肝细胞癌P53基因突变和蛋白表达的研究

MUTATION OF P53 GENE AND EXPRESSION OF P53 PROTEIN IN HUMAN HEPATOCELLULAR CARCINOMA

为了阐明Ｐ５３肿瘤抑制基因突变在人肝细胞癌发生和发展中的作用，应用聚合酶链反应——单链构象多态性银染技术和ＤＮＡ直接测序法研究了肝细胞Ｐ５３基因的分子结构改变，结果表明：３１％（１３／４２例）的病例显示有Ｐ５３基因突变，低分化癌的突变率显著高于高／中分化癌的突变率（ｘ２检验，Ｐ＜０．０１），突变主要集中于外显子７和外显子８。免疫组织化学染色表明：４２例肝细胞癌中２２例有Ｐ５３蛋白的核内堆积（５１％），低分化癌、ＨＢｓＡｇ阳性病例和伴有肝硬化患者的Ｐ５３蛋白表达率显著高于高／中分化癌、ＨＢｓＡｇ阴性病例和不伴有肝硬化患者的Ｐ５３蛋白表达率（ｘ２检验，Ｐ＜０．０５）。此外，Ｐ５３基因突变和蛋白表达之间存在相关关系（ｘ２检验，Ｐ＜０．０１）。这些资料提示：导致Ｐ５３蛋白异常堆积的Ｐ５３基因突变是肝细胞癌的一种常见的分子结构改变，可能在肝细胞癌的发生和发展中起着重要的作用。

The molecular structural changes of P53 was analyzed by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and silver staining techniques,direct DNA sequencing in human hepatocellular carcinoma.P53 gene mutations were detected in 31%(13 out of 42) of cases.The mutation rate of P53 gene was obviously higher in poorly differentiated carcinoma than highly/moderately differentiated carcinoma(P<0.01).P53 gene mutation was frequent and clustered in exon 7 and 8.Nuclear accumulation of the P53 protein was observed in 22 out of 42 cases of hepatocellular carcinoma(51%) with immunohistochemical method.P53 protein expressions were obviously stronger in poorly differentialted carcinoma,HBsAg-positive cases,the patients who had concomitant liver cirrhosis than in highly/moderately differentiated carcinoma,HBsAg-negative cases,the patients who had not concomitant liver cirrhosis(P<0.05).In addition,there was a correlation between mutation and protein expression level.These data suggest that mutation of P53 gene,which result in abnormal protein accumulation,was a frequent molecular structural change and may have importance in tumor generation and progression in human hepatocellular carcinoma.