CBP mediated DOT1L acetylation confers DOT1L stability and promotes cancer metastasis

Abstract

Background and Aim: DOT1L regulates various genes involved in cancer onset and progression by catalyzing H3K79 methylation, but how DOT1L activity itself is regulated is unclear. Here, we aimed to identify specific DOT1L post-translational modifications that might regulate DOT1L activity and thus impact on colorectal cancer (CRC) progression. Methods: We conducted affinity purification and mass spectrometry to explore DOT1L post-translational modifications. We then established transwell migration and invasion assays to specifically investigate the role of DOT1L(K358) acetylation on CRC cellular behavior in vitro and a bioluminescence imaging approach to determine the role of DOT1L(K358) acetylation in CRC metastasis in vivo. We performed chromatin immunoprecipitation to identify DOT1L acetylation-controlled target genes. Finally, we used immunohistochemical staining of human tissue arrays to examine the relevance of DOT1L(K358) acetylation in CRC progression and metastasis and the correlation between DOT1L acetylation and CBP. Results: We found that CBP mediates DOT1L K358 acetylation in human colon cancer cells and positively correlates with CRC stages. Mechanistically, DOT1L acetylation confers DOT1L stability by preventing the binding of RNF8 to DOT1L and subsequent proteasomal degradation, but does not affect its enzyme activity. Once stabilized, DOT1L can catalyze the H3K79 methylation of genes involved in epithelial–mesenchymal transition, including SNAIL and ZEB1. An acetylation mimic DOT1L mutant (Q358) could induce a cancer-like phenotype in vitro, characterized by metastasis and invasion. Finally, DOT1L(K358) acetylation correlated with CRC progression and a poor survival rate as well as with high CBP expression. Conclusions: DOT1L acetylation by CBP drives CRC progression and metastasis. Targeting DOT1L deacetylation signaling is a potential therapeutic strategy for DOT1L-driven cancers.