Review-Epigenetic therapy for cancer.

Epigenetics means the study of alterations in the genetic material that affect the phenotype but does not affect the genotype. Epigenetics cause alterations in cell properties, which are inherited; but it does not cause alterations in DNA sequence. Epigenetic mediated silencing of gene is of four types, which are DNA methylation, histone deacetylation, RNA associated silencing and Genomic imprinting. Other factors (environmental and xenobiotics) can also cause gene silencing but DNA methytlation and changes in histones of chromatin are two important changes, which are responsible for malignant diseases. Two groups of drugs are under development, which corrects the epigenetic alterations. These are histone deacetylation (HDAC) inhibitors and DNA methytransferase (DNMT) inhibitors. These drugs may be used in cancer because in cancer, hypermethylation of cancer suppressor gene causes gene silencing. Epigenetic therapy scope is likely to increase in future.