title: Resistance-modifying agents. 9. Synthesis and biological properties of benzimidazole inhibitors of the DNA repair enzyme poly(ADP-ribose) polymerase.
abstract: The nuclear enzyme poly(ADP-ribose) polymerase (PARP) facilitates the repair of DNA strand breaks and is implicated in the resistance of cancer cells to certain DNA-damaging agents. Inhibitors of PARP have clinical potential as resistance-modifying agents capable of potentiating radiotherapy and the cytotoxicity of some forms of cancer chemotherapy. The preclinical development of 2-aryl-1H-benzimidazole-4-carboxamides as resistance-modifying agents in cancer chemotherapy is described. 1H-Benzimidazole-4-carboxamides, particularly 2-aryl derivatives, are identified as a class of potent PARP inhibitors. Derivatives of 2-phenyl-1H-benzimidazole-4-carboxamide (23, K(i) = 15 nM), in which the phenyl ring contains substituents, have been synthesized. Many of these derivatives exhibit K(i) values for PARP inhibition < 10 nM, with 2-(4-hydroxymethylphenyl)-1H-benzimidazole-4-carboxamide (78, K(i) = 1.6 nM) being one of the most potent. Insight into structure-activity relationships (SAR) for 2-aryl-1H-benzimidazole-4-carboxamides has been enhanced by studying the complex formed between 2-(3-methoxyphenyl)-1H-benzimidazole-4-carboxamide (44, K(i) = 6 nM) and the catalytic domain of chicken PARP. Important hydrogen-bonding and hydrophobic interactions with the protein have been identified for this inhibitor. 2-(4-Hydroxyphenyl)-1H-benzimidazole-4-carboxamide (45, K(i) = 6 nM) potentiates the cytotoxicity of both temozolomide and topotecan against A2780 cells in vitro (by 2.8- and 2.9-fold, respectively).
authors.affiliation: Department of Chemistry, Bedson Building, The University, Newcastle upon Tyne NE1 7RU, UK.
authors.forename: A W
authors.initials: AW
authors.lastname: White
authors.forename: R
authors.initials: R
authors.lastname: Almassy
authors.forename: A H
authors.initials: AH
authors.lastname: Calvert
authors.forename: N J
authors.initials: NJ
authors.lastname: Curtin
authors.forename: R J
authors.initials: RJ
authors.lastname: Griffin
authors.forename: Z
authors.initials: Z
authors.lastname: Hostomsky
authors.forename: K
authors.initials: K
authors.lastname: Maegley
authors.forename: D R
authors.initials: DR
authors.lastname: Newell
authors.forename: S
authors.initials: S
authors.lastname: Srinivasan
authors.forename: B T
authors.initials: BT
authors.lastname: Golding
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D001562:Benzimidazoles / Q000138:chemical synthesis* / Q000737:chemistry* / Q000494:pharmacology; D018360:Crystallography, X-Ray; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D008958:Models, Molecular; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D013329:Structure-Activity Relationship; D000077204:Temozolomide; D019772:Topotecan / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: C416381:2-(4-hydroxyphenyl)-1H-benzimidazole-4-carboxamide; D000970:Antineoplastic Agents; D001562:Benzimidazoles; D004791:Enzyme Inhibitors; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D003606:Dacarbazine; D019772:Topotecan; D000077204:Temozolomide