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Functional Genetic Screen Identifies Increased Sensitivity to WEE1 Inhibition in Cells with Defects in Fanconi Anemia
Marieke Aarts1, Ilirjana Bajrami1, Maria T Herrera-Abreu1
1CRUK Gene Function Laboratory, Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, United Kingdom.
Abstract:
WEE1 kinase regulates CDK1 and CDK2 activity to facilitate DNA replication during S-phase and to prevent unscheduled entry into mitosis. WEE1 inhibitors synergize with DNA-damaging agents that arrest cells in S-phase by triggering direct mitotic entry without completing DNA synthesis, resulting in catastrophic chromosome fragmentation and apoptosis. Here, we investigated how WEE1 inhibition could be best exploited for cancer therapy by performing a functional genetic screen to identify novel determinants of sensitivity to WEE1 inhibition. Inhibition of kinases that regulate CDK activity, CHK1 and MYT1, synergized with WEE1 inhibition through both increased replication stress and forced mitotic entry of S-phase cells. Loss of multiple components of the Fanconi anemia (FA) and homologous recombination (HR) pathways, in particular DNA helicases, sensitized to WEE1 inhibition. Silencing of FA/HR genes resulted in excessive replication stress and nucleotide depletion following WEE1 inhibition, which ultimately led to increased unscheduled mitotic entry. Our results suggest that cancers with defects in FA and HR pathways may be targeted by WEE1 inhibition, providing a basis for a novel synthetic lethal strategy for cancers harboring FA/HR defects.
Insights
WEE1 inhibitors can be a potent cancer therapy, especially when combined with therapies targeting DNA repair defects. This approach exploits synthetic lethality in cancers with Fanconi anemia (FA) or homologous recombination (HR) pathway deficiencies.
Area of Science:
- Cellular biology
- Molecular oncology
- Cancer genetics
Background:
- WEE1 kinase is crucial for regulating cell cycle progression, specifically DNA replication during S-phase and preventing premature entry into mitosis.
- WEE1 inhibitors show promise in cancer therapy, particularly when combined with DNA-damaging agents, by inducing mitotic catastrophe in cancer cells.
Purpose of the Study:
- To identify novel genetic determinants of sensitivity to WEE1 inhibition for optimizing cancer therapy.
- To explore the synergistic effects of inhibiting WEE1 with other cell cycle regulators and DNA repair pathways.
Main Methods:
- Functional genetic screening to identify WEE1 inhibitor sensitivity determinants.
- Investigating the impact of inhibiting CHK1 and MYT1 kinases alongside WEE1 inhibition.
- Analyzing the effects of silencing Fanconi anemia (FA) and homologous recombination (HR) pathway genes on WEE1 inhibition sensitivity.
Main Results:
- Inhibition of CHK1 and MYT1 kinases synergized with WEE1 inhibition, increasing replication stress and forcing S-phase cells into mitosis.
- Loss of FA and HR pathway components, including DNA helicases, significantly sensitized cells to WEE1 inhibition.
- Silencing FA/HR genes led to replication stress and nucleotide depletion upon WEE1 inhibition, promoting unscheduled mitotic entry.
Conclusions:
- WEE1 inhibition represents a potential therapeutic strategy for cancers with defects in the Fanconi anemia (FA) and homologous recombination (HR) pathways.
- This study provides a basis for a novel synthetic lethal approach targeting cancers with FA/HR deficiencies through WEE1 inhibition.
