Marsden Carolyn G, Jaruga Pawel, Coskun Erdem, Maher Robyn L, Pederson David S, Dizdaroglu Miral, Sweasy Joann B
Department of Microbiology and Molecular Genetics, The Markey Center for Molecular Genetics, University of Vermont, Burlington, VT 05405, USA.
Present address: Saint Michael's College, Colchester, VT 05439, USA.
Oncotarget. 2020 Jun 16;11(24):2262-2272. doi: 10.18632/oncotarget.27548.
Oxidatively-induced DNA damage, widely accepted as a key player in the onset of cancer, is predominantly repaired by base excision repair (BER). BER is initiated by DNA glycosylases, which locate and remove damaged bases from DNA. NTHL1 is a bifunctional DNA glycosylase in mammalian cells that predominantly removes oxidized pyrimidines. In this study, we investigated a germline variant in the N-terminal domain of NTHL1, R33K. Expression of NTHL1 R33K in human MCF10A cells resulted in increased proliferation and anchorage-independent growth compared to NTHL1 WT-expressing cells. However, wt-NTHL1 and R33K-NTHL1 exhibited similar substrate specificity, excision kinetics, and enzyme turnover and . The results of this study indicate an important function of R33 in BER that is disrupted by the R33K mutation. Furthermore, the cellular transformation induced by R33K-NTHL1 expression suggests that humans harboring this germline variant may be at increased risk for cancer incidence.
氧化诱导的DNA损伤被广泛认为是癌症发生的关键因素，主要通过碱基切除修复（BER）来修复。BER由DNA糖基化酶启动，这些酶定位并从DNA中去除受损碱基。NTHL1是哺乳动物细胞中的一种双功能DNA糖基化酶，主要去除氧化嘧啶。在本研究中，我们研究了NTHL1 N端结构域中的一个种系变体R33K。与表达NTHL1野生型（WT）的细胞相比，在人MCF10A细胞中表达NTHL1 R33K导致增殖增加和不依赖贴壁生长。然而，野生型NTHL1和R33K-NTHL1表现出相似的底物特异性、切除动力学和酶周转率。本研究结果表明R33在BER中具有重要功能，而R33K突变会破坏该功能。此外，R33K-NTHL1表达诱导的细胞转化表明，携带这种种系变体的人患癌症的风险可能会增加。
