Small molecule inhibition of the CHFR-PARP1 interaction as novel approach to overcome intrinsic taxane resistance in cancer

• Type of Material: Article
• Authors: Seth A. Brodie, Emory University; Ge Li, Emory University; R. Harvey, Emory University; Fadlo Khuri, Emory University; Paula Vertino, Emory University; Johann Brandes, Emory University
• Language: English
• Date: 2015-10-13
• Publisher: Impact Journals
• Publication Version: Final Published Version
• Copyright Statement: © 2015 Brodie et al.
• License: Creative Commons Attribution 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.18632/oncotarget.5040
• Title of Journal or Parent Work: Oncotarget
• ISSN: 1949-2553
• Volume: 6
• Issue: 31
• Start Page: 30773
• End Page: 30786
• Grant/Funding Information: Veterans’ Health Administration Career Development Award 7-IK2BX001283-03 to JCB; NCI-5 P50 CA128613-02 Career Development Project to JCB; NCI-P30CA138292 pilot grant to JCB.; Uniting against Lung Cancer/Lungevity Foundation Research Award to JCB; SunTrust Scholar Award to JCB; Cohen Family Scholar Award to JCB; Elsa U Pardee Foundation Research Award to JCB.; CHEST Foundation /Lungevity Foundation Clinical Lung Cancer Research Award to JCB.; This research project was supported in part by the Emory University Integrated Cellular Imaging Microscopy Core of the Winship Cancer Institute of Emory University under award number P30CA138292.
• Keywords: EXPRESSION; Oncology; HYPERMETHYLATION; PROTEIN; SENSITIVITY; mitotic checkpoint; MITOTIC CHECKPOINT; Cell Biology; CHFR; SUPPRESSION; Life Sciences & Biomedicine; Science & Technology; chemoresistance; UBIQUITINATION; lung cancer; ENDOMETRIAL CANCER; taxanes; EPIGENETIC INACTIVATION
• Research Categories: Health Sciences, Oncology; Biology, Cell

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.