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

doi:10.1016/j.isci.2024.108925

RNA helicase DDX3 regulates RAD51 localization and DNA damage repair in Ewing sarcoma

iScience. 2024 Jan 16;27(2):108925. doi: 10.1016/j.isci.2024.108925. eCollection 2024 Feb 16.

Authors

Matthew E Randolph^{1

2}, Marwa Afifi³, Aparna Gorthi⁴, Rachel Weil¹, Breelyn A Wilky⁵, Joshua Weinreb¹, Paul Ciero^{1

2}, Natalie Ter Hoeve⁶, Paul J van Diest⁶, Venu Raman^{5

7

8}, Alexander J R Bishop⁴, David M Loeb^{1

2

5}

Affiliations

¹ Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, Bronx, NY, USA.
² Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY, USA.
³ Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA.
⁴ Greehey Children's Cancer Research Institute and Department of Cell Systems & Anatomy, UT Health San Antonio, San Antonio, TX, USA.
⁵ Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA.
⁶ Department of Pathology, University Medical Centre Utrecht, Utrecht, the Netherlands.
⁷ Department of Radiology, Johns Hopkins University, Baltimore, MD, USA.
⁸ Department of Pharmacology, Johns Hopkins University, Baltimore, MD, USA.

Abstract

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.

Keywords: Biochemistry; Biological sciences; Cancer; Cell biology; Molecular biology; Natural sciences.

Abstract

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