Epigenetic modifications in cancer

Cancer initiation and progression is controlled by both genetic and epigenetic events. The complexity of carcinogenesis cannot be accounted for by genetic alterations alone but also involves epigenetic changes. Epigenetics refers to the study of mechanisms that alter gene expression without altering the primary DNA sequence. Epigenetic mechanisms are heritable and reversible, and include changes in DNA methylation, histone modifications and small noncoding microRNAs (miRNA). Disruption of epigenetic processes can lead to altered gene function and malignant cellular transformation. Aberrant epigenetic modifications probably occur at a very early stage in neoplastic development, and they are widely described as essential players in cancer progression. Recent advances in epigenetics offer a better understanding of the underlying mechanism(s) of carcinogenesis and provide insight into the discovery of putative cancer biomarkers for early detection, disease monitoring, prognosis, and risk assessment. In this review, we summarize the current literature on epigenetic changes causing genetic alterations that are thought to contribute to cancer, and discuss the potential impact of epigenetics future research.