Pluto Bioinformatics

GSE145639: Epigenetic therapy induces transcription of Inverted SINEs and ADAR1 dependency

Bulk RNA sequencing

In this study we show that intronic and intergenic SINE elements, specifically inverted repeats (IR) Alus, are the major source of drug-induced immunogenic dsRNA. These IR-Alus are frequently located downstream of orphan CpG Islands (CGIs). In mammals, the enzyme Adenosine Deaminases Acting on RNA (ADAR1) targets and destabilizes IR-Alu dsRNA, which prevents activation of MDA5. We found that ADAR1 establishes a negative feedback loop, restricting the viral mimicry response to epigenetic therapy. Depletion of ADAR1 in patient-derived cancer cells potentiates the efficacy of epigenetic therapy, restraining tumour growth and reducing cancer initiation. Thus, epigenetic therapies trigger viral mimicry by inducing a subset of IR-Alus, leading to an ADAR1 dependency. Our findings suggest that combining epigenetic therapies with ADAR1 inhibitors represents a promising new strategy for cancer treatment. SOURCE: Sajid,A,Marhon (sajid.marhon@gmail.com) - Princess Margaret Cancer Centre