Chem-CRISPR/dCas9 -a chemically induced platform for epigenome editing

Epigenetic aberration is one of the major driving factors in the initiation, promotion, and progression of human cancer and it is also often associated with acquired therapeutic resistance. Several chemical epigenetic modulators have been reported. However, results from animal models and clinical trials have indicated that severe on- and off-target toxicity is one of the leading factors behind failures in epidrug development. CRISPR/dCas9 technology provides a powerful tool for precise epigenetic regulation at the single-gene level. This approach requires ectopic expression of exogenous epigenetic modulatory proteins, which cause side effects and technical challenges for preparation and delivery. Recently, we have shown that Cas9 tagging with the peptide motif (FCPF) was recognized by perfluoro biphenyl derivatives. Here, we introduced the FCPF-tag into dCas9 and report a chemically induced platform for epigenome editing (Chem-CRISPR/dCas9FCPF). By conjugating JQ1, a BRD4 inhibitor, to perfluoro biphenyl (JQ1-FCPF), we demonstrate that JQ1-FCPF covalently binds to CRISPR/dCas9 and specifically inhibits BRD4 in proximity to the promoters/enhancers of c-MYC with the guidance of c-MYC sgRNAs. Thus, we achieved epigenetic modulation of c-MYC with high efficiency and specificity. Overall design: Analysis of gene expression upon various treatments Total RNA obtained from isolated K562 cells after 1 h treatment, including DMSO as control, JQ1 -sgRNA, JQ1 +sgRNA, JQ1-FCPF -sgRNA, JQ1-FCPF +sgRNA