Identification of regulators of poly-ADP-ribose polymerase inhibitor response through complementary CRISPR knockout and activation screens

Nat Commun. 2020 Nov 30;11(1):6118. doi: 10.1038/s41467-020-19961-w.

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

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • BRCA2 Protein / genetics
  • BRCA2 Protein / metabolism
  • Biomarkers
  • Clustered Regularly Interspaced Short Palindromic Repeats*
  • DNA Damage
  • DNA Repair
  • Gene Knockout Techniques
  • HeLa Cells
  • Homologous Recombination / drug effects
  • Humans
  • Lysine Acetyltransferase 5 / metabolism
  • Mad2 Proteins / metabolism
  • Poly(ADP-ribose) Polymerase Inhibitors / isolation & purification*
  • Poly(ADP-ribose) Polymerase Inhibitors / pharmacology*
  • Poly(ADP-ribose) Polymerases / drug effects*
  • Rad51 Recombinase / genetics
  • Rad51 Recombinase / metabolism
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism
  • Tumor Suppressor p53-Binding Protein 1
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism

Substances

  • BRCA2 Protein
  • BRCA2 protein, human
  • Biomarkers
  • MAD2L2 protein, human
  • Mad2 Proteins
  • Poly(ADP-ribose) Polymerase Inhibitors
  • TP53BP1 protein, human
  • Tumor Suppressor Proteins
  • Tumor Suppressor p53-Binding Protein 1
  • KAT5 protein, human
  • Lysine Acetyltransferase 5
  • HUWE1 protein, human
  • Ubiquitin-Protein Ligases
  • Poly(ADP-ribose) Polymerases
  • RAD51 protein, human
  • Rad51 Recombinase