A STUDY OF REGULATORY MOLECULES INVOLVED IN HEPATOCARCINOGENESIS IN A TRANSGENIC MOUSE MODEL

肝细胞癌是慢性病毒性肝炎的常见并发症。最近，我们报道了Fas配体(FasL)在慢性免疫介导的肝细胞损伤中的重要作用，从而增加了肝癌的发病率(J Exp Med 196：1105,2002)；然而，可能导致肿瘤发生的分子机制还不是很清楚。在目前的研究中，我们询问了在乙型肝炎病毒转基因小鼠模型中表现出不同致癌潜能的肝病调节分子。结果如下：1)CD8~+含量高的脾细胞转移后，疾病动力学延长，肝细胞的凋亡和再生程度明显增加。在14只小鼠中，有12只发生了多发性肝细胞癌，其表现与移植全脾细胞的小鼠相似。相反，接受了cd4^+浓缩细胞的小鼠表现出较低的…水平。肝脏疾病的ELS较多，而肝癌的发生率较低(4/17)。实验还显示，所有合并肝癌的小鼠的平均肿瘤数量和大小都是相似的。在该模型中，B细胞耗竭对疾病动力学没有影响。(癌症研究：3326,2004)2)在超过12个月的疾病进展过程中，352个(1.7%)基因在抗FasL单抗治疗组和PBS治疗组小鼠之间差异表达(P&lt；0.05)，其中190个基因根据基因本体论分类被分配到功能组。在酶基因、细胞通讯基因、细胞成分基因、信号转导基因和核酸结合基因中，分别有43个基因(占基因组的1.6%)、42个基因(占基因组的2.0%)、31个基因(占基因组的1.3%)、28个基因(占基因组的1.4%)和22个基因(占基因组的1.8%)发生了显著变化。在细胞通讯组中，很高比例(4.3%)的细胞死亡控制基因参与了这种表达动态。3)我们发现了几个在癌前病变中差异表达的基因。在这些基因中，我们重点研究了Pim-3，据报道它是原癌基因Pim家族的成员，但它在肝癌发生中的作用仍然不清楚。该基因在人肝癌细胞系中有选择性地表达，而在正常肝组织中未见表达。PIM-3蛋白在人肝细胞癌组织和细胞系中也有表达，而在正常肝细胞中不表达。此外，通过RNA干扰去除Pim-3基因的表达，抑制了人肝癌细胞系HepsB和Huh7的细胞增殖。(国际癌症杂志114：209,2005)综上所述，这些数据提示了可能导致肝癌发生的分子机制，以及未来发展分子靶点的研究。较少

Hepatocellular carcinoma (HCC) is a common complication of chronic viral hepatitis. Recently, we have reported that Fas ligand (FasL) is critically involved in the induction of chronic immune-mediated liver cell injury that increases HCC incidence (J Exp Med 196 : 1105, 2002) ; however, the molecular mechanisms potentially responsible for carcinogenesis are not well defined. In the current study, we asked the regulatory molecules in liver diseases that displayed different procarcinogenic potentials in a hpatitis B virus (HBV) transgenic mouse model. The results are summarized as follows.1)Transfer of CD8^+-enriched splenocytes caused prolonged disease kinetics and a marked increase in the extent of hepatocyte apoptosis and regeneration. In 12 out of 14 mice the transfer resulted in multiple hepatocellular carcinomas (HCCs) comparable to the manifestations seen in the mice transferred with total splenocytes. In contrast, mice that had received CD4^+-enriched cells demonstrated lower lev … More els of liver disease and developed fewer incidences of HCC (4 of 17). The experiment also revealed that all the groups of mice complicated with HCC developed comparable mean numbers and sizes of tumors. B cell depletion had no effect on disease kinetics in this model. (Cancer Res. 64 : 3326, 2004)2)During more than twelve months of disease progression, 352 (1.7 % of all) genes were expressed differentially between the mice treated with anti-FasL Ab and with PBS (P<0.05), 190 genes of which were assigned to functional groups based on Gene Ontology categories. In the gene groups of enzymes, cell communication, cellular components, signal transduction, and nucleic acid binding, the significant changes due to anti-FasL Ab treatment were observed in 43(1.6% of the gene group), 42(2.0%), 31(1.3%), 28(1.4%), and 22(1.8%) genes, respectively. In the cell communication group, high proportion (4.3%) of cell death control genes was involved in this expression dynamics.3)We identified several genes expressed differentially at the pre-malignant lesions. Among these genes, we focused on Pim-3, which is reported as a member of a proto-oncogene Pim family, but its contribution to hepatocarcinogenesis remains elusive. The mRNA expression was selectively detected in human hepatoma cell lines, but not in normal liver tissues. Pim-3 protein was also expressed in human hepatocellular carcinoma tissues and cell lines but not in normal hepatocytes. Moreover, cell proliferation was attenuated in human hepatoma cell lines, HepsB and HuH7, by RNA interference ablation of Pim-3 gene expression. (Int.J.Cancer 114 : 209, 2005)Taken together, these data suggest the molecular mechanisms potentially responsible for hepatocarcinogenesis and the future studies for the development of molecular targets. Less