The GlyCoCan project considerably advanced our knowledge on the glycosylation of CRC tumor tissues and cell lines. Likewise, effort was put into furthering glycoanalytical technology regarding throughput, sensitivity and analytical depth. N-glycans from colorectal cancer tissues were analyzed with mass spectrometry imaging providing novel insights into glycosylation signatures of the tumor as compared to the neighboring, largely unaffected colon epithelial tissues. Together with the analyses of N-glycans and O-glycans from CRC-derived cell lines, this provided indications for glycosylation fingerprints that are associated with de-differentiation or poor differentiation of CRC cells. Further studies are needed to unravel to which extent these glycosylation features are involved in inducing the cellular molecular switches associated with malignancy.
The GlyCoCan project provided insights into the role of glycans in immunological processes in CRC. In fact, specific glycan structures are recognized by glycan binding proteins and seem to contribute to a down regulation of the immune response, favouring the tumour development. This data is fundamental to better understand CRC mechanism of disease, as well as to pinpoint to novel signatures to stratify CRC patients for the application of immunotherapeutics. With respect to valorisation, monoclonal antibodies were developed that react with specific glycan signatures of CRC. These monoclonal antibodies are able to identify CRC tissues, cell lines, as well as CRC-derived proteins and have potential for diagnosis and targeted therapy. Further studies with larger sample cohorts and pre-clinical models are necessary to validate the added value of these antibodies in the clinics.
Notably, GlyCoCan revealed glycomic serum signatures that allow to discriminate between CRC patients and controls. Glycoproteins from human serum appeared to carry a glycosylation signature with potential for disease staging and prognosis and eventually treatment decisions. In an attempt to further improve the significance of these signatures we analysed the glycosylation of specific blood proteins including immunoglobulins and acute-phase proteins. These analyses allowed to pinpoint to specific glycan attachment sites on particular proteins that appear to be differentially glycosylated with CRC. More specifically, individual glycosylation signatures of each of the examined proteins (immunoglobulin A and G, haptoglobin) showed a potential as disease biomarker. Of note, next to N-glycosylation, also O-glycosylation of plasma proteins (namely immunoglobulin A) was associated with CRC. Further research into the validity of the newly discovered disease markers as well as into suitable detection technology will be needed to replicate these CRC glycosylation signatures and evaluate their clinical benefit.
