In this chapter, we focused on epigenetic modifications to the genome that regulate gene expression. Several mechanisms are involved, and epigenetic control of gene expression is important in development, cancer, and modulating the genomic response to environmental factors. From the explanations given in the chapter,

What is the evidence that epigenetic changes are involved in cancer?

Key Concepts

Epigenetics

Epigenetics refers to the study of heritable changes in gene expression that do not involve alterations to the underlying DNA sequence. These changes can be influenced by various factors, including environmental stimuli, and can affect how genes are turned on or off. Common epigenetic modifications include DNA methylation and histone modification, which play crucial roles in regulating gene activity.

DNA Methylation

DNA methylation is a key epigenetic mechanism where methyl groups are added to the DNA molecule, typically at cytosine bases. This modification can repress gene expression by preventing the binding of transcription factors and other necessary proteins. Abnormal patterns of DNA methylation are often observed in cancer cells, leading to the silencing of tumor suppressor genes and contributing to tumorigenesis.

Histone Modification

Histone modification involves the addition or removal of chemical groups to histone proteins around which DNA is wrapped. These modifications, such as acetylation and phosphorylation, can alter the structure of chromatin, making it more or less accessible for transcription. In cancer, specific histone modifications can lead to the activation of oncogenes or the silencing of genes that normally suppress tumor growth, thereby influencing cancer progression.