DFF45在肝细胞肝癌中的低表达及其临床意义

Down-regulation of DFF45 in hepatocellular carcinoma and its clinical significance

背景与目的:研究表明DNA裂解因子45(the DNA fragmentation factor 45,DFF45)在肿瘤细胞中表达异常与肿瘤细胞凋亡、分化、恶性表型密切相关。本研究探讨DFF45在肝细胞肝癌(hepatocellularcarcinoma,HCC)组织、癌旁肝组织、正常肝组织、3种不同的肝癌细胞株、永生化的肝细胞株LO2中的表达,并分析其与肝癌患者临床参数的相关性。方法:采用免疫组化、Western blot及RT-PCR检测35例HCC组织及相应癌旁组织、10例正常肝组织中DFF45蛋白及mRNA表达;Western blot、RT-PCR检测肝癌细胞株QGY-7701、SMMC-7721、HepG2及永生化的肝细胞株LO2中DFF45蛋白及mRNA表达。结果:免疫组化显示DFF45在HCC组织、癌旁组织、正常肝组织阳性率分别为48.6%(17/35)、77.1%(27/35)和90%(9/10),HCC组织中DFF45蛋白表达明显低于癌旁及正常组织(P<0.05)。DFF45蛋白的表达与肿瘤大小、病理分级相关。Western blot检测进一步验证了该免疫组化结果。RT-PCR结果显示,DFF45 mRNA在HCC组织中表达(0.453±0.111)同样低于癌旁组织(0.518±0.094)及正常肝组织(0.535±0.112),差异有统计学意义(P<0.05)。DFF45蛋白及mRNA在3种肝癌细胞株中表达均低于永生化的细胞株。结论:DFF45在HCC组织及肝癌细胞系中呈低表达,可能参与了肝癌的发生发展,并有可能成为肝癌治疗的新靶点。

Background and purpose：It was reported that abnormal expression of the DNA fragmentation factor 45（DFF45） is often associated with apoptosis,differentiation and malignancy of tumor.This study aimed to observe the expression level of DFF45 in hepatocellular carcinoma（HCC） tissues,adjacent-tumor tissues,normal liver tissue,3 kinds of HCC cell lines and human immortal liver cell line LO2 and then go further to explore the clinical significance of the expression levels of DFF45.Methods：Immunochemistry,Western blot and RT-PCR were performed on 35 HCC tissues,the corresponding adjacent-tumor tissues,10 normal liver tissues,3 kinds of HCC cell lines QGY-7701,SMMC-7721,HepG2 and human immortal liver cell line LO2 in order to analyze the protein and mRNA levels of DFF45.Results：Positive signals of DFF45 appeared at a lower level in immunochemistry of HCC（48.6%,17/35） compared to those in adjacent-tumor tissues（77.1%,27/35） and normal liver tissues（90%,9/10; P0.05）.Corresponding results were obtained by Western blot and RT-PCR.DFF45 protein levels in HCC（0.462±0.131） were lower compared to those in adjacent-tumor tissues（0.543±0.138） and normal liver tissues（0.593±0.113;PO.05）. DFF45 mRNA levels were significantly decreased in HCC（0.453±0.111）,while higher levels were expressed in adjacent-tumor tissues（0.518±0.094） and normal liver tissues（0.535±0.112;P0.05）.Expression of DFF45 protein was significantly correlated with the pathological grade and the tumor size（P=0.015 and P=0.035）.Protein and mRNA levels of DFF45 were also down regulated in 3 different HCC cell lines compared to those in human immortal liver cell line LO2.Conclusion：Our data demonstrate that expression of DFF45 in HCC is significantly decreased,which may be linked to human HCC carcinogenesis so that DFF45 may be a special treatment target for HCC.