Pharmacological inactivation of CHK1 and WEE1 induces mitotic catastrophe in nasopharyngeal carcinoma cells
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Joyce P.Y. Mak1, Wing Yu Man1, Jeremy P.H. Chow1, Hoi Tang Ma1, Randy Y.C. Poon1
1Division of Life Science, Center for Cancer Research, and State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong
Randy Y.C. Poon, e-mail: [email protected]
Keywords: DNA damage checkpoint, mitosis, mitotic catastrophe, nasopharyngeal carcinoma, WEE1
Received: March 02, 2015 Accepted: May 09, 2015 Published: May 21, 2015
Nasopharyngeal carcinoma (NPC) is a rare but highly invasive cancer. As radiotherapy is the primary treatment for NPC, this offers a rationale to investigate if uncoupling the DNA damage responses can sensitize this cancer type. The G2 DNA damage checkpoint is controlled by a cascade of protein kinases: ATM/ATR, which phosphorylates CHK1/CHK2, which in turn phosphorylates WEE1. A number of small molecule inhibitors have been developed against these kinases as potential therapeutic agents. Here we demonstrated that compare to that in immortalized nasopharyngeal epithelial cells, ATR, CHK1, and WEE1 were overexpressed in NPC cell lines. Inhibitors of these kinases were unable to promote extensive mitotic catastrophe in ionizing radiation-treated NPC cells, indicating that they are not very effective radiosensitizer for this cancer. In the absence of prior irradiation, however, mitotic catastrophe could be induced with inhibitors against CHK1 (AZD7762) or WEE1 (MK-1775). NPC cells were more sensitive to WEE1 inactivation than nasopharyngeal epithelial cells. Targeting CHK1 and WEE1 together induced more extensive mitotic catastrophe than the individual components alone. Taken together, our results show that NPC cells depend on CHK1 and WEE1 activity for growth and that inhibitors of these kinases may serve as potential therapeutics for NPC.
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