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Reduced PAK1 activity sensitizes FA/BRCA-proficient breast cancer cells to PARP inhibition

Olga Villamar Cruz1, Tatiana Y Prudnikova2, Daniela Araiza-Olivera2

  • 1UBIMED, Facultad de Estudios Superiores-Iztacala, UNAM, Tlalnepantla, Estado de México, Mexico.

Oncotarget
|October 15, 2016
PubMed

Insights

Inhibiting p21-activated kinase 1 (PAK1) impairs DNA repair, making cancer cells sensitive to PARP inhibitors. This strategy could expand PARP inhibitor use to more breast cancer patients by targeting PAK1-overexpressing tumors.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cancer Genetics

Background:

  • Homologous recombination (HR) deficiency, often due to Fanconi Anemia (FA)/BRCA mutations, confers sensitivity to poly(ADP-ribose) polymerase (PARP) inhibitors.
  • FA/BRCA-deficient tumors are a small subset of breast cancers, limiting PARP inhibitor monotherapy's broad applicability.
  • p21-activated kinase 1 (PAK1) is overexpressed in a significant portion of breast cancers and regulates cellular processes.

Purpose of the Study:

  • To investigate the role of PAK1 in DNA repair pathways, specifically homologous recombination (HR).
  • To evaluate the therapeutic potential of combined PAK1 and PARP inhibition in breast cancer.
  • To determine if targeting PAK1 can sensitize FA/BRCA-proficient cancers to PARP inhibitors.

Main Methods:

  • Depletion and pharmacological inhibition of PAK1.
  • Assessment of DNA repair capacity by Homologous Recombination (HR).
  • Synergistic effects of combined PAK1 and PARP inhibition in vitro and in a xenograft mouse model.

Main Results:

  • PAK1 inhibition down-regulated FA/BRCA pathway genes and impaired HR DNA repair.
  • Combined PAK1 and PARP inhibition demonstrated synergistic effects, including enhanced apoptosis and reduced colony formation.
  • Treatment delayed tumor growth in a xenograft model of PAK1-overexpressing breast cancer.

Conclusions:

  • Reduced PAK1 activity compromises FA/BRCA pathway function, sensitizing cells to PARP inhibitors.
  • Inhibiting PAK1 in PAK1-amplified/overexpressing breast cancers is a viable strategy to broaden PARP inhibitor utility.
  • This approach may extend PARP inhibitor benefits to FA/BRCA-proficient breast cancers.
Keywords:
DNA repairPAK1small molecule inhibitortransformationFanconi anemia

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