title: Hypermethylation of TGF-β1 gene promoter in gastric cancer.
abstract: OBJECTIVE
  To examine transforming growth factor-β1 (TGF-β1) promoter methylation in gastric cancer and to determine if Helicobacter pylori (H. pylori) or interleukin (IL)-1β could induce TGF-β1 hypermethylation in vitro.
  
  
  METHODS
  We examined the frequency and extent of TGF-β1 promoter methylation using methylation-specific PCR in the gastric tissues from 47 gastric cancer patients and 39 non-gastric cancer subjects. H. pylori infection was confirmed by a positive result from either a serological test, histological analysis or C¹³ urea breath test. GES-1 and MKN-45 cells co-cultured with H. pylori or treated with IL-1β for 12, 24 and 48 h in vitro tested the effects of H. pylori or IL-1β on TGF-β1.
  
  
  RESULTS
  Twenty-four/forty-seven (51%) cases of gastric cancer (GC) tissues showed TGF-β1 promoter methylation, 15/47 (31.9%) cases of matched non-cancerous gastric mucosa tissues from the GC patients, and 11/39 (28%) case of the normal gastric mucosa tissues from non-GC subjects showed TGF-β1 promoter methylation (51% vs 28%, P < 0.05). Significantly higher levels of methylation of TGF-β1 were found in the tumor tissues than in non-tumor tissues from GC patients (0.24 ± 0.06 vs 0.17 ± 0.04, P < 0.05) and normal gastric tissues from non-GC subjects (0.24 ± 0.06 vs 0.15 ± 0.03, P < 0.05). TGF-β1 methylation was found in 48.3% of H. pylori-positive gastric mucosal tissues whereas only 23.1% of H. pylori-negative gastric mucosal tissues showed TGF-β1 methylation (48.3% vs 23.1%, P < 0.05). IL-1β appeared to induce a dose-dependent methylation of TGF-β1 and the strongest methylation was observed in GES-1 cells treated with 2.5 ng/mL of IL-1β for 48 h. Further studies showed that pre-treatment of GES-1 cells with 20 ng/mL IL-1RA for 1 h could partially abolish the effect of IL-1β on TGF-β1 methylation. Infection of GES-1 cells by H. pylori was not found to induce significant TGF-β1 promoter methylation.
  
  
  CONCLUSIONS
  Our data revealed that TGF-β1 promoter is methylated in GC patients. IL-1β may be an important mediator for H. pylori induced gene methylation during GC development.
authors.affiliation: Yong-Qi Wang, Yu-Min Li, School of Life Sciences, Lanzhou University, Lanzhou 730000, Gansu Province, China.
authors.forename: Yong-Qi
authors.initials: YQ
authors.lastname: Wang
authors.forename: Yu-Min
authors.initials: YM
authors.lastname: Li
authors.forename: Xun
authors.initials: X
authors.lastname: Li
authors.forename: Tao
authors.initials: T
authors.lastname: Liu
authors.forename: Xiao-Kang
authors.initials: XK
authors.lastname: Liu
authors.forename: Jun-Qiang
authors.initials: JQ
authors.lastname: Zhang
authors.forename: Ju-Wu
authors.initials: JW
authors.lastname: Guo
authors.forename: Ling-Yun
authors.initials: LY
authors.lastname: Guo
authors.forename: Liang
authors.initials: L
authors.lastname: Qiao
mesh_terms: D016022:Case-Control Studies; D002460:Cell Line; D019175:DNA Methylation; D005260:Female; D016480:Helicobacter pylori / Q000502:physiology*; D054884:Host-Pathogen Interactions; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism / Q000502:physiology; D008297:Male; D008875:Middle Aged; D011401:Promoter Regions, Genetic; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism*
chemical_list: C508585:IL1B protein, human; D053583:Interleukin-1beta; C508960:TGFB1 protein, human; D053773:Transforming Growth Factor beta1
keywords: Gastric cancer; Helicobacter pylori; Interleukin-1β; Methylation; Transforming growth factor-β1
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