Promoter-specific methylation and expression alterations of igf2 and h19 are involved in human hepatoblastoma.

In earlier studies we found up-regulation of promoter P3 transcription and total igf2 expression with concomitant down-regulation of h19 expression in human hepatoblastoma (HB). In this study, we investigated the methylation status of these 2 genes and their abnormal regulation in 7 hepatoblastomas and 5 normal counterpart tissues. A specific part of the P3 region of igf2 was de-methylated in tumors with up-regulation of the promoter activity. A site-specific DNA hypermethylation in the h19 5'-region was found in tumor tissues with concomitant down-regulation of this gene. Therefore, abnormal methylation was found to be correlated with altered regulation of igf2 and h19 expression in human hepatoblastoma and may be involved in the genesis of this tumor.