HCV genetic variation and hepatocellular carcinoma

描述(申请人提供)：慢性丙型肝炎病毒(丙型肝炎病毒)感染可导致肝炎和肝细胞癌。丙型肝炎病毒致癌的机制可能包括病毒蛋白的直接致癌刺激和炎症的间接致癌作用。可能诱发直接致癌刺激的病毒基因包括核心、NS3和NS5A，炎症可能受NS3和NS5A的调节。丙型肝炎病毒的基因变异可以明显影响其致癌潜力，但关于丙型肝炎病毒的高度多样性如何影响肿瘤发生尚无共识，因为病毒遗传分析仅限于对基因组的小区域进行详细检查，或在不敏感的基因水平上表征丙型肝炎病毒的多样性。此外，将致癌潜力归因于丙型肝炎病毒蛋白的生化分析产生了相互矛盾的结果，可能是因为很少有人研究丙型肝炎病毒的遗传多样性。因此，我们将综合分析丙型肝炎病毒的基因变异对致癌潜力的影响，采用协调的遗传和生化方法。假设：丙型肝炎病毒基因变异通过调节促进肿瘤生长和/或中度炎症的病毒蛋白的功能而促进肝细胞癌的发生。目的1.探讨丙型肝炎病毒序列变异与肝细胞癌发生发展的关系。我们将对20例发生肝细胞癌的患者和20例无肝细胞癌的随机人群对照的完整的丙型肝炎病毒蛋白编码区进行测序，并对是否存在与肝细胞癌相关的序列模式进行评估。目的2.确定基因变异如何影响丙型肝炎病毒蛋白的潜在促肿瘤活性。我们将在Aim 1中表达来自肝癌和对照对象的变异的core、NS3/4A和NS5A基因，并检测他们转化细胞和改变细胞周期调控基因转录的能力。我们还将评估在目标1中观察到与肝细胞癌有遗传相关性的其他丙型肝炎病毒基因。目的3.确定基因变异如何影响丙型肝炎病毒蛋白缓解炎症的能力。我们将在Aim 1中表达肝癌和对照对象的NS3/4A和NS5A变异基因，并测量它们的抗炎反应活性。我们还将评估在AIM 1中观察到与肝癌有新的遗传相关性的其他丙型肝炎病毒基因。这些数据将阐明丙型肝炎病毒促进癌症的机制(S)，从而可能确定延缓或阻止肝癌发展的方法。通过发现与肝细胞癌相关的病毒模体，它们还可能导致更大的能力来识别肝癌发展的最高风险患者。

DESCRIPTION (provided by applicant): Chronic Hepatitis C virus (HCV) infection causes hepatitis and hepatocellular carcinoma (HCC). The mechanisms of HCV-induced carcinogenesis are likely to include direct oncogenic stimuli by viral proteins and indirect tumorigenic effects from inflammation. Viral genes that may induce direct oncogenic stimuli include core, NS3, and NS5A, and inflammation could be modulated by NS3 and NS5A. HCV's genetic variation could clearly affect its oncogenic potential, but there is no consensus on how HCV's high diversity may affect oncogenesis because viral genetic analyses have been limited to detailed inspection of small regions of the genome or to characterizing HCV's diversity at the insensitive level of the genotype. Furthermore, biochemical analyses attributing oncogenic potential to HCV proteins have yielded conflicting results, possibly because few have addressed HCV's genetic diversity. Therefore, we will perform a comprehensive analysis of the effect of HCV's genetic variation on carcinogenic potential employing coordinated genetic and biochemical approaches. Hypothesis: HCV genetic variation contributes to development of HCC by modulating function of viral proteins that promote tumor growth and/or moderate inflammation. Aim 1. Correlate HCV sequence variation with development of HCC. We will sequence the complete HCV protein coding region from 20 patients who developed HCC and from 20 random population controls without HCC and the presence of sequence patterns that correlate with HCC will be evaluated. Aim 2. Determine how genetic variation affects putative tumor promoting activities of HCV proteins. We will express variant core, NS3/4A, and NS5A genes from HCC and control subjects in Aim 1 and measure their ability to transform cells and to alter transcription of cell-cycle regulatory genes. We will also assess other HCV genes for which genetic correlations with HCC are observed in Aim 1. Aim 3. Determine how genetic variation affects the ability of HCV proteins to moderate inflammation. We will express variant NS3/4A and NS5A genes from HCC and control subjects in Aim 1 and measure their activities proposed to counteract inflammatory responses. We will also assess other HCV genes for which novel genetic correlations with HCC are observed in Aim 1. These data will clarify the mechanism(s) by which HCV promotes cancer, and hence may identify approaches to delay or halt development of HCC. They may also lead to greater ability to identify patients at highest risk for development of HCC through discovery of viral motifs associated with HCC.