People can think of their genome like a cook book. The instructions are your genetic code, and the finished products are proteins.
Like any recipe, ingredients can be tailored to change the outcome. Your epigenome is responsible for switching out ingredients without changing your genetic code. Epigenetic illness occurs when the epigenome operates incorrectly or is hijacked.
A scientist would say the field of epigenetics is the study of your epigenome, including the enzymes responsible for regulating the epigenome. Enzymes are proteins that use chemical reactions to modify DNA and other proteins. Epigenetic enzymes add or remove chemical groups to chromatin, the structural components of your chromosomes. The location and number of chemical groups on chromatin determine whether DNA is “closed”, meaning no gene expression, or “open”, meaning gene expression can begin. This is important because gene expression controls the type and number of proteins that can be found in a cell.
Epigenetic enzymes that remove chemicals are known as “erasers”, and those that add chemicals are known as “writers”.
Writers and erasers are always working to maintain a healthy equilibrium in gene expression patterns. They bind to DNA and work both to “open” and “close” DNA, and to interact with other proteins called transcription factors to initiate gene expression.
In cancer, writers and erasers can do their jobs either too much or too little. Just like too much salt can ruin a meal, the over expression of just one or a handful of proteins can create a tumor in the form of cancer. There is an intimate interplay between the genetic and epigenetic components of DNA, and both are sources of cancer. In the figure above, the top strand illustrates how genetic changes can give rise to cancer via mutations in genes. The bottom strand illustrates how epigenetic changes, proteins binding to DNA to change the way it is read, give rise to cancer via over- or underproduction of proteins. As we learn more about the ramifications of epigenetic changes in cancer pathology, it is becoming clear that targeting the epigenome is a viable strategy for the treatment and management of cancer.