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Suppl. Figures 1-5, Suppl. Table 1 from PARP1 Trapping and DNA Replication Stress Enhance Radiosensitization with Combined WEE1 and PARP Inhibitors

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posted on 2023-04-03, 16:42 authored by Leslie A. Parsels, David Karnak, Joshua D. Parsels, Qiang Zhang, Jonathan Vélez-Padilla, Zachery R. Reichert, Daniel R. Wahl, Jonathan Maybaum, Mark J. O'Connor, Theodore S. Lawrence, Meredith A. Morgan

Supplemental Figure 1: Cytotoxicity by combined WEE1 and PARP inhibition. Supplemental Figure 2: The effects of AZD1775 and olaparib on the radiation-induced G2 checkpoint. Supplemental Figure 3: The effects of AZD1775 and olaparib on RT-mediated γH2AX-staining in lung cancer cells. Supplemental Figure 4: Exogenous nucleosides attenuate AZD1775-induced high-intensity γH2AX staining but do not rescue AZD1775-mediated inhibition of RAD51 focus formation. Supplemental Figure 5: Relative levels of chromatin-bound PARP1 in Calu-6 cells treated with radiation (6 Gy), AZD1775 and either olaparib or veliparib. Supplemental Table 1: The effects of AZD1775 and olaparib on radiosensitization of Calu-6-derived tumor xenografts.

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ARTICLE ABSTRACT

KRAS mutations in non–small cell lung cancer (NSCLC) cause increased levels of DNA damage and replication stress, suggesting that inhibition of the DNA damage response (DDR) is a promising strategy for radiosensitization of NSCLC. This study investigates the ability of a WEE1 inhibitor (AZD1775) and a PARP inhibitor (olaparib) to radiosensitize KRAS-mutant NSCLC cells and tumors. In addition to inhibiting the DDR, these small-molecule inhibitors of WEE1 and PARP induce DNA replication stress via nucleotide exhaustion and PARP trapping, respectively. As monotherapy, AZD1775 or olaparib alone modestly radiosensitized a panel of KRAS-mutant NSCLC lines. The combination of agents, however, significantly increased radiosensitization. Furthermore, AZD1775-mediated radiosensitization was rescued by nucleotide repletion, suggesting a mechanism involving AZD1775-mediated replication stress. In contrast, radiosensitization by the combination of AZD1775 and olaparib was not rescued by nucleosides. Whereas both veliparib, a PARP inhibitor that does not efficiently trap PARP1 to chromatin, and PARP1 depletion radiosensitized NSCLC cells as effectively as olaparib, which does efficiently trap PARP, only olaparib potentiated AZD1775-mediated radiosensitization. Taken together, these mechanistic data demonstrate that although nucleotide depletion is sufficient for radiosensitization by WEE1 inhibition alone, and inhibition of PARP catalytic activity is sufficient for radiosensitization by olaparib alone, PARP1 trapping is required for enhanced radiosensitization by the combination of WEE1 and PARP inhibitors.Implications: This study highlights DNA replication stress caused by nucleotide depletion and PARP1 trapping as an important mechanism of radiosensitization in KRAS-mutant tumors and supports further development of DNA replication as a therapeutic target. Mol Cancer Res; 16(2); 222–32. ©2017 AACR.

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