title: Influence of Helicobacter pylori infection on the expression of MLH1 and MGMT in patients with chronic gastritis and gastric cancer.
abstract: The aim of the present study was to evaluate the influence of Helicobacter pylori on MLH1 and MGMT mRNA levels in patients with chronic gastritis and gastric cancer. The study included 217 patients, of which 26 were uninfected, 127 had chronic gastritis and were H. pylori-positive, and 64 had gastric cancer. Bacterial genotypes were evaluated by polymerase chain reaction (PCR), and the expression levels of MLH1 and MGMT were determined by quantitative real-time PCR and immunohistochemistry. There was an association between infection with cagA, vacA s1m1 strains and gastric cancer development. When the gastric epithelium and associated inflammation were examined for expression of MLH1 and MGMT, an overall increase in expression was observed. On the other hand, these levels decrease significantly among gastric cancer patients. The loss of MLH1 and MGMT expression in gastric cancer patients suggests that it is not an early event in H. pylori-associated gastric carcinogenesis.
authors.affiliation: Unidade Integrada de Farmacologia e Gastroenterologia, Universidade São Francisco, Av. São Francisco de Assis, 218. Jd. São José, Bragança Paulista, SP, Brazil.
authors.forename: W
authors.initials: W
authors.lastname: Bartchewsky
authors.forename: M R
authors.initials: MR
authors.lastname: Martini
authors.forename: A C
authors.initials: AC
authors.lastname: Squassoni
authors.forename: M C
authors.initials: MC
authors.lastname: Alvarez
authors.forename: M S P
authors.initials: MS
authors.lastname: Ladeira
authors.forename: D M F
authors.initials: DM
authors.lastname: Salvatore
authors.forename: M A
authors.initials: MA
authors.lastname: Trevisan
authors.forename: J
authors.initials: J
authors.lastname: Pedrazzoli
authors.forename: M L
authors.initials: ML
authors.lastname: Ribeiro
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015254:DNA Modification Methylases / Q000096:biosynthesis*; D045643:DNA Repair Enzymes / Q000096:biosynthesis*; D005260:Female; D005753:Gastric Mucosa / Q000382:microbiology / Q000473:pathology; D005756:Gastritis / Q000382:microbiology / Q000473:pathology*; D020869:Gene Expression Profiling; D016481:Helicobacter Infections / Q000382:microbiology / Q000473:pathology*; D016480:Helicobacter pylori / Q000302:isolation & purification*; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D009687:Nuclear Proteins / Q000096:biosynthesis*; D013274:Stomach Neoplasms / Q000382:microbiology / Q000473:pathology*; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis*; D055815:Young Adult
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D025521:Tumor Suppressor Proteins; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D000070957:MutL Protein Homolog 1; D045643:DNA Repair Enzymes