Inhibition of PI3K-AKT-mTOR pathway sensitizes endometrial cancer cell lines to PARP inhibitors

BMC Cancer. 2017 Sep 8;17(1):638. doi: 10.1186/s12885-017-3639-0.


Background: Phosphatase and Tensin homolog (PTEN) is a tumor suppressor gene. Loss of its function is the most frequent genetic alteration in endometrioid endometrial cancers (70-80%) and high grade tumors (90%). We assessed the sensitivity of endometrial cancer cell lines to PARP inhibitors (olaparib and BMN-673) and a PI3K inhibitor (BKM-120), alone or in combination, in the context of their PTEN mutation status. We also highlighted a direct pathway linking PTEN to DNA repair.

Methods: Using endometrial cancer cellular models with known PTEN status, we evaluated their homologous recombination (HR) functionality by RAD51 foci formation assay. The 50% Inhibitory concentration (IC50) of PI3K and PARP inhibitors in these cells was assessed, and western blotting was performed to determine the expression of proteins involved in the PI3K/mTOR pathway. Moreover, we explored the interaction between RAD51 and PI3K/mTOR by immunofluorescence. Next, the combination effect of PI3K and PARP inhibitors on cell proliferation was evaluated by a clonogenic assay.

Results: Cells with mutated PTEN showed over-activation of the PI3K/mTOR pathway. These cells were more sensitive to PARP inhibition compared to PTEN wild-type cells. In addition, PI3K inhibitor treatment reduced RAD51 foci formation in PTEN mutated cells, and sensitized these cells to PARP inhibitor.

Conclusion: Targeting both PARP and PI3K might lead to improved personalized therapeutic approaches in endometrial cancer patients with PTEN mutations. Understanding the complex interaction of PTEN mutations with DNA repair in endometrial cancer will help to better select patients that are likely to respond to some of the new and costly targeted therapies.

Keywords: DNA repair pathway; Endometrial cancer; PARP inhibitor; PI3K/mTOR pathway; PTEN; RAD51.

MeSH terms

  • Antineoplastic Combined Chemotherapy Protocols / administration & dosage
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • DNA Repair / drug effects
  • Drug Resistance, Neoplasm
  • Endometrial Neoplasms / drug therapy*
  • Endometrial Neoplasms / genetics
  • Endometrial Neoplasms / pathology
  • Female
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Mutation
  • PTEN Phosphohydrolase / antagonists & inhibitors
  • PTEN Phosphohydrolase / genetics*
  • Phosphatidylinositol 3-Kinases / genetics*
  • Phosphoinositide-3 Kinase Inhibitors
  • Phthalazines / administration & dosage
  • Piperazines / administration & dosage
  • Poly(ADP-ribose) Polymerase Inhibitors / administration & dosage*
  • Rad51 Recombinase / genetics*
  • Signal Transduction / drug effects
  • TOR Serine-Threonine Kinases / genetics


  • Phosphoinositide-3 Kinase Inhibitors
  • Phthalazines
  • Piperazines
  • Poly(ADP-ribose) Polymerase Inhibitors
  • talazoparib
  • MTOR protein, human
  • TOR Serine-Threonine Kinases
  • Rad51 Recombinase
  • PTEN Phosphohydrolase
  • PTEN protein, human
  • olaparib