title: Identification of PSME3 as a novel serum tumor marker for colorectal cancer by combining two-dimensional polyacrylamide gel electrophoresis with a strictly mass spectrometry-based approach for data analysis.
abstract: The purpose of this study was to identify and validate novel serological protein biomarkers of human colorectal cancer (CRC). Proteins from matched CRC and adjacent normal tissue samples were resolved by two-dimensional gel electrophoresis. From each gel all spots were excised, and enveloped proteins were identified by MS. By comparison of the resulting protein profiles, dysregulated proteins can be identified. A list of all identified proteins and validation of five exemplarily selected proteins, elevated in CRC was reported previously (Roessler, M., Rollinger, W., Palme, S., Hagmann, M. L., Berndt, P., Engel, A. M., Schneidinger, B., Pfeffer, M., Andres, H., Karl, J., Bodenmuller, H., Ruschoff, J., Henkel, T., Rohr, G., Rossol, S., Rosch, W., Langen, H., Zolg, W., and Tacke, M. (2005) Identification of nicotinamide N-methyltransferase as a novel serum tumor marker for colorectal cancer. Clin. Cancer Res. 11, 6550-6557). Here we describe identification and initial validation of another potential marker protein for CRC. Comparison of tissue protein profiles revealed strong elevation of proteasome activator complex subunit 3 (PSME3) expression in CRC tissue. This dysregulation was not detectable based on the spot pattern. The PSME3-containing spot on tumor gels showed no visible difference to the corresponding spot on matched control gels. MS analysis revealed the presence of two proteins, PSME3 and annexin 4 (ANXA4) in one and the same spot on tumor gels, whereas the matched spot contained only one protein, ANXA4, on control gels. Therefore, dysregulation of PSME3 was masked by ANXA4 and could only be recognized by MS-based analysis but not by image analysis. To validate this finding, antibody to PSME3 was developed, and up-regulation in CRC was confirmed by Western blot analysis and immunohistochemistry. Finally by developing a highly sensitive immunoassay, PSME3 could be detected in human sera and was significantly elevated in CRC patients compared with healthy donors and patients with benign bowel disease. We propose that PSME3 be considered a novel serum tumor marker for CRC that may have significance in the detection and in the management of patients with this disease. Further studies are needed to fully assess the potential clinical value of this marker candidate.
authors.affiliation: Centralized Diagnostics, Roche Diagnostics GmbH, Nonnenwald 2, D-82377 Penzberg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Roessler
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rollinger
authors.forename: Liliana
authors.initials: L
authors.lastname: Mantovani-Endl
authors.forename: Marie-Luise
authors.initials: ML
authors.lastname: Hagmann
authors.forename: Stefan
authors.initials: S
authors.lastname: Palme
authors.forename: Peter
authors.initials: P
authors.lastname: Berndt
authors.forename: Alfred M
authors.initials: AM
authors.lastname: Engel
authors.forename: Michael
authors.initials: M
authors.lastname: Pfeffer
authors.forename: Johann
authors.initials: J
authors.lastname: Karl
authors.forename: Heinz
authors.initials: H
authors.lastname: Bodenmüller
authors.forename: Josef
authors.initials: J
authors.lastname: Rüschoff
authors.forename: Thomas
authors.initials: T
authors.lastname: Henkel
authors.forename: Gerhard
authors.initials: G
authors.lastname: Rohr
authors.forename: Siegbert
authors.initials: S
authors.lastname: Rossol
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rösch
authors.forename: Hanno
authors.initials: H
authors.lastname: Langen
authors.forename: Werner
authors.initials: W
authors.lastname: Zolg
authors.forename: Michael
authors.initials: M
authors.lastname: Tacke
mesh_terms: D000595:Amino Acid Sequence; D001324:Autoantigens / Q000032:analysis / Q000097:blood*; D014408:Biomarkers, Tumor / Q000032:analysis / Q000097:blood*; D015179:Colorectal Neoplasms / Q000737:chemistry / Q000175:diagnosis*; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D007150:Immunohistochemistry; D013058:Mass Spectrometry / Q000379:methods*; D008969:Molecular Sequence Data; D046988:Proteasome Endopeptidase Complex / Q000032:analysis / Q000097:blood*
chemical_list: D001324:Autoantigens; D014408:Biomarkers, Tumor; C099558:Ki antigen; D046988:Proteasome Endopeptidase Complex