Effects of pH on nicotine-induced DNA damage and oxidative stress
Effects of pH on nicotine-induced DNA damage and oxidative stress
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DOI：
10.1080/15287390590967478
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发表时间：
2005-09-01
影响因子：
2.6
通讯作者：
Liu, TY
中科院分区：
文献类型：
--
作者：
Wu, HJ;Chi, CW;Liu, TY
流行病学证据显示嚼槟榔液与吸烟对台湾口腔鳞状细胞癌的发展有协同作用。咀嚼槟榔液会使唾液碱化。本研究通过单细胞凝胶电泳检测尼古丁对DNA损伤的影响，研究了不同pH环境（6.5和8）下人类口腔癌OEC-M1细胞对尼古丁的反应。尼古丁（1 μ M和10 μ M）在pH 8条件下培养6 h显著诱导DNA链断裂，而在pH 6.5条件下不诱导DNA链断裂。尼古丁引起的DNA损伤也有时间依赖性。当细胞用过氧化氢酶或n -乙酰半胱氨酸预处理时，观察到尼古丁诱导的DNA损伤显著减少。流式细胞分析显示，尼古丁（10 μ M）处理后，8-氧鸟嘌呤的产量显著增加。用核酸内切酶III和甲脒嘧啶-DNA糖基酶处理尼古丁损伤的DNA，识别氧化的DNA碱基，增加了DNA损伤的程度。这些结果表明，尼古丁诱导的DNA链断裂是pH依赖性的，氧化应激可能参与尼古丁诱导的DNA损伤。最后，香烟烟雾冷凝水（相当于8 μ M尼古丁）在pH为8时诱导OEC-M1细胞显著的DNA链断裂，并与DNA氧化损伤的产生相关。因此，咀嚼槟榔液产生的碱性唾液在香烟相关的尼古丁诱导的DNA损伤中起重要作用，活性氧可能参与了这种DNA损伤的产生。
Epidemiological evidence suggests that chewing betel quid and smoking have synergistic potential in the development of oral squamous-cell carcinoma in Taiwan. Chewing betel quid produces alkalization of saliva. This study investigated the response of human oral cancer OEC-M1 cells to nicotine in different pH environments (6.5 and 8) by examining its effects on DNA damage as evidenced by single-cell gel electrophoresis. Nicotine (1 and 10,mu M) significantly induced DNA strand breakage when cultured at pH 8 for 6 h but did not induce DNA damage at pH 6.5. Nicotine-induced DNA damage was also time dependent. When cells were pretreated with catalase or N-acetylcysteine, a significant reduction in nicotine-induced DNA damage was observed. Flow cytometric analyses showed that the production of 8-oxoguanine was significantly increased following nicotine (10 mu M) treatment. Posttreatment of nicotine-damaged DNA by endonuclease III and formamidopyrimidine-DNA glycosylase, recognizing oxidized DNA bases, increased the extent of DNA damage. These results suggest that nicotine-induced DNA strand breakage is pH dependent, and oxidative stress might be involved in nicotine-induced DNA damage. Finally, cigarette smoke condensate (equivalent to 8 mu M nicotine) induced significant DNA strand breaks in OEC-M1 cells at pH 8 and correlated with the generation of oxidative DNA damage. Thus, alkaline saliva generated by chewing betel quid plays an important role in cigarette-related nicotine-induced DNA damage, and reactive oxygen species may be involved in generating this DNA damage.