Supplementary Tables S1-S2 from CHK1 Inhibition Synergizes with Gemcitabine Initially by Destabilizing the DNA Replication Apparatus
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posted on 2023-03-30, 23:04 authored by Siang-Boon Koh, Aurélie Courtin, Richard J. Boyce, Robert G. Boyle, Frances M. Richards, Duncan I. Jodrell<p>Supplementary Tables S1-S2. Kinase specificity of S1181 (S1); Percentages of S-phase cells (S2).</p>
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ARTICLE ABSTRACT
Combining cell-cycle checkpoint kinase inhibitors with the DNA-damaging chemotherapeutic agent gemcitabine offers clinical appeal, with a mechanistic rationale based chiefly on abrogation of gemcitabine-induced G2–M checkpoint activation. However, evidence supporting this mechanistic rationale from chemosensitization studies has not been consistent. Here we report a systematic definition of how pancreatic cancer cells harboring mutant p53 respond to this combination therapy, by combining mathematical models with large-scale quantitative biologic analyses of single cells and cell populations. Notably, we uncovered a dynamic range of mechanistic effects at different ratios of gemcitabine and CHK1 inhibitors. Remarkably, effective synergy was attained even where cells exhibited an apparently functional G2–M surveillance mechanism, as exemplified by a lack of both overt premature CDK1 activation and S-phase mitotic entry. Consistent with these findings, S–G2 duration was extended in treated cells, leading to a definable set of lineage-dependent catastrophic fates. At synergistic drug concentrations, global replication stress was a distinct indicator of chemosensitization as characterized molecularly by an accumulation of S-phase cells with high levels of hyperphosphorylated RPA-loaded single-stranded DNA. In a fraction of these cells, persistent genomic damage was observed, including chromosomal fragmentation with a loss of centromeric regions that prevented proper kinetochore-microtubule attachment. Together, our results suggested a “foot-in-the-door” mechanism for drug synergy where cells were destroyed not by frank G2–M phase abrogation but rather by initiating a cumulative genotoxicity that deregulated DNA synthesis. Cancer Res; 75(17); 3583–95. ©2015 AACR.Usage metrics
Keywords
Cell CycleCell cycle checkpointsCell SignalingProtein serine-threonine kinasesChemotherapyCombination chemotherapyDrug MechanismsCell cycle mechanisms of anticancer drug actionCellular responses to anticancer drugsModulation of DNA repairGastrointestinal CancersPancreatic cancerSmall Molecule AgentsDNA-reactive agents
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