Tumor-associated carbohydrate antigens defining tumor malignancy: basis for development of anti-cancer vaccines

Photothermal therapy with immune-adjuvant nanoparticles together with checkpoint blockade for effective cancer immunotherapy

A therapeutic strategy that can eliminate primary tumours, inhibit metastases, and prevent tumour relapses is developed herein by combining adjuvant nanoparticle-based photothermal therapy with checkpoint-blockade immunotherapy. Indocyanine green (ICG), a photothermal agent, and imiquimod (R837), a Toll-like-receptor-7 agonist, are co-encapsulated by poly(lactic-co-glycolic) acid (PLGA). The formed PLGA-ICG-R837 nanoparticles composed purely by three clinically approved components can be used for near-infrared laser-triggered photothermal ablation of primary tumours, generating tumour-associated antigens, which in the presence of R837-containing nanoparticles as the adjuvant can show vaccine-like functions. In combination with the checkpoint-blockade using anti-cytotoxic T-lymphocyte antigen-4 (CTLA4), the generated immunological responses will be able to attack remaining tumour cells in mice, useful in metastasis inhibition, and may potentially be applicable for various types of tumour models. Furthermore, such strategy offers a strong immunological memory effect, which can provide protection against tumour rechallenging post elimination of their initial tumours.

Photothermal therapy can induce an anti-tumour immune response by producing tumour-associated antigens. Here, the authors design a nanoparticle that simultaneously acts as a photothermal agent and an immune-adjuvant and demonstrate the anti-tumour efficacy in combination with anti-CTLA4 therapy in preclinical murine cancer models.

A systematic framework to derive N-glycan biosynthesis process and the automated construction of glycosylation networks

Background

Abnormalities in glycan biosynthesis have been conclusively related to various diseases, whereas the complexity of the glycosylation process has impeded the quantitative analysis of biochemical experimental data for the identification of glycoforms contributing to disease. To overcome this limitation, the automatic construction of glycosylation reaction networks in silico is a critical step.

Results

In this paper, a framework K2014 is developed to automatically construct N-glycosylation networks in MATLAB with the involvement of the 27 most-known enzyme reaction rules of 22 enzymes, as an extension of previous model KB2005. A toolbox named Glycosylation Network Analysis Toolbox (GNAT) is applied to define network properties systematically, including linkages, stereochemical specificity and reaction conditions of enzymes. Our network shows a strong ability to predict a wider range of glycans produced by the enzymes encountered in the Golgi Apparatus in human cell expression systems.

Conclusions

Our results demonstrate a better understanding of the underlying glycosylation process and the potential of systems glycobiology tools for analyzing conventional biochemical or mass spectrometry-based experimental data quantitatively in a more realistic and practical way.

Temporal relationship between cancer and myositis identifies two distinctive subgroups of cancers: impact on cancer risk and survival in patients with myositis

OBJECTIVES

The aim was to compare standardized incidence ratios (SIRs) of cancers temporally related and unrelated to active myositis in patients with myositis.

METHODS

Fifty-two cancer cases were identified in 281 myositis patients. SIRs of cancers having temporal overlap with the active phase of myositis [cancers concurrent with active myositis (CAM), n = 30] and cancers not having such temporal overlap [cancers non-concurrent with active myositis (CNM), n = 22] were compared in 281 patients.

RESULTS

Patients with CAM were older at diagnosis of myositis, had a greater tendency to be male, more frequent dysphagia and less frequent interstitial lung disease than patients with CNM. CAM SIR (95% CI) was 1.78 (1.19, 2.56) and CNM SIR 1.23 (0.75, 1.90). The peak SIR was observed in the seventh decade of life for CAM and in the third decade for CNM. When stratified by myositis-cancer intervals, CAM SIR was 9.94 (6.43, 14.67) within 1 year of myositis diagnosis, whereas no temporal relationship was found for CNM. Elevated SIRs were observed for oesophageal cancer [57.77 (11.91, 168.82)], non-Hodgkin's lymphoma [41.43 (13.45, 96.69)], adenocarcinoma of unknown primary origin [67.6 (18.42, 173.07]), lung cancer [7.27 (1.98, 18.61)] and ovarian cancer [19.15 (2.32, 69.17)] within 3 years of CAM diagnosis. The cancer stage at the time of diagnosis was more advanced in CAM than CNM (P < 0.001), with a correspondingly increased hazard ratio of mortality [4.3 (1.5, 12.7)] in patients with CAM vs CNM.

CONCLUSION

A significantly elevated SIR was found for CAM, whereas there was a comparable SIR for CNM relative to the general population. Multiple types of cancers showed elevated SIRs among CAM, but none among CNM. Given that cancer stages in CAM were far advanced at diagnosis, mortality risk was greater in patients with CAM.

Cancer Vaccines in Ovarian Cancer: How Can We Improve?

Epithelial ovarian cancer (EOC) is one important cause of gynecologic cancer-related death. Currently, the mainstay of ovarian cancer treatment consists of cytoreductive surgery and platinum-based chemotherapy (introduced 30 years ago) but, as the disease is usually diagnosed at an advanced stage, its prognosis remains very poor. Clearly, there is a critical need for new treatment options, and immunotherapy is one attractive alternative. Prophylactic vaccines for prevention of infectious diseases have led to major achievements, yet therapeutic cancer vaccines have shown consistently low efficacy in the past. However, as they are associated with minimal side effects or invasive procedures, efforts directed to improve their efficacy are being deployed, with Dendritic Cell (DC) vaccination strategies standing as one of the more promising options. On the other hand, recent advances in our understanding of immunological mechanisms have led to the development of successful strategies for the treatment of different cancers, such as immune checkpoint blockade strategies. Combining these strategies with DC vaccination approaches and introducing novel combinatorial designs must also be considered and evaluated. In this review, we will analyze past vaccination methods used in ovarian cancer, and we will provide different suggestions aiming to improve their efficacy in future trials.

Relationship between ST8SIA2, polysialic acid and its binding molecules, and psychiatric disorders

Polysialic acid (polySia, PSA) is a unique and functionally important glycan, particularly in vertebrate brains. It is involved in higher brain functions such as learning, memory, and social behaviors. Recently, an association between several genetic variations and single nucleotide polymorphisms (SNPs) of ST8SIA2/STX, one of two polysialyltransferase genes in vertebrates, and psychiatric disorders, such as schizophrenia (SZ), bipolar disorder (BD), and autism spectrum disorder (ASD), was reported based on candidate gene approaches and genome-wide studies among normal and mental disorder patients. It is of critical importance to determine if the reported mutations and SNPs in ST8SIA2 lead to impairments of the structure and function of polySia, which is the final product of ST8SIA2. To date, however, only a few such forward-directed studies have been conducted. In addition, the molecular mechanisms underlying polySia-involved brain functions remain unknown, although polySia was shown to have an anti-adhesive effect. In this report, we review the relationships between psychiatric disorders and polySia and/or ST8SIA2, and describe a new function of polySia as a regulator of neurologically active molecules, such as brain-derived neurotrophic factor (BDNF) and dopamine, which are deeply involved in psychiatric disorders. This article is part of a Special Issue entitled "Glycans in personalised medicine" Guest Editor: Professor Gordan Lauc.

Dinutuximab for the treatment of pediatric patients with high-risk neuroblastoma

Neuroblastoma (NB) is the most common extra cranial solid tumor of childhood, with 60% of patients presenting with high risk (HR) NB by means of clinical, pathological and biological features. The 5-year survival rate for HR-NB remains below 40%, with the majority of patients suffering relapse from chemorefractory tumor. Immunotherapy is the main strategy against minimal residual disease and clinical experience has mostly focused on monoclonal antibodies (MoAb) against the glycolipid disialoganglioside GD2. Three anti-GD2 antibodies have been tested in the clinic including murine 14G2a, human-mouse chimeric ch14.18 and 3F8. Anti-GD2 MoAb induces cellular cytoxicity against NB and is most effective when effector cells like natural killer cells, granulocytes and macrophages are amplified by cytokines. The combination of cytokines IL-2 and GM-CSF with the anti-GD2 MoAb ch14.18 (Dinutuximab) has shown a significant improvement in outcome for HR-NB. The FDA and EMA approved dinutuximab (Unituxin(R)) in 2015 for the treatment of patients with HR-NB who achieved at least a partial response after multimodality therapy.

Clinically feasible approaches to potentiating cancer cell-based immunotherapies

The immune system exerts both tumor-destructive and tumor-protective functions. Mature dendritic cells (DCs), classically activated macrophages (M1), granulocytes, B lymphocytes, aβ and ɣδ T lymphocytes, natural killer T (NKT) cells, and natural killer (NK) cells may be implicated in antitumor immunoprotection. Conversely, tolerogenic DCs, alternatively activated macrophages (M2), myeloid-derived suppressor cells (MDSCs), and regulatory T (Tregs) and B cells (Bregs) are capable of suppressing antitumor immune responses. Anti-cancer vaccination is a useful strategy to elicit antitumor immune responses, while overcoming immunosuppressive mechanisms. Whole tumor cells or lysates derived thereof hold more promise as cancer vaccines than individual tumor-associated antigens (TAAs), because vaccinal cells can elicit immune responses to multiple TAAs. Cancer cell-based vaccines can be autologous, allogeneic or xenogeneic. Clinical use of xenogeneic vaccines is advantageous in that they can be most effective in breaking the preexisting immune tolerance to TAAs. To potentiate immunotherapy, vaccinations can be combined with other modalities that target different immune pathways. These modalities include 1) genetic or chemical modification of cell-based vaccines; 2) cross-priming TAAs to T cells by engaging dendritic cells; 3) T-cell adoptive therapy; 4) stimulation of cytotoxic inflammation by non-specific immunomodulators, toll-like receptor (TLR) agonists, cytokines, chemokines or hormones; 5) reduction of immunosuppression and/or stimulation of antitumor effector cells using antibodies, small molecules; and 6) various cytoreductive modalities. The authors envisage that combined immunotherapeutic strategies will allow for substantial improvements in clinical outcomes in the near future.

Chemical Synthesis of GM2 Glycans, Bioconjugation with Bacteriophage Qβ, and the Induction of Anticancer Antibodies

The development of carbohydrate-based antitumor vaccines is an attractive approach towards tumor prevention and treatment. Herein, we focused on the ganglioside GM2 tumor-associated carbohydrate antigen (TACA), which is overexpressed in a wide range of tumor cells. GM2 was synthesized chemically and conjugated with a virus-like particle derived from bacteriophage Qβ. Although the copper-catalyzed azide-alkyne cycloaddition reaction efficiently introduced 237 copies of GM2 per Qβ, this construct failed to induce significant amounts of anti-GM2 antibodies compared to the Qβ control. In contrast, GM2 immobilized on Qβ through a thiourea linker elicited high titers of IgG antibodies that recognized GM2-positive tumor cells and effectively induced cell lysis through complement-mediated cytotoxicity. Thus, bacteriophage Qβ is a suitable platform to boost antibody responses towards GM2, a representative member of an important class of TACA: the ganglioside.

Effects of the multiple O-glycosylation states on antibody recognition of the immunodominant motif in MUC1 extracellular tandem repeats

The conformational impact of the clusteredO-glycans strongly influences recognition by antibodies of the cancer-relevant epitope in the MUC1 extracellular tandem repeat domain.

Sialylation: an Avenue to Target Cancer Cells

Tumorigenesis and metastasis are frequently associated with altered structure and expression of oligosaccharides on cell surface glycoproteins and glycolipids. The expression of sialylated glycoconjugates has been shown to change during development, differentiation, disease and oncogenic transformation. Abnormal sialylation in cancer cell is a distinctive feature associated with malignant properties including invasiveness and metastatic potential. The alterations in sialylation is accompanied by changes in sialic acid, sialidase activity, sialyltransferase (ST) activity or sialoproteins. The present review summarizes the reports on alterations of sialic acid, linkage specific STs and sialoproteins, sialidase activity together with different subtypes of ST and sialidases mRNA expressions in various cancers like lung, breast, oral, cervical, ovarian, pancreatic etc. Sialic acids are widely distributed in nature as terminal sugars of oligosaccharides attached to proteins or lipids. The increase shedding of sialic acid observed in malignant tumors may be due to different types of sialidases. The amount of sialic acid is governed by levels of sialidases and STs. Various types of STs are also involved in formation of different types sialylated tumor associated carbohydrate antigens which plays important role in metastasis. The alterations associated with sialylation aids in early diagnosis, prognosis and post treatment monitoring in various cancers. Recently newer drugs targeting different interplays of sialylation have been developed, which might have profound effect in inhibiting sialylation and thus cancer metastasis and infiltration.

Exploring Glycan Markers for Immunotyping and Precision-targeting of Breast Circulating Tumor Cells

BACKGROUND AND AIMS

Recognition of abnormal glycosylation in virtually every cancer type has raised great interest in exploration of the tumor glycome for biomarker discovery. Identifying glycan markers of circulating tumor cells (CTCs) represents a new development in tumor biomarker discovery. The aim of this study was to establish an experimental approach to enable rapid screening of CTCs for glycan marker identification and characterization.

METHODS

We applied carbohydrate microarrays and a high-speed fiber-optic array scanning technology (FAST scan) to explore potential glycan markers of breast CTCs (bCTCs) and targeting antibodies. An anti-tumor monoclonal antibody, HAE3-C1 (C1), was identified as a key immunological probe in this study.

RESULTS

In our carbohydrate microarray analysis, C1 was found to be highly specific for an O-glycan cryptic epitope, gp(C1). Using FAST-scan technology, we established a procedure to quantify expression levels of gp(C1) in tumor cells. In blood samples from five stage IV metastatic breast cancer patients, the gp(C1) positive CTCs were detected in all subjects; ∼40% of bCTCs were strongly gp(C1) positive. Interestingly, CTCs from a triple-negative breast cancer patient with multiple sites of metastasis were predominantly gp(C1) positive (92.5%, 37/40 CTCs).

CONCLUSIONS

Together we present here a practical approach to examine rare cell expression of glycan markers. Using this approach, we identified an O-core glyco-determinant gp(C1) as a potential immunological target of bCTCs. Given its bCTC-expression profile, this target warrants an extended investigation in a larger cohort of breast cancer patients.

A Fully Synthetic Self-Adjuvanting Globo H-Based Vaccine Elicited Strong T Cell-Mediated Antitumor Immunity

Therapeutic cancer vaccines based on the abnormal glycans expressed on cancer cells, such as the globo H antigen, have witnessed great progress in recent years. For example, the keyhole limpet hemocyanin (KLH) conjugate of globo H has been on clinical trials as a cancer vaccine. However, such vaccines have intrinsic problems, such as inconsistence in eliciting T cell-mediated immunity in cancer patients and difficult quality control. To address the issue, a structurally defined fully synthetic glycoconjugate vaccine composed of globo H and monophosphoryl lipid A (MPLA) was developed. The new vaccine was shown to elicit robust IgG1 antibody responses and T cell-dependent immunity, which is desired for anticancer vaccine, and induce significantly faster and stronger immune responses than the globo H-KLH conjugate. Moreover, it was self-adjuvanting, namely, inducing immune responses without the use of an external adjuvant, thus MPLA was not only a vaccine carrier but also a build-in adjuvant. It was also found that antibodies induced by the new vaccine could selectively bind to and mediate strong complement-dependent cytotoxicity to globo H-expressing MCF-7 cancer cell. All of the results have demonstrated that the globo H-MPLA conjugate is a better cancer vaccine than the globo H-KLH conjugate under experimental conditions and is worth further investigation and development.

Multiple-purpose immunotherapy for cancer

Anti-cancer vaccination is a useful strategy to elicit antitumor immune responses, while overcoming immunosuppressive mechanisms. Whole tumor cells or lysates derived thereof hold more promise as cancer vaccines than individual tumor-associated antigens (TAAs), because vaccinal cells can elicit immune responses to multiple TAAs. Cancer cell-based vaccines can be autologous, allogeneic or xenogeneic. Clinical use of xenogeneic vaccines is advantageous in that they can be most effective in breaking the preexisting immune tolerance to TAAs. An attractive protocol would be to combine vaccinations with immunostimulating and/or immunosuppression-blocking modalities. It is reasonable to anticipate that combined immunotherapeutic strategies will allow for substantial improvements in clinical outcomes in the near future.

The prognostic value of ABO blood group in cancer patients

The antigens of the ABO system are expressed on red blood cell membranes as well as on the surface of several other normal and pathological cells and tissues. Following the first clinical observations more than 60 years ago, the role of ABO blood group in cancer biology has been intensely studied by several investigators, and it is now widely recognised that ABO antigens are associated with the risk of developing several types of tumours, namely pancreatic and gastric cancers. However, whether this association also affects the clinical outcome of cancer patients is less certain. In this narrative review, based on literature data, we discuss the role of ABO blood types as prognostic biomarkers in different types of cancers. The current knowledge of the underlying pathogenic mechanisms of the association is also analysed.

Antigen-specific vaccines for cancer treatment

Vaccines targeting pathogens are generally effective and protective because based on foreign non-self antigens which are extremely potent in eliciting an immune response. On the contrary, efficacy of therapeutic cancer vaccines is still disappointing. One of the major reasons for such poor outcome, among others, is the difficulty of identifying tumor-specific target antigens which should be unique to the tumors or, at least, overexpressed on the tumors as compared to normal cells. Indeed, this is the only option to overcome the peripheral immune tolerance and elicit a non toxic immune response. New and more potent strategies are now available to identify specific tumor-associated antigens for development of cancer vaccine approaches aiming at eliciting targeted anti-tumor cellular responses. In the last years this aspect has been addressed and many therapeutic vaccination strategies based on either whole tumor cells or specific antigens have been and are being currently evaluated in clinical trials. This review summarizes the current state of cancer vaccines, mainly focusing on antigen-specific approaches.

Significant Impact of Immunogen Design on the Diversity of Antibodies Generated by Carbohydrate-Based Anticancer Vaccine

Development of an effective vaccine targeting tumor associated carbohydrate antigens (TACAs) is an appealing approach toward tumor immunotherapy. While much emphasis has been typically placed on generating high antibody titers against the immunizing antigen, the impact of immunogen design on the diversity of TACA-specific antibodies elicited has been overlooked. Herein, we report that the immunogen structure can significantly impact the breadth and the magnitude of humoral responses. Vaccine constructs that induced diverse TACA-binding antibodies provided much stronger recognition of a variety of Tn positive tumor cells. Optimization of the breadth of the antibody response led to a vaccine construct that demonstrated long lasting efficacy in a mouse tumor model. After challenged with the highly aggressive TA3Ha cells, mice immunized with the new construct exhibited a statistically significant improvement in survival relative to controls (0% vs 50% survival; p < 0.0001). Furthermore, the surviving mice developed long-term immunity against TA3Ha. Thus, both the magnitude and the breadth of antibody reactivity should be considered when designing TACA-based antitumor vaccines.

The Role of Glycosylation in Breast Cancer Metastasis and Cancer Control

Glycosylation and its correlation to the formation of remote metastasis in breast cancer had been an important scientific topic in the last 25 years. With the development of new analytical techniques, new insights were gained on the mechanisms underlying metastasis formation and the role of aberrant glycosylation within. Mucin-1 and Galectin were recognized as key players in glycosylation. Interestingly, aberrant carbohydrate structures seem to support the development of brain metastasis in breast cancer patients, as changes in glycosylation structures facilitate an overcoming of blood–brain barrier. Changes in the gene expression of glycosyltransferases are the leading cause for a modification of carbohydrate chains, so that also altered gene expression plays a role for glycosylation. In consequence, glycosylation and changes within can be useful for cancer diagnosis, determination of tumor stage, and prognosis, but can as well be targets for therapeutic strategies. Thus, further research on this topic would worthwhile for cancer combating.

Differential N-Glycosylation Patterns in Lung Adenocarcinoma Tissue

To decrease the mortality of lung cancer, better screening and diagnostic tools as well as treatment options are needed. Protein glycosylation is one of the major post-translational modifications that is altered in cancer, but it is not exactly clear which glycan structures are affected. A better understanding of the glycan structures that are differentially regulated in lung tumor tissue is highly desirable and will allow us to gain greater insight into the underlying biological mechanisms of aberrant glycosylation in lung cancer. Here, we assess differential glycosylation patterns of lung tumor tissue and nonmalignant tissue at the level of individual glycan structures using nLC-chip-TOF-MS. Using tissue samples from 42 lung adenocarcinoma patients, 29 differentially expressed (FDR < 0.05) glycan structures were identified. The levels of several oligomannose type glycans were upregulated in tumor tissue. Furthermore, levels of fully galactosylated glycans, some of which were of the hybrid type and mostly without fucose, were decreased in cancerous tissue, whereas levels of non- or low-galactosylated glycans mostly with fucose were increased. To further assess the regulation of the altered glycosylation, the glycomics data was compared to publicly available gene expression data from lung adenocarcinoma tissue compared to nonmalignant lung tissue. The results are consistent with the possibility that the observed N-glycan changes have their origin in differentially expressed glycosyltransferases. These results will be used as a starting point for the further development of clinical glycan applications in the fields of imaging, drug targeting, and biomarkers for lung cancer.

Cancer serum biomarkers based on aberrant post-translational modifications of glycoproteins: Clinical value and discovery strategies

Due to the increase in life expectancy in the last decades, as well as changes in lifestyle, cancer has become one of the most common diseases both in developed and developing countries. Early detection remains the most promising approach to improve long-term survival of cancer patients and this may be achieved by efficient screening of biomarkers in biological fluids. Great efforts have been made to identify specific alterations during oncogenesis. Changes at the cellular glycosylation profiles are among such alterations. The "glycosylation machinery" of cells is affected by malignant transformation due to the altered expression of glycogens, leading to changes in glycan biosynthesis and diversity. Alterations in the post-translational modifications of proteins that occur in cancer result in the expression of antigenically distinct glycoproteins. Therefore, these aberrant and cancer-specific glycoproteins and the autoantibodies that are produced in response to their presence constitute targets for cancer biomarkers' search. Different strategies have been implemented for the discovery of cancer glycobiomarkers and are herein reviewed, along with their potentialities and limitations. Practical issues related with serum analysis are also addressed, as well as the challenges that this area faces in the near future.

Overexpression of α2,3sialyl T-antigen in breast cancer determined by miniaturized glycosyltransferase assays and confirmed using tissue microarray immunohistochemical analysis

Glycan structure alterations during cancer regulate disease progression and represent clinical biomarkers. The study determined the degree to which changes in glycosyltransferase activities during cancer can be related to aberrant cell-surface tumor associated carbohydrate structures (TACA). To this end, changes in sialyltransferase (sialylT), fucosyltransferase (fucT) and galactosyltransferase (galT) activity were measured in normal and tumor tissue using a miniaturized enzyme activity assay and synthetic glycoconjugates bearing terminal LacNAc Type-I (Galβ1-3GlcNAc), LacNAc Type-II (Galβ1-4GlcNAc), and mucin core-1/Type-III (Galβ1-3GalNAc) structures. These data were related to TACA using tissue microarrays containing 115 breast and 26 colon cancer specimen. The results show that primary human breast and colon tumors, but not adjacent normal tissue, express elevated β1,3GalT and α2,3SialylT activity that can form α2,3SialylatedType-IIIglycans (Siaα2-3Galβ1-3GalNAc). Prostate tumors did not exhibit such elevated enzymatic activities. α1,3/4FucT activity was higher in breast, but not in colon tissue. The enzymology based prediction of enhanced α2,3sialylated Type-III structures in breast tumors was verified using histochemical analysis of tissue sections and tissue microarrays. Here, the binding of two markers that recognize Galβ1-3GalNAc (peanut lectin and mAb A78-G/A7) was elevated in breast tumor, but not in normal control, only upon sialidase treatment. These antigens were also upregulated in colon tumors though to a lesser extent. α2,3sialylatedType-III expression correlated inversely with patient HER2 expression and breast metastatic potential. Overall, enzymology measurements of glycoT activity predict truncated O-glycan structures in tumors. High expression of the α2,3sialylated T-antigen O-glycans occur in breast tumors. A transformation from linear core-1 glycan to other epitopes may accompany metastasis.

Biosynthetic Machinery Involved in Aberrant Glycosylation: Promising Targets for Developing of Drugs Against Cancer

Cancer cells depend on altered metabolism and nutrient uptake to generate and keep the malignant phenotype. The hexosamine biosynthetic pathway is a branch of glucose metabolism that produces UDP-GlcNAc and its derivatives, UDP-GalNAc and CMP-Neu5Ac and donor substrates used in the production of glycoproteins and glycolipids. Growing evidence demonstrates that alteration of the pool of activated substrates might lead to different glycosylation and cell signaling. It is already well established that aberrant glycosylation can modulate tumor growth and malignant transformation in different cancer types. Therefore, biosynthetic machinery involved in the assembly of aberrant glycans are becoming prominent targets for anti-tumor drugs. This review describes three classes of glycosylation, O-GlcNAcylation, N-linked, and mucin type O-linked glycosylation, involved in tumor progression, their biosynthesis and highlights the available inhibitors as potential anti-tumor drugs.

Recent Developments in Synthetic Carbohydrate-Based Diagnostics, Vaccines, and Therapeutics

Glycans are everywhere in biological systems, being involved in many cellular events with important implications for medical purposes. Building upon a detailed understanding of the functional roles of carbohydrates in molecular recognition processes and disease states, glycans are increasingly being considered as key players in pharmacological research. On the basis of the important progress recently made in glycochemistry, glycobiology, and glycomedicine, we provide a complete overview of successful applications and future perspectives of carbohydrates in the biopharmaceutical and medical fields. This review highlights the development of carbohydrate-based diagnostics, exemplified by glycan imaging techniques and microarray platforms, synthetic oligosaccharide vaccines against infectious diseases (e.g., HIV) and cancer, and finally carbohydrate-derived therapeutics, including glycomimetic drugs and glycoproteins.

Protein glycosylation in cancer

Neoplastic transformation results in a wide variety of cellular alterations that impact the growth, survival, and general behavior of affected tissue. Although genetic alterations underpin the development of neoplastic disease, epigenetic changes can exert an equally significant effect on neoplastic transformation. Among neoplasia-associated epigenetic alterations, changes in cellular glycosylation have recently received attention as a key component of neoplastic progression. Alterations in glycosylation appear to not only directly impact cell growth and survival but also facilitate tumor-induced immunomodulation and eventual metastasis. Many of these changes may support neoplastic progression, and unique alterations in tumor-associated glycosylation may also serve as a distinct feature of cancer cells and therefore provide novel diagnostic and even therapeutic targets.

Antibody recognition of carbohydrate epitopes†

Carbohydrate antigens are valuable as components of vaccines for bacterial infectious agents and human immunodeficiency virus (HIV), and for generating immunotherapeutics against cancer. The crystal structures of anti-carbohydrate antibodies in complex with antigen reveal the key features of antigen recognition and provide information that can guide the design of vaccines, particularly synthetic ones. This review summarizes structural features of anti-carbohydrate antibodies to over 20 antigens, based on six categories of glyco-antigen: (i) the glycan shield of HIV glycoproteins; (ii) tumor epitopes; (iii) glycolipids and blood group A antigen; (iv) internal epitopes of bacterial lipopolysaccharides; (v) terminal epitopes on polysaccharides and oligosaccharides, including a group of antibodies to Kdo-containing Chlamydia epitopes; and (vi) linear homopolysaccharides.

Glycosphingolipid synthesis inhibition limits osteoclast activation and myeloma bone disease

Glycosphingolipids (GSLs) are essential constituents of cell membranes and lipid rafts and can modulate signal transduction events. The contribution of GSLs in osteoclast (OC) activation and osteolytic bone diseases in malignancies such as the plasma cell dyscrasia multiple myeloma (MM) is not known. Here, we tested the hypothesis that pathological activation of OCs in MM requires de novo GSL synthesis and is further enhanced by myeloma cell-derived GSLs. Glucosylceramide synthase (GCS) inhibitors, including the clinically approved agent N-butyl-deoxynojirimycin (NB-DNJ), prevented OC development and activation by disrupting RANKL-induced localization of TRAF6 and c-SRC into lipid rafts and preventing nuclear accumulation of transcriptional activator NFATc1. GM3 was the prevailing GSL produced by patient-derived myeloma cells and MM cell lines, and exogenous addition of GM3 synergistically enhanced the ability of the pro-osteoclastogenic factors RANKL and insulin-like growth factor 1 (IGF-1) to induce osteoclastogenesis in precursors. In WT mice, administration of GM3 increased OC numbers and activity, an effect that was reversed by treatment with NB-DNJ. In a murine MM model, treatment with NB-DNJ markedly improved osteolytic bone disease symptoms. Together, these data demonstrate that both tumor-derived and de novo synthesized GSLs influence osteoclastogenesis and suggest that NB-DNJ may reduce pathological OC activation and bone destruction associated with MM.

A rationally designed peptidomimetic biosensor for sialic acid on cell surfaces

We have developed peptidomimetic sialic acid (Sia) biosensors using boronic acid and arginine groups on the peptide backbone. The designed peptides were conjugated to fluorescent streptavidin via biotin enabling the optical labeling of cells. This approach provides unique opportunities to detect Sia composition on the cell surfaces and filopodia.

Synthesis and cell-selective antitumor properties of amino acid conjugated tumor-associated carbohydrate antigen-coated gold nanoparticles

The Thomsen Friedenreich antigen (TFag) disaccharide is a tumor-associated carbohydrate antigen (TACA) found primarily on carcinoma cells and rarely expressed in normal tissue. The TFag has been shown to interact with Galectin-3 (Gal-3), one in a family of β-galactoside binding proteins. Galectins have a variety of cellular functions, and Gal-3 has been shown to be the sole galectin with anti-apoptotic activity. We have previously prepared gold nanoparticles (AuNP) coated with the TFag in various presentations as potential anti-adhesive therapeutic tools or antitumor vaccine platforms. Here we describe the synthesis of TFag-glycoamino acid conjugates attached to gold nanoparticles through a combined alkane/PEG linker, where the TFag was attached to either a serine or threonine amino acid. Particles were fully characterized by a host of biophysical techniques, and along with a control particle carrying hydroxyl-terminated linker units, were evaluated in both Gal-3 positive and negative cell lines. We show that the particles bearing the saccharides selectively inhibited tumor cell growth of the Gal-3 positive cells significantly more than the Gal-3 negative cells. In addition, the threonine-attached TF particles were more potent than the serine-attached constructs. These results support the use of AuNP as antitumor therapeutic platforms, targeted against cell lines that express specific lectins that interact with TFag.

Structural biology of antibody recognition of carbohydrate epitopes and potential uses for targeted cancer immunotherapies

Monoclonal antibodies represent the most successful class of biopharmaceuticals for the treatment of cancer. Mechanisms of action of therapeutic antibodies are very diverse and reflect their ability to engage in antibody-dependent effector mechanisms, internalize to deliver cytotoxic payloads, and display direct effects on cells by lysis or by modulating the biological pathways of their target antigens. Importantly, one of the universal changes in cancer is glycosylation and carbohydrate-binding antibodies can be produced to selectively recognize tumor cells over normal tissues. A promising group of cell surface antibody targets consists of carbohydrates presented as glycolipids or glycoproteins. In this review, we outline the basic principles of antibody-based targeting of carbohydrate antigens in cancer. We also present a detailed structural view of antibody recognition and the conformational properties of a series of related tissue-blood group (Lewis) carbohydrates that are being pursued as potential targets of cancer immunotherapy.

Glycans and cancer: role of N-glycans in cancer biomarker, progression and metastasis, and therapeutics

Glycosylation is catalyzed by various glycosyltransferase enzymes which are mostly located in the Golgi apparatus in cells. These enzymes glycosylate various complex carbohydrates such as glycoproteins, glycolipids, and proteoglycans. The enzyme activity of glycosyltransferases and their gene expression are altered in various pathophysiological situations including cancer. Furthermore, the activity of glycosyltransferases is controlled by various factors such as the levels of nucleotide sugars, acceptor substrates, nucleotide sugar transporters, chaperons, and endogenous lectin in cancer cells. The glycosylation results in various functional changes of glycoproteins including cell surface receptors and adhesion molecules such as E-cadherin and integrins. These changes confer the unique characteristic phenotypes associated with cancer cells. Therefore, glycans play key roles in cancer progression and treatment. This review focuses on glycan structures, their biosynthetic glycosyltransferases, and their genes in relation to their biological significance and involvement in cancer, especially cancer biomarkers, epithelial-mesenchymal transition, cancer progression and metastasis, and therapeutics. Major N-glycan branching structures which are directly related to cancer are β1,6-GlcNAc branching, bisecting GlcNAc, and core fucose. These structures are enzymatic products of glycosyltransferases, GnT-V, GnT-III, and Fut8, respectively. The genes encoding these enzymes are designated as MGAT5 (Mgat5), MGAT3 (Mgat3), and FUT8 (Fut8) in humans (mice in parenthesis), respectively. GnT-V is highly associated with cancer metastasis, whereas GnT-III is associated with cancer suppression. Fut8 is involved in expression of cancer biomarker as well as in the treatment of cancer. In addition to these enzymes, GnT-IV and GnT-IX (GnT-Vb) will be also discussed in relation to cancer.

ABO blood types and cancer risk--a cohort study of 339,432 subjects in Taiwan

BACKGROUND

The associations of laboratory-based ABO phenotypes with cancer risks and mortality have not been systematically determined.

METHODS

The study subjects were 339,432 healthy individuals with laboratory-based blood types from a Taiwan cohort.

RESULTS

Compared to blood type O, blood type A was significantly associated with an elevated risk of stomach cancer incidence (Hazard Ratio [HR], 1.38 [95% CI, 1.11-1.72]) and mortality (HR, 1.38 [95% CI, 1.02-1.86]) compared with blood type O, after adjusting for age, sex, education, smoking, alcohol drinking, physical activity, and body mass index. Non-O blood types were associated with an elevated risk of pancreatic cancer, with blood type B reaching statistical significance for incidence (HR, 1.59 [95% CI, 1.02-2.48]) and mortality (HR, 1.63 [95% CI, 1.02-2.60]). In contrast, kidney cancer risk was inversely associated with blood type AB (HR, 0.41 [95% CI, 0.18-0.93]) compared to type O.

CONCLUSION

Cancer risks vary in people with different ABO blood types, with elevated risks of stomach cancer associated with blood type A and pancreatic cancer associated with non-O blood types (A, B, and AB).

Association of ABO blood group and risk of lung cancer in a multicenter study in Turkey

BACKGROUND

The ABO blood groups and Rh factor may affect the risk of lung cancer.

MATERIALS AND METHODS

We analyzed 2,044 lung cancer patients with serologically confirmed ABO/Rh blood group. A group of 3,022,883 healthy blood donors of Turkish Red Crescent was identified as a control group. We compared the distributions of ABO/Rh blood group between them.

RESULTS

The median age was 62 years (range: 17-90). There was a clear male predominance (84% vs. 16%). Overall distributions of ABO blood groups were significantly different between patients and controls (p=0.01). There were also significant differences between patients and controls with respect to Rh positive vs. Rh negative (p=0.04) and O vs. non-O (p=0.002). There were no statistically significant differences of blood groups with respect to sex, age, or histology.

CONCLUSIONS

In the study population, ABO blood types were associated with the lung cancer. Having non-O blood type and Rh-negative feature increased the risk of lung cancer. However, further prospective studies are necessary to define the mechanisms by which ABO blood type may influence the lung cancer risk.

The Cosmc connection to the Tn antigen in cancer

The Tn antigen is a tumor-associated carbohydrate antigen that is not normally expressed in peripheral tissues or blood cells. Expression of this antigen, which is found in a majority of human carcinomas of all types, arises from a blockage in the normal O-glycosylation pathway in which glycans are extended from the common precursor GalNAcα1-O-Ser/Thr (Tn antigen). This precursor is generated in the Golgi apparatus on newly synthesized glycoproteins by a family of polypeptide α-N-acetylgalactosaminyltransferases (ppGalNAcTs) and then extended to the common core 1 O-glycan Galβ1-3GalNAcα1-O-Ser/Thr (T antigen) by a single enzyme termed the T-synthase (core 1 β3-galactosyltransferase or C1GalT). Formation of the active form of the T-synthase requires a unique molecular chaperone termed Cosmc, encoded by Cosmc on the X-chromosome (Xq24 in humans, Xc3 in mice). Cosmc resides in the endoplasmic reticulum (ER) and prevents misfolding, aggregation, and proteasome-dependent degradation of newly synthesized T-synthase. Loss of expression of active T-synthase or Cosmc can lead to expression of the Tn antigen, along with its sialylated version Sialyl Tn antigen as observed in several cancers. Both genetic and epigenetic pathways, in addition to potential metabolic regulation, can result in abnormal expression of the Tn antigen. Engineered expression of the Tn antigen by disruption of either C1GalT (T-syn) or Cosmc in mice is associated with a tremendous range of pathologies and engineered expression of the Tn antigen in mouse embryos leads to embryonic death. Studies indicate that many membrane glycoproteins expressing the Tn antigen and/or truncated O-glycans may be dysfunctional, due to degradation and/or misfolding. Thus, expression of normal O-glycans is associated with health and homeostasis whereas truncation of O-glycans, e.g. the Tn and/or Sialyl Tn antigens is associated with cancer and other pathologies.

Quantifying the Efficiency of N-Phenyl-D-mannosamine to Metabolically Engineer Sialic Acid on Cancer Cell Surface

A convenient method was developed for the quantification of sialic acids expressed by cells and used to analyze the efficiency of N-phenylacetyl-D-mannosamine (ManNPhAc) to metabolically glycoengineer SKMEL-28 cancer cell. For this purpose, ManNPhAc-cultured cells were treated with 2M acetic acid to release sialic acids, and the products were treated with 1,2-diamino-4,5-methylenedioxybenzene to form the corresponding derivatives that had strong UV absorptions. The reaction mixture was then applied to HPLC-UV analysis to determine the amounts and the ratios of natural sialic acid and its unnatural analog. It was confirmed that after incubation with ManNPhAc SKMEL-28 cell was effectively glycoengineered to express a significant amount of unnatural sialic acid.

A cancer therapeutic vaccine based on clustered Tn-antigen mimetics induces strong antibody-mediated protective immunity

Tumor-associated carbohydrate antigens (TACAs) are key components of cancer vaccines. A variety of vaccines based on native TACAs such as α-Tn have shown immunogenicity and protection in preclinical animal studies, however, their weak immunogenicity, low in vivo instability, and poor bioavailability, have discouraged their further evaluations in clinical studies. A new improved vaccine prototype is reported. It is composed of four clustered Tn-antigen mimetics and a immunogenic peptide epitope that are conjugated to a cyclopeptide carrier. The immunization of mice with this vaccine 1) was safe, 2) induced a strong and long-lasting Tn-specific response with IgM/IgG antibodies able to recognize native carbohydrate antigens; 3) produced high titers of IgG1, IgG2a, and IgG3 antibodies; and 4) produced a significant antibody-dependent regression of tumors and conferred protection. Altogether, these findings pave the way for the clinical development of safe and effective therapeutic vaccines against Tn-expressing cancers.

Immature truncated O-glycophenotype of cancer directly induces oncogenic features

Aberrant expression of immature truncated O-glycans is a characteristic feature observed on virtually all epithelial cancer cells, and a very high frequency is observed in early epithelial premalignant lesions that precede the development of adenocarcinomas. Expression of the truncated O-glycan structures Tn and sialyl-Tn is strongly associated with poor prognosis and overall low survival. The genetic and biosynthetic mechanisms leading to accumulation of truncated O-glycans are not fully understood and include mutation or dysregulation of glycosyltransferases involved in elongation of O-glycans, as well as relocation of glycosyltransferases controlling initiation of O-glycosylation from Golgi to endoplasmic reticulum. Truncated O-glycans have been proposed to play functional roles for cancer-cell invasiveness, but our understanding of the biological functions of aberrant glycosylation in cancer is still highly limited. Here, we used exome sequencing of most glycosyltransferases in a large series of primary and metastatic pancreatic cancers to rule out somatic mutations as a cause of expression of truncated O-glycans. Instead, we found hypermethylation of core 1 β3-Gal-T-specific molecular chaperone, a key chaperone for O-glycan elongation, as the most prevalent cause. We next used gene editing to produce isogenic cell systems with and without homogenous truncated O-glycans that enabled, to our knowledge, the first polyomic and side-by-side evaluation of the cancer O-glycophenotype in an organotypic tissue model and in xenografts. The results strongly suggest that truncation of O-glycans directly induces oncogenic features of cell growth and invasion. The study provides support for targeting cancer-specific truncated O-glycans with immunotherapeutic measures.

Molecular subtyping of metastatic melanoma based on cell ganglioside metabolism profiles

BACKGROUND

In addition to alterations concerning the expression of oncogenes and onco-suppressors, melanoma is characterized by the presence of distinctive gangliosides (sialic acid carrying glycosphingolipids). Gangliosides strongly control cell surface dynamics and signaling; therefore, it could be assumed that these alterations are linked to modifications of cell behavior acquired by the tumor. On these bases, this work investigated the correlations between melanoma cell ganglioside metabolism profiles and the biological features of the tumor and the survival of patients.

METHODS

Melanoma cell lines were established from surgical specimens of AJCC stage III and IV melanoma patients. Sphingolipid analysis was carried out on melanoma cell lines and melanocytes through cell metabolic labeling employing [3-3H]sphingosine and by FACS. N-glycolyl GM3 was identified employing the 14 F7 antibody. Gene expression was assayed by Real Time PCR. Cell invasiveness was assayed through a Matrigel invasion assay; cell proliferation was determined through the soft agar assay, MTT, and [3H] thymidine incorporation. Statistical analysis was performed using XLSTAT software for melanoma hierarchical clustering based on ganglioside profile, the Kaplan-Meier method, the log-rank (Mantel-Cox) test, and the Mantel-Haenszel test for survival analysis.

RESULTS

Based on the ganglioside profiles, through a hierarchical clustering, we classified melanoma cells isolated from patients into three clusters: 1) cluster 1, characterized by high content of GM3, mainly in the form of N-glycolyl GM3, and GD3; 2) cluster 2, characterized by the appearance of complex gangliosides and by a low content of GM3; 3) cluster 3, which showed an intermediate phenotype between cluster 1 and cluster 3. Moreover, our data demonstrated that: a) a correlation could be traced between patients' survival and clusters based on ganglioside profiles, with cluster 1 showing the worst survival; b) the expression of several enzymes (sialidase NEU3, GM2 and GM1 synthases) involved in ganglioside metabolism was associated with patients' survival; c) melanoma clusters showed different malignant features such as growth in soft agar, invasiveness, expression of anti-apoptotic proteins.

CONCLUSIONS

Ganglioside profile and metabolism is strictly interconnected with melanoma aggressiveness. Therefore, the profiling of melanoma gangliosides and enzymes involved in their metabolism could represent a useful prognostic and diagnostic tool.

Carbohydrate-Based Polymers for Immune Modulation

Carbohydrates play prominent roles in immune surveillance and response to infection. Multivalency, molecular weight control, and molecular architecture control are properties that polymer science is well suited to address. Each of these properties has been demonstrated to impact the biological interaction of carbohydrate-bearing chains with their binding partners. This viewpoint highlights synthetic advances and potential applications of carbohydrate-based polymers for immune modulation. It also offers future directions in polymer science necessary for carbohydrate polymers to fulfill their potential as immune modulators.

Carbohydrate-mimetic peptides for pan anti-tumor responses

Molecular mimicry is fundamental to biology and transcends to many disciplines ranging from immune pathology to drug design. Structural characterization of molecular partners has provided insight into the origins and relative importance of complementarity in mimicry. Chemical complementarity is easy to understand; amino acid sequence similarity between peptides, for example, can lead to cross-reactivity triggering similar reactivity from their cognate receptors. However, conformational complementarity is difficult to decipher. Molecular mimicry of carbohydrates by peptides is often considered one of those. Extensive studies of innate and adaptive immune responses suggests the existence of carbohydrate mimicry, but the structural basis for this mimicry yields confounding details; peptides mimicking carbohydrates in some cases fail to exhibit both chemical and conformational mimicry. Deconvolution of these two types of complementarity in mimicry and its relationship to biological function can nevertheless lead to new therapeutics. Here, we discuss our experience examining the immunological aspects and implications of carbohydrate-peptide mimicry. Emphasis is placed on the rationale, the lessons learned from the methodologies to identify mimics, a perspective on the limitations of structural analysis, the biological consequences of mimicking tumor-associated carbohydrate antigens, and the notion of reverse engineering to develop carbohydrate-mimetic peptides in vaccine design strategies to induce responses to glycan antigens expressed on cancer cells.

Prognostic value of ABO blood group in patients with surgically resected colon cancer

Background:

Previous studies supported a link between the ABO blood type and survival for several types of malignancies. Nonetheless, the relationship between ABO blood type and survival in colon cancer patients has not been rigorously evaluated. The goal of this retrospective analysis was to discern the correlations between ABO blood group and colon cancer survival.

Methods:

A total of 1555 colon cancer patients that underwent curative-intent surgery between October 1995 and June 2002 were eligible for this study. The primary outcomes measured were the association between ABO blood group and patient survival.

Results:

Compared with patients with non-AB blood types (blood types A, B, and O), patients with blood type AB were more likely to have better survival. The mean overall survival (OS) of the blood type AB patients was 113.9 months, whereas the mean OS of the non-AB blood type patients was significantly lower, 106.1 months (P<0.001, log-rank test). Compared with patients with blood type AB, the hazard ratios for patients with A, B, and O were 4.37 (95% confidence interval (95% CI), 2.65–7.20), 2.99 (95% CI, 1.81–4.96), and 2.78 (95% CI, 1.69–4.56), respectively.

Conclusions:

Blood type AB is a favourable prognostic factor for patients with colon cancer.

Glycobiology of neuroblastoma: impact on tumor behavior, prognosis, and therapeutic strategies

Neuroblastoma (NB), accounting for 10% of childhood cancers, exhibits aberrant cell-surface glycosylation patterns. There is evidence that changes in glycolipids and protein glycosylation pathways are associated to NB biological behavior. Polysialic acid (PSA) interferes with cellular adhesion, and correlates with NB progression and poor prognosis, as well as the expression of sialyltransferase STX, the key enzyme responsible for PSA synthesis. Galectin-1 and gangliosides, overexpressed and actively shedded by tumor cells, can modulate normal cells present in the tumor microenvironment, favoring angiogenesis and immunological escape. Different glycosyltransferases are emerging as tumor markers and potential molecular targets. Immunotherapy targeting disialoganglioside GD2 rises as an important treatment option. One anti-GD2 antibody (ch14.18), combined with IL-2 and GM-CSF, significantly improves survival for high-risk NB patients. This review summarizes our current knowledge on NB glycobiology, highlighting the molecular basis by which carbohydrates and protein–carbohydrate interactions impact on biological behavior and patient clinical outcome.

Xenogeneic therapeutic cancer vaccines as breakers of immune tolerance for clinical application: to use or not to use?

Accumulation of firm evidence that clinically apparent cancer develops only when malignant cells manage to escape immunosurveillance led to the introduction of tumor immunotherapy strategies aiming to reprogramm the cancer-dysbalanced antitumor immunity and restore its capacity to control tumor growth. There are several immunotherapeutical strategies, among which specific active immunotherapy or therapeutic cancer vaccination is one of the most promising. It targets dendritic cells (DCs) which have a unique ability of inducing naive and central memory T cell-mediated immune response in the most efficient manner. DCs can be therapeutically targeted either in vivo/in situ or by ex vivo manipulations followed by their re-injection back into the same patient. The majority of current DC targeting strategies are based on autologous or allogeneic tumor-associated antigens (TAAs) which possess various degrees of inherent tolerogenic potential. Therefore still limited efficacy of various tumor immunotherapy approaches may be attributed, among various other mechanisms, to the insufficient immunogenicity of self-protein-derived TAAs. Based on such an idea, the use of homologous xenogeneic antigens, derived from different species was suggested to overcome the natural immune tolerance to self TAAs. Xenoantigens are supposed to differ sufficiently from self antigens to a degree that renders them immunogenic, but at the same time preserves an optimal homology range with self proteins still allowing xenoantigens to induce cross-reactive T cells. Here we discuss the concept of xenogeneic vaccination, describe the cons and pros of autologous/allogeneic versus xenogeneic therapeutic cancer vaccines, present the results of various pre-clinical and several clinical studies and highlight the future perspectives of integrating xenovaccination into rapidly developing tumor immunotherapy regimens.

GALNT2 enhances migration and invasion of oral squamous cell carcinoma by regulating EGFR glycosylation and activity

OBJECTIVES

Oral squamous cell carcinoma (OSCC) is one of the leading cancers worldwide. Aberrant glycosylation affects many cellular properties in cancers, including OSCC. This study aimed to explore the role of N-acetylgalactosaminyltransferase 2 (GALNT2) in OSCC.

MATERIALS AND METHODS

Immunohistochemistry was performed to study the expression of GALNT2 in an OSCC tissue microarray. Effects of GALNT2 overexpression and knockdown on cell migration and invasion were analyzed in SAS cells by transwell migration assay and matrigel invasion assay, respectively. The Vicia villosa agglutinin (VVA) pull down assay was conducted to detect changes in O-glycans on acceptor substrates of GALNT2. Cell signaling was analyzed by Western blotting.

RESULTS

GALNT2 was overexpressed in 73% (35/48) of OSCC tissues. Moreover, GALNT2 expression was localized in the invasive front and increased in high grade OSCC. GALNT2 overexpression enhanced migration and invasion of SAS cells triggered by fetal bovine serum (FBS) and epidermal growth factor (EGF). In contrast, GALNT2 knockdown inhibited SAS cell migration and invasion. Furthermore, GALNT2 overexpression enhanced VVA binding to epidermal growth factor receptor (EGFR) and EGF-induced phosphorylation of EGFR and AKT. Conversely, GALNT2 knockdown decreased VVA binding and suppressed activity of EGFR and AKT.

CONCLUSION

GALNT2 is frequently overexpressed in OSCC, especially in the carcinoma cells at the invasive front. GALNT2 overexpression enhances the invasive potential of OSCC cells via modifying O-glycosylation and activity of EGFR. These findings suggest that GALNT2 plays an important role in the invasive behavior of OSCC and that targeting GALNT2 could be a promising approach for OSCC therapy.