title: Small molecule inhibition of the CHFR-PARP1 interaction as novel approach to overcome intrinsic taxane resistance in cancer.
abstract: The mitotic checkpoint protein CHFR has emerged as a major mediator of taxane resistance in cancer. Here we show that CHFR's PAR-binding zinc finger domain (PBZ) mediates a protein interaction with poly-ADP ribosylated PARP1 leading to stabilization of CHFR. Disruption of the CHFR-PARP1 interaction through either PARP1 shRNA-mediated knockdown or overexpression of a PBZ domain peptide induces loss of CHFR protein expression. In an attempt to exploit this observation therapeutically, and to develop compounds with synthetic lethality in combination with taxanes, we performed a high-throughput computational screen of 5,256,508 chemical structures against the published crystal structure of the CHFR PBZ domain to identify candidate small molecule CHFR protein-protein interaction inhibitors. The 10 compounds with the best docking scores (< -9.7) were used for further in vitro testing. One lead compound in particular, termed 'A3', completely disrupted the protein-protein interaction between CHFR and PARP1, resulting in the inhibition of mitotic checkpoint function, and led to therapeutic synergy with docetaxel in cell viability and colony formation assays. In mouse xenografts, i.p. administration of 'A3' led to a significant reduction in nuclear CHFR protein expression with a maximal effect 4 hours after administration, confirming relevant pharmacodynamics following the peak of 'A3' plasma concentration in vivo. Furthermore, combination of A3 and taxane led to significant reduction of implanted tumor size without increase in hematological, hepatic or renal toxicity. These findings provide a proof-of-principle that small molecule inhibition of CHFR PBZ domain interaction is a novel potential therapeutic approach to increase the efficacy of taxane-based chemotherapy in cancer.
authors.affiliation: Department of Hematology and Medical Oncology, Emory University, Atlanta, GA, USA.|Winship Cancer Institute, Emory University, Atlanta, GA, USA.
authors.forename: Seth A
authors.initials: SA
authors.lastname: Brodie
authors.affiliation: Department of Hematology and Medical Oncology, Emory University, Atlanta, GA, USA.|Winship Cancer Institute, Emory University, Atlanta, GA, USA.
authors.forename: Ge
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Hematology and Medical Oncology, Emory University, Atlanta, GA, USA.|Winship Cancer Institute, Emory University, Atlanta, GA, USA.
authors.forename: Donald
authors.initials: D
authors.lastname: Harvey
authors.affiliation: Department of Hematology and Medical Oncology, Emory University, Atlanta, GA, USA.|Winship Cancer Institute, Emory University, Atlanta, GA, USA.
authors.forename: Fadlo R
authors.initials: FR
authors.lastname: Khuri
authors.affiliation: Department of Radiation Oncology, Emory University, Atlanta, GA, USA.|Winship Cancer Institute, Emory University, Atlanta, GA, USA.
authors.forename: Paula M
authors.initials: PM
authors.lastname: Vertino
authors.affiliation: Department of Hematology and Medical Oncology, Emory University, Atlanta, GA, USA.|Winship Cancer Institute, Emory University, Atlanta, GA, USA.|Tennessee Oncology, Nashville, TN, USA.
authors.forename: Johann C
authors.initials: JC
authors.lastname: Brandes
mesh_terms: D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D000077143:Docetaxel; D004305:Dose-Response Relationship, Drug; D055808:Drug Discovery / Q000379:methods; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D005260:Female; D057166:High-Throughput Screening Assays; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D008938:Mitosis / Q000187:drug effects; D062105:Molecular Docking Simulation; D009154:Mutation; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000071137:Poly (ADP-Ribose) Polymerase-1; D000067856:Poly(ADP-ribose) Polymerase Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry / Q000378:metabolism; D000075223:Poly-ADP-Ribose Binding Proteins; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D013329:Structure-Activity Relationship; D043823:Taxoids / Q000494:pharmacology*; D013997:Time Factors; D014162:Transfection; D047368:Tumor Burden / Q000187:drug effects; D044767:Ubiquitin-Protein Ligases; D023041:Xenograft Model Antitumor Assays
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D018797:Cell Cycle Proteins; D009363:Neoplasm Proteins; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D000075223:Poly-ADP-Ribose Binding Proteins; D043823:Taxoids; D000077143:Docetaxel; C412002:CHFR protein, human; D044767:Ubiquitin-Protein Ligases; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases
keywords: CHFR; chemoresistance; lung cancer; mitotic checkpoint; taxanes