Hepatitis C Virus Core Protein and Cellular Protein HAX-1 Promote 5-Fluorouracil-Mediated Hepatocyte Growth Inhibition
Hepatitis C Virus Core Protein and Cellular Protein HAX-1 Promote 5-Fluorouracil-Mediated Hepatocyte Growth Inhibition
复制标题
DOI：
10.1128/jvi.00872-09
复制
发表时间：
2009-10-01
影响因子：
5.4
通讯作者：
Ray, Ranjit
中科院分区：
文献类型：
--
作者：
Banerjee, Arup;Saito, Kousuke;Ray, Ranjit
丙型肝炎病毒(丙型肝炎病毒)常引起慢性感染，并可能导致肝细胞癌。我们以前已经证明，丙型肝炎病毒核心蛋白具有多效性功能，包括对一些细胞基因的转录调节，尽管基因调节的机制尚不清楚。在这项研究中，哺乳动物双杂交筛选发现了一个新的结合伴侣，HS1相关蛋白X-1(HAX-1)，用于从人肝cDNA文库中获得丙型肝炎病毒核心蛋白。在表达丙型肝炎病毒核心或全长(FL)基因的HepG2细胞中，通过共聚焦显微镜和免疫共沉淀进一步证实了HAX-1与丙型肝炎病毒核心蛋白的相关性。已知丙型肝炎病毒核心蛋白和肝细胞癌化疗药物5-氟尿嘧啶(5-FU)都可以调节P53。我们在这里研究了核心和HAX-1之间的关联是否与5-FU处理的细胞中的P53调节有任何功能上的相关性。为此，通过细胞增殖、P53表达和半胱氨酸天冬氨酸氨基转移酶激活分析，检测了HAX-1在5-FU处理表达丙型肝炎病毒核心或FL基因的HepG2细胞中的作用。表达丙型肝炎病毒核心或FL基因的细胞对5-FU诱导的生长抑制比对照细胞更敏感，而小干扰RNA抑制HAX-1后细胞存活率增加。此外，在核心蛋白或多蛋白表达的细胞中，5-FU介导的P53表达减少，同时HAX-1抑制，与对照细胞相比，caspase-2和-7活性降低。另一方面，在Hep3B或Huh-7细胞中，在缺乏功能性P53的情况下，丙型肝炎病毒核心蛋白在5-FU介导的caspase-7激活中没有发挥可检测到的作用。这些观察结果强调了丙型肝炎病毒核心和HAX-1之间的联系，HAX-1促进了5-FU介导的P53依赖的caspase-7激活和肝细胞生长抑制。
Hepatitis C virus (HCV) often causes chronic infection and may lead to hepatocellular carcinoma (HCC). We have shown previously that HCV core protein has pleiotropic functions, including transcriptional regulation of a number of cellular genes, although the mechanism for gene regulation remains unclear. In this study, a mammalian two-hybrid screen identified a novel binding partner, HS1-associated protein X-1 (HAX-1), for HCV core protein from a human liver cDNA library. An association between HAX-1 and HCV core protein was further verified by confocal microscopy and coimmunoprecipitation in HepG2 cells expressing HCV core or full-length (FL) gene. Both HCV core protein and a chemotherapeutic agent for HCC, 5-flouorouracil (5-FU), are known to modulate p53. We examined here whether an association between core and HAX-1 has any functional relevance to p53 modulation in 5-FU-treated cells. For this, the role of HAX-1 on 5-FU treatment was examined in HepG2 cells expressing HCV core or FL gene using cell proliferation, p53 expression, and caspase activation analysis. Cells expressing HCV-core or FL gene were more susceptible to 5-FU-induced growth inhibition than control cells, whereas cell survival was enhanced after suppression of HAX-1 by small interfering RNA. Further, 5-FU-mediated p53 expression was reduced with concurrent HAX-1 suppression in core-or polyprotein-expressing cells compared to control HepG2 cells, and caspase-2 and -7 activities were diminished. On the other hand, HCV core protein did not play a detectable role in 5-FU-mediated caspase-7 activation in the absence of functional p53 in Hep3B or Huh-7 cells. These observations underscore an association between HCV core and HAX-1, which promotes 5-FU mediated p53-dependent caspase-7 activation and hepatocyte growth inhibition.