人脑胶质瘤抑癌基因p16的研究

Multiple suppressor gene p16 of human brain gliomas

目的 研究抑癌基因p16与原发胶质瘤发生、发展的内在关系。 方法 使用PCR 温度梯度凝胶电泳 (TGGE)的方法 ,对 4 8例脑胶质瘤的第 2外显子进行测定 ,研究p16的缺失和突变 ;同时选用甲基化敏感限制性内切酶与基因组DNA反应 ,然后进行PCR扩增了解p16的甲基化改变。结果 4 8例胶质瘤标本中 ,14例发生p16基因的纯合缺失 ,其中Ⅲ级为 33% (5 /15 ) ;Ⅳ级为 5 0 %(9/18)。对 34例p16扩增阳性标本进行TGGE检测 ,2例有点突变。 4 8例标本中检测到第 2外显子甲基化的有 6例 ,2例为Ⅱ级胶质瘤 ,4例为Ⅲ级胶质瘤 ,甲基化率为 12 % (6 /48)。 结论 p16的改变可能与胶质瘤的发生有一定关系。其中以第 2外显子的纯合缺失为主 ,第 1外显子的甲基化为辅 ,而点突变很少发生。p16缺失主要发生在高级别的胶质瘤中 ,可能为肿瘤发生的较晚期事件。

Objective To study the relationship among p16, genesis, and development of brain gliomas. Methods We detected the deletion and point mutation of p16 exon 2 by PCR TGGE. Methylation sensitivity ristriction enzyme polymerase chain reaction was used to detect whether methylation is correlated with happening of glioma. Results p16 homozygous deletion was detected in 14 of 48 gliomas. No deletions were found in low grade gliomas. Of the 48 gliomas, 5 anaplastic gliomas (WHO grade Ⅲ ) and 9 glioblastomas (WHO grade Ⅳ) showed homozygous deletion of exon 2 with a deletion rate of 33 33%(5/15)and 50 00%(9/18)respectively. The mutations of 34 gliomas with p16 positive amplification were detected point mutations in two gliomas, in which one was anaplatic glioma and the other was glioblastoma. Six of the 48 gliomas(12 5%) showed exon1 methylations. Conclusions p16 may play an important role in genesis of brain glioma. The main alteration of p16 in brain gliomas was homozygous deletion of exon 2, the methylation of p16 exon 1 was subcardinal, however, point mutation was rare.The deletion of p16 was found especially in high grade gliomas, so we could propose that it may be the late event of tumor occurrence.