Figure 4. Age-related epigenetic changes and their effects on tumorigenesis.
(A-D) Aging is characterized by multiple alterations in the epigenome including (A) loss of histones and heterochromatin, (B) an increased frequency of non-canonical, variant histones, (C) a change in the balance of activating and repressing histone modifications, and (D) global DNA hypomethylation among others. These changes have been implicated in tumor growth and progression through the alteration of gene expression, genomic instability, and an increase in immune checkpoint molecule expression in cancer cells (inset box).