Biomarkers for prostate cancer

Photothermal visual sensing of alkaline phosphatase based on the etching of Au@MnO2 core-shell nanoparticles

Alkaline phosphatase (ALP), as a crucial enzyme involved in many physiological activities, is always used as one of the significant biomarkers in clinical diagnosis. Herein, a novel, simple, and effective photothermal quantitative method based on the etching of MnO₂-coated gold nanoparticles (Au@MnO₂ NPs) was established for ALP activity assay with a household thermometer-based visual readout. The photothermal effect of Au@MnO₂ NPs is much higher than that of MnO₂ NPs or Au NPs. The MnO₂ shell of Au@MnO₂ NPs can be etched by ascorbic acid, a product of ALP-catalyzed hydrolysis of 2-phospho-l-ascorbic acid. With the etching of Au@MnO₂ NPs, the photothermal conversion efficiency decreased gradually, causing the decrease of the temperature increment of the solutions by degrees. A household thermometer, instead of large-scale and professional instruments, was used as a signal reader to realize the visual quantitative detection. The photothermal platform was used successfully for the determination of ALP with a wide linear range from 2.0 to 50 U/L and a detection limit as low as 0.75 U/L. Moreover, the inhibition efficiency of sodium vanadate for ALP activity was investigated, proving the photothermal quantitative method will be a potential platform for screening enzyme inhibitors. Such a sensitive, facile, and low-cost sensing assay provides a new prospect to develop platforms for point-of-care testing.

Untargeted Metabolomics Study of Three Matrices: Seminal Fluid, Urine, and Serum to Search the Potential Indicators of Prostate Cancer

The simultaneous determination of metabolites from biological fluids may provide more accurate information about the current body condition. So far, the metabolomics approach has been successfully applied to study the mechanism of several disorders and to search for novel biomarkers. Urine and plasma are widely accepted matrices for the evaluation of several pathologies, while prostate cancer (CaP) development is still unknown. For this reason, an alternative matrix, the seminal fluid, was proposed to expand the knowledge about the CaP pathomechanism. The main aim of this study was to develop and optimize the sample preparation protocol to ensure the highest coverage of the metabolome of ejaculate samples. Parameters like the type and composition of the solvent mixture, time of extraction, and applied volume of the solvent were tested. The optimized method was applied for the untargeted metabolomics profiling of seminal fluid samples obtained from CaP patients. Moreover, urine and serum samples were also prepared for untargeted metabolomics analysis. Analyses were carried out with the use of two complementary analytical techniques: GC-EI-QqQ/MS and LC-ESI-TOF/MS. Finally, the metabolic signature of seminal fluid (n = 7), urine (n = 7), and plasma (n = 7) samples was compared. Furthermore, the hypothesis of the increased level of metabolites in ejaculate samples related to the CaP development was evaluated. The results indicated that the developed and optimized sample preparation protocol for seminal fluid may be successfully applied for metabolomics study. Untargeted analysis of ejaculate enabled to determine the following classes of compounds: fatty acids, sphingolipids, phospholipids, sugars, and their derivatives, as well as amino acids. Finally, a comparison of the three tested matrices was carried out. To our best knowledge, it is the first time when the metabolic profile of the three matrices, namely, urine, plasma, and seminal fluid, was compared. Based on the results, it can be pointed out that ejaculate comprises the metabolic signature of both matrices (polar compounds characteristic for urine, and non-polar ones present in plasma samples). Compared to plasma, semen samples revealed to have a similar profile; however, determined levels of metabolites were lower in case of ejaculate. In case of urine samples, compared to semen metabolic profiles, the levels of detected metabolites were decreased in the latter ones.

A novel non-enzymatic sensor for prostate cancer biomarker sensing based on electrocatalytic oxidation of sarcosine at nanostructured NiMn2O4 impregnated carbon paste electrode

This work addresses the electrocatalytic activity of a binary metal oxide catalyst of NiMn₂O₄ for electroxidation of sarcosine, the well-known prostate cancer biomarker. The nanocatalyst described was prepared via hydrothermal synthesis route, followed by calcination at 800 °C. Field emission scanning electron microscopy and X-ray diffraction were applied to obtain information about the material morphology and structure. A carbon paste electrode modified with nano-NiMn₂O₄ showed unique catalytic activity in sarcosine electroxidation which led to a significant rise in oxidation current (about four times) in comparison with the blank electrode. However, the carbon paste electrodes containing single oxides of NiO and Mn₂O₃ exhibited no considerable enhancement in sarcosine signal. The cyclic voltammetry results indicated that the Mn³⁺/Mn⁴⁺ couple was responsible for sarcosine oxidation, and NiO may enhance the content of Mn⁴⁺species in NiMn₂O₄ material. The carbon paste-based NiMn₂O₄ electrode was applied in the sensitive determination of sarcosine in the concentration range of 0.01-5.0 μM with the relative standard deviation of 3.49% (n = 5). The detection limit and quantification limit of the probe were determined to be 3.8 and 12 nM, respectively. The remarkable sensitivity and high selectivity of the method approved the sensor applicability in measurement of sarcosine content in urine samples.

Colorimetric paper-based sarcosine assay with improved sensitivity

This manuscript reports on a simple paper-based bienzymatic colorimetric assay for sarcosine as an important urinary biomarker of prostate cancer. All required assay reagents are pre-deposited on hydrophilic filter paper spots surrounded by a hydrophobic barrier. Sarcosine in the sample solution is selectively oxidized in the presence of sarcosine oxidase (SOx), resulting in the formation of hydrogen peroxide, which is subsequently detected through the horseradish peroxidase (HRP)-catalyzed conversion of the colorless indicator 3,3',5,5'-tetramethylbenzidine (TMB) into its blue-colored oxidation product. By the modification of the paper with positively charged poly(allylamine hydrochloride) (PAH), a linear response to sarcosine between 0 and 10 μM and a significant lowering of the limit of detection (LOD) (0.6 μM) compared to the unmodified paper substrate (12.6 μM) has been achieved. The improvement of the LOD was attributed to the fact that the presence of the polymer limits the enzyme-driven colorimetric reaction to the surface of the paper substrate, resulting in stronger color development. In experiments in artificial urine matrix, the bicarbonate anion was identified as an inhibitor of the colorimetric reaction. This inhibition was successfully eliminated through on-device sample pH adjustments with pH-buffer components pre-deposited onto assay devices. The LOD for sarcosine achieved in artificial urine matrix (2.5 μM) is below the 5 μM threshold value for this urinary biomarker required for diagnostic purposes. Finally, good selectivity over all 20 natural amino acids and satisfactory long-term storage stability of reagent-modified paper substrates at - 20 °C for a period of 50 days were confirmed.

A feasible self-assembled near-infrared fluorescence sensor for acid phosphatase detection and cell imaging

The single signal amplification strategy is significant for detecting various disease biomarkers but is restricted by its limited accuracy. The multi-signal and multi-mode methods have overcome this deficiency. Acid phosphatase (ACP) is an important intracellular enzyme but one-step cell imaging material-based probes are scarce for ACP. Herein, we designed a one-step self-assembled polymer probe using neutral red (NR), modified-(pyridoxal-5'-phosphate (PLP)) and Eu³⁺. The polymer exhibited non-emission and excellent stability. Upon the catalytic hydrolysis reaction of ACP, the polymer exhibited two strong fluorescence signals at 373 nm and 613 nm and an appreciable decline of absorbance at 395 nm. The probe has excellent selectivity and higher sensitivity with a limit of detection as low as 0.02 mU mL^-1. It possesses favorable biocompatibility and has been successfully used to detect and image intracellular ACP in several living cells.

Construction of a Carbon Dots/Cobalt Oxyhydroxide Nanoflakes Biosensing Platform for Detection of Acid Phosphatase

Because abnormal acid phosphatase (ACP) can disrupt the normal physiological processes, determination of ACP level is extremely important for early diagnosis, treatment, and prognostic evaluation of diseases. Herein, a fluorescence platform for monitoring ACP level was established based on the assembly of red-emitting carbon dots (RCDs) on cobalt oxyhydroxide (CoOOH) nanoflakes. RCDs displayed excellent water solubility, pH stability, salt resistance, and photobleaching resistance. Interestingly, the fluorescence of the RCDs assembled on the surface of the CoOOH nanoflakes could be quenched due to the energy transfer caused by the nanoflakes. However, the ascorbic acid (AA) produced by the hydrolysis of ascorbic acid-2-phosphate trisodium salt (AAP) catalyzed by ACP could quickly and effectively reduce CoOOH nanoflakes, leading to the fluorescence recovery of the RCDs. Therefore, an "off-on" biosensor platform for rapid, sensitive, and selective detection of ACP was constructed with a limit of detection of 0.25 mU/L. With the assistance of the biosensor, the level of ACP in human serum samples was evaluated, and the spike recovery values ranged from 94.0% to 104.5%.

A lysosome-targeted near-infrared fluorescent probe for imaging of acid phosphatase in living cells

Fluorescent probes for the detection of acid phosphatases (ACP) are important in the investigation of the pathology and diagnosis of diseases. We reported a lysosome-targeted near-infrared (NIR) fluorescent probe SHCy-P based on a novel NIR-emitting thioxanthene-indolium dye for the detection of ACP. The probe showed a long wavelength fluorescence emission at λ_em = 765 nm. Due to the ACP-catalyzed cleavage of the phosphate group in SHCy-P, the probe exhibited high selectivity and sensitivity for the 'turn-on' detection of ACP with a limit of detection as low as 0.48 U L^-1. The probe SHCy-P could also be used to detect and image endogenous ACP in lysosomes. In light of these prominent properties, we envision that SHCy-P will be an efficient optical imaging approach for investigating the ACP activity in disease diagnosis.

A novel fluorescence "turn off-on" nanosensor for sensitivity detection acid phosphatase and inhibitor based on glutathione-functionalized graphene quantum dots

In this paper, we developed a label-free and sensitive fluorescence sensor for acid phosphatase (ACP) and its inhibitor parathion-methyl (PM) detection based on glutathione-functionalized graphene quantum dots (GQDs@GSH). Upon addition of MnO₂ nanosheets, the fluorescence of GQDs@GSH could be efficiently quenched via a fluorescence resonance energy transfer. ACP could easily catalyze the hydrolysis of L-Ascorbic acid-2-phosphate (AAP) to ascorbic acid (AA), which could reduce MnO₂ nanosheets to Mn²⁺ in acidic environment, leading to dramatically increase of the fluorescence intensity of GQDs@GSH. Quantitative detection of ACP in a broad range from 0.1 to 9 mU mL^-1 with a detection limit of 0.027 mU mL^-1 could be achieved. The feasibility of the proposed sensor in real samples analysis was also studied and satisfactory results were obtained. Furthermore, the fluorescence assay strategy could also be used for the detection of parathion-methyl (PM) as ACP inhibitor.

Chitosan-stabilized platinum nanoparticles as effective oxidase mimics for colorimetric detection of acid phosphatase

Capping molecules on the surface of nanomaterials not only enhance the dispersion and stability of nanomaterials but also greatly facilitate their surface modification and biological applications. However, most capping molecules can severely block the active sites of the catalytic core, thereby decreasing the enzymatic activity of nanomaterial-based enzyme mimics. This work demonstrates the superiority of chitosan (Ch) as a capping molecule for synthesizing catalytic platinum nanoparticles (PtNPs). The experimental results show that Ch simultaneously exhibits an excellent stabilizing effect and enhances the oxidase-like activity of PtNPs. Kinetic studies indicate that Ch-PtNPs have a higher affinity for 3,3',5,5'-tetramethylbenzidine (TMB) than other kinds of oxidase mimics. Furthermore, the TMB chromogenic reaction catalyzed by Ch-PtNPs is found to be much faster in an acidic medium, thus adapting well to the optimal pH for acid phosphatase (ACP). Therefore, a novel colorimetric approach for ACP determination is developed for the first time, which is based on the Ch-PtNP-catalyzed oxidation of TMB, the inhibitory effect of ascorbic acid (AA) on the oxidase-like activity of Ch-PtNPs, and the ACP-catalyzed hydrolysis of AA 2-phosphate (AAP) into AA. The linear range for ACP is 0.25-2.5 U L^-1 and the limit of detection is measured to be 0.016 U L^-1. This new colorimetric method is utilized to detect ACP in real biological samples and to screen ACP inhibitors. We believe that these new PtNPs, which exhibit high colloidal stability, excellent catalytic performance, good biocompatibility, simple preparation, and easy modification, can be promising candidates for a broad range of applications in optical sensing, environmental monitoring, clinical diagnosis, and drug discovery.

Whole-genome gene expression analysis in urine samples of patients with prostate cancer and benign prostate hyperplasia

OBJECTIVE

There is an urgent need to find new biomarkers with higher specificity and sensitivity for using early detection of prostate cancer (PrCa) and reducing recurrent unnecessary biopsy rates, psychological and physical stress on the patient, and costs. Being noninvasive, urine-based tests might be suitable in routine practice. The aim of this study was to report the first whole-genome gene expression analysis in urine samples, as noninvasive method, that were obtained from PrCa, benign prostate hyperplasia (BPH), and control groups by using the microarray system from Turkey, to our knowledge.

METHODS

Whole-genome gene expression profiling was conducted in urine samples of 25 patients with PrCa, 24 patients with BPH, and 11 healthy males by using the Illumina Hi Scan microarray system.

RESULTS

The number of probes showing a significant change at the level of expression were 101 and 75 in PrCa-control and BPH-control comparison groups, respectively. Further, 51 of them were the same in both comparison groups. There was no significant change at the level of expression in PrCa-BPH comparison group.

CONCLUSION

This study revealed several candidate biomarkers for early diagnosis of PrCa and contributed to the literature by detecting the differences of gene expression profiles in urine samples of PrCa-control and BPH-control comparison groups using the microarray. However, further studies are needed in larger groups.

PSA and beyond: alternative prostate cancer biomarkers

BACKGROUND

The use of biomarkers for prostate cancer screening, diagnosis and prognosis has the potential to improve the clinical management of the patients. Owing to inherent limitations of the biomarker prostate-specific antigen (PSA), intensive efforts are currently directed towards a search for alternative prostate cancer biomarkers, particularly those that can predict disease aggressiveness and drive better treatment decisions.

METHODS

A literature search of Medline articles focused on recent and emerging advances in prostate cancer biomarkers was performed. The most promising biomarkers that have the potential to meet the unmet clinical needs in prostate cancer patient management and/or that are clinically implemented were selected.

CONCLUSIONS

With the advent of advanced genomic and proteomic technologies, we have in recent years seen an enormous spurt in prostate cancer biomarker research with several promising alternative biomarkers being discovered that show an improved sensitivity and specificity over PSA. The new generation of biomarkers can be tested via serum, urine, or tissue-based assays that have either received regulatory approval by the US Food and Drug Administration or are available as Clinical Laboratory Improvement Amendments-based laboratory developed tests. Additional emerging novel biomarkers for prostate cancer, including circulating tumor cells, microRNAs and exosomes, are still in their infancy. Together, these biomarkers provide actionable guidance for prostate cancer risk assessment, and are expected to lead to an era of personalized medicine.

Synthesis of functionalized fluorescent gold nanoclusters for acid phosphatase sensing

A novel and convenient one-pot but two-step synthesis of fluorescent gold nanoclusters, incorporating glutathione (GSH) and 11-mercaptoundecanoic acid (MUA) as the functionalized ligands (i.e. AuNCs@GSH/MUA), is demonstrated. Herein, the mixing of HAuCl4 and GSH in aqueous solution results in the immediate formation of non-fluorescent GSH-Au(+) complexes, and then a class of ∼2.6 nm GSH-coated AuNCs (AuNCs@GSH) with mild orange-yellow fluorescence after several days. Interestingly, the intense orange-red emitting ∼1.7 nm AuNCs@GSH/MUA can be synthesized within seconds by introducing an alkaline aqueous solution of MUA into the GSH-Au(+) complexes or AuNC@GSH solution. Subsequently, a reliable AuNC@GSH/MUA-based real-time assay of acid phosphatase (ACP) is established for the first time, inspired by the selective coordination of Fe(3+) with surface ligands of AuNCs, the higher binding affinity between the pyrophosphate ion (PPi) and Fe(3+), and the hydrolysis of PPi into orthophosphate by ACP. Our fluorescent chemosensor can also be applied to assay ACP in a real biological sample and, furthermore, to screen the inhibitor of ACP. This report paves a new avenue for synthesizing AuNCs based on either the bottom-up reduction or top-down etching method, establishing real-time fluorescence assays for ACP by means of PPi as the substrate, and further exploring the sensing applications of fluorescent AuNCs.

Near-infrared fluorescence probe for the determination of acid phosphatase and imaging of prostate cancer cells

In this paper, we developed a near-infrared mercaptopropionic acid (MPA)-capped CuInS2 quantum dot (QD) fluorescence probe for the detection of acid phosphatases (ACP), which is an important biomarker and indicator of prostate cancer. The fluorescence of CuInS2 QDs could be quenched by Cu(2+), and then the addition of adenosine-5'-triphosphate (ATP) could effectively turn on the quenched fluorescence due to the strong interaction between Cu(2+) and ATP. The ACP could catalyze the hydrolysis of ATP, which would disassemble the complex of Cu(2+)-ATP. Therefore, the recovered fluorescence could be quenched again by the addition of ACP. In our method, the limit of detection (LOD) is considerably low for ACP detection in solution. Using the CuInS2 QDs fluorescence probe, we successfully performed in vitro imaging of human prostate cancer cells.

Comparative study of trace elements in blood, scalp hair and nails of prostate cancer patients in relation to healthy donors

Prostate cancer is the most common fatal cancers in men, and exposure to toxic elements is the most important factor in the aetiology for prostate cancer. Selected elements (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were analyzed in the blood, scalp hair and nails of prostate cancer patients and counterpart healthy donors by atomic absorption spectrometry. Average concentrations of Cd, Mn, Ni and Pb were found to be significantly higher (p < 0.05) in the blood, scalp hair and nails of the patients compared with those of the healthy subjects who exhibited significantly higher concentrations of Zn. The correlation study revealed significantly diverse relationships of the elements in the blood, scalp hair and nails of the two donor groups. Variations in the elemental concentrations were also noted for various types of prostate cancer (adenocarcinoma, squamous cell carcinoma, transitional cell carcinoma and small cell carcinoma), as well as for different stages of the cancer. Multivariate apportionment of trace elements in the blood, scalp hair and nails of the patients was also significantly different than that in the healthy donors. The study evidenced considerably divergent variations in the elemental concentrations in prostate cancer patients in comparison with healthy subjects.

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.

Extracellular vesicles in prostate cancer: new future clinical strategies?

Prostate cancer (PCa) is the most common cancer—excluding skin tumors—in men older than 50 years of age. Over time, the ability to diagnose PCa has improved considerably, mainly due to the introduction of prostate-specific antigen (PSA) in the clinical routine. However, it is important to take into account that although PSA is a highly organ-specific marker, it is not cancer-specific. This shortcoming suggests the need to find new and more specific molecular markers. Several emerging PCa biomarkers have been evaluated or are being assessed for their potential use. There is increasing interest in the prospective use of extracellular vesicles as specific markers; it is well known that the content of vesicles is dependent on their cellular origin and is strongly related to the stimulus that triggers the release of the vesicles. Consequently, the identification of a disease-specific molecule (protein, lipid or RNA) associated with vesicles could facilitate their use as novel biological markers. The present review describes several in vitro studies that demonstrate the role of vesicles in PCa progression and several in vivo studies that highlight the potential use of vesicles as PCa biomarkers.

The role of prostatic inflammation biomarkers in the diagnosis of prostate diseases

Benign prostatic hyperplasia (BPH) and prostate cancer (PCa) are chronic conditions, which are hormone-dependent and epidemiologically associated with prostate inflammation. As a large number of studies have demonstrated, the stimulation of T-cells at the level of prostatic chronic inflammatory infiltrates is followed by stromal and epithelial cell proliferation. The aim of this review is to present the actual level of knowledge in the field of prostatic immune response and chronic inflammation, and to analyze the relationships between chronic inflammation and BPH/PCa. The most studied prostatic inflammation biomarkers detected in biological fluids are also presented, together with their potential roles in the diagnosis and prognosis of prostatic disease.

New serum biomarkers for prostate cancer diagnosis

BACKGROUND

Prostate-specific antigen (PSA) is currently used as a biomarker for diagnosis and management of prostate cancer (CaP). However, PSA typically lacks the sensitivity and specificity desired of a diagnostic marker.

OBJECTIVE

The goal of this study was to identify an additional biomarker or a panel of biomarkers that is more sensitive and specific than PSA in differentiating benign versus malignant prostate disease and/or localized CaP versus metastatic CaP.

METHODS

Concurrent measurements of circulating interleukin-8 (IL-8), Tumor necrosis factor-α (TNF-α) and soluble tumor necrosis factor-α receptors 1 (sTNFR1) were obtained from four groups of men: (1) Controls (2) with elevated prostate-specific antigen with a negative prostate biopsy (elPSA_negBx) (3) with clinically localized CaP and (4) with castration resistant prostate cancer.

RESULTS

TNF-α Area under the receiver operating characteristic curve (AUC = 0.93) and sTNFR1 (AUC = 0.97) were strong predictors of elPSA_negBx (vs. CaP). The best predictor of elPSA_negBx vs CaP was sTNFR1 and IL-8 combined (AUC = 0.997). The strongest single predictors of localized versus metastatic CaP were TNF-α (AUC = 0.992) and PSA (AUC = 0.963) levels.

CONCLUSIONS

The specificity and sensitivity of a PSA-based CaP diagnosis can be significantly enhanced by concurrent serum measurements of IL-8, TNF-α and sTNFR1. In view of the concerns about the ability of PSA to distinguish clinically relevant CaP from indolent disease, assessment of these biomarkers in the larger cohort is warranted.

Proteomics as a Quality Control Tool of Pharmaceutical Probiotic Bacterial Lysate Products

Probiotic bacteria have a wide range of applications in veterinary and human therapeutics. Inactivated probiotics are complex samples and quality control (QC) should measure as many molecular features as possible. Capillary electrophoresis coupled to mass spectrometry (CE/MS) has been used as a multidimensional and high throughput method for the identification and validation of biomarkers of disease in complex biological samples such as biofluids. In this study we evaluate the suitability of CE/MS to measure the consistency of different lots of the probiotic formulation Pro-Symbioflor which is a bacterial lysate of heat-inactivated Escherichia coli and Enterococcus faecalis. Over 5000 peptides were detected by CE/MS in 5 different lots of the bacterial lysate and in a sample of culture medium. 71 to 75% of the total peptide content was identical in all lots. This percentage increased to 87–89% when allowing the absence of a peptide in one of the 5 samples. These results, based on over 2000 peptides, suggest high similarity of the 5 different lots. Sequence analysis identified peptides of both E. coli and E. faecalis and peptides originating from the culture medium, thus confirming the presence of the strains in the formulation. Ontology analysis suggested that the majority of the peptides identified for E. coli originated from the cell membrane or the fimbrium, while peptides identified for E. faecalis were enriched for peptides originating from the cytoplasm. The bacterial lysate peptides as a whole are recognised as highly conserved molecular patterns by the innate immune system as microbe associated molecular pattern (MAMP). Sequence analysis also identified the presence of soybean, yeast and casein protein fragments that are part of the formulation of the culture medium. In conclusion CE/MS seems an appropriate QC tool to analyze complex biological products such as inactivated probiotic formulations and allows determining the similarity between lots.

Orexin expression in different prostate histopathologic examinations: Can it be a marker for prostate cancer? A preliminary result

OBJECTIVE

The aim of this study was to evaluate the expression of the orexin receptor in different prostate pathologies, including prostate adenocarcinoma, benign prostate hyperplasia and chronic prostatitis.

MATERIAL AND METHODS

A total of 90 patients (mean age 64.01±7.2 years) were enrolled in the study. The patients were divided into three groups of equal numbers based on their histopathologic findings: prostate cancer (Group 1), benign prostate hyperplasia (Group 2) and chronic prostatitis (Group 3). All the tissues were incubated with a primary antibody recognizing the Orexin receptor. The specific cytoplasmic immunoreactivity of the Orexin receptor was semiquantitatively scored for intensity and distribution based on a grading scale. The staining intensity and orexin expression were evaluated using Pearson χ(2) test.

RESULTS

A heterogeneous staining pattern of the Orexin receptor was observed between the groups. The expression rates were 90% (27/30) in Group 1, 53.3% (16/30) in Group 2 and 26.7% (8/30) in Group 3. While 5 patients (9.3%) in Group 1 showed strong staining, all samples from the other 2 groups showed only weak staining. There were significant differences in staining intensity between the three groups. The expression and distribution of the Orexin receptor was more widespread in Group 1 than in the other groups and was higher in patients with poorly differentiated malignancy. However, there was no significant difference based on Gleason score.

CONCLUSION

Orexin receptors are found in human prostate tissues and their expression is widespread in prostate cancer and in patients with a higher Gleason score. Therefore, we believe that Orexin immunoreactivity can be considered to be an indicator of poor prognosis and of poorly differentiated prostate cancer cases.

A robust automated measure of average antibody staining in immunohistochemistry images

Identifying and scoring cancer markers plays a key role in oncology, helping to characterize the tumor and predict the clinical course of the disease. The current method for scoring immunohistochemistry (IHC) slides is labor intensive and has inherent issues of quantitation. Although multiple attempts have been made to automate IHC scoring in the past decade, a major limitation in these efforts has been the setting of the threshold for positive staining. In this report, we propose the use of an averaged threshold measure (ATM) score that allows for automatic threshold setting. The ATM is a single multiplicative measure that includes both the proportion and intensity scores. It can be readily automated to allow for large-scale processing, and it is applicable in situations in which individual cells are hard to distinguish. The ATM scoring method was validated by applying it to simulated images, to a sequence of images from the same tumor, and to tumors from different patient biopsies that showed a broad range of staining patterns. Comparison between the ATM score and manual scoring by an expert pathologist showed that both methods resulted in essentially identical scores when applied to these patient biopsies. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Validation study of urinary metabolites as potential biomarkers for prostate cancer detection

Background: Urinary metabolomic profiles have recently drawn a lot of attention owing to a debate regarding their possible role as potential clinical markers for prostate cancer. In this study, levels of proline, kynurenine, uracil and glycerol-3-phosphate in 126 patients with genitourinary malignancies were analyzed using a validated method and compared with no evidence of malignancy. Results: The statistical results showed that these biomarkers cannot differentiate prostate cancer from no evidence of malignancy or from other related cancer types, such as bladder cancer. In addition, there was no significant difference in biomarker levels for T1 stages, T2 stages and Gleason scores <7, ≥7. From the correlation study, results showed/demonstrated that age or serum prostate-specific antigen levels do not influence these metabolite concentrations in urine. However, the strong correlation between these metabolites and urinary creatinine concentrations implies that their occurrence is mainly due to renal excretion. Conclusion: This detailed study shows that the aforementioned urinary metabolites are not reliable biomarkers for prostate cancer detection or for differentiating the aggressiveness of prostate cancer.

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

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

The diagnostic value of PCA3 gene-based analysis of urine sediments after digital rectal examination for prostate cancer in a Chinese population

Prostate cancer gene 3 (PCA3) encodes a prostate-specific mRNA that has shown promise as a prostate cancer (PCa) diagnostic tool and is detectable in prostate cancer cells shedding into urine after digital rectal examination (DRE). In our earlier studies, a tissue test for PCA3 appeared to have greater specificity for PCa. There, we performed a clinical evaluation of PCA3 mRNA assay in urine sediments after DRE enriched with prostate cells in a Chinese population. PCA3 mRNA was detected by real-time fluorescent quantitative reverse transcription-polymerase chain reaction (FQ-RT-PCR) in the urine sediments. PSA mRNA detected also by real-time FQ-RT-PCR was used to confirm the yield of prostate cells in the urine sediments beforehand and normalize PCA3 mRNA signals. The data were summarized in a receiver operating characteristic (ROC) curve to visualize the efficacy of ratio PCA3/PSA mRNA as a marker; sensitivity and specificity were calculated also. We also correlated the ratio PCA3/PSA mRNA to the biopsy results (including the presence or absence of malignancy and the Gleason score of the malignancy cases) and to the bone metastasis to evaluate its clinical value. The PCA3 mRNA expression (PCA3/PSA mRNA) in the PCa group was significantly higher than that in the BPH group. The AUC-ROC was 0.786 (95% CI: 0.683-0.889). When the cutoff value was set as 0.107, the sensitivity and specificity were 62.9% and 90.6%, respectively. The positive predictive value and negative predictive value of the PCA3 urine test was 78.6% and 81.7%, respectively. No significant correlation was found between urine PCA3 expression and Gleason score or bone metastasis. Results indicated the clinical usefulness of the PCA3/PSA mRNA of urine sediments after DRE as a molecular marker in the early diagnosis of prostate cancer, which appears to be highly specific for PCa. As a non-invasive and sample accessible assay, the PCA3/PSA mRNA may therefore be useful as an aid in the diagnosis of PCa.

Quantitative determination of sarcosine and related compounds in urinary samples by liquid chromatography with tandem mass spectrometry

The current prostate cancer (PCa) diagnosis, based on the blood prostate-specific antigen (PSA) level measurement, is not a precise science. The widely used PSA biomarker for PCa has poor sensitivity and specificity and often leads to false-negative and false-positive test results. Recently, sarcosine, proline, kynurenine, uracil, and glycerol 3-phosphate were found in higher concentrations in metastatic prostate cancer urine samples. By measuring all five of these metabolites, doctors may be better able to diagnose prostate cancer with high accuracy. However, there is no method reported for simultaneous detection of these compounds in urine samples. In this study, a novel method was developed to separate and quantify six urinary metabolites including creatinine in urine samples by using liquid chromatography/tandem mass spectrometry. Chromatographic separations of the analytes were carried out using a phenyl-hexyl column with 0.1% formic acid in water and acetonitrile, respectively, under a gradient program. The six metabolites were detected in the multiple reaction monitoring modes with the ESI-positive mode. The linear range of the analytes was from 0.003 to 40 μmol/L. The limit of detection was from 0.05 to 4 nmol/L, and the limit of quantification ranged from 3 to 20 nmol/L. The factors affecting the separation and quantification of the six metabolites, such as mobile-phase and MS conditions, were also investigated. The technique developed in this study is simple, fast, sensitive, and selective. It can be used for quantifying these six metabolites in urine samples for potential early cancer screening.

Eight-plex iTRAQ analysis of variant metastatic human prostate cancer cells identifies candidate biomarkers of progression: An exploratory study

BACKGROUND

Due to the heterogeneity in the biological behavior of prostate cancer, biomarkers that can reliably distinguish indolent from aggressive disease are urgently needed to inform treatment choices.

METHODS

We employed 8-plex isobaric Tags for Relative and Absolute Quantitation (iTRAQ), to profile the proteomes of two distinct panels of isogenic prostate cancer cells with varying growth and metastatic potentials, in order to identify novel biomarkers associated with progression. The LNCaP, LNCaP-Pro5, and LNCaP-LN3 panel of cells represent a model of androgen-responsive prostate cancer, while the PC-3, PC-3M, and PC-3M-LN4 panel represent a model of androgen-insensitive disease.

RESULTS

Of the 245 unique proteins identified and quantified (>or=95% confidence; >or=2 peptides/protein), 17 showed significant differential expression (>or=+/-1.5), in at least one of the variant LNCaP cells relative to parental cells. Similarly, comparisons within the PC-3 panel identified 45 proteins to show significant differential expression in at least one of the variant PC-3 cells compared with parental cells. Differential expression of selected candidates was verified by Western blotting or immunocytochemistry, and corresponding mRNA expression was determined by quantitative real-time PCR (qRT-PCR). Immunostaining of prostate tissue microarrays for ERp5, one of the candidates identified, showed a significant higher immunoexpression in pre-malignant lesions compared with non-malignant epithelium (P < 0.0001, Mann-Whitney U-test), and in high Gleason grade (4-5) versus low grade (2-3) cancers (P < 0.05).

CONCLUSIONS

Our study provides proof of principle for the application of an 8-plex iTRAQ approach to uncover clinically relevant candidate biomarkers for prostate cancer progression.

Status of transrectal ultrasound imaging of the prostate

PURPOSE

To describe the current and new developments in transrectal ultrasound (US) imaging of the prostate.

PATIENTS AND METHODS

Grayscale imaging of the prostate is the standard method for diagnostic evaluation and biopsy guidance. Color Doppler (CD) imaging, including CD and power Doppler US, allows for detection of macrovascularity and may therefore be helpful for assessment of prostatic blood flow. The use of US microbubbles for CD imaging and new contrast-specific techniques enable assessment of prostate microvascularity associated with prostate cancer (PCa). Recently, real-time elastography has been introduced to improve detection of cancer based upon changes in tissue stiffness.

RESULTS

Contrast-enhanced CD imaging has shown to enable PCa detection by performing targeted biopsies into suspicious areas. Comparisons between systematic and contrast-enhanced targeted biopsies have shown that the targeted approach detects more cancers and cancers with higher Gleason scores with a reduced number of biopsy cores. New microbubble-specific US techniques can improve sensitivity and specificity of US imaging for PCa detection. Real-time elastography has been demonstrated to be useful for the detection of PCa, and may further improve PCa staging.

CONCLUSIONS

The new US techniques seem to have the potential to improve PCa detection, and also PCa grading and staging. As these diagnostic methods improve, the ultimate hope is to eliminate biopsy in patients without cancer.

Identification of a novel prostate cancer biomarker, caveolin-1: Implications and potential clinical benefit

While prostate cancer is a common disease in men, it is uncommonly life-threatening. To better understand this phenomenon, tumor biologists have sought to elucidate the mechanisms that contribute to the development of virulent prostate cancer. The recent discovery that caveolin-1 (Cav-1) functions as an important oncogene involved in prostate cancer progression reflects the success of this effort. Cav-1 is a major structural coat protein of caveolae, specialized plasma membrane invaginations involved in multiple cellular functions, including molecular transport, cell adhesion, and signal transduction. Cav-1 is aberrantly overexpressed in human prostate cancer, with higher levels evident in metastatic versus primary sites. Intracellular Cav-1 promotes cell survival through activation of Akt and enhancement of additional growth factor pro-survival pathways. Cav-1 is also secreted as a biologically active molecule that promotes cell survival and angiogenesis within the tumor microenvironment. Secreted Cav-1 can be reproducibly detected in peripheral blood using a sensitive and specific immunoassay. Cav-1 levels distinguish men with prostate cancer from normal controls, and preoperative Cav-1 levels predict which patients are at highest risk for relapse following radical prostatectomy for localized disease. Thus, secreted Cav-1 is a promising biomarker in identifying clinically significant prostate cancer.

Identification of a novel prostate cancer biomarker, caveolin-1: Implications and potential clinical benefit

While prostate cancer is a common disease in men, it is uncommonly life-threatening. To better understand this phenomenon, tumor biologists have sought to elucidate the mechanisms that contribute to the development of virulent prostate cancer. The recent discovery that caveolin-1 (Cav-1) functions as an important oncogene involved in prostate cancer progression reflects the success of this effort. Cav-1 is a major structural coat protein of caveolae, specialized plasma membrane invaginations involved in multiple cellular functions, including molecular transport, cell adhesion, and signal transduction. Cav-1 is aberrantly overexpressed in human prostate cancer, with higher levels evident in metastatic versus primary sites. Intracellular Cav-1 promotes cell survival through activation of Akt and enhancement of additional growth factor pro-survival pathways. Cav-1 is also secreted as a biologically active molecule that promotes cell survival and angiogenesis within the tumor microenvironment. Secreted Cav-1 can be reproducibly detected in peripheral blood using a sensitive and specific immunoassay. Cav-1 levels distinguish men with prostate cancer from normal controls, and preoperative Cav-1 levels predict which patients are at highest risk for relapse following radical prostatectomy for localized disease. Thus, secreted Cav-1 is a promising biomarker in identifying clinically significant prostate cancer.

Advances in proteomic prostate cancer biomarker discovery

Prostate cancer is the most common non-cutaneous cancer in men in the United States. For reasons largely unknown, the incidence of prostate cancer has increased in the last two decades, in spite or perhaps because of a concomitant increase in serum prostate-specific antigen (PSA) screening. While PSA is acknowledged not to be an ideal biomarker for prostate cancer detection, it is however widely used by physicians due to lack of an alternative. Thus, the identification of a biomarker(s) that can complement or replace PSA represents a major goal for prostate cancer research. Screening complex biological specimens such as blood, urine, and tissue to identify protein biomarkers has become increasingly popular over the last decade thanks to advances in proteomic discovery methods. The completion of human genome sequence together with new development in mass spectrometry instrumentation and bioinformatics has been a major driving force in biomarker discovery research. Here we review the current state of proteomic applications as applied to various sample sources including blood, urine, tissue, and "secretome" for the purpose of prostate cancer biomarker discovery. Additionally, we review recent developments in validation of putative markers, efforts at systems biology approach, and current challenges of proteomics in biomarker discovery.

Analysis of peptides in biological fluids by LC-MS/MS

Urine contains large amounts of small peptides, which may represent a rich, yet largely unexplored, source of novel biomarkers for disease monitoring. This chapter describes detailed procedures for the analysis of urinary polypeptides by LC-MS/MS. Hundreds to thousands of small peptides (∼700 to ∼7000 Da) can be detected in urine with the described techniques. Extraction procedures, based on commercially available reagents, effectively remove interfering urinary organic and inorganic salts and neutral compounds, making this a robust and simple assay with the power to detect hundreds to thousands of polypeptides in urine. Analysis time is relatively short, making this protocol a valuable alternative to conventional proteomic techniques based on multidimensional separations. The methodology is therefore particularly useful when the aim is to analyse samples with sufficient depth and throughput so as to make it useful to compare large numbers of specimens. Procedures for enhancing quantitative and qualitative analysis of LC-MS/MS data are also detailed.

C-type natriuretic peptide in prostate cancer

C-type natriuretic peptide (CNP) is expressed in the male reproductive organs in pigs. To examine whether the human prostate also expresses the CNP gene, we measured CNP and N-terminal proCNP in prostate cancer tissue extracts and performed immunohistochemical biopsy staining. Additionally, proCNP-derived peptides were quantitated in plasma from patients with prostate cancer. Blood was collected from healthy controls and patients before surgery for localized prostate cancer. Tissue extracts were prepared from tissue biopsies obtained from radical prostatectomy surgery. N-terminal proCNP, proCNP (1-50) and CNP were measured in plasma and tissue extracts. Biopsies were stained for CNP-22 and N-terminal proCNP. Tissue extracts from human prostate cancer contained mostly N-terminal proCNP [median 5.3 pmol/g tissue (range 1.0-12.9)] and less CNP [0.14 pmol/g tissue (0.01-1.34)]. Immunohistochemistry demonstrated the presence of the peptides in prostatic epithelial cells. The N-terminal proCNP concentrations in plasma were marginally lower in patients with localized prostate cancer compared with control subjects [13.8 pmol/l (11.0-17.2) vs. 15.1 pmol/l (10.4-23.2), p=0.002] but not enough to justify the use of N-terminal proCNP as a cancer marker. Further research is needed to establish whether measurement of proCNP-derived peptides may offer clinical information.

[Molecular pathology as an necessity: its role in diagnostic and predictive pathology]

Individualized therapeutic regimes are almost exclusively based on the rapid developments in molecular pathology. Application of (additional) molecular pathological investigations may thus offer the unique opportunity to improve the classical morphologic diagnosis as well as to routinely evaluate the parameters ("biomarkers") required for therapeutic decision making. Pathologists are thus facing the cogent necessity to perform and develop molecular pathological investigations in high quality and to establish biobanks, as well as to adjust their specialist training accordingly in order to meet these requirements.

Molecular markers in prostate cancer. Part I: predicting lethality

Assessing the lethality of 'early,' potentially organ-confined prostate cancer (PCa) is one of the central controversies in modern-day urological clinical practice. Such cases are often considered for radical 'curative' treatment, although active surveillance may be equally appropriate for many men. Moreover, the balance between judicious intervention and overtreatment can be difficult to judge. The patient's age, comorbidities, family history and philosophy of self-health care can be weighed against clinical features such as the palpability of disease, the number and percentage of biopsy cores involved with the disease, histological grade, presenting prostate-specific antigen (PSA) and possible previous PSA kinetics. For many years, scientists and physicians have sought additional molecular factors that may be predictive for disease stage, progression and lethality. Usually, claims for a 'new' unique marker fall short of true clinical value. More often than not, such molecular markers are useful only in multivariate models. This review summarizes relevant molecular markers and models reported up to and including 2008.

[Molecular pathological identification of predictive biomarkers: a new task for diagnostic pathology]

The clinical management of cancer patients is still based to a great extent on the histological staging, grading, and tumor typing performed by the pathologist. As a result part of the patients are subjected to unnecessary treatment regimens with high rates of side effects and no advantages while another part of the patients could benefit from (adjuvant) therapies they would not routinely receive based on their tumor staging/grading. This situation has led to a search for so-called predictive biomarkers, which would allow better assessment of the clinical course, probability of metastases, and the efficacy of the treatment method, thus making it possible to individualize treatment for each cancer patient.

Contrast-enhanced ultrasound and prostate cancer; a multicentre European research coordination project

CONTEXT

Contrast-enhanced ultrasound is a real-time imaging technique with the capability of visualizing perfusion patterns. Since tumour growth is associated with changes in vascularisation, this modality is under research for imaging of various tumour types. Studies have shown promising results for the diagnosis of prostate cancer for various imaging techniques; however, the exact value of each technique is still unclear.

OBJECTIVE

To determine the value of contrast-enhanced ultrasound (CEUS) in the detection, localisation, and follow-up of treatment for prostate cancer.

EVIDENCE ACQUISITION

In the period 2002-2006, research in four European centres regarding CEUS of the prostate was coordinated in a combined program. This paper describes and combines the results of these studies.

EVIDENCE SYNTHESIS

Various techniques were developed and researched during the period of this program. Studies showed that prostate cancer could be visualized and localized in up to 78%. Visualization of the tumour enabled better detection; targeted biopsies lead to fewer biopsies per session without loss of detection rate. A combined approach offered the highest detection rate. CEUS could be used to visualize the effects of high-intensity focussed ultrasound and hormonal therapy for prostate cancer with success, and identified patients with an early relapse. Unfortunately, pretreatment evaluation could not identify the nonresponders beforehand.

CONCLUSIONS

This research project was a first step towards routine use of CEUS in the clinical detection and follow-up of prostate cancer; and new combined studies are initiated.