title: E-cadherin promoter hypermethylation may contribute to protein inactivation in pterygia.
abstract: OBJECTIVE
  Our recent reports indicated that the molecular changes of pterygia are similar to tumor cells. We believe that pterygia may have a similar mechanism in oncogenesis. Many studies have revealed that E-cadherin associated protein expression decreases in many tumors and pterygia. E-cadherin may be a marker for both tumor metastasis and prognosis. However, no studies have examined the reason for E-cadherin protein inactivation in pterygia. Therefore, this study aimed to analyze the association of E-cadherin promoter hypermethylation with protein inactivation in pterygial tissues.
  
  
  METHODS
  E-cadherin methylation-status and the expression of E-cadherin and beta-catenin protein were studied using methylation-specific PCR and immunohistochemistry, respectively, on 120 pterygial specimens and 30 normal conjunctivas.
  
  
  RESULTS
  Hypermethylation of E-cadherin gene promoter was detected in 32 (26.7%) of the 120 pterygial specimens. A total of 79 (65.8%) pterygial specimens tested positive for E-cadherin protein expression and 41 (34.2%) specimens tested negative. The E-cadherin staining was limited to the membrane of the epithelial layer. There was a reverse correlation between E-cadherin gene promoter hypermethylation and E-cadherin protein expression (p<0.0001). Aberrant localization of beta-catenin was higher in the E-cadherin negative group than in E-cadherin positive group.
  
  
  CONCLUSIONS
  Our study demonstrates E-cadherin gene promoter hypermethylation were associated with low or absent expression of E-cadherin. Moreover, loss of E-cadherin protein may contribute to aberrant localization of beta-catenin. These data provide evidence that methylation exists in pterygia and may play a role in their development.
authors.affiliation: Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan.
authors.forename: Chi-Hsien
authors.initials: CH
authors.lastname: Young
authors.forename: Yu-Te
authors.initials: YT
authors.lastname: Chiu
authors.forename: Tung-Sheng
authors.initials: TS
authors.lastname: Shih
authors.forename: Wan-Ru
authors.initials: WR
authors.lastname: Lin
authors.forename: Chun-Chi
authors.initials: CC
authors.lastname: Chiang
authors.forename: Ying-Erh
authors.initials: YE
authors.lastname: Chou
authors.forename: Ya-Wen
authors.initials: YW
authors.lastname: Cheng
authors.forename: Yi-Yu
authors.initials: YY
authors.lastname: Tsai
mesh_terms: D000368:Aged; D015820:Cadherins / Q000235:genetics* / Q000378:metabolism*; D019175:DNA Methylation; D005260:Female; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D008875:Middle Aged; D011401:Promoter Regions, Genetic; D011625:Pterygium / Q000235:genetics* / Q000378:metabolism*; D013194:Staining and Labeling; D014018:Tissue Distribution; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D015820:Cadherins; D051176:beta Catenin