ATR functions as a gene dosage-dependent tumor suppressor on a mismatch repair-deficient background.
The ataxia-telangiectasia mutated and rad3-related (ATR) kinase orchestrates cellular responses to DNA damage and replication stress. Complete loss of ATR function leads to chromosomal instability and cell death. However, heterozygous ATR mutations are found in human cancers with microsatellite instability, suggesting that ATR haploinsufficiency contributes to tumorigenesis. To test this possibility, we generated human cell line and mouse model systems in which a single ATR allele was inactivated on a mismatch repair (MMR)-deficient background. Monoallelic ATR gene targeting in MLH1-deficient HCT 116 colon carcinoma cells resulted in hypersensitivity to genotoxic stress accompanied by dramatic increases in fragile site instability, and chromosomal amplifications and rearrangements. The ATR(+/-) HCT 116 cells also displayed compromised activation of Chk1, an important downstream target for ATR. In complementary studies, we demonstrated that mice bearing the same Atr(+/-)/Mlh1(-/-) genotype were highly prone to both embryonic lethality and early tumor development. These results demonstrate that MMR proteins and ATR functionally interact during the cellular response to genotoxic stress, and that ATR serves as a haploinsufficient tumor suppressor in MMR-deficient cells.
Fang
Yanan
Y
Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
Tsao
Cheng-Chung
CC
Goodman
Barbara K
BK
Furumai
Ryohei
R
Tirado
Carlos A
CA
Abraham
Robert T
RT
Wang
Xiao-Fan
XF
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D020137:Base Pair Mismatch / Q000235:genetics*; D002352:Carrier Proteins; D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D043171:Chromosomal Instability; D002869:Chromosome Aberrations; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics*; D005784:Gene Amplification / Q000235:genetics; D018628:Gene Dosage; D005838:Genotype; D006801:Humans; D007621:Karyotyping; D051379:Mice; D000070957:MutL Protein Homolog 1; D009363:Neoplasm Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C501486:MLH1 protein, human; C501485:Mlh1 protein, mouse; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D025521:Tumor Suppressor Proteins; D004247:DNA; C576897:Atr protein, mouse; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D000070957:MutL Protein Homolog 1