In Situ Analysis of N-Linked Glycans as Potential Biomarkers of Clinical Course in Human Prostate Cancer

Abstract

Prostate cancer is the most common cancer in men worldwide. Despite its prevalence, there is a critical knowledge gap in understanding factors driving disparities in survival among different cohorts of patients with prostate cancer. Identifying molecular features separating disparate populations is an important first step in prostate cancer research that could lead to fundamental hypotheses in prostate biology, predictive biomarker discovery, and personalized therapy. N-linked glycosylation is a cotranslational event during protein folding that modulates a myriad of cellular processes. Recently, aberrant N-linked glycosylation has been reported in prostate cancers. However, the full clinical implications of dysregulated glycosylation in prostate cancer has yet to be explored. Herein, we performed direct on-tissue analysis of N-linked glycans using matrix-assisted laser desorption ionization-mass spectrometry imaging (MALDI-MSI) from tissue microarrays of over 100 patient tumors with over 10 years of follow-up metadata. We successfully identified a panel of N-glycans that are unique between benign and prostate tumor tissue. Specifically, high-mannose as well as tri-and tetra-antennary N-glycans were more abundant in tumor tissue and increase proportionally with tumor grade. Further, we expanded our analyses to examine the N-glycan profiles of Black and Appalachian patients and have identified unique glycan signatures that correlate with recurrence in each population. Our study highlights the potential applications of MALDI-MSI for digital pathology and biomarker discovery for prostate cancer. Implications: MALDI-MSI identifies N-glycan perturbations in prostate tumors compared with benign tissue. This method can be utilized to predict prostate cancer recurrence and study prostate cancer disparities.

Spatial Mapping of Plant N-Glycosylation Cellular Heterogeneity Inside Soybean Root Nodules Provided Insights Into Legume-Rhizobia Symbiosis

“…The N -glycan spatial profiling using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) has emerged over the past few years as a powerful approach in clinical research for insight into aberrant N -glycan structures in specific cell types and histopathological regions during disease progression (Carter et al, 2020 ; Conroy et al, 2021 ; Grzeski et al, 2022 ; Malaker et al, 2022 ; Zhang et al, 2022 ). The method relies on spraying the enzyme peptide N -glycanase (PNGase) over formalin-fixed paraffin-embedded (FFPE) tissue sections to in-situ release the N -linked carbohydrates from their carrier proteins.…”

Glycosylation Changes in Prostate Cancer Progression

“…Here, high mannose glycans were found to be abundant in tumor regions as well as increased tri-and tetraantennary glycans that increased proportionally with tumor grade (19). Furthermore, the triantennary glycan at 2,320 m/z was found to be highly abundant in patients with biochemical recurrence and was correlated with decreased survival by Kaplan-Meier analysis (19). Although not global approaches, several historical studies have utilized human PCa tissue to survey presence or absence of Lewis antigens which are highly associated with malignant transformation (20)(21)(22)(23)(24).…”

“…Here, a human PCa tissue block with both tumor and non-tumor regions was analyzed and it was shown that high mannose glycans (Man5-Man9) were particularly evident in the tumor regions compared to adjacent benign and stroma while multiple biantennary non-sialylated glycans were detected primarily in non-tumor regions (18). A recent study utilized MALDI-IMS to profile a tissue microarray containing prostate tumor tissue (n = 108) and benign tissue (n = 30) from 138 patients (19). Here, high mannose glycans were found to be abundant in tumor regions as well as increased tri-and tetraantennary glycans that increased proportionally with tumor grade (19).…”

“…A recent study utilized MALDI-IMS to profile a tissue microarray containing prostate tumor tissue (n = 108) and benign tissue (n = 30) from 138 patients (19). Here, high mannose glycans were found to be abundant in tumor regions as well as increased tri-and tetraantennary glycans that increased proportionally with tumor grade (19). Furthermore, the triantennary glycan at 2,320 m/z was found to be highly abundant in patients with biochemical recurrence and was correlated with decreased survival by Kaplan-Meier analysis (19).…”

Rewiring of the N-Glycome with Prostate Cancer Progression and Therapy Resistance

“…In contrast, the glycome, which comprises all of the sugar polymers (glycans) synthesized by cells, has remained relatively unexplored in many cancer settings including PCa despite the fact that aberrant glycosylation is a well-known hallmark of cancer [10] and the prostate is a major secreter of glycoproteins [11]. So far, studies on the PCa tumor glycome [12][13][14] have only evaluated early stage disease or, in the setting of CRPC, changes in the serum glycome [15,16], mostly because advanced PCa tissue is usually not available because the tissue is rarely biopsied or resected at this stage of the disease. Unfortunately, changes in the serum glycome are not necessarily tumor derived as systemic hormonal therapy has effects on many tissue types.…”