RNA helicase DDX3 regulates RAD51 localization and DNA damage repair in Ewing sarcoma
Matthew E. Randolph,
Marwa Afifi,
Aparna Gorthi,
Rachel Weil,
Breelyn A. Wilky,
Joshua Weinreb,
Paul Ciero,
Natalie ter Hoeve,
Paul J. van Diest,
Venu Raman,
Alexander J.R. Bishop,
David M. Loeb
Affiliations
Matthew E. Randolph
Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY, USA
Marwa Afifi
Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
Aparna Gorthi
Greehey Children’s Cancer Research Institute and Department of Cell Systems & Anatomy, UT Health San Antonio, San Antonio, TX, USA
Rachel Weil
Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA
Breelyn A. Wilky
Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA
Joshua Weinreb
Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA
Paul Ciero
Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY, USA
Natalie ter Hoeve
Department of Pathology, University Medical Centre Utrecht, Utrecht, the Netherlands
Paul J. van Diest
Department of Pathology, University Medical Centre Utrecht, Utrecht, the Netherlands
Venu Raman
Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA; Department of Radiology, Johns Hopkins University, Baltimore, MD, USA; Department of Pharmacology, Johns Hopkins University, Baltimore, MD, USA
Alexander J.R. Bishop
Greehey Children’s Cancer Research Institute and Department of Cell Systems & Anatomy, UT Health San Antonio, San Antonio, TX, USA
David M. Loeb
Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA; Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY, USA; Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA; Corresponding author
Summary: We previously demonstrated that RNA helicase DDX3X (DDX3) can be a therapeutic target in Ewing sarcoma (EWS), but its role in EWS biology remains unclear. The present work demonstrates that DDX3 plays a unique role in DNA damage repair (DDR). We show that DDX3 interacts with several proteins involved in homologous recombination, including RAD51, RECQL1, RPA32, and XRCC2. In particular, DDX3 colocalizes with RAD51 and RNA:DNA hybrid structures in the cytoplasm of EWS cells. Inhibition of DDX3 RNA helicase activity increases cytoplasmic RNA:DNA hybrids, sequestering RAD51 in the cytoplasm, which impairs nuclear translocation of RAD51 to sites of double-stranded DNA breaks, thus increasing sensitivity of EWS to radiation treatment, both in vitro and in vivo. This discovery lays the foundation for exploring new therapeutic approaches directed at manipulating DDR protein localization in solid tumors.
