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The Development of Improved Therapeutics through a Glycan- “Designer” Approach
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Throughout the years of research on glycans and their lectin receptors, it has become clear that the glycans not only help to maintain protein intrinsic properties (folding, stability, structure) but also affect the biological pathways and cell-mediated immune processes.
Plant Lectins in Cancer Treatment: The Case of Viscum album L.
Published in Spyridon E. Kintzios, Maria G. Barberaki, Evangelia A. Flampouri, Plants That Fight Cancer, 2019
Lectins display great potential in cancer therapy and diagnosis by being molecules able to specifically recognize carbohydrates on the cellular membrane and their glycosylation resulting from malignancy (Mody et al. 1995). Cancer is a complex process in which genetic alterations affect and modify cell signaling, functioning, replication rhythm, apoptosis, and metastasis. Cancer cells exhibit irregular glycosylation patterns, and this process plays a significant role in cell development, signaling, interaction, proliferation, differentiation, and migration (Estrada-Martínez et al. 2017). During malignant transformation, the glycans express alterations such as over expression of certain structures, loss of expression, the appearance of novel or incomplete structures, and the accumulation of precursors (Varki et al. 2017). Glycan is a term used for any sugar or assembly of sugars, existing in a free form or attached to molecules. Glycans are involved in basic molecular and biological processes occurring in cancer affecting cell signaling, cell–cell and cell–matrix interactions, tumor cell invasion, angiogenesis, immune modulation, and metastasis (Pinho and Reis 2015). The glycosylation of proteins is the key element for a wide variety of biological processes affecting their localization, stability, and folding. Consequently, aberrant glycosylation in malignant cells results in many biological pathways affecting cell signaling, migration, adhesion, and cell death, regulating apoptosis, and autophagy (Korekane and Taniguchi 2015).
The Thymus and Immunotherapy, Reconstructive Vs. Stimulatory or Suppressive Conceptions
Published in Marek P. Dabrowski, Barbara K. Dabrowska-Bernstein, Immunoregulatory Role of Thymus, 2019
Marek P. Dabrowski, Barbara K. Dabrowska-Bernstein
Yet another and clearly unique group of immunomodulators demonstrating adjuvant activities are glucans. They are polysaccharides prepared from an extensive array of single and multicellular fungi. Chemically pure glucans are mainly derived from Saccharomyces cerevisiae (Dirocan), Schizophyllum commune (Schizophyllan or SPG), or Lentinus edodes (already mentioned Lentinan), and represent predominantly beta-1, 3 beta-1,-4, or beta-1, 6 poly glucose helical structures. Glucans and glycans have recently gained increased attention for their clinical potential in infectious diseases, neoplasia, radiation recovery, hemopoietic disorders, and vaccine development, and are currently under extensive experimental and clinical study.219,231,232
GlycoVHH: optimal sites for introducing N-glycans on the camelid VHH antibody scaffold and use for macrophage delivery
Published in mAbs, 2023
Loes van Schie, Wander Van Breedam, Charlotte Roels, Bert Schepens, Martin Frank, Ahmad Reza Mehdipour, Bram Laukens, Wim Nerinckx, Francis Santens, Simon Devos, Iebe Rossey, Karel Thooft, Sandrine Vanmarcke, Annelies Van Hecke, Xavier Saelens, Nico Callewaert
Glycan analysis. While it was clear that we had many good sites for further work, we selected the sites in each loop where we had first identified that the native sequence could be mutated to an N-glycosylation sequon, and for which very high site occupancy was observed. Selected glycovariants Q14N-P15A-G16T, G27N-P30T, P48N-K50T, R86N, K97N-P98A-E99T and E99N (shaded orange in Figure 1c,f) were purified for further characterization (Figure 2a). Endoglycosidase treatment and subsequent SDS-PAGE analysis of the purified proteins confirmed the presence of N-linked glycans on the purified glycovariants (Figure 2b,c), but it was also clear that our nickel-NTA and gel filtration purification strategy had biased to the non-glycosylated minor species, in some cases more than others, likely due to protein peaks running across multiple selected fractions, with peak tails not retained for pooling to the final preparation. Hence, the percentage site-occupancy as determined by the analysis of purified protein is an underestimation.
Breast cancer glycan biomarkers: their link to tumour cell metabolism and their perspectives in clinical practice
Published in Expert Review of Proteomics, 2021
Tomas Bertok, Veronika Pinkova Gajdosova, Aniko Bertokova, Natalia Svecova, Peter Kasak, Jan Tkac
Carbohydrates are the most common type of biomolecules on Earth and are ubiquitous for the most common enzymatic post-translational modification of proteins called glycosylation [26]. Complex carbohydrates – glycans, are a part of many glycoconjugates, such as glycopeptides and glycoproteins, peptidoglycans, glycolipids, lipopolysaccharides, glycosaminoglycans and other glycosides (Figure 2). Most common glycosylation is N- and O-glycosylation, where glycan part is attached to Asn-X-Ser/Thr or Ser/Thr residues, respectively, but there are less abundant glycans such as C-glycans (C-C bond via tryptophan) and the quite unusual S-glycans (C-S bond via cysteine) [27]. Changes in glycan structure and composition caused by different expression of glycan-modifying enzymes, i.e. glycosyltransferases („writers“) and glycosidases („erasers“) [28], are associated with pathological processes – including cancer, promoting cell proliferation, angiogenesis, epithelial-to-mesenchymal transition, migration or extravasation [29,30]. Aberrant glycoforms are present during development and progression of cancer (metastases) and might lead to chemoresistant cell lines [26]. While aberrant glycoforms of some membrane-bound glycoconjugates may directly serve as receptors for some viral hemagglutinins (Influenza virus), membrane-associated mucins create a physical barrier and also a „decoy“ for the pathogens to protect epithelial cells [26].
Glycans: potential therapeutic targets for cholangiocarcinoma and their therapeutic and diagnostic implications
Published in Expert Opinion on Therapeutic Targets, 2021
Glycosylation is an important post-translational modification of cellular glycoprotein by the stepwise addition of sugar residues to form a complex glycan structure. Glycans play essential roles in many biological processes; such as cell-cell communication, cell adhesion, ligand–receptor interaction, self and nonself recognition, etc. Alteration of glycosylation has been considered a hallmark of cancer as it plays important role in tumor development and progression [1]. The aberrant glycosylation is possibly triggered by the overproduction of nucleotide-sugar donors and/or altered expression of glycosyltransferase and glycosidase enzymes [2]. Not only aberrant glycosylation, but the over-expression of carrier-proteins is also an important factor to promote tumor growth and metastasis. These aberrations are possibly the targets for cancer immunotherapy or chemo-sensitization. Also, the cancer-associated glycans and glycoconjugates can possibly be the biomarkers for diagnosis, monitoring, and prognostic prediction of the disease. Collective data in cholangiocarcinoma (CCA) revealed that glycosylation is altered during tumorigenesis and progression of CCA. The CCA-associated glycans were aberrantly expressed and play many essential roles in tumor metastasis and drug resistance, which were possibly used as the targets for CCA treatment. Moreover, the CCA-associated glycans that are elevated in patients’ sera are beneficial as biomarkers for diagnosis and prognosis of CCA.