HBV integrants of hepatocellular carcinoma cell lines contain an active enhancer
HBV integrants of hepatocellular carcinoma cell lines contain an active enhancer
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DOI：
10.1038/sj.onc.1204879
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发表时间：
2001-10-18
期刊：
影响因子：
8
通讯作者：
Shaul, Y
中科院分区：
文献类型：
--
作者：
Shamay, M;Agami, R;Shaul, Y
乙型肝炎病毒（HBV）感染是全球范围内发生肝细胞癌（HCC）的主要危险因素。整合的 HBV DNA 片段（通常是高度重排的）经常在 HCC 中检测到。在土拨鼠中，病毒增强子在肝癌发生中起着核心作用，但在人类中，乙型肝炎病毒致癌的机制尚未确定。在这项研究中，我们研究了两种人类 HCC 细胞系 Hep3B 和 PLC/PRF/5 中病毒增强子的状态，每种细胞系均含有一个或多个整合的 HBV DNA 片段。活性增强子是根据基因组体内 DMS 足迹确定的蛋白质占用率来定义的。在 PLC/PRF/5 细胞中，HBV DNA 整合到染色体 11q13 的细胞基因中，据报道该基因座在许多肿瘤中都会扩增。我们在此表明，在两种细胞系中，整合的 HBV DNA 片段都含有活性增强子-I。尤其是先前定义的两个基本增强子元件E和EP的占据尤为突出。虽然在两种细胞系中，相同的蛋白质与 EP 元件结合，但 E 元件以细胞系特异性方式被占据。在 PLC/PRF/5 中，但在 Hep3B 中，未检测到未定义蛋白质的显着结合。我们的数据表明该蛋白很可能是胎蛋白转录因子（FTF）。增强子序列在不同细胞系中是保守且有功能的这一发现表明，其长期维持存在选择压力。因此，我们提出 HBV 增强子-I 可能在肝细胞癌发生中发挥作用。
Hepatitis B virus (HBV) infection is a major risk factor worldwide for the development of hepatocellular carcinoma (HCC). Integrated HBV DNA fragments, often highly rearranged, are frequently detected in HCC. In woodchuck, the viral enhancer plays a central role in hepatocarcinogenesis, but in humans the mechanism of HBV oncogenesis has not been established. In this study we investigated the status of the viral enhancer in two human HCC cell lines, Hep3B and PLC/PRF/5 each containing one or more integrated HBV DNA fragments. Active enhancer was defined by virtue of its protein occupancy as determined by genomic in vivo DMS footprinting. In PLC/ PRF/5 cells, the HBV DNA was integrated in a cellular gene at chromosome 11q13, at a locus reported to be amplified in many tumors. We show here that in both cell lines, the integrated HBV DNA fragments contain an active enhancer-I. In particular, the occupation of the two previously defined basic enhancer elements, E and EP, was prominent. While in both cell lines the same protein binds to the EP elements, the E element, however, is occupied in a cell-line specific manner. In PLC/PRF/5 but not Hep3B, the prominent binding of an undefined protein was detected. Our data suggest that this protein is likely to be the fetoprotein transcription factor (FTF). The finding that enhancer sequences are conserved and functional in different cell lines suggests a selection pressure for their long-term maintenance. We therefore propose that the HBV enhancer-I might play a role in hepatocellular carcinogenesis.