Mechanism of cancer: Oncohistones in action.

Oncohistones are histones with high-frequency point mutations that are associated with tumorigenesis. Although each histone variant is encoded by multiple genes, a single mutation in one allele of one gene seems to have a dominant effect over global histone H3 methylation level at the relevant amino acid residue. These oncohistones are highly tumor type specific. For example, H3K27M and H3G34V/R mutations occur only in pediatric brain cancers, whereas H3K36M and H3G34W/L have only been found in pediatric bone tumors. H1 mutations also seem to be exclusively linked to lymphomas. In this review, we discuss the occurrence, frequency and potential functional mechanisms of each oncohistone in tumorigenesis of its relevant cancer. We believe that further investigation into the mechanism regarding their tumor type specificity and cancer-related functions will shed new light on their application in cancer diagnosis and targeted therapy development.