Tissue glycomics distinguish tumour sites in women with advanced serous adenocarcinoma

In the era of precision medicine, the tailoring of cancer treatment is increasingly important as we transition from organ-based diagnosis towards a more comprehensive and patient-centric molecular diagnosis. This is particularly the case for high-grade serous adenocarcinomas of the ovary and peritoneum, which are commonly diagnosed at an advanced stage, and collectively treated and managed similarly. We characterized the N- and O- glycome of serous ovarian (OC) and peritoneal cancer (PC) tissues using PGC-LC-ESI-IT-MS/MS profiling and validated the discriminatory glycans and their corresponding glyco-gene expression levels using cell lines and transcriptomic data from 232 patients. Overall, the N- and O-glycan repertoire of both cancer types were found to comprise mostly of α2,6-sialylated glycan structures, with the majority of N-glycans displaying both the bi-antennary mono- and di-sialylation as well as bisecting-type bi-antennary glycans. The MS profiling by PGC-LC also revealed several glycan structural isomers that corresponded to LacdiNAc-type (GalNAcβ1-4GlcNAc) motifs that were unique to the serous ovarian cancers and that correlated with elevated gene expression of B4GALNT3 and B4GALNT4 in serous cancer patients. Statistical evaluation of the discriminatory glycans also revealed 13 N- and 3 O-glycans (p < 0.05) that significantly discriminated tumor-sampling sites, with LacdiNAc-type N-glycans (m/z 1205.02- and m/z 1059.42-) being associated with ovarian-derived cancer tissue and bisecting-GlcNAc type (m/z 994.92-) and branched N-glycans (m/z 1294.02- and m/z 1148.42-) upregulated at the metastatic sites. Hence, we demonstrate for the first time, that OC and PC display distinct molecular signatures at both their glycomic and transcriptomics levels. These signatures may have potential utility for the development of accurate diagnosis and personalized treatments. This article is protected by copyright. All rights reserved.