Glycoproteomic Analysis of Serum from Patients with Gastric Precancerous Lesions

Abstract

Gastric cancer is preceded by a carcinogenesis pathway that includes gastritis caused by Helicobacter pylori infection, chronic atrophic gastritis that may progress to intestinal metaplasia (IM), dysplasia, and ultimately gastric carcinoma of the more common intestinal subtype. The identification of glycosylation changes in circulating serum proteins in patients with precursor lesions of gastric cancer is of high interest and represents a source of putative new biomarkers for early diagnosis and intervention. This study applies a glycoproteomic approach to identify altered glycoproteins expressing the simple mucin-type carbohydrate antigens T and STn in the serum of patients with gastritis, IM (complete and incomplete subtypes), and control healthy individuals. The immunohistochemistry analysis of the gastric mucosa of these patients showed expression of T and STn antigens in gastric lesions, with STn being expressed only in IM. The serum glycoproteomic analysis using 2D-gel electrophoresis, Western blot, and MALDI-TOF/TOF mass spectrometry led to the identification of circulating proteins carrying these altered glycans. One of the glycoproteins identified was plasminogen, a protein that has been reported to play a role in H. pylori chronic infection of the gastric mucosa and is involved in extracellular matrix modeling and degradation. Plasminogen was further characterized and showed to carry STn antigens in patients with gastritis and IM. These results provide evidence of serum proteins displaying abnormal O-glycosylation in patients with precursor lesions of gastric carcinoma and include a panel of putative targets for the non-invasive clinical diagnosis of individuals with gastritis and IM.

Glycosylation in cancer: mechanisms and clinical implications

“…Recently, STn antigen was found in circulating CD44 in serum from patients with gastric cancer 200 . In addition, STn has been found in plasminogen in serum from patients with intestinal metaplasia and gastric carcinoma 203 . Additional studies showed altered glycosylation (both fucosylation and sialylation) in PSA as a specific biomarker for prostate cancer that is able to distinguish it from benign prostate hyperplasia 187,204 .…”

Proteomic profiling of gill GSTs in Mytilus galloprovincialis from the North of Portugal and Galicia evidences variations at protein isoform level with a possible relation with water quality

“…Several of the highest intensity and/or relevant non-tryptic peaks were selected for MS/MS analysis. Proteins were identified by combination of Peptide Mass Fingerprint and MS/MS as previously described (Gomes et al, 2013). Proteins were searched in a locally stored copy UniProtKB protein sequence knowledgebase for the taxonomic selection Mollusca (2013_10) using the Mascot search engine (Version 2.4) (Perkins et al, 1999).…”

Probing the O-Glycoproteome of Gastric Cancer Cell Lines for Biomarker Discovery*

“…In addition, STn expression is associated with carcinoma aggressiveness and poor prognosis (15,19). We have recently described the presence of a few STn bearing glycoproteins in serum from individuals with gastric cancer and gastric cancer precursor lesions (20). The biosynthetic and genetic mechanisms underlying the expression of this truncated O-glycan in cancer have remained poorly understood, and a number of mechanisms have been proposed that may not be mutually exclusive.…”