ATR inhibitors VE-821 and VX-970 sensitize cancer cells to topoisomerase i inhibitors by disabling DNA replication initiation and fork elongation responses.
Cancer Res
; 74(23): 6968-79, 2014 Dec 01.
Article
em En
| MEDLINE
| ID: mdl-25269479
ABSTRACT
Camptothecin and its derivatives, topotecan and irinotecan, are specific topoisomerase I (Top1) inhibitors and potent anticancer drugs killing cancer cells by producing replication-associated DNA double-strand breaks, and the indenoisoquinoline LMP-400 (indotecan) is a novel Top1 inhibitor in clinical trial. To develop novel drug combinations, we conducted a synthetic lethal siRNA screen using a library that targets nearly 7,000 human genes. Depletion of ATR, the main transducer of replication stress, came as a top candidate gene for camptothecin synthetic lethality. Validation studies using ATR siRNA and the ATR inhibitor VE-821 confirmed marked antiproliferative synergy with camptothecin and even greater synergy with LMP-400. Single-cell analyses and DNA fiber combing assays showed that VE-821 abrogates the S-phase replication elongation checkpoint and the replication origin-firing checkpoint induced by camptothecin and LMP-400. As expected, the combination of Top1 inhibitors with VE-821 inhibited the phosphorylation of ATR and Chk1; however, it strongly induced γH2AX. In cells treated with the combination, the γH2AX pattern changed over time from the well-defined Top1-induced damage foci to an intense peripheral and diffuse nuclear staining, which could be used as response biomarker. Finally, the clinical derivative of VE-821, VX-970, enhanced the in vivo tumor response to irinotecan without additional toxicity. A key implication of our work is the mechanistic rationale and proof of principle it provides to evaluate the combination of Top1 inhibitors with ATR inhibitors in clinical trials.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Compostos Organotiofosforados
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Pirazinas
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Sulfonas
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DNA Topoisomerases Tipo I
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Origem de Replicação
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Replicação do DNA
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Inibidores da Topoisomerase I
Tipo de estudo:
Clinical_trials
Limite:
Humans
Idioma:
En
Revista:
Cancer Res
Ano de publicação:
2014
Tipo de documento:
Article