苯并a芘诱发细胞恶性转化过程中基因组总体DNA甲基化改变
Genomic DNA Methylation in Benzo(a) pyrene-Induced Cell Malignant Transformation
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摘要:
目的 观察苯并a芘(BaP)诱导人支气管上皮细胞(16HBE)恶性转化过程中基因组总体DNA甲基化水平的改变。 方法 采用40.0μmol/L BaP长期诱导16HBE细胞,构建恶性转化细胞模型,分别采用5-甲基胞嘧啶免疫荧光和高效毛细管电泳技术从定性和定量的角度动态检测细胞全基因组总体DNA甲基化水平的变化趋势,同时监测DNA甲基转移酶的活性改变。 结果 在BaP诱导16HBE细胞3、6、9、12、15及18周过程中,细胞基因组DNA总体甲基化水平呈时间依赖性降低;定量分析结果显示,正常16HBE细胞基因组DNA总体甲基化百分比(mCpG%)为(4.78& #177;0.58)%,各诱导阶段细胞的mCpG%值分别为(4.62& #177;0.39)%、(3.82& #177;0.39)%、(4.07& #177;0.40)%、(3.27& #177;0.31)%、(2.63& #177;0.21)%和(2.48& #177;0.15)%。随着诱导时间的延长, 16HBE细胞中总体甲基转移酶活性也呈逐渐降低的趋势。 结论 基因组总体DNA甲基化水平进行性降低是BaP诱导16HBE细胞恶性转化过程中的重要特征, DNA甲基转移酶活性的降低是导致细胞基因组DNA总体甲基化水平降低的主要原因。 Abstract:Objective To observe the changes in genomic DNA methylation profile of benzo(a)pyrene (BaP)-induced malignant transformation of human bronchial epithelial cells (16HBE). Methods A malignant transformed 16HBE model was established by 40.0 μmol/L BaP administration. The dynamic cellular genome DNA methylation levels were qualitatively and quantitatively detected by 5-methylcytosine immunofluorescence and high-performance capillary electrophoresis, respectively. The DNA methyltransferase activity was also monitored. Results At the selected time spots of 3, 6, 9, 12, 15, and 18 weeks during the 16HBE malignant transformation induced by BaP, the genomic DNA methylation levels decreased in a time-dependent manner, and the genomic DNA methylation percentages (mCpG%) at corresponding time spots were (4.62& #177;0.39)%, (3.82& #177;0.39)%, (4.07& #177;0.40)%, (3.27& #177;0.31)%, (2.63& #177;0.21)% and (2.48& #177;0.15)% respectively, while the mCpG% of the normal 16HBE cells was (4.78& #177;0.58)%. In addition, the methyltransferase activities of the BaP-treated 16HBE cells also decreased in a time-dependent manner. Conclusion The reduced genomic DNA methylation level is an important feature in the process of BaP-induced malignant transformation of 16HBE cells, and the reduced DNA methyltransferase activity is the main cause.
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