Epigenetics in disease and cancer.

Since the discovery of the double-helical structure of DNA, genetic regulation of gene expression has been well elucidated. More recently, another equally, if not more, important scheme of regulation of gene expression, called epigenetics, has emerged to explain the many biological observations that traditional genetic mechanisms have failed to decipher. Epigenetics is a discipline of study on the biological consequences of cellular alterations that do not involve nucleotide changes, as opposed to genetic mutations. Epigenetic changes are reversible and may lead to loss or gain of biological functions. The three most reported mechanisms of epigenetic regulation of gene expression involve changes in: (i) chromatin remodelling, (ii) DNA methylation and (iii) microRNA (miRNA). More importantly, many of the elucidated epigenetic changes are linked to the pathogenesis of human diseases and cancers. In this mini review, core concepts and basic experimental approaches in the study of epigenetic regulation of gene expression are briefly reviewed in relation to disease, with emphasis on cancer. This mini review also intends to highlight the fact that, besides genetics, epigenetics is now a discipline physicians and clinical research scientists can no longer ignore in their pursuit to understand disease and cancer and to develop new therapeutic strategies for treatment.