title: Therapeutic potential of poly(ADP-ribose) polymerase inhibitor AG014699 in human cancers with mutated or methylated BRCA1 or BRCA2.
abstract: BACKGROUND
  Mutations in BRCA1 and BRCA2 (BRCA1/2), components of the homologous recombination DNA repair (HRR) pathway, are associated with hereditary breast and ovarian cancers. Poly(ADP-ribose) polymerase (PARP) inhibitors are selectively cytotoxic to animal cells with defective HRR, but results in human cancer cells have been contradictory. We undertook, to our knowledge, the first comprehensive in vitro and in vivo investigations of the antitumor activity of the PARP inhibitor AG014699 in human cancer cells carrying mutated or epigenetically silenced BRCA1/2.
  
  
  METHODS
  We used nine human cell lines, four with nonmutated BRCA1/2 (MCF7, MDA-MB-231, and HCC1937-BRCA1 [breast cancer] and OSEC-2 [ovarian surface epithelial]), two with mutated BRCA1 (MDA-MB-436 and HCC1937 [breast cancer]), one with mutated BRCA2 (CAPAN-1 [pancreatic cancer]), one that was heterozygous for BRCA2 (OSEC-1 [ovarian surface epithelial]), and one with epigenetically silenced BRCA1 (UACC3199 [breast cancer]), and two Chinese hamster ovary cell lines, parental AA8 and XRCC3 mutated IRS 1SF. We assessed cytotoxicity, DNA damage, and HRR function. Antitumor activity of AG014699 was determined by growth of xenograft tumors (five mice per treatment group). Long-term safety of AG014699 was assessed.
  
  
  RESULTS
  AG014699 (≤10 μM) was cytotoxic to cells with mutated BRCA1/2 or XRCC3 and to UACC3199 cells with epigenetically silenced BRCA1 but not to cells without BRCA1/2 or XRCC3 mutations or that were heterozygous for BRCA2 mutation. AG014699 induced DNA double-strand breaks in all nine cell lines studied. HRR was observed only in cells with functional BRCA1/2 proteins. Growth of xenograft tumors with BRCA1/2 mutations or with epigenetically silenced BRCA1 was reduced by AG014699 treatment, and combination treatment with AG014699 plus carboplatin was more effective than either drug alone. AG014699 was not toxic in mice with nonmutated or heterozygous BRCA2.
  
  
  CONCLUSIONS
  Human cancer cells or xenograft tumors with mutated or epigenetically silenced BRCA1/2 were sensitive to AG014699 monotherapy, indicating a potential role for PARP inhibitors in sporadic human cancers.
authors.affiliation: Northern Institute for Cancer Research, University of Newcastle Upon Tyne, Medical School, Newcastle Upon Tyne, NE2 4HH, UK.
authors.forename: Yvette
authors.initials: Y
authors.lastname: Drew
authors.forename: Evan A
authors.initials: EA
authors.lastname: Mulligan
authors.forename: Wan-Tse
authors.initials: WT
authors.lastname: Vong
authors.forename: Huw D
authors.initials: HD
authors.lastname: Thomas
authors.forename: Samra
authors.initials: S
authors.lastname: Kahn
authors.forename: Suzanne
authors.initials: S
authors.lastname: Kyle
authors.forename: Asima
authors.initials: A
authors.lastname: Mukhopadhyay
authors.forename: Gerrit
authors.initials: G
authors.lastname: Los
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Hostomsky
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Plummer
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Edmondson
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Curtin
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics; D016466:CHO Cells; D016190:Carboplatin / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D003412:Cricetulus; D019175:DNA Methylation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D020868:Gene Silencing; D019398:Genes, BRCA1; D024522:Genes, BRCA2; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D051379:Mice; D008819:Mice, Nude; D009154:Mutation; D009369:Neoplasms / Q000188:drug therapy* / Q000235:genetics*; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000235:genetics; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000235:genetics; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D014183:Transplantation, Heterologous
chemical_list: D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D007211:Indoles; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; C531549:rucaparib; D016190:Carboplatin; D011065:Poly(ADP-ribose) Polymerases