title: Overexpression of cathepsin B in gastric cancer identified by proteome analysis.
abstract: We aimed to validate an analytical approach based on proteomics on gastric cancer specimens for the identification of new putative diagnostic or prognostic markers. Primary screening was performed on gastrectomy specimens obtained from ten consecutive patients with gastric cancer. Gastric epithelial cells were obtained with an epithelial cell enrichment technique, homogenized and then separated by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). The differential protein expression pattern was verified stepwise by Western blotting and immunohistochemistry on samples from 28 and 46 cancer patients, respectively. The putative clinical applicability and prognostic use were tested by an enzyme-linked immunoabsorbent assay on serum samples obtained from 149 cancer patients. One hundred-ninety-one differentially expressed protein spots were found by 2-D PAGE and identified by mass spectrometry, including cathepsin B, which was over-expressed in six (60%) patients. Western blotting confirmed that the active form of cathepsin B is over-expressed, while immunohistochemistry showed strong cytoplasmic staining in cancer tissues of 45 (98%) patients. The serum level of cathepsin B was increased in patients with gastric cancer compared to healthy controls (P = 0.0026) and correlated with T-category and the presence of distant metastases (P < 0.05). Serum levels above 129 pmol x L(-1) were associated with a reduced survival rate (P = 0.0297). Proteome analysis is a valuable tool for the identification of prognostic markers in gastric cancer: Increased cathepsin B serum levels are associated with advanced tumor stages and progressive disease, which enables the classification of some gastric cancer patients into a subgroup that should undergo aggressive therapy.
authors.affiliation: Department of Gastroenterology, Hepatology and Infectious Diseases, Otto-von-Guericke University, Magdeburg, Germany. matthias.ebert@medizin.uni-magdeburg.de <matthias.ebert@medizin.uni-magdeburg.de>
authors.forename: Matthias P A
authors.initials: MP
authors.lastname: Ebert
authors.forename: Sabine
authors.initials: S
authors.lastname: Krüger
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Fogeron
authors.forename: Stephanie
authors.initials: S
authors.lastname: Lamer
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Matthias
authors.initials: M
authors.lastname: Pross
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Schulz
authors.forename: Hermann
authors.initials: H
authors.lastname: Lage
authors.forename: Steffen
authors.initials: S
authors.lastname: Heim
authors.forename: Albert
authors.initials: A
authors.lastname: Roessner
authors.forename: Peter
authors.initials: P
authors.lastname: Malfertheiner
authors.forename: Christoph
authors.initials: C
authors.lastname: Röcken
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000096:biosynthesis*; D002401:Cathepsin B / Q000096:biosynthesis* / Q000097:blood; D015180:Electrophoresis, Gel, Two-Dimensional; D004847:Epithelial Cells / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D020543:Proteome / Q000096:biosynthesis*; D013274:Stomach Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D020543:Proteome; D002401:Cathepsin B