Abstract
Inhibitors of poly-ADP-ribose polymerase 1 (PARPi) are highly effective in killing cells deficient in homologous recombination (HR); thus, PARPi have been clinically utilized to successfully treat BRCA2-mutant tumors. However, positive response to PARPi is not universal, even among patients with HR-deficiency. Here, we present the results of genome-wide CRISPR knockout and activation screens which reveal genetic determinants of PARPi response in wildtype or BRCA2-knockout cells. Strikingly, we report that depletion of the ubiquitin ligase HUWE1, or the histone acetyltransferase KAT5, top hits from our screens, robustly reverses the PARPi sensitivity caused by BRCA2-deficiency. We identify distinct mechanisms of resistance, in which HUWE1 loss increases RAD51 levels to partially restore HR, whereas KAT5 depletion rewires double strand break repair by promoting 53BP1 binding to double-strand breaks. Our work provides a comprehensive set of putative biomarkers that advance understanding of PARPi response, and identifies novel pathways of PARPi resistance in BRCA2-deficient cells.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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BRCA2 Protein / genetics
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BRCA2 Protein / metabolism
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Biomarkers
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Clustered Regularly Interspaced Short Palindromic Repeats*
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DNA Damage
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DNA Repair
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Gene Knockout Techniques
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HeLa Cells
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Homologous Recombination / drug effects
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Humans
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Lysine Acetyltransferase 5 / metabolism
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Mad2 Proteins / metabolism
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Poly(ADP-ribose) Polymerase Inhibitors / isolation & purification*
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Poly(ADP-ribose) Polymerase Inhibitors / pharmacology*
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Poly(ADP-ribose) Polymerases / drug effects*
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Rad51 Recombinase / genetics
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Rad51 Recombinase / metabolism
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Tumor Suppressor Proteins / genetics
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Tumor Suppressor Proteins / metabolism
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Tumor Suppressor p53-Binding Protein 1
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Ubiquitin-Protein Ligases / genetics
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Ubiquitin-Protein Ligases / metabolism
Substances
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BRCA2 Protein
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BRCA2 protein, human
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Biomarkers
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MAD2L2 protein, human
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Mad2 Proteins
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Poly(ADP-ribose) Polymerase Inhibitors
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TP53BP1 protein, human
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Tumor Suppressor Proteins
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Tumor Suppressor p53-Binding Protein 1
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KAT5 protein, human
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Lysine Acetyltransferase 5
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HUWE1 protein, human
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Ubiquitin-Protein Ligases
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Poly(ADP-ribose) Polymerases
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RAD51 protein, human
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Rad51 Recombinase