摘要
目的:观察大肠癌组织p14ARF基因遗传和表观遗传变化及p53基因突变状况,探讨两者改变的关系及p14ARF-p53通路功能破坏在大肠癌发生中的作用。方法:应用PCR、直接测序、甲基化特异PCR和RT-PCR分别检测56例原发性大肠癌及相应癌旁正常组织p14ARF基因纯合性缺失、突变、5′CpG岛甲基化、mRNA表达及p53基因突变状况。结果:①大肠癌组织p14ARF总变异率为27%(15/56),其中1例纯合性缺失,14例5′CpG岛甲基化,未见突变发生。②15例p14ARF基因变异的大肠癌组织其相应mRNA表达阴性(13例)或低水平表达(2例),41例未发生基因变异的大肠癌组织和所有癌旁正常组织p14ARFmRNA均显示明显表达。③大肠癌组织p53突变率为48%(27/56)。④56例大肠癌组织中,12例仅发生p14ARF变异,24例仅显示p53突变,3例同时有p14ARF5′CpG岛甲基化和p53突变,17例p14ARF和p53均无变异,p14ARF-p53通路总变异率为70%(39/56),p14ARF5′CpG岛高甲基化与野生型p53状态有关(P<0·05)。⑤低分化腺癌组p14ARF变异率(44%,7/16)明显高于高中分化腺癌组(20%,8/40)(P<0·05),但两组间p53突变率无显著差异(P>0·05)。结论:①大肠癌p14ARF基因5′CpG岛高甲基化是其表达失活的主要机制;②大肠癌p14ARF基因高甲基化与p53基因突变可能是相互独立的事件,两者的失活可能各自出现于不同的大肠癌亚组中;③p14ARF高甲基化或p53突变引起的p14ARF-p53通路功能破坏在大肠癌的发生中具有重要作用。
AIM： To investigate the genetic and epigenetic alterations of p14^ARF gene and mutation status of p53 genc in human primary eolorectal carcinomas and to analyze the relationship between the two gene changes and the role of abrogation of the p14^ARF- p53 pathway in colorectal carcinogenesis. METHODS; The homozygous deletions, mutations, methylatlon of 5＇CpG islands, mRNA expression of p14^ARF gene and mutations of p53 gene were assessed by PCR, direct sequencing, metbylation- specific PCR, and RT-PCR in the tumorous and matched adjacent normal colorectal tissues from 56 patients with colorectal careinoma. RESULTS： ① p14^ARF alterations were detected in 27% （15/56） of colorectal carcinoma tissues studied, of which 1 case showed homozygous deletion, 14 cases showed 5＇CpG island methylation, and no mutation was found in any tumor. ②15 colorectal carcinomas with p14^ARF alterations indicated lack of （ 13 cases） or at low level of expression （2 cases） of p14^ARF mRNA, while expression of the p14^ARF transcript was detected in the remaining 41 colorectal carcinomas and any matebed adjacent normal eolorectal tissues. ③ The mutations of p53 gene were detected in48% （27/56） of colorectal carcinomas investigated. ④ Of these 56 cases, 12 had p14^ARF alterations alone, 24 had p53 mutations alone, 3 had both p53 mutations and p14^ARF metbylation, and 17 had neither. 70% （39/56） of the samples had either or both abnormalities of the two genes, and p14^ARF hypennetbylation was related to wildtype p53 （ P 〈 0.05）. ⑤p14^ARF alterations occurred more frequently in poorly - differentiated adenocarcinomas than that in well and moderately - differentiated adenocareinomas （ P 〈 0.05）, but there was no significant difference in the rate of p53 mutations between them （P 〈0.05）. CONCLUSIONS： p14^ARF gene is mainly inactivated by metbylation of the 5＇ CpG islands in eolorectal cancer. p14^ARF hypennethylation and p53 mutation may be mutually exclusive events in this kind of tumor. The inactivation of these two genes appeared to occur in different tumor subgroupe independently. Disruption of p14^ARF - p53 regulatory pathway by p14^ARF hypermethylation or p53 mutation plays an important role in colorectal carcinogenesis.
出处
《中国病理生理杂志》
CAS
CSCD
北大核心
2006年第6期1191-1195,共5页
Chinese Journal of Pathophysiology
