GSK-3484862 targets DNMT1 for degradation in cells
Maintaining genomic methylation patterns at DNA replication forks by DNMT1 is crucial for accurate mitotic inheritance. DNMT1 is frequently overexpressed in cancer cells, and hypomethylating agents like azacytidine and decitabine are currently used to treat hematologic malignancies. However, the toxicity of these cytidine analogs and their limited effectiveness in solid tumors have restricted their broader clinical application. GSK-3484862 is a newly developed, non-nucleoside DNMT1-selective inhibitor containing dicyanopyridine, which shows low cellular toxicity.
In this study, we demonstrate that GSK-3484862 targets DNMT1 for degradation in both cancer cell lines and murine embryonic stem cells (mESCs). The depletion of DNMT1 occurs rapidly, within hours of treatment, leading to global hypomethylation. This degradation process is proteasome-dependent and does not result in a decrease in DNMT1 mRNA levels. In mESCs, the degradation of Dnmt1 induced by GSK-3484862 relies on the Dnmt1 accessory factor Uhrf1 and its E3 ubiquitin ligase activity. Additionally, we found that the depletion of Dnmt1 and the resulting DNA hypomethylation are reversible upon the removal of the compound.
These findings suggest that this DNMT1-selective degrader/inhibitor could serve as a valuable tool for investigating the connections between DNA methylation and gene expression, as well as for identifying downstream effectors that regulate cellular responses to altered DNA methylation patterns in a tissue- and cell-specific manner.