Correlation of hMLH1 and HPP1 hypermethylation in gastric, but not in esophageal and cardiac adenocarcinoma

Abstract

Deregulated epigenetic mechanisms are likely involved in the pathogenesis of myelodysplastic syndromes (MDSs). Which genes are silenced by aberrant promotor methylation during MDS hematopoiesis has not been equivalently investigated. Using an in vitro differentiation model of human hematopoiesis, we generated defined differentiation stages (day 0, day 4, day 7, day 11) of erythro-, thrombo- and granulopoiesis from 13 MDS patients and seven healthy donors. Promotor methylation analysis of key regulatory genes involved in cell cycle control (p14, p15, p16, CHK2), DNA repair (hMLH1), apoptosis (p73, survivin, DAPK), and differentiation (RARb, WT1) was performed by methylation-specific polymerase chain reaction. Corresponding gene expression was analyzed by microarray (Affymetrix, HG-U133A). We provide evidence that p16, survivin, CHK2, and WT1 are affected by promotor hypermethylation in MDSs displaying a selective International Prognostic Scoring System risk association. A methylation-associated mRNA downregulation for specific hematopoietic lineages and differentiation stages is demonstrated for survivin, CHK2, and WT1. We identified a suppressed survivin mRNA expression in methylated samples during erythropoiesis, whereas WT1 and CHK2 methylation-related reduction of mRNA expression was found during granulopoiesis in all MDS risk types. Our data suggest that lineage-specific methylation-associated gene silencing of survivin, CHK2, and WT1 in MDS hematopoietic precursor cells may contribute to the MDS-specific phenotype.