ATR functions as a gene dosage-dependent tumor suppressor on a mismatch repair-deficient background
ATR functions as a gene dosage-dependent tumor suppressor on a mismatch repair-deficient background
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DOI：
10.1038/sj.emboj.7600315
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发表时间：
2004-08-04
期刊：
影响因子：
11.4
通讯作者：
Wang, XF
中科院分区：
文献类型：
--
作者：
Fang, Y;Tsao, CC;Wang, XF
共济失调-毛细血管扩张突变和Rad3相关(ATR)激酶协调细胞对DNA损伤和复制应激的反应。ATR功能的完全丧失会导致染色体不稳定和细胞死亡。然而，在具有微卫星不稳定性的人类癌症中发现了ATR杂合突变，这表明ATR单倍体不足与肿瘤的发生有关。为了测试这种可能性，我们建立了人类细胞系和小鼠模型系统，在这些系统中，单个ATR等位基因在错配修复(MMR)缺陷的背景下失活。在MLH1缺失的HCT 116结肠癌细胞中，单等位ATR基因靶向导致了对遗传毒性应激的超敏，并伴随着脆性位点不稳定性以及染色体扩增和重排的急剧增加。ATR(+/-)Hct 116细胞也显示出Chk1的激活受损，Chk1是ATR的一个重要下游靶点。在补充性研究中，我们证明了携带相同ATR(+/-)/MLH1(-/-)基因的小鼠极易导致胚胎死亡和早期肿瘤发展。这些结果表明，在细胞对遗传毒性应激的反应中，MMR蛋白和ATR在功能上相互作用，在MMR缺陷细胞中，ATR是一种单倍体不足的肿瘤抑制因子。
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.