Teoh PJ1, An O1, Chung TH1, Chooi JY1, Toh SHM1, Fan S2, Wang W3, Koh BTH4, Fullwood MJ5, Ooi MG6, de Mel S7, Soekojo CY6, Chen L8, Ng SB9, Yang H1, Chng WJ10.
1 Cancer Science Institute of Singapore, National University of Singapore, Singapore.
2 Department of Pathology, National University Hospital, National University Health System, Singapore.
3 Department of Orthopaedic Surgery, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
4 Department of Orthopaedic Surgery, National University Hospital, Singapore.
5 Cancer Science Instittue of Singapore, National University of Singapore, Singapore.
6 National University Cancer Institute, Singapore.
7 Department of Haematology-Oncology, National University Cancer Institute of Singapore, National University Health System, Singapore.
8 Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
9 Department of Pathology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
10 Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
DNA alterations have been extensively reported in multiple myeloma (MM); however, they cannot yet fully explain all the biological and molecular abnormalities in MM, which remains till this day an incurable disease with eventual emergence of refractory disease. Recent years have seen abnormalities at the RNA levels being reported to possess potential biological relevance in cancers. ADAR1-mediated-A-to-I-editing is an important post-transcriptional mechanism in human physiology and the biological implication of its abnormality, especially at the global level, is underexplored in MM. In this study, we seek to define the biological implications of RNA editing and how it contributes to MM pathogenesis. Herein, we identified that the MM transcriptome is aberrantly hyper-edited, owing to the overexpression of ADAR1. These events were associated with patients’ survival independently of 1q21 amplifications and could affect patients’ responsiveness to different treatment regimes. Our functional assays established ADAR1 to be oncogenic, driving cellular growth and proliferation in an editing-dependent manner. In addition, we identified NEIL1 (base-excision repair gene) as an essential and a ubiquitously edited ADAR1 target in MM. The recoded NEIL1 protein showed defective oxidative damage repair capacity and gain-of-function properties. Collectively, our data demonstrated that ADAR1-mediated-A-to-I editing is both clinically and biologically relevant in MM. These data unraveled novel insights into MM molecular pathogenesis at the global RNA level.