Clusterin glycopeptide variant characterization reveals significant site-specific glycan changes in the plasma of clear cell renal cell carcinoma

Francisca O. Gbormittah, Jonathan Bones, Marina Hincapie, Fateme Tousi, William S. Hancock*, Othon Iliopoulos

*Corresponding author for this work

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Cancer-related alterations in protein glycosylation may serve as diagnostic or prognostic biomarkers or may be used for monitoring disease progression. Clusterin is a medium abundance, yet heavily glycosylated, glycoprotein that is upregulated in clear cell renal cell carcinoma (ccRCC) tumors. We recently reported that the N-glycan profile of clusterin is altered in the plasma of ccRCC patients. Here, we characterized the occupancy and the degree of heterogeneity of individual N-glycosylation sites of clusterin in the plasma of patients diagnosed with localized ccRCC, before and after curative nephrectomy (n = 40). To this end, we used tandem mass spectrometry of immunoaffinity-enriched plasma samples to analyze the individual glycosylation sites in clusterin. We determined the levels of targeted clusterin glycoforms containing either a biantennary digalactosylated disialylated (A2G2S2) glycan or a core fucosylated biantennary digalactosylated disialylated (FA2G2S2) glycan at N-glycosite N374. We showed that the presence of these two clusterin glycoforms differed significantly in the plasma of patients prior to and after curative nephrectomy for localized ccRCC. Removal of ccRCC led to a significant increase in the levels of both FA2G2S2 and A2G2S2 glycans in plasma clusterin. These changes were further confirmed by lectin blotting of plasma clusterin. It is envisioned that these identified glycan alterations may provide an additional level of therapeutic or biomarker sensitivity than levels currently achievable by monitoring expression differences alone.

Original languageEnglish
Pages (from-to)2425-2436
Number of pages12
JournalJournal of Proteome Research
Volume14
Issue number6
DOIs
Publication statusPublished - 5 Jun 2015
Externally publishedYes

Keywords

  • Clear cell renal cell carcinoma
  • clusterin
  • collision-induced dissociation
  • glycoforms
  • N-glycan
  • site-specific analysis

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