Protein expression of DNA damage repair proteins dictates response to topoisomerase and PARP inhibitors in triple-negative breast cancer

PLoS One. 2015 Mar 16;10(3):e0119614. doi: 10.1371/journal.pone.0119614. eCollection 2015.

Abstract

Patients with metastatic triple-negative breast cancer (TNBC) have a poor prognosis. New approaches for the treatment of TNBC are needed to improve patient survival. The concept of synthetic lethality, brought about by inactivating complementary DNA repair pathways, has been proposed as a promising therapeutic option for these tumors. The TNBC tumor type has been associated with BRCA mutations, and inhibitors of Poly (ADP-ribose) polymerase (PARP), a family of proteins that facilitates DNA repair, have been shown to effectively kill BRCA defective tumors by preventing cells from repairing DNA damage, leading to a loss of cell viability and clonogenic survival. Here we present preclinical efficacy results of combining the PARP inhibitor, ABT-888, with CPT-11, a topoisomerase I inhibitor. CPT-11 binds to topoisomerase I at the replication fork, creating a bulky adduct that is recognized as damaged DNA. When DNA damage was stimulated with CPT-11, protein expression of the nucleotide excision repair enzyme ERCC1 inversely correlated with cell viability, but not clonogenic survival. However, 4 out of the 6 TNBC cells were synergistically responsive by cell viability and 5 out of the 6 TNBC cells were synergistically responsive by clonogenic survival to the combination of ABT-888 and CPT-11. In vivo, the BRCA mutant cell line MX-1 treated with CPT-11 alone demonstrated significant decreased tumor growth; this decrease was enhanced further with the addition of ABT-888. Decrease in tumor growth correlated with an increase in double strand DNA breaks as measured by γ-H2AX phosphorylation. In summary, inhibiting two arms of the DNA repair pathway simultaneously in TNBC cell lines, independent of BRCA mutation status, resulted in un-repairable DNA damage and subsequent cell death.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antineoplastic Combined Chemotherapy Protocols / administration & dosage*
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology
  • Benzimidazoles / administration & dosage
  • Benzimidazoles / pharmacology
  • Camptothecin / administration & dosage
  • Camptothecin / analogs & derivatives
  • Camptothecin / pharmacology
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • DNA Breaks, Double-Stranded
  • DNA Repair / drug effects
  • DNA-Binding Proteins / metabolism*
  • Drug Synergism
  • Endonucleases / metabolism*
  • Female
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Irinotecan
  • Mice
  • Poly (ADP-Ribose) Polymerase-1
  • Poly(ADP-ribose) Polymerase Inhibitors / administration & dosage*
  • Poly(ADP-ribose) Polymerase Inhibitors / pharmacology
  • Poly(ADP-ribose) Polymerases / metabolism*
  • Topoisomerase I Inhibitors / administration & dosage*
  • Topoisomerase I Inhibitors / pharmacology
  • Triple Negative Breast Neoplasms / drug therapy*
  • Triple Negative Breast Neoplasms / metabolism
  • Xenograft Model Antitumor Assays

Substances

  • Benzimidazoles
  • DNA-Binding Proteins
  • Poly(ADP-ribose) Polymerase Inhibitors
  • Topoisomerase I Inhibitors
  • veliparib
  • Irinotecan
  • PARP1 protein, human
  • Poly (ADP-Ribose) Polymerase-1
  • Poly(ADP-ribose) Polymerases
  • ERCC1 protein, human
  • Endonucleases
  • Camptothecin