中国人胃癌骨形态发生蛋白3基因遗传的不稳定和甲基化

Genetic instability and methylation of bone morphogenic protein 3 gene in the gastric cancer in Chinese

目的探讨骨形态发生蛋白3(BMP3)基因遗传不稳定性及异常甲基化与胃癌进展的关系,为揭示BMP3基因作用机制和胃癌发生发展机制提供实验依据。方法采用聚合酶链反应-单链构象多态(PCR-SSCP)技术分析中国人胃癌BMP3基因D4S2922、D4S2964位点微卫星不稳定性(MSI)和杂合性缺失(LOH);使用甲基化特异PCR法检测BMP3基因启动子的甲基化状况。结果在本实验中,50例胃癌标本BMP3基因微卫星位点MSI、LOH的阳性率分别为16.00%和20.00%,并且LOH检出率在胃癌的TNMⅢ+Ⅳ期高于Ⅰ+Ⅱ期(P<0.01),并随淋巴转移的发生而增高(P<0.01)。45例胃癌标本中BMP3基因启动子区域甲基化阳性率为64.44%,其检出率与胃癌分化程度、浆膜浸润、淋巴转移及TNM分期均无关。此外,MSI阴性组的甲基化阳性率为71.05%,显著高于MSI阴性组的28.58%(P<0.05)。结论 BMP3基因遗传不稳定和启动子甲基化存在于胃癌的发生发展中。LOH多发生于胃癌的晚期阶段并赋予胃癌高侵袭、预后差的表型。BMP3基因启动子高甲基化可能是胃癌发生因素之一。

Objective This project is to explore the influence of mierosatellite instability （MSI）, loss of heterozygosity （LOH）, as well as promoter region methylation in bone morphogenetie protein 3 （BMP3） on gastric carcinoma development. Methods LOH and MSI of locus D4S2922 and D4S2964 in 50 primary gastric carcinoma specimens were detected by polymerase chain reaction-single strand conformation polymorphism analysis （PCR-SSCP） and methylation-specific PCR analysis in the study. Results The positive rates of MSI, LOH was 16.00% and 20. 00% in 50 specimens respectively, and the frequency of LOH in lymph node metastasis cases was significantly higher than those without. TNM stage Ⅲ and Ⅳ also exhibited higher LOH frequency compared with stage Ⅰ and Ⅱ. The positive rate of methylation on BMP3 gene promoter was 64.44% in 45 specimens. Moreover, the MSI negative group exhibited higher methylation frequency than that of MSI positive group. Conclusion These data suggested that BMP3 genetic instability and promoter methylation were initiated during the gastric carcinogenesis. LOH was detected mostly in the late stage of the gastric carcinoma progression, which indicated higher eareinoma infiltration and poor prognosis. Promotor region methylation of BMP3 gene might be causative in the gastric carcinoma cases in Chinese.