A metabolic labeling approach for glycoproteomic analysis reveals altered glycoprotein expression upon GALNT3 knockdown in ovarian cancer cells

作者：Sheta Razan; Woo Christina M; Roux Dalvai Florence; Fournier Frederic; Bourassa Sylvie; Droit Arnaud; Bertozzi Carolyn R; Bachvarov Dimcho^*

来源：Journal of Proteomics, 2016, 145: 91-102.

DOI：10.1016/j.jprot.2016.04.0096

• Epithelial ovarian cancer
• GALNT3
• Glycosylation
• Metabolic labeling
• Glycoproteomics
• Pathway and network analysis

Epithelial ovarian cancer (EOC) is a disease responsible for more deaths among women in the Western world than all other gynecologic malignancies. There is urgent need for new therapeutic targets and a better understanding of EOC initiation and progression. We have previously identified the polypeptide N-acetylgalactosaminyltransferase 3 (GALNT3) gene, a member of the GaINAc-transferases (GaINAc-Ts) gene family, as hypomethylated and overexpressed in high-grade serous EOC tumors, compared to low malignant potential EOC tumors and normal ovarian tissues. This data also suggested for a role of GALNT3 in aberrant EOC glycosylation, possibly implicated in disease progression. To evaluate differential glycosylation in EOC caused by modulations in GALNT3 expression, we used a metabolic labeling strategy for enrichment and mass spectrometry-based characterization of glycoproteins following GALNT3 gene knockdown (KD) in A2780s EOC cells. A total of 589 differentially expressed glycoproteins were identified upon GALNT3 Ka Most identified proteins were involved in mechanisms of cellular metabolic functions, post-translational modifications, and some have been reported to be implicated in EOC etiology.
The GALNT3-dependent glycoproteins identified by this metabolic labeling approach support the oncogenic role of GALNT3 in EOC dissemination and may be pursued as novel EOC biomarkers and/or therapeutic targets. Biological significance: Knowledge of the O-glycoproteome has been relatively elusive, and the functions of the individual polypeptide GaINAc-Ts have been poorly characterized. Alterations in GaINAc-Ts expression were shown to provide huge variability in the )-glycoproteome in various pathologies, including cancer. The application of a chemical biology approach for the metabolic labeling and subsequent characterization of O-glycoproteins in EOC using the Ac(4)GaINAz metabolite has provided a strategy allowing for proteomic discovery of GaINAc-Ts specific functions. Our study supports an essential role of one of the GaINAc-Ts GALNT3, in EOC dissemination, including its implication in modulating PTMs and EOC metabolism.

• 出版日期2016-8-11