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应用高效液相色谱技术对5-azaCR及MNNG处理的FL、Wish及Vero-E6细胞的DNA中5—甲基胞嘧啶(~mC)含量进行直接测量。结果表明5—aza CR(2×10~(-6)mol/L)处理细胞DNA的~mC含量较对照细胞为低(P<0.01),但在MNNG处理的FL细胞(5×10~(-6)及1×10~(-5)mol/LMNNG)及Wish和Vero-E6细胞(2及3.3×10~(-5)mol/L MNNG)中,DNA的~mC含量与对照并无差异(P>0.05)。这与用HpaⅡ限制性片段长度放射活性分析法检测新复制DNA甲基化状态的结果一致。认为文献中关于细胞DNA低甲基化是化学致癌启动过程普遍规律的结论是由于实验设计的内在缺陷所致。
The contents of 5-methylcytosine (~ mC) in DNA of FL, Wish and Vero-E6 cells treated with 5-azaCR and MNNG were measured by high performance liquid chromatography. The results showed that the ~ mC content of DNA treated with 5-aza CR (2 × 10 -6 mol / L) was lower than that of control cells (P <0.01) -6 and 1 × 10 -5 mol / L MNNG) and Wish and Vero-E6 cells (2 and 3.3 × 10 -5 mol / L MNNG) Difference (P> 0.05). This is consistent with the results of HpaII restriction fragment length radioactivity assay to detect methylation status of newly replicated DNA. It is considered that the literature about the hypomethylation of DNA in cells is the general rule of the initiation of chemical carcinogenesis due to the inherent defects of experimental design.