Glycosylation change of alpha-1-acid glycoprotein as a serum biomarker for hepatocellular carcinoma and cirrhosis

Increased Siglec-9/Siglec-9L interactions on NK cells predict poor HCC prognosis and present a targetable checkpoint for immunotherapy

BACKGROUND & AIMS

Natural killer (NK) cell-based anti-hepatocellular carcinoma (HCC) therapy is an increasingly attractive approach that warrants further study. Siglec-9 interacts with its ligand (Siglec-9L) and restrains NK cell functions, suggesting it is a potential therapeutic target. However, in situ Siglec-9/Siglec-9L interactions in HCC have not been reported, and a relevant interventional strategy is lacking. Herein, we aim to illustrate Siglec-9/Siglec-9L-mediated cell sociology and identify small-molecule inhibitors targeting Siglec-9 that could improve the efficacy of NK cell-based immunotherapy for HCC.

METHODS

Multiplexed immunofluorescence staining was performed to analyze the expression pattern of Siglec-7, -9 and their ligands in HCC tissues. Then we conducted docking-based virtual screening combined with bio-layer interferometry assays to identify a potent small-molecule Siglec-9 inhibitor. The therapeutic potential was further evaluated in vitro and in hepatoma-bearing NCG mice.

RESULTS

Siglec-9 expression, rather than Siglec-7, was markedly upregulated on tumor-infiltrating NK cells, which correlated significantly with reduced survival of patients with HCC. Moreover, the number of Siglec-9L+ cells neighboring Siglec-9+ NK cells was increased in HCC tissues and was also associated with tumor recurrence and reduced survival, further suggesting that Siglec-9/Siglec-9L interactions are a potential therapeutic target in HCC. In addition, we identified a small-molecule Siglec-9 inhibitor MTX-3937 which inhibited phosphorylation of Siglec-9 and downstream SHP1 and SHP2. Accordingly, MTX-3937 led to considerable improvement in NK cell function. Notably, MTX-3937 enhanced cytotoxicity of both human peripheral and tumor-infiltrating NK cells. Furthermore, transfer of MTX-3937-treated NK92 cells greatly suppressed the growth of hepatoma xenografts in NCG mice.

CONCLUSIONS

Our study provides the rationale for HCC treatment by targeting Siglec-9 on NK cells and identifies a promising small-molecule inhibitor against Siglec-9 that enhances NK cell-mediated HCC surveillance.

IMPACT AND IMPLICATIONS

Herein, we found that Siglec-9 expression is markedly upregulated on tumor-infiltrating natural killer (TINK) cells and correlates with reduced survival in patients with hepatocellular carcinoma (HCC). Moreover, the number of Siglec-9L+ cells neighboring Siglec-9+ NK cells was increased in HCC tissues and was also associated with tumor recurrence and reduced survival. More importantly, we identified a small-molecule inhibitor targeting Siglec-9 that augments NK cell functions, revealing a novel immunotherapy strategy for liver cancer that warrants further clinical investigation.

Diagnostic and Prognostic Value of Protein Post-translational Modifications in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common malignant tumor with high incidence and cancer mortality worldwide. Post-translational modifications (PTMs) of proteins have a great impact on protein function. Almost all proteins can undergo PTMs, including phosphorylation, acetylation, methylation, glycosylation, ubiquitination, and so on. Many studies have shown that PTMs are related to the occurrence and development of cancers. The findings provide novel therapeutic targets for cancers, such as glypican-3 and mucin-1. Other clinical implications are also found in the studies of PTMs. Diagnostic or prognostic value, and response to therapy have been identified. In HCC, it has been shown that glycosylated alpha-fetoprotein (AFP) has a higher detection rate for early liver cancer than conventional AFP. In this review, we mainly focused on the diagnostic and prognostic value of PTM, in order to provide new insights into the clinical implication of PTM in HCC.

Hepatocellular carcinoma: Preclinical and clinical applications of nanotechnology with the potential role of carbohydrate receptors

Hepatocellular carcinoma (HCC) is one of the most common types of liver cancer; accounts for 75-85% of cases. The treatment and management of HCC involve different sanative options like surgery, chemotherapy, immunotherapy, etc. Recently, various advancements have been introduced for the diagnosis and targeting of hepatic tumor cells. Among these, biomarkers are considered the primary source for the diagnosis and differentiation of tumor cells. With the advancement in the field of nanotechnology, different types of nanocarriers have been witnessed in tumor targeting. Nanocarriers such as nanoparticles, liposomes, polymeric micelles, nanofibers, etc. are readily prepared for effective tumor targeting with minimal side-effects. The emergence of various approaches tends to improve the effectiveness of these nanocarriers as demonstrated in ample clinical trials. This review focuses on the significant role of carbohydrates such as mannose, galactose, fructose, etc. in the development, diagnosis, and therapy of HCC. Hence, the current focus of this review is to acknowledge various perspectives regarding the occurrence, diagnosis, treatment, and management of HCC.

Recent Insights into the Biomarkers, Molecular Targets and Mechanisms of Non-Alcoholic Steatohepatitis-Driven Hepatocarcinogenesis

Non-alcoholic fatty liver disease (NAFLD) or metabolic dysfunction-associated steatotic liver disease (MASLD) and steatohepatitis (NASH) are chronic hepatic conditions leading to hepatocellular carcinoma (HCC) development. According to the recent "multiple-parallel-hits hypothesis", NASH could be caused by abnormal metabolism, accumulation of lipids, mitochondrial dysfunction, and oxidative and endoplasmic reticulum stresses and is found in obese and non-obese patients. Recent translational research studies have discovered new proteins and signaling pathways that are involved not only in the development of NAFLD but also in its progression to NASH, cirrhosis, and HCC. Nevertheless, the mechanisms of HCC developing from precancerous lesions have not yet been fully elucidated. Now, it is of particular importance to start research focusing on the discovery of novel molecular pathways that mediate alterations in glucose and lipid metabolism, which leads to the development of liver steatosis. The role of mTOR signaling in NASH progression to HCC has recently attracted attention. The goals of this review are (1) to highlight recent research on novel genetic and protein contributions to NAFLD/NASH; (2) to investigate how recent scientific findings might outline the process that causes NASH-associated HCC; and (3) to explore the reliable biomarkers/targets of NAFLD/NASH-associated hepatocarcinogenesis.

The hidden potential of glycomarkers: Glycosylation studies in the service of cancer diagnosis and treatment

Changes in the glycosylation process appear early in carcinogenesis and evolve with the growth and spread of cancer. The correlation of the characteristic glycosylation signature with the tumor stage and the appropriate therapy choice is an important issue in translational medicine. Oncologists also pay attention to extracellular vesicles as reservoirs of new cancer glycomarkers that can be potent for cancer diagnosis/prognosis. In this review, we recall glycomarkers used in oncology and show their new glycoforms of improved clinical relevance. We summarize current knowledge on the biological functions of glycoepitopes in cancer-derived extracellular vesicles and their potential use in clinical practice. Is glycomics a future of cancer diagnosis? It may be, but in combination with other omics analyses than alone.

Updating the Clinical Application of Blood Biomarkers and Their Algorithms in the Diagnosis and Surveillance of Hepatocellular Carcinoma: A Critical Review

The most common primary liver cancer is hepatocellular carcinoma (HCC), and its mortality rate is increasing globally. The overall 5-year survival of patients with liver cancer is currently 10-20%. Moreover, because early diagnosis can significantly improve prognosis, which is highly correlated with tumor stage, early detection of HCC is critical. International guidelines advise using α-FP biomarker with/without ultrasonography for HCC surveillance in patients with advanced liver disease. However, traditional biomarkers are sub-optimal for risk stratification of HCC development in high-risk populations, early diagnosis, prognostication, and treatment response prediction. Since about 20% of HCCs do not produce α-FP due to its biological diversity, combining α-FP with novel biomarkers can enhance HCC detection sensitivity. There is a chance to offer promising cancer management methods in high-risk populations by utilizing HCC screening strategies derived from new tumor biomarkers and prognostic scores created by combining biomarkers with distinct clinical parameters. Despite numerous efforts to identify molecules as potential biomarkers, there is no single ideal marker in HCC. When combined with other clinical parameters, the detection of some biomarkers has higher sensitivity and specificity in comparison with a single biomarker. Therefore, newer biomarkers and models, such as the Lens culinaris agglutinin-reactive fraction of Alpha-fetoprotein (α-FP), α-FP-L3, Des-γ-carboxy-prothrombin (DCP or PIVKA-II), and the GALAD score, are being used more frequently in the diagnosis and prognosis of HCC. Notably, the GALAD algorithm was effective in HCC prevention, particularly for cirrhotic patients, regardless of the cause of their liver disease. Although the role of these biomarkers in surveillance is still being researched, they may provide a more practical alternative to traditional imaging-based surveillance. Finally, looking for new diagnostic/surveillance tools may help improve patients' survival. This review discusses the current roles of the most used biomarkers and prognostic scores that may aid in the clinical management of HCC patients.

Screening and verification of genes related to polycystic ovary syndrome

OBJECTIVE

To identify key genes involved in occurrence and development of polycystic ovary syndrome (PCOS).

METHODS

By downloading the GSE85932 dataset from the GEO database, we used bioinformatical analysis to analyse differentially expressed genes (DEGs) from blood samples of eight women with PCOS and eight matched controls. Following bioinformatic analysis, we performed a cross-sectional study of serum samples taken from 79 women with PCOS and 36 healthy controls.

RESULTS

From the 178 DEGs identified by bioinformatical analysis, 15 genes were identified as significant, and of these, ORM1 and ORM2 were selected for further verification as potential biomarkers for PCOS. Serum ORM1 and ORM2 levels were significantly increased in women with PCOS, and had a high diagnostic value. ORM1 and ORM2 were positively correlated with testosterone, cholesterol, and triglycerides. ORM1 levels were negatively correlated with high density lipoprotein (HDL) while ORM2 levels showed no significant correlation.

CONCLUSIONS

ORM may be an effective biomarker for the diagnosis of PCOS and its monitoring may be a useful therapeutic strategy.

Serum Glycoprotein Markers in Nonalcoholic Steatohepatitis and Hepatocellular Carcinoma

Fatty liver disease progresses through stages of fat accumulation and inflammation to nonalcoholic steatohepatitis (NASH), fibrosis and cirrhosis, and eventually hepatocellular carcinoma (HCC). Currently available diagnostic tools for HCC lack sensitivity and specificity. In this study, we investigated the use of circulating serum glycoproteins to identify a panel of potential prognostic markers that may be indicative of progression from the healthy state to NASH and further to HCC. Serum samples were processed and analyzed using a novel high-throughput glycoproteomics platform. Our initial dataset contained healthy, NASH, and HCC serum samples. We analyzed 413 glycopeptides, representing 57 abundant serum proteins, and compared among the three phenotypes. We studied the normalized abundance of common glycoforms and found 40 glycopeptides with statistically significant differences in abundances in NASH and HCC compared to controls. Summary level relative abundances of core-fucosylated, sialylated, and branched glycans containing glycopeptides were higher in NASH and HCC as compared to controls. We replicated some of our findings in an independent set of samples of individuals with benign liver conditions and HCC. Our results may be of value in the management of liver diseases. Data generated in this work can be downloaded from MassIVE (https://massive.ucsd.edu) with identifier MSV000088809.

Integrated GWAS and Gene Expression Suggest ORM1 as a Potential Regulator of Plasma Levels of Cell-Free DNA and Thrombosis Risk

Plasma cell-free DNA (cfDNA) is a surrogate marker of neutrophil extracellular traps (NETs) that contribute to immunothrombosis. There is growing interest about the mechanisms underlying NET formation and elevated cfDNA, but little is known about the factors involved. We aimed to identify genes involved in the regulation of cfDNA levels using data from the Genetic Analysis of Idiopathic Thrombophilia (GAIT-2) Project.

Imputed genotypes, whole blood RNA-Seq data, and plasma cfDNA quantification were available for 935 of the GAIT-2 participants from 35 families with idiopathic thrombophilia. We performed heritability and GWAS analysis for cfDNA. The heritability of cfDNA was 0.26 ( p  = 3.7 × 10 ⁻⁶ ), while the GWAS identified a significant association (rs1687391, p  = 3.55 × 10 ⁻¹⁰ ) near the ORM1 gene, on chromosome 9. An eQTL (expression quantitative trait loci) analysis revealed a significant association between the lead GWAS variant and the expression of ORM1 in whole blood ( p  = 6.14 × 10 ⁻⁹ ). Additionally, ORM1 expression correlated with levels of cfDNA ( p  = 4.38 × 10 ⁻⁴ ). Finally, genetic correlation analysis between cfDNA and thrombosis identified a suggestive association ( ρ_g  = 0.43, p  = 0.089).

All in all, we show evidence of the role of ORM1 in regulating cfDNA levels in plasma, which might contribute to the susceptibility to thrombosis through mechanisms of immunothrombosis.

Orosomucoid in liver diseases

In this editorial, the roles of orosomucoid (ORM) in the diagnoses and follow-up assessments of both nonneoplastic diseases and liver tumors are discussed with respect to the publication by Zhu et al presented in the previous issue of World Journal of Gastroenterology (2020; 26(8): 840-817). ORM, or alpha-1 acid glycoprotein (AGP), is an acute-phase protein that constitutes 1% to 3% of plasma proteins in humans and is mainly synthesized in the liver. ORM exists in serum as two variants: ORM1 and ORM2. Although the variants share 89.6% sequence identity and have similar biological properties, ORM1 constitutes the main component of serum ORM. An interesting feature of ORM is that its biological effects differ according to variations in glycosylation patterns. This variable feature makes ORM an attractive target for diagnosing and monitoring many diseases, including those of the liver. Recent findings suggest that a sharp decrease in ORM level is an important marker for HBV-associated acute liver failure (ALF), and ORM1 plays an important role in liver regeneration. In viral hepatitis, increases in both ORM and its fucosylated forms and the correlation of these increases with fibrosis progression suggest that this glycoprotein can be used with other markers as a noninvasive method in the follow-up assessment of diseases. In addition, similar findings regarding the level of the asialylated form of ORM, called asialo-AGP (AsAGP), have been reported in a follow-up assessment of fibrosis in chronic liver disease. An increase in ORM in serum has also been shown to improve hepatocellular carcinoma (HCC) diagnosis performance when combined with other markers. In addition, determination of the ORM level has been useful in the diagnosis of HCC with AFP concentrations less than 500 ng/mL. For monitoring patients with AFP-negative HCC, a unique trifucosylated tetra-antennary glycan of ORM may also be used as a new potential marker. The fact that there are very few studies investigating the expression of this glycoprotein and its variants in liver tissues constitutes a potential limitation, especially in terms of revealing all the effects of ORM on carcinogenesis and tumor behavior. Current findings indicate that ORM2 expression is decreased in tumors, and this is related to the aggressive course of the disease. Parallel to this finding, in HCC cell lines, ORM2 decreases HCC cell migration and invasion, supporting reports of its tumor suppressor role. In conclusion, the levels of ORM and its different glycosylated variants are promising additional biomarkers for identifying ALF, for monitoring fibrosis in viral hepatitis, and for diagnosing early HCC. Although there is evidence that the loss of ORM2 expression in HCC is associated with poor prognosis, further studies are needed to support these findings. Additionally, investigations of ORM expression in borderline dysplastic nodules and hepatocellular adenomas, which pose diagnostic problems in the differential diagnosis of HCC, especially in biopsy samples, may shed light on whether ORM can be used in histopathological differential diagnosis.

Altered Glycosylation of Human Alpha-1-Acid Glycoprotein as a Biomarker for Malignant Melanoma

A high-resolution HILIC-MS/MS method was developed to analyze anthranilic acid derivatives of N-glycans released from human serum alpha-1-acid glycoprotein (AGP). The method was applied to samples obtained from 18 patients suffering from high-risk malignant melanoma as well as 19 healthy individuals. It enabled the identification of 102 glycan isomers separating isomers that differ only in sialic acid linkage (α-2,3, α-2,6) or in fucose positions (core, antenna). Comparative assessment of the samples revealed that upregulation of certain fucosylated glycans and downregulation of their nonfucosylated counterparts occurred in cancer patients. An increased ratio of isomers with more α-2,6-linked sialic acids was also observed. Linear discriminant analysis (LDA) combining 10 variables with the highest discriminatory power was employed to categorize the samples based on their glycosylation pattern. The performance of the method was tested by cross-validation, resulting in an overall classification success rate of 96.7%. The approach presented here is significantly superior to serological marker S100B protein in terms of sensitivity and negative predictive power in the population studied. Therefore, it may effectively support the diagnosis of malignant melanoma as a biomarker.

Advances in the discovery of novel biomarkers for cancer: spotlight on protein N-glycosylation

Progress on glycosylation and tumor markers has not been extensively reported. Glycosylation plays an important part in post-translational modification. Previous research on glycosylation-modified biomarkers has lagged behind due to insufficient understanding of glycosylation-related regulations. However, some new methods and ideas illustrated in recent research may provide new inspirations in the field. This article aims to review current advances in revealing relationship between tumors and abnormal N-glycosylation and discuss leading-edge applications of N-glycosylation in developing novel tumor biomarkers.

On the binding reaction of loratadine with human serum acute phase protein alpha 1-acid glycoprotein

Loratadine is an important anti-allergic drug. It is a second generation antihistamine drug used to treat allergic rhinitis, hay fever and urticaria. Human serum alpha 1-acid glycoprotein (AG) is an important acute phase protein and its serum concentration is found to increase in inflammation and acute response.The binding interaction between loratadine and AG is studied using spectroscopy and molecular docking techniques. The results obtained from fluorescence quenching experiments demonstrated that the fluorescence intensity of AG is quenched by loratadine. Loratadine was found to bind AG with the binding constant of ≈10⁴ at 298 K. The Gibb's free energy change was found to be negative for the interaction of loratadine with AG indicating the binding process is spontaneous. Binding of loratadine with AG induced ordered structures in the protein. Hydrogen bonding and hydrophobic interactions were the main bonding forces between AG-loratadine as revealed by molecular docking results. This study suggests the importance of binding of anti-allergic drug to AG spatially in the diseases where the plasma concentration of AG increases many folds and interaction with this protein becomes significant. This study will help in design of drug dosage and adjustment accordingly to achieve optimal treatment outcome. Communicated by Ramaswamy H. Sarma.

High-Throughput and Site-Specific N-Glycosylation Analysis of Human Alpha-1-Acid Glycoprotein Offers a Great Potential for New Biomarker Discovery

Alpha-1-acid glycoprotein (AGP) is an acute phase glycoprotein in blood, which is primarily synthetized in the liver and whose biological role is not completely understood. It consists of 45% carbohydrates that are present in the form of five N-linked complex glycans. AGP N-glycosylation was shown to be changed in many different diseases, and some changes appear to be disease-specific; thus, it has a great diagnostic and prognostic potential. However, AGP glycosylation was mainly analyzed in small cohorts and without detailed site-specific glycan information. Here, we developed a cost-effective method for a high-throughput and site-specific N-glycosylation LC-MS analysis of AGP which can be applied on large cohorts, aid in search for novel disease biomarkers, and enable better understanding of AGP's role and function in health and disease. The method does not require isolation of AGP with antibodies and affinity chromatography, but AGP is enriched by acid precipitation from 5 μl of bloodplasma in a 96-well format. After trypsinization, AGP glycopeptides are purified using a hydrophilic interaction chromatography-based solid-phase extraction and analyzed by reversed-phase-liquid chromatography-electrospray ionization-MS. We used our method to show for the first time that AGP N-glycan profile is stable in healthy individuals (14 individuals in three time points), which is a requirement for evaluation of its diagnostic potential. Furthermore, we tested our method on a population including individuals with registered hyperglycemia in critical illness (59 cases and 49 controls), which represents a significantly increased risk of developing type 2 diabetes. Individuals at higher risk of diabetes presented increased N-glycan branching on AGP's second glycosylation site and lower sialylation of N-glycans on AGP's third and AGP1's fourth glycosylation site. Although this should be confirmed on a larger prospective cohort, it indicates that site-specific AGP N-glycan profile could help distinguish individuals who are at risk of type 2 diabetes.

Screening for abnormal glycosylation in a cohort of adult liver disease patients

Congenital disorders of glycosylation (CDG) are a rapidly expanding group of rare genetic defects in glycosylation. In a novel CDG subgroup of vacuolar-ATPase (V-ATPase) assembly defects, various degrees of hepatic injury have been described, including end-stage liver disease. However, the CDG diagnostic workflow can be complex as liver disease per se may be associated with abnormal glycosylation. Therefore, we collected serum samples of patients with a wide range of liver pathology to study the performance and yield of two CDG screening methods. Our aim was to identify glycosylation patterns that could help to differentiate between primary and secondary glycosylation defects in liver disease. To this end, we analyzed serum samples of 1042 adult liver disease patients. This cohort consisted of 567 liver transplant candidates and 475 chronic liver disease patients. Our workflow consisted of screening for abnormal glycosylation by transferrin isoelectric focusing (tIEF), followed by in-depth analysis of the abnormal samples with quadruple time-of-flight mass spectrometry (QTOF-MS). Screening with tIEF resulted in identification of 247 (26%) abnormal samples. QTOF-MS analysis of 110 of those did not reveal glycosylation abnormalities comparable with those seen in V-ATPase assembly factor defects. However, two patients presented with isolated sialylation deficiency. Fucosylation was significantly increased in liver transplant candidates compared to healthy controls and patients with chronic liver disease. In conclusion, a significant percentage of patients with liver disease presented with abnormal CDG screening results. However, the glycosylation pattern was not indicative for a V-ATPase assembly factor defect. Advanced glycoanalytical techniques assist in the dissection of secondary and primary glycosylation defects.

Different glycoforms of alpha-1-acid glycoprotein contribute to its functional alterations in platelets and neutrophils

Alpha-1-acid glycoprotein (AGP-1) is a positive acute phase glycoprotein with uncertain functions. Serum AGP-1 (sAGP-1) is primarily derived from hepatocytes and circulates as 12-20 different glycoforms. We isolated a glycoform secreted from platelet-activating factor (PAF)-stimulated human neutrophils (nAGP-1). Its peptide sequence was identical to hepatocyte-derived sAGP-1, but nAGP-1 differed from sAGP-1 in its chromatographic behavior, electrophoretic mobility, and pattern of glycosylation. The function of these 2 glycoforms also differed. sAGP-1 activated neutrophil adhesion, migration, and neutrophil extracellular traps (NETosis) involving myeloperoxidase, peptidylarginine deiminase 4, and phosphorylation of ERK in a dose-dependent fashion, whereas nAGP-1 was ineffective as an agonist for these events. Furthermore, sAGP-1, but not nAGP-1, inhibited LPS-stimulated NETosis. Interestingly, nAGP-1 inhibited sAGP-1-stimulated neutrophil NETosis. The discordant effect of the differentially glycosylated AGP-1 glycoforms was also observed in platelets where neither of the AGP-1 glycoforms alone stimulated aggregation of washed human platelets, but sAGP-1, and not nAGP-1, inhibited aggregation induced by PAF or ADP, but not by thrombin. These functional effects of sAGP-1 correlated with intracellular cAMP accumulation and phosphorylation of the protein kinase A substrate vasodilator-stimulated phosphoprotein and reduction of Akt, ERK, and p38 phosphorylation. Thus, the sAGP-1 glycoform limits platelet reactivity, whereas nAGP-1 glycoform also limits proinflammatory actions of sAGP-1. These studies identify new functions for this acute phase glycoprotein and demonstrate that the glycosylation of AGP-1 controls its effects on 2 critical cells of acute inflammation.

Association between α1-antitrypsin and acute coronary syndrome

α1-antitrypsin (AAT) is a protein released as part of the anti-inflammatory response. It regulates the activity of serine proteinases and has a crucial role in the pathogenesis of acute coronary syndrome (ACS). The present study aimed to examine its role in patients with ACS. The plasma samples of 117 patients were collected at the Cardiology Department of the Affiliated Hospital of Youjiang Medical University (Baise, China). These included 46 cases of ACS (who met the diagnostic criteria for ACS and had ≥50% luminal stenosis of any coronary vessel), 35 cases of stable angina (SA; with ≥50% luminal stenosis of any coronary vessel but in a stable condition) and 36 normal healthy controls (subjects with no luminal stenosis in their coronary arteries). Plasma AAT protein concentrations were measured by ELISA and clinical data were collected. The plasma levels of AAT protein in patients with ACS were lower than those in controls and cases of SA (P<0.05), and the levels tended to decrease with the number of coronary artery lesions involved. There were no significant associations of the expression of plasma AAT protein and the number of diseased vessels in patients or the degree of stenosis. There was no correlation between the plasma protein levels of AAT and Gensini scores of patients with ACS. In conclusion, the plasma AAT protein levels in patients with ACS may contribute to the occurrence and development of coronary artery disease.

Serum Levels and Glycosylation Changes of Alpha-1-Acid Glycoprotein According to Severity of Breast Cancer in Korean Women

Elevated serum levels of alpha-1-acid glycoprotein (AGP) are known to be associated with several types of cancer. In addition, some reports have indicated that changes in glycosylation of AGP are associated with cancer progression. However, changes in AGP levels of serum and changes in glycosylation of AGPs in breast cancer have not been specifically studied. In the present study, serum AGP levels in benign (BN) cancer and breast cancer stage I (BC I), BC IIA, BC IIB, and BC III in Korean women were measured using an enzyme-linked immunosorbent assay (ELISA). AGP was purified from individual sera by hot phenol extraction and then subjected to AGP glycosylation analysis. Three types of AGP glycosylation (fucosylation, high-mannose-type and sialylation) were detected using enzyme-linked lectin assays (ELLAs). Serum AGP levels were higher in BC I, BC IIA, BC IIB, and BC III, than in the BN group, and the level in BC I and BC IIA was high enough to be distinguished from BN. Meanwhile, terminal fucosylation and high-mannose-type glycans appeared to be lowest in BC I. The glycosylation levels of BC I provide sensitivity and specificity that make BC I clearly distinguishable from BC IIA, BC IIB, and BC III as well as BN. Therefore, determination of serum AGP or AGP glycosylation level could be useful for detecting the early stages of breast cancer.

Urine α-fetoprotein and orosomucoid 1 as biomarkers of hepatitis B virus-associated hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the sixth common malignant tumor worldwide, but current efficient and convenient screening methods remain lacking. This study aimed to discover a diagnostic or a screening biomarker from the urine of hepatitis B virus (HBV)-related HCC patients. We used iTRAQ coupled with mass spectrometry to identify candidate urinary proteins in a discovery cohort (n = 40). The selected proteins were confirmed using ELISA in a validation cohort (n = 140). Diagnostic performance of the selected proteins was assessed using receiver operating characteristic (ROC) and qualitative diagnostic analysis. A total of 96 differentially expressed proteins were identified. Urinary α-fetoprotein (u-AFP) and orosomucoid 1 (u-ORM1) were selected as target proteins by bioinformatics analysis and were significantly higher in HCC than in non-HCC patients, as validated by Western blot analysis and ELISA. u-AFP had a strong correlation with serum AFP-L3 (Pearson's r = 0.944, P < 0.0001), indicating that u-AFP may be derived from circulating blood. The area under the curve (AUC) of u-AFP was 0.795 with a sensitivity of 62.5% and a specificity of 95.4%, which showed no significantly difference with serum AFP (se-AFP). The AUC was 0.864 as u-AFP and u-ORM1 were combined, and they performed much better than u-AFP or u-ORM1 alone. Qualitative diagnostic analysis showed that the positive predictive value of u-AFP was 90.1% and the diagnostic sensitivity of parallel combination of u-AFP and u-ORM1 was 85.1%. Taken together, AFP and ORM1 in the urine may be used as a diagnostic or screening biomarker of HCC, and studies on large samples are needed to validate the result.NEW & NOTEWORTHY This study provides a novel way to find biomarkers of hepatocellular carcinoma (HCC) and a new perspective of α-fetoprotein clinical application. The urine reagent strips may be helpful in high epidemic areas of HCC and in low-resource settings.

Quantification of the α2-6 Sialic Acid Linkage in Branched N-Glycan Structures with Capillary Nanogel Electrophoresis

Sialylation and sialic acid linkage in N-glycans are markers of disease but are analytically challenging to quantify. A capillary electrophoresis method is reported that integrates a unique combination of enzymes and lectins to modify sialylated N-glycans in real time in the capillary so that N-glycan structures containing α2-6-linked sialic acid are easily separated, detected, and quantified. In this study, N-glycans were sequentially cleaved by enzymes at the head of the separation capillary so that the presence of α2-6-linked sialic acids corresponded to a shift in the analyte migration time in a manner that enabled interpretation of the N-glycan structure. Following injection, only afucosylated N-glycan structures were passed through enzyme zones that contained α2-3 sialidase, followed by β1-3,4 galactosidase, which cleaved any terminal α2-3-linked sialic acid and underlying galactose yielding a terminal N-acetyl glucosamine. With this treatment complete, a third zone of α2-3,6,8 sialidase converted the remaining α2-6-linked sialic acid to terminal galactose. With these enzyme processing steps the α2-6-linked sialic acid residues on an N-glycan correlated directly to the number of terminal galactose residues that remained. The number of terminal galactose residues could be interpreted as a stepwise decrease in the migration time. Complex N-glycans from α-1-acid glycoprotein were analyzed using this approach, revealing that a limited number of α2-6-linked sialic acids were present with biantennary, triantennary, and tetraantennary N-glycans of α-1-acid glycoprotein generally containing 0 or 1 α2-6-linked sialic acid.

Aberrant glycosylation and cancer biomarker discovery: a promising and thorny journey

Glycosylation is among the most important post-translational modifications for proteins and is of intrinsic complex character compared with DNAs and naked proteins. Indeed, over 50%-70% of proteins in circulation are glycosylated, and the "sweet attachments" have versatile structural and functional implications. Both the configuration and composition of the attached glycans affect the biological activities of consensus proteins significantly. Glycosylation is generated by complex biosynthetic pathways comprising hundreds of glycosyltransferases, glycosidases, transcriptional factors, transporters and the protein backbone. In addition, lack of direct genetic templates and glyco-specific antibodies such as those commonly used in DNA amplification and protein capture makes research on glycans and glycoproteins even more difficult, thus resulting in sparse knowledge on the pathophysiological implications of glycosylation. Fortunately, cutting-edge technologies have afforded new opportunities and approaches for investigating cancer-related glycosylation. Thus, glycans as well as aberrantly glycosylated protein-based cancer biomarkers have been increasingly recognized. This mini-review highlights the most recent developments in glyco-biomarker studies in an effort to discover clinically relevant cancer biomarkers using advanced analytical methodologies such as mass spectrometry, high-performance liquid chromatographic/ultra-performance liquid chromatography, capillary electrophoresis, and lectin-based technologies. Recent clinical-centered glycobiological studies focused on determining the regulatory mechanisms and the relation with diagnostics, prognostics and even therapeutics are also summarized. These studies indicate that glycomics is a treasure waiting to be mined where the growth of cancer-related glycomics and glycoproteomics is the next great challenge after genomics and proteomics.

Dramatically changed immune-related molecules as early diagnostic biomarkers of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the main type of lung cancer, with a low 5-year survival rate because of the absence of effective clinical biomarkers for early diagnosis. Based on the immunosurveillance theory, we proposed that changes in the immune system are more pronounced than tumour-associated antigens during the early stage of cancer. Therefore, a new strategy was designed to screen early diagnostic biomarkers from peripheral leukocytes in early-stage NSCLCs with transcriptome sequencing. A total of 358 immune-related differentially expressed genes were identified between early-NSCLC patients and healthy individuals. Orosomucoid-1 (ORM1, a acute phase protein), the total ORM and chitotriosidase-1 (involved in degradation of chitobiose) were selected for further verification in 210 serum samples by western blotting, ELISA and nephelometry immunoassay (based on immuno-scatter turbidmetry). Receiver operating characteristic curve analysis show that ORM1 and total ORM have excellent diagnostic efficacies, with area under the curve of 0.862 and 0.920, respectively, which significantly distinguished very early-NSCLC (IA) from healthy samples. Flow cytometry results showed that CD15⁺ neutrophils made up 73% of ORM1⁺ peripheral leukocytes. In mouse lung cancer model, serum ORM1, but not liver ORM1, changed significantly in the early stage of NSCLC. ORM1 expression in peripheral leukocytes was regulated by TGF-β and mediated by the TGF-β/Smad signalling pathway. Our results indicated that combined ORM and TGF-β could be a promising clinical biomarker in the diagnosis of early NSCLC.

Evaluation of AGP Fucosylation as a Marker for Hepatocellular Carcinoma of Three Different Etiologies

A mass spectrometric analysis platform has been developed to determine whether glycosylation patterns of alpha-1 acid glycoprotein (AGP) could be used as a marker for early detection of hepatocellular carcinoma (HCC) in different etiologies, i.e. non-alcoholic steatohepatitis (NASH), alcoholic liver disease (ALC), and hepatitis C virus (HCV). MALDI-MS profiling of N-glycans of AGP purified from 20 μL of patient serum in HCC (n = 72) and liver cirrhosis (n = 58) showed that a unique trifucosylated tetra-antennary glycan (m/z 3490.76) was predominantly identified in HCCs but was absent in healthy subjects and the majority of cirrhosis patients. Receiver operation characteristic (ROC) curve analysis showed that the trifucosylated N-glycan of AGP (triFc_AGP) could differentiate HCC from cirrhosis with an area under the curve (AUC) of 0.707, 0.726 and 0.751 for NASH, ALC and HCV, respectively. When combining triFc_AGP with INR and AFP, the panel had the greatest benefit in detection of NASH-related HCCs, with a significantly improved AUC of 0.882 for all NASH HCCs and 0.818 for early NASH HCCs compared to AFP alone (0.761 and 0.641, respectively). Moreover, triFc_AGP could serve as a potential marker for monitoring AFP-negative HCC patients.

Development and evaluation of silica-based lectin microcolumns for glycoform analysis of alpha1-acid glycoprotein

Silica-based lectin microcolumns were developed and optimized for the separation and analysis of glycoform fractions in alpha₁-acid glycoprotein (AGP) based on both the degree of branching and level of fucosylation. Concanavalin A (Con A) and Aleuria Aurantia lectin (AAL) were immobilized onto HPLC-grade silica by reductive amination and packed into 2.1 mm i.d. × 5.0 cm microcolumns. Factors examined for these microcolumns include their protein content, binding capacity, binding strength and band-broadening under isocratic conditions (Con A) or step elution conditions (AAL) and in the presence of various flow rates or temperatures. These factors were examined by using experiments based on frontal analysis, zonal elution, peak profiling and peak decay analysis. Up to 200 μg AGP could be loaded onto a Con A microcolumn and provide linear elution conditions, and 100 μg AGP could be applied to an AAL microcolumn. The final conditions for separating retained and non-retained AGP glycoform fractions on a Con A microcolumn used a flow rate of 50 μL min^-1 and a temperature of 50 °C, which gave a separation of these fractions within 20 min or less. The final conditions for an AAL microcolumn included a flow rate of 0.75 mL min^-1, a temperature of 50 °C, and the use of 2.0 mM l-fucose as a competing agent for elution, giving a separation of non-retained and retained AGP glycoforms in 6 min or less. The inter-day precisions were ±0.7-4.0% or less for the retention times of the AGP glycoforms and ±2.2-3.0% or less for their peak areas.

Fucosylation in cancer biology and its clinical applications

Fucosylation is the process of transferring fucose from GDP-fucose to their substrates, which includes certain proteins, N- and O-linked glycans in glycoprotein or glycolipids, by fucosyltransferases in all mammalian cells. Fucosylated glycans play vital role in selectin-mediated leukocyte extravasation, lymphocyte homing, and pathogen-host interactions, whereas fucosylated proteins are essential for signaling transduction in numerous ontogenic events. Aberrant fucosylation due to the availability of high energy donor GDP-fucose, abnormal expression of FUTs and/or α-fucosidase, and the availability of their substrates leads to different fucosylated glycan or protein structures. Accumulating evidence demonstrates that aberrant fucosylation plays important role in all aspects of cancer biology. In this review, we will summarize the current knowledge about fucosylation in different physiological and pathological processes with a focus on their roles not only in cancer cell proliferation, invasion, and metastasis but also in tumor immune surveillance. Furthermore, the clinical potential and applications of fucosylation in cancer diagnosis and treatment will also be discussed.

Fast and facile analysis of glycosylation and phosphorylation of fibrinogen from human plasma-correlation with liver cancer and liver cirrhosis

Hepatocellular carcinoma (HCC) is one of the deadliest cancers due to its late diagnosis with the main risk factor being liver cirrhosis (LC). Glycan structures from glycoproteins are usually altered in cancer. Blood plasma from 111 healthy and sick donors was analyzed to determine the post-translational modifications (PTM) of intact Aα-, Bβ-, and γ-subunits of fibrinogen, a glycoprotein predominantly produced in liver cells. Glycosylation and phosphorylation of the protein species were quantified by liquid chromatography coupled to mass spectrometry to correlate PTMs to pathological cases. Quantities of the PTMs were used for statistical classification by principal component analysis (PCA) and multivariate analysis of variance (MANOVA). As relevant clinical finding, patients with liver disease (HCC and/or LC) were distinguished from individuals without relevant chronic liver disease with 91% sensitivity and 100% specificity. Within the group of patients with liver disease, a robust separation between LC and HCC was not possible. In more detail, the phosphorylation of Aα-subunit is decreased in HCC patients, whereas the monophosphorylated state is significantly increased in LC patients. In terms of glycosylation, the amount of O-glycans in the Aα-subunit is decreased in LC patients, while sialylation and fucosylation of N-type glycans of Bβ- and γ-subunits are increased in LC and HCC. Based on PTM of fibrinogen, starting from plasma we can assign the status of an individual as healthy or as liver disease in less than 3 h.