RT Journal Article
SR Electronic
T1 Gemcitabine-Induced Activation of Checkpoint Signaling Pathways That Affect Tumor Cell Survival
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 1636
OP 1644
DO 10.1124/mol.105.012716
VO 68
IS 6
A1 Larry M. Karnitz
A1 Karen S. Flatten
A1 Jill M. Wagner
A1 David Loegering
A1 Jennifer S. Hackbarth
A1 Sonnet J. H. Arlander
A1 Benjamin T. Vroman
A1 M. Bijoy Thomas
A1 Yong-Un Baek
A1 Kevin M. Hopkins
A1 Howard B. Lieberman
A1 Junjie Chen
A1 William A. Cliby
A1 Scott H. Kaufmann
YR 2005
UL http://molpharm.aspetjournals.org/content/68/6/1636.abstract
AB Two signaling pathways are activated by antineoplastic therapies that damage DNA and stall replication. In one pathway, double-strand breaks activate ataxia-telangiectasia mutated kinase (ATM) and checkpoint kinase 2 (Chk2), two protein kinases that regulate apoptosis, cell-cycle arrest, and DNA repair. In the second pathway, other types of DNA lesions and replication stress activate the Rad9-Hus1-Rad1 complex and the protein kinases ataxia-telangiectasia mutated and Rad3-related kinase (ATR) and checkpoint kinase 1 (Chk1), leading to changes that block cell-cycle progression, stabilize stalled replication forks, and influence DNA repair. Gemcitabine and cytarabine are two highly active chemotherapeutic agents that disrupt DNA replication. Here, we examine the roles these pathways play in tumor cell survival after treatment with these agents. Cells lacking Rad9, Chk1, or ATR were more sensitive to gemcitabine and cytarabine, consistent with the fact that these agents stall replication forks, and this sensitization was independent of p53 status. Interestingly, ATM depletion sensitized cells to gemcitabine and ionizing radiation but not cytarabine. Together, these results demonstrate that 1) gemcitabine triggers both checkpoint signaling pathways, 2) both pathways contribute to cell survival after gemcitabine-induced replication stress, and 3) although gemcitabine and cytarabine both stall replication forks, ATM plays differential roles in cell survival after treatment with these agents.