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 4,4Ј-diacetyldiphenylurea-bis(guanylhydrazone) (NSC 109555) as a novel chemotype Chk2 inhibitor. We have now synthesized a derivative of NSC 109555, PV1019 (NSC 744039) 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 radiationinduced 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.

4′-Demethyl-deoxypodophyllotoxin glucoside isolated from Podophyllum hexandrum exhibits potential anticancer activities by altering Chk-2 signaling pathway in MCF-7 breast cancer cells

“…The inhibition constant (Ki) values for compound-5 was 3.2 lM in comparison to the reference compound PV1352, the Ki value of which was 2.8 lM against Chk2 conformer 2YIR. These computer simulated docking results supported the biological activity of compound-5 in modulating checkpoint kinase-2 [37,38].…”

Checkpoint Kinase Inhibitor AZD7762 Overcomes Cisplatin Resistance in Clear Cell Carcinoma of the Ovary

“…20,23 In contrast, a novel small molecule inhibitor of Chk2, PV1019, had a synergistic effect in combination with a topoisomerase I inhibitor in ovarian cancer cells. 24 We observed that simultaneous treatment with si-Chk1 and si-Chk2 dramatically increased sensitivity to cisplatin. Furthermore, recent studies have unveiled several roles for Chk1 in repairing damaged DNA (eg, homologous recombination), negatively regulated mitosis, stabilized stalled replication fork, and inhibited apoptosis.…”

Agonists of the TRAIL Death Receptor DR5 Sensitize Intestinal Stem Cells to Chemotherapy-Induced Cell Death and Trigger Gastrointestinal Toxicity

“…H&E staining of colon isolated at twenty-four (24) hr following treatment with 5-FU and MD5-1 suggested that presence of apoptotic cells by morphology and TUNEL staining following both treatments (Fig. 3A-D).…”

“…5B). Expression profiling of colonic mRNA at twenty-four (24) hr following either CPT-11 or 5-FU revealed the induction of several ‘apoptosis-inducers’ as well as ‘p53-dependent genes’ (Fig. S6A and B).…”