41例人脑胶质瘤组织中p53基因突变的研究

背景与目的:p53抑癌基因在细胞周期的调控、维持细胞基因组的完整性、诱导细胞分化和凋亡中起着重要作用。胶质瘤尤其是星形细胞肿瘤中,经常发生p53基因突变。本研究探讨人脑胶质瘤中p53突变及与胶质瘤发生发展的相关性。方法:应用聚合酶链反应-单链构象多态性分析(polymerase chainreaction-single-strand conformation polymorphism,PCR-SSCP)及DNA测序技术对41例不同类型人脑胶质瘤p53基因突变进行检测。结果:通过PCR-SSCP检测发现在41例人脑胶质瘤组织中有17例(41.5%)呈现p53基因的单链构象多态性改变,均位于5～8外显子,突变例数依次为7(41.2%)、1(5.9%)、4(23.5%)、5(29.4%)。Ⅲ、Ⅳ级胶质瘤中p53基因突变率明显高于Ⅰ、Ⅱ级肿瘤(58.3%vs.17.6%,P<0.01);DNA序列分析显示,17例PCR-SSCP检测阳性的肿瘤p53基因相应外显子均存在基因点突变或缺失,其中错义突变13例,占76.5%;同义突变2例,占11.8%;移码突变2例,占11.8%;碱基突变以G→A或A→G最多,占55.6%。结论:胶质瘤中p53突变多发生于第5、8外显子,基因突变类型以错义突变为主,该基因的突变与胶质瘤的发生及恶性进展过程相关。

Mutations of p53 gene in 41 cases of human brain gliomas

BACKGROUND & OBJECTIVE: p53 gene plays an important role in regulating cell cycle, maintaining completeness of cellular genomes, inducing cell differentiation and apoptosis. p53 gene mutation occurs usually in gliomas, especially astrocytomas. This study was to investigate p53 gene mutation and its correlation to the development of glioma. METHODS: p53 gene mutation in 41 specimens of human gliomas was analyzed by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and DNA sequencing. RESULTS: p53 gene mutations were found in 17 (41.5%) of the 41 specimens of gliomas. The p53 mutations located on exons 5-8: 7 cases (41.2%) on exon 5; 1 (5.9%) on exon 6; 4 (23.5%) on exon 7; 5 (29.4%) on exon 8. The mutation rate of p53 gene was significantly higher in grade III-IV gliomas than in grade I-II gliomas (P<0.01). DNA sequencing indicated that the p53 gene mutations were point mutations and deletions of exons in the 17 positive cases, including 13 cases (76.5%) of missense mutation, 2 cases (11.8%) of samesense mutation, and 2 cases (11.8%) of frame shift mutation. G_A and A-->G were major base mutations (55.6%). CONCLUSIONS: p53 mutations always locate on exons 5 and 8. Missense mutation is major mutant type of p53 gene. p53 mutation plays an important role in the development and malignant transformation of human gliomas.