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目的 对硅转化细胞基因组DNA异常甲基化进行研究 ,探讨硅的表遗传致癌机制。方法 从结晶型硅 (Si)转化BALB/c 3T3细胞中提取基因组DNA ,经Mse1(甲基化非敏感性酶 )单独消化或Mse1和BstU1(甲基化敏感性酶 )联合消化 ,消化产物用甲基化敏感性内切酶指纹法 (MSRF)进行分析 ,差异显示出异常甲基化基因片段 ,进一步将异常甲基化DNA片段亚克隆和序列测定 ,再与基因文库中的基因进行类比分析。结果 发现硅转化细胞存在 6条异常甲基化DNA(其中 1条为高甲基化 ,5条有低甲基化现象 ) ,序列测定显示这些异常甲基化基因片段似乎来源于一些RNA转录和蛋白质翻译等基因家族。结论 DNA异常甲基化会导致基因表达激活或抑制 ,因此硅转化细胞基因组某些功能基因DNA异常甲基化导致的异常表达 ,可能间接是硅诱导细胞转化及其致癌作用的一种表遗传机制
Objective To investigate the abnormal methylation of genomic DNA in silicon-transformed cells and to investigate the epigenetic oncogenic mechanism of silicon. Methods Genomic DNA was extracted from crystalline silicon (Si) transformed BALB / c 3T3 cells and digested with Mse1 (methylation-insensitive enzyme) or with Mse1 and BstU1 (methylation-sensitive enzyme) Methylation-sensitive endonuclease fingerprinting (MSRF) analysis, the difference shows abnormal methylation gene fragments, further subcloning and sequencing of abnormal methylated DNA fragments, and then with the gene library gene analog analysis . As a result, six abnormal methylated DNAs (one of which was hypermethylated and five of which had hypomethylation) were found in the transformed cells of silicon. Sequencing revealed that these abnormal methylated gene fragments appeared to originate from some RNA transcription and protein translation Other gene families. Conclusion Aberrant DNA methylation leads to the activation or inhibition of gene expression. Therefore, aberrant DNA methylation of some functional genes in the genome of silicon-derived transformed cells may indirectly be a epigenetic mechanism of silicon-induced cell transformation and its carcinogenesis