Research Papers:

Pharmacological targeting the ATR–CHK1–WEE1 axis involves balancing cell growth stimulation and apoptosis

Joyce P.Y. Mak, Wing Yu Man, Hoi Tang Ma and Randy Y.C. Poon _

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Oncotarget. 2014; 5:10546-10557. https://doi.org/10.18632/oncotarget.2508

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Joyce P.Y. Mak1, Wing Yu Man1, Hoi Tang Ma1 and Randy Y.C. Poon1

1 Division 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, email:

Keywords: anticancer drugs; checkpoint; DNA damage; mitosis; mitotic catastrophe

Received: June 14, 2014 Accepted: September 24, 2014 Published: September 25, 2014


The ATR–CHK1–WEE1 kinase cascade’s functions in the DNA damage checkpoints are well established. Moreover, its roles in the unperturbed cell cycle are also increasingly being recognized. In this connection, a number of small-molecule inhibitors of ATR, CHK1, and WEE1 are being evaluated in clinical trials. Understanding precisely how cells respond to different concentrations of inhibitors is therefore of paramount importance and has broad clinical implications. Here we present evidence that in the absence of DNA damage, pharmacological inactivation of ATR was less effective in inducing mitotic catastrophe than inhibition of WEE1 and CHK1. Small-molecule inhibitors of CHK1 (AZD7762) or WEE1 (MK-1775) induced mitotic catastrophe, as characterized by dephosphorylation of CDK1Tyr15, phosphorylation of histone H3Ser10, and apoptosis. Unexpectedly, partial inhibition of WEE1 and CHK1 had the opposite effect of accelerating the cell cycle without inducing apoptosis, thereby increasing the overall cell proliferation. This was also corroborated by the finding that cell proliferation was enhanced by kinase-inactive versions of WEE1. We demonstrated that these potential limitations of the inhibitors could be overcome by targeting more than one components of the ATR–CHK1–WEE1 simultaneously. These observations reveal insights into the complex responses to pharmacological inactivation of the ATR–CHK1–WEE1 axis.

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