This review provides insights on the impact of glycosylation in cancer biology and its influence in the current approaches of targeted cancer therapies in the clinical setting. The roles of ...glycosylation in cancer signaling, tumor progression, and metastasis are reviewed as well as glycans and glycan-binding proteins in tumor immunomodulation. Moreover, the latest reports on glycans influencing targeted therapeutic approaches in cancer are summarized. Finally, we discuss the future challenges of the field, outlining potential applications of glycan-based biomarkers for patient stratification and strategies for improving personalized cancer treatment.
This review provides insights on the impact of glycosylation in cancer biology and its influence in the current approaches of targeted cancer therapies in the clinical setting. The roles of glycosylation in cancer signaling, tumor progression, and metastasis are reviewed as well as glycans and glycan-binding proteins in tumor immunomodulation. Moreover, the latest reports on glycans influencing targeted therapeutic approaches in cancer are summarized. Finally, we discuss the future challenges of the field, outlining potential applications of glycan-based biomarkers for patient stratification and strategies for improving personalized cancer treatment.
With the advent of personalized medicine, there is a movement to develop "smaller" and "smarter" microdevices that are able to distinguish similar cancer subtypes. Tumor cells display major ...differences when compared to their natural counterparts, due to alterations in fundamental cellular processes such as glycosylation. Glycans are involved in tumor cell biology and they have been considered to be suitable cancer biomarkers. Thus, more selective cancer screening assays can be developed through the detection of specific altered glycans on the surface of circulating cancer cells. Currently, this is only possible through time-consuming assays. In this work, we propose the "intelligent" Lab on Fiber (iLoF) device, that has a high-resolution, and which is a fast and portable method for tumor single-cell type identification and isolation. We apply an Artificial Intelligence approach to the back-scattered signal arising from a trapped cell by a micro-lensed optical fiber. As a proof of concept, we show that iLoF is able to discriminate two human cancer cell models sharing the same genetic background but displaying a different surface glycosylation profile with an accuracy above 90% and a speed rate of 2.3 seconds. We envision the incorporation of the iLoF in an easy-to-operate microchip for cancer identification, which would allow further biological characterization of the captured circulating live cells.
Background
The epidermal growth factor receptor (EGFR) is a key protein involved in cancer development. Monoclonal antibodies targeting EGFR are approved for the treatment of metastatic colorectal ...cancer (CRC). Despite the beneficial clinical effects observed in subgroups of patients, the acquisition of resistance to treatment remains a major concern. Protein
N-
glycosylation of cellular receptors is known to regulate physiological processes leading to activation of downstream signaling pathways. In the present study, the role of EGFR-specific terminal ⍺2,6-sialylation was analyzed in modulation of the malignant phenotype of CRC cells and their resistance to monoclonal antibody Cetuximab-based therapy.
Methods
Glycoengineered CRC cell models with specific sialyltransferase
ST6GAL1
expression levels were applied to evaluate EGFR activation, cell surface glycosylation and therapeutic response to Cetuximab.
Results
Glycoproteomic analysis revealed EGFR as a major target of ST6Gal1-mediated ⍺2,6-sialylation in a glycosite-specific manner. Mechanistically, CRC cells with increased ST6Gal1 expression and displaying terminal ⍺2,6-sialylation showed a marked resistance to Cetuximab-induced cytotoxicity. Moreover, we found that this resistance was accompanied by downregulation of EGFR expression and its activation.
Conclusions
Our data indicate that EGFR ⍺2,6-sialylation is a key factor in modulating the susceptibility of CRC cells to antibody targeted therapy, thereby disclosing a potential novel biomarker and providing key molecular information for tailor made anti-cancer strategies.
CD44 isoforms are often upregulated in gastric cancer and have been associated with increased metastatic potential and poor survival. To evaluate the functional impact of O‐glycan truncation on CD44 ...we have analysed glyco‐engineered cancer cell models displaying shortened O‐glycans. Here, we demonstrate that induction of aberrant O‐glycan termination through various molecular mechanisms affects CD44 molecular features. We show that CD44 is a major carrier of truncated O‐glycans and that this truncation is accompanied by an increased hyaluronan binding capacity and affects extracellular shedding. In addition, short O‐glycans promoted the colocalization of CD44v6 with the receptor tyrosine kinase RON and concomitantly increased activation. Our in vitro findings were validated in gastric cancer clinical samples.
•Changes in glycosylation controls tumor progression and metastasis formation.•Aberrant glycosylation affects cell signaling, adhesion and migration.•Glycans are modulators of cell-cell adhesion and ...microenvironment interaction.•Cancer cell glycome and glycan binding proteins regulate the immune response.•Glycan-based biomarkers are useful tools in cancer clinical management.
Tumour metastasis is the main cause of cancer related deaths. Metastasis is an intricate multi-step process that requires the acquisition of several cancer cell features, including the modulation of tumour cell migration, adhesion, invasion, and immune evasion. Changes in the cellular glycosylation are associated with malignant transformation of cancer cells, tumour progression and ultimately, metastasis formation. Glycans have major impact on cellular signalling and on the regulation of tumour cell-cell adhesion and cell-matrix interaction. Glycans drive the interplay between the cancer cells and the tumour microenvironment. In this review, we summarize the roles of glycan alterations in tumour progression, such as acquisition of oncogenic features due to modulation of receptor tyrosine kinases, proteoglycans, cadherins and integrins. We also highlight the importance of key glycan binding proteins such as selectins, siglecs and galectins, which are pivotal in the modulation of immune response. An overview on glycans as cancer biomarkers is also presented.
Extracellular vesicles (EVs) are a heterogeneous group of small secreted particles involved in intercellular communication and mediating a broad spectrum of biological functions. EVs cargo is ...composed of a large repertoire of molecules, including glycoconjugates. Herein, we report the first study on the impact of the isolation strategy on the EV populations' glycosylation profile. The use of different state-of-the-art protocols, namely differential ultracentrifugation (UC), total exosome isolation (TEI), OptiPrep
TM
density gradient (ODG) and size exclusion chromatography (SEC) resulted in EV populations displaying different sets of glycoconjugates. The EV populations obtained by UC, ODG and SEC methods displayed similar protein and glycan profiles, whereas TEI methodology isolated the most distinct EV population. In addition, ODG and SEC isolation protocols provided an enhanced EV glycoproteins detection. Remarkably, proteins displaying the tumour-associated glycan sialyl-Tn (STn) were identified as packaged cargo into EVs independently of the isolation methodology. STn carrying EV samples isolated by UC, ODG and SEC presented a considerable set of cancer-related proteins that were not detected in EVs isolated by TEI. Our work demonstrates the impact of using different isolation methodologies in the populations of EVs that are obtained, with consequences in the glycosylation profile of the isolated population. Furthermore, our results highlight the importance of selecting adequate EV isolation protocols and cell culture conditions to determine the structural and functional complexity of the EV glycoconjugates.
In the scenario of personalized medicine, targeted therapies are currently the focus of cancer drug development. These drugs can block the growth and spread of tumor cells by interfering with key ...molecules involved in malignancy, such as receptor tyrosine kinases (RTKs). MET and Recepteur d'Origine Nantais (RON), which are RTKs frequently overactivated in gastric cancer, are glycoprotein receptors whose activation have been shown to be modulated by the cellular glycosylation. In this work, we address the role of sialylation in gastric cancer therapy using an innovative 3D high-throughput cell culture methodology that mimics better the in vivo tumor features. We evaluate the response to targeted treatment of glycoengineered gastric cancer cell models overexpressing the sialyltransferases ST3GAL4 or ST3GAL6 by subjecting 3D spheroids to the tyrosine kinase inhibitor crizotinib. We show here that 3D spheroids of ST3GAL4 or ST3GAL6 overexpressing MKN45 gastric cancer cells are less affected by the inhibitor. In addition, we disclose a potential compensatory pathway via activation of the Insulin Receptor upon crizotinib treatment. Our results suggest that cell sialylation, in addition of being involved in tumor progression, could play a critical role in the response to tyrosine kinase inhibitors in gastric cancer.
Organoids enable in vitro modeling of complex developmental processes and disease pathologies. Like most 3D cultures, organoids lack sufficient oxygen supply and therefore experience cellular stress. ...These negative effects are particularly prominent in complex models, such as brain organoids, and can affect lineage commitment. Here, we analyze brain organoid and fetal single‐cell RNA sequencing (scRNAseq) data from published and new datasets, totaling about 190,000 cells. We identify a unique stress signature in the data from all organoid samples, but not in fetal samples. We demonstrate that cell stress is limited to a defined subpopulation of cells that is unique to organoids and does not affect neuronal specification or maturation. We have developed a computational algorithm, Gruffi, which uses granular functional filtering to identify and remove stressed cells from any organoid scRNAseq dataset in an unbiased manner. We validated our method using six additional datasets from different organoid protocols and early brains, and show its usefulness to other organoid systems including retinal organoids. Our data show that the adverse effects of cell stress can be corrected by bioinformatic analysis for improved delineation of developmental trajectories and resemblance to in vivo data.
Synopsis
Cellular stress in 3D organoids due to insufficient oxygen transport can affect faithful lineage commitment and disease modeling. This work identifies a subpopulation of stressed cells characterized by a distinct gene expression signature that can be removed from scRNAseq datasets for better evaluation of fetal developmental trajectories.
ER‐ and glycolytic stress are found accross organoid protocols.
Stressed cells in 3D organoids form a separate cell state that is not found in vivo and that can be separated bioinformatically.
The presence of stressed cells in organoids does not affect cell‐type specification or the maturation of non‐stressed neurons.
Granular functional filtering (Gruffi) removes stressed cells from the single‐cell datasets but retains cell types found in vivo.
Stress removal leads to clearer developmental trajectories.
A unique stress signature found in in brain organoid samples but not in fetal samples can be quantified and removed from scRNAseq datasets using a new algorithm.
Cellular glycosylation plays a pivotal role in several molecular mechanisms controlling cell⁻cell recognition, communication, and adhesion. Thus, aberrant glycosylation has a major impact on the ...acquisition of malignant features in the tumor progression of patients. To mimic these in vivo features, an innovative high-throughput 3D spheroid culture methodology has been developed for gastric cancer cells. The assessment of cancer cell spheroids' physical characteristics, such as size, morphology and solidity, as well as the impact of glycosylation inhibitors on spheroid formation was performed applying automated image analysis. A detailed evaluation of key glycans and glycoproteins displayed by the gastric cancer spheroids and their counterpart cells cultured under conventional 2D conditions was performed. Our results show that, by applying 3D cell culture approaches, the model cell lines represented the differentiation features observed in the original tumors and the cellular glycocalix underwent striking changes, displaying increased expression of cancer-associated glycan antigens and mucin MUC1, ultimately better simulating the glycosylation phenotype of the gastric tumor.
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