Characterization of the seminal plasma proteome in men with prostatitis by mass spectrometry

The correlation between human seminal plasma sialoproteins and ejaculate parameters

Sialic acids are negatively charged carbohydrates that are components of saccharide chains covalently linked to macromolecules. Sialylated glycoproteins are important for most biological processes, including reproduction, where they are associated with spermatogenesis, sperm motility, immune responses, and fertilization. Changes in the glycoprotein profile or sialylation in glycoproteins are likely to affect the quality of ejaculate. The aim of this study was to determine differences in the degree of sialylation between normozoospermic ejaculates and ejaculates with a pathological spermiogram using two lectins, Sambucus nigra (SNA) and Maackia amurensis (MAL II/MAA) recognizing α-2,6 or α-2,3 linkage of Sia to galactosyl residues. Our results show a close relationship between seminal plasma (SP) sialoproteins and the presence of anti-sperm antibodies in the ejaculate, apoptotic spermatozoa, and ejaculate quality. Using mass spectrometry, we identified SP sialoproteins such as, semenogelins, glycodelin, prolactin-inducible protein, lactotransferrin, and clusterin that are associated with spermatozoa and contribute to the modulation of the immune response and sperm apoptosis. Our findings suggest a correlation between the degree of SP glycoprotein sialylation and the existence of possible pathological states of spermatozoa and reproductive organs. Glycoproteins sialylation represents a potential parameter reflecting the overall quality of ejaculate and could potentially be utilised in diagnostics.

Investigation of Sperm and Seminal Plasma Candidate MicroRNAs of Bulls with Differing Fertility and In Silico Prediction of miRNA-mRNA Interaction Network of Reproductive Function

Simple Summary

The objective of this study was to identify differentially expressed (DE) sperm and seminal plasma microRNAs (miRNAs) in high- and low-fertile Holstein bulls (four bulls per group), integrate miRNAs to their target genes, and categorize target genes based on predicted biological processes. Out of 84 bovine-specific, prioritized miRNAs analyzed by RT-PCR, 30 were differentially expressed in high-fertile sperm and seminal plasma compared to low-fertile sperm and seminal plasma, respectively (p ≤ 0.05, fold regulation ≥5 magnitudes). Interestingly, expression levels of DE-miRNAs in sperm and seminal plasma followed a similar pattern. Highly scored integrated genes of DE-miRNAs predicted various biological and molecular functions, cellular process, and pathways. Further in silico analysis revealed categorized genes may have a plausible association with pathways regulating sperm structure and function, fertilization, and embryo and placental development. In conclusion, highly DE-miRNAs in bovine sperm and seminal plasma could be used as a tool for predicting reproductive functions. Since the identified miRNA-mRNA interactions were mostly based on predictions from public databases, the causal regulations of miRNA-mRNA and the underlying mechanisms require further functional characterization in future studies.

Abstract

Recent advances in high-throughput in silico techniques portray experimental data as exemplified biological networks and help us understand the role of individual proteins, interactions, and their biological functions. The objective of this study was to identify differentially expressed (DE) sperm and seminal plasma microRNAs (miRNAs) in high- and low-fertile Holstein bulls (four bulls per group), integrate miRNAs to their target genes, and categorize the target genes based on biological process predictions. Out of 84 bovine-specific, prioritized miRNAs analyzed by RT-PCR, 30 were differentially expressed in high-fertile sperm and seminal plasma compared to low-fertile sperm and seminal plasma, respectively (p ≤ 0.05, fold regulation ≥ 5 magnitudes). The expression levels of DE-miRNAs in sperm and seminal plasma followed a similar pattern. Highly scored integrated genes of DE-miRNAs predicted various biological and molecular functions, cellular process, and pathways. Further, analysis of the categorized genes showed association with pathways regulating sperm structure and function, fertilization, and embryo and placental development. In conclusion, highly DE-miRNAs in bovine sperm and seminal plasma could be used as a tool for predicting reproductive functions. Since the identified miRNA-mRNA interactions were mostly based on predictions from public databases, the causal regulations of miRNA-mRNA and the underlying mechanisms require further functional characterization in future studies.

Overview of seminal fluid biomarkers for the evaluation of chronic prostatitis: a scoping review

BACKGROUND

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a very common and difficult condition to evaluate, as it is a clinical diagnosis, without a measurable diagnostic "gold standard". The aim of this scoping review is to synthesize all the available data for seminal fluid biomarkers used to assess patients with CP/CPPS.

METHODS

A systematic search to identify all relevant publications was conducted on October 22, 2020 across five databases: Ovid Medline, Ovid EMBASE, PubMed, CCRT, and the CINAHL. Two independent authors screened all articles and extracted relevant data.

RESULTS

A total of 27 articles met the eligibility criteria. A majority of studies were case-control (15), with 6 observational cohorts and 6 comparative interventional studies. The total number of pooled patients included 585 patients with CP/CPPS (unspecified subtype), 371 patients with inflammatory CP/CPPS, 387 patients with non-inflammatory CP/CPPS, 354 patients with chronic bacterial prostatitis, and 432 healthy controls. Inflammatory seminal biomarkers were the most frequently studied, with IL6, IL8, TNFα and IL1β being the most promising candidates.

CONCLUSIONS

There are a number of very promising seminal biomarkers to help categorize and monitor therapies in CP/CPPS. Large multicentre studies using a shared protocol for measuring seminal biomarkers with the primary intention of biomarker validation are needed prior to clinical implementation. Identification of biomarker(s) will facilitate the etiological categorization of patients with chronic prostatitis and provide an objective framework to tailor specific therapies according to the biomarker family.

The Multifaceted Role of Aldehyde Dehydrogenases in Prostate Cancer Stem Cells

Cancer stem cells (CSCs) are the only tumor cells possessing self-renewal and differentiation properties, making them an engine of tumor progression and a source of tumor regrowth after treatment. Conventional therapies eliminate most non-CSCs, while CSCs often remain radiation and drug resistant, leading to tumor relapse and metastases. Thus, targeting CSCs might be a powerful tool to overcome tumor resistance and increase the efficiency of current cancer treatment strategies. The identification and isolation of the CSC population based on its high aldehyde dehydrogenase activity (ALDH) is widely accepted for prostate cancer (PCa) and many other solid tumors. In PCa, several ALDH genes contribute to the ALDH activity, which can be measured in the enzymatic assay by converting 4, 4-difluoro-4-bora-3a, 4a-diaza-s-indacene (BODIPY) aminoacetaldehyde (BAAA) into the fluorescent product BODIPY-aminoacetate (BAA). Although each ALDH isoform plays an individual role in PCa biology, their mutual functional interplay also contributes to PCa progression. Thus, ALDH proteins are markers and functional regulators of CSC properties, representing an attractive target for cancer treatment. In this review, we discuss the current state of research regarding the role of individual ALDH isoforms in PCa development and progression, their possible therapeutic targeting, and provide an outlook for the future advances in this field.

Identification of Altered Proteins in the Plasma of Rats With Chronic Prostatic Inflammation Induced by Estradiol Benzoate and Sex Hormones

The cause of nonbacterial chronic prostatitis is unknown, yet its prevalence accounts for more than 90% of all prostatitis cases. Whole blood, plasma, and serum have been used to identify prostate cancer biomarkers; however, few studies have performed protein profiling to identify prostatitis biomarkers. The purpose of this study was to identify protein biomarkers altered by chronic prostatitis. To perform the study, we chemically induced chronic prostate inflammation in Sprague Dawley rats using estradiol benzoate (EB), testosterone (T), and estradiol (E) and then examined protein levels in their plasma. Plasma was collected on postnatal days (PNDs) 90, 100, 145, and 200; plasma proteins were profiled using liquid chromatography-tandem mass spectrometry. Chronic inflammation was observed in the rat prostate induced with EB on PNDs 1, 3, and 5. Rats then were dosed with T+E during PNDs 90-200 via subcutaneous implants. We identified time-specific expression for several proteins (i.e., CFB, MYH9, AZGP1). Some altered proteins that were expressed in the prostate (i.e., SERPINF1, CTR9) also were identified in the rat plasma in the EB+T+E group on PNDs 145 and 200. These findings suggest that the identified proteins could be used as biomarkers of chronic prostatitis. Further studies are needed to verify the results in human samples.

Seminal Plasma Proteomic Biomarkers of Oxidative Stress

The prevalence of idiopathic male infertility is high, up to 75% of patients with abnormal sperm parameters. Hence, the research of its causes is mandatory. Oxidative stress (OS) can be responsible for male infertility in 30–80% of cases. In recent years, seminal plasma (SP) proteomics has developed as a useful tool to provide biomarkers of specific diseases. This systematic review aims to collect the available evidence on the changes of SP proteome in patients exposed to OS to provide possible SP biomarkers of sperm OS. To accomplish this, the following keyterms “seminal fluid proteome”, “seminal plasma proteome”, “oxidative stress”, and “sperm oxidative stress” were used and 137 records were found. Among these, 17 were finally included. Nine proteins involved with OS were found overexpressed in patients with OS. Twenty-three proteins were found differentially expressed in patients with clinical conditions associated with OS, such as varicocele, male accessory gland infection/inflammation, cigarette smoke, and obesity. These proteins do not seem to overlap among the clinical conditions taken into account. We speculate that specific SP proteins may mediate OS in different clinical conditions. Altogether, these results suggest that proteomics could help to better understand some of the molecular mechanisms involved in the pathogenesis of infertility. However, further studies are needed to identify potential biomarkers of male infertility with valuable clinical significance.

The Vehicle Determines the Destination: The Significance of Seminal Plasma Factors for Male Fertility

Of all human infertility cases, up to 50% show contributing factors leading to defects in the male reproductive physiology. Seminal plasma (SP) is the biological fluid derived from the male accessory sex gland which carries spermatozoa passing throughout the male and female reproductive tract during ejaculation. It contains a complicated set of heterogeneous molecular structures, including proteins, cell-free nucleic acid (DNA, microRNA and LncRNA), and small-molecule metabolites as well as inorganic chemicals (ions). For a long time, the substantial significance of seminal plasma factors’ functions has been underestimated, which is restricted to spermatozoa transport and protection. Notably, significant advancements have been made in dissecting seminal plasma components, revealing new insights into multiple aspects of sperm function, as well as fertilization and pregnancy outcomes in recent years. In this review, we summarize the state-of-art discoveries regarding SP compositions and their implications in male fertility, particularly describing the novel understanding of seminal plasma components and related modifications using “omics” approaches and mainly focusing on proteome and RNA-seq data in the latest decade. Meanwhile, we highlighted the proposed mechanism of the regulation of SP molecules on immunomodulation in the female reproductive tract. Moreover, we also discussed the proteins investigated as non-invasive diagnosis biomarkers for male infertility in the clinic.

A urine-based biomarker for chronic prostatitis/chronic pelvic pain syndrome: a retrospective multi-center study

Background

Chronic prostatitis (CP) or chronic pelvic pain syndrome (CPPS) is one of the most common diseases in young and middle-aged men, accounting for 30% of outpatient men in urology OPD. There are no definitive diagnostic criteria for CP or CPPS and no accepted therapies that cure the disease.

Methods

We identified 372 patients with CP diagnosed from 2015 to 2018 and collect the information of age, routine urinary test, express prostatic secretion (EPS), and NIH-Chronic Prostatitis Symptom Index (NIH-CPSI).

Results

Our study proved a correlation between the increase of prostatic exosomal proteins (PSEPs) level and NIH-CPSI scores. Spearman’s correlation coefficient showed a significant level correlation between NIH-CPSI and PSEP level (rs=0.194, P=0.0035). In the meantime, the correlation was found between the PSEP level and EPS-white blood cells. Spearman’s correlation coefficient showed that there was a significant hierarchical correlation between EPS-white blood cells and PSEP level (rs=0.183, P=0.001).

Conclusions

These findings highlight the potential of PSEP is a practical indicator of the symptomatic progression of CP/CPPS. Applications of PSEP assay may guide drug discovery and lead to better treatment to improve the patient’s quality of life.All in all, PSEP detection in urine is safe and effective, and it is worthy of further promotion and application in clinical practice.

Ratiometric Nanoparticle Array-Based Near-Infrared Fluorescent Probes for Quantitative Protein Sensing

Quantitative detection of protein biomarkers is crucial to medical diagnosis. Fluorescent probes have been frequently used for protein detection, but they suffered from various weaknesses such as lack of versatility. In particular, most of the reported probes were not capable of simultaneous qualitative and quantitative detection for various proteins. In this paper, we developed novel nanoparticle array-based near-infrared (NIR) ratiometric probes for potent protein analysis, in which the specific protein was able to be distinguished and quantitated within a group of 11 common proteins. The activity of β-galactosidases (β-gal) was temporarily inhibited by the adsorption to magnetic nanoparticles and restored to certain content by replacement with detected proteins, leading to distinctive readout of the enzyme-activatable NIR probe (DCM-β-gal). The readout of the sensor array against 11 proteins, as verified by isothermal titration calorimetry, was processed and transformed into canonical factors with the help of linear discrimination analysis. Moreover, the ratiometric signals of DCM-β-gal were translated to quantitatively detect proteins within the concentration range of 0-100 μg/mL. Based on clear differentiation within both two-dimensional and three-dimensional plots, different proteins could be detected with 100% accuracy with their concentration simultaneously determined, which endowed the sensing system with great potential in clinical diagnosis.

The extracellular SEMA domain attenuates intracellular apoptotic signaling of semaphorin 6A in lung cancer cells

Semaphorin 6A (SEMA6A), a membrane-bound protein, is downregulated in lung cancer tissue compared to its adjacent normal tissue. However, the functions of SEMA6A in lung cancer cells are still unclear. In the present study, full length SEMA6A and various truncations were transfected into lung cancer cells to investigate the role of the different domains of SEMA6A in cell proliferation and survival, apoptosis, and in vivo tumor growth. SEMA6A-induced cell signaling was explored using gene silencing, co-immunoprecipitation, and co-culture assays. Our results showed that overexpression of SEMA6A reduced the growth of lung cancer cells in vitro and in vivo, and silencing SEMA6A increased the proliferation of normal lung fibroblasts. Truncated SEMA6A lacking the SEMA domain or the extracellular region induced more apoptosis than full length SEMA6A, and reintroducing the SEMA domain attenuated the apoptosis. Fas-associated protein with death domain (FADD) bound to the cytosolic region of truncated SEMA6A and was involved in SEMA6A-associated cytosol-induced apoptosis. This study suggests a novel function of SEMA6A in inducing apoptosis via FADD binding in lung cancer cells.

Proteomic identification of turkey (Meleagris gallopavo) seminal plasma proteins

SDS-PAGE combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) and 2-dimensional electrophoresis (2DE) combined with matrix-assisted laser desorption/ionization time of flight/time of flight mass spectrometry (MALDI TOF/TOF) were applied to characterize the turkey seminal plasma proteome. LC-MS/MS led to the identification of 175 proteins, which were classified according to their function and to corresponding biochemical pathways. Using 2DE and MALDI TOF/TOF, 34 different turkey seminal plasma proteins could be identified, of which 20 were found in more than one spot, indicating different proteoforms of these proteins. For validation, antibodies against turkey albumin and ovoinhibitor as well as sperm acrosin were used in 2DE Western blots experiments. The bioinformatic analysis of the results indicates that turkey seminal plasma proteins may be involved in regulation of lipid metabolism [liver X receptor/retinoid X receptor (LXR/RXR) activation and farnesoid X receptor/retinoid X receptor (FXR/RXR) activation pathways)], endocytic entry of proteins and lipids at the plasma membrane (clathrin-mediated endocytosis pathway), and defense against pathogens (acute phase response signaling pathway) and energy production (glycolysis and gluconeogenesis). Moreover, a comparative meta-analysis of seminal plasma proteomes from other species indicated the presence of proteins specific for avian reproduction, but distinct differences between turkey and chicken seminal plasma proteomes were detected. The results of our study provide basic knowledge of the protein composition of turkey seminal plasma highlighting important physiological pathways which may play crucial roles in the sperm environment after ejaculation. This knowledge can be the basis to further develop procedures improving the reproduction of farmed turkeys.

The enigmatic seminal plasma: a proteomics insight from ejaculation to fertilization

BACKGROUND

The 'omics' approach for a noninvasive diagnosis of male reproductive system disorders has gained momentum during the last decade, particularly from a screening and prognosis point of view. Due to the rapid development in assisted reproductive technologies (ART) over the years, the major focus of proteomic studies has been around the ejaculated spermatozoa. Although seminal plasma is not a requirement for ART, the question arose whether the role of seminal plasma is merely to transport spermatozoa.

MAIN BODY

Seminal plasma (SP) contains a large diversity of proteins that are essential not only for sperm transport, but also for sperm protection and maturation. Most of the proteins bind to sperm surface through exosomes (epididymosomes and prostasomes), modulating sperm function, interaction with the female reproductive tract and finally fertilization. This review focuses on the state-of-art discoveries regarding SP proteome and its role in fertilization.

CONCLUSION

Tissue-specific proteins in the SP have emerged as fundamental contributors for protein biomarker discovery. This is important for a noninvasive diagnosis of male infertility and development of new therapeutic approaches. Moreover, ART success rates may be improved by taking into account the critical role of seminal proteome in fertilization.

Quantitative Mass Spectrometry-Based Proteomic Profiling for Precision Medicine in Prostate Cancer

Prostate cancer (PCa) is one of the most frequently diagnosed cancer among men in the western societies. Many PCa patients bear tumors that will not threat their lives if left untreated or if treatment is delayed. Our inability for early identification of these patients has resulted in massive overtreatment. Therefore, there is a great need of finding biomarkers for patient stratification according to prognostic risk; as well as there is a need for novel targets that can allow the development of effective treatments for patients that progress to castration-resistant PCa. Most biomarkers in cancer are proteins, including the widely-used prostate-specific antigen (PSA). Recent developments in mass spectrometry allow the identification and quantification of thousands of proteins and posttranslational modifications from small amounts of biological material, including formalin-fixed paraffin-embedded tissues, and biological fluids. Novel diagnostic and prognostic biomarkers have been identified in tissue, blood, urine, and seminal plasma of PCa patients, and new insights in the ethology and progression of this disease have been achieved using this technology. In this review, we summarize these findings and discuss the potential of this technology to pave the way toward the clinical implementation of precision medicine in PCa.

Serum quantitative proteomic analysis reveals potential zinc-associated biomarkers for nonbacterial prostatitis

BACKGROUND

Prostatitis is one of the most common urological problems afflicting adult men. The etiology and pathogenesis of nonbacterial prostatitis, which accounts for 90-95% of cases, is largely unknown. As serum proteins often indicate the overall pathologic status of patients, we hypothesized that protein biomarkers of prostatitis might be identified by comparing the serum proteomes of patients with and without nonbacterial prostatitis.

METHODS

All untreated samples were collected from subjects attending the Fangchenggang Area Male Health and Examination Survey (FAMHES). We profiled pooled serum samples from four carefully selected groups of patients (n = 10/group) representing the various categories of nonbacterial prostatitis (IIIa, IIIb, and IV) and matched healthy controls using a mass spectrometry-based 4-plex iTRAQ proteomic approach. More than 160 samples were validated by ELISA.

RESULTS

Overall, 69 proteins were identified. Among them, 42, 52, and 37 proteins were identified with differential expression in Category IIIa, IIIb, and IV prostatitis, respectively. The 19 common proteins were related to immunity and defense, ion binding, transport, and proteolysis. Two zinc-binding proteins, superoxide dismutase 3 (SOD3), and carbonic anhydrase I (CA1), were significantly higher in all types of prostatitis than in the control. A receiver operating characteristic curve estimated sensitivities of 50.4 and 68.1% and specificities of 92.1 and 83.8% for CA1 and SOD3, respectively, in detecting nonbacterial prostatitis. The serum CA1 concentration was inversely correlated to the zinc concentration in expressed-prostatic secretions.

CONCLUSIONS

Our findings suggest that SOD3 and CA1 are potential diagnostic markers of nonbacterial prostatitis, although further large-scale studies are required. The molecular profiles of nonbacterial prostatitis pathogenesis may lay a foundation for discovery of new therapies.

Comparative analysis of the seminal plasma proteomes of oligoasthenozoospermic and normozoospermic men

A comparative proteomic study of oligoasthenozoospermic and normozoospermic seminal plasmas was conducted to establish differences in protein expression. Oligoasthenozoospermia (when semen presents with a low concentration and reduced motility of spermatozoa) is common in male infertility. Two-dimensional protein maps from seminal plasma samples from 10 men with normozoospermia and 10 men with idiopathic oligoasthenozoospermia were obtained by isoelectric focusing followed by sodium dodecyl-sulphate polyacrylamide electrophoresis. Map images were analysed using dedicated software involving normalization, spot-to-spot volume comparison and statistical treatment of the results to establish the significance of differences between normal and oligoasthenozoospermic samples. Six out of 1028 spots showed over 1.5-fold relative intensity differences (P < 0.05, analysis of variance). Four proteins were identified by nano liquid chromatography-electrospray ionization-mass spectrometry/mass spectrometry of their tryptic peptides and database searches. Two proteins were more than three-fold under-expressed in oligoasthenozoospermia, namely epididymal secretory protein E1 and galectin-3-binding protein; the other (lipocalin-1 and a prolactin-inducible protein form) were over-expressed. The identity and differential expression of epididymal secretory protein E1 was verified by Western-blotting. The statistically significant differential expression of these four proteins in oligoasthenozoospermia compared with normozoospermia provides a molecular basis for further investigations into the pathogenic mechanisms underlying idiopathic oligoasthenozoospermia.

Exploring the human seminal plasma proteome: an unexplored gold mine of biomarker for male infertility and male reproduction disorder

BACKGROUND

The human seminal fluid is a complex body fluid. It is not known how many proteins are expressed in the seminal plasma; however in analog with the blood it is possible up to 10,000 proteins are expressed in the seminal plasma. The human seminal fluid is a rich source of potential biomarkers for male infertility and reproduction disorder.

METHODS

In this review, the ongoing list of proteins identified from the human seminal fluid was collected. To date, 4188 redundant proteins of the seminal fluid are identified using different proteomics technology, including 2-DE, SDS-PAGE-LC-MS/MS, MudPIT. However, this was reduced to a database of 2168 non-redundant protein using UniProtKB/Swiss-Prot reviewed database.

RESULTS

The core concept of proteome were analyzed including pI, MW, Amino Acids, Chromosome and PTM distribution in the human seminal plasma proteome. Additionally, the biological process, molecular function and KEGG pathway were investigated using DAVID software. Finally, the biomarker identified in different male reproductive system disorder was investigated using proteomics platforms so far.

CONCLUSION

In this study, an attempt was made to update the human seminal plasma proteome database. Our finding showed that human seminal plasma studies used to date seem to have converged on a set of proteins that are repeatedly identified in many studies and that represent only a small fraction of the entire human seminal plasma proteome.

Differential protein expression in seminal plasma from fertile and infertile males

AIM

The aim of this study was to analyze human seminal plasma proteins in association with male fertility status using the proteomic mass spectrometry technology Surface-Enhanced Laser Desorption Ionization Time-of-Flight (SELDI-TOF-MS).

MATERIALS AND METHODS

Semen analysis was performed using conventional methods. Protein profiles of the seminal plasma were obtained by SELDI-TOF mass spectrometry over a strong anion exchanger, ProteinChip(®) Q10 array.

RESULTS AND CONCLUSION

We found statistically significant differences in motility and sperm count between fertile and infertile men. In addition, we observed ten seminal proteins that are significantly up-regulated in the infertile group. In conclusion, comparison of seminal plasma proteome in fertile and infertile men provides new aspects in the physiology of male fertility and might help in identifying novel markers of male infertility.

Tandem mass spectral libraries of peptides in digests of individual proteins: Human Serum Albumin (HSA)

This work presents a method for creating a mass spectral library containing tandem spectra of identifiable peptide ions in the tryptic digestion of a single protein. Human serum albumin (HSA(1)) was selected for this purpose owing to its ubiquity, high level of characterization and availability of digest data. The underlying experimental data consisted of ∼3000 one-dimensional LC-ESI-MS/MS runs with ion-trap fragmentation. In order to generate a wide range of peptides, studies covered a broad set of instrument and digestion conditions using multiple sources of HSA and trypsin. Computer methods were developed to enable the reliable identification and reference spectrum extraction of all peptide ions identifiable by current sequence search methods. This process made use of both MS2 (tandem) spectra and MS1 (electrospray) data. Identified spectra were generated for 2918 different peptide ions, using a variety of manually-validated filters to ensure spectrum quality and identification reliability. The resulting library was composed of 10% conventional tryptic and 29% semitryptic peptide ions, along with 42% tryptic peptide ions with known or unknown modifications, which included both analytical artifacts and post-translational modifications (PTMs) present in the original HSA. The remaining 19% contained unexpected missed-cleavages or were under/over alkylated. The methods described can be extended to create equivalent spectral libraries for any target protein. Such libraries have a number of applications in addition to their known advantages of speed and sensitivity, including the ready re-identification of known PTMs, rejection of artifact spectra and a means of assessing sample and digestion quality.

Novel approaches for the identification of biomarkers of aggressive prostate cancer

The ability to distinguish indolent from aggressive prostate tumors remains one of the greatest challenges in the management of this disease. Ongoing efforts to establish a panel of molecular signatures, comprising gene expression profiles, proteins, epigenetic patterns, or a combination of these alterations, are being propelled by rapid advancements in 'omics' technologies. The identification of such biomarkers in biological fluids is an especially attractive goal for clinical applications. Here, we summarize recent progress in the identification of candidate prognostic biomarkers of prostate cancer using biological fluid samples.

Functional proteomic analysis of seminal plasma proteins in men with various semen parameters

BACKGROUND

Alterations at the molecular level in spermatozoa and seminal plasma can affect male fertility. The objective of this study was to determine if analysis of differential expression of proteins in varying semen parameters can serve as potential biomarkers for male infertility.

METHODS

The differential expression of proteins in the seminal plasma of men based on sperm count and morphology were examined utilizing proteomic tools. Subjects were categorized based on sperm concentration and morphology into 4 groups: 1) normal sperm count and normal morphology (NN); 2) normal sperm count and abnormal morphology (NA); 3) oligozoospermia and normal morphology (ON); and 4) oligozoospermia and abnormal morphology (OA). Proteomic analysis was performed by LC-MS/MS followed by functional bioinformatics analysis. Protein distribution in the NA, ON and OA groups was compared with that of the NN group.

RESULTS

Twenty proteins were differentially expressed among the 4 groups. Among the unique proteins identified, 3 were downregulated in the NA group, 1 in the ON group and 1 in the OA group while 2 were upregulated in the ON and OA groups. The functional analysis 1) identified biological regulation as the major processes affected and 2) determined that most of the identified proteins were of extracellular origin.

CONCLUSIONS

We have identified proteins that are over-or underexpressed in the seminal plasma of men with poor sperm quality. The distinct presence of some of the proteins may serve as potential biomarkers and provide insight into the mechanistic role played by these proteins in male infertility. Further studies using Western Blot analysis are required to validate these findings.