Combined inhibition of DDR1 and CDK4/6 induces synergistic effects in ER-positive, HER2-negative breast cancer with PIK3CA/AKT1 mutations

Oncogene. 2021 Jul;40(26):4425-4439. doi: 10.1038/s41388-021-01819-0. Epub 2021 Jun 9.

Abstract

Molecular alterations in the PI3K/AKT pathway occur frequently in hormone receptor-positive breast tumors. Patients with ER-positive, HER2-negative metastatic breast cancer are often treated with CDK4/6 inhibitors such as palbociclib in combination with endocrine therapy. Although this is an effective regimen, most patients ultimately progress. The purpose of this study was identifying synthetic lethality partners that can enhance palbociclib's antitumor efficacy in the presence of PIK3CA/AKT1 mutations. We utilized a barcoded shRNA library to determine critical targets for survival in isogenic MCF7 cells with PIK3CA/AKT1 mutations. We demonstrated that the efficacy of palbociclib is reduced in the presence of PIK3CA/AKT1 mutations. We also identified that the downregulation of discoidin domain receptor 1 (DDR1) is synthetically lethal with palbociclib. DDR1 knockdown and DDR1 pharmacological inhibitor decreased cell growth and inhibited cell cycle progression in all cell lines, while enhanced the sensitivity of PIK3CA/AKT1 mutant cells to palbociclib. Combined treatment of palbociclib and 7rh further induced cell cycle arrest in PIK3CA/AKT1 mutant cell lines. In vivo, 7rh significantly enhanced palbociclib's antitumor efficacy. Our data indicates that DDR1 inhibition can augment cell cycle suppressive effect of palbociclib and could be effective strategy for targeted therapy of ER-positive, HER2-negative breast cancers with PI3K pathway activation.

Publication types

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

MeSH terms

  • Animals
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology
  • Breast Neoplasms / drug therapy
  • Breast Neoplasms / genetics*
  • Cell Cycle Checkpoints / drug effects
  • Cell Cycle Checkpoints / genetics
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cell Proliferation / genetics
  • Class I Phosphatidylinositol 3-Kinases / genetics*
  • Cyclin-Dependent Kinases / antagonists & inhibitors*
  • Discoidin Domain Receptor 1 / antagonists & inhibitors*
  • Female
  • Humans
  • MCF-7 Cells
  • Mutation / genetics
  • Protein Kinase Inhibitors / pharmacology
  • Proto-Oncogene Proteins c-akt / genetics*
  • Receptor, ErbB-2 / genetics*
  • Receptors, Estrogen / genetics*
  • Signal Transduction / drug effects
  • Signal Transduction / genetics

Substances

  • Protein Kinase Inhibitors
  • Receptors, Estrogen
  • Class I Phosphatidylinositol 3-Kinases
  • PIK3CA protein, human
  • DDR1 protein, human
  • Discoidin Domain Receptor 1
  • Receptor, ErbB-2
  • AKT1 protein, human
  • Proto-Oncogene Proteins c-akt
  • Cyclin-Dependent Kinases