Abstract B37: PARP inhibitor olaparib induces genomic instability in normal mammalian cells

Poly(ADP-ribose) polymerases (PARPs) are the first proteins involved in cellular DNA damage response pathways to be targeted by specific inhibitors for clinical benefit. Tumors with defects in homologous recombination (HR) are hypersensitive to PARP inhibitors (PARPi), and early phase clinical trials have been promising in patients with advanced BRCA1 and BRCA2-associated breast, ovary and prostate cancer. Unlike HR-defective cells, HR-proficient cells manifest low cytotoxicity when exposed to PARPi. Nonetheless, they mount a DNA damage response and show a genomic instability phenotype as demonstrated by an increased frequency of sister chromatid exchange. To study molecular mechanisms underlying PARPi-generated genomic instability, we took advantage of olaparib an agent in clinical use. Our results in mouse embryonic stem cells show that olaparib increases HR leading to copy number alterations and induces a mutator phenotype. Further, using a genome wide approach we finally demonstrate that PARPi treatment increases DNA double-strand breaks genome-wide which can lead to translocations and other genome aberrations. Our findings have important implications for therapies with regard to sustained genotoxicity to normal cells. Genomic instability arising from PARPi warrants consideration in prevention strategies or for non-oncologic indications.Citation Format: Fabio Vanoli, Shuhei Ito, Richard L. Frock, Frederick W. Alt, Mary Ellen Moynahan, Maria Jasin. PARP inhibitor olaparib ...
Source: Molecular Cancer Research - Category: Cancer & Oncology Authors: Tags: Therapies Targeting Checkpoints and Mismatch Repair: Poster Presentations - Proffered Abstracts Source Type: research