反式二羟环氧苯并(a)芘-DNA加合物在肺癌发病中的作用

Study on the Role of BPDE-DNA Adducts in Development of Human Lung Cancer

[目的]反式二羟环氧苯并 (a)芘 (BPDE)为苯并 (a)芘在体内的代谢产物 ,是一种直接的致癌物 ,可攻击DNA形成BPDE_DNA加合物 ,本研究目的为探明该加合物在人群肺癌发生中的作用及其分子机制。[方法]使用针对BPDE_DNA加合物的单克隆抗体 ,通过免疫学方法检测150例肺癌、120例癌旁肺组织、40例肺良性病变和40例正常肺组织中BPDE_DNA加合物的含量 ,同时检测相应肺组织中P53、C_MYC、K_ras、BCL_2、hTERT等癌变相关基因的表达 ,分析BPDE_DNA加合物与上述基因的关系。并在BPDE诱导的体外人气管上皮细胞癌变模型上检测癌变过程中BPDE_DNA加合物的变化。[结果]82.0 % (123/150)的肺癌组织 ,37.5 % (45/120)的癌旁肺组织 ,15.0% (6/40)的肺良性病变和2.5% (1/40)的正常肺组织可检出BPDE_DNA加合物 ,肺癌组织中加合物的含量显著高于其他肺组织 ,P<0.01。分层分析发现男性肺癌病例加合物检出率为89.9% (107/119)高于女性的检出率51.6 % (16/31) ,P<0.05。有吸烟史的肺癌患者加合物检出率为99.1% (113/114)高于非吸烟肺癌患者的27.8% (10/36),P<0.01。肺癌组织P53、K_ras、BCL_2基因的阳性表达与BPDE_DNA加合物有关联 ,而C_MYC、hTERT基因的表达与BPDE_DNA加合物无关联。在体外用BPDE作用于人气管上皮细胞系 ,可诱导?

anti_benzo(a)pyrene diol_epoxide(BPDE),the metabolite of benzopyrene,is a strong direct carcinogen and can induce BPDE_DNA adduct. To investigate the role of BPDE_DNA adducts in the development of human lung cancer and its molecular mechanism of carcinogenesis. A BPDE_DNA_specific monoclonal antibody and biotin_streptavidin immuno_staining were used to detect the BPDE_induced DNA adducts in 150 specimens of human lung cancer tissues,120 lung tissues adjacent to cancer foci without cancer cells,40 specimens of tissue with benign lung lesions and 40 normal lung tissues. The protein expression of P53,C_MYC,K_ras,BCL_2 and hTERT (human telomerase reverse transcriptase) in lung tissues was assessed by immuno_histochemical methods. The relationships between the BPDE_DNA adduct formation and these genes were analyzed. The BPDE_DNA adducts were also determined during the process of carcnogenesis in human bronchial epithelial cells induced by BPDE in vitro. The BPDE_DNA adducts were positive in 123 of 150(82.0%) lung cancer foci specimens,in 45 of 120(37.5%) lung tissues adjacent to cancer foci without cancer cells,in 6 of 40(15.0%) tissues with benign lung lesions,whereas only 1 of 40(2.5%) normal lung tissues was weakly positive with adducts. The level of BPDE_DNA adduct in lung cancer foci tissues was significantly higher than that of adjacent lung tissues,tissues with benign lung lesions and normal lung tissues,P<0.001. Stratified the lung cancer patients by sex,age,cell types and smoking history,the positive rate of BPDE_DNA adduct detection was higher in males than that in females,89.9%(107/119) versus 51.6%(16/31),P<0.05. Adducts in smokers were higher than those in nonsmokers,113 of 114(99.1%) versus 10 of 36(27.8%),P<0.01. Over_expression of P53,K_ras and BCL_2 in lung cancer FOCI tissues were associated with the BPDE_DNA adduct levels,but the expression of C_MYC and hTERT were not. In vitro,the malignant transformation and carcinogenesis of human bronchial epithelial cells were induced by BPDE. During the process of carcinogenesis in vitro,the BPDE_DNA adducts were determined from negative to strong positive. [Conclusion] BPDE_DNA adduct was an important biomarker which may reflect the exposure and cancer_inducing effect of B(a)P. And BPDE_DNA adduct might associate with P53,K_ras,and BCL_2 genes in the carcinogenesis.