Low Grace Kah Mun, Fok Edwin Dan Zhihao, Ting Aloysius Poh Leong, Hande M Prakash
Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, MD9, 2 Medical Drive, Singapore 117597, Singapore.
Int J Biochem Cell Biol. 2008;40(11):2583-95. doi: 10.1016/j.biocel.2008.05.009. Epub 2008 May 21.
Xeroderma Pigmentosum A protein plays a pivotal role in the nucleotide excision repair pathway. Through site-directed binding of rigidly kinked double-stranded DNA, it verifies damaged DNA for subsequent excision and incision. Although Xeroderma Pigmentosum A-deficient cells have shown to be defective in oxidative base-lesion repair, the effects of oxidative assault on such cells have not been fully explored. Therefore, we sought to determine the involvement of Xeroderma Pigmentosum A in oxidative DNA damage-repair by treating primary fibroblasts from a patient suffering from Xeroderma Pigmentosum A with sodium arsenite and hydrogen peroxide. Our results show dose-dependent increase in genotoxicity with little change in cytotoxicity with both arsenite and H2O2 in Xeroderma Pigmentosum A-deficient cells compared to control cells. Xeroderma Pigmentosum A-deficient cells displayed increased susceptibility and reduced repair capacity when subjected to DNA damage induced by oxidative stress. Superarray results of apoptotic genes revealed differential expression of approximately 10 genes between Xeroderma Pigmentosum A-deficient and normal cells following arsenite treatment. Interestingly, we noted that arsenite did not inflict as much damage in the cells compared to H2O2. Lack of functional Xeroderma Pigmentosum A seems to increase the susceptibility of oxidative stress-induced genotoxicity while retaining cell viability posing as a potential cancer risk factor of Xeroderma Pigmentosum A patients.
着色性干皮病A蛋白在核苷酸切除修复途径中起关键作用。通过与严重扭结的双链DNA进行定点结合,它可识别受损DNA以便后续切除和切割。尽管已表明着色性干皮病A缺陷细胞在氧化碱基损伤修复方面存在缺陷,但氧化攻击对这类细胞的影响尚未得到充分研究。因此,我们试图通过用亚砷酸钠和过氧化氢处理一名着色性干皮病A患者的原代成纤维细胞,来确定着色性干皮病A在氧化DNA损伤修复中的作用。我们的结果显示,与对照细胞相比,在着色性干皮病A缺陷细胞中,亚砷酸盐和过氧化氢均导致遗传毒性呈剂量依赖性增加,而细胞毒性变化不大。当受到氧化应激诱导的DNA损伤时,着色性干皮病A缺陷细胞表现出更高的敏感性和更低的修复能力。凋亡基因的超级阵列结果显示,亚砷酸盐处理后,着色性干皮病A缺陷细胞和正常细胞之间约有10个基因存在差异表达。有趣的是,我们注意到与过氧化氢相比,亚砷酸盐对细胞造成的损伤较小。缺乏功能性着色性干皮病A似乎会增加氧化应激诱导的遗传毒性的易感性,同时保持细胞活力,这成为着色性干皮病A患者潜在的癌症风险因素。