Nucleic Acids Research Advance Access originally published online on July 22, 2009
Nucleic Acids Research 2009 37(17):5678-5689; doi:10.1093/nar/gkp593
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Nucleic Acids Research, 2009, Vol. 37, No. 17 5678-5689
© 2009 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Genome Integrity, Repair and Replication |
Inhibition of ATR protein kinase activity by schisandrin B in DNA damage response
1Department of Applied Life Sciences, Niigata University of Pharmacy and Applied Life Sciences, Niigata 956-8603, Japan, 2Department of Biochemistry, Hong Kong University of Science and Technology, Hong Kong, China and 3Department of Cardiology, Baylor College of Medicine, Houston, TX 77030, USA
*To whom correspondence should be addressed. Tel: +81 250 25 5127; Fax: +81 250 25 5127; Email: konishi{at}nupals.ac.jp
Received March 18, 2009. Revised June 29, 2009. Accepted June 29, 2009.
ATM and ATR protein kinases play a crucial role in cellular DNA damage responses. The inhibition of ATM and ATR can lead to the abolition of the function of cell cycle checkpoints. In this regard, it is expected that checkpoint inhibitors can serve as sensitizing agents for anti-cancer chemo/radiotherapy. Although several ATM inhibitors have been reported, there are no ATR-specific inhibitors currently available. Here, we report the inhibitory effect of schisandrin B (SchB), an active ingredient of Fructus schisandrae, on ATR activity in DNA damage response. SchB treatment significantly decreased the viability of A549 adenocarcinoma cells after UV exposure. Importantly, SchB treatment inhibited both the phosphorylation levels of ATM and ATR substrates, as well as the activity of the G2/M checkpoint in UV-exposed cells. The protein kinase activity of immunoaffinity-purified ATR was dose-dependently decreased by SchB in vitro (IC50: 7.25 µM), but the inhibitory effect was not observed in ATM, Chk1, PI3K, DNA-PK, and mTOR. The extent of UV-induced phosphorylation of p53 and Chk1 was markedly reduced by SchB in ATM-deficient but not siATR-treated cells. Taken together, our demonstration of the ability of SchB to inhibit ATR protein kinase activity following DNA damage in cells has clinical implications in anti-cancer therapy.