Post-transcriptional adenosine-to-inosine RNA editing mediated by adenosine deaminase acting on RNA1 (ADAR1) promotes cancer progression and therapeutic resistance. However, ADAR1 editase-dependent mechanisms governing leukemia stem cell (LSC) generation have not been elucidated. In blast crisis chronic myeloid leukemia (BC CML), we show that increased JAK2 signaling and BCR-ABL1 amplification activate ADAR1. In a humanized BC CML mouse model, combined JAK2 and BCR-ABL1 inhibition prevents LSC self-renewal commensurate with ADAR1 downregulation. Lentiviral ADAR1 wild-type, but not an editing-defective ADAR1E912A mutant, induces self-renewal gene expression and impairs biogenesis of stem cell regulatory let-7 microRNAs. Combined RNA sequencing, qRT-PCR, CLIP-ADAR1, and pri-let-7 mutagenesis data suggest that ADAR1 promotes LSC generation via let-7 pri-microRNA editing and LIN28B upregulation. A small-molecule tool compound antagonizes ADAR1’s effect on LSC self-renewal in stromal co-cultures and restores let-7 biogenesis. Thus, ADAR1 activation represents a unique therapeutic vulnerability in LSCs with active JAK2 signaling.
Bibliographical noteFunding Information:
This work was supported by the Moores Family Foundation , California Institute for Regenerative Medicine (CIRM) grants ( RN2-00910-1 ; DR1-01430 ; RS1-00228-1 ), Cancer Stem Cell Consortium funding from Genome Canada and the Ontario Genomics Institute ( OGI-047 ), NIH National Institute of General Medical Sciences grant 5K12GM068524 , NIH National Cancer Institute (NCI) grant 2P30CA023100-28 , NIH NCI grant R21CA189705 , The Sanford Stem Cell Clinical Center , The San Diego Foundation , The Ratner Family Foundation , The Mizrahi Family Foundation , and the Canadian Institute of Health Research ( CSC-105367 ). This work was also supported in part by the Office of the Assistant Secretary of Defense for Health Affairs through the Peer Reviewed Cancer Research Program under Award No. W81XWH-14-1-0121 (C.H.M.J.). Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the Department of Defense. The authors wish to thank Dr. Dennis Carson and Dr. Ida Deichaite for scientific advice, Dr. Wenxue Ma (University of California, San Diego) for assistance with humanized mouse model experiments, Dr. Stefan Maas (Lehigh University) for providing the luciferase RNA editing reporter construct, and Canada’s Michael Smith Genome Sciences Centre Library Construction, Sequencing, and Bioinformatics teams. M.P. holds the Daniel Hays endowed chair in Cancer Research at UCR.
© 2016 Elsevier Inc.