Epigenomics and epigenetics involve study of the epigenome. The epigenome is a full record of the changes to the protein and DNA of an organism. Epigenetics focuses on the processes that regulate how and when specific genes are turned off and on. Epigenomics looks at the genome as a whole, analyzing changes to many genes within the cell, or sometimes the organism itself.
Changes to the epigenome can cause anomalies in the structure and function of the genome. These changes can be passed on via transgenerational epigenetic inheritance, causing disorders that have the potential to affect future generations.
The epigenome is responsible for a number of functions, including gene expression, gene development, tissue differentiation, and the suppression of transposable elements. Unlike the genome itself, which is largely static, the epigenome is susceptible to environmental conditions and can be drastically altered by them.
The epigenome can alter DNA in two different ways, both of which play a role in turning genes on or off. The first happens when chemical tags known as methyl groups attach themselves to a DNA molecule. The second happens when a mix of chemical tags attach themselves to the tails of histones—the spool-like proteins that wrap DNA so efficiently into chromosomes. These tags affect how tightly DNA is wrapped around the histones.
Epigenomics and Cancer
Since the inception of genomics, the medical world has recognized that the huge amount of data that has been generated has the potential to be applied to the fight against cancer. Since the 1980s, scientists have been experimenting with the administration of drugs at a genomic level in order to treat cancer and other diseases. Over the past 10 years, there has been a dramatic increase in the development of drugs aimed at affecting epigenetic mechanisms.
It is currently hypothesized that the underlying cause of cancer is DNA damage. If the DNA’s repair mechanisms are deficient, DNA damage can accumulate. DNA damage can cause further epigenetic alterations through errors in DNA repair. These epigenetic alterations can cause growth of abnormal tissue, resulting in a cancerous tumor.
Epigenomics and epigenetics play important roles in cancer epidemiology. This area of scientific inquiry has provided a great deal of insight into gene regulation and facilitated cancer control. Experts in cancer research are increasingly using epigenetic analysis in their studies of disease etiology and outcomes.
Cancer can manifest in patients who are predisposed to the disease by a genetic mutation. Four major epigenetic mechanisms (namely histone modification, nucleosome remodeling, DNA methylation and microRNAs) control gene activity. These genomic processes have been shown to play a key role in the development of a number of complex diseases, including cancer.
Research has indicated a particularly strong link between anomalies in DNA methylation and breast, lung, esophageal, pancreatic, ovarian, prostate, colon, and other cancers. Epigenetics has been demonstrated to compromise the stability of the genome and gene expression. Epigenetic anomalies influence carcinogenesis from initiation through progression, sometimes throughout a person’s lifespan, with the potential for faulty gene expression to be passed down to subsequent generations.
Epigenetic events relevant to cancer risk are thought to occur in the initial stages of cancer development, thus serving as potential triggers in tumorigenesis. Epigenetic markers reflect both a person’s genetic background as well as his or her exposure to various environmental factors, thus increasing scientists’ understanding of the role played by environmental exposure in carcinogenesis. Since epigenetic changes occur before or early on in development of a tumor, they can more easily be modulated by drugs.
Epigenomics and Breast Cancer
Epigenomics has been key to a recent breast cancer study at the Imperial College, London. A team of experts has been using breast cancer models in order to demonstrate how epigenetic reprogramming of chromatic information promotes the expression of genes related to resistance to endocrine therapies.
The study has created epigenomic maps enabling the study of the regulatory network of cancer cells and how these networks respond to particular therapies. The aim of the initiative is to exploit epigenetic mapping in order to identify biomarkers and drug-responsive targets. It is in this way that the Imperial College hope to develop new compounds designed to interfere with reprogramming.
Epigenomics and Cancer Screening by Blood Test
With the help of epigenomics, it is hoped that just a few years from now, a simple blood test will reveal whether a person has liver cancer. Findings were recently published from two clinical studies demonstrating the high accuracy of biomarker mSEPT9 in identifying liver cancer amongst individuals with cirrhosis.
It is hoped that this breakthrough will one day lead to the availability of blood tests that diagnose a wide variety of cancer types. However, the World Health Organization notes that liver cancer is the seventh-most common cancer in women and the fifth-most common in men, ranking second in cancer mortality worldwide with 700,000 people being diagnosed annually. As a result, this innovation already represents a significant achievement in itself, with the potential to save many lives.