Identification of gel-separated tumor marker proteins by mass spectrometry

Ann Charlotte Bergman, Timothy Benjamin, Ayodele Alaiya, Mark Waltham, Kazuyazu Sakaguchi, Bo Franzén, Stig Linder, Tomas Bergman, Gert Auer, Ettore Appella, Peter J. Wirth, Hans Jörnvall

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101 Citations (Scopus)

Abstract

Two-dimensional gel electrophoresis with subsequent analysis by mass spectrometry was applied to study differences in protein expression between benign and malignant solid tumors from human beast, lung and ovary cells. Cells from freshly resected clinical material were lysed and the extracts were subjected to isoelectric focusing with immobilized pH gradients followed by second-dimensional separation on 10-13% sodium dodecyl sulfate (SDS)/polyacrylamide gels. Polypeptides were identified using matrix-assisted laser desorption/ionization and electrospray ionization mass spectrometry after in-gel protein digestion. Some of the upregulated polypeptides in malignant cells are of potential importance as markers of tumor proliferation. Twenty such proteins were identified, ten constituting novel identifications and ten sequence verifications of previously gel-matched proteins. The proteins identified span a wide range of functions, but several cases of protein truncation were found. Truncated forms of cytokeratins 6D and 8, and of cathepsin D were identified. Truncated froms of these overexpressed proteins support the presence of proteolytic processing steps in tumor material. The protein processing and the difference between protein and mRNA abundancies in tumors of different malignancy and origin suggest that studies at the protein level are important for an understanding of tumor phenotypes.

Original languageEnglish
Pages (from-to)679-686
Number of pages8
JournalElectrophoresis
Volume21
Issue number3
DOIs
Publication statusPublished - 1 Jan 2000
Externally publishedYes

Keywords

  • Mass spectrometry
  • Tumor markers
  • Two-dimensional gel electrophoresis

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