Abstract 3008: PSMA glycosylation and aggressive prostate cancer progression

Abstract

Introduction: Prostate cancer has a heterogeneous spectrum of clinical outcomes with phenotypes ranging from indolent asymptomatic cases to very aggressive metastatic and lethal forms. Our long term objective is to identify molecules and characterize mechanisms for PCa progression to aggressive lethal disease. PSMA, a membrane bound glycoprotein is significantly over-expressed in more aggressive and metastatic prostate carcinomas with a negative correlation with patient prognosis. The role of its glycans in disease progression and in the development of biomarkers for the disease and potential therapeutics are currently unknown. Aberrant glycosylation of glycoproteins has been observed in many malignancies, and these changes influence disease progression. Our rationale is that differential glycosylation of PSMA correlates with PCa aggressive disease progression. In this study, we characterize N-linked glycosylation profiles in disease stratified PCa cells and prostate proximal fluids show differential expression of specific PSMA conjugated glycan structures that correlates with aggressive phenotypes. Methods/Results: PSMA was isolation from PCa cell lysates and post-DRE urines by column based affinity chromatography followed by SDS-PAGE and Western Blot and Coomassie staining. The fractionated PSMA protein band was excised and processed for proteomic and glycomic analysis. Isolated PSMA was trypsin digested and treated with PNGaseF and other glycosidases to cleave of N-linked glycans from the peptides. Isolated glycans were subjected to permethylation before MALDI-TOF-MS and high resolution, high mass accuracy and high sensitivity LC/MS/MS on an Orbitrap Fusion Lumos Tribrid MS instrument with multiple fragmentation capabilities (CID, HCD, ETD and EThcD) for glycan identification and quantitation. Validation of differential glycan expression was further performed by targeted glycan based MS and lectin based biochemical technologies. Conclusions: Our preliminary studies show that there is differential expression of PSMA N-linked glycans with disease severity in prostate cancer cells and post DRE urine samples. Further analyses are currently underway using an extensive cohort of post DRE urine samples and additional studies are focusing on uncovering the mechanisms that are modulated by PSMA glycosylation that are responsible for PCa disease progression. These could assist in the development of novel diagnostic and therapeutic strategies for the disease. Citation Format: Tanya C. Burch, Stephen S. Mackay, Ian O. Oduor, Joseph J. Otto, Raymond S. Lance, Dean A. Troyer, Oliver John Semmes, Julius O. Nyalwidhe. PSMA glycosylation and aggressive prostate cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3008.