title: Development of Small Molecules that Specifically Inhibit the D-loop Activity of RAD51.
abstract: RAD51 is the central protein in homologous recombination (HR) DNA repair and represents a therapeutic target in oncology. Herein we report a novel class of RAD51 inhibitors that were identified by high throughput screening. In contrast to many previously reported RAD51 inhibitors, our lead compound 1 is capable of blocking RAD51-mediated D-loop formation (IC50 21.3 ± 7.8 μM) at concentrations that do not influence RAD51 binding to ssDNA. In human cells, 1 inhibits HR (IC50 13.1 ± 1.6 μM) without blocking RAD51's ability to assemble into subnuclear foci at sites of DNA damage. We determined that the active constituent of 1 is actually an oxidized derivative (termed RI(dl)-1 or 8) of the original screening compound. Our SAR campaign also yielded RI(dl)-2 (hereafter termed 9h), which effectively blocks RAD51's D-loop activity in biochemical systems (IC50 11.1 ± 1.3 μM) and inhibits HR activity in human cells (IC50 3.0 ± 1.8 μM).
authors.affiliation: Department of Medicinal Chemistry and Pharmacognosy, Drug Discovery Program, University of Illinois at Chicago , Chicago, 833 South Wood Street 539c PHAR, MC 781, Illinois 60612, United States.
authors.forename: Wei
authors.initials: W
authors.lastname: Lv
authors.affiliation: Department of Radiation and Cellular Oncology, University of Chicago , Chicago, Illinois 60637, United States.
authors.forename: Brian
authors.initials: B
authors.lastname: Budke
authors.affiliation: Department of Medicinal Chemistry and Pharmacognosy, Drug Discovery Program, University of Illinois at Chicago , Chicago, 833 South Wood Street 539c PHAR, MC 781, Illinois 60612, United States.
authors.forename: Michal
authors.initials: M
authors.lastname: Pawlowski
authors.affiliation: Department of Radiation and Cellular Oncology, University of Chicago , Chicago, Illinois 60637, United States.
authors.forename: Philip P
authors.initials: PP
authors.lastname: Connell
authors.affiliation: Department of Medicinal Chemistry and Pharmacognosy, Drug Discovery Program, University of Illinois at Chicago , Chicago, 833 South Wood Street 539c PHAR, MC 781, Illinois 60612, United States.
authors.forename: Alan P
authors.initials: AP
authors.lastname: Kozikowski
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015394:Molecular Structure; D051135:Rad51 Recombinase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D054852:Small Molecule Libraries / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D054852:Small Molecule Libraries; C495153:RAD51 protein, human; D051135:Rad51 Recombinase