Chapter 19 - Epigenetics in diagnosis, prognosis and therapy: therapies targeting the epigenome

Abstract

Derived from a Greek prefix, epi (ἐπι- “in annexation, on the top of, all over”) in “Epigenetics” refers to some specific characteristics which are either on “the outside” or “in annexation” to the genetic basis of inheritance. It is a novel field in molecular biochemistry revolving around the study of altered heritable phenotype(s), changes affecting the gene expression (GE) and gene activity, without changes in the DNA sequence. These alterations on phenotypic characteristics often resulting from environmental factors or can be a part of natural growth and development. Some of the epigenetic mechanisms such as – DNA methylation and histone modifications, etc., have been found to directly affect the gene expression (GE) without changing the DNA sequence. Oncogenic cells are composed of myriad epigenetic alterations. With the advent of genome-wide associated (GWAS) approaches, a better understanding of such epigenetic changes in cancer has developed. There are many genes along with their relevant pathways which highlight epigenetic alterations between a normal and tumor cell and showcase the pivotal role of epigenetic factors in cancer biology and progression. Furthermore, it has also allowed the determination of diagnostic, prognostic and personalized therapies for a wide range of neoplasms and reproductive disorders. Epigenetic drugs have been employed for cancer and have been widely appreciated by consultants and patients because of their high efficiency and robustness. This chapter highlights current status of the development and application of epigenetic approaches for the diagnosis, prognosis and treatment of cancer (pharmacoepigenetics) and reproductive disorders. Also, the chapter provides a glimpse of original epigenetic research for identification of epigenetic biomarkers associated with cancer diagnosis and disease progression.