Abstract 2213: Aberrant glycoprotein expression in recurrent and non-recurrent prostate cancer tissue
Authors: Totten Sarah M. , Tanimoto Cheylene , Bermudez Abel , Hembree Amy , Brooks James D. , Pitteri Sharon J. 
Published: July 2017

The primary aim of this study is to identify and quantify aberrancies in glycosylation patterns and glycoprotein levels expressed in high grade prostate cancer tissue from men with and without recurrence following radical prostatectomy using multi-dimensional chromatography and tandem mass spectrometry techniques. Glycosylation is a common and highly complex posttranslational modification, and is linked to protein function. Elucidating specific glycan structures is key to understanding the underlying role glycosylation plays in regulating cellular activity, including tumorigenesis, invasion, and metastasis. Aberrant glycosylation is an emerging hallmark of various cancers, demonstrating that alterations in glycosylation disrupt cellular behavior in key pathways. Furthermore, comprehensive glycan characterization can lead to more effective biomarkers with increased clinical utility for distinguishing indolent disease from cancers that are more likely to become metastatic, recur and/or pose higher risk.

In this study, glycoproteomic analysis was performed on prostate cancer tissue and matched normal prostate tissue from ten men with high grade prostate cancer (Gleason 7/8) - five of which experienced recurrence. Proteins were extracted from tissue lysates, denatured, reduced and alkylated. Isotopic labels for quantitation were incorporated during alkylation - normal and cancer tissue was labeled with 12C and 13C acrylamide respectively. Paired normal/cancer tissues were combined. Glycosylated proteins from each pair were separated by multi-lectin chromatography designed to capture sialylated, core-fucosylated, and highly branched complex glycans, fractionating the complex mixture into four discrete fractions containing specific glycoforms. LC-MS/MS was used to analyze the tryptic digest from each fraction for protein identification and quantitation.

This experimental design reveals differences between the glycosylation patterns and protein levels of cancerous and normal tissue in ten men, but also allows for the comparison between those with recurrent cancers. The glycosylation patterns across hundreds of prostate tissue proteins were systematically screened, enabling the detection and relative quantitation of specific glycoforms of proteins that may be dysregulated in prostate cancer. Preliminary results reveal the identification of 6,202 unique proteins, and quantitation of 2,894 proteins, most of which contained sialylated glycoforms. In all patients (regardless of treatment outcome), several hundred proteins had elevated total protein levels in the 13C-labeled cancer tissue compared to the 12C-labeled normal tissue proteins, such as TACSTD2 and LPP, while other proteins demonstrated upregulation only among certain glycoforms. Other glycoproteins were up-regulated in cancer only in recurrent patients, including CPNE1, TXND5, and CASC4.

Citation Format: Sarah M. Totten, Cheylene Tanimoto, Abel Bermudez, Amy Hembree, James D. Brooks, Sharon J. Pitteri. Aberrant glycoprotein expression in recurrent and non-recurrent prostate cancer tissue [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 2213. doi:10.1158/1538-7445.AM2017-2213