Probing the O-glycoproteome of gastric cancer cell lines for biomarker discovery

• Autor(a) principal: Campos, D
• Data de Publicação: 2015
• Outros Autores: Freitas, D, Gomes, J, Magalhães, A, Steentoft, C, Gomes, C, Vester-Christensen, M, Ferreira, JA, Afonso, L, Santos, L, Sousa, J, Mandel, U, Clausen, H, Vakhrushev, SY, Reis, CA
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: https://hdl.handle.net/10216/119038
• topic: Aged; Aged, 80 and over; Biomarkers, Tumor/blood; Biomarkers, Tumor/metabolism; Cell Line, Tumor; Female; Glycoproteins/blood; Glycoproteins/metabolism; Humans; Male; Middle Aged; N-Acetylgalactosaminyltransferases/blood; N-Acetylgalactosaminyltransferases/metabolism; Proteome; Stomach Neoplasms/blood; Stomach Neoplasms/metabolism

Circulating O-glycoproteins shed from cancer cells represent important serum biomarkers for diagnostic and prognostic purposes. We have recently shown that selective detection of cancer-associated aberrant glycoforms of circulating O-glycoprotein biomarkers can increase specificity of cancer biomarker assays. However, the current knowledge of secreted and circulating O-glycoproteins is limited. Here, we used the COSMC KO "Simple- Cell" (SC) strategy to characterize the O-glycoproteome of two gastric cancer SimpleCell lines (AGS, MKN45) as well as a gastric cell line (KATO III) which naturally expresses at least partially truncated O-glycans. Overall, we identified 499 O-glycoproteins and 1236 O-glycosites in gastric cancer SimpleCells, and a total 47 O-glycoproteins and 73 O-glycosites in the KATO III cell line. We next modified the glycoproteomic strategy to apply it to pools of sera from gastric cancer and healthy individuals to identify circulating O-glycoproteins with the STn glycoform. We identified 37 O-glycoproteins in the pool of cancer sera, and only nine of these were also found in sera from healthy individuals. Two identified candidate O-glycoprotein biomarkers (CD44 and GalNAc-T5) circulating with the STn glycoform were further validated as being expressed in gastric cancer tissue. A proximity ligation assay was used to show that CD44 was expressed with the STn glycoform in gastric cancer tissues. The study provides a discovery strategy for aberrantly glycosylated O-glycoproteins and a set of O-glycoprotein candidates with biomarker potential in gastric cancer.