title: Reprimo as a potential biomarker for early detection in gastric cancer.
abstract: OBJECTIVE
  Gastric cancer is a curable disease if diagnosed at early stage. However, most cases are diagnosed at advanced stage because of the lack of screening programs. Therefore, the identification of plasma biomarkers for early detection is necessary.
  
  
  METHODS
  To search for these biomarkers, we evaluated the DNA methylation patterns of 24 genes by Methylation-specific PCR in primary tissues from 32 retrospectively collected gastric cancer cases (testing group). Correlation between methylation and gene expression was evaluated in the MKN-45 cell line after treatment with 5-aza-2'-deoxycytidine. The most frequently hypermethylated genes were next evaluated in primary tissues and plasma samples from 43 prospectively collected gastric cancer cases as well as plasma samples from 31 asymptomatic age- and gender-matched controls (validation group).
  
  
  RESULTS
  In the testing group, 11 genes were hypermethylated in at least 50% of cases (APC, SHP1, E-cadherin, ER, Reprimo, SEMA3B, 3OST2, p14, p15, DAPK, and p16). Eight genes (BRCA1, p73, RARbeta, hMLH1, RIZI, RUNX3, MGMT, and TIMP3) were statistically associated with a particular variant of gastric cancer, the signet-ring cell type (P = 0.03). Seven genes (APC, SHP1, E-cadherin, ER, Reprimo, SEMA3B, and 3OST2) were next evaluated in the validation group. We confirm the high frequency of methylation in primary tumors for all seven genes. However, only APC and Reprimo were frequently methylated in pair plasma samples. In asymptomatic controls, only Reprimo was infrequently methylated in comparison with plasma from gastric cancer cases (P < 0.001).
  
  
  CONCLUSIONS
  Our results identified specific methylation profile associated to signet-ring cell-type histology and aberrant hypermethylation of Reprimo as a potential biomarker for early detection of gastric cancer.
authors.affiliation: Department of Anatomic Pathology, Centro Investigaciones Medicas, Pontificia Universidad Católica de Chile, Santiago, Chile.
authors.forename: Carolina
authors.initials: C
authors.lastname: Bernal
authors.forename: Francisco
authors.initials: F
authors.lastname: Aguayo
authors.forename: Cynthia
authors.initials: C
authors.lastname: Villarroel
authors.forename: Macarena
authors.initials: M
authors.lastname: Vargas
authors.forename: Ignacio
authors.initials: I
authors.lastname: Díaz
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Ossandon
authors.forename: Eudocia
authors.initials: E
authors.lastname: Santibáñez
authors.forename: Mariana
authors.initials: M
authors.lastname: Palma
authors.forename: Edmundo
authors.initials: E
authors.lastname: Aravena
authors.forename: Carlos
authors.initials: C
authors.lastname: Barrientos
authors.forename: Alejandro H
authors.initials: AH
authors.lastname: Corvalan
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D018279:Carcinoma, Signet Ring Cell / Q000097:blood / Q000175:diagnosis* / Q000473:pathology; D018797:Cell Cycle Proteins / Q000097:blood* / Q000235:genetics*; D045744:Cell Line, Tumor; D018899:CpG Islands; D019175:DNA Methylation; D005260:Female; D006023:Glycoproteins / Q000097:blood* / Q000235:genetics*; D006801:Humans; D008297:Male; D008745:Methylation; D008875:Middle Aged; D008954:Models, Biological; D016133:Polymerase Chain Reaction; D013274:Stomach Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D006023:Glycoproteins; C412566:RPRM protein, human