Wee1 Kinase Inhibitor AZD1775 Radiosensitizes Hepatocellular Carcinoma Regardless of TP53 Mutational Status Through Induction of Replication Stress

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• 作者：Kyle C. Cuneo ; MD ; ^{kcuneo@umich.edu" class="auth_mail" title="E-mail the corresponding author} ; Meredith A. Morgan ; PhD ; Mary A. Davis ; PhD ; Leslie A. Parcels ; PhD ; Joshua Parcels ; BS ; David Karnak ; PhD ; Caila Ryan ; Na Liu ; BS ; Jonathan Maybaum ; PhD ; Theodore S. Lawrence ; MD ; PhD
• 刊名：International Journal of Radiation Oncology*Biology*Physics
• 出版年：2016
• 出版时间：1 June 2016
• 年：2016
• 卷：95
• 期：2
• 页码：782-790
• 全文大小：1313 K

文摘

Wee1 kinase inhibitors are effective radiosensitizers in cells lacking a G₁ checkpoint. In this study we examined the potential effect of Wee1 kinase inhibition on inducing replication stress in hepatocellular carcinoma (HCC).

Methods and Materials

Five independent datasets from the Oncomine database comparing gene expression in HCC compared to normal tissue were combined and specific markers associated with Wee1 sensitivity were analyzed. We then performed a series of in vitro experiments to study the effect of Wee1 inhibition on irradiated HCC cell lines with varying p53 mutational status. Clonogenic survival assays and flow cytometry using anti-γH2AX and phospho-histone H3 antibodies with propidium iodide were performed to study the effect of AZD1775 on survival, cell cycle, and DNA repair. Additionally, nucleoside enriched medium was used to examine the effect of altering nucleotide pools on Wee1 targeted radiation sensitization.

Results

Our analysis of the Oncomine database found high levels of CDK1 and other cell cycle regulators indicative of Wee1 sensitivity in HCC. In our in vitro experiments, treatment with AZD1775 radiosensitized and chemosensitized Hep3B, Huh7, and HepG2 cell lines and was associated with delayed resolution of γH2AX foci and the induction of pan-nuclear γH2AX staining. Wee1 inhibition attenuated radiation-induced G₂ arrest in the Hep3B (TP53 null) and Huh7 (TP53 mutant) cell lines but not in the TP53 wild-type cell line HepG2. Supplementation with nucleosides reversed the radiation-sensitizing effect of AZD1775 and reduced the amount of cells with pan-nuclear γH2AX staining after radiation.

Conclusions

Radiation sensitization with Wee1 inhibition occurs in cells regardless of their p53 mutational status. In this study we show for the first time that replication stress via the overconsumption of nucleotides plays an important role in AZD1775-induced radiation sensitization.