Small-molecule inhibitors identify the RAD52-ssDNA interaction as critical for recovery from replication stress and for survival of BRCA2 deficient cells.
Sarah R Hengel, Eva Malacaria, Laura Folly da Silva Constantino, Fletcher E Bain, Andrea Diaz, Brandon G Koch, Liping Yu, Meng Wu, Pietro Pichierri, M Ashley Spies, Maria Spies
Author Information
Sarah R Hengel: Department of Biochemistry, University of Iowa, Iowa City, United States.
Eva Malacaria: Department of Environment and Health, Section of Experimental and Computational Carcinogenesis, Istituto Superiore di Sanita, Rome, Italy.
Laura Folly da Silva Constantino: Division of Medicinal and Natural Products Chemistry, Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, United States.
Fletcher E Bain: Department of Biochemistry, University of Iowa, Iowa City, United States.
Andrea Diaz: Department of Biochemistry, University of Iowa, Iowa City, United States.
Brandon G Koch: Department of Biochemistry, University of Iowa, Iowa City, United States.
Liping Yu: Department of Biochemistry, University of Iowa, Iowa City, United States.
Meng Wu: Department of Biochemistry, University of Iowa, Iowa City, United States.
Pietro Pichierri: Department of Environment and Health, Section of Experimental and Computational Carcinogenesis, Istituto Superiore di Sanita, Rome, Italy.
M Ashley Spies: Department of Biochemistry, University of Iowa, Iowa City, United States.
Maria Spies: Department of Biochemistry, University of Iowa, Iowa City, United States. ORCID
The DNA repair protein RAD52 is an emerging therapeutic target of high importance for BRCA-deficient tumors. Depletion of RAD52 is synthetically lethal with defects in tumor suppressors BRCA1, BRCA2 and PALB2. RAD52 also participates in the recovery of the stalled replication forks. Anticipating that ssDNA binding activity underlies the RAD52 cellular functions, we carried out a high throughput screening campaign to identify compounds that disrupt the RAD52-ssDNA interaction. Lead compounds were confirmed as RAD52 inhibitors in biochemical assays. Computational analysis predicted that these inhibitors bind within the ssDNA-binding groove of the RAD52 oligomeric ring. The nature of the inhibitor-RAD52 complex was validated through an in silico screening campaign, culminating in the discovery of an additional RAD52 inhibitor. Cellular studies with our inhibitors showed that the RAD52-ssDNA interaction enables its function at stalled replication forks, and that the inhibition of RAD52-ssDNA binding acts additively with BRCA2 or MUS81 depletion in cell killing.
