Emerging Biomarkers for the Diagnosis and Prognosis of Prostate Cancer

Identification of blood protein biomarkers associated with prostate cancer risk using genetic prediction models: analysis of over 140,000 subjects

Prostate cancer (PCa) brings huge public health burden in men. A growing number of conventional observational studies report associations of multiple circulating proteins with PCa risk. However, the existing findings may be subject to incoherent biases of conventional epidemiologic studies. To better characterize their associations, herein, we evaluated associations of genetically predicted concentrations of plasma proteins with PCa risk. We developed comprehensive genetic prediction models for protein levels in plasma. After testing 1308 proteins in 79 194 cases and 61 112 controls of European ancestry included in the consortia of BPC3, CAPS, CRUK, PEGASUS, and PRACTICAL, 24 proteins showed significant associations with PCa risk, including 16 previously reported proteins and eight novel proteins. Of them, 14 proteins showed negative associations and 10 showed positive associations with PCa risk. For 18 of the identified proteins, potential functional somatic changes of encoding genes were detected in PCa patients in The Cancer Genome Atlas (TCGA). Genes encoding these proteins were significantly involved in cancer-related pathways. We further identified drugs targeting the identified proteins, which may serve as candidates for drug repurposing for treating PCa. In conclusion, this study identifies novel protein biomarker candidates for PCa risk, which may provide new perspectives on the etiology of PCa and improve its therapeutic strategies.

68Ga-DOTA-NT-20.3 Neurotensin Receptor 1 PET Imaging as a Surrogate for Neuroendocrine Differentiation of Prostate Cancer

Prostate-specific membrane antigen (PSMA)-negative neuroendocrine prostate cancer (PCa) is a subtype of PCa likely to be lethal, with limited clinical diagnostic and therapeutic options. High expression of neurotensin receptor subtype 1 (NTR1) is associated with neuroendocrine differentiation of PCa, which makes NTR1 a potential target for neuroendocrine PCa. In this study, the NTR1-targeted tracer ⁶⁸Ga-DOTA-NT-20.3 was synthesized, and its affinity to androgen-dependent (LNCap) and androgen-independent (PC3) xenografts was determined. Methods: ⁶⁸Ga-DOTA-NT-20.3 was labeled using an automated synthesizer module, and its stability, labeling yield, and radiochemical purity were analyzed by radio-high-performance liquid chromatography. Receptor binding affinity was evaluated in NTR1-positive PC3 cells by a competitive binding assay. The biodistribution of ⁶⁸Ga-DOTA-NT-20.3 in vivo was evaluated in PC3 and LNCap xenografts by small-animal PET imaging. NTR1 expression was identified by immunohistochemistry and immunofluorescence evaluation. Results: ⁶⁸Ga-DOTA-NT-20.3 was synthesized successfully, with a yield of 88.07% ± 1.26%, radiochemical purity of at least 99%, and favorable stability. The NTR1 affinity (half-maximal inhibitory concentration) for ⁶⁸Ga-DOTA-NT-20.3 was 7.59 ± 0.41 nM. Small-animal PET/CT of PC3 xenograft animals showed high-contrast images with intense tumor uptake, which revealed specific NTR1 expression. The tumors showed significant radioactivity (4.95 ± 0.67 percentage injected dose per gram of tissue [%ID/g]) at 1 h, which fell to 1.95 ± 0.17 %ID/g (P < 0.01, t = 8.72) after specific blockage by neurotensin. LNCap xenografts had no significant accumulation (0.81 ± 0.06 %ID/g) of ⁶⁸Ga-DOTA-NT-20.3 at 1 h. In contrast, ⁶⁸Ga-PSMA-11 was concentrated mainly in LNCap xenografts (8.60 ± 2.11 %ID/g), with no significant uptake in PC3 tumors (0.53 ± 0.05 %ID/g), consistent with the in vitro immunohistochemistry findings. Biodistribution evaluation showed rapid clearance from the blood and main organs (brain, heart, lung, liver, muscle, and bone), with significantly high tumor-to-liver (4.41 ± 0.73) and tumor-to-muscle (12.34 ± 1.32) ratios at 60 min after injection. Conclusion: ⁶⁸Ga-DOTA-NT-20.3 can be efficiently prepared with a high yield and high radiochemical purity. Its favorable biodistribution and prominent NTR1 affinity make ⁶⁸Ga-DOTA-NT-20.3 a potential radiopharmaceutical for the detection of PSMA-negative PCa and identification of neuroendocrine differentiation.

Use of MS-GUIDE for identification of protein biomarkers for risk stratification of patients with prostate cancer

Background

Non-invasive liquid biopsies could complement current pathological nomograms for risk stratification of prostate cancer patients. Development and testing of potential liquid biopsy markers is time, resource, and cost-intensive. For most protein targets, no antibodies or ELISAs for efficient clinical cohort pre-evaluation are currently available. We reasoned that mass spectrometry-based prescreening would enable the cost-effective and rational preselection of candidates for subsequent clinical-grade ELISA development.

Methods

Using Mass Spectrometry-GUided Immunoassay DEvelopment (MS-GUIDE), we screened 48 literature-derived biomarker candidates for their potential utility in risk stratification scoring of prostate cancer patients. Parallel reaction monitoring was used to evaluate these 48 potential protein markers in a highly multiplexed fashion in a medium-sized patient cohort of 78 patients with ground-truth prostatectomy and clinical follow-up information. Clinical-grade ELISAs were then developed for two of these candidate proteins and used for significance testing in a larger, independent patient cohort of 263 patients.

Results

Machine learning-based analysis of the parallel reaction monitoring data of the liquid biopsies prequalified fibronectin and vitronectin as candidate biomarkers. We evaluated their predictive value for prostate cancer biochemical recurrence scoring in an independent validation cohort of 263 prostate cancer patients using clinical-grade ELISAs. The results of our prostate cancer risk stratification test were statistically significantly 10% better than results of the current gold standards PSA alone, PSA plus prostatectomy biopsy Gleason score, or the National Comprehensive Cancer Network score in prediction of recurrence.

Conclusion

Using MS-GUIDE we identified fibronectin and vitronectin as candidate biomarkers for prostate cancer risk stratification.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12014-022-09349-x.

A Review on the Current State and Future Perspectives of [99mTc]Tc-Housed PSMA-i in Prostate Cancer

Recently, prostate-specific membrane antigen (PSMA) has gained momentum in tumor nuclear molecular imaging as an excellent target for both the diagnosis and therapy of prostate cancer. Since 2008, after years of preclinical research efforts, a plentitude of radiolabeled compounds mainly based on low molecular weight PSMA inhibitors (PSMA-i) have been described for imaging and theranostic applications, and some of them have been transferred to the clinic. Most of these compounds include radiometals (e.g., ⁶⁸Ga, ⁶⁴Cu, ¹⁷⁷Lu) for positron emission tomography (PET) imaging or endoradiotherapy. Nowadays, although the development of new PET tracers has caused a significant drop in single-photon emission tomography (SPECT) research programs and the development of new technetium-99m (^99mTc) tracers is rare, this radionuclide remains the best atom for SPECT imaging owing to its ideal physical decay properties, convenient availability, and rich and versatile coordination chemistry. Indeed, ^99mTc still plays a relevant role in diagnostic nuclear medicine, as the number of clinical examinations based on ^99mTc outscores that of PET agents and ^99mTc-PSMA SPECT/CT may be a cost-effective alternative for ⁶⁸Ga-PSMA PET/CT. This review aims to give an overview of the specific features of the developed [^99mTc]Tc-tagged PSMA agents with particular attention to [^99mTc]Tc-PSMA-i. The chemical and pharmacological properties of the latter will be compared and discussed, highlighting the pros and cons with respect to [⁶⁸Ga]Ga-PSMA11.

Hepsin: a multifunctional transmembrane serine protease in pathobiology

Cell membrane-bound serine proteases are important in the maintenance of physiological homeostasis. Hepsin is a type II transmembrane serine protease highly expressed in the liver. Recent studies indicate that hepsin activates prohepatocyte growth factor in the liver to enhance Met signaling, thereby regulating glucose, lipid, and protein metabolism. In addition, hepsin functions in nonhepatic tissues, including the adipose tissue, kidney, and inner ear, to regulate adipocyte differentiation, urinary protein processing, and auditory function, respectively. In mouse models, hepsin deficiency lowers blood glucose, lipid, and protein levels, impairs uromodulin assembly in renal epithelial cells, and causes hearing loss. Elevated hepsin expression has also been found in many cancers. As a type II transmembrane protease, cell surface expression and zymogen activation are essential for hepsin activity. In this review, we discuss the current knowledge regarding hepsin biosynthesis, activation, and functions in pathobiology.

Phase-Regulated Sensing Mechanism of MoS2 Based Nanohybrids toward Point-of-Care Prostate Cancer Diagnosis

Alpha-methylacyl-CoA racemase (AMACR) has been proven to be consistently overexpressed in prostate cancer epitheliums, and is expected to act as a positive biomarker for the diagnosis of prostate carcinoma in clinical practice. Here, a strategy for specific determination of AMACR in real human serum by using an electrochemical microsensor system is presented. In order to implement the protocol, a self-organized nanohybrid consisting of metal nanopillars in a 2D MoS₂ matrix is developed as material for the sensing interface. The testing signal outputs are strongly enhanced with the presence of the nanohybrids owing to that the metal pillars provide an efficient mass difussion and electron transfer path to the MoS₂ film surface. Furthermore, the phase-regulated sensing mechanism over MoS₂ is noticed and demonstrated by density functional theory calculation and experiments. The explored MoS₂ based nanohybrids are employed for the fabrication of an electrochemical microsensor, presenting good linear relationship in both ng µL^-1 and pg µL^-1 ranges for AMACR quantification. The sampling analysis of human serum indicates that this microsensor has good diagnostic specificity and sensitivity toward AMACR. The proposed electrochemical microsensor system also demonstrates the advantages of convenience, cost-effectiveness, and disposability, resulting in a potential integrated microsystem for point-of-care prostate cancer diagnosis.

Downregulated circular RNA itchy E3 ubiquitin protein ligase correlates with advanced pathologic T stage, high lymph node metastasis risk and poor survivals in prostate cancer patients

OBJECTIVE

This study aimed to explore the correlation of circular RNA itchy E3 ubiquitin protein ligase (circ-ITCH) with pathological features as well as its predictive value on prognosis in prostate cancer patients.

METHODS

Three hundred and twenty-four patients with prostate cancer underwent radical prostatectomy were consecutively included in this retrospective study, and patients' specimens of tumor as well as paired adjacent tissues were collected for detection of circ-ITCH expression. Patients' baseline characteristics and survival data were obtained from follow-up records, and correlation of circ-ITCH with patients' pathological features and survival was determined.

RESULTS

Circ-ITCH expression was decreased in tumor tissue compared with paired adjacent tissues (P< 0.001), and it presented with good value in distinguishing tumor tissues from paired adjacent tissues with area under curve (AUC) of 0.812 (95%CI: 0.780-0.845). Circ-ITCH low expression was associated with advanced pathologic T stage (P= 0.002) and high risk of lymph node metastasis (P= 0.047) in prostate cancer patients. As for prognosis, patients with circ-ITCH high expression had longer disease-free survival (DFS) (P< 0.001) and overall survival (OS) (P< 0.001). Additionally, circ-ITCH (high vs. low) independently predicted better survival, while Gleason score (> 7 vs. ⩽ 7) and surgical margin status (positive vs. negative) independently predicted worse survival in prostate patients underwent radical prostatectomy.

CONCLUSIONS

Circ-ITCH is downregulated in prostate cancer tissues, and its low expression correlates with advanced pathologic T stage, high lymph mode metastasis risk and poor survival in prostate cancer patients underwent radical prostatectomy.

Untargeted Metabolomic Profile for the Detection of Prostate Carcinoma-Preliminary Results from PARAFAC2 and PLS-DA Models

Prostate-specific antigen (PSA) is the main biomarker for the screening of prostate cancer (PCa), which has a high sensibility (higher than 80%) that is negatively offset by its poor specificity (only 30%, with the European cut-off of 4 ng/mL). This generates a large number of useless biopsies, involving both risks for the patients and costs for the national healthcare systems. Consequently, efforts were recently made to discover new biomarkers useful for PCa screening, including our proposal of interpreting a multi-parametric urinary steroidal profile with multivariate statistics. This approach has been expanded to investigate new alleged biomarkers by the application of untargeted urinary metabolomics. Urine samples from 91 patients (43 affected by PCa; 48 by benign hyperplasia) were deconjugated, extracted in both basic and acidic conditions, derivatized with different reagents, and analyzed with different gas chromatographic columns. Three-dimensional data were obtained from full-scan electron impact mass spectra. The PARADISe software, coupled with NIST libraries, was employed for the computation of PARAFAC2 models, the extraction of the significative components (alleged biomarkers), and the generation of a semiquantitative dataset. After variables selection, a partial least squares-discriminant analysis classification model was built, yielding promising performances. The selected biomarkers need further validation, possibly involving, yet again, a targeted approach.

The role of fibromodulin in cancer pathogenesis: implications for diagnosis and therapy

Fibromodulin (FMOD) is known as one of very important extracellular matrix small leucine-rich proteoglycans. This small leucine-rich proteoglycan has critical roles in the extracellular matrix organization and necessary for repairing of tissue in many organs. Given that the major task of FMOD is the modulation of collagen fibrillogenesis. However, recently observed that FMOD plays very important roles in the modulation of a variety of pivotal biological processes including angiogenesis, regulation of TGF-β activity, and differentiation of human fibroblasts into pluripotent cells, inflammatory mechanisms, apoptosis and metastatic related phenotypes. Besides these roles, FMOD has been considered as a new tumor-related antigen in some malignancies such as lymphoma, leukemia, and leiomyoma. Taken together, these findings proposed that FMOD could be introduced as diagnostic and therapeutic biomarkers in treatment of various cancers. Herein, for first time, we highlighted the various roles of FMOD in the cancerous conditions. Moreover, we summarized the diagnostic and therapeutic applications of FMOD in cancer therapy.

Development of a glycoproteomic strategy to detect more aggressive prostate cancer using lectin-immunoassays for serum fucosylated PSA

Background

Prostate-specific antigen (PSA) is commonly used as a serum biomarker for the detection of prostate cancer. However, levels of PSA in serum do not reliably distinguish aggressive prostate cancer from non-aggressive disease. Therefore, there is an urgent need for biomarkers that can differentiate aggressive prostate cancers from non-aggressive phenotypes. Fucosylation is one of the glycosylation-based protein modifications. Previously we demonstrated increased levels of serum fucosylated PSA in patients with aggressive prostate cancer using lectin selection followed by PSA immunoassay.

Methods

We developed two lectin-immunoassays, Lens culinaris agglutinin (LCA) and Aleuria aurantia lectin (AAL) followed by clinical PSA immunoassay and investigated the levels of PSA and its fucosylated glycoforms in serum specimens from prostate cancer patients with different Gleason scores. First, we developed standard curves for lectins enrichment, which were applied to lectin-immunoassay for fucosylated PSA–LCA and PSA–AAL quantification in serum samples.

Results

Our results showed that both LCA- and AAL-immunoassays detected elevated fucosylated PSA and were correlated with higher Gleason scores but only AAL-immunoassay detected an increased percentage of fucosylated PSA in patient serum with higher Gleason scores.

Conclusion

We have developed quantitative lectin-immunoassays for serum fucosylated PSA. Our data demonstrated that fucosylated PSA–AAL, % fucosylated PSA–AAL and fucosylated PSA–LCA levels could be effective biomarkers to differentiate aggressive prostate cancer [especially Gleason 7 (4 + 3) or above] from non-aggressive disease. We believe that application of these lectin-immunoassays to a larger patient population is needed to evaluate the clinical utilities of fucosylated PSA using AAL–PSA and LCA–PSA for aggressive prostate cancer.

Recent progress on inhibitors of the type II transmembrane serine proteases, hepsin, matriptase and matriptase-2

Members of the type II transmembrane serine proteases (TTSP) family play a vital role in cell growth and development but many are also implicated in disease. Two of the well-studied TTSPs, matriptase and hepsin proteolytically process multiple protein substrates such as the inactive single-chain zymogens pro-HGF and pro-macrophage stimulating protein into the active heterodimeric forms, HGF and macrophage stimulating protein. These two proteases also have many other substrates which are associated with cancer and tumor progression. Another related TTSP, matriptase-2 is expressed in the liver and functions by regulating iron homoeostasis through the cleavage of hemojuvelin and thus is implicated in iron overload diseases. In the present review, we will discuss inhibitor design strategy and Structure activity relationships of TTSP inhibitors, which have been reported in the literature.

Dielectrophoresis-based microfluidic platforms for cancer diagnostics

The recent advancement of dielectrophoresis (DEP)-enabled microfluidic platforms is opening new opportunities for potential use in cancer disease diagnostics. DEP is advantageous because of its specificity, low cost, small sample volume requirement, and tuneable property for microfluidic platforms. These intrinsic advantages have made it especially suitable for developing microfluidic cancer diagnostic platforms. This review focuses on a comprehensive analysis of the recent developments of DEP enabled microfluidic platforms sorted according to the target cancer cell. Each study is critically analyzed, and the features of each platform, the performance, added functionality for clinical use, and the types of samples, used are discussed. We address the novelty of the techniques, strategies, and design configuration used in improving on existing technologies or previous studies. A summary of comparing the developmental extent of each study is made, and we conclude with a treatment of future trends and a brief summary.

The role of type II transmembrane serine protease-mediated signaling in cancer

Pericellular proteases have long been implicated in carcinogenesis. Previous research focused on these proteins, primarily as extracellular matrix (ECM) protein-degrading enzymes which allowed cancer cells to breach the basement membrane and invade surrounding tissue. However, recently, there has been a shift in the view of cell surface proteases, including serine proteases, as proteolytic modifiers of particular targets, including growth factors and protease-activated receptors, which are critical for the activation of oncogenic signaling pathways. Of the 176 human serine proteases currently identified, a subset of 17, known as type II transmembrane serine proteases (TTSPs). Many have been shown to be relevant to cancer progression since they were first identified as a family around the turn of the century. To this end, altered expression of TTSPs appeared as a trademark of several tumor types. However, the substrates and underlying signaling pathways remained unclear. Localization of these proteins to the cell surface places them in the unique position to mediate signal transduction between the cell and its surrounding environment. Many of the TTSPs have already been shown to play key roles in processes such as postnatal development, tissue homeostasis, and tumor progression, which share overlapping molecular mechanisms. In this review, we summarize the current knowledge regarding the role of the TTSP family in pro-oncogenic signaling.

Gene Expression Profiling of Prostate Cancer–Associated Genes Identifies Fibromodulin as Potential Novel Biomarker for Prostate Cancer

Background

The aim of this study was to evaluate the gene expression profiles of a set of prostate cancer–associated genes in prostate cancer cell lines, to determine their association with different cancer phenotypes and identify potential novel biomarkers for this disease.

Methods

Quantitative real-time PCR was used to determine the expression profiles of 21 prostate cancer–associated genes in the human prostate cancer cell lines PC-3 and LNCaP, using the nontumorigenic cell line PWR-1E as control cell line. Genes evaluated were ESM-1, SERPINE2, CLU, BGN, A2M, PENK, FMOD, CD81, DCN, TSPAN8, KBTBD10, F2RL1, TMSB4X, SNCG, CXXC5, FOXQ1, PDPN, SPN, CAV1, CD24 and KLK3. A potential biomarker from this set of genes, the FMOD gene, encoding the small leucine-rich proteoglycan fibromodulin, was selected for further evaluation in clinical samples from patients diagnosed with benign or malignant prostatic disease.

Results

Several of the evaluated genes showed significantly altered expression in the prostate cancer cell lines, compared with nontumorigenic PWR-1E cells. Further evaluation of FMOD transcript in prostate clinical samples from patients diagnosed with benign or malignant prostatic disease identified a significant difference in the expression levels of this proteoglycan between benign and malignant tissue (p<0.05).

Conclusions

A number of gene transcripts were differentially expressed by the cell lines assayed. Among them, FMOD was further evaluated in clinical samples and was found to be differentially expressed between benign and prostate cancer tissue. Further validation of FMOD transcript in a larger population is required to ascertain its usefulness as biomarker for prostate cancer.

Biomarkers for evaluation of prostate cancer prognosis

Prostate cancer, with a lifetime prevalence of one in six men, is the second cause of malignancy-related death and the most prevalent cancer in men in many countries. Nowadays, prostate cancer diagnosis is often based on the use of biomarkers, especially prostate-specific antigen (PSA) which can result in enhanced detection at earlier stage and decreasing in the number of metastatic patients. However, because of the low specificity of PSA, unnecessary biopsies and mistaken diagnoses frequently occur. Prostate cancer has various features so prognosis following diagnosis is greatly variable. There is a requirement for new prognostic biomarkers, particularly to differentiate between inactive and aggressive forms of disease, to improve clinical management of prostate cancer. Research continues into finding additional markers that may allow this goal to be attained. We here selected a group of candidate biomarkers including PSA, PSA velocity, percentage free PSA, TGFβ1, AMACR, chromogranin A, IL-6, IGFBPs, PSCA, biomarkers related to cell cycle regulation, apoptosis, PTEN, androgen receptor, cellular adhesion and angiogenesis, and also prognostic biomarkers with Genomic tests for discussion. This provides an outline of biomarkers that are presently of prognostic interest in prostate cancer investigation.

Proteomics analysis of urine reveals acute phase response proteins as candidate diagnostic biomarkers for prostate cancer

Despite the overall success of prostate specific antigen (PSA) in screening and detection of prostate cancer (PCa), its use has been limited due to the lack of specificity. The principal driving goal currently within PCa research is to identify non-invasive biomarker(s) for early detection of aggressive tumors with greater sensitivity and specificity than PSA. In this study, we focused on identification of non-invasive biomarkers in urine with higher specificity than PSA. We tested urine samples from PCa and benign prostatic hyperplasia (BPH) patients by 2-D DIGE coupled with MS and bioinformatics analysis. Statistically significant (p < 0.05), 1.8 fold variation or more in abundance, showed 41 spots, corresponding to 23 proteins. The Ingenuity Pathway Analysis showed significant association with the Acute Phase Response Signaling pathway. Nine proteins with differential abundances were included in this pathway: AMBP, APOA1, FGA, FGG, HP, ITIH4, SERPINA1, TF and TTR. The expression pattern of 4 acute phase response proteins differed from the defined expression in the canonical pathway. The urine levels of TF, AMPB and HP were measured by immunoturbidimetry in an independent validation set. The concentration of AMPB in urine was significantly higher in PCa while levels of TF and HP were opposite (p < 0.05). The AUC for the individual proteins ranged from 0.723 to 0.754. The combination of HP and AMBP yielded the highest accuracy (AUC = 0.848), greater than PSA. The proposed biomarker set is quickly quantifiable and economical with potential to improve the sensitivity and specificity of PCa detection.

Potential utility of cancer-specific biomarkers for assessing response to hormonal treatments in metastatic prostate cancer

Prostate cancer is the second leading cause of cancer death in men and there is an urgent clinical need to improve its detection and treatment. The introduction of prostate-specific antigen (PSA) as a biomarker for prostate cancer several decades ago represented an important step forward in our ability to diagnose this disease and offers the potential for earlier and more effective treatment. PSA measurements are now routinely conducted alongside digital rectal examination, with raised PSA levels leading to biopsy. PSA is also used to monitor disease and assess therapeutic response. However, there are some important limitations to its use, not least its lack of specificity for prostate cancer, and increased PSA screening may have resulted in overdiagnosis and overtreatment of early, low-risk prostate cancer. Therefore, there is a need for more specific and sensitive biomarkers for the diagnosis and monitoring of prostate cancer and treatment response; in particular, biomarkers of response to hormonal treatments in prostate cancer and predictive biomarkers to identify who is most likely to respond to these treatments. Here we review the current utilization of PSA and data on potentially more specific and sensitive biomarkers for the diagnosis and monitoring of prostate cancer: prostate cancer antigen 3 (PCA3) and the TMPRSS2-ERG fusion gene. A description of the design of an ongoing study of the 6-month extended release formulation of leuprorelin acetate (Eligard(®) 45 mg) will provide preliminary data on the potential utility of these new biomarkers for detecting therapeutic response after hormonal therapy.

Production of Nanobodies against Prostate-Specific Membrane Antigen (PSMA) Recognizing LnCaP Cells

Prostate cancer is the most common type of cancer in men. The antibody-mediated therapy for cancer treatment depends on the identification of selected molecular targets. The prostate-specific membrane antigen (PSMA) is a potential molecular target in prostate cancer and is abundantly expressed in this type of cancer. This study is aimed at designing and producing a recombinant PSMA epitope and a monoclonal nanobody with a high affinity toward the PSMA protein. A DNA fragment encoding the dominant epitopes of PSMA was designed, synthesized, and expressed in E. coli BL21 (DE3). A camel was immunized with the purified recombinant PSMA (rPSMA). Following mRNA isolation and cDNA synthesis, the variable fragment of heavy-chain antibodies (VHH) fragments were cloned and displayed on the surface of an M13 phage and used in sequential panning rounds. After phage ELISA and selection of colonies with the highest affinity, soluble nanobodies were produced and evaluated. Affinity of the nanobodies to rPSMA was estimated to be 3.5 × 10−7. Adherence of the purified anti-PSMA VHH was tested in cell-ELISA in the LnCaP and PC3 cell lines. VHH efficiently bound to LnCaP cells. The high specificity and affinity of this nanobody suggests its possible application as an effective tool in the diagnosis and treatment of prostate cancer.

Evaluation and prognostic significance of ACAT1 as a marker of prostate cancer progression

INTRODUCTION

Prostate cancer is the second leading cause of cancer-related death among men in North America. While a majority of prostate cancer cases remain indolent, subsets of patients develop aggressive cancers, which may lead to death. The current methods of detection include digital rectal examination and the serum PSA test. However, due to lack of specificity, neither of these approaches is able to accurately discriminate between indolent and aggressive cancer, which is why there is a need for additional prognostic factors. Previously, we identified enzymes of the ketogenic pathway, particularly ACAT1, to be elevated in aggressive prostate cancer.

METHODS

In the current study, we assessed the diagnostic and prognostic potential of ACAT1 by analyzing its expression using immunohistochemistry on a tissue microarray consisting of 251 clinically localized prostate cancer patients who have undergone radical prostatectomy.

RESULTS

Using quantitative digital imaging software, we found that ACAT1 expression was significantly greater in cancerous cores compared to adjacent benign cores (P < 0.0001), in Gleason score (GS) ≥8 cancers versus GS≤6 cancers (P < 0.0001), GS≥8 cancers versus GS7 cancers (P = 0.001), as well as pT3/pT4 versus pT2 cancers (P = 0.001). In addition, ACAT1 predicted biochemical recurrence in univariate (HR, 1.81, CI = 1.13-2.9, P = 0.0128), and multivariate models (HR, 1.69, CI = 1.01-2.81, P = 0.0431) including pre-operative PSA level, Gleason score and pathological stage. In univariate time-to-recurrence analysis, ACAT1 expression predicted recurrence in ERG negative cases (P = 0.0025), whereas ERG positive cases did not display any differences.

DISCUSSION

Taken together, these findings indicate that ACAT1 expression could serve as a potential prognostic marker in prostate cancer, specifically in differentiating indolent and aggressive forms of cancer.

Overexpression of LAPTM4B-35: a novel marker of poor prognosis of prostate cancer

Background

Lysosome-associated protein transmembrane 4b-35 (LAPTM4B-35) is a member of the mammalian 4-tetratransmembrane spanning protein superfamily, which is overexpressed in several solid malignancies. However, the expression of LAPTM4B-35 and its role in the progression of prostate cancer (PCa) is unknown. The aim of the present study was to investigate the LAPTM4B-35 expression in PCa and its potential relevance to clinicopathological variables and prognosis.

Methods

Immunohistochemistry was used to determine the expression of LAPTM4B-35 protein in 180 PCa tissues in comparison with 180 normal benign prostatic hyperplasia (BPH) specimens. The correlation between the expression of the LAPTM4B-35 protein and the clinicopathologic characteristics of patients with PCa was analyzed.

Results

Statistical analysis showed that LAPTM4B-35 expression was significantly elevated in PCa compared with the BPH controls. High LAPTM4B-35 staining was present in 71.11% of all the cases with PCa. The overexpression of LAPTM4B-35 was significantly associated with the lymph node metastasis, seminal vesicle invasion, PCa stage, higher Gleason score, higher preoperative PSA, and biochemical recurrence (BCR). The Kaplan-Meier survival analysis showed that the high expression of LAPTM4B-35 was related to the poor overall survival and BCR-free survival of patients with PCa. Multivariate Cox analysis showed that LAPTM4B-35 was an independent prognostic factor for both overall survival and BCR-free survival of patients with PCa.

Conclusions

Overexpression of LAPTM4B-35 may be associated with tumor progression and poor prognosis in PCa and thus may serve as a new molecular marker to predict the prognosis of PCa patients.

A Quest to Identify Prostate Cancer Circulating Biomarkers with a Bench-to-Bedside Potential

Prostate cancer (PCA) is a major health concern in current times. Ever since prostate specific antigen (PSA) was introduced in clinical practice almost three decades ago, the diagnosis and management of PCA have been revolutionized. With time, concerns arose as to the inherent shortcomings of this biomarker and alternatives were actively sought. Over the past decade new PCA biomarkers have been identified in tissue, blood, urine, and other body fluids that offer improved specificity and supplement our knowledge of disease progression. This review focuses on superiority of circulating biomarkers over tissue biomarkers due to the advantages of being more readily accessible, minimally invasive (blood) or noninvasive (urine), accessible for sampling on regular intervals, and easily utilized for follow-up after surgery or other treatment modalities. Some of the circulating biomarkers like PCA3, IL-6, and TMPRSS2-ERG are now detectable by commercially available kits while others like microRNAs (miR-21, -221, -141) and exosomes hold potential to become available as multiplexed assays. In this paper, we will review some of these potential candidate circulating biomarkers that either individually or in combination, once validated with large-scale trials, may eventually get utilized clinically for improved diagnosis, risk stratification, and treatment.

Molecular markers for prostate cancer in formalin-fixed paraffin-embedded tissues

Prostate cancer (PCa) is the most frequently diagnosed type of cancer in developed countries. The decisive method of diagnosis is based on the results of biopsies, morphologically evaluated to determine the presence or absence of cancer. Although this approach leads to a confident diagnosis in most cases, it can be improved by using the molecular markers present in the tissue. Both miRNAs and proteins are considered excellent candidates for biomarkers in formalin-fixed paraffin-embedded (FFPE) tissues, due to their stability over long periods of time. In the last few years, a concerted effort has been made to develop the necessary tools for their reliable measurement in these types of samples. Furthermore, the use of these kinds of markers may also help in establishing tumor grade and aggressiveness, as well as predicting the possible outcomes in each particular case for the different treatments available. This would aid clinicians in the decision-making process. In this review, we attempt to summarize and discuss the potential use of microRNA and protein profiles in FFPE tissue samples as markers to better predict PCa diagnosis, progression, and response to therapy.

Evaluation of prediction models for the staging of prostate cancer

Background

There are dilemmas associated with the diagnosis and prognosis of prostate cancer which has lead to over diagnosis and over treatment. Prediction tools have been developed to assist the treatment of the disease.

Methods

A retrospective review was performed of the Irish Prostate Cancer Research Consortium database and 603 patients were used in the study. Statistical models based on routinely used clinical variables were built using logistic regression, random forests and k nearest neighbours to predict prostate cancer stage. The predictive ability of the models was examined using discrimination metrics, calibration curves and clinical relevance, explored using decision curve analysis. The N = 603 patients were then applied to the 2007 Partin table to compare the predictions from the current gold standard in staging prediction to the models developed in this study.

Results

30% of the study cohort had non organ-confined disease. The model built using logistic regression illustrated the highest discrimination metrics (AUC = 0.622, Sens = 0.647, Spec = 0.601), best calibration and the most clinical relevance based on decision curve analysis. This model also achieved higher discrimination than the 2007 Partin table (ECE AUC = 0.572 & 0.509 for T1c and T2a respectively). However, even the best statistical model does not accurately predict prostate cancer stage.

Conclusions

This study has illustrated the inability of the current clinical variables and the 2007 Partin table to accurately predict prostate cancer stage. New biomarker features are urgently required to address the problem clinician’s face in identifying the most appropriate treatment for their patients. This paper also demonstrated a concise methodological approach to evaluate novel features or prediction models.

A Rac1/Cdc42 GTPase-specific small molecule inhibitor suppresses growth of primary human prostate cancer xenografts and prolongs survival in mice

Deregulated Rho GTPases Rac1 and Cdc42 have been discovered in various tumors, including prostate and Rac protein expression significantly increases in prostate cancer. The Rac and Cdc42 pathways promote the uncontrolled proliferation, invasion and metastatic properties of human cancer cells. We synthesized the novel compound AZA1 based on structural information of the known Rac1 inhibitor NSC23766. In the current study we investigated the effects of inhibition of these pathways by AZA1 on prostate tumorigenicity by performing preclinical studies using a xenograft mouse model of prostate cancer. In androgen-independent prostate cancer cells, AZA1 inhibited both Rac1 and Cdc42 but not RhoA GTPase activity in a dose-dependent manner and blocked cellular migration and proliferation. Cyclin D1 expression significantly decreased following Rac1/Cdc42 inhibition in prostate cancer cells. AZA1 treatment also down-regulated PAK and AKT activity in prostate cancer cells, associated with induction of the pro-apoptotic function of BAD by suppression of serine-112 phosphorylation. Daily systemic administration of AZA1 for 2 weeks reduced growth of human 22Rv1 prostate tumor xenografts in mice and improved the survival of tumor-bearing animals significantly. These data suggest a role of AZA1 in blocking Rac1/Cdc42-dependent cell cycle progression, cancer cell migration and increase of cancer cell apoptosis involving down-regulation of the AKT and PAK signaling pathway in prostate cancer cells. We therefore propose that a small-molecule inhibitor therapy targeting Rac1/Cdc42 Rho GTPase signaling pathways may be used as a novel treatment for patients with advanced prostate cancer.

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.

Prostate tissue characterization/classification in 144 patient population using wavelet and higher order spectra features from transrectal ultrasound images

In this work, we have proposed an on-line computer-aided diagnostic system called "UroImage" that classifies a Transrectal Ultrasound (TRUS) image into cancerous or non-cancerous with the help of non-linear Higher Order Spectra (HOS) features and Discrete Wavelet Transform (DWT) coefficients. The UroImage system consists of an on-line system where five significant features (one DWT-based feature and four HOS-based features) are extracted from the test image. These on-line features are transformed by the classifier parameters obtained using the training dataset to determine the class. We trained and tested six classifiers. The dataset used for evaluation had 144 TRUS images which were split into training and testing sets. Three-fold and ten-fold cross-validation protocols were adopted for training and estimating the accuracy of the classifiers. The ground truth used for training was obtained using the biopsy results. Among the six classifiers, using 10-fold cross-validation technique, Support Vector Machine and Fuzzy Sugeno classifiers presented the best classification accuracy of 97.9% with equally high values for sensitivity, specificity and positive predictive value. Our proposed automated system, which achieved more than 95% values for all the performance measures, can be an adjunct tool to provide an initial diagnosis for the identification of patients with prostate cancer. The technique, however, is limited by the limitations of 2D ultrasound guided biopsy, and we intend to improve our technique by using 3D TRUS images in the future.

The loss of the tumour-suppressor miR-145 results in the shorter disease-free survival of prostate cancer patients

BACKGROUND

Prostate cancer (PCa) is characterised by great heterogeneity of the disease progression rate. Tumours range from insignificant and not life threatening to high risk for relapse ones. Consequently, a large number of patients undergo unnecessary treatment. miR-145 is a well-documented tumour suppressor and its expression, which is regulated by the p53 pathway, has been found to be decreased in the majority of human malignancies. The aim of our study was to evaluate the clinical utility of miR-145 for the prognostication of PCa.

METHODS

Total RNA was isolated from 137 prostate tissue specimens obtained from 73 radical prostatectomy-treated PCa patients and 64 transurethral- or open prostatectomy-treated benign prostate hyperplasia (BPH) patients. Following polyadenylation and reverse transcription, miR-145 levels were determined by quantitative real-time PCR assay, using SNORD48 (RNU48) for normalisation purposes.

RESULTS

Downregulated miR-145 expression was found in PCa compared with BPH patients. The reduction of miR-145 expression in PCa was correlated with higher Gleason score, advanced clinical stage, larger tumour diameter and higher prostate-specific antigen (PSA) and follow-up PSA levels. In addition, higher risk for biochemical recurrence and significantly shorter disease-free survival (DFS) was found for the PCa patients expressing lower miR-145. Focusing on 'low- and intermediate-recurrence risk' PCa patients, miR-145 loss was revealed to be a reliable predictor of biochemical relapse and poor DFS independent from Gleason score, clinical stage, PSA and patients' age.

CONCLUSION

The loss of the tumour-suppressor miR-145 increases the risk for disease progression and predicts the poor survival of PCa patients.

Predictive factors of oncologic outcomes in patients who do not achieve undetectable prostate specific antigen after radical prostatectomy

PURPOSE

We identified factors predicting oncologic outcomes in cases of persistently detectable prostate specific antigen.

MATERIALS AND METHODS

We reviewed the charts of patients treated with radical prostatectomy between 1998 and 2011 at a total of 14 centers. Study inclusion criteria were radical prostatectomy for presumed localized prostate cancer, absent positive nodes and detectable prostate specific antigen, defined as prostate specific antigen 0.1 ng/ml or greater 6 weeks postoperatively. Of the 9,735 radical prostatectomy cases reviewed 496 (5.1%) were eligible for analysis. Predictive factors for oncologic outcomes were assessed in time dependent analyses using the Kaplan-Meier method and Cox regression models.

RESULTS

At 6 weeks prostate specific antigen was 0.1 to 6.8 ng/ml. Biochemical progression was noted in 74.4% of patients and clinical metastasis was noted in 5%. The 2 most powerful predictors of general salvage treatment (vs radiotherapy) were postoperative prostate specific antigen greater than 1 ng/ml (OR 3.46, p=0.032) and prostate specific antigen velocity greater than 0.2 ng/ml per year (HR 6.01, p=0.001). Positive prostate specific antigen velocity was the single factor that independently correlated with the risk of failed salvage therapy (HR 2.6, p=0.001). The 5-year disease-free survival rate was 81.0% in patients with stable or negative prostate specific antigen velocity compared with 58.4% in those with positive prostate specific antigen velocity (p<0.001).

CONCLUSIONS

Patients with detectable prostate specific antigen after radical prostatectomy have a poor biochemical outcome. We identified postoperative prostate specific antigen and prostate specific antigen velocity as independent predictors of progression and failed salvage treatment. In addition to pathological prognostic factors, these factors should be considered early to better stratify patients for adjuvant therapy.

Reliability of prostate-specific antigen-marker in determining biochemical failure during the first 2 years after external beam radiation therapy and hormone therapy in patients with non-operated prostate cancer

OBJECTIVES

The presence of prostate-specific antigen (PSA)-bounce after external beam radiation therapy (EBRT) and hormone therapy (HT) makes PSA an unreliable marker in determining PSA biochemical failure (PSA-BF) during the first 2 years after EBRT + HT in patients with non-operated prostate cancer (CaP). To determine the reliability of PSA-BF in predicting clinical outcomes, the Kamat definition, which does not consider PSA-BF during the first 24 months after EBRT, was tested against three other more frequently used methods (American Society of Radiation Oncology, Vancouver, and American Society of Radiation Oncology-Phoenix), which do. Secondly, their relative accuracies in predicting the clinical outcomes were also calculated.

MATERIALS AND METHODS

In January 2011, 193 consecutive CaPs, treated with radical EBRT + HT in our institution from 1999 to 2002, were retrospectively investigated. BF was calculated according to the Kamat definition against the other three above-mentioned methods. Each BF-free survival was analyzed in function of every clinical endpoint (clinical-failure-free survival, cause specific survival, and overall survival) using univariate and multivariate Cox regression analyses. The accuracy of each definition in predicting clinical relapse was also calculated and compared.

RESULTS

Only the Kamat BF definition had both a significant Cox hazard ratio, regarding clinical events or cancer deaths, and the best accuracy values in predicting clinical outcomes. Retrospective study design was the major limitation of the study.

CONCLUSIONS

Only the Kamat definition, which does not consider PSA-BF during the first 24 months after EBRT + HT, was shown to be a reliable predictor of clinical events. Thus, our results suggest that solely PSA-based BF should not be considered as a reliable surrogate endpoint during the first 24 months after EBRT + HT. Consequently, caution should be used in adopting rescue treatment without further work-up on an individual basis.

Dielectrophoretic Separation of Prostate Cancer Cells

Separation of cancer cells from other biological materials is significant for circulating tumor cell detection in cancer diagnosis and treatment. However, separation of one type of cancer cell from other types of cancer cells can be difficult, since they share similar morphology and biomarkers. In the present work, we have successfully manipulated and isolated LNCaP prostate cancer cells from HCT116 colorectal cancer cells, by dielectrophoresis (DEP) in a microfluidic platform in a continuous operation. In this cell sorter, the prostate cancer cells were treated as target cells and were deflected to a side channel from a main channel as they experienced a negative DEP force, when an AC electric field at the cross-over frequency of the HCT116 cells was supplied. This motion consequently led to the separation of the prostate cancer cells from the colorectal cancer cells. In this manuscript, we report the flow conditions, DEP spectra of the cancer cells and the isolation of LNCaP cells from HCT116 cells. The separation and enrichment factor have been investigated as well.

Combined application of information theory on laboratory results with classification and regression tree analysis: analysis of unnecessary biopsy for prostate cancer

BACKGROUND

The probability of a prostate cancer-positive biopsy result varies with PSA concentration. Thus, we applied information theory on classification and regression tree (CART) analysis for decision making predicting the probability of a biopsy result at various PSA concentrations.

METHODS

From 2007 to 2009, prostate biopsies were performed in 664 referred patients in a tertiary hospital. We created 2 CART models based on the information theory: one for moderate uncertainty (PSA concentration: 2.5-10 ng/ml) and the other for high uncertainty (PSA concentration: 10-25 ng/ml).

RESULTS

The CART model for moderate uncertainty (n=321) had 3 splits based on PSA density (PSAD), hypoechoic nodules, and age and the other CART for high uncertainty (n=160) had 2 splits based on prostate volume and percent-free PSA. In this validation set, the patients (14.3% and 14.0% for moderate and high uncertainty groups, respectively) could avoid unnecessary biopsies without false-negative results.

CONCLUSIONS

Using these CART models based on uncertainty information of PSA, the overall reduction in unnecessary prostate biopsies was 14.0-14.3% and CART models were simplified. Using uncertainty of laboratory results from information theoretic approach can provide additional information for decision analysis such as CART.

Identification of PCAG1 as a novel prostate cancer-associated gene

The aim of the present study was to identify a new prostate cancer‑associated gene and analyze its expression pattern. Comprehensive expression analysis of expressed sequence tags (ESTs) and microarray data and serial analysis of gene expression (SAGE) were conducted to screen in silico for candidate prostate cancer‑associated genes. Reverse transcription (RT)-PCR was performed to validate prostate cancer specificity. Prostate cancer‑associated gene 1 (PCAG1) was identified. The expression of PCAG1 mRNA and protein was evaluated in common human normal tissues, common malignant tumors, prostate adenocarcinoma and paired adjacent normal prostate tissues. An immunofluorescence assay was conducted to determine the subcellular location of PCAG1. PCAG1 mRNA was absent in the 15 pooled normal tissues (including normal prostate tissue) but registered at low levels in the spleen tissue (+). By contrast, PCAG1 mRNA was significantly higher than in the adjacent normal tissues in each of the 14 cases of prostate cancer, with ~50% scoring a high degree of expression (+++). Of the 32 types of normal tissues, 29 (including normal prostate tissue) demonstrated negative PCAG1 protein staining while the remaining tissues of the adrenal gland, parathyroid gland and liver expressed low levels. While 18/20 cases of prostate adenocarcinoma showed positive expression results, PCAG1 protein expression in the remaining types of cancer was scarce when present at all; only 41/380 other cancer cases demonstrated positive results at a low level. The most substantial PCAG1-positive expression results were identified by cytoplasmic staining in 36/38 prostate adenocarcinoma cases, with 10 cases showing high expression levels, 20 showing medium levels and 6 showing low levels. In the paired adjacent normal prostate tissues, only 3/38 cases showed low level positive staining, while 35/38 cases were negative. Immunofluorescent staining of the human prostate cancer PC3 cell line showed positive PCAG1 expression results in the mitochondria. The present study demonstrated that while PCAG1 mRNA was highly expressed in prostate cancer tissues, it was almost absent in all common normal tissues and paired adjacent normal prostate tissues. Furthermore, PCAG1 protein was also highly expressed in prostate cancer tissues, while few common normal tissues, other common malignant tumors and paired adjacent normal prostate tissues had even low levels of expression. Clarification of the function and transcriptional mechanism of PCAG1 may aid the elucidation of the mechanisms of carcinogenesis and progression of prostate cancer. The unique expression pattern of PCAG1 suggests its potential in certain clinical applications.

Use of PCA3 in detecting prostate cancer in initial and repeat prostate biopsy patients

BACKGROUND

The PCA3 urinary assay has shown promise in predicting the presence of prostate cancer. We evaluated the value of this test in patients undergoing initial and repeat prostate biopsy.

METHODS

PCA3 and PSA levels were obtained from 456 men with no known personal history of prostate cancer prior to prostate biopsy. Two hundred eighty-nine men underwent an initial prostate biopsy and 167 underwent a repeat prostate biopsy. PCA3 and PSA levels were compared to the prostate biopsy results.

RESULTS

PCA3 score was shown to be independent of prostate volume (P = 0.162) and PSA level (P = 0.959). PCA3 scores were significantly higher in patients with cancer on prostate biopsy compared to patients with negative biopsy results (P < 0.0001). In logistic regression, PCA3 showed a significantly higher AUC than PSA (0.726 vs. 0.512, P = 0.0001). This difference persisted when examining the initial biopsy subgroup, with PCA3 out-performing PSA (AUC 0.772 vs. AUC = 0.552, P < 0.0001), but not in the repeat biopsy subgroup (AUC = 0.605 vs. AUC = 0.500, P = 0.2488).

CONCLUSIONS

PCA3 was found to be a better predictor of prostate cancer than PSA in the total population as well as the initial biopsy population, but was not superior to PSA in the repeat biopsy population. Prostate 73: 48-53, 2013. © 2012 Wiley Periodicals, Inc.

Serum sarcosine increases the accuracy of prostate cancer detection in patients with total serum PSA less than 4.0 ng/ml

BACKGROUND

Sarcosine is reported to be a differential metabolite that is greatly increased during prostate cancer (PCa) progression. In this study, we assessed the role of serum sarcosine as a biomarker for PCa, as well as any association between sarcosine levels and clinical-pathological parameters.

METHODS

Sarcosine was measured by fluorometric assay in serum samples from 290 PCa patients and 312 patients with no evidence of malignancy (NEM), confirmed by 8-12 core prostate biopsies. Nonparametric statistical tests and receiver operating characteristics (ROC) analyses were performed to assess the diagnostic performance of sarcosine in different (prostate-specific antigen) PSA ranges.

RESULTS

ROC analyses in subjects with PSA < 4 ng/ml showed a higher predictive value of sarcosine (AUC = 0.668) versus total PSA (AUC = 0.535) (P = 0.03), whereas for the other two PSA ranges (4-10 ng/ml and >10 ng/ml), percent ratio of free to total PSA (%fPSA) showed a predictive superiority over sarcosine. Moreover, in patients with a PSA < 4 ng/ml, the percentage of low/intermediate-grade cancers was positively associated with sarcosine levels (P = 0.005). The specificities for serum sarcosine, %fPSA, PSA, and the logistic regression model at 95% sensitivity were 24.4, 3.41, 2.22, and 28.4%, respectively.

CONCLUSIONS

We provide evidence that serum sarcosine has a higher predictive value than tPSA and %fPSA in patients with PSA < 4 ng/ml. Moreover, sarcosine levels were significantly different in low grade versus high grade cancers in this subset of patients, suggesting that this marker may be a further tool not only for diagnosing PCa in normal PSA and abnormal DRE/TRUS patients but also for selecting candidates for non-aggressive therapies and active surveillance.

Tissue biomarkers for prostate cancer radiation therapy

Prostate cancer is the most common cancer and second leading cause of cancer deaths among men in the United States. Most men have localized disease diagnosed following an elevated serum prostate specific antigen test for cancer screening purposes. Standard treatment options consist of surgery or definitive radiation therapy directed by clinical factors that are organized into risk stratification groups. Current clinical risk stratification systems are still insufficient to differentiate lethal from indolent disease. Similarly, a subset of men in poor risk groups need to be identified for more aggressive treatment and enrollment into clinical trials. Furthermore, these clinical tools are very limited in revealing information about the biologic pathways driving these different disease phenotypes and do not offer insights for novel treatments which are needed in men with poor-risk disease. We believe molecular biomarkers may serve to bridge these inadequacies of traditional clinical factors opening the door for personalized treatment approaches that would allow tailoring of treatment options to maximize therapeutic outcome. We review the current state of prognostic and predictive tissue-based molecular biomarkers which can be used to direct localized prostate cancer treatment decisions, specifically those implicated with definitive and salvage radiation therapy.

Beyond PSA: the next generation of prostate cancer biomarkers

Since the introduction of serum prostate-specific antigen (PSA) screening 25 years ago, prostate cancer diagnosis and management have been guided by this biomarker. Yet, PSA has proven controversial as a screening assay owing to several inherent limitations. The next wave of prostate cancer biomarkers has emerged, introducing new assays in serum and urine that may supplement or, in time, replace PSA because of their higher cancer specificity. This expanding universe of biomarkers has been facilitated, in large part, by new genomic technologies that have enabled an unbiased look at cancer biology. Such efforts have produced several notable success stories that involve rapidly moving biomarkers from the bench to the clinic. However, biomarker research has centered on disease diagnostics, rather than prognosis and prediction, which would address disease management. The development of biomarkers to stratify risk of prostate cancer aggressiveness at the time of screening remains the greatest unmet clinical need in prostate cancer. We review the current state of prostate cancer biomarker research, including the PSA revolution, its impact on early cancer detection, the recent advances in biomarker discovery, and the future efforts that promise to improve clinical management of this disease.

Advances in membrane proteomics and cancer biomarker discovery: current status and future perspective

Membrane proteomic analysis has been proven to be a promising tool for identifying new and specific biomarkers that can be used for prognosis and monitoring of various cancers. Membrane proteins are of great interest particularly those with functional domains exposed to the extracellular environment. Integral membrane proteins represent about one-third of the proteins encoded by the human genome and assume a variety of key biological functions, such as cell-to-cell communication, receptor-mediated signal transduction, selective transport, and pharmacological actions. More than two-thirds of membrane proteins are drug targets, highlighting their immensely important pharmaceutical significance. Most plasma membrane proteins and proteins from other cellular membranes have several PTMs; for example, glycosylation, phosphorylation, and nitrosylation, and moreover, PTMs of proteins are known to play a key role in tumor biology. These modifications often cause change in stoichiometry and microheterogeneity in a protein molecule, which is apparent during electrophoretic separation. Furthermore, the analysis of glyco- and phosphoproteome of cell membrane presents a number of challenges mainly due to their low abundance, their large dynamic range, and the inherent hydrophobicity of membrane proteins. Under pathological conditions, PTMs, such as phosphorylation and glycosylation are frequently altered and have been recognized as a potential source for disease biomarkers. Thus, their accurate differential expression analysis, along with differential PTM analysis is of paramount importance. Here we summarize the current status of membrane-based biomarkers in various cancers, and future perspective of membrane biomarker research.

A panel of five circulating microRNAs as potential biomarkers for prostate cancer

BACKGROUND

Circulating microRNA (miRNAs) have been shown to have the potential as noninvasive diagnosis markers in several types of cancers. In this study, we investigated whether circulating miRNAs could be used in the diagnosis of prostate cancer (CaP) in a Chinese patient population.

METHODS

Illumina's Human v2 miRNA microarray was used to analyze miRNAs levels in a small set of patients [25 CaP, 17 benign prostatic hyperplasia (BPH)] in an effort to identify CaP-specific miRNAs. The identified miRNAs were further examined by quantitative real-time PCR (qRT-PCR) in the same small set of patients. After the training phase of screening and selecting, the candidate miRNAs were validated in a larger independent cohort (80 CaP, 44 BPH, and 54 healthy controls) with qRT-PCR in the verification phase.

RESULTS

Five miRNAs were confirmed by qRT-PCR analysis in validation sets. Receiver operating characteristic (ROC) curve analysis showed all 5 miRNAs had diagnostic value. More importantly, further principal component analysis indicated component 1 extracted from expression data of the 5 miRNAs could differentiate CaP from BPH and healthy controls with high diagnosis performance, with an AUC of 0.924 and 0.860, respectively.

CONCLUSIONS

Our data suggested that circulating miRNAs could serve as biomarkers for CaP, and compared to single miRNA, the 5 miRNAs panel can accurately discriminate CaP from BPH and healthy controls with high sensitivity and specificity, and therefore, combined with routine PSA test, these 5 CaP-specific miRNAs may help improve CaP diagnosis in clinical application.

Quantitative RT-PCR analysis of PSA and prostate-specific membrane antigen mRNA to detect circulating tumor cells improves recurrence-free survival nomogram prediction after radical prostatectomy

BACKGROUND

Circulating tumor cell (CTC) analysis is a potential new biomarker in prostate cancer. We hypothesize that quantitative detection of CTCs in patients pre- and post-radical prostatectomy (RP) using quantitative TaqMan® fluorogenic RT-PCR will improve the accuracy of the Kattan nomogram to predict the probability of recurrence-free survival (RFS) post-RP.

METHODS

Ninty-two patients who underwent RP between 2004 and 2009 had venous blood samples taken pre- (Day - 1) and post-operatively (Day + 7). We performed quantitative Taqman® RT-PCR to detect circulating prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) mRNA. We calculated both the logarithmic ratio of Day + 7/Day - 1 for PSA (PSAr) and PSMA (PSMAr) expression (log(Day+7/Day-1) ) and the Kattan nomogram predicted probability of disease recurrence for each patient. We then analyzed how the AUC-ROC analysis for the Kattan nomogram prediction alone (K) compared to the addition of the PSAr and PSMAr in predicting 5-year RFS.

RESULTS

The mean age (years), PSA (ng/ml), and follow-up (mo) was 65.1, 9.13, and 72, respectively. The AUCs for K, PSAr + K, and PSMAr + K were 0.752 (95%CI 0.620-0.860), 0.830 (95%CI 0.740-0.911), and 0.837 (95%CI 0.613-0.923), respectively (P = 0.03). The Kattan 5-year PSA RFS was 75%. The actual 5-year PSA RFS survival rate was 77%.

CONCLUSIONS

Data from modern quantitative RT-PCR to detect circulating prostate-derived PSA and PSM mRNA pre- and post-RP improves the accuracy of the Kattan nomogram to predict biochemical recurrence.

Proteomic profiling of androgen-independent prostate cancer cell lines reveals a role for protein S during the development of high grade and castration-resistant prostate cancer

Androgen deprivation constitutes the principal therapy for advanced and metastatic prostate cancers. However, this therapeutic intervention usually results in the transition to a more aggressive androgen-independent prostate cancer. The elucidation of molecular alterations during the progression to androgen independence is an integral step toward discovering more effective targeted therapies. With respect to identifying crucial mediators of this transition, we compared the proteomes of androgen-independent (PC3, DU145, PPC1, LNCaP-SF, and 22Rv1) and androgen-dependent (LNCaP and VCaP) and/or normal prostate epithelial (RWPE) cell lines using mass spectrometry. We identified more than 100 proteins that were differentially secreted in the androgen-independent cell lines. Of these, Protein S (PROS1) was elevated in the secretomes of all of the androgen-independent prostate cancer cell lines, with no detectable secretion in normal and androgen-dependent cell lines. Using quantitative PCR, we observed significantly higher (p < 0.05) tissue expression levels of PROS1 in prostate cancer samples, further indicating its importance in prostate cancer progression. Similarly, immunohistochemistry analysis revealed elevation of PROS1 in high grade prostate cancer (Gleason grade ≥ 8), and further elevation in castration-resistant metastatic prostate cancer lesions. We also observed its significant (p < 0.05) elevation in high grade prostate cancer seminal plasma samples. Taken together, these results show that PROS1 is elevated in high grade and castration-resistant prostate cancer and could serve as a potential biomarker of aggressive disease.