Inhibiting Wee1 and ATR kinases produces tumor-selective synthetic lethality and suppresses metastasis
Amirali B. Bukhari, … , Gordon K. Chan, Armin M. Gamper
Amirali B. Bukhari, … , Gordon K. Chan, Armin M. Gamper
Published January 15, 2019
Citation Information: J Clin Invest. 2019;129(3):1329-1344. https://doi.org/10.1172/JCI122622.
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Research Article Oncology

Inhibiting Wee1 and ATR kinases produces tumor-selective synthetic lethality and suppresses metastasis

Abstract

We used the cancer-intrinsic property of oncogene-induced DNA damage as the base for a conditional synthetic lethality approach. To target mechanisms important for cancer cell adaptation to genotoxic stress and thereby to achieve cancer cell–specific killing, we combined inhibition of the kinases ATR and Wee1. Wee1 regulates cell cycle progression, whereas ATR is an apical kinase in the DNA-damage response. In an orthotopic breast cancer model, tumor-selective synthetic lethality of the combination of bioavailable ATR and Wee1 inhibitors led to tumor remission and inhibited metastasis with minimal side effects. ATR and Wee1 inhibition had a higher synergistic effect in cancer stem cells than in bulk cancer cells, compensating for the lower sensitivity of cancer stem cells to the individual drugs. Mechanistically, the combination treatment caused cells with unrepaired or under-replicated DNA to enter mitosis leading to mitotic catastrophe. As these inhibitors of ATR and Wee1 are already in phase I/II clinical trials, this knowledge could soon be translated into the clinic, especially as we showed that the combination treatment targets a wide range of tumor cells. Particularly, the antimetastatic effect of combined Wee1/ATR inhibition and the low toxicity of ATR inhibitors compared with Chk1 inhibitors have great clinical potential.

Authors

Amirali B. Bukhari, Cody W. Lewis, Joanna J. Pearce, Deandra Luong, Gordon K. Chan, Armin M. Gamper

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Figure 3

Contribution of cell cycle phases, during which ATR and/or Wee1 was inhibited, to overall cell killing.

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Contribution of cell cycle phases, during which ATR and/or Wee1 was inhi...
(A and B) AZD6738 and AZD1775 are reversible inhibitors. Immunoblots of MDA-MB-231 and U-2 OS cells treated as indicated. (A) The ATR inhibitor AZD6738 (1 μM) was added to cells 15 minutes before irradiation with 40 J/m2 UV, a strong activator of ATR. One hour after irradiation, AZD6738 was removed and the cells were washed and harvested at indicated times after drug removal. Restoration of ATR activity is observed 1 hour after AZD6738 washout. (B) Cells were incubated for 2 hours with 300 nM Wee1 inhibitor AZD1775, leading to a strong reduction in phospho-CDK1. AZD1775 was then removed and cells washed, leading to restoration of Wee1 activity within 1–2 hours. (C) U-2 OS cells were synchronized by a thymidine-nocodazole block. Six hours after release, cells were treated with 1 μM AZD6738 and/or 300 nM AZD1775. Cell cycle profiles were analyzed by propidium iodide staining and flow cytometry. (D) ATR and/or Wee1 in synchronized cancer cells were transiently inhibited with 1 μM AZD6738 and/or 300 nM AZD1775 during the indicated cell cycle intervals. Survival of drug-treated cells relative to vehicle control was measured after 4 days. Data represent mean ± SD. *P < 0.05, **P < 0.005, and ****P < 0.0001 (one-way ANOVA).