肾癌微卫星不稳定性及其机制的研究

目的 探讨微卫星不稳定性（microsatelite instablility,MSI)在肾细胞癌中的表现及与基因突变的关系。方法 用PCR方法分析34例肾细胞癌MSI表现；应用RT－PCR方法检测5种人类错配修复（mismatch repair,MMR)基因在肾细胞癌和肾癌细胞系mRNA转录水平的表达；用PCR－SSCP技术对15例肾细胞癌标本进行MMR基因hMLH1的19个外显子进行筛选，观察基因突变的情况；用PCR方法检查肾癌组织中TGF－βⅡ型受体（TGF－βRⅡ）基因和BAX基因移码突变的情况。结果 34例肾细胞癌中有15例（44．1％）表现为MSI，并多见于晚期肿瘤；15例表达MSI阳性肾癌标本中，3例hMLH1基因mRNA表达缺失，3例表达明显降低，但在正常对照及PCC949细胞系都表达5种MMR基因；PCR－SSCP筛检结果，15例MSI（＋）细胞中3例显示异常电泳带型；40％（6／15）及27％（4／15）分别见TGF－βRⅡ基因及BAX基因移码突变，但不表现在MSI（－）肾肿瘤及正常细胞中。结论 肾细胞癌MSI与MMR基因表达有关，较高的突变率在肿瘤发生中的作用与MSI有关。

Microsatellite instability in renal cell carcinoma and its machanisms

OBJECTIVE: To study the expression of microsatellite instability (MSI) in renal cell carcinoma (RCC) and its relationship with gene mutation. METHODS: Tumor samples from 34 patients with RCC were analyzed for MSI by PCR. RT-PCR was used to evaluate the expression of mRNA of 5 human mismatch repair (MMR) genes in RCC and RCC cell lines. Mutation of hMLH1 gene coding regions was detected by PCR-SSCP. PCR was used to check the mutations of TGF-beta R II gene and BAX gene in 15 MSI-positive samples of RCC. RESULTS: Microsatellite changes were detected in 15 of 34 patients with RCC (44.1%). It might be associated with the progression of this disease. There were 3 of 15 MSI-positive RCC cases without expression of MMR gene hMLH1, and in 3 of 15 cases its expression was decreased. All 5 MMR genes were expressed in normal and RCC 949 cell line. There were three mutations in 15 MSI-positive cases. Frame shift mutation of TGF beta R II gene and BAX gene was found in 6 and 4 of the 15 cases with MSI, respectively, but it was not found in MSI-negative RCC and normal tissue. CONCLUSION: MSI and expression of MMR genes are associated events in RCC. The effect of gene mutation on tumorgenerasis may be related to MSI.