Abstract 202: Comprehensive spatial mapping by MALDI imaging mass spectrometry of the N-glycan tissue glycome and database generation for eighteen tumor types

Abstract

Abstract Glycoproteins account for approximately 80% of the proteins located at the cell surface and in the extracellular environment, and serve as binding ligands for cell adhesion, extracellular matrix molecules, signaling receptors, immune cells, lectins and pathogens. Alterations and changes in cell surface glycosylation during tumorigenesis are well documented, including the major N-linked glycan class of glycosylated proteins. We have recently developed a MALDI imaging mass spectrometry (MALDI-IMS) method to spatially profile N-linked glycans in frozen and formalin-fixed paraffin-embedded (FFPE) tissue sections and tissue microarrays (TMAs). In order to facilitate method development and maximize glycome determinations for many cancer types, we have generated two custom TMAs comprised of multiple tissue core pairs of non-tumor and tumor regions representing eighteen different tumor types (pancreatic, colon, prostate, breast, lung, melanoma, sarcoma, head/neck, kidney, liver, glioma, ovarian, thyroid, uterine, cervical, testicular, gastric, bladder). Tissues are incubated with a molecular coating of peptide N-glycosidase, and released N-glycans are detected directly using MALDI-FTICR imaging, linked directly with tissue histopathology. The method is able to simultaneously identify and distinguish 50 or more components of the N-glycome on a single slide. The approach allows comparison of the similarities and differences in N-glycome compositions across each tumor tissue type, as well determine the relative abundance of each individual glycan across all tumor types. For example, an increase in high mannose glycans is common to many tumor types. From the TMA data, this glycan class is consistently elevated for colon, prostate, lung, breast and bladder cancers, while the other tumor types are variable. Differences in branching complexity, bisecting N-acetylglucs0amine, and the degree of fucosylation and sialylation are also readily evaluable. Additionally, data from each of the TMA core pairs is being compared systematically to the N-glycans detected in the source FFPE blocks. The goal is to generate an extensible reference database of expected N-glycans for each tumor tissue type. This will also provide a framework to expand to other classes of glycans, and complementary glycan data generated by other methods on the same TMA cores. Citation Format: Richard R. Drake, Kacey Talbot, Kim Norris-Caneda, Evelyn Bruner, Peggi M. Angel. Comprehensive spatial mapping by MALDI imaging mass spectrometry of the N-glycan tissue glycome and database generation for eighteen tumor types [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 202. doi:10.1158/1538-7445.AM2017-202