How do changes in the epigenome cause cancer?

Environmental factors and human behavior significantly contribute to cancer development. Factors such as unhealthy diet, sedentary lifestyle, drug use, and exposure to environmental toxins or radiation can induce epigenetic changes known as epimutations, which have the potential to promote cancer. For instance, smoking cigarettes over an extended period of years has been demonstrated to alter DNA methylation patterns throughout various organ systems, leading to lung cancer.

Altered patterns of histone modifications can affect chromatin structure, leading to aberrant gene expression. For instance, decreased histone acetylation and increased histone methylation in specific genes can promote cancer by inducing cell proliferation. In cancer, abnormal DNA methylation patterns can lead to the silencing of tumor suppressor genes or the activation of oncogenes. Noncoding RNAs (such as microRNAs and long noncoding RNAs) play critical roles in cancer by modulating the expression of genes involved in cellular processes that cause cancer. Additionally, dysregulation of chromatin remodeling in cancer can result in the activation of genes which promote cell proliferation.