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ATR inhibition preferentially targets homologous recombination-deficient tumor cells

M Krajewska1, R S N Fehrmann1, P M Schoonen1

  • 1Department of Medical Onclology, University Medical Center Groningen, University of Groningen, The Netherlands.

Oncogene
|September 2, 2014
PubMed

Insights

Defective homologous recombination (HR) repair in cancer cells creates genomic instability but also reliance on ATR/Chk1 signaling. Inhibiting these pathways preferentially kills HR-deficient cancer cells, revealing potential therapeutic targets.

Area of Science:

  • Genetics
  • Cancer Biology
  • Molecular Oncology

Background:

  • Homologous recombination (HR) is crucial for repairing DNA double-strand breaks, and its defects lead to genomic instability.
  • HR-deficient cancers paradoxically survive despite genomic instability, suggesting acquired compensatory mechanisms.
  • Identifying these survival mechanisms is key to developing targeted therapies for HR-defective cancers.

Purpose of the Study:

  • To identify characteristics that enable cancer cells to survive genomic instability caused by HR defects.
  • To uncover potential therapeutic targets for HR-deficient cancers.

Main Methods:

  • Cytogenetic analysis of 1143 ovarian cancers to correlate genomic instability with replication checkpoint gene amplification (ATR, CHEK1).
  • Modeling HR deficiency by inactivating Rad51 to study its effects on replication dynamics and signaling.
  • Inhibiting ATR or Chk1 in HR-deficient cancer cells to assess their sensitivity.

Main Results:

  • Genomic instability in ovarian cancers correlated with amplification of ATR and CHEK1 genes.
  • Rad51 inactivation led to defective HR, aberrant replication, and increased ATR/Chk1-mediated replication stress signaling.
  • Inhibition of ATR or Chk1 selectively killed HR-deficient cancer cells.

Conclusions:

  • Defective HR repair induces reliance on replication checkpoint signaling (ATR/Chk1).
  • ATR and Chk1 inhibitors show preferential efficacy against HR-deficient cancer cells.
  • Replication checkpoint kinases represent promising therapeutic targets for HR-defective cancers.

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