Aberrant methylation of secreted frizzled‐related protein genes in esophageal adenocarcinoma and Barrett's esophagus

<jats:title>Abstract</jats:title><jats:p>Hypermethylation of secreted frizzled‐related proteins (<jats:italic>SFRP</jats:italic>) 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 <jats:italic>SFRP</jats:italic> methylation in the neoplastic progression of Barrett's esophagus and to evaluate methylated <jats:italic>SFRP</jats:italic> genes as biomarkers for Barrett's esophagus and cancer, methylation of <jats:italic>SFRP</jats:italic> genes was determined in esophageal adenocarcinomas, Barrett's esophagus and normal epithelia using methylation‐specific PCR. Protein expression of <jats:italic>SFRP</jats:italic> genes was then assessed in these tissues by immunohistochemistry. The mRNA expression of <jats:italic>SFRP</jats:italic> 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 <jats:italic>SFRP1, 2, 4</jats:italic> and <jats:italic>5</jats:italic> 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 (<jats:italic>p</jats:italic> < 0.001 for <jats:italic>SFRP1, 4</jats:italic> and <jats:italic>5</jats:italic>; <jats:italic>p</jats:italic> < 0.05 for <jats:italic>SFRP2</jats:italic>). Protein expression of <jats:italic>SFRP1, 2</jats:italic> and <jats:italic>4</jats:italic> 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 (<jats:italic>p</jats:italic> < 0.05). Demethylation treatment effectively re‐expressed <jats:italic>SFRP</jats:italic> mRNA in cancer cell lines. Thus, hypermethylation of <jats:italic>SFRP</jats:italic> genes is a common early event in the evolution of esophageal adenocarcinoma, and methylation of <jats:italic>SFRP1, 4</jats:italic> and <jats:italic>5</jats:italic> might serve as biomarkers for Barrett's neoplasia. Aberrant promoter methylation appears to functionally silence <jats:italic>SFRP</jats:italic> gene expression in esophageal adenocarcinoma. © 2005 Wiley‐Liss, Inc.</jats:p>