Fanconi anemia pathway–deficient tumor cells are hypersensitive to inhibition of ataxia telangiectasia mutated
Richard D. Kennedy, … , Akiko Shimamura, Alan D. D’Andrea
Richard D. Kennedy, … , Akiko Shimamura, Alan D. D’Andrea
Published May 1, 2007
Citation Information: J Clin Invest. 2007;117(5):1440-1449. https://doi.org/10.1172/JCI31245.
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Research Article Oncology

Fanconi anemia pathway–deficient tumor cells are hypersensitive to inhibition of ataxia telangiectasia mutated

Abstract

The Fanconi anemia (FA) pathway maintains genomic stability in replicating cells. Some sporadic breast, ovarian, pancreatic, and hematological tumors are deficient in FA pathway function, resulting in sensitivity to DNA-damaging agents. FA pathway dysfunction in these tumors may result in hyperdependence on alternative DNA repair pathways that could be targeted as a treatment strategy. We used a high-throughput siRNA screening approach that identified ataxia telangiectasia mutated (ATM) as a critical kinase for FA pathway–deficient human fibroblasts. Human fibroblasts and murine embryonic fibroblasts deficient for the FA pathway were observed to have constitutive ATM activation and Fancg–/–Atm–/– mice were found to be nonviable. Abrogation of ATM function in FA pathway–deficient cells resulted in DNA breakage, cell cycle arrest, and apoptotic cell death. Moreover, Fanconi anemia complementation group G– (FANCG-) and FANCC-deficient pancreatic tumor lines were more sensitive to the ATM inhibitor KU-55933 than isogenic corrected lines. These data suggest that ATM and FA genes function in parallel and compensatory roles to maintain genomic integrity and cell viability. Pharmaceutical inhibition of ATM may have a role in the treatment of FA pathway–deficient human cancers.

Authors

Richard D. Kennedy, Clark C. Chen, Patricia Stuckert, Elyse M. Archila, Michelle A. De la Vega, Lisa A. Moreau, Akiko Shimamura, Alan D. D’Andrea

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Figure 4

FA pathway–deficient cells are selectively sensitive to the ATM inhibitor KU-55933.

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FA pathway–deficient cells are selectively sensitive to the ATM inhibito...
(A) Seventy-two-hour dose viability curves comparing the response to KU-55933 for FANCC mutant EUFA426 cells, FANCG mutant EUFA326 cells, FANCD2 mutant PD20 cells, FANCE mutant DF1179 cells, and Fancg–/– MEFs (solid lines) versus isogenic corrected cell lines (dotted lines). (B) Cell cycle profile and 1-hour BRDU uptake in FANCG mutant EUFA326 cells and corrected EUFA326G cells treated with 10 μM KU-55933 for 24 hours or DMSO alone. The x axis represents DNA content (PI staining). Percentages represent proportion of cells in the G1 (2N), S (between 2N and 4N), and G2/M (4N) phases of the cell cycle. (C) An annexin V apoptotic assay comparing FANCG mutant EUFA326 cells with corrected EUFA326G cells treated with 10 μM KU-55933 for 72 hours or DMSO alone. The x axis represents annexin V detection. (D) A clonogenic assay comparing FANCC mutant EUFA426 cells with isogenic corrected cells 14 days after KU-55933 treatment. Lanes 1 and 2 represent untreated controls. Colony counts are given as a percentage of the untreated control for each cell line. (E) Western blot comparing FANCD2 monoubiquitination, ATM autophosphorylation, and H2AX phosphorylation in FANCC mutant EUFA426 cell line (lanes 1 and 3) and isogenic FANCC-corrected cell line (lanes 2 and 4). Lanes 1 and 2 represent an untreated control. Lanes 3 and 4 represent cells treated for 24 hours with 10 μM KU-55933. L/S ratio, ratio between FANCD2-ub band (L) and FANCD2 band (S) as measured by densitometry.