title: Effect of promoter methylation of multidrug resistance 1 (MDR1) gene in gastric carcinogenesis.
abstract: BACKGROUND
  The altered expression of multidrug resistance 1 (MDR1) contributes to various types of carcinogenesis and their disease progression. Hypermethylation of CpG islands located in the promoter regions is involved in gene silencing at the transcriptional level. The methylation status of MDR1 gene promoter was investigated in gastric cancer in relation to various clinicopathological features.
  
  
  METHODS
  The methylation of the MDR1 promoter was estimated in both antral non-neoplastic mucosa and cancer lesions in 83 patients with gastric cancer using a methylation-specific PCR method.
  
  
  RESULTS
  The methylation ratio (MR) of the cancer lesions (31.3 +/- 20.5) was significantly higher than that of non non-neoplastic mucosa (20.9 +/- 31.3, p = 0.0004). The MR was especially high in Lauren's intestinal cancer (p < 0.0001). A higher MR was also observed in more advanced stage (p = 0.005) and lymph vessel invasion-positive cases (p = 0.002).
  
  
  CONCLUSIONS
  The promoter methylation of MDR1 seems to have a significant role in carcinogenesis and tumor progression in the stomach.
authors.affiliation: Department of Gastroenterology, Fujita Health University School of Medicine, Toyoake, Japan. tomomiccyu@yahoo.co.jp
authors.forename: Tomomitsu
authors.initials: T
authors.lastname: Tahara
authors.forename: Tomiyasu
authors.initials: T
authors.lastname: Arisawa
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Shibata
authors.forename: Hiromi
authors.initials: H
authors.lastname: Yamashita
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yoshioka
authors.forename: Ichiro
authors.initials: I
authors.lastname: Hirata