Core fucosylation and alpha2-3 sialylation in serum N-glycome is significantly increased in prostate cancer comparing to benign prostate hyperplasia

Multiplex Determination of Glycan Profiles on Urinary Prostate-Specific Antigen by Quartz-Crystal Microbalance Combined with Surface-Enhanced Raman Scattering

Prostate cancer remains a major health concern, with prostate-specific antigen (PSA) being a key biomarker for its detection and monitoring. However, PSA levels often fall into a "gray zone", where PSA levels are not clearly indicative of cancer, thus complicating early diagnosis and treatment decisions. Glycosylation profiles, which often differ between healthy and diseased cells, have emerged as potential biomarkers to enhance the specificity and sensitivity of cancer diagnosis in these ambiguous cases. We propose the integration of two complementary techniques, namely quartz-crystal microbalance with dissipation (QCM-D) and surface-enhanced Raman scattering (SERS) to study PSA glycan profiles. QCM-D offers real-time operation, PSA mass quantification, and label-free detection with high sensitivity, as well as enhanced specificity and reduced cross-reactivity when using nucleic acid aptamers as capture ligands. Complementary SERS sensing enables the determination of the glycosylation pattern on PSA, at low concentrations and without the drawbacks of photobleaching, thereby facilitating multiplexed glycosylation pattern analysis. This integrated setup could retrieve a data set comprising analyte concentrations and associated glycan profiles in relevant biological samples, which may eventually improve early disease detection and monitoring. Prostate-specific antigen (PSA), a glycoprotein secreted by prostate epithelial cells, serves as our proof-of-concept analyte. Our platform allows multiplex targeting of PSA multiplex glycosylation profiles of PSA at "gray zone" concentrations for prostate cancer diagnosis. We additionally show the use of SERS for glycan analysis in PSA secreted from prostate cancer cell lines after androgen-based treatment. Differences in PSA glycan profiles from resistant cell lines after androgen-based treatment may eventually improve cancer treatment.

Glycosylation: mechanisms, biological functions and clinical implications

Protein post-translational modification (PTM) is a covalent process that occurs in proteins during or after translation through the addition or removal of one or more functional groups, and has a profound effect on protein function. Glycosylation is one of the most common PTMs, in which polysaccharides are transferred to specific amino acid residues in proteins by glycosyltransferases. A growing body of evidence suggests that glycosylation is essential for the unfolding of various functional activities in organisms, such as playing a key role in the regulation of protein function, cell adhesion and immune escape. Aberrant glycosylation is also closely associated with the development of various diseases. Abnormal glycosylation patterns are closely linked to the emergence of various health conditions, including cancer, inflammation, autoimmune disorders, and several other diseases. However, the underlying composition and structure of the glycosylated residues have not been determined. It is imperative to fully understand the internal structure and differential expression of glycosylation, and to incorporate advanced detection technologies to keep the knowledge advancing. Investigations on the clinical applications of glycosylation focused on sensitive and promising biomarkers, development of more effective small molecule targeted drugs and emerging vaccines. These studies provide a new area for novel therapeutic strategies based on glycosylation.

Relevance of glyco-biomakers and glycan profiles in cancer stem cells

Altered and aberrant glycosylation signatures have been linked to being a hallmark in a variety of human disorders including cancer. Cancer stem cells (CSCs), capable of self-renewal and differentiation, have recently been credited with a unique notion of disease genesis and implicated as the cause for initiation and recurrence of the disease in a new regime of neoplastic transformations hypothesis. Many biomarkers relating to diagnostic and prognostic intents have been discovered using the ubiquitous and abundant surface glycan patterns on CSCs. Various technological advancements have been developed to identify and determine concerns with glycosylation structure. However, the nature and purpose of the glycan moiety on these glycosylation pattern have not yet been thoroughly investigated. This review, thus, summarizes the process of glycosylation in CSCs, variations in glycosylation patterns in various stem cells, aberrant glycosylation patterns in cancer, the role of glycosylation in tumor cell adhesion, cell-matrix interactions, and signaling, as well as cancer detection and treatment. The function of carbohydrates as prospective serum biomarkers, some clinically authorized biomarkers, and potential novel biomarkers relating to cancer disease diagnosis and prognosis are also discussed in the review.

Liquid Biomarkers in Prostate Cancer Diagnosis: Current Status and Emerging Prospects

Prostate cancer (PCa) is a major health concern that necessitates appropriate diagnostic approaches for timely intervention. This review critically evaluates the role of liquid biopsy techniques, focusing on blood- and urine-based biomarkers, in overcoming the limitations of conventional diagnostic methods. The 4Kscore test and Prostate Health Index have demonstrated efficacy in distinguishing PCa from benign conditions. Urinary biomarker tests such as PCa antigen 3, MyProstateScore, SelectMDx, and ExoDx Prostate IntelliScore test have revolutionized risk stratification and minimized unnecessary biopsies. Emerging biomarkers, including non-coding RNAs, circulating tumor DNA, and prostate-specific antigen (PSA) glycosylation, offer valuable insights into PCa biology, enabling personalized treatment strategies. Advancements in non-invasive liquid biomarkers for PCa diagnosis may facilitate the stratification of patients and avoid unnecessary biopsies, particularly when PSA is in the gray area of 4 to 10 ng/mL.

In-Depth Glycoproteomic Assay of Urinary Prostatic Acid Phosphatase

Prostate-specific antigen (PSA) is a well-known clinical biomarker in prostate cancer (PCa) diagnosis, but a better test is still needed, as the serum-level-based PSA quantification exhibits limited specificity and comes with poor predictive value. Prior to PSA, prostatic acid phosphatase (PAP) was used, but it was replaced by PSA because PSA improved the early detection of PCa. Upon revisiting PAP and its glycosylation specifically, it appears to be a promising new biomarker candidate. Namely, previous studies have indicated that PAP glycoforms differ between PCa and non-PCa individuals. However, an in-depth characterization of PAP glycosylation is still lacking. In this study, we established an in-depth glycoproteomic assay for urinary PAP by characterizing both the micro- and macroheterogeneity of the PAP glycoprofile. For this purpose, PAP samples were analyzed by capillary electrophoresis coupled to mass spectrometry after affinity purification from urine and proteolytic digestion. The developed urinary PAP assay was applied on a pooled DRE (digital rectal examination) urine sample from nine individuals. Three glycosylation sites were characterized, namely N94, N220, and N333, via N-glycopeptide analysis. Taking sialic acid linkage isomers into account, a total of 63, 27, and 4 N-glycan structures were identified, respectively. The presented PAP glycoproteomic assay will enable the determination of potential glycomic biomarkers for the early detection and prognosis of PCa in cohort studies.

Glycan-specific molecularly imprinted polymers towards cancer diagnostics: merits, applications, and future perspectives

Aberrant glycans are a hallmark of cancer states. Notably, emerging evidence has demonstrated that the diagnosis of cancers with tumour-specific glycan patterns holds great potential to address unmet medical needs, especially in improving diagnostic sensitivity and selectivity. However, despite vast glycans having been identified as potent markers, glycan-based diagnostic methods remain largely limited in clinical practice. There are several reasons that prevent them from reaching the market, and the lack of anti-glycan antibodies is one of the most challenging hurdles. With the increasing need for accelerating the translational process, numerous efforts have been made to find antibody alternatives, such as lectins, boronic acids and aptamers. However, issues concerning affinity, selectivity, stability and versatility are yet to be fully addressed. Molecularly imprinted polymers (MIPs), synthetic antibody mimics with tailored cavities for target molecules, hold the potential to revolutionize this dismal progress. MIPs can bind a wide range of glycan markers, even those without specific antibodies. This capacity effectively broadens the clinical applicability of glycan-based diagnostics. Additionally, glycoform-resolved diagnosis can also be achieved through customization of MIPs, allowing for more precise diagnostic applications. In this review, we intent to introduce the current status of glycans as potential biomarkers and critically evaluate the challenges that hinder the development of in vitro diagnostic assays, with a particular focus on glycan-specific recognition entities. Moreover, we highlight the key role of MIPs in this area and provide examples of their successful use. Finally, we conclude the review with the remaining challenges, future outlook, and emerging opportunities.

Identification of Core-Fucosylated Glycoproteins by Single-Step Truncation of N-Glycans

Alpha-1,6 core fucosylation (CF) is a unique glycoform of N-glycans, and studies showed that CF modifications are involved in the occurrence and progression of various diseases and may provide potential disease biomarkers. Current strategies for the CF glycoproteome are often based on multistep enrichment of glycoproteins or glycopeptides and sequential cleavage with different glycosidases to truncate the N-glycans. Although the detection ability of low-abundance glycoproteins is improved, sample loss, high cost, and the time-consuming multistep operation also affect the reproducibility of results and the practicality of the method. Here we developed a single-step truncation (SST) strategy and evaluated its potential for the CF glycoproteome of human serum. The SST strategy has the advantages of fewer operational steps, lower cost, higher number of identifications, and better quantitative stability compared with previous approaches and provides an efficient solution for large-scale quantitative analysis of the CF glycoproteome. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Single-step truncation strategy for core fucosylation glycoproteome analysis in human serum Basic Protocol 2: Liquid chromatography-tandem mass spectrometry quantification of site-specific core fucosylation glycopeptides Alternate Protocol: Pretreatment of cellular samples of core fucosylation glycoproteome with single-step truncation strategy.

Targeting aberrant sialylation and fucosylation in prostate cancer cells using potent metabolic inhibitors

Aberrant glycosylation is a hallmark of cancer and is not just a consequence, but also a driver of a malignant phenotype. In prostate cancer, changes in fucosylated and sialylated glycans are common and this has important implications for tumor progression, metastasis, and immune evasion. Glycans hold huge translational potential and new therapies targeting tumor-associated glycans are currently being tested in clinical trials for several tumor types. Inhibitors targeting fucosylation and sialylation have been developed and show promise for cancer treatment, but translational development is hampered by safety issues related to systemic adverse effects. Recently, potent metabolic inhibitors of sialylation and fucosylation were designed that reach higher effective concentrations within the cell, thereby rendering them useful tools to study sialylation and fucosylation as potential candidates for therapeutic testing. Here, we investigated the effects of global metabolic inhibitors of fucosylation and sialylation in the context of prostate cancer progression. We find that these inhibitors effectively shut down the synthesis of sialylated and fucosylated glycans to remodel the prostate cancer glycome with only minor apparent side effects on other glycan types. Our results demonstrate that treatment with inhibitors targeting fucosylation or sialylation decreases prostate cancer cell growth and downregulates the expression of genes and proteins important in the trajectory of disease progression. We anticipate our findings will lead to the broader use of metabolic inhibitors to explore the role of fucosylated and sialylated glycans in prostate tumor pathology and may pave the way for the development of new therapies for prostate cancer.

Age-Related Changes in Serum N-Glycome in Men and Women-Clusters Associated with Comorbidity

(1) Aim: To describe, in a general adult population, the serum N-glycome in relation to age in men and women, and investigate the association of N-glycome patterns with age-related comorbidity; (2) Methods: The serum N-glycome was studied by hydrophilic interaction chromatography with ultra-performance liquid chromatography in 1516 randomly selected adults (55.3% women; age range 18-91 years). Covariates included lifestyle factors, metabolic disorders, inflammatory markers, and an index of comorbidity. Principal component analysis was used to define clusters of individuals based on the 46 glycan peaks obtained in chromatograms; (3) Results: The serum N-glycome changed with ageing, with significant differences between men and women, both in individual N-glycan peaks and in groups defined by common features (branching, galactosylation, sialylation, fucosylation, and oligomannose). Through K-means clustering algorithm, the individuals were grouped into a cluster characterized by abundance of simpler N-glycans and a cluster characterized by abundance of higher-order N-glycans. The individuals of the first cluster were older, showed higher concentrations of glucose and glycation markers, higher levels of some inflammatory markers, lower glomerular filtration rate, and greater comorbidity index; (4) Conclusions: The serum N-glycome changes with ageing with sex dimorphism. The N-glycome could be, in line with the inflammaging hypothesis, a marker of unhealthy aging.

Differential analysis of core-fucosylated glycoproteomics enabled by single-step truncation of N-glycans

Alpha-1,6 fucosylation of N-glycans (core fucosylation, CF) represents a unique form of N-glycans and is widely involved in disease progression. In order to accurately identify CF glycoproteins, several approaches have been developed based on sequential cleavage with different glycosidases to truncate the N-glycans. Since multi-step sample treatments may introduce quantitation bias and affect the practicality of these approaches in large-scale applications. Here, we systematically evaluated the performance of the single-step treatment of intact glycopeptides by endoglycosidase F3 for CF glycoproteome. The single-step truncation (SST) strategy demonstrated higher quantitative stability and higher efficiency compared with previous approaches. The strategy was further practiced on both cell lines and serum samples. The dysregulation of CF glycopeptides between preoperative and postoperative serum from patients with pancreatic ductal adenocarcinoma was revealed, and the CF modifications of BCHE_N369, CDH5_N112 and SERPIND1_N49 were found to be potential prognostic markers. This study thus provides an efficient solution for large-scale quantitative analysis of the CF glycoproteome.

Capitalizing glycomic changes for improved biomarker-based cancer diagnostics

Cancer serum biomarkers are valuable or even indispensable for cancer diagnostics and/or monitoring and, currently, many cancer serum markers are routinely used in the clinic. Most of those markers are glycoproteins, carrying cancer-specific glycan structures that can provide extra-information for cancer monitoring. Nonetheless, in the majority of cases, this differential feature is not exploited and the corresponding analytical assays detect only the protein amount, disregarding the analysis of the aberrant glycoform. Two exceptions to this trend are the biomarkers α-fetoprotein (AFP) and cancer antigen 19-9 (CA19-9), which are clinically monitored for their cancer-related glycan changes, and only the AFP assay includes quantification of both the protein amount and the altered glycoform. This narrative review demonstrates, through several examples, the advantages of the combined quantification of protein cancer biomarkers and the respective glycoform analysis, which enable to yield the maximum information and overcome the weaknesses of each individual analysis. This strategy allows to achieve higher sensitivity and specificity in the detection of cancer, enhancing the diagnostic power of biomarker-based cancer detection tests.

Analysis of Protein Glycosylation after Rapid Digestion Using Protease-Containing Membranes in Spin Columns

Glycosylation is an important protein post-translational modification that plays a pivotal role in the bioactivity of therapeutic proteins and in the infectivity of viral proteins. Liquid chromatography with tandem mass spectrometry readily identifies protein glycans with site specificity. However, the overnight incubation used in conventional in-solution proteolysis leads to high turnaround times for glycosylation analysis, particularly when sequential in-solution digestions are needed for site-specific glycan identification. Using bovine fetuin as a model glycoprotein, this work first shows that in-membrane digestion in ∼3 min yields similar glycan identification and quantitation when compared to overnight in-solution digestion. Protease-containing membranes in a spin column enable digestion of therapeutic proteins (trastuzumab and erythropoietin) and a viral protein (SARS-CoV-2 receptor binding domain) in ∼30 s. Glycan identification is similar after in-solution and in-membrane digestion, and limited in-membrane digestion enhances the identification of high-mannose glycans in trastuzumab. Finally, stacked membranes containing trypsin and chymotrypsin allow fast sequential proteolytic digestion to site-specifically identify the glycans of SARS-CoV-2 receptor binding domain. One can easily assemble the protease-containing membranes in commercial spin columns, and spinning multiple columns simultaneously will facilitate parallel analyses.

Beyond glyco-proteomics-Understanding the role of genetics in cancer biomarkers

The development of robust cancer biomarkers is the most effective way to improve overall survival, as early detection and treatment leads to significantly better clinical outcomes. Many of the cancer biomarkers that have been identified and are clinically utilized are glycoproteins, oftentimes a specific glycoform. Aberrant glycosylation is a common theme in cancer, with dysregulated glycosylation driving tumor initiation and metastasis, and abnormal glycosylation can be detection both on the tissue surface and in serum. However, most cancer types are heterogeneous in regard to tumor genomics, and this heterogeneity extends to cancer glycomics. This limits the sensitivity of standalone glycan-based biomarkers, which has slowed their implementation clinically. However, if targeted biomarker development can take into account genomic tumor information, the development of complementary biomarkers that target unique cancer subgroups can be accomplished. This idea suggests the need for algorithm-based cancer biomarkers, which can utilize multiple biomarkers along with relevant demographic information. This concept has already been established in the detection of hepatocellular carcinoma with the GALAD score, and an algorithm-based approach would likely be effective in improving biomarker sensitivity for additional cancer types. In order to increase cancer diagnostic biomarker sensitivity, there must be more targeted biomarker development that considers tumor genomic, proteomic, metabolomic, and clinical data while identifying tumor biomarkers.

High-Throughput Glycomic Methods

Glycomics aims to identify the structure and function of the glycome, the complete set of oligosaccharides (glycans), produced in a given cell or organism, as well as to identify genes and other factors that govern glycosylation. This challenging endeavor requires highly robust, sensitive, and potentially automatable analytical technologies for the analysis of hundreds or thousands of glycomes in a timely manner (termed high-throughput glycomics). This review provides a historic overview as well as highlights recent developments and challenges of glycomic profiling by the most prominent high-throughput glycomic approaches, with N-glycosylation analysis as the focal point. It describes the current state-of-the-art regarding levels of characterization and most widely used technologies, selected applications of high-throughput glycomics in deciphering glycosylation process in healthy and disease states, as well as future perspectives.

Characterization of core fucosylation via sequential enzymatic treatments of intact glycopeptides and mass spectrometry analysis

Core fucosylation of N-linked glycoproteins has been linked to the functions of glycoproteins in physiological and pathological processes. However, quantitative characterization of core fucosylation remains challenging due to the complexity and heterogeneity of N-linked glycosylation. Here we report a mass spectrometry-based method that employs sequential treatment of intact glycopeptides with enzymes (STAGE) to analyze site-specific core fucosylation of glycoproteins. The STAGE method utilizes Endo F3 followed by PNGase F treatment to generate mass signatures for glycosites that are formerly modified by core fucosylated N-linked glycans. We benchmark the STAGE method and use it to characterize site specific core fucosylation of glycoproteins from human hepatocellular carcinoma and pancreatic ductal adenocarcinoma, resulting in the identification of 1130 and 782 core fucosylated glycosites, respectively. These results indicate that our STAGE method enables quantitative characterization of core fucosylation events from complex protein mixtures, which may benefit our understanding of core fucosylation functions in various diseases.

Aberrant Fucosylation of Saliva Glycoprotein Defining Lung Adenocarcinomas Malignancy

Aberrant glycosylation is a hallmark of cancer found during tumorigenesis and tumor progression. Lung cancer (LC) induced by oncogene mutations has been detected in the patient's saliva, and saliva glycosylation has been altered. Saliva contains highly glycosylated glycoproteins, the characteristics of which may be related to various diseases. Therefore, elucidating cancer-specific glycosylation in the saliva of healthy, non-cancer, and cancer patients can reveal whether tumor glycosylation has unique characteristics for early diagnosis. In this work, we used a solid-phase chemoenzymatic method to study the glycosylation of saliva glycoproteins in clinical specimens. The results showed that the α1,6-core fucosylation of glycoproteins was increased in cancer patients, whereas α1,2 or α1,3 fucosylation was significantly increased. We further analyzed the expression of fucosyltransferases responsible for α1,2, α1,3, and α1,6 fucosylation. The fucosylation of the saliva of cancer patients is drastically different from that of non-cancer or health controls. These results indicate that the glycoform of saliva fucosylation distinguishes LC from other diseases, and this feature has the potential to diagnose lung adenocarcinoma.

Hyperglycemia alters N-glycans on colon cancer cells through increased production of activated monosaccharides

Diabetes Mellitus (DM) is both, correlated and a known risk factor for colorectal cancer (CRC). Besides favoring the incidence of CRC, DM also accelerates its progression, worsening its prognosis. Previously, hyperglycemia, the DM hallmark, has been shown to lead to aberrant glycosylation of CRC cells, heightening their malignancy both in vivo and in vitro. Here we use mass spectrometry to elucidate the composition and putative structures of N-glycans expressed by MC38 cultured in normoglycemic (LG) and hyperglycemic-like conditions (HG). N-glycans, 67, were identified in MC38 cells cultured in LG and HG. The cells grown in HG showed a greater abundance of N-glycans when compared to LNG cells, without changes in the proportion of sialylated, fucosylated and mannosylated N-glycans. Among the identified N-glycans, 16 were differentially expressed, mostly mannosylated and fucosylated, with a minority of them being sialylated. Metabolomics analysis indicates that the alterations observed in the N-glycosylation may be mostly due to increase of the activated monosaccharides pool, through an increased glucose entrance into the cells. The alterations found here corroborate data from the literature regarding the progression of CRC, advocating for development or repositioning of effective treatments against CRC in diabetic patients.

Changes in Serum N-Glycome for Risk Drinkers: A Comparison with Standard Markers for Alcohol Abuse in Men and Women

Background and aim: Glycomic alterations serve as biomarker tools for different diseases. The present study aims to evaluate the diagnostic capability of serum N-glycosylation to identify alcohol risk drinking in comparison with standard markers. Methods: We included 1516 adult individuals (age range 18–91 years; 55.3% women), randomly selected from a general population. A total of 143 (21.0%) men and 50 (5.9%) women were classified as risk drinkers after quantification of daily alcohol consumption and the Alcohol Use Disorders Identification Test (AUDIT). Hydrophilic interaction ultra-performance liquid chromatography (HILIC-UPLC) was used for the quantification of 46 serum N-glycan peaks. Serum gamma-glutamyltransferase (GGT), carbohydrate-deficient transferrin (CDT), and red blood cell mean corpuscular volume (MCV) were measured by standard clinical laboratory methods. Results: Variations in serum N-glycome associated risk drinking were more prominent in men compared to women. A unique combination of N-glycan peaks selected by the selbal algorithm shows good discrimination between risk-drinkers and non-risk drinkers for men and women. Receiver operating characteristics (ROC) curves show accuracy for the diagnosis of risk drinking, which is comparable to that of the golden standards, GGT, MCV and CDT markers for men and women. Additionally, the inclusion of N-glycan peaks improves the diagnostic accuracy of the standard markers, although it remains relatively low, due to low sensitivity. For men, the area under the ROC curve using N-glycome data is 0.75, 0.76, and 0.77 when combined with GGT, MCV, and CDT, respectively. In women, the areas were 0.76, 0.73, and 0.73, respectively. Conclusion: Risk drinking is associated with significant variations in the serum N-glycome, which highlights its potential diagnostic utility.

Glycosylation Changes in Prostate Cancer Progression

Prostate Cancer (PCa) is the most commonly diagnosed malignancy and second leading cause of cancer-related mortality in men. With the use of next generation sequencing and proteomic platforms, new biomarkers are constantly being developed to both improve diagnostic sensitivity and specificity and help stratify patients into different risk groups for optimal management. In recent years, it has become well accepted that altered glycosylation is a hallmark of cancer progression and that the glycan structures resulting from these mechanisms show tremendous promise as both diagnostic and prognostic biomarkers. In PCa, a wide range of structural alterations to glycans have been reported such as variations in sialylation and fucosylation, changes in branching, altered levels of Lewis and sialyl Lewis antigens, as well as the emergence of high mannose "cryptic" structures, which may be immunogenic and therapeutically relevant. Furthermore, aberrant expression of galectins, glycolipids, and proteoglycans have also been reported and associated with PCa cell survival and metastasis. In this review, we discuss the findings from various studies that have explored altered N- and O-linked glycosylation in PCa tissue and body fluids. We further discuss changes in O-GlcNAcylation as well as altered expression of galectins and glycoconjugates and their effects on PCa progression. Finally, we emphasize the clinical utility and potential impact of exploiting glycans as both biomarkers and therapeutic targets to improve our ability to diagnose clinically relevant tumors as well as expand treatment options for patients with advanced disease.

Fucosylation in Urological Cancers

Fucosylation is an oligosaccharide modification that plays an important role in immune response and malignancy, and specific fucosyltransferases (FUTs) catalyze the three types of fucosylations: core-type, Lewis type, and H type. FUTs regulate cancer proliferation, invasiveness, and resistance to chemotherapy by modifying the glycosylation of signaling receptors. Oligosaccharides on PD-1/PD-L1 proteins are specifically fucosylated, leading to functional modifications. Expression of FUTs is upregulated in renal cell carcinoma, bladder cancer, and prostate cancer. Aberrant fucosylation in prostate-specific antigen (PSA) could be used as a novel biomarker for prostate cancer. Furthermore, elucidation of the biological function of fucosylation could result in the development of novel therapeutic targets. Further studies are needed in the field of fucosylation glycobiology in urological malignancies.

Simultaneous analysis of serum α2,3-linked sialylation and core-type fucosylation of prostate-specific antigen for the detection of high-grade prostate cancer

BACKGROUND

Altered prostate-specific antigen (PSA) glycosylation patterns can be useful biomarkers in detecting high-grade prostate cancer (HGPC). The microfluidic immunoassay system can analyse α2,3-linked sialylated PSA (α2,3-Sia-PSA) and α1,6-linked fucosylated PSA (α1,6-Fuc-PSA) using different lectins, Mackkia amurensis agglutinin and Pholiota squarrosa lectin, respectively. Here, we investigated the diagnostic value of simultaneous analysis of α2,3-Sia-PSA and α1,6-Fuc-PSA for the detection of HGPC.

METHODS

Men with serum PSA levels of 4-20 ng/mL who underwent prostate biopsy were included. The model to predict HGPC (Gleason grade ≥2) was constructed by multivariate logistic regression analysis, in combination with α2,3-Sia-PSA and α1,6-Fuc-PSA (SF index).

RESULTS

In the development cohort (n = 150), the SF index showed good discrimination for HGPC (area under the receiver-operating curve (AUC) 0.842; 95% confidence interval (CI) 0.782-0.903), compared to the single PSA test (AUC 0.632, 95% CI 0.543-0.721), α2,3-Sia-PSA (AUC 0.711, 95% CI 0.629-0.793) and α1,6-Fuc-PSA (AUC 0.738, 95% CI 0.657-0.819). Decision-curve analysis showed the superior benefit of the SF index. In the validation cohort (n = 57), the SF index showed good discrimination for HGPC (AUC 0.769, 95% CI 0.643-0.895).

CONCLUSIONS

The SF index could differentiate HGPC, providing useful information for decision making for prostate biopsy in men with abnormal PSA levels.

Lectins applied to diagnosis and treatment of prostate cancer and benign hyperplasia: A review

Environmental factors, as well as genetic factors, contribute to the increase in prostate cancer cases (PCa), the second leading cause of cancer death in men. This fact calls for the development of more reliable, quick and low-cost early detection tests to distinguish between malignant and benign cases. Abnormal cell glycosylation pattern is a promising PCa marker for this purpose. Proteins, such as lectins can decode the information contained in the glycosylation patterns. Several studies have reported on applications of plant lectins as diagnostic tools for PCa considering the ability to differentiate it from benign cases. In addition, they can be used to detect, separate and differentiate the glycosylation patterns of cells or proteins present in serum, urine and semen. Herein, we present an overview of these studies, showing the lectins that map glycans differentially expressed in PCa, as well as benign hyperplasia (BPH). We further review their applications in biosensors, histochemical tests, immunoassays, chromatography, arrays and, finally, their therapeutic potential. This is the first study to review vegetable lectins applied specifically to PCa.

Integrated workflow for urinary prostate specific antigen N-glycosylation analysis using sdAb partitioning and downstream capillary electrophoresis separation

Prostate cancer represents the second highest malignancy rate in men in all cancer diagnoses worldwide. The development and progression of prostate cancer is not completely understood yet at molecular level, but it has been reported that changes in the N-glycosylation of prostate-specific antigen (PSA) occur during tumor genesis. In this paper we report on the development and implementation of a high-throughput capillary electrophoresis based glycan analysis workflow for urinary PSA analysis. The technology utilizes selective, high yield single domain antibody based PSA capture, followed by preconcentration and capillary electrophoresis coupled with laser-induced fluorescence detection, resulting in high resolution N-glycan profiles. Urinary PSA glycan profiles were compared to a commercially available PSA standard revealing differences in their α2,3- and α2,6-sialylated isomers, proving the excellent selectivity of the suggested workflow. This is important as sialylation classification plays an important role in the differentiation between indolent, significant and aggressive forms of prostate cancer.

Immunoaffinity Capillary Electrophoresis in the Era of Proteoforms, Liquid Biopsy and Preventive Medicine: A Potential Impact in the Diagnosis and Monitoring of Disease Progression

Over the years, multiple biomarkers have been used to aid in disease screening, diagnosis, prognosis, and response to therapy. As of late, protein biomarkers are gaining strength in their role for early disease diagnosis and prognosis in part due to the advancements in identification and characterization of a distinct functional pool of proteins known as proteoforms. Proteoforms are defined as all of the different molecular forms of a protein derived from a single gene caused by genetic variations, alternative spliced RNA transcripts and post-translational modifications. Monitoring the structural changes of each proteoform of a particular protein is essential to elucidate the complex molecular mechanisms that guide the course of disease. Clinical proteomics therefore holds the potential to offer further insight into disease pathology, progression, and prevention. Nevertheless, more technologically advanced diagnostic methods are needed to improve the reliability and clinical applicability of proteomics in preventive medicine. In this manuscript, we review the use of immunoaffinity capillary electrophoresis (IACE) as an emerging powerful diagnostic tool to isolate, separate, detect and characterize proteoform biomarkers obtained from liquid biopsy. IACE is an affinity capture-separation technology capable of isolating, concentrating and analyzing a wide range of biomarkers present in biological fluids. Isolation and concentration of target analytes is accomplished through binding to one or more biorecognition affinity ligands immobilized to a solid support, while separation and analysis are achieved by high-resolution capillary electrophoresis (CE) coupled to one or more detectors. IACE has the potential to generate rapid results with significant accuracy, leading to reliability and reproducibility in diagnosing and monitoring disease. Additionally, IACE has the capability of monitoring the efficacy of therapeutic agents by quantifying companion and complementary protein biomarkers. With advancements in telemedicine and artificial intelligence, the implementation of proteoform biomarker detection and analysis may significantly improve our capacity to identify medical conditions early and intervene in ways that improve health outcomes for individuals and populations.

Associations Between Genetically Predicted Plasma N-Glycans and Prostate Cancer Risk: Analysis of Over 140,000 European Descendants

Background

Previous studies suggest a potential link between glycosylation and prostate cancer. To better characterize the relationship between the two, we performed a study to comprehensively evaluate the associations between genetically predicted blood plasma N-glycan levels and prostate cancer risk.

Methods

Using genetic variants associated with N-glycan levels as instruments, we evaluated the associations between levels of 138 plasma N-glycans and prostate cancer risk. We analyzed data of 79,194 cases and 61,112 controls of European ancestry included in the consortia of BPC3, CAPS, CRUK, PEGASUS, and PRACTICAL.

Results

We identified three N-glycans with genetically predicted levels in plasma to be associated with prostate cancer risk after Bonferroni correction. The estimated odds ratios (95% confidence intervals) were 1.29 (1.20–1.40), 0.80 (0.74–0.88), and 0.79 (0.72–0.87) for PGP18, PGP33, and PGP109, respectively, per every one standard deviation increase in genetically predicted levels of N-glycan. However, the instruments for these N-glycans only involved one to two variants. The proportions of variations that can be explained by the instruments range from 1.58% to 2.95% for these three N-glycans.

Conclusion

We observed associations between genetically predicted levels of three N-glycans PGP18, PGP33, and PGP109 and prostate cancer risk. Given the correlated nature of the N-glycans and that many N-glycans share genetic loci, pleiotropy is a major concern. Future work is warranted to better characterize the relationship between N-glycans and prostate cancer.

Glycosylation: Rising Potential for Prostate Cancer Evaluation

Simple Summary

Aberrant protein glycosylation is a well-known hallmark of cancer and is associated with differential expression of enzymes such as glycosyltransferases and glycosidases. The altered expression of the enzymes triggers cancer cells to produce glycoproteins with specific cancer-related aberrations in glycan structures. Increasing number of data indicate that glycosylation patterns of PSA and other prostate-originated proteins exert a potential to distinguish between benign prostate disease and cancer as well as among different stages of prostate cancer development and aggressiveness. This review summarizes the alterations in glycan sialylation, fucosylation, truncated O-glycans, and LacdiNAc groups outlining their potential applications in non-invasive diagnostic procedures of prostate diseases. Further research is desired to develop more general algorithms exploiting glycobiology data for the improvement of prostate diseases evaluation.

Abstract

Prostate cancer is the second most commonly diagnosed cancer among men. Alterations in protein glycosylation are confirmed to be a reliable hallmark of cancer. Prostate-specific antigen is the biomarker that is used most frequently for prostate cancer detection, although its lack of sensitivity and specificity results in many unnecessary biopsies. A wide range of glycosylation alterations in prostate cancer cells, including increased sialylation and fucosylation, can modify protein function and play a crucial role in many important biological processes in cancer, including cell signalling, adhesion, migration, and cellular metabolism. In this review, we summarize studies evaluating the prostate cancer associated glycosylation related alterations in sialylation, mainly α2,3-sialylation, core fucosylation, branched N-glycans, LacdiNAc group and presence of truncated O-glycans (sTn, sT antigen). Finally, we discuss the great potential to make use of glycans as diagnostic and prognostic biomarkers for prostate cancer.

Fucosyltransferase 8 regulation and breast cancer suppression by transcription factor activator protein 2γ

Alterations of glycosyltransferase expression are often associated with tumor occurrence and progression. Among the many glycosyltransferases, increased expression of fucosyltransferase 8 (FUT8) has been frequently observed to be involved in progression and metastasis of various types of cancer. The regulatory mechanisms of FUT8 expression remain unclear. FUT8 expression was shown, in this study, to be elevated in breast cancer. Systematic analysis revealed that transcription factor activator protein 2γ (AP-2γ) is the target gene of microRNA-10b (miR-10b), which we previously identified as a positive regulator of FUT8. Overexpression of AP-2γ inhibited FUT8 expression, with associated reduction of cell invasiveness and migration ability. AP-2γ was capable of binding to transcription factor STAT3, and phosphorylation of STAT3 induced transcription of the FUT8 gene. On the basis of our findings, we propose that binding of AP-2γ to STAT3 results in formation of the AP-2γ/STAT3 complex and consequent inhibition of STAT3 phosphorylation, thereby preventing entry of p-STAT3 into the nucleus to initiate FUT8 transcription. This study clarifies the molecular mechanisms whereby transcription factor AP-2γ regulates FUT8 expression in breast cancer.

Identification of Fucosylated SERPINA1 as a Novel Plasma Marker for Pancreatic Cancer Using Lectin Affinity Capture Coupled with iTRAQ-Based Quantitative Glycoproteomics

Pancreatic cancer (PC) is an aggressive cancer with a high mortality rate, necessitating the development of effective diagnostic, prognostic and predictive biomarkers for disease management. Aberrantly fucosylated proteins in PC are considered a valuable resource of clinically useful biomarkers. The main objective of the present study was to identify novel plasma glycobiomarkers of PC using the iTRAQ quantitative proteomics approach coupled with Aleuria aurantia lectin (AAL)-based glycopeptide enrichment and isotope-coded glycosylation site-specific tagging, with a view to analyzing the glycoproteome profiles of plasma samples from patients with non-metastatic and metastatic PC and gallstones (GS). As a result, 22 glycopeptides with significantly elevated levels in plasma samples of PC were identified. Fucosylated SERPINA1 (fuco-SERPINA1) was selected for further validation in 121 plasma samples (50 GS and 71 PC) using an AAL-based reverse lectin ELISA technique developed in-house. Our analyses revealed significantly higher plasma levels of fuco-SERPINA1 in PC than GS subjects (310.7 ng/mL v.s. 153.6 ng/mL, p = 0.0114). Elevated fuco-SERPINA1 levels were associated with higher TNM stage (p = 0.024) and poorer prognosis for overall survival (log-rank test, p = 0.0083). The increased plasma fuco-SERPINA1 levels support the utility of this protein as a novel prognosticator for PC.

FUT8 and Protein Core Fucosylation in Tumours: From Diagnosis to Treatment

Glycosylation changes are key molecular events in tumorigenesis, progression and glycosyltransferases play a vital role in the this process. FUT8 belongs to the fucosyltransferase family and is the key enzyme involved in N-glycan core fucosylation. FUT8 and/or core fucosylated proteins are frequently upregulated in liver, lung, colorectal, pancreas, prostate,breast, oral cavity, oesophagus, and thyroid tumours, diffuse large B-cell lymphoma, ependymoma, medulloblastoma and glioblastoma multiforme and downregulated in gastric cancer. They can be used as markers of cancer diagnosis, occurrence, progression and prognosis. Core fucosylated EGFR, TGFBR, E-cadherin, PD1/PD-L1 and α3β1 integrin are potential targets for tumour therapy. In addition, IGg1 antibody defucosylation can improve antibody affinity, which is another aspect of FUT8 that could be applied to tumour therapy.

A panel of selected serum protein biomarkers for the detection of aggressive prostate cancer

Background: Current PSA-based tests used to detect prostate cancer (PCa) lack sufficient specificity, leading to significant overdetection and overtreatment. Our previous studies showed that serum fucosylated PSA (Fuc-PSA) and soluble TEK receptor tyrosine kinase (Tie-2) had the ability to predict aggressive (AG) PCa. Additional biomarkers are needed to address this significant clinical problem. Methods: A comprehensive Pubmed search followed by multiplex immunoassays identified candidate biomarkers associated with AG PCa. Subsequently, multiplex and lectin-based immunoassays were applied to a case-control set of sera from subjects with AG PCa, low risk PCa, and non-PCa (biopsy negative). These candidate biomarkers were further evaluated for their ability as panels to complement the prostate health index (phi) in detecting AG PCa. Results: When combined through logistic regression, two panel of biomarkers achieved the best performance: 1) phi, Fuc-PSA, SDC1, and GDF-15 for the detection of AG from low risk PCa and 2) phi, Fuc-PSA, SDC1, and Tie-2 for the detection of AG from low risk PCa and non-PCa, with noticeable improvements in ROC analysis over phi alone (AUCs: 0.942 vs 0.872, and 0.934 vs 0.898, respectively). At a fixed sensitivity of 95%, the panels improved specificity with statistical significance in detecting AG from low risk PCa (76.0% vs 56%, p=0.029), and from low risk PCa and non-PCa (78.2% vs 65.5%, p=0.010). Conclusions: Multivariate panels of serum biomarkers identified in this study demonstrated clinically meaningful improvement over the performance of phi, and warrant further clinical validation, which may contribute to the management of PCa.

Narrative review of urinary glycan biomarkers in prostate cancer

Prostate cancer (PC) is the second most common cancer in men worldwide. The application of the prostate-specific antigen (PSA) test has improved the diagnosis and treatment of PC. However, the PSA test has become associated with overdiagnosis and overtreatment. Therefore, there is an unmet need for novel diagnostic, prognostic, and predictive biomarkers of PC. Urinary glycoproteins and exosomes are a potential source of PC glycan biomarkers. Urinary glycan profiling can provide noninvasive monitoring of tumor heterogeneity and aggressiveness throughout a treatment course. However, urinary glycan profiling is not popular due to technical disadvantages, such as complicated structural analysis that requires specialized expertise. The technological development of glycan analysis is a rapidly advancing field. A lectin-based microarray can detect aberrant glycoproteins in urine, including PSA glycoforms and exosomes. Glycan enrichment beads can enrich the concentration of N-linked glycans specifically. Capillary electrophoresis, liquid chromatography-tandem mass spectrometry, and matrix-assisted laser desorption/ionization-time of flight mass spectrometry can detect glycans directory. Many studies suggest potential of urinary glycoproteins, exosomes, and glycosyltransferases as a biomarker of PC. Although further technological challenges remain, urinary glycan analysis is one of the promising approaches for cancer biomarker discovery.

Tissue N-linked glycosylation as potential prognostic biomarker for biochemical recurrence-free survival

PURPOSE

Only few biomarkers have been evaluated for their prognostic value following radical prostatectomy. We explored if tissue N-glycosylation shows prognostic properties for biochemical recurrence (BCR)-free survival.

MATERIALS AND METHODS

Tissue N-glycosylation profile was determined from 82 prostate cancer (PCa) patients and prognostic features were compared to clinical and biochemical parameters for BCR-free survival.

RESULTS

Majority presented with Gleason score 3 + 4 (41%), extensive local disease (62%) and without pelvic lymph nodes invasion (83%). Several parameters (low T stage, low Gleason score, low EAU risk groups for BCR, absence of positive surgical margins, high ratio of fucosylated triantennary structures on total of multiantennary structures [3AFc/MA], low ratio of fucosylated biantennary with core-branched N-acetylglucosamine on total of biantennary structures, and high ratio of triantennary structures on total of multiantennary structures) proved to have a univariate beneficial effect on BCR-free survival. Multivariate analysis proved positive surgical margins and 3AFc/MA to be independent prognosticators.

CONCLUSIONS

Tissue N-glycans are a powerful prognostic tool and can be an asset in PCa as the ratio of 3AFc/MA is independently associated with BCR-free survival. This could be of clinical use in guiding patients following radical prostatectomy, e.g. referral to adjuvant radiotherapy. Further elaboration of this biomarker is warranted.

Uromodulin Isolation and Its N-Glycosylation Analysis by NanoLC-MS/MS

The glycoprotein uromodulin (UMOD) is the most abundant protein in urine, and N-glycans are critical for many biological functions of UMOD. Comprehensive glycan profiling of UMOD provides valuable information to understand the exact mechanisms of glycan-regulated functions. To perform comprehensive glycosylation analysis of UMOD from urine samples with limited volumes, we developed a streamlined workflow that included UMOD isolation from 5 mL of urine from 6 healthy adult donors (3 males and 3 females) and a glycosylation analysis using a highly sensitive and reproducible nanoLC-MS/MS based glycomics approach. In total, 212 N-glycan compositions were identified from the purified UMOD, and 17% were high-mannose glycans, 2% were afucosylated/asialylated, 3% were neutral fucosylated, 28% were sialylated (with no fucose), 46% were fucosylated and sialylated, and 4% were sulfated. We found that isolation of UMOD resulted in a significant decrease in the relative quantity of high-mannose and sulfated glycans with a significant increase of neutral fucosylated glycans in the UMOD-depleted urine relative to the undepleted urine, but depletion had little impact on the sialylated glycans. To our knowledge, this is the first study to perform comprehensive N-glycan profiling of UMOD using nanoLC-MS/MS. This analytical workflow would be very beneficial for studies with limited sample size, such as pediatric studies, and can be applied to larger patient cohorts not only for UMOD interrogation but also for global glycan analysis.

The Complexity and Dynamics of the Tissue Glycoproteome Associated With Prostate Cancer Progression

The complexity and dynamics of the immensely heterogeneous glycoproteome of the prostate cancer (PCa) tumor microenvironment remain incompletely mapped, a knowledge gap that impedes our molecular-level understanding of the disease. To this end, we have used sensitive glycomics and glycoproteomics to map the protein-, cell-, and tumor grade-specific N- and O-glycosylation in surgically removed PCa tissues spanning five histological grades (n = 10/grade) and tissues from patients with benign prostatic hyperplasia (n = 5). Quantitative glycomics revealed PCa grade-specific alterations of the oligomannosidic-, paucimannosidic-, and branched sialylated complex-type N-glycans, and dynamic remodeling of the sialylated core 1- and core 2-type O-glycome. Deep quantitative glycoproteomics identified ∼7400 unique N-glycopeptides from 500 N-glycoproteins and ∼500 unique O-glycopeptides from nearly 200 O-glycoproteins. With reference to a recent Tissue and Blood Atlas, our data indicate that paucimannosidic glycans of the PCa tissues arise mainly from immune cell-derived glycoproteins. Furthermore, the grade-specific PCa glycosylation arises primarily from dynamics in the cellular makeup of the PCa tumor microenvironment across grades involving increased oligomannosylation of prostate-derived glycoproteins and decreased bisecting GlcNAcylation of N-glycans carried by the extracellular matrix proteins. Furthermore, elevated expression of several oligosaccharyltransferase subunits and enhanced N-glycoprotein site occupancy were observed associated with PCa progression. Finally, correlations between the protein-specific glycosylation and PCa progression were observed including increased site-specific core 2-type O-glycosylation of collagen VI. In conclusion, integrated glycomics and glycoproteomics have enabled new insight into the complexity and dynamics of the tissue glycoproteome associated with PCa progression generating an important resource to explore the underpinning disease mechanisms.

N-Glycosylation

N-glycosylation is a highly conserved glycan modification, and more than 7000 proteins are N-glycosylated in humans. N-glycosylation has many biological functions such as protein folding, trafficking, and signal transduction. Thus, glycan modification to proteins is profoundly involved in numerous physiological and pathological processes. The N-glycan precursor is biosynthesized in the endoplasmic reticulum (ER) from dolichol phosphate by sequential enzymatic reactions to generate the dolichol-linked oligosaccharide composed of 14 sugar residues, Glc₃Man₉GlcNAc₂. The oligosaccharide is then en bloc transferred to the consensus sequence N-X-S/T (X represents any amino acid except proline) of nascent proteins. Subsequently, the N-glycosylated nascent proteins enter the folding step, in which N-glycans contribute largely to attaining the correct protein fold by recruiting the lectin-like chaperones, calnexin, and calreticulin. Despite the N-glycan-dependent folding process, some glycoproteins do not fold correctly, and these misfolded glycoproteins are destined to degradation by proteasomes in the cytosol. Properly folded proteins are transported to the Golgi, and N-glycans undergo maturation by the sequential reactions of glycosidases and glycosyltransferases, generating complex-type N-glycans. N-Acetylglucosaminyltransferases (GnT-III, GnT-IV, and GnT-V) produce branched N-glycan structures, affording a higher complexity to N-glycans. In this chapter, we provide an overview of the biosynthetic pathway of N-glycans in the ER and Golgi.

Characterizing human α-1,6-fucosyltransferase (FUT8) substrate specificity and structural similarities with related fucosyltransferases

Mammalian Asn-linked glycans are extensively processed as they transit the secretory pathway to generate diverse glycans on cell surface and secreted glycoproteins. Additional modification of the glycan core by α-1,6-fucose addition to the innermost GlcNAc residue (core fucosylation) is catalyzed by an α-1,6-fucosyltransferase (FUT8). The importance of core fucosylation can be seen in the complex pathological phenotypes of FUT8 null mice, which display defects in cellular signaling, development, and subsequent neonatal lethality. Elevated core fucosylation has also been identified in several human cancers. However, the structural basis for FUT8 substrate specificity remains unknown.Here, using various crystal structures of FUT8 in complex with a donor substrate analog, and with four distinct glycan acceptors, we identify the molecular basis for FUT8 specificity and activity. The ordering of three active site loops corresponds to an increased occupancy for bound GDP, suggesting an induced-fit folding of the donor-binding subsite. Structures of the various acceptor complexes were compared with kinetic data on FUT8 active site mutants and with specificity data from a library of glycan acceptors to reveal how binding site complementarity and steric hindrance can tune substrate affinity. The FUT8 structure was also compared with other known fucosyltransferases to identify conserved and divergent structural features for donor and acceptor recognition and catalysis. These data provide insights into the evolution of modular templates for donor and acceptor recognition among GT-B fold glycosyltransferases in the synthesis of diverse glycan structures in biological systems.

Glycosylation in Indolent, Significant and Aggressive Prostate Cancer by Automated High-Throughput N-Glycan Profiling

The diagnosis and treatment of prostate cancer (PCa) is a major health-care concern worldwide. This cancer can manifest itself in many distinct forms and the transition from clinically indolent PCa to the more invasive aggressive form remains poorly understood. It is now universally accepted that glycan expression patterns change with the cellular modifications that accompany the onset of tumorigenesis. The aim of this study was to investigate if differential glycosylation patterns could distinguish between indolent, significant, and aggressive PCa. Whole serum N-glycan profiling was carried out on 117 prostate cancer patients’ serum using our automated, high-throughput analysis platform for glycan-profiling which utilizes ultra-performance liquid chromatography (UPLC) to obtain high resolution separation of N-linked glycans released from the serum glycoproteins. We observed increases in hybrid, oligomannose, and biantennary digalactosylated monosialylated glycans (M5A1G1S1, M8, and A2G2S1), bisecting glycans (A2B, A2(6)BG1) and monoantennary glycans (A1), and decreases in triantennary trigalactosylated trisialylated glycans with and without core fucose (A3G3S3 and FA3G3S3) with PCa progression from indolent through significant and aggressive disease. These changes give us an insight into the disease pathogenesis and identify potential biomarkers for monitoring the PCa progression, however these need further confirmation studies.

Separation based characterization methods for the N-glycosylation analysis of prostate-specific antigen

Prostate cancer has the highest malignancy rate diagnosed in men worldwide. Albeit, the gold standard serum prostate-specific antigen (PSA) assays reduced the mortality rate of the disease, the number of false positive diagnoses steeply increased. Therefore, there is an urgent need for complementary biomarkers to enhance the specificity and selectivity of current diagnostic methods. Information about PSA glycosylation can help to fulfill this gap as alterations of its carbohydrate moieties due to cancerous transformation may represent additional markers to distinguish malignant from benign tumors. However, development of suitable methods and instrumentations to investigate the N-glycosylation profile of PSA represents a challenge. In this paper, we critically review the current bioanalytical trends and strategies in the field of PSA glycobiomarker research focusing on separation based characterization methods.

Characterisation of the main PSA glycoforms in aggressive prostate cancer

Serum levels of prostate specific antigen (PSA) are commonly used for prostate cancer (PCa) detection. However, their lack of specificity to distinguish benign prostate pathologies from PCa, or indolent from aggressive PCa have prompted the study of new non-invasive PCa biomarkers. Aberrant glycosylation is involved in neoplastic progression and specific changes in PSA glycosylation pattern, as the reduction in the percentage of α2,6-sialic acid (SA) are associated with PCa aggressiveness. In this study, we have characterised the main sialylated PSA glycoforms from blood serum of aggressive PCa patients and have compared with those of standard PSA from healthy individuals’ seminal plasma. PSA was immunoprecipitated and α2,6-SA were separated from α2,3-SA glycoforms using SNA affinity chromatography. PSA N-glycans were released, labelled and analysed by hydrophilic interaction liquid chromatography combined with exoglycosidase digestions. The results showed that blood serum PSA sialylated glycoforms containing GalNAc residues were largely increased in aggressive PCa patients, whereas the disialylated core fucosylated biantennary structures with α2,6-SA, which are the major PSA glycoforms in standard PSA from healthy individuals, were markedly reduced in aggressive PCa. The identification of these main PSA glycoforms altered in aggressive PCa opens the way to design specific strategies to target them, which will be useful to improve PCa risk stratification.

Analysis of serum glycome by lectin microarrays for prostate cancer patients - a search for aberrant glycoforms

This is the first work focused on glycoprofiling of whole N- and O- glycome using lectins in an array format applied for analysis of serum samples from healthy individuals, benign prostate hyperplasia (BPH) patients, and prostate cancer (PCa) patients. Lectin microarray was prepared using traditional lectins with the incorporation of 2 recombinant bacterial lectins and 3 human lectins (17 lectins in total). Clinical validation of glycans as biomarkers was done in two studies: discrimination of healthy individuals with BPH patients vs. PCa patients (C vs. PCa) and discrimination of healthy individuals vs. BPH and PCa patients (H vs. PCond). Single lectins (17 lectins) and a combination of two lectins (136 binary lectin combinations) were applied in the clinical validation of glycan biomarkers providing 153 AUC values from ROC curves for both studies (C vs. PCa and H vs. PCond). Potential N- and O-glycans as biomarkers were identified and possible carriers of these glycans are shortly discussed.

Glycan array analysis of Pholiota squarrosa lectin and other fucose-oriented lectins

The α(1,6)fucose residue attached to the N-glycoprotein core is suspected to play an essential role in the progression of several types of cancer. Lectins remain the first choice for probing glycan modifications, although they may lack specificity. Thus, efforts have been made to identify new lectins with a narrower core fucose (CF) detection profile. Here, we present a comparison of the classical Aleuria aurantia lectin (AAL), Lens culinaris agglutinin (LCA) and Aspergillus oryzae lectin (AOL) with the newer Pholiota squarrosa lectin (PhoSL), which has been described as being specific for core fucosylated N-glycans. To this end, we studied the binding profiles of the four lectins using mammalian glycan arrays from the Consortium of Functional Glycomics. To validate their glycan specificity, we probed AOL, LCA and PhoSL in western-blot assays using protein extracts from eight common colorectal cancer (CRC) lines and colorectal biopsies from a small cohort of patients with CRC. The results showed that (i) LCA and PhoSL were the most specific lectins for detecting the presence of CF in a concentration-dependent manner; (ii) PhoSL exhibited the highest N-glycan sequence restriction, with preferential binding to core fucosylated paucimannosidic-type N-glycans, (iii) the recognition ability of PhoSL was highly influenced by the presence of terminal N-acetyl-lactosamine; (iv) LCA bound to paucimannosidic, bi-antennary and tri-antennary core fucosylated N-glycans and (v) AOL and AAL exhibited broader specificity towards fucosylation. Together, our results support the choice of LCA as the most appropriate lectin for CF detection, as validated in protein extracts from CRC cell lines and tissue specimens from patients with CRC.

Assessment of ICAM-1 N-glycoforms in mouse and human models of endothelial dysfunction

Endothelial dysfunction is a critical event in vascular inflammation characterized, in part, by elevated surface expression of adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1). ICAM-1 is heavily N-glycosylated, and like other surface proteins, it is largely presumed that fully processed, complex N-glycoforms are dominant. However, our recent studies suggest that hypoglycosylated or high mannose (HM)-ICAM-1 N-glycoforms are also expressed on the cell surface during endothelial dysfunction, and have higher affinity for monocyte adhesion and regulate outside-in endothelial signaling by different mechanisms. Whether different ICAM-1 N-glycoforms are expressed in vivo during disease is unknown. In this study, using the proximity ligation assay, we assessed the relative formation of high mannose, hybrid and complex α-2,6-sialyated N-glycoforms of ICAM-1 in human and mouse models of atherosclerosis, as well as in arteriovenous fistulas (AVF) of patients on hemodialysis. Our data demonstrates that ICAM-1 harboring HM or hybrid epitopes as well as ICAM-1 bearing α-2,6-sialylated epitopes are present in human and mouse atherosclerotic lesions. Further, HM-ICAM-1 positively associated with increased macrophage burden in lesions as assessed by CD68 staining, whereas α-2,6-sialylated ICAM-1 did not. Finally, both HM and α-2,6-sialylated ICAM-1 N-glycoforms were present in hemodialysis patients who had AVF maturation failure compared to successful AVF maturation. Collectively, these data provide evidence that HM- ICAM-1 N-glycoforms are present in vivo, and at levels similar to complex α-2,6-sialylated ICAM-1 underscoring the need to better understand their roles in modulating vascular inflammation.

HILIC-MRM-MS for Linkage-Specific Separation of Sialylated Glycopeptides to Quantify Prostate-Specific Antigen Proteoforms

Elevated serum prostate-specific antigen (PSA) levels in body fluids may indicate prostate cancer (PCa), but it is noted that the clinical performance is rather poor. Specificity and sensitivity values of 20 and 94% at a cutoff value of 4.1 ng/mL, respectively, result in overdiagnosis and unnecessary interventions. Previous exploratory studies have indicated that the glycosylation of PSA potentially leads to improved PCa diagnosis based on qualitative analyses. However, the applied methods are not suited for a quantitative evaluation or implementation in a medical laboratory. Therefore, in this proof-of-principle study, we have evaluated the use of hydrophilic interaction liquid chromatography (HILIC) in combination with targeted quantitative mass spectrometry for the sialic acid linkage-specific analysis of PSA glyco-proteoforms based on either trypsin or ArgC peptides. The efficiency of PSA proteolysis was optimized as well as the glycopeptide separation conditions (buffer type, strength, and pH). The HILIC-based analysis of PSA glyco-proteoforms presented here has the potential for the clinical validation of patient cohorts. The method shows the feasibility of the use of a HILIC stationary phase for the separation of isomeric glycopeptides to detect specific glyco-proteoforms. This is the first step toward the development and evaluation of PSA glyco-proteoforms for use in a clinical chemistry setting aiming for improved PCa diagnosis or screening.

Biomimetic nanochannels for the discrimination of sialylated glycans via a tug-of-war between glycan binding and polymer shrinkage

Sialylated glycans that are attached to cell surface mediate diverse cellular processes such as immune responses, pathogen binding, and cancer progression. Precise determination of sialylated glycans, particularly their linkage isomers that can trigger distinct biological events and are indicative of different cancer types, remains a challenge, due to their complicated composition and limited structural differences. Here, we present a biomimetic nanochannels system integrated with the responsive polymer polyethyleneimine-g-glucopyranoside (Glc-PEI) to solve this problem. By using a dramatic “OFF–ON” change in ion flux, the nanochannels system achieves specific recognition for N-acetylneuraminic acid (Neu5Ac, the predominant form of sialic acid) from various monosaccharides and sialic acid species. Importantly, different “OFF–ON” ratios of the conical nanochannels system allows the precise and sensitive discrimination of sialylated glycan linkage isomers, α2–3 and α2–6 linkage (the corresponding ion conductance increase ratios are 96.2% and 264%, respectively). Analyses revealed an unusual tug-of-war mechanism between polymer-glycan binding and polymer shrinkage. The low binding affinity of Glc-PEI for the α2–6-linked glycan caused considerable shrinkage of Glc-PEI layer, but the high affinity for the α2–3-linked glycan resulted in only a slight shrinkage. This competition mechanism provides a simple and versatile materials design principle for recognition or sensing systems that involve negatively charged target biomolecules. Furthermore, this work broadens the application of nanochannel systems in bioanalysis and biosensing, and opens a new route to glycan analysis that could help to uncover the mysterious and wonderful glycoworld.

A glycan-responsive polymer-modified nanochannels system enables the precise discrimination of sialylated glycan linkage isomers via the different “OFF–ON” changes resulting from a “tug-of-war” between polymer-glycan binding and polymer shrinkage.

Integrated Transcriptomics, Proteomics, and Glycomics Reveals the Association between Up-regulation of Sialylated N-glycans/Integrin and Breast Cancer Brain Metastasis

Breast cancer brain metastasis has been recognized as one of the central issues in breast cancer research. The elucidation of the processes and pathways that mediate this step will provide important clues for a better understanding of breast cancer metastasis. Increasing evidence suggests that aberrant glycosylation patterns greatly contribute to cell invasion and cancer metastasis. Herein, we combined next-generation RNA sequencing with liquid chromatography-tandem mass spectrometry-based proteomic and N-glycomic analysis from five breast cancer cell lines and one brain cancer cell line to investigate the possible mechanisms of breast cancer brain metastasis. The genes/proteins associated with cell movement were highlighted in breast cancer brain metastasis. The integrin signaling pathway and the up-regulation of α-integrin (ITGA2, ITGA3) were associated with the brain metastatic process. 12 glycogenes showed unique expression in 231BR, which could result in an increase of sialylation during brain metastasis. In agreement with the changes of glycogenes, 60 out of 63 N-glycans that were identified exhibited differential expression among cell lines. The correlation between glycogenes and glycans revealed the importance of sialylation and sialylated glycans in breast cancer brain metastasis. Highly sialylated N-glycans, which were up-regulated in brain-seeking cell line 231BR, likely play a role in brain metastasis.

Altered N-glycan profile of IgG-depleted serum proteins in Hashimoto's thyroiditis

BACKGROUND

Hashimoto's thyroiditis (HT) is an autoimmune disease characterized by chronic inflammation of thyroid gland. Although HT is the most common cause of hypothyroidism, the pathogenesis of this disease is not fully understood. Glycosylation of serum proteins was examined in HT only to a limited extent. The study was designed to determine the glycosylation pattern of IgG-depleted sera from HT patients.

METHODS

Serum N-glycans released by N-glycosidase F (PNGase F) digestion were analyzed by normal-phase high-performance liquid chromatography (NP-HPLC). N-glycan structures in each collected HPLC fraction were determined by liquid chromatography-mass spectrometry (LC-MS) and exoglycosidase digestion. Fucosylation and sialylation was also analyzed by lectin blotting.

RESULTS

The results showed an increase of monosialylated tri-antennary structure (A3G3S1) and disialylated diantennary N-glycan with antennary fucose (FA2G2S2). Subsequently, we analyzed the serum N-glycan profile by lectin blotting using lectins specific for fucose and sialic acid. We found a significant decrease of Lens culinaris agglutinin (LCA) staining in HT samples, which resulted from the reduction of α1,6-linked core fucose in HT serum. We also observed an increase of Maackia amurensis II lectin (MAL-II) reaction in HT due to the elevated level of α2,3-sialylation in HT sera.

CONCLUSIONS

The detected alterations of serum protein sialylation might be caused by chronic inflammation in HT. The obtained results complete our previous IgG N-glycosylation analysis in autoimmune thyroid patients and show that the altered N-glycosylation of serum proteins is characteristic for autoimmunity process in HT. General Significance Thyroid autoimmunity is accompanied by changes of serum protein sialylation.

Contribution of sialic acids to integrin α5β1 functioning in melanoma cells

PURPOSE

To establish the relationship between sialylation of integrin α5β1 and possible alteration in the function of α5β1 receptor in melanoma cells.

MATERIALS AND METHODS

Integrin α5β1 was isolated from primary WM115 (RGP/VGP-like phenotype) and metastatic WM266-4 (lymph node metastasis) cells via affinity chromatography. Integrin α5β1 sialylation and the shift in relative masses of the enzymatically desialylated subunits were confirmed by confocal microscopy and SDS-PAGE, respectively. The ELISA assay was performed to evaluate sialic acid (SA) influence on integrin α5β1 binding to fibronectin (FN). Cell invasion was investigated by the Transwell invasion assay. The effect of neuraminidases treatment on melanoma cells was assessed by flow cytometry using Maackia amurensis and Sambucus nigra lectins.

RESULTS

Both subunits of integrin α5β1 were found to be more abundantly sialylated in primary than in metastatic cells. The removal of SA had no effect on the purified integrin α5β1 binding to FN. Although metastatic cells underwent more pronounced desialylation than primary cells, invasion of primary WM115 cells was more dependent on the presence of α2-3 linked SA than it was in the case of metastatic WM266-4 cells. In both melanoma cell lines not only integrin α5β1 was involved in invasion, however simultaneous desialylation and usage of anti-integrin α5β1 antibodies resulted in lower invasion abilities of primary WM115 cells.

CONCLUSIONS

Our data suggest that in primary melanoma cells integrin α5β1 action is more likely dependent on its glycosylation profile, i.e. the presence of SA residues, which influence (decreased) their invasion properties and may facilitate malignant melanoma progression.

The Diverse Contributions of Fucose Linkages in Cancer

Fucosylation is a post-translational modification of glycans, proteins, and lipids that is responsible for many biological processes. Fucose conjugation via α(1,2), α(1,3), α(1,4), α(1,6), and O'- linkages to glycans, and variations in fucosylation linkages, has important implications for cancer biology. This review focuses on the roles that fucosylation plays in cancer, specifically through modulation of cell surface proteins and signaling pathways. How L-fucose and serum fucosylation patterns might be used for future clinical diagnostic, prognostic, and therapeutic approaches will be discussed.