原发性肝细胞癌RIT1基因的突变和扩增

Mutation and amplification of RIT1 gene in hepatocellular carcinoma

目的 探讨 RIT1基因突变和扩增在肝细胞癌 (hepatocellular carcinoma,HCC)的发生情况及其与发病的关系。 方法 采用 PCR直接测序法检测 5 0例原发性 HCC患者的肝癌组织和非癌肝组织RIT1基因在所包含的 6个外显子的全序列寻找突变位点 ;并用荧光定量 PCR法检测 RIT1基因的扩增情况。 结果 在 5 0例肝癌组织中 1例出现第 5外显子编码区 2 4 1位核苷酸 G/ C变异 ,其对应密码子改变为GAG81CAG,编码氨基酸改变为 Glu81Gln,该氨基酸变异位于 GTP结合的保守功能域内 ,该病例的非癌肝组织以及其余 4 9例的肝癌组织和非癌肝组织均未发生此种改变 ;在 5 0例肝癌组织和非癌肝组织中均出现 5′- UTR(起始密码子前 2 1位核苷酸 ) G/ C变异 ;在获得有效扩增数据的 4 3例肝细胞癌患者中 ,11例有 2～2 97倍的 RIT1基因扩增 ,扩增率为 2 5 .6 %。 结论 基因扩增是 RIT1基因在肝细胞癌的激活方式之一 ,可能与肝细胞癌的发病有关 ,而点突变方式可能意义不大。

ObjectiveTo explore the mutation and amplification of RIT1 gene and their correlation with carcinogenesis of hepatocellular carcinoma (HCC). MethodsThe polymerase chain reactioin-direct sequencing method was used for detecting the mutations in the sequence of all 6 exons in the RIT1 gene of 50 HCC tissues and paratumor tissues. And the amplification ofRIT1 gene was examined by fluorescence quantitative polymerase chain reaction method.ResultsA nucleotide 241 G→C substitution in exon 5 of RIT1 gene was detected in one patient's HCC tissue, but not in paratumor tissue;this 241 G→C substitution leads to Glu81Gln amino acid alteration in the conservative domain binding GTP. A nucleotide G→C substitution in 5′-UTR (-21 bp from initial codon) was detected in all of the 50 HCC tissues and paratumor tissues, and 2- to 297-fold amplification ofRIT1 gene was detected in 11 of 43 qualified cases, the amplification frequency being 25.6 %. ConclusionGene amplification is one of the main activating ways of RIT1 gene in HCC, and its amplification might be correlated with HCC carcinogenesis, while point mutation might be not.