Activation of AKT induces EZH2-mediated β-catenin trimethylation in colorectal cancer. [ChIP-Seq]

The lysine methyltransferase EZH2 is overexpressed in colorectal cancer (CRC) and has been found to be positively and negatively correlated with CRC patient survival depending on the study suggesting that EZH2 has a complex role in CRC. Here, we demonstrate that AKT-mediated EZH2 S21 phosphorylation induced EZH2 to trimethylate β-catenin at K49, which increased β-catenin’s binding to the chromatin. Additionally, EZH2-mediated β-catenin trimethylation induced β-catenin’s interaction with TCF1 and RNA polymerase II and resulted in a dramatic gain in genomic regions with β-catenin occupancy. Interestingly, EZH2 catalytic inhibition decreased stemness but increased migratory phenotypes of CRC cells with active AKT. Overall, we demonstrated that EZH2 modulates AKT-induced changes in gene expression through the AKT/EZH2/β-catenin axis in CRC. Our results suggest that EZH2 inhibitors have tumor-inhibiting and promoting effects in CRC as they inhibit EZH2-mediated methylation of histone and non-histone targets like β-catenin. Testing if β-catenin binding to the chromatin is regulated by EZH2-mediated β-catenin methylation. ChIP-seq was performed using FLAG antibody to determine β-catenin's enrichment on the chromatin in EV and PTEN knockdown SW480 cells expressing equal levels of FLAG-β-catenin untreated or treated with EZH2 inhibitor. SW480 cells not transfected with FLAG-expressing plasmid were used as a negative control.