title: Helicobacter pylori induces mono-(adenosine 5'-diphosphate)-ribosylation in human gastric adenocarcinoma.
abstract: Mono-(adenosine 5'-diphosphate) (ADP)-ribosylation, which transfers an ADP-ribose from nicotinamide adenine dinucleotide (NAD) to an acceptor protein, is an important post-translational modification of cellular proteins. Several bacterial toxins are known to possess the mono-ADP-ribosyltransferase activity to catalyze this reaction as a possible pathogenic factor. Therefore, the aim of this study was to examine whether H. pylori may also induce mono-ADP-ribosylation in a human gastric mucosal protein in association with gastric cancer development. Tumorous and adjacent non-tumorous mucosal tissue specimens were obtained from the surgically removed stomachs of 5 patients with gastric adenocarcinoma, and then were homogenized into cytosolic and membranous fractions. Each homogenate or an H. pylori extract was assayed for mono-ADP-ribosylation with [adenylate-(32)P]-NAD and 3-aminobenzamide, a potent inhibitor of poly-ADP-ribosylation. The radiolabeled proteins were separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis followed by radio-image analysis. In the extracts from H. pylori, a strain-dependent, endogenous radiolabeling of 70-kDa protein was detected. An assay of the membranous fractions from 5 gastric adenocarcinomas with the extract of OMH4, a clinical H. pylori isolate, revealed notable radiolabelings of 55- and 45-kDa proteins, which were not found without the OMH4 extract. In contrast, the radiolabelings were minimal in the membranous fractions from respective non-tumorous mucosae, and they were not detected in any of the examined cytosolic fractions. All three radiolabelings of 70-, 55-, and 45-kDa proteins were dependent on NAD, but not on ADP-ribose. Snake venom phosphodiesterase digestion of the 3 radiolabeled proteins released only AMP. We thus found that H. pylori had an enzymatic mono-ADP-ribosyltransferase activity which enabled it to modify the 55- and 45-kDa membranous proteins of human gastric adenocarcinoma, as well as the 70-kDa protein of H. pylori itself. The possible roles underlying our observations on carcinogenesis or development of human gastric carcinoma are yet to be elucidated.
authors.affiliation: Department of Frontier Surgery, Chiba University Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Akai
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nabeya
authors.forename: Kinnosuke
authors.initials: K
authors.lastname: Yahiro
authors.forename: Naoko
authors.initials: N
authors.lastname: Morinaga
authors.forename: Kanae
authors.initials: K
authors.lastname: Mitsuhashi
authors.forename: Masahito
authors.initials: M
authors.lastname: Inoue
authors.forename: Akio
authors.initials: A
authors.lastname: Sakamoto
authors.forename: Takenori
authors.initials: T
authors.lastname: Ochiai
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Noda
mesh_terms: D036002:ADP Ribose Transferases / Q000302:isolation & purification / Q000378:metabolism*; D000230:Adenocarcinoma / Q000378:metabolism / Q000382:microbiology*; D000244:Adenosine Diphosphate / Q000378:metabolism*; D000368:Aged; D000369:Aged, 80 and over; D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism*; D005260:Female; D016480:Helicobacter pylori / Q000201:enzymology* / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D011499:Protein Processing, Post-Translational; D013274:Stomach Neoplasms / Q000378:metabolism / Q000382:microbiology*
chemical_list: D001426:Bacterial Proteins; D000244:Adenosine Diphosphate; D036002:ADP Ribose Transferases