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Loss of POLE3-POLE4 unleashes replicative gap accumulation upon treatment with PARP inhibitors

Bethany Rebekah Hill1, Meryem Ozgencil1, Lauryn Buckley-Benbow1

  • 1Centre for Cancer Cell & Molecular Biology, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, EC1M 6BQ London, UK.

Cell Reports
|May 16, 2024
PubMed

Insights

Loss of POLE3-POLE4 subunits sensitizes cancer cells to PARP inhibitors (PARPis) by increasing replicative gaps. This finding bypasses common resistance mechanisms, offering a new strategy for PARPi-resistant cancers.

Area of Science:

  • Genetics
  • Molecular Biology
  • Cancer Research

Background:

  • PARP inhibitors (PARPis) are effective against BRCA1/BRCA2-mutated cancers.
  • Drug resistance to PARPis is a significant clinical challenge.
  • Understanding PARPi sensitivity mechanisms is crucial for improving cancer therapy.

Purpose of the Study:

  • To investigate the role of DNA polymerase epsilon (Polε) subunits in PARPi sensitivity.
  • To identify novel mechanisms that sensitize cancer cells to PARPis.

Main Methods:

  • Generated POLE3-POLE4 knockout (KO) cancer cell lines.
  • Assessed PARPi sensitivity in KO cells.
  • Analyzed RAD51 foci formation and replicative gaps.
  • Investigated the role of PRIMPOL and 53BP1.

Main Results:

  • Loss of POLE3-POLE4 subunits sensitizes cancer cells to PARPis independently of Polε levels.
  • This sensitization is not due to defects in homologous recombination (RAD51 foci).
  • PARPi treatment induces replicative gaps in POLE3-POLE4 KO cells via PRIMPOL.
  • Loss of POLE3-POLE4 sensitizes BRCA1-silenced cells to PARPis.
  • 53BP1 knockdown does not rescue PARPi sensitivity in POLE3-POLE4 KO cells.

Conclusions:

  • Loss of POLE3-POLE4 subunits represents a novel mechanism for sensitizing cancer cells to PARPis.
  • This pathway bypasses common PARPi resistance mechanisms involving 53BP1.
  • Targeting POLE3-POLE4 or related pathways could overcome PARPi resistance in cancer treatment.
Keywords:
CP: CancerCP: Molecular biologyPARP inhibitorsPOLE3-POLE4replicative gaps

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