Progress in research into the role of abnormal glycosylation modification in tumor immunity

A Fully Automated Online Enrichment and Separation System for Highly Reproducible and In-Depth Analysis of Intact Glycopeptide

A fully automated online enrichment and separation system for intact glycopeptides, named AutoGP, was developed in this study by integrating three different columns in a nano-LC system. Specifically, the peptide mixture from the enzymatic digestion of a complex biological sample was first loaded on a hydrophilic interaction chromatography (HILIC) column. The nonglycopeptides in the sample were washed off the column, and the glycopeptides retained by the HILIC column were eluted to a C18 trap column to achieve an automated glycopeptide enrichment. The enriched glycopeptides were further eluted to a C18 column for separation, and the separated glycopeptides were eventually analyzed by using an orbitrap mass spectrometer (MS). The optimal operating conditions for AutoGP were systemically studied, and the performance of the fully optimized AutoGP was compared with a conventional manual system used for glycopeptide analysis. The experimental evaluation shows that the total number of glycopeptides identified is at least 1.5-fold higher, and the median coefficient of variation for the analyses is at least 50% lower by using AutoGP, as compared to the results acquired by using the manual system. In addition, AutoGP can perform effective analysis even with a 1-μg sample amount, while a 10-μg sample at least will be needed by the manual system, implying an order of magnitude better sensitivity of AutoGP. All the experimental results have consistently proven that AutoGP can be used for much better characterization of intact glycopeptides.

Construction of an abnormal glycosylation risk model and its application in predicting the prognosis of patients with head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is the most common malignant tumor of the head and neck, and the incidence rate is increasing year by year. Protein post-translational modification, recognized as a pivotal and extensive form of protein modification, has been established to possess a profound association with tumor occurrence and progression. This study employed bioinformatics analysis utilizing transcriptome sequencing data, patient survival data, and clinical data from HNSCC to establish predictive markers of genes associated with glycosylation as prognostic risk markers. The R procedure WGCNA was employed to construct a gene co-expression network using the gene expression profile and clinical characteristics of HNSCC samples. Multiple Cox Proportional Hazards Regression Model (Cox regression) and LASSO analysis were conducted to identify the key genes exhibiting the strongest association with prognosis. A risk score, known as the glycosylation-related genes risk score (GLRS), was subsequently formulated utilizing the aforementioned core genes. This scoring system facilitated the classification of samples into high-risk and low-risk categories, thereby enabling the prediction of patient prognosis. The association between GLRS and clinical variables was examined through both univariate and multivariate Cox regression analysis. The validation of six core genes was accomplished using quantitative real-time polymerase chain reaction (qRT-PCR). The findings demonstrated noteworthy variations in risk scores among subgroups, thereby affirming the efficacy of GLRS in prognosticating patient outcomes. Furthermore, a correlation has been observed between the risk-scoring model and immune infiltration. Moreover, significant disparities exist in the expression levels of diverse immune checkpoints, epithelial-mesenchymal transition genes, and angiogenic factors between the high and low-risk groups.

FUT6 inhibits the proliferation, migration, invasion, and EGF-induced EMT of head and neck squamous cell carcinoma (HNSCC) by regulating EGFR/ERK/STAT signaling pathway

Glycosylation change is one of the landmark events of tumor occurrence and development, and tumor cells may be inhibited by regulating the aberrant expression of glycosyltransferases. Currently, fucosyltransferase VI (FUT6), which is involved in the synthesis of α-1, 3 fucosyl bond, has been detected to be closely associated with multiple tumors, but its function and mechanism in head and neck squamous cell carcinoma (HNSCC) still need further research. In this study, FUT6 knockdown and overexpression strategies were used to investigate the effects of FUT6 on cell proliferation, migration, and invasion, as well as the growth and metastasis of HNSCC in a xenografts mouse model. The protein expression levels of epidermal growth factor receptor (EGFR), extracellular signal-regulated kinase (ERK), Signal Transducer and Activator of Transcription (STAT), protein kinase B (AKT), c-Myc, and epithelial-mesenchymal transition (EMT) markers were determined by western blot analysis. Our research found that the mRNA expression of FUT6 was lower in HNSCC tissues than in normal mucosal epithelial tissues. In Cal-27 and FaDu cells, FUT6 overexpression inhibited cell proliferation, migration and invasion, causing upregulation of ZO-1 and E-cadherin, downregulation of N-cadherin and Vimentin, and finally decreased the phosphorylation levels of EGFR, ERK, STAT, and c-Myc. In HSC-3 cells, knockdown of FUT6 promoted cell proliferation, migration and invasion, downregulating ZO-1 and E-cadherin, upregulating N-cadherin and Vimentin, and increased the phosphorylation levels of EGFR, ERK, STAT, and c-Myc. In the HNSCC xenografts mouse, FUT6 overexpression inhibited tumor growth and metastasis. In summary, FUT6 controls the proliferation, migration, invasion, and EGF-induced EMT of HNSCC by regulating EGFR/ERK/STAT signaling pathway, indicating its potential future therapeutic application for HNSCC.

Glutamine promotes O-GlcNAcylation of G6PD and inhibits AGR2 S-glutathionylation to maintain the intestinal mucus barrier in burned septic mice

Mucus forms the first line of defence of the intestinal mucosa barrier, and mucin is its core component. Glutamine is a vital energy substance for goblet cells; it can promote mucus synthesis and alleviate damage to the intestinal mucus barrier after burn injury, but its mechanism is not fully understood. This study focused on the molecular mechanisms underlying the effects of glutamine on the synthesis and modification of mucin 2 (MUC2) by using animal and cellular models of burn sepsis. We found that anterior gradient-2 (AGR2) plays a key role in the posttranslational modification of MUC2. Oxidative stress induced by burn sepsis enhanced the S-glutathionylation of AGR2, interfered with the processing and modification of MUC2 precursors by AGR2 and blocked the synthesis of mature MUC2. Further studies revealed that NADPH, catalysed by glucose-6-phosphate dehydrogenase (G6PD), is a key molecule in inhibiting oxidative stress and regulating AGR2 activity. Glutamine promotes O-linked N-acetylglucosamine (O-GlcNAc) modification of G6PD via the hexosamine pathway, which facilitates G6PD homodimer formation and increases NADPH synthesis, thereby inhibiting AGR2 S-glutathionylation and promoting MUC2 maturation, ultimately reducing damage to the intestinal mucus barrier after burn sepsis. Overall, we have demonstrated that the central mechanisms of glutamine in promoting MUC2 maturation and maintaining the intestinal mucus barrier are the enhancement of G6PD glycosylation and inhibition of AGR2 S-glutathionylation.

Glycoproteomic analysis reveals the effects of bisecting GlcNAc in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is the second major subtype of primary liver cancer and has caused more and more attention with increasing incidence and mortality worldwide. Our previous study found that bisecting N-glycans are commonly increased in ICC, while the effects and potential functions of bisecting GlcNAc in ICC are still largely unclear. In this study, we further confirmed that the structures of bisecting GlcNAc were significantly up-regulated in ICC compared with paracancer tissues by glycoproteomic data and lectin histochemistry. The expression of its glycosyltransferase MGAT3 was also up-regulated in ICC tissues at both mRNA and protein levels, and expression of MGAT3 is negatively correlated with overall survival explored by bioinformatic analyses and published datasets from 255 patients. Next, the silencing of MGAT3 could inhibit the growth and invasion of ICC cells, and overexpressing of MGAT3 only promoted ICC cell invasion. Further glycoproteomic analysis showed that the commonly glycoproteins modified by bisecting GlcNAc after MGAT3-overexpression in two ICC cell lines were mainly involved in cell movement-related biological processes, such as cell adhesion, integrin-related and ECM-receptor interaction. This study sheds light on the potential effects of bisecting GlcNAc in ICC cells and suggests that MGAT3 might be used as a potential target in the therapy of ICC.

Characterization of glycosylation regulator-mediated glycosylation modification patterns and tumor microenvironment infiltration in hepatocellular carcinoma

Background: Previous studies have shown that glycosylation of proteins ofen plays an important role in HCC. However, the potential mechanism of glycosylation in HCC has not been described systematically. Methods: We comprehensively evaluated the glycosylation patterns in HCC samples based on 43 glycosylation regulators, and annotated the modification patterns with the enrichment of immune cells and stromal cells. Considering the heterogeneity of HCC patients, the glycosylation score was constructed using single-sample gene set enrichment analysis (ssGSEA). We also explored the drugs that different HCC patients were sensitive to based on glycosylation mode and score. Results: We identified three glycosylation-regulated gene subtypes. By annotating the subtypes, it was found that the glycosylation regulated gene subtypes was highly matched with three immunophenotypes of HCC (immune-inflamed, immune-excluded, and immune-desert), regardless of the characteristics of immune cell infiltration or prognosis. Based on the characteristic genes of glycosylation-regulated gene subtypes, we constructed a glycosylation-related model, and found that glycosylation-related model was highly consistent with the glycosylation regulated gene subtypes. The glycosylation score that evaluates the glycosylation characteristics of a single HCC sample has high prognostic value, and the prognosis of patients with high glycosylation score is significantly worse. Interestingly, we found that the glycosylation score was closely related to tumor node metastasis (TNM) staging. By applying glycosylation-regulated gene subtypes and glycosylation score to explore the sensitivity of different patients to anticancer drugs, it was found that the sensitivity of Thapsigargin, Shikonin, Embelin and Epothilone. B was closely related to the glycosylation mode. Conclusion: This study reveals that the diversity of glycosylation patterns plays an important role in HCC. Therefore, evaluating the glycosylation patterns of patients with HCC will be helpful in identifying the characteristics of immune cell infiltration and selecting accurate treatment methods.

Three Major Gastrointestinal Cancers Could Be Distinguished through Subclass-Specific IgG Glycosylation

Esophageal cancer (EC), gastric cancer (GC), and colorectal cancer (CRC) are three major digestive tract tumors with higher morbidity and mortality due to significant molecular heterogeneity. Altered IgG glycosylation has been observed in inflammatory activities and disease progression, and the IgG glycome profile could be used for disease stratification. However, IgG N-glycome profiles in these three cancers have not been systematically investigated. Herein, subclass-specific IgG glycosylation in CRC, GC, and EC was comprehensively characterized by liquid chromatography-tandem mass spectrometry. It was found that IgG1 sialylation was decreased in all three cancers, and the alterations in CRC and EC may be subclass-specific. IgG4 mono-galactosylation was increased in all three cancers, which was a subclass-specific change in all of them. Additionally, glycopeptides of IgG1-H5N5, IgG2-H4N3F1, and IgG4-H4N4F1 could distinguish all three cancer groups from controls with fair diagnostic performance. Furthermore, bioinformatics verified the differential expression of relevant glycosyltransferase genes in cancer progression. Significantly, those three gastrointestinal cancers could be distinguished from each other using subclass-specific IgG glycans. These findings demonstrated the spatial and temporal diversity of IgG N-glycome among digestive cancers, increasing our understanding of the molecular mechanisms of EC, GC, and CRC pathogenesis.

p-Coumaric acid, Kaempferol, Astragalin and Tiliroside Influence the Expression of Glycoforms in AGS Gastric Cancer Cells

Abnormal glycosylation of cancer cells is considered a key factor of carcinogenesis related to growth, proliferation, migration and invasion of tumor cells. Many plant-based polyphenolic compounds reveal potential anti-cancer properties effecting cellular signaling systems. Herein, we assessed the effects of phenolic acid, p-coumaric acid and flavonoids such as kaempferol, astragalin or tiliroside on expression of selected cancer-related glycoforms and enzymes involved in their formation in AGS gastric cancer cells. The cells were treated with 80 and 160 µM of the compounds. RT-PCR, Western blotting and ELISA tests were performed to determine the influence of polyphenolics on analyzed factors. All the examined compounds inhibited the expression of MUC1, ST6GalNAcT2 and FUT4 mRNAs. C1GalT1, St3Gal-IV and FUT4 proteins as well as MUC1 domain, Tn and sialyl T antigen detected in cell lysates were also lowered. Both concentrations of kaempferol, astragalin and tiliroside also suppressed ppGalNAcT2 and C1GalT1 mRNAs. MUC1 cytoplasmic domain, sialyl Tn, T antigens in cell lysates and sialyl T in culture medium were inhibited only by kaempferol and tiliroside. Nuclear factor NF-κB mRNA expression decreased after treatment with both concentrations of kaempferol, astragalin and tiliroside. NF-κB protein expression was inhibited by kaempferol and tiliroside. The results indicate the rationality of application of examined polyphenolics as potential preventive agents against gastric cancer development.

Comprehensive Analysis of the Potential Prognostic Value of 11 Glycosylation-Related Genes in Head and Neck Squamous Cell Carcinoma and Their Correlation with PD-L1 Expression and Immune Infiltration

Background

Head and neck squamous cell carcinoma (HNSCC) is one of the worst and most common malignant tumors. This study is aimed at studying the complex interaction between glycosylation-related genes and HNSCC.

Methods

The Cancer Genome Atlas (TCGA) contains gene expression profile data of HNSCC and normal tissues, as well as patient survival and clinical data. Combining five glycosylation-related gene sets, bioinformatics was used to analyze the expression of glycosylation-related genes in TCGA-HNSCC datasets and to identify prognostic risk markers, analyze their prognostic value, and the influence of glycosylation-related genes on the tumor immune microenvironment.

Results

Gene expression profiles and corresponding clinical information of 499 cases of HNSCC and 44 cases of adjacent tissues were obtained. Using 11 glycosylation-related genes to construct a prognostic risk score, the Kaplan-Meier curve analysis found that the overall survival of the high-risk group was significantly different than that of the low-risk group (P < 0.001). ROC analysis was used to evaluate the prognostic efficacy of prognostic risk markers, and the results showed that the prognostic risk markers had good efficacy in predicting the prognosis of patients. We also found that there is a correlation between glycosylation-related genes, PD-L1, and immunocyte infiltration, and there is a dynamic effect between the change in the copy number of glycosylation-related genes and the number of tumor-infiltrating immune cells.

Conclusions

Our research shows that glycosylation-related prognostic risk markers may be independent risk factors for the prognosis of HNSCC. We have found that there may be subtle links between glycosylation-related genes, PD-L1, and immunocyte infiltration, which has certain significance for exploring the occurrence and development of HNSCC and exploring the research of targeted therapy.

Autophagic tumor-associated macrophages promote the endothelial mesenchymal transition in lung adenocarcinomas through the FUT4/p-ezrin pathway

Background

Lung adenocarcinoma is one of the most common malignant tumors with high morbidity and mortality, but the effect of Tumor-associated macrophages (TAMs) on lung adenocarcinoma has not been studied clearly now.

Methods

In this study, TAMs were stably transfected with Atg5 silence or overexpression lentiviral vectors to inhibit or induce autophagy of TAMs. In addition, the expression of fucosyltransferase IV (FUT4) or Ezrin were interfered in TAMs with autophagy. The above treated TAMs were then co-cultured with A549 or H1299 cells. The expressions of genes were detected by qPCR, western blotting, cell immunofluorescence, and enzyme-linked immunosorbent assay. Meanwhile, cell migration and invasion were analyzed by Transwell assay and wound healing assay. Furthermore, the effects of TAMs with autophagy were explored in lung adenocarcinoma xenograft model of mice.

Results

The results showed that overexpression of autophagy-related gene 5 (ATG5) induced autophagy in TAMs, which increased the expression of FUT4, TGF-β1, and p-ezrin, and promoted epithelial-mesenchymal transition (EMT) in lung adenocarcinoma cells. However, FUT4 silencing partially reversed the effects of TAM autophagy, specifically, the expression of TGF-β1 and p-ezrin was inhibited and EMT in lung adenocarcinoma cells was suppressed. Notably, ezrin deletion in autophagic TAMs induced by rapamycin reduced TGF-β1 expression and suppressed EMT in lung adenocarcinoma cells. Consistently, in vivo experiments also revealed that autophagic TAMs increased the expression of FUT4, TGF-β1, and p-ezrin, and promoted EMT in lung adenocarcinomas. Similarly, FUT4 silencing partially reversed the effects of autophagic TAMs on EMT in lung adenocarcinomas.

Conclusions

In conclusion, autophagic TAMs promoted TGF-β1 secretion through the FUT4/p-ezrin pathway and induced EMT in co-cultured lung adenocarcinoma cells.

Targeting the "Sweet Side" of Tumor with Glycan-Binding Molecules Conjugated-Nanoparticles: Implications in Cancer Therapy and Diagnosis

Nanotechnology is in the spotlight of therapeutic innovation, with numerous advantages for tumor visualization and eradication. The end goal of the therapeutic use of nanoparticles, however, remains distant due to the limitations of nanoparticles to target cancer tissue. The functionalization of nanosystem surfaces with biological ligands is a major strategy for directing the actions of nanomaterials specifically to tumor cells. Cancer formation and metastasis are accompanied by profound alterations in protein glycosylation. Hence, the detection and targeting of aberrant glycans are of great value in cancer diagnosis and therapy. In this review, we provide a brief update on recent progress targeting aberrant glycosylation by functionalizing nanoparticles with glycan-binding molecules (with a special focus on lectins and anti-glycan antibodies) to improve the efficacy of nanoparticles in cancer targeting, diagnosis, and therapy and outline the challenges and limitations in implementing this approach. We envision that the combination of nanotechnological strategies and cancer-associated glycan targeting could remodel the field of cancer diagnosis and therapy, including immunotherapy.