[Methylation and other new concepts for the origin of hepatocellular carcinoma].

Methylation takes place when a methyl group, comprised of a carbon and three hydrogen atoms (CH3), attaches to the individual DNA bases. This modification of the DNA leads to a change in gene expression. Changes in the methylation status of the DNA belong to the most common gene changes leading to malignant tumours. Recent studies have shown that three different mechanisms play a role in the effect of methylation: global hypomethylation, hypermethylation of individual gene segments and the deregulated expression of DNA methyltransferases. Such DNA methylation is also one of the most homogenous and consistent molecular changes in hepatocellular carcinoma (HCC). Moreover, the hypermethylation of specific genes has been shown to precede the development of malignant tumours. Thus, DNA methylation is a possible biomarker for the early discovery of HCC. The reversibility of methylation also offers a possible future treatment option.