Analysis of the Effect of Increased α2,3-Sialylation on RTK Activation in MKN45 Gastric Cancer Spheroids Treated with Crizotinib

Nanoparticles targeting Sialyl-Tn for efficient tyrosine kinase inhibitor delivery in gastric cancer

Gastric cancer (GC) is the fourth leading cause of cancer-related deaths worldwide and, therefore, it is urgent to develop new and more efficient therapeutic approaches. Foretinib (FRT) is an oral multikinase inhibitor targeting MET (hepatocyte growth factor receptor) and RON (recepteur d'origine nantais) receptor tyrosine kinases (RTKs) that has been used in clinical trials for several solid tumors. Targeted uptake of therapeutic polymeric nanoparticles (NPs) represents a powerful approach in cancer cell drug delivery. Previously, a nanodelivery system composed of polymeric NPs functionalized with B72.3 antibody, which targets the tumor-associated antigen Sialyl-Tn (STn), has been developed. Herein, these NPs were loaded with FRT to evaluate its capacity in delivering the drug to multicellular tumors spheroids (MCTS) and mouse models. The data indicated that B72.3 functionalized FRT-loaded PLGA-PEG-COOH NPs (NFB72.3) specifically target gastric MCTS expressing the STn glycan (MKN45 SimpleCell (SC) cells), leading to a decrease in phospho-RTKs activation and reduced cell viability. In vivo evaluation using MKN45 SC xenograft mice revealed that NFB72.3 were able to decrease tumor growth, reduce cell proliferation and tumor necrosis. NFB72.3-treated tumors also showed inactivation of phospho-MET and phospho-RON. This study demonstrates the value of using NPs targeting STn for FRT delivery, highlighting its potential as a therapeutic application in GC. STATEMENT OF SIGNIFICANCE: Despite the advances in gastric cancer therapeutics, it remains one of the diseases with the highest incidence and mortality in the world. Combining targeted therapies with a controlled drug release is an attractive strategy to reduce drug cytotoxic effects and improve specific drug delivery efficiency to the cancer cells. Thus, we developed nanoparticles loaded with a tyrosine kinase inhibitor and targeting a specific tumor glycan exclusive of cancer cells. In in vivo gastric cancer xenograft mice models, these nanoparticles efficiently reduced tumor growth, cell proliferation and tumor necrosis area and inactivated phosphorylation of targeting receptors. This approach represents an innovative therapeutic strategy with high impact in gastric cancer.

A roadmap for translational cancer glycoimmunology at single cell resolution

Cancer cells can evade immune responses by exploiting inhibitory immune checkpoints. Immune checkpoint inhibitor (ICI) therapies based on anti-CTLA-4 and anti-PD-1/PD-L1 antibodies have been extensively explored over the recent years to unleash otherwise compromised anti-cancer immune responses. However, it is also well established that immune suppression is a multifactorial process involving an intricate crosstalk between cancer cells and the immune systems. The cancer glycome is emerging as a relevant source of immune checkpoints governing immunosuppressive behaviour in immune cells, paving an avenue for novel immunotherapeutic options. This review addresses the current state-of-the-art concerning the role played by glycans controlling innate and adaptive immune responses, while shedding light on available experimental models for glycoimmunology. We also emphasize the tremendous progress observed in the development of humanized models for immunology, the paramount contribution of advances in high-throughput single-cell analysis in this context, and the importance of including predictive machine learning algorithms in translational research. This may constitute an important roadmap for glycoimmunology, supporting careful adoption of models foreseeing clinical translation of fundamental glycobiology knowledge towards next generation immunotherapies.

Sialyltransferases and Neuraminidases: Potential Targets for Cancer Treatment

Cancers are the leading cause of death, causing around 10 million deaths annually by 2020. The most common cancers are those affecting the breast, lungs, colon, and rectum. However, it has been noted that cancer metastasis is more lethal than just cancer incidence and accounts for more than 90% of cancer deaths. Thus, early detection and prevention of cancer metastasis have the capability to save millions of lives. Finding novel biomarkers and targets for screening, determination of prognosis, targeted therapies, etc., are ways of doing so. In this review, we propose various sialyltransferases and neuraminidases as potential therapeutic targets for the treatment of the most common cancers, along with a few rare ones, on the basis of existing experimental and in silico data. This compilation of available cancer studies aiming at sialyltransferases and neuraminidases will serve as a guide for scientists and researchers working on possible targets for various cancers and will also provide data about the existing drugs which inhibit the action of these enzymes.

alpha2,3 sialic acid processing enzymes expression in gastric cancer tissues reveals that ST3Gal3 but not Neu3 are associated with Lauren's classification, angiolymphatic invasion and histological grade

Gastric cancer (GC) is one of the leading causes of cancer-related deaths worldwide. Despite progress in the last decades, there are still no reliable biomarkers for the diagnosis of and prognosis for GC. Aberrant sialylation is a widespread critical event in the development of GC. Neuraminidases (Neu) and sialyltransferases (STs) regulate the ablation and addition of sialic acid during glycoconjugates biosynthesis, and they are a considerable source of biomarkers in various cancers. This study retrospectively characterized Neu3 and ST3Gal3 expression by immunohistochemistry in 71 paraffin-embedded GC tissue specimens and analyzed the relationship between their expression and the clinicopathological parameters. Neu3 expression was markedly increased in GC tissues compared with non-tumoral tissues (p<0.0001). Intratumoral ST3Gal3 staining was significantly associated with intestinal subtype (p=0.0042) and was negatively associated with angiolymphatic invasion (p=0.0002) and higher histological grade G3 (p=0.0066). Multivariate analysis revealed that ST3Gal3 positivity is able to predict Lauren's classification. No associations were found between Neu3 staining and clinical parameters. The in silico analysis of mRNA expression in GC validation cohorts corroborates the significant ST3Gal3 association with higher histological grade observed in our study. These findings suggest that ST3Gal3 expression may be an indicator for aggressiveness of primary GC.

Role of tumor cell sialylation in pancreatic cancer progression

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies and is currently the third leading cause of cancer death. The aggressiveness of PDAC stems from late diagnosis, early metastasis, and poor efficacy of current chemotherapies. Thus, there is an urgent need for effective biomarkers for early detection of PDAC and development of new therapeutic strategies. It has long been known that cellular glycosylation is dysregulated in pancreatic cancer cells, however, tumor-associated glycans and their cognate glycosylating enzymes have received insufficient attention as potential clinical targets. Aberrant glycosylation affects a broad range of pathways that underpin tumor initiation, metastatic progression, and resistance to cancer treatment. One of the prevalent alterations in the cancer glycome is an enrichment in a select group of sialylated glycans including sialylated, branched N-glycans, sialyl Lewis antigens, and sialylated forms of truncated O-glycans such as the sialyl Tn antigen. These modifications affect the activity of numerous cell surface receptors, which collectively impart malignant characteristics typified by enhanced cell proliferation, migration, invasion and apoptosis-resistance. Additionally, sialic acids on tumor cells engage inhibitory Siglec receptors on immune cells to dampen anti-tumor immunity, further promoting cancer progression. The goal of this review is to summarize the predominant changes in sialylation occurring in pancreatic cancer, the biological functions of sialylated glycoproteins in cancer pathogenesis, and the emerging strategies for targeting sialoglycans and Siglec receptors in cancer therapeutics.

Glycosyltransferases in Cancer: Prognostic Biomarkers of Survival in Patient Cohorts and Impact on Malignancy in Experimental Models

Background: Glycosylation changes are a main feature of cancer. Some carbohydrate epitopes and expression levels of glycosyltransferases have been used or proposed as prognostic markers, while many experimental works have investigated the role of glycosyltransferases in malignancy. Using the transcriptomic data of the 21 TCGA cohorts, we correlated the expression level of 114 glycosyltransferases with the overall survival of patients. Methods: Using the Oncolnc website, we determined the Kaplan−Meier survival curves for the patients falling in the 15% upper or lower percentile of mRNA expression of each glycosyltransferase. Results: Seventeen glycosyltransferases involved in initial steps of N- or O-glycosylation and of glycolipid biosynthesis, in chain extension and sialylation were unequivocally associated with bad prognosis in a majority of cohorts. Four glycosyltransferases were associated with good prognosis. Other glycosyltransferases displayed an extremely high predictive value in only one or a few cohorts. The top were GALNT3, ALG6 and B3GNT7, which displayed a p < 1 × 10−9 in the low-grade glioma (LGG) cohort. Comparison with published experimental data points to ALG3, GALNT2, B4GALNT1, POFUT1, B4GALT5, B3GNT5 and ST3GAL2 as the most consistently malignancy-associated enzymes. Conclusions: We identified several cancer-associated glycosyltransferases as potential prognostic markers and therapeutic targets.

Aberrant Sialylation in Cancer: Biomarker and Potential Target for Therapeutic Intervention?

Simple Summary

Sialylation is a post-translational modification that consists in the addition of sialic acid to growing glycan chains on glycoproteins and glycolipids. Aberrant sialylation is an established hallmark of several types of cancer, including breast, ovarian, pancreatic, prostate, colorectal and lung cancers, melanoma and hepatocellular carcinoma. Hypersialylation can be the effect of increased activity of sialyltransferases and results in an excess of negatively charged sialic acid on the surface of cancer cells. Sialic acid accumulation contributes to tumor progression by several paths, including stimulation of tumor invasion and migration, and enhancing immune evasion and tumor cell survival. In this review we explore the mechanisms by which sialyltransferases promote cancer progression. In addition, we provide insights into the possible use of sialyltransferases as biomarkers for cancer and summarize findings on the development of sialyltransferase inhibitors as potential anti-cancer treatments.

Abstract

Sialylation is an integral part of cellular function, governing many biological processes including cellular recognition, adhesion, molecular trafficking, signal transduction and endocytosis. Sialylation is controlled by the levels and the activities of sialyltransferases on glycoproteins and lipids. Altered gene expression of these enzymes in cancer yields to cancer-specific alterations of glycoprotein sialylation. Mounting evidence indicate that hypersialylation is closely associated with cancer progression and metastatic spread, and can be of prognostic significance in human cancer. Aberrant sialylation is not only a result of cancer, but also a driver of malignant phenotype, directly impacting key processes such as tumor cell dissociation and invasion, cell-cell and cell-matrix interactions, angiogenesis, resistance to apoptosis, and evasion of immune destruction. In this review we provide insights on the impact of sialylation in tumor progression, and outline the possible application of sialyltransferases as cancer biomarkers. We also summarize the most promising findings on the development of sialyltransferase inhibitors as potential anti-cancer treatments.

Galectins as modulators of receptor tyrosine kinases signaling in health and disease

Receptor tyrosine kinases (RTKs) constitute a large group of cell surface proteins that mediate communication of cells with extracellular environment. RTKs recognize external signals and transfer information to the cell interior, modulating key cellular activities, like metabolism, proliferation, motility, or death. To ensure balanced stream of signals the activity of RTKs is tightly regulated by numerous mechanisms, including receptor expression and degradation, ligand specificity and availability, engagement of co-receptors, cellular trafficking of the receptors or their post-translational modifications. One of the most widespread post-translational modifications of RTKs is glycosylation of their extracellular domains. The sugar chains attached to RTKs form a new layer of information, so called glyco-code that is read by galectins, carbohydrate binding proteins. Galectins are family of fifteen lectins implicated in immune response, inflammation, cell division, motility and death. The versatility of cellular activities attributed to galectins is a result of their high abundance and diversity of their cellular targets. A various sugar specificity of galectins and the differential ability of galectin family members to form oligomers affect the spatial distribution and the function of their cellular targets. Importantly, galectins and RTKs are tightly linked to the development, progression and metastasis of various cancers. A growing number of studies points on the close cooperation between RTKs and galectins in eliciting specific cellular responses. This review focuses on the identified complexes between galectins and RTK members and discusses their relevance for the cell physiology both in healthy tissues and in cancer.

The role of O-glycosylation in human disease

O-glycosylation is a highly frequent post-translation modification of proteins, with important functional implications in both physiological and disease contexts. The biosynthesis of O-glycans depends on several layers of regulation of the cellular glycosylation machinery, being organ-, tissue- and cell-specific. This review provides insights on the molecular mechanism underlying O-glycan biosynthesis and modification, and highlights illustrative examples of diseases that are triggered or modulated by aberrant cellular O-glycosylation. Particular relevance is given to genetic disorders of glycosylation, infectious diseases and cancer. Finally, we address the potential of O-glycans and their biosynthetic pathways as targets for novel therapeutic strategies.

Identification of glycogene-type and validation of ST3GAL6 as a biomarker predicts clinical outcome and cancer cell invasion in urinary bladder cancer

Background: Urinary bladder cancer (UBC) is one of the most common causes of morbidity and mortality worldwide characterized by a high risk of invasion and metastasis; however, the molecular classification biomarkers and underlying molecular mechanisms for UBC patient stratification on clinical outcome need to be investigated. Methods: A systematic transcriptomic analysis of 185 glycogenes in the public UBC datasets with survival information and clinicopathological parameters were performed using unsupervised hierarchical clustering. The gene signature for glycogene-type classification was identified using Limma package in R language, and correlated to 8 known molecular features by Gene Set Variation Analysis (GSVA). The clinical relevance and function of a glycogene was characterized by immunohistochemistry in UBC patient samples, and quantitative RT-PCR, Western blotting, promoter activity, MAL II blotting, immunofluorescence staining, wound healing, and transwell assays in UBC cells. Results: A 14-glycogene signature for glycogene-type classification was identified. Among them, ST3GAL6, a glycotransferase to transfer sialic acid to 3'-hydroxyl group of a galactose residue, showed a significant negative association with the subtype with luminal feature in UBC patients (n=2,130 in total). Increased ST3GAL6 was positively correlated to tumor stage, grade, and survival in UBCs from public datasets or our cohort (n=52). Transcription factor GATA3, a luminal-specific marker for UBC, was further identified as a direct upstream regulator of ST3GAL6 to negatively regulate its transactivation. ST3GAL6 depletion decreased MAL II level, cell invasion and migration in 5637 and J82 UBC cells. ST3GAL6 could reverse the effects of GATA3 on global sialylation and cell invasion in SW780 cells. Conclusions: Herein, we successfully identified a novel 14-gene signature for glycogene-type classification of UBC patients. ST3GAL6 gene, from this signature, was demonstrated as a potential biomarker for poor outcomes and cell invasion in UBCs.