Análise do glicoproteoma sérico de doentes com lesões gástricas pré-neoplásicas

Este estudo permitiu identificar proteínas com glicosilação anómala no soro de doentes com lesões gástricas pré-neoplásicas, abrindo a possibilidade de diagnóstico não invasivo nesse contexto. A abordagem, de estudo do glicoproteoma sérico, identificou entre outras proteínas o plasminogénio como sendo «portador» de formas de glicosilação aberrante. 

Revista:
Journal of Proteome Research

Autores:
Catarina Gomes ¹; Andreia Almeida ²; José Alexandre Ferreira ^2,3; Luísa Silva ¹; Hugo Santos-Sousa ⁴; João Pinto-de-Sousa ^1,4; Lúcio L. Santos ³; Francisco Amado ²; Tilo Schwientek ⁵; Steven B. Levery ⁷; Ulla Mandel ⁷; Henrik Clausen ⁷; Leonor David ^1,4;  Celso A. Reis ^1,4,6; Hugo Osório ^1,4. 

Afiliações:
¹ Institute of Molecular Pathology and Immunology of the University of Porto. IPATIMUP, Porto, Portugal;
² QOPNA, Department of Chemistry of the University of Aveiro, Campus de Santiago, Aveiro, Portugal;
³ Experimental Pathology and Therapeutics Group, Portuguese Institute for Oncology, Porto, Portugal
⁴ Faculty of Medicine, University of Porto, Porto, Portugal
⁵ Center of Biochemistry, University of Cologne, Köln, Germany
⁶ Institute of Biomedical Sciences of Abel Salazar, ICBAS, Porto, Portugal.
⁷ Copenhagen Center for Glycomics, University of Copenhagen, Denmark.

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 sub-types) and in 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.

Legenda da foto:
2D gel electrophoresis and Western blot analysis for STn antigen of serum from healthy individuals and individuals with gastritis. In the left side of the figure are represented Coomassie Blue gels of serum samples equalized with Combinatorial Peptide Ligand Libraries – CPLL, and in the right sides are represented Western blots against STn antigen. The spots highlighted in the Western blots were matched on Coomassie Blue gels and selected for protein identification by MALDI-TOF/TOF analysis.

Link da publicação: 
www.ncbi.nlm.nih.gov/pubmed/23312025