title: Cellular inhibition of checkpoint kinase 2 (Chk2) and potentiation of camptothecins and radiation by the novel Chk2 inhibitor PV1019 [7-nitro-1H-indole-2-carboxylic acid {4-[1-(guanidinohydrazone)-ethyl]-phenyl}-amide].
abstract: Chk2 is a checkpoint kinase involved in the ataxia telangiectasia mutated pathway, which is activated by genomic instability and DNA damage, leading to either cell death (apoptosis) or cell cycle arrest. Chk2 provides an unexplored therapeutic target against cancer cells. We recently reported 4,4'-diacetyldiphenylurea-bis(guanylhydrazone) (NSC 109555) as a novel chemotype Chk2 inhibitor. We have now synthesized a derivative of NSC 109555, PV1019 (NSC 744039) [7-nitro-1H-indole-2-carboxylic acid {4-[1-(guanidinohydrazone)-ethyl]-phenyl}-amide], which is a selective submicromolar inhibitor of Chk2 in vitro. The cocrystal structure of PV1019 bound in the ATP binding pocket of Chk2 confirmed enzymatic/biochemical observations that PV1019 acts as a competitive inhibitor of Chk2 with respect to ATP. PV1019 was found to inhibit Chk2 in cells. It inhibits Chk2 autophosphorylation (which represents the cellular kinase activation of Chk2), Cdc25C phosphorylation, and HDMX degradation in response to DNA damage. PV1019 also protects normal mouse thymocytes against ionizing radiation-induced apoptosis, and it shows synergistic antiproliferative activity with topotecan, camptothecin, and radiation in human tumor cell lines. We also show that PV1019 and Chk2 small interfering RNAs can exert antiproliferative activity themselves in the cancer cells with high Chk2 expression in the NCI-60 screen. These data indicate that PV1019 is a potent and selective inhibitor of Chk2 with chemotherapeutic and radiosensitization potential.
authors.affiliation: Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4255, USA.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Jobson
authors.forename: George T
authors.initials: GT
authors.lastname: Lountos
authors.forename: Philip L
authors.initials: PL
authors.lastname: Lorenzi
authors.forename: Jenny
authors.initials: J
authors.lastname: Llamas
authors.forename: John
authors.initials: J
authors.lastname: Connelly
authors.forename: David
authors.initials: D
authors.lastname: Cerna
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Tropea
authors.forename: Akikazu
authors.initials: A
authors.lastname: Onda
authors.forename: Gabriele
authors.initials: G
authors.lastname: Zoppoli
authors.forename: Sudhir
authors.initials: S
authors.lastname: Kondapaka
authors.forename: Guangtao
authors.initials: G
authors.lastname: Zhang
authors.forename: Natasha J
authors.initials: NJ
authors.lastname: Caplen
authors.forename: John H
authors.initials: JH
authors.lastname: Cardellina
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Yoo
authors.forename: Anne
authors.initials: A
authors.lastname: Monks
authors.forename: Christopher
authors.initials: C
authors.lastname: Self
authors.forename: David S
authors.initials: DS
authors.lastname: Waugh
authors.forename: Robert H
authors.initials: RH
authors.lastname: Shoemaker
authors.forename: Yves
authors.initials: Y
authors.lastname: Pommier
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D001665:Binding Sites; D015153:Blotting, Western; D002166:Camptothecin / Q000494:pharmacology*; D020134:Catalytic Domain; D018929:Cell Culture Techniques; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D064447:Checkpoint Kinase 2; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D005434:Flow Cytometry; D006146:Guanidines / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D006835:Hydrazones / Q000737:chemistry / Q000494:pharmacology*; D051379:Mice; D008958:Models, Molecular; D015394:Molecular Structure; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D011839:Radiation, Ionizing; D011838:Radiation-Sensitizing Agents / Q000737:chemistry / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D020687:cdc25 Phosphatases / Q000378:metabolism
chemical_list: C545735:7-nitro-1H-indole-2-carboxylic acid (4-(1-(guanidinohydrazone)ethyl)phenyl)amide; D000970:Antineoplastic Agents; D006146:Guanidines; D006835:Hydrazones; D047428:Protein Kinase Inhibitors; D011838:Radiation-Sensitizing Agents; D011994:Recombinant Proteins; D064447:Checkpoint Kinase 2; C578634:CHEK2 protein, human; C578633:Chek2 protein, mouse; D017346:Protein Serine-Threonine Kinases; D020687:cdc25 Phosphatases; D002166:Camptothecin