中文摘要：

目的检测经长期氡暴露而发生恶性转化的人永生化支气管上皮细胞（BEAS-2B）中甲基化转移酶（DNMT）基因的动态变化,从表观遗传学层面探索氡致肺癌的作用机制。方法应用流式细胞仪分析法,软琼脂集落形成及裸鼠成瘤实验鉴定长期氡暴露过程中BEAS-2B细胞的恶性转化程度,以QPCR方法检测DNMT1、DNMT3A的mRNA表达量。结果与对照组细胞相比,染氡30代传代至40代的细胞软琼脂克隆形成率已升高至27.27%±1.10%（P〈0.05）,转化细胞在裸鼠体内成瘤率达到30%（P〈0.05）,呈低分化癌;QPCR结果显示各染氡组传至40代细胞DNMT1 mRNA表达量均低于对照组,DNMT3A mRNA表达量均高于对照组。结论建立并确认了体外染氡诱发BEAS-2B细胞恶性转化模型,且细胞恶性程度随染氡代数和传代代数的增加呈现剂量-效应关系,细胞出现移植成瘤。本试验条件下,DNMTs表达的改变导致细胞增殖失控,打破内环境平衡,这可能是在表观遗传学中,长期氡暴露致BEAS-2B细胞恶性转化的机制之一。

英文摘要：

Objective To explore the mechanism of radon-induced lung cancer from epigenetic level by detecting the dynamic change methylation transferase（ DNMT） gene in malignant transformed immortalized human bronchial epithelial cells（ BEAS-2B） in the process of long-term radon exposure. Methods The malignant degrees of transformed cells were identified by flow cytometry analysis,anchorage independent growth and tumorigenicity. The mRNA expression of DNMT1 and DNMT3 A were detected by QPCR. Results The capacity of colony formation rate was up to 27. 27% ± 1. 10% in soft ager after exposure for 30 passages and generation to 40 th passage significantly higher compared to control group（ P〈0. 05）. Pathology analysis revealed that tumor cells with different sizes were distributed diffusely. The mRNA level of DNMT1 gene was higher in the control group than that in the exposure group. The DNMT3 A gene expression was lower in the control group than that in the exposure group. Conclusions A model of malignant transformation of human cells in vitro induced by radon was established and transplanted tumors were formed in nude mice. The degree of malignancy had a dose-dependent relationship with the exposure and generation passages. Under the experimental conditions,changes in DNMTs expression led to uncontrolled cell proliferation and environmental disturbance,this may be the mechanism of radon-induced lung cancer.