Oral Presentation 23rd Annual Lorne Proteomics Symposium 2018

Protein glycosylation features of metastatic melanoma: the search for prognostic markers (#44)

Jodie L Abrahams 1 2 , Matthew P Campbell 1 2 , Nicolle H Packer 1 2
  1. Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, Australia
  2. Institute for Glycomics, Griffith University, Gold Coast, QLD, Australia

Metastasis accounts for the majority of mortality associated with melanoma, as limited treatment options exist for advanced disease stages. The identification of prognostic markers for stage III melanoma is of great importance as currently the survival rate for patients at this stage of disease is highly variable. One avenue that has so far been underexplored in melanoma research is the glycosylation pathway.

Here, we investigate the relationship between cell surface glycosylation, metastatic phenotypes, and patient prognosis, as well as report the first in-depth glycan characterisation of cell surface proteins and the Melanoma Cell Adhesion Molecule (MCAM) from metastatic melanoma samples.

The glycosylation profile of tissue from different patient subgroups including good/poor prognosis, primary histology and disease stage were investigated with an aim to identify any subtype-associated glycan features. In addition, the glycosylation profile of cultured cells was compared to patient tissue.

N- and O-glycans were released from cell membrane protein fractions of lymph node tumours and cultured cells and characterised using a porous graphitized carbon liquid chromatography mass spectrometry glycomics platform. Structures were fully assigned using MS/MS fragmentation patterns, retention behaviours.

The linkages of the glycan monosaccharides were confirmed using an array of exoglycosidase enzymes and glycan structures were quantitated before and after selected exoglycosidase combinations to confirm differences in structural features including the degree of branching, sialylation and fucosylation. The use of this strategy provided additional valuable structural information including confirmation of the presence of polylactosamine chains, linkages of sialic acid residues and previously unreported epitopes including LacdiNAc carried by cell surface proteins. These structural glycan epitopes may play a role in melanoma metastasis.

This study contributes to our understanding of glycosylation alterations in melanoma metastasis, towards using specific glycosylation changes as novel biomarkers for monitoring metastasis and predicting prognosis.