The Aberrant Imprinting Of IGF2/H19 And The Methylation Status Of The Differentially Methylated Region Upstream Of H19 In Human Hepatocellular Carcinoma

[Background and Objective] Genomic imprinting is the preferential silencing of one parental allele due to epigenetic modifications. Insulin-like growth factor 2 (IGF2) and H19 are two imprinted genes located adjacent to each other at chromosome 11p15.5 in humans. IGF2, which encodes a protein functioning as a fetal growth factor and a cell mitogen, is expressed only from paternally allele in most tissues but from both alleles in adult liver. H1 9, which acts as an RNA, is a gene of unknown function and expressed only from maternally allele. Abnormal imprinting of IGF2 and/or H19, including gain of imprinting (GOI) and loss of imprinting (LOI), commonly occurs in various types of cancer, and may be involved in malignant transformation. The mechanisms for GOI and LOI are not elucidated. A large number of studies were focused upon the modification of the differentially methylated regions (DMRs).Although the aberrant imprinting of IGF2 and H19 has been observed many years ago, there are few reports focused upon the mechanism of...