目的 脑胶质母细胞瘤(glioblastoma,GBM)中存在广泛的基因组低甲基化,本研究检查了DNA甲基化转移酶3B (DNA methyltransferase 3B,DMNT3B)是否在这种肿瘤中的表达和突变情况,以期寻找肿瘤基因组低甲基化发生的原因.方法 用RNA抽提试剂盒从 25例人脑胶质母细胞瘤组织中提取总RNA,用反转录聚合酶链反应方法扩增DNMT3B 的cDNA,然后测序,所得序列经DNASTAR软件与NCBI发表的正常序列进行比对.结果从25例脑胶质母细胞瘤样本中的成功扩增了全长DNMT3B cDNA,测序分析结果显示DNMT3B基因在该肿瘤样本中差异性存在多种剪接变异体,以DNMT3B-V1、DNMT3B-V3、DNMT3B-V7为主.没有发现改变氨基酸序列的点突变.结论 DNMT3B基因在脑胶质母细胞瘤中没有点突变,但存在多种剪接变异体(以DNMT3B-V3、DNMT3B-V7为主),其是否为脑胶质母细胞瘤的广泛基因组低甲基化的原因尚有待进一步研究.%Objective Global genomic hypomethylation widely exists in glioblastoma ( GBM). This study aimed to clarify the molecular mechanism of this abnormality. Methods Totally 25 GBM samples were examined in this study. Total RNA was extracted from these patient samples. Full-length cDNA was amplified by RT - PCR and sequenced. Sequences obtained from each sample were compared to NCBI published standard sequences by using DNASTAR software. Results We successfully amplified DNMT3B from each patient sample. No point mutation which alters amino acids was identified. But several splicing variants were identified in these patient samples which were differentially exited in the tumor samples. Conclusion No point mutation of DNMT3B was found in GBM patient samples. Two major DNMT3B splice variants (DNMT3b- V3 and DNMT3b - V7) were found differentially exist in these tumor samples. Functions of these variants are subject to further elucidation.
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