CRISPR-dCas9-based epigenetic editing is emerging as a promising strategy for precise regulation of cancer-associated epigenetic alterations. Unlike wild-type Cas9, which induces double-strand breaks, dCas9 is generated by introducing D10A and H840A mutations that abolish nuclease activity while retaining sgRNA-guided DNA binding. This allows dCas9 to serve as a programmable scaffold for recruiting epigenetic effectors. Fusions with DNMTs, TET enzymes, KRAB, or transcriptional activators such as VP64, p300, and the SAM system enable targeted methylation, demethylation, or histone modification, thereby modulating gene expression without altering DNA sequence. A central focus is the tumor suppressor LRIG1, a regulator of growth factor signaling (e.g., EGFR), which is often silenced in basal-like and triple-negative breast cancers (TNBC) through promoter hypermethylation. CpG island methylation prevents transcription factor binding, reducing LRIG1 expression and contributing to oncogenesis. Similar repression occurs in colorectal and cervical cancers. By guiding dCas9-activator complexes to the LRIG1 promoter, transcriptional activators and chromatin-modifying domains can erase repressive methylation, promote histone acetylation, and restore transcription. This reactivation of LRIG1 has shown potential to suppress tumor proliferation in preclinical models. Beyond LRIG1, dCas9-based systems represent a versatile platform for reactivating tumor suppressors or silencing oncogenes with minimal off-target damage. Advances in delivery technologies and in vivo applications underscore their translational promise, although challenges remain, including chromatin accessibility and off-target recruitment. Overall, CRISPR-dCas9-mediated epigenetic editing offers a transformative and reversible framework for therapeutic gene regulation, providing high precision and adaptability for cancer treatment and broader applications in precision medicine.
Ali Ownis (Sun,) studied this question.