Background
Histones are basic proteins and are modified by diverse post-translation modifications such as acetylation, methylation, phosphorylation and ubiquitinylation. These epigenetic modifications are important regulatory processes in proliferation, survival, differentiation and motility. The epigenetic gene regulation occurs in DNA methylation at DNA level and histone modification or chromatin remodelling at protein level. Several enzymes, like DNA methyltransferases (DNMTs), histone methyltransferases (HMTs), histone demethylases (HDMs), histone acetyltransferases (HATs) and histone deacetylases (HDACs), are able to modify the chromatin. The histone modifications lead to alterations in chromatin and form heterochromatin or euchromatin, which activates or silences transcription. Statins are used successfully in the treatment of hypercholesterolemia and inhibit 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase. HMG-CoA reductase is the rate-limiting enzyme of the mevalonate pathway. The synthesis of isoprenoids such as farnesylpyrophosphate (FPP) and geranylgeranylpyrophosphate (GGPP) is reduced by statins by inhibition of the HMG-CoA reductase. These isoprenoid intermediates are involved in post-translational modifications of Ras, Rho and Rac, which are typical for G proteins and have crucial roles in cancer cells.