crc-23-0306_fig3.png (1.22 MB)

FIGURE 3 from FBXW7-loss Sensitizes Cells to ATR Inhibition Through Induced Mitotic Catastrophe

figure

posted on 2023-12-21, 14:20 authored by Siobhan O'Brien, Tajinder Ubhi, Lucie Wolf, Krishna Gandhi, Sichun Lin, Naz Chaudary, Neesha C. Dhani, Michael Milosevic, Grant W. Brown, Stephane Angers

Cells harboring FBXW7 mutations have enhanced sensitivity to AZD6738. A, Dose–response assay using AZD6738 in HPAF-II wild-type and FBXW7⁻^/⁻, representative of three replicates, mean ± SEM. B, Clonogenic growth assay in HPAF-II wild-type and FBXW7⁻^/⁻, representative images of three replicates. C, Quantification of clonogenic growth assays, n = 3, mean ± SEM, two-way ANOVA. D, Dose–response assay of cervical cancer cells C33A (FBXW7^R465H), SiHa and Caski (both FBXW7^WT), representative of three replicates, mean ± SEM. E, Clonogenic growth assays in a cervical cancer cell line panel, representative images of three replicates. F, Quantification of clonogenic growth assays, n = 3, mean ± SEM, two-way ANOVA. G, AZD6738 sensitivity data from The Cancer Dependency Map (DepMap, Broad Institute) in cancers that harbor high rates of FBXW7 alterations; cervical cancer, uterine cancer, and colorectal cancer. Mean ± SEM, unpaired t test, **, P < 0.01.

Funding

Gouvernement du Canada | Canadian Institutes of Health Research (IRSC)

CCS | Canadian Cancer Society Research Institute (CCSRI)

History

ARTICLE ABSTRACT

FBXW7 is a commonly mutated tumor suppressor gene that functions to regulate numerous oncogenes involved in cell-cycle regulation. Genome-wide CRISPR fitness screens identified a signature of DNA repair and DNA damage response genes as required for the growth of FBXW7-knockout cells. Guided by these findings, we show that FBXW7-mutant cells have high levels of replication stress, which results in a genotype-specific vulnerability to inhibition of the ATR signaling pathway, as these mutant cells become heavily reliant on a robust S–G2 checkpoint. ATR inhibition induces an accelerated S-phase, leading to mitotic catastrophe and cell death caused by the high replication stress present in FBXW7−/− cells. In addition, we provide evidence in cell and organoid studies, and mining of publicly available high-throughput drug screening efforts, that this genotype-specific vulnerability extends to multiple types of cancer, providing a rational means of identifying responsive patients for targeted therapy. We have elucidated the synthetic lethal interactions between FBXW7 mutation and DNA damage response genes, and highlighted the potential of ATR inhibitors as targeted therapies for cancers harboring FBXW7 alterations.