title: A novel technique to specifically analyze the secretome of cells and tissues.
abstract: The secretome of cells and tissues may reflect a broad variety of pathological conditions and thus represents a rich source of biomarkers. The identity of secreted proteins, usually isolated from cell supernatants or body fluids, is hardly accessible by direct proteome analysis, because these proteins are often masked by high amounts of proteins actually not secreted by the investigated cells. Here, we present a novel method for the specific detection of proteins secreted by human tissue specimen as well as cultured cells and chose liver as a model. The method is based on the metabolic labelling of proteins synthesized during a limited incubation period. Then, the cell supernatant is filtered, precipitated, and subjected to two-dimensional gel electrophoresis. Whereas fluorography detected a large number of proteins derived from residual plasma and dead cells, the autoradiographs selectively displayed genuinely secreted proteins. We demonstrate the feasibility of this approach by means of the secretomes of the hepatocellular carcinoma-derived cell line HepG2 and human liver slices. The selective identification of cell- and tissue-specific protein secretion profiles may help to identify novel sets of biomarkers for wide clinical applications.
authors.affiliation: Department of Internal Medicine Clinic I, Institute of Cancer Research, Medical University of Vienna, Vienna, Austria.
authors.forename: Hannes
authors.initials: H
authors.lastname: Zwickl
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Traxler
authors.forename: Stefan
authors.initials: S
authors.lastname: Staettner
authors.forename: Wolfram
authors.initials: W
authors.lastname: Parzefall
authors.forename: Bettina
authors.initials: B
authors.lastname: Grasl-Kraupp
authors.forename: Josef
authors.initials: J
authors.lastname: Karner
authors.forename: Rolf
authors.initials: R
authors.lastname: Schulte-Hermann
authors.forename: Christopher
authors.initials: C
authors.lastname: Gerner
mesh_terms: D000595:Amino Acid Sequence; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000378:metabolism; D008969:Molecular Sequence Data; D011506:Proteins / Q000032:analysis / Q000378:metabolism*; D020543:Proteome / Q000032:analysis / Q000378:metabolism*; D040901:Proteomics / Q000379:methods*
chemical_list: D011506:Proteins; D020543:Proteome