prostate-specific antigen and other serum and urine markers in prostate cancer

Prostate-specific antigen (PSA) is one of the most widely used tumor markers, and strongly correlates with the risk of harboring from prostate cancer (PCa). This risk is visible already several years in advance but PSA has severe limitations for PCa detection with its low specificity and low negative predictive value. There is an urgent need for new biomarkers especially to detect clinically significant and aggressive PCa. From all PSA-based markers, the FDA-approved Prostate Health Index (phi) shows improved specificity over percent free and total PSA. Other serum kallikreins or sarcosine in serum or urine show more diverging data. In urine, the FDA-approved prostate cancer gene 3 (PCA3) has also proven its utility in the detection and management of early PCa. However, some aspects on its correlation with aggressiveness and the low sensitivity at very high values have to be re-examined. The detection of a fusion of the androgen regulated TMPRSS2 gene with the ERG oncogene (from the ETS family), which acts as transcription factor gene, in tissue of ~50% of all PCa patients was one milestone in PCa research. When combining the urinary assays for TMPRSS2:ERG and PCA3, an improved accuracy for PCa detection is visible. PCA3 and phi as the best available PCa biomarkers show an equal performance in direct comparisons.

A new model consists of intravesical prostatic protrusion, prostate volume and serum prostatic-specific antigen in the evaluation of prostate cancer

The Prostate-specific antigen (PSA) level is largely used to diagnose prostate cancer (PCa) in last decades. However, its specificity is low in patients with a PSA level ranging from 4.0 to 10.0 ng/ml. This study aims to define the correlation between intravesical prostatic protrusion (IPP) and PSA and to establish a new model to predict PCa. A total of 339 patients order than 45 years examined between October 2010 and June 2012 were enrolled. Eligible patients were recommended for transrectal ultrasonography (TRUS)-guided prostate biopsies after measuring total prostate volume (TPV), tranzisional zone volume (TZV) and IPP. The levels of total PSA (tPSA), free PSA (fPSA) were analyzed by using Hybritech calibrated Access tPSA and fPSA assays. A new mathematical model, named IPP removed PCa predicting score (IRPPS), consists of tPSA, TZV and IPP was established. The predictive accuracy of IRPPS, PSA density (PSAD), %PSA and tPSA were compared using receiver-operator characteristic (ROC) analysis. Eighty-six patients had PSA levels of 4.0-10.0 ng/ml. Twenty of them were diagnosed as PCa. Using ROC curves, the areas under the curve for IRPPS, PSAD and %PSA and tPSA were 0.786, 0.768 and 0.664 and 0.585, respectively. We suggested IPP grade had a significant relationship with serum tPSA levels. The predictive accuracy of IRPPS was higher than the other 3 indictors.

[-2]proPSA is an early marker for prostate cancer aggressiveness

BACKGROUND

The aim of the study was to evaluate the correlation between preoperative [-2]proPSA, the Gleason Score (GS) and the risk of non-organ-confined (NOC) disease in patients undergoing radical prostatectomy (RP).

METHODS

Beckman Coulter Access immunoassay was used to study serum specimens of 381 patients enrolled in a prostate cancer (PCa) early detection program. Inclusion criteria were three or more available serum specimens over 4 years before diagnosis. The values obtained were correlated with the GSs and pathological stages of specimens obtained at RP.

RESULTS

[-2]proPSA levels were significantly higher in the cancer group (n=208) than in the benign group (n=173). Already 4 years before diagnosis [-2]proPSA differed significantly between PCa and benign prostate in all measured time points, however, highest prediction value was 2 and 1 years before diagnosis (P<0.001). When stratified [-2]proPSA levels according to GS of RP specimens, [-2]proPSA was highest in patients with ≥GS8 and lowest in those with ≤GS6.The difference in [-2]proPSA values between GS≥8 and GS≤7 was highly significant (P<0.01) already 3 years before diagnosis. Investigating the correlation between extraprostatic extension and the preoperative [-2]proPSA levels we found preoperative [-2]proPSA values significantly higher in men with NOC PCa compared with organ-confined (OC) cancers.The highest predictive value of [-2]proPSA to differ between OC and extraprostatic extension was found 3 and 2 years before RP.

CONCLUSIONS

Patients with high [-2]proPSA levels in the years before cancer diagnosis are at a higher risk of having aggressive PCas. Thus, the [-2]proPSA should be included in the treatment decision-making for managing screen-detected PCa.

Prognostication of prostate cancer based on NUCB2 protein assessment: NUCB2 in prostate cancer

BACKGROUND

Nucleobindin 2 (NUCB2) protein, a novel oncoprotein, is overexpressed in breast cancer. To date, there have been no published data regarding the role of NUCB2 protein expression in prostate cancer (PCa). Therefore, this study was performed to investigate the correlations between NUCB2 protein expression and prognosis in patients with PCa.

METHODS

Through immunohistochemistry, NUCB2 protein expression was evaluated in 60 benign prostatic hyperplasia (BPH) specimens and 180 PCa specimens. The correlation of NUCB2 protein expression with clinicopathological parameters was assessed using χ2 analysis. Kaplan-Meier analysis and Cox proportional hazards regression models were used to investigate the correlation between NUCB2 protein expression and prognosis of PCa patients.

RESULTS

The immunohistochemistry results showed that the expression level of NUCB2 in PCa cases was significantly higher than that in BPH tissues (P < 0.001). Moreover, statistical analysis also showed that high NUCB2 protein expression was positively related to seminal vesicle invasion, lymph node metastasis, angiolymphatic invasion, higher Gleason score, biochemical recurrence (BCR), and higher preoperative prostate-specific antigen (PSA). Furthermore, it was also shown that patients with high NUCB2 protein expression had significantly poorer overall survival and BCR- free survival compared with patients with low expression of NUCB2 protein. Multivariate Cox regression analysis revealed that high NUCB2 protein expression level was an independent prognostic factor for overall survival and BCR-free survival of patients with PCa.

CONCLUSIONS

NUCB2 protein expression showed a strong association with the potencies of BCR and progression of PCa, and that may be applied as a novel biomarker for the prediction of BCR, and helpful for improving the diagnosis, prognosis and treatment of PCa.

Serologic autoantibodies as diagnostic cancer biomarkers--a review

Current diagnostic techniques used for the early detection of cancers are successful but subject to detection bias. A recent focus lies in the development of more accurate diagnostic tools. An increase in serologic autoantibody levels has been shown to precede the development of cancer disease symptoms. Therefore, autoantibody levels in patient blood serum have been proposed as diagnostic biomarkers for early-stage diagnosis of cancers. Their clinical application has, however, been hindered by low sensitivity, specificity, and low predictive value scores. These scores have been shown to improve when panels of multiple diagnostic autoantibody biomarkers are used. A five-marker biomarker panel has been shown to increase the sensitivity of prostate cancer diagnosis to 95% as compared with 12.2% for prostate-specific antigen alone. New potential biomarker panels were also discovered for lung, colon, and stomach cancer diagnosis with sensitivity of 76%, 65.4%, and 50.8%, respectively. Studies in breast and liver cancer, however, seem to favor single markers, namely α-2-HS-glycoprotein and des-γ-carboxyprothrombin with sensitivities of 79% and 89% for the early detection of the cancers. The aim of this review is to discuss the relevance of autoantibodies in cancer diagnosis and to outline the current methodologies used in the detection of autoantibodies. The review concludes with a discussion of the autoantibodies currently used in the diagnosis of cancers of the prostate, breast, lung, colon, stomach, and liver. A discussion of the potential future use of autoantibodies as diagnostic cancer biomarkers is also included in this review.

Quantified KLK15 gene expression levels discriminate prostate cancer from benign tumors and constitute a novel independent predictor of disease progression

BACKGROUND

Several transcript variants of the kallikrein-related peptidase 15 gene (KLK15) have been identified up to now. The classical KLK15 mRNA isoform encodes for a non-truncated, functional protein. Aberrant KLK15 expression is found in breast, ovarian, and prostate cancers. Our aim in this present study was the specific quantitative expression analysis of the classical KLK15 mRNA transcript in prostate tumors and the examination of its clinical significance in prostate cancer.

METHODS

We isolated total RNA from 150 prostate tissue specimens and, following cDNA synthesis, the expression of KLK15 classical mRNA transcript was measured via quantitative Real-Time PCR using the TaqMan® chemistry. HPRT1 was used as a reference gene, and the absolute quantification approach, through the incorporation of standard curves, was applied for the calculation of normalized KLK15 expression.

RESULTS

KLK15 expression levels were significantly upregulated in malignant compared to benign samples (P < 0.001). The discriminatory value of KLK15 was confirmed by ROC curve and logistic regression analysis (both P < 0.001). KLK15 was also associated with advanced pathological stage (P = 0.023). KLK15-positive prostate cancer patients presented significantly shorter progression-free survival intervals, determined by biochemical relapse (P = 0.006), compared to KLK15-negative ones. Multivariate Cox regression analysis revealed that KLK15 expression is an independent predictor of biochemical recurrence (HR = 3.36, P = 0.038).

CONCLUSIONS

The present study unravels the important role of quantified KLK15 classical mRNA expression levels as a novel biomarker helpful for the differential diagnosis and prognosis of prostate cancer patients.

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.

Systematic, evidence-based discovery of biomarkers at the NCI

In the past decade, biomarker discovery has become ubiquitous in cancer research. However, despite this interest in biomarker research, few newly-characterized biomarkers have emerged as clinically-used entities. Here, we review the current state of biomarker research in cancer and identify challenges that stall many biomarker discovery efforts. We outline a model for systematic biomarker discovery, exemplified by recent efforts in prostate cancer, in which bioinformatics plays a central role in identifying promising new candidate biomarkers. Finally, we review the role of the National Cancer Institute's Early Detection Research Network (EDRN) in biomarker studies and the importance of EDRN-led efforts to establish a research standard for more effective biomarker discovery efforts.

From prostate-specific antigen (PSA) to precursor PSA (proPSA) isoforms: a review of the emerging role of proPSAs in the detection and management of early prostate cancer

Despite the popularity of PSA blood testing for prostate cancer, there are a number of important limitations of this popular serum marker including the limited ability to accurately distinguish patients with and without prostate cancer and those who harbour an aggressive form of the disease. This is especially true when the total PSA is <10 ng/mL. Thus, significant efforts have been placed to find new serum markers that can help overcome these limitations. In this review article, we discuss the emerging role of the various precursor forms of PSA (proPSAs), with a special emphasis on [-2]proPSA in the detecion and management of early prostate cancer. The clinical utility of Prostate Health Index (phi) is also discussed. Despite the overall success of prostate-specific antigen (PSA) blood test, its use as a serum marker for prostate cancer has been limited due to the lack of specificity, especially in men presenting with a total PSA (tPSA) level of <10 ng/mL. PSA testing has also resulted in an increase in the number of patients being diagnosed with low-grade, potentially clinically insignificant prostate cancer. There is therefore an urgent need for new markers that can accurately detect as well as differentiate patients with aggressive vs unaggressive prostate cancer. In this review, we discuss the emerging role of precursor forms of PSA (proPSAs) and the Prostate Health Index (phi) measurement in the detection and management of early stage prostate cancer. A literature search was conducted using PubMed® to identify key studies. Studies to date suggest that [-2]proPSA, a truncated form of proPSA is the most cancer-specific form of all, being preferentially expressed in cancerous prostatic epithelium and being significantly elevated in serum of men with prostate cancer. There is evidence to suggest that %[-2]proPSA measurement ([-2]proPSA/free PSA [fPSA] × 100) improves the specificity of both tPSA and fPSA in detecting prostate cancer. phi incorporating [-2]proPSA, fPSA and tPSA measurements has also yielded promising results and appears superior to tPSA and fPSA in predicting those patients with prostate cancer. Increased phi levels also seem to preferentially detect patients harbouring more aggressive disease. Further studies in the form of large, multicentre, prospective trials with detailed health economic analyses are required to evaluate the true clinical applicability of these novel markers.

Kallikrein-related peptidase 4 gene (KLK4) in prostate tumors: quantitative expression analysis and evaluation of its clinical significance

BACKGROUND

Recently accumulating evidences underline the central role of the kallikrein-related peptidases family (KLKs) in prostate cancer (PCa) development and progression. The KLK4 is a prostate highly expressed gene under the transcriptional control of androgens, encoding for the KLK4 extracellular serine protease. The aim of this study is to investigate the expression status of KLK4 in PCa patients in order to reveal its utility in PCa establishment and clinical management.

METHODS

Prostatic tissue specimens were obtained from 60 PCa and 59 benign prostate hyperplasia (BPH) randomly chosen patients. Using a developed quantitative real-time RT-PCR method, KLK4 expression levels were determined in the specimens of the two patients' cohorts. Advance biostatistical analysis was completed to explore the clinical value of KLK4 expression in PCa and BPH patients.

RESULTS

PCa patients presented a statistically significant (P = 0.002) elevation, more than threefold, of the KLK4 transcripts compared to BPH ones. The KLK4 expression levels were also positive correlated with PCa patients' stage (P = 0.031) and preoperative prostate-specific antigen (PSA) serum concentrations (P < 0.001). ROC curve and logistic regression analysis revealed the significant (P = 0.002) and the independent (P = 0.044) clinical value of the KLK4 expression for the discrimination of PCa from BPH patients.

CONCLUSIONS

The KLK4 expression analysis reveals its up-regulation in PCa cells, which is significantly associated with the advanced stages of the disease and the patients' preoperative PSA serum levels. KLK4 quantification serves as an independent biomarker for the discrimination between the malignant and the benign nature of prostate tumors.

Between-method differences in prostate-specific antigen assays affect prostate cancer risk prediction by nomograms

BACKGROUND

To date, no published nomogram for prostate cancer (PCa) risk prediction has considered the between-method differences associated with estimating concentrations of prostate-specific antigen (PSA).

METHODS

Total PSA (tPSA) and free PSA were measured in 780 biopsy-referred men with 5 different assays. These data, together with other clinical parameters, were applied to 5 published nomograms that are used for PCa detection. Discrimination and calibration criteria were used to characterize the accuracy of the nomogram models under these conditions.

RESULTS

PCa was found in 455 men (58.3%), and 325 men had no evidence of malignancy. Median tPSA concentrations ranged from 5.5 μg/L to 7.04 μg/L, whereas the median percentage of free PSA ranged from 10.6% to 16.4%. Both the calibration and discrimination of the nomograms varied significantly across different types of PSA assays. Median PCa probabilities, which indicate PCa risk, ranged from 0.59 to 0.76 when different PSA assays were used within the same nomogram. On the other hand, various nomograms produced different PCa probabilities when the same PSA assay was used. Although the ROC curves had comparable areas under the ROC curve, considerable differences were observed among the 5 assays when the sensitivities and specificities at various PCa probability cutoffs were analyzed.

CONCLUSIONS

The accuracy of the PCa probabilities predicted according to different nomograms is limited by the lack of agreement between the different PSA assays. This difference between methods may lead to unacceptable variation in PCa risk prediction. A more cautious application of nomograms is recommended.

Exploratory study of a KLK2 polymorphism as a prognostic marker in prostate cancer

OBJECTIVES

An association of a single nucleotide polymorphism (SNP) of the KLK2 gene (rs198977; c.748C>T; R250W) with risk for developing prostate cancer has been observed. We evaluated the role of R250W SNP for prognosis in prostate cancer.

METHODS

The c.748C>T SNP was genotyped from blood DNA of 182 patients after completing initial cancer treatments. For evaluating prognosis of genotype groups, associations were performed with Gleason score (GS) and biochemical recurrence free survival (bRFS) in patients demonstrating PSA-recurrence after initial cancer therapy.

RESULTS

Overall distribution of the CC, CT and TT genotypes for the SNP was 48%, 44% and 8%, respectively. The distribution of high (8-10), moderate (5-7) and low (2-4) GS among the genotype groups was 17%, 74% and 9% for CC group compared to 25%, 74% and 1% for the CT/TT (P=0.04). Median bRFS time for CT/TT group was 36.5 months compared to 44.5 months for the CC group (P=0.16), while genotype groups combined with morphology revealed significantly different bRFS (P=0.004).

CONCLUSIONS

This exploratory analysis in prostate cancer patients revealed the W allele of the KLK2 R250W SNP to be less likely associated with low GS morphology. Further studies will be needed to confirm this observation in larger cohorts.

KLK15 is a prognostic marker for progression-free survival in patients with radical prostatectomy

In search of biomarkers for prostate cancer, we evaluated the expression of the human kallikrein-related peptidase KLK15 in samples of prostatic adenocarcinomas from radical prostatectomies. Twenty-five pairs of cancerous and adjacent normal prostatic tissue were selected by laser capture microdissection. The tissue was used for quantification of KLK15 mRNA by reverse-transcriptase polymerase chain reaction. Immunohistochemical expression of the KLK15 protein in 193 samples of prostatic adenocarcinoma was analysed in relation to clinicopathological parameters of the patients and disease progression. Expression of KLK15 correlated with the pathological tumour stage and Gleason score of the cases, both at mRNA and at protein level. While mRNA expression in the tumour was elevated, the protein level of KLK15 was reduced compared with adjacent normal tissue and to prostatic intraepithelial neoplasia. Univariate Kaplan-Meier analysis showed a significant association of dichotomised KLK15 levels with disease progression defined by prostate-specific antigen relapse (p = 0.001). Multivariate analysis according to the Cox proportional hazards regression model identified dichotomised KLK15 expression, corrected for the patient parameters age, preoperative prostate-specific antigen level, pathological tumour stage, Gleason score and surgical margin status, as an independent prognostic factor for poor outcome (inclusion model, hazard ratio 1.802, 95% confidence interval 1.037-3.132, p = 0.037). We suggest KLK15 as a new independent tumour marker for patients at risk for disease progression after radical prostatectomy.

Kallikrein-related peptidase genes as promising biomarkers for prognosis and monitoring of human malignancies

Tissue kallikrein (KLK1) and the kallikrein-related peptidase (KLK2-15) genes encode for a subgroup of 15 homologous secreted serine proteases possessing numerous physiological roles, such as the regulation of blood pressure, hormone processing and tissue remodeling. The expression of KLKs is detected in a broad spectrum of human tissues where it has been found to be regulated mainly by steroids hormones. The aberrant expression of KLKs, presented in many human malignancies, highlights the significance of this gene family for early diagnosis, prognosis and monitoring of cancer patients, as it is strongly emphasized by the routine use of PSA (KLK3) for prostate cancer management. Here, we review the presently known data regarding the role of KLKs as cancer biomarkers, giving emphasis on novel information about the subject.

Kallikreins on steroids: structure, function, and hormonal regulation of prostate-specific antigen and the extended kallikrein locus

The 15 members of the kallikrein-related serine peptidase (KLK) family have diverse tissue-specific expression profiles and putative proteolytic functions. The kallikrein family is also emerging as a rich source of disease biomarkers with KLK3, commonly known as prostate-specific antigen, being the current serum biomarker for prostate cancer. The kallikrein locus is also notable because it is extraordinarily responsive to steroids and other hormones. Indeed, at least 14 functional hormone response elements have been identified in the kallikrein locus. A more comprehensive understanding of the transcriptional regulation of kallikreins may help the field make more informed hypotheses about the physiological functions of kallikreins and their effectiveness as biomarkers. In this review, we describe the organization of the kallikrein locus and the structure of kallikrein genes and proteins. We also focus on the transcriptional regulation of kallikreins by androgens, progestins, glucocorticoids, mineralocorticoids, estrogens, and other hormones in animal models and human prostate, breast, and reproductive tract tissues. The interaction of the androgen receptor with androgen response elements in the promoter and enhancer of KLK2 and KLK3 is also summarized in detail. There is evidence that all kallikreins are regulated by multiple nuclear receptors. Yet, apart from KLK2 and KLK3, it is not clear whether all kallikreins are direct transcriptional targets. Therefore, we argue that gaining more detailed information about the mechanisms that regulate kallikrein expression should be a priority of future studies and that the kallikrein locus will continue to be an important model in the era of genome-wide analyses.

Natural and synthetic inhibitors of kallikrein-related peptidases (KLKs)

Including the true tissue kallikrein KLK1, kallikrein-related peptidases (KLKs) represent a family of fifteen mammalian serine proteases. While the physiological roles of several KLKs have been at least partially elucidated, their activation and regulation remain largely unclear. This obscurity may be related to the fact that a given KLK fulfills many different tasks in diverse fetal and adult tissues, and consequently, the timescale of some of their physiological actions varies significantly. To date, a variety of endogenous inhibitors that target distinct KLKs have been identified. Among them are the attenuating Zn(2+) ions, active site-directed proteinaceous inhibitors, such as serpins and the Kazal-type inhibitors, or the huge, unspecific compartment forming α(2)-macroglobulin. Failure of these inhibitory systems can lead to certain pathophysiological conditions. One of the most prominent examples is the Netherton syndrome, which is caused by dysfunctional domains of the Kazal-type inhibitor LEKTI-1 which fail to appropriately regulate KLKs in the skin. Small synthetic inhibitory compounds and natural polypeptidic exogenous inhibitors have been widely employed to characterize the activity and substrate specificity of KLKs and to further investigate their structures and biophysical properties. Overall, this knowledge leads not only to a better understanding of the physiological tasks of KLKs, but is also a strong fundament for the synthesis of small compound drugs and engineered biomolecules for pharmaceutical approaches. In several types of cancer, KLKs have been found to be overexpressed, which makes them clinically relevant biomarkers for prognosis and monitoring. Thus, down regulation of excessive KLK activity in cancer and in skin diseases by small inhibitor compounds may represent attractive therapeutical approaches.

Emerging drugs for prostate cancer

Prostate cancer mortality usually occurs as a result of castrate resistant disease. Many approaches are currently being evaluated to improve the treatment of this condition. These include drugs that induce androgen deprivation, that is, LHRH antagonists; more active or less toxic chemotherapy agents; immunologic approaches, including passive and active immunization; drugs that target the androgen receptor and/or androgen synthesis; drugs that target specific pathways, including tyrosine kinase inhibitors, angiogenesis inhibitors, endothelin antagonists and matrix metalloproteinase inhibitors; and antioxidants and cell cycle inhibitors. Many of these agents seem promising. The rationale, biologic activity and therapeutic results of these emerging drugs are reviewed.

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.

A new algorithm in patients with elevated and/or rising prostate-specific antigen level, minor lower urinary tract symptoms, and negative multisite prostate biopsies

Patients with elevated and/or rising prostate-specific antigen (PSA), minor lower urinary tract symptoms (LUTS), and no evidence for prostate cancer on (multiple) extended prostate biopsies are a regularly encountered problem in urological practice. Even now, patients are seen with no objective explanation of this persistent elevated and/or rising PSA. So far, many strategic proposals have been elaborated and published to deal with this specific population including the use of different PSA derivates; applying different biopsy schemes—strategies—biopsy target imaging; diagnostic use of prostate cancer genes; and many more. In this review, we propose a new algorithm in which an urodynamic evaluation should be included since bladder outlet obstruction (BOO) can be expected. Once BOO is confirmed, a transurethral resection of the prostate (TURP) can be offered to these patients. This procedure will result in subjective and biochemical improvement and allows extensive histological examination. Current literature was reviewed with regard to this specific population. This research was performed using the commercially available Medline online search tools and applying the following search terms: “diagnostic TURP”; “elevated PSA”; and “prostate biopsy”. Furthermore, subsequent reference search was executed on retrieved articles.

Benign prostatic hyperplasia-associated free prostate-specific antigen improves detection of prostate cancer in an artificial neural network

OBJECTIVES

To show discriminative power between patients with prostate cancer (PCa) and those with "no evidence of malignancy" using "benign" prostate-specific antigen (bPSA) and the new automated Access benign prostatic hyperplasia-associated (BPHA) research assay within a percent free PSA (%fPSA)-based artificial neural network (ANN) model.

METHODS

The sera from 287 patients with PCa and 254 patients with no evidence of malignancy were measured using the BPHA, total PSA (tPSA), and fPSA assays with Access immunoassay technology, with a 0-10 ng/mL tPSA range. Two ANN models with Bayesian regularization and leave-one-out validation using the 4 input parameters of tPSA, %fPSA, age, and prostate volume and 1 containing BPHA/tPSA were constructed and compared by receiver operating characteristic curve analysis.

RESULTS

The BPHA/tPSA-based ANN reached the significant greatest area under the receiver operating characteristic curve (AUC 0.81; P = .0004 and P = .0024) and best specificity (53.9% and 44.5%) compared with the ANN without BPHA/tPSA (AUC 0.77; specificity 50% and 40.6%) and %fPSA (AUC 0.77; specificity 40.9% and 27.2%) at 90% and 95% sensitivity, respectively. The AUCs for tPSA (0.58), BPHA (0.55), BPHA/fPSA (0.51), prostate volume (0.69), and BPHA/tPSA (0.69) were significantly lower.

CONCLUSIONS

Although BPHA as single marker or ratio to tPSA did not improve the diagnostic performance of %fPSA or tPSA, the incorporation of BPHA/tPSA into an ANN model increased the specificity compared with %fPSA by 13% and 17% at 90% and 95% sensitivity, respectively. Thus, the automated BPHA research assay might improve PCa detection when incorporating this new marker into an ANN.

Direct electrocatalytic mRNA detection using PNA-nanowire sensors

We report an electrochemical nucleic acids sensing system that exhibits high sensitivity and specificity when challenged with heterogeneous samples of RNA. The platform directly detects specific RNA sequences in cellular and clinical samples without any sample labeling or PCR amplification. The sensor features an electrode platform consisting of three-dimensional gold nanowires, and DNA or RNA hybridization is detected using an electrocatalytic reporter system. In this study, probes made of peptide nucleic acid (PNA) are used to detect a newly identified cancer biomarkera gene fusion recently associated with prostate cancer. The system is able to detect the fusion sequence with 100 fM sensitivity, and retains high sensitivity even in the presence of a large excess of non-complementary sequences. Moreover, the sensor is able to detect the fusion sequence in as little as 10 ng of mRNA isolated from cell lines or 100 ng total RNA from patient tissue samples. The PNA-nanowire nucleic acids sensor described is one of the first electrochemical sensors to directly detect specific mRNAs in unamplified patient samples.

A [-2]proPSA-based artificial neural network significantly improves differentiation between prostate cancer and benign prostatic diseases

BACKGROUND

The aim of this study was to combine the new automated Access [-2]proPSA (p2PSA) assay with a percent free PSA (%fPSA) based artificial neural network (ANN) or logistic regression (LR) model to enhance discrimination between patients with prostate cancer (PCa) and with no evidence of malignancy (NEM) and to detect aggressive PCa.

METHODS

Sera from 311 PCa patients and 275 NEM patients were measured with the p2PSA, total PSA (tPSA) and free PSA (fPSA) assays on Access immunoassay technology (Beckman Coulter, Fullerton, CA) within the 0-30 ng/ml tPSA range. Four hundred seventy-five patients (264 PCa, 211 NEM) had a tPSA of 2-10 ng/ml. LR models and leave-one-out (LOO) ANN models with Bayesian regularization by using tPSA, %fPSA, p2PSA/fPSA (%p2PSA), age and prostate volume were constructed and compared by receiver-operating characteristic (ROC) curve analysis.

RESULTS

The ANN and LR model each utilizing %p2PSA, %fPSA, tPSA and age, but without prostate volume, reached the highest AUCs (0.85 and 0.84) and best specificities (ANN: 62.1% and 45.5%; LR: 53.1% and 41.2%) compared with tPSA (22.7% and 11.4%) and %fPSA (45.5% and 26.1%) at 90% and 95% sensitivity. The %p2PSA furthermore distinguished better than tPSA and %fPSA between pT2 and pT3, and Gleason sum <7 and >or=7 PCa.

CONCLUSIONS

The automated p2PSA assay offers a new tool to improve PCa detection, and especially aggressive PCa detection. Incorporation of %p2PSA into an ANN and LR model further enhances the diagnostic accuracy to differentiate between malignant and non-malignant prostate diseases.

Multivariate gene expression analysis reveals functional connectivity changes between normal/tumoral prostates

BACKGROUND

Prostate cancer is a leading cause of death in the male population, therefore, a comprehensive study about the genes and the molecular networks involved in the tumoral prostate process becomes necessary. In order to understand the biological process behind potential biomarkers, we have analyzed a set of 57 cDNA microarrays containing approximately 25,000 genes.

RESULTS

Principal Component Analysis (PCA) combined with the Maximum-entropy Linear Discriminant Analysis (MLDA) were applied in order to identify genes with the most discriminative information between normal and tumoral prostatic tissues. Data analysis was carried out using three different approaches, namely: (i) differences in gene expression levels between normal and tumoral conditions from an univariate point of view; (ii) in a multivariate fashion using MLDA; and (iii) with a dependence network approach. Our results show that malignant transformation in the prostatic tissue is more related to functional connectivity changes in their dependence networks than to differential gene expression. The MYLK, KLK2, KLK3, HAN11, LTF, CSRP1 and TGM4 genes presented significant changes in their functional connectivity between normal and tumoral conditions and were also classified as the top seven most informative genes for the prostate cancer genesis process by our discriminant analysis. Moreover, among the identified genes we found classically known biomarkers and genes which are closely related to tumoral prostate, such as KLK3 and KLK2 and several other potential ones.

CONCLUSION

We have demonstrated that changes in functional connectivity may be implicit in the biological process which renders some genes more informative to discriminate between normal and tumoral conditions. Using the proposed method, namely, MLDA, in order to analyze the multivariate characteristic of genes, it was possible to capture the changes in dependence networks which are related to cell transformation.

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.