摘要
目的探讨胃癌组织中与细胞增殖、凋亡和转录有关的基因移码突变与微卫星不稳定性(MSI)的关系。方法采用酚-氯仿-异戊醇法从胃癌及切缘正常石蜡组织中提取DNA。组织切片中肿瘤成分不足50%时采用显微切割方法。以聚合酶链反应-单链构象多态性(PCR-SSCP)、直接DNA测序法检测MSI及转化生长因子βⅡ受体(TGFβRⅡ)、胰岛素生长因子Ⅱ受体(IGFⅡR)、凋亡诱导蛋白BAX和转录因子E2F4基因的移码突变。按照MSI的发生频率将胃癌患者分为3组:出现≥2个位点的MSI为高MSI,出现1个位点的MSI为低MSI,无MSI发生为微卫星稳定。结果61例胃癌患者中,12例(19.7%)为高MSI,11例(18.0%)为低MSI,38例(62.3%)为微卫星稳定。TGFβRⅡ、IGFⅡR、BAX和E2F4移码突变检出率分别为12例(19.7%)、3例(4.9%)、4例(6.6%)和10例(16.4%)。12例高MSI胃癌中,有10例TGFβRⅡ基因突变,3例IGFⅡR基因突变,4例BAX基因突变,10例E2F4基因突变;其移码突变率与高MSI发生密切相关。微卫星稳定组的肿瘤中未发现这些基因的突变。结论TGFβRⅡ、IGFⅡR、BAX和E2F4基因编码区重复序列是MSI发生的靶点,这些基因的移码突变在MSI胃癌的发生和发展中起了重要作用。
Objective To determine the microsatellite instability in gastric carcinomas, examine the frameshift mutations of transforming growth factor-β type Ⅱ receptor （TGFβR Ⅱ ） , insulin growth factor Ⅱ receptor （IGFⅡ R）, bcl-2 associated X protein （BAX） and E2F4, and investigate whether or how alterations of the TGFβR Ⅱ , IGF Ⅱ R, BAX and E2F4 gene are associated with MSI in gastric cancer. Methods Formalin-fixed, paraffln-embedded gastrectomy specimens and matching normal tissues of 65 cases of gastric carcinomas were retrieved from shanghai Ruijin Hospital and Shanghai East Hospital. DNA was extracted from tissue sections using phenol chloral isopantyalcohol. Sections with no more than 50% of tumor cell areas were isolated by microdissection. DNA was amplified by PCR-based single strand conformation polymorphism （SSCP） for microsatellite analysis and was sequenced directly. Frameshift mutations in the coding regions, repetitive mononucleotide tracts of （A）,0 for TGFβR Ⅱ, （G）8 for IGF Ⅱ R, （G）8 for BAX, and trinucleotide repeats of （AGC）13 for transcriptor E2F4 were detected using PCR. Tumors were classified as being microsatellite stable （MSS） or having a low frequency of MSI （ MSI-L, one of markers different in the tumor） or a high frequency of MSI （MSI-H, two or more of markers different）. Results Eleven cases （ 18.0% ） showed MSI-L, 12 （ 19. 7% ） showed MSI-H and 38（62. 3% ） cases showed MSS. The mutation rates of TGFβRⅡ , IGFⅡ R, BAX and E2F4 gene were 19.7%, 4.9%, 6.6% and 16.4% respectively. Among the 12 MSI-H gastric cancers, there were 10 TGFβR Ⅱ mutations, 3 IGF Ⅱ R mutations, 4 BAX mutations and 10 E2F4 gene mutations. The alterations in the repeats of the related genes presented polymorphisms. Associations of MSI-H status and mutations of the 4 genes were highly significant （P 〈0. 01, respectively）. No repeat tracts mutations in TGFβR Ⅱ , IGF Ⅱ R, BAX and E2F4 gene were found in MSS tumors. Conclusions The repeat coding regions within TGFβR Ⅱ , IGF Ⅱ R, BAX and E2F4 gene are the targets of microsatellite instability. Frameshift mutations of the 4 genes play an important role in the development and progression of gastric cancers with microsateUite instability.
出处
《中华外科杂志》
CAS
CSCD
北大核心
2006年第5期344-348,共5页
Chinese Journal of Surgery
基金
上海市医学发展基金资助项目(99ZDI2001)
