title: Heat-shock protein 27 (Hsp27) as a target of methylglyoxal in gastrointestinal cancer.
abstract: The molecular mechanisms underlying the posttranslational modification of proteins in gastrointestinal cancer are still unknown. Here, we investigated the role of methylglyoxal modifications in gastrointestinal tumors. Methylglyoxal is a reactive dicarbonyl compound produced from cellular glycolytic intermediates that reacts non-enzymatically with proteins. By using a monoclonal antibody to methylglyoxal-modified proteins, we found that murine heat-shock protein 25 and human heat-shock protein 27 were the major adducted proteins in rat gastric carcinoma mucosal cell line and human colon cancer cell line, respectively. Furthermore, we found that heat-shock protein 27 was modified by methylglyoxal in ascending colon and rectum of patients with cancer. However, methylglyoxal-modified heat-shock protein 25/heat-shock protein 27 was not detected in non cancerous cell lines or in normal subject. Matrix-associated laser desorption/ionization mass spectrometry/mass spectrometry analysis of peptide fragments identified Arg-75, Arg-79, Arg-89, Arg-94, Arg-127, Arg-136, Arg-140, Arg-188, and Lys-123 as methylglyoxal modification sites in heat-shock protein 27 and in phosphorylated heat-shock protein 27. The transfer of methylglyoxal-modified heat-shock protein 27 into rat intestinal epithelial cell line RIE was even more effective in preventing apoptotic cell death than that of native control heat-shock protein 27. Furthermore, methylglyoxal modification of heat-shock protein 27 protected the cells against both the hydrogen peroxide- and cytochrome c-mediated caspase activation, and the hydrogen peroxide-induced production of intracellular reactive oxygen species. The levels of lactate converted from methylglyoxal were increased in carcinoma mucosal cell lines. Our results suggest that posttranslational modification of heat-shock protein 27 by methylglyoxal may have important implications for epithelial cell injury in gastrointestinal cancer.
authors.affiliation: Department of Medical Proteomics, Kyoto Prefectural University of Medicine, 465 Kaji-i, Kyoto 602-8566, Japan. oya-ito@koto.kpu-m.ac.jp
authors.forename: Tomoko
authors.initials: T
authors.lastname: Oya-Ito
authors.forename: Yuji
authors.initials: Y
authors.lastname: Naito
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Takagi
authors.forename: Osamu
authors.initials: O
authors.lastname: Handa
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Matsui
authors.forename: Masaki
authors.initials: M
authors.lastname: Yamada
authors.forename: Keisuke
authors.initials: K
authors.lastname: Shima
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Yoshikawa
mesh_terms: D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D045744:Cell Line, Tumor; D005770:Gastrointestinal Neoplasms / Q000378:metabolism* / Q000473:pathology; D055551:HSP27 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D040901:Proteomics; D011765:Pyruvaldehyde / Q000378:metabolism*; D051381:Rats; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D055551:HSP27 Heat-Shock Proteins; D011765:Pyruvaldehyde