title: Aberrant methylation of secreted frizzled-related protein genes in esophageal adenocarcinoma and Barrett's esophagus.
abstract: Hypermethylation of secreted frizzled-related proteins (SFRP) genes frequently occurs with several cancers but has not been studied in esophageal adenocarcinoma or its precursor-Barrett's esophagus. To explore the role of SFRP methylation in the neoplastic progression of Barrett's esophagus and to evaluate methylated SFRP genes as biomarkers for Barrett's esophagus and cancer, methylation of SFRP genes was determined in esophageal adenocarcinomas, Barrett's esophagus and normal epithelia using methylation-specific PCR. Protein expression of SFRP genes was then assessed in these tissues by immunohistochemistry. The mRNA expression of SFRP genes was quantified by real-time reverse-transcription PCR in esophageal adenocarcinoma cell lines with and without demethylation by 5-aza-2'deoxycytidine and inhibition of deacetylation by trichostatin A treatment. Hypermethylation of SFRP1, 2, 4 and 5 was detected in 93%, 83%, 73% and 85% of 40 cancers; 81%, 89%, 78% and 73% of 37 Barrett's epithelia; 25%, 64%, 32% and 21% of 28 adjacent normal epithelia from Barrett's patients; and 10%, 67%, 0% and 13% of 30 normal esophagogastric epithelia from healthy individuals, respectively (p < 0.001 for SFRP1, 4 and 5; p < 0.05 for SFRP2). Protein expression of SFRP1, 2 and 4 was downregulated in 87%, 67% and 90% of cancers, and expression correlated inversely with grade and stage of cancers and with grade of dysplasia. Expression of SFRP2 and SFRP4 proteins was lower in cancers with corresponding gene methylation (p < 0.05). Demethylation treatment effectively re-expressed SFRP mRNA in cancer cell lines. Thus, hypermethylation of SFRP genes is a common early event in the evolution of esophageal adenocarcinoma, and methylation of SFRP1, 4 and 5 might serve as biomarkers for Barrett's neoplasia. Aberrant promoter methylation appears to functionally silence SFRP gene expression in esophageal adenocarcinoma.
authors.affiliation: Department of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: Hongzhi
authors.initials: H
authors.lastname: Zou
authors.forename: Julian R
authors.initials: JR
authors.lastname: Molina
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Harrington
authors.forename: Neal K
authors.initials: NK
authors.lastname: Osborn
authors.forename: Kristie K
authors.initials: KK
authors.lastname: Klatt
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Romero
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Burgart
authors.forename: David A
authors.initials: DA
authors.lastname: Ahlquist
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001471:Barrett Esophagus / Q000235:genetics* / Q000473:pathology*; D014408:Biomarkers, Tumor / Q000032:analysis; D016022:Case-Control Studies; D002471:Cell Transformation, Neoplastic; D019175:DNA Methylation; D018450:Disease Progression; D004938:Esophageal Neoplasms / Q000235:genetics* / Q000473:pathology*; D005136:Eye Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D020868:Gene Silencing; D006801:Humans; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D008875:Middle Aged; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D000094742:Secreted Frizzled-Related Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D014408:Biomarkers, Tumor; D005136:Eye Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; C117636:SFRP1 protein, human; D000094742:Secreted Frizzled-Related Proteins; C118723:SFRP4 protein, human; C118511:SFRP5 protein, human