Zemel R, Kazatsker A, Greif F, Ben-Ari Z, Greif H, Almog O, Tur-Kaspa R
Molecular Hepatology Research Laboratory, Felsenstein Medical Research Center, Sackler School of Medicine, Tel Aviv University, Israel.
Dig Dis Sci. 2000 Nov;45(11):2199-202. doi: 10.1023/a:1026475421668.
The mechanism of hepatitis C virus (HCV) -induced hepatotocellular carcinoma (HCC) is still unknown, but in vitro studies clearly suggest that HCV proteins exert a direct effect on liver carcinogenesis. HCV NS3 serine protease is known to play a key role in the life cycle of the virus and may interact with the host cellular regulatory proteins. The aim of the present study was to conduct a genetic analysis of the HCV NS3 gene coding for the serine protease isolated from serum, tumor, and nontumor tissue of HCC patients. RNA was extracted and HCV cDNA was amplified by nested reverse transcriptase-polymerase chain reaction (RT-PCR). Sequence comparison yielded unique changes at the vicinity of the catalytic sites of the NS3 clones isolated only from HCC tissue. These changes included the insertion of a "large" and charged amino acid, substitution of a polar with a hydrophobic amino acid, and substitution of a charged with a polar amino acid. Those changes affect the electrostatic charge around the active site, and thus the activity and substrate specificity of the serine protease. This is the first study to define significant amino acid changes at the catalytic domain of the NS3 serine protease gene isolated from HCC tissue.
丙型肝炎病毒（HCV）诱发肝细胞癌（HCC）的机制尚不清楚，但体外研究明确表明，HCV蛋白对肝脏致癌作用有直接影响。已知HCV NS3丝氨酸蛋白酶在病毒生命周期中起关键作用，并且可能与宿主细胞调节蛋白相互作用。本研究的目的是对从HCC患者的血清、肿瘤及非肿瘤组织中分离出的编码丝氨酸蛋白酶的HCV NS3基因进行遗传分析。提取RNA，并通过巢式逆转录聚合酶链反应（RT-PCR）扩增HCV cDNA。序列比较显示，仅从HCC组织分离出的NS3克隆的催化位点附近存在独特变化。这些变化包括插入一个“大的”带电荷氨基酸、一个极性氨基酸被一个疏水氨基酸取代以及一个带电荷氨基酸被一个极性氨基酸取代。这些变化影响活性位点周围的静电荷，进而影响丝氨酸蛋白酶的活性和底物特异性。这是首次界定从HCC组织分离出的NS3丝氨酸蛋白酶基因催化结构域显著氨基酸变化的研究。
