Ultra-deep glycome and glycoproteome profiling of oral cancer cells, tissues and extracellular vesicles to uncover new prognostic signatures

Abstract

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck malignant tumor and the eighth leading cause of cancer worldwide, with high prevalence and morbidity. Thus, identification of molecular signatures that may assist in the prognostication of patients with OSCC is desperately needed. Interestingly, glycoprofiling of a gingival carcinoma cell line have already indicated lower levels of sialylation and a higher degree of fucosylation compared to levels expressed by a normal oral epithelial cell line from gingiva (Chen et al., 2015), but no systematic clinical correlation between altered protein glycosylation and oral cancer has yet been demonstrated. To this end, this BEPE project aims to uncover new N- and O-linked glycoproteins with prognostic marker potential for OSCC using ultra-sensitive cutting-edge LC-MS/MS methods for glycomics and glycoproteomics at the hosting institution. Encouragingly, we have already identified more than 1,500 proteins and formerly occupied glycoproteins (Asn deamidation upon enzymatic de-N-glycosylation) of circulating extracellular vesicles (EVs) isolated from plasma of OSCC patients using LC-MS/MS in our FAPESP post-doctorate fellowship project (Process 2018/02180-0). Out of a total of 130 proteins that were found to be differentially expressed between patients with (N+) or without (N0) lymph node metastasis, 44 were in fact glycoproteins that showed correlation to the clinical characteristics. To achieve better correlation between the glycosylation changes and clinical outcomes, we need to obtain site-specific and fine structure glycan information of the glycoproteins displayed by OSCC tissues, lowly and highly aggressive OSCC cell lines and their EVs, data that can only be obtained using methods for highly sensitive glycoproteomics and glycomics profiling. Taken together, our preliminary data suggest that the glycosylation signatures of OSCC plasma EVs, tissues and cells may provide new previously overlooked avenues for OSCC prognosis, a hypothesis that will be tested in this BEPE project using cutting-edge LC-MS/MS methods for glycomics and glycoproteomics at the hosting institution. Knowledge transfer of these emerging technologies to the Brazilian lab is an important component of this project.Abstract referenceChen, J.-T. et al. Glycoprotein B7-H3 overexpression and aberrant glycosylation in oral cancer and immune response. Proc. Natl. Acad. Sci. (2015). doi:10.1073/pnas.1516991112.