Irofulven induces replication-dependent CHK2 activation related to p53 status

• Published in: Biochemical pharmacology 2007-02, Vol.73 (4), p.469-480
• Main Authors: Wang, Yutian, Wiltshire, Timothy, Senft, Jamie, Reed, Eddie, Wang, Weixin
• Format: Article
• Language: English
• Subjects: Antineoplastic Agents, Alkylating - pharmacology; Biological and medical sciences; Blotting, Western; Cell cycle; Cell Line, Tumor; Checkpoint Kinase 2; Chemosensitivity; CHK2; Chromosome Aberrations - chemically induced; DNA Replication - drug effects; DNA, Neoplasm - antagonists & inhibitors; DNA, Neoplasm - biosynthesis; Dose-Response Relationship, Drug; Enzyme Activation - drug effects; Flow Cytometry; G1 Phase - drug effects; G2 Phase - drug effects; HCT116 Cells; Histones - metabolism; Humans; Irofulven; Medical sciences; p53; Pharmacology. Drug treatments; Phosphorylation - drug effects; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Replication; S Phase - drug effects; Sesquiterpenes - pharmacology; Tumor Suppressor Protein p53 - metabolism
• ISSN: 0006-2952; 1873-2968
• DOI: 10.1016/j.bcp.2006.10.023

CHK2 and p53 are frequently mutated in human cancers. CHK2 is known to phosphorylate and stabilize p53. CHK2 has also been implicated in DNA repair and apoptosis induction. However, whether p53 affects CHK2 activation and whether CHK2 activation modulates chemosensitivity are unclear. In this study, we found that in response to the DNA damage agent, irofulven, CHK2 activation, rather than its expression, is inversely correlated to p53 status. Irofulven inhibits DNA replication and induces chromosome aberrations (breaks and radials) and p53-dependent cell cycle arrest. Pretreatment of cells with the DNA polymerase inhibitor, aphidicolin, resulted in reduction of irofulven-induced CHK2 activation and foci formation, indicating that CHK2 activation by irofulven is replication-dependent. Furthermore, by using ovarian cancer cell lines expressing dominant-negative CHK2 and CHK2-knockout HCT116 cells, we found that CHK2 activation contributes to the control of S and G2/M cell cycle arrests, but not chemosensitivity to irofulven. Overall, this study demonstrates that in response to irofulven-induced DNA damage, the activation of CHK2 is dependent on DNA replication and related to p53 status. By controlling cell cycle arrest and DNA replication, p53 affects CHK2 activation. CHK2 activation contributes to cell cycle arrest, but not chemosensitivity.