The oncogenic potential of hepatitis C virus NS5A sequence variants is associated with PKR regulation
The oncogenic potential of hepatitis C virus NS5A sequence variants is associated with PKR regulation
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DOI：
10.1089/jir.2005.25.152
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发表时间：
2005-03-01
影响因子：
2.3
通讯作者：
Gale, M
中科院分区：
文献类型：
--
作者：
Giménez-Barcons, M;Wang, CF;Gale, M
丙型肝炎病毒（HCV）的NS5A蛋白具有细胞生长调控作用，并与病毒肿瘤发生有关。在这里，我们研究了从hcv感染患者中获得的高度分化的NS5A蛋白在哺乳动物细胞中表达时是否具有致癌潜力。一般来说，NS5A的表达与细胞生长和培养增殖的增加有关。表达这些序列子集的永生化原代肝细胞和永生化成纤维细胞系表现出蛋白质合成率、培养饱和密度和转化细胞表型的显著增加，这是由软琼脂试验中不依赖锚定的细胞生长和集落形成所显示的。致癌转化与蛋白激酶R （PKR）活性的抑制和真核起始因子2 α (elF2 α)磷酸化水平的降低相关，从而引起mRNA翻译的刺激。整个NS5A或先前表征的PKR结合区域内的序列变异程度并不是该细胞表型的预测指标，这表明该区域外的序列有助于PKR调控。我们的数据表明，NS5A的致癌潜力是有条件的，通过病毒序列变异。这些结果为PKR通路作为细胞生长控制的中介提供了进一步的证据，并表明PKR的病毒调节可能有助于慢性HCV感染期间肝细胞生长失调。
The NS5A protein of hepatitis C virus (HCV) confers cell growth regulation and has been implicated in viral oncogenesis. Here, we investigated whether highly divergent NS5A proteins obtained from HCV-infected patients presented an oncogenic potential when expressed in mammalian cells. In general, NS5A expression was associated with increased rates of cell growth and culture proliferation. Immortalized primary hepatocyte and immortalized fibroblast cell lines expressing a subset of these sequences exhibited a significant increase in protein synthetic rate, culture saturation density, and a transformed cellular phenotype, as shown by anchorage-independent cell growth and colony formation in soft agar assays. Oncogenic transformation correlated with inhibition of protein kinase R (PKR) activity and concomitant reduction of eukaryotic initiation factor 2 alpha (elF2 alpha) phosphorylation levels that caused stimulation of mRNA translation. The extent of sequence variation throughout NS5A or within the previously characterized PKR-binding domain was not a predictive indicator of this cellular phenotype, suggesting that sequences outside this region contribute to PKR regulation. Our data indicate that NS5A oncogenic potential is conditional through viral sequence variation. These results provide further evidence to define the PKR pathway as a mediator of cell growth control and suggest that viral regulation of PKR may contribute to hepatocyte growth deregulation during chronic HCV infection.