鼻咽癌组织中氧化性DNA损伤标志物8-硝基鸟嘌呤和8-羟基脱氧鸟苷的检测及与iNOS的关系

8-硝基鸟嘌呤（8-nitroguanine, 8-NitroG）和8-羟基脱氧鸟苷（8-hydroxy-2′-deoxyguanosine, 8-OHdG）是2个氧化性DNA损伤生物标志物，而诱导型一氧化氮合酶(iNOS)在病理状态下催化细胞合成与氧化性DNA损伤有关的 氧自由基NO.本研究通过检测鼻咽癌组织中8-NitroG、8-OHdG和iNOS的免疫反应强度，初步探究鼻咽癌的发生和发展是否与氧化性DNA损伤有关以及8-NitroG、8-OHdG与iNOS表达的关系.利用多克隆抗体8-NitroG和单克隆抗体8-OHdG、iNOS，采用双色荧光免疫组织化学方法检测鼻咽癌组织中8-NitroG、8-OHdG和iNOS的免疫反应，秩和检验统计学方法分析鼻咽癌和慢性咽炎鼻咽组织之间8-NitroG、8-OHdG和iNOS免疫反应强度的差异.结果显示，19例鼻咽癌组织细胞中，8-NitroG、8-OHdG和iNOS均为强免疫反应，8-NitroG和8-OHdG阳性率100%，iNOS阳性率94.7 %，与13例慢性咽炎组织比较差异显著(P.<0.05).结果提示，鼻咽癌的发生和发展与氧化性DNA损伤有关，其原因与炎症等病理刺激下鼻咽组织高表达的iNOS催化细胞合成氧自由基NO引起的8-NitroG和8-OHdG DNA损伤密切相关.另外，8-NitroG和8-OHdG有望成为辅助鼻咽癌诊断的生物标志物.

Detection of 8-Nitroguanine and 8-Hydroxy-2′-deoxyguanosine, Biomarkers of Oxidative DNA Damage in Nasopharyngeal Carcinoma Tissue and Its Relationship with iNOS

8-nitroguanine (8-NitroG) and 8-hydroxy-2’-deoxyguanosine (8-OHdG) aretwo of the biomarkers for oxidative DNA damage. Inducible nitric oxide synthase(iNOS) catalyze the reaction of cellular nitric oxide (NO) synthesis, which is an oxygen free radical related to oxidative DNA damage at pathological states. To explore whether the origination and development of the nasopharyngeal carcinoma (NPC) are related to oxidative DNA damage, we tested the immune response to 8-NitroG, 8-OHdG in NPC tissues, and analyzed their correlation with iNOS. An anti-8-NitroG polyclonal antibody from rabbit and anti-8-OHdG or anti-iNOS monoclonal antibodies were used in the double immunofluorescent assays to measure the immune response to 8-NitroG, 8-OHdG and iNOS, and the differences of between NPC and pharyngitis chronica (PC) tissues were analyzed with a rank-sum test. The results showed that in the 19 cases of NPC tissue, 100% were detected with substential amount of 8-NitroG or 8-OHdG were positive rate, and 94.7% was detected positive of iNOS. Compared with 13 PC tissues, significant differences (P< 0.05) was observed. It was suggested that the pathological stimulations, such as inflammations from bacteria, virus and parasite in nasopharyngeal tissues, might lead tooxidative DNA lesions by iNOS catalyzed NO, and contribute to the origination and development of NPC. In addition, 8-NitroG and 8-OHdG could be two supportive biomarkers for NPC diagnosis.