title: Identification of small molecule inhibitors of ERCC1-XPF that inhibit DNA repair and potentiate cisplatin efficacy in cancer cells.
abstract: ERCC1-XPF heterodimer is a 5'-3' structure-specific endonuclease which is essential in multiple DNA repair pathways in mammalian cells. ERCC1-XPF (ERCC1-ERCC4) repairs cisplatin-DNA intrastrand adducts and interstrand crosslinks and its specific inhibition has been shown to enhance cisplatin cytotoxicity in cancer cells. In this study, we describe a high throughput screen (HTS) used to identify small molecules that inhibit the endonuclease activity of ERCC1-XPF. Primary screens identified two compounds that inhibit ERCC1-XPF activity in the nanomolar range. These compounds were validated in secondary screens against two other non-related endonucleases to ensure specificity. Results from these screens were validated using an in vitro gel-based nuclease assay. Electrophoretic mobility shift assays (EMSAs) further show that these compounds do not inhibit the binding of purified ERCC1-XPF to DNA. Next, in lung cancer cells these compounds potentiated cisplatin cytotoxicity and inhibited DNA repair. Structure activity relationship (SAR) studies identified related compounds for one of the original Hits, which also potentiated cisplatin cytotoxicity in cancer cells. Excitingly, dosing with NSC16168 compound potentiated cisplatin antitumor activity in a lung cancer xenograft model. Further development of ERCC1-XPF DNA repair inhibitors is expected to sensitize cancer cells to DNA damage-based chemotherapy.
authors.affiliation: Department of Biochemistry & Cancer Biology, University of Toledo Health Science Campus, Toledo, OH, USA.
authors.forename: Sanjeevani
authors.initials: S
authors.lastname: Arora
authors.affiliation: Department of Oncology, Karmanos Cancer Institute, Wayne State University, Detroit, MI, USA.
authors.forename: Joshua
authors.initials: J
authors.lastname: Heyza
authors.affiliation: Department of Oncology, Karmanos Cancer Institute, Wayne State University, Detroit, MI, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Biochemistry & Cancer Biology, University of Toledo Health Science Campus, Toledo, OH, USA.
authors.forename: Vivian
authors.initials: V
authors.lastname: Kalman-Maltese
authors.affiliation: Department of Biochemistry & Cancer Biology, University of Toledo Health Science Campus, Toledo, OH, USA.
authors.forename: Kristin
authors.initials: K
authors.lastname: Tillison
authors.affiliation: Department of Oncology, Karmanos Cancer Institute, Wayne State University, Detroit, MI, USA.
authors.forename: Ashley M
authors.initials: AM
authors.lastname: Floyd
authors.affiliation: Department of Biochemistry & Cancer Biology, University of Toledo Health Science Campus, Toledo, OH, USA.
authors.forename: Elaine M
authors.initials: EM
authors.lastname: Chalfin
authors.affiliation: Department of Oncology, Karmanos Cancer Institute, Wayne State University, Detroit, MI, USA.
authors.forename: Gerold
authors.initials: G
authors.lastname: Bepler
authors.affiliation: Department of Oncology, Karmanos Cancer Institute, Wayne State University, Detroit, MI, USA.
authors.forename: Steve M
authors.initials: SM
authors.lastname: Patrick
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology*; D004260:DNA Repair / Q000187:drug effects*; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors*; D004195:Disease Models, Animal; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D004720:Endonucleases / Q000037:antagonists & inhibitors*; D057166:High-Throughput Screening Assays; D006801:Humans; D020128:Inhibitory Concentration 50; D051379:Mice; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; C095888:xeroderma pigmentosum group F protein; C071447:ERCC1 protein, human; D004720:Endonucleases; D002945:Cisplatin
keywords: DNA repair inhibitor; ERCC1-XPF; chemoresistance; cisplatin; high-throughput screen