title: Polymorphism of A133S and promoter hypermethylation in Ras association domain family 1A gene (RASSF1A) is associated with risk of esophageal and gastric cardia cancers in Chinese population from high incidence area in northern China.
abstract: BACKGROUND
  The role of tumor suppressor gene RASSF1A in the esophageal and gastric cardia carcinogenesis is still inconclusive. In this study, the polymorphism, promoter methylation and gene expression of RASSF1A were characterized in esophageal squamous cell carcinoma (ESCC) and gastric cardia adenocarcinoma (GCA).
  
  
  METHODS
  We firstly analyzed the prevalence of RASSF1A A133S in a total of 228 cancer patients with ESCC (n=112) and GCA (n=116) and 235 normal controls by polymerase chain reaction (PCR) and restriction enzyme-digestion assay. Then, the promoter methylation status of the RASSF1A in ESCC (n=143), GCA (n=92) and corresponding adjacent normal tissues were further investigated using methylation-specific PCR (MSP) approach. Finally, the RASSF1A protein expression were determined in ESCC (n=27), GCA (n=24) and the matched adjacent normal tissues by immunohistochemical method.
  
  
  RESULTS
  The frequency of 133Ala/Se and Ser/Ser genotype was significantly higher in GCA patients than in normal controls (19.0% vs. 10.2%, P=0.02). Compared with Ala/Ala genotype, Ala/Se and Ser/Ser genotype significantly increased susceptibility to GCA (OR=2.06, 95% CI=1.09-3.97). However, this polymorphism had no association with ESCC (P=0.69). The promoter methylation of RASSF1A gene was significantly increased the risk to both ESCC (OR=5.90, 95% CI=2.78-12.52) and GCA (OR=7.50, 95% CI= 2.78-20.23). Promoter methylation of RASSF1A gene in ESCC was also associated with age and cancer cell differentiation (for age: OR=3.11, 95% CI=1.10-8.73; for differentiation: OR=0.29, 95% CI=0.12-0.69). RASSF1A positive expression was significantly decreased the risk of GCA (OR=0.16, 95% CI=0.03-0.83). In contrast, there was no statistical significance between RASSF1A positive expression and ESCC. The expression of RASSF1A protein trend to be positively related with older GCA patients (OR=16.20, 95% CI=1.57-167.74).
  
  
  CONCLUSIONS
  The present findings suggest that alterations of RASSF1A may play an important role in gastric cardia carcinogenesis in terms of polymorphism, promoter hypermethylation and protein expression. Whereas, RASSF1A hypermethylation may probably also be involved in esophageal squamous cell carcinogenesis.
authors.affiliation: Henan Key Laboratory for Esophageal Cancer Research, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China.
authors.forename: Sheng Li
authors.initials: SL
authors.lastname: Zhou
authors.forename: Juan
authors.initials: J
authors.lastname: Cui
authors.forename: Zong Min
authors.initials: ZM
authors.lastname: Fan
authors.forename: Xue Min
authors.initials: XM
authors.lastname: Li
authors.forename: Ji Lin
authors.initials: JL
authors.lastname: Li
authors.forename: Bao Chi
authors.initials: BC
authors.lastname: Liu
authors.forename: Dong Yun
authors.initials: DY
authors.lastname: Zhang
authors.forename: Hong Yan
authors.initials: HY
authors.lastname: Liu
authors.forename: Xue Ke
authors.initials: XK
authors.lastname: Zhao
authors.forename: Xin
authors.initials: X
authors.lastname: Song
authors.forename: Ran
authors.initials: R
authors.lastname: Wang
authors.forename: Ze Chen
authors.initials: ZC
authors.lastname: Yan
authors.forename: Hui Xing
authors.initials: HX
authors.lastname: Yi
authors.forename: Li Dong
authors.initials: LD
authors.lastname: Wang
mesh_terms: D000230:Adenocarcinoma / Q000453:epidemiology / Q000235:genetics*; D002294:Carcinoma, Squamous Cell / Q000453:epidemiology / Q000235:genetics*; D002299:Cardia / Q000473:pathology; D002681:China / Q000453:epidemiology; D019175:DNA Methylation / Q000235:genetics; D004938:Esophageal Neoplasms / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005838:Genotype; D006801:Humans; D007150:Immunohistochemistry; D015994:Incidence; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000453:epidemiology / Q000235:genetics*; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: C411762:RASSF1 protein, human; D025521:Tumor Suppressor Proteins