Zhong S, Chan J Y, Yeo W, Tam J S, Johnson P J
Department of Clinical Oncology, Sir Y. K. Pao Centre for Cancer, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
J Viral Hepat. 2000 Mar;7(2):115-23. doi: 10.1046/j.1365-2893.2000.00209.x.
The development of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) frequently follows persistent HBV infection and may arise in individuals who are hepatitis B e antigen (HBeAg) negative, indicating the possible presence of precore/core mutants. It is unclear whether precore/core mutants are associated with tumour development or are selected for after chromosomal integration of the wild-type viral DNA. We studied the status and sequence variation of the precore/core region of HBV in 56 patients with HBV-associated HCC and in various corresponding non-tumour tissues by Southern blot analysis, polymerase chain reaction and direct sequencing. Southern blot showed that integrated HBV DNA existed in 43 of 56 HCC tissues. Sequence analysis revealed mutations in 65% of the HCC (26/40) and 45% (14/31) of the corresponding non-tumour tissues. The mutation at nucleotide (nt) 1896, known to prevent HBeAg synthesis, was detected in 40% (16/40) of the tumours and in 35.4% (11/31) of the non-tumour tissues. Other mutations were found at nt 1899 (eight of 40 in HCC; three of 31 in non-tumour tissues), nt 1898 (seven of 40 in HCC; two of 31 in non-tumour tissues), nt 1912 (seven of 40 in HCC; none of 31 in non-tumour tissues) and nt 1886 (three of 40 in HCC; none of 31 in non-tumour tissues). To determine whether this finding merely reflected the prevalence of such mutants in this geographical region, HBV DNA from the sera of patients (also in this region) with acute and chronic hepatitis were sequenced. The nt 1896 mutant was found in 5.6% (one of 18) of patients with acute hepatitis B and in 22.8% (nine of 35) of patients with chronic hepatitis B. However, the nt 1898 mutation was not found in any of these sera. The precore/core mutant was observed with increasing frequency from acute hepatitis to chronic hepatitis, non-tumour and HCC, and this difference in frequency was significant between HCC and acute hepatitis B groups (P < 0.01), suggesting that the precore/core mutant or hepatocytes harbouring this mutant may be under immune selection and that such mutations may facilitate integration and subsequent tumour development.
乙型肝炎病毒（HBV）相关肝细胞癌（HCC）的发生常常继发于持续性HBV感染，且可能出现在乙肝e抗原（HBeAg）阴性的个体中，这表明可能存在前核心/核心区突变体。目前尚不清楚前核心/核心区突变体是与肿瘤发生相关，还是在野生型病毒DNA发生染色体整合后才被选择出来。我们通过Southern印迹分析、聚合酶链反应和直接测序，研究了56例HBV相关HCC患者以及各种相应非肿瘤组织中HBV前核心/核心区的状态和序列变异。Southern印迹显示，56例HCC组织中有43例存在整合的HBV DNA。序列分析显示，65%（26/40）的HCC组织以及45%（14/31）的相应非肿瘤组织存在突变。已知可阻止HBeAg合成的核苷酸（nt）1896位点的突变，在40%（16/40）的肿瘤组织以及35.4%（11/31）的非肿瘤组织中被检测到。在nt 1899（HCC组织中40例有8例；非肿瘤组织中31例有3例）、nt 1898（HCC组织中40例有7例；非肿瘤组织中31例有2例）、nt 1912（HCC组织中40例有7例；非肿瘤组织中31例均无）和nt 1886（HCC组织中40例有3例；非肿瘤组织中31例均无）位点也发现了其他突变。为了确定这一发现是否仅仅反映了该地理区域此类突变体的流行情况，我们对急性和慢性肝炎患者（也在该区域）血清中的HBV DNA进行了测序。nt 1896突变体在5.6%（1/18）的急性乙型肝炎患者和22.8%（9/35）的慢性乙型肝炎患者血清中被发现。然而，在这些血清中均未发现nt 1898突变。从前核心/核心区突变体在急性肝炎、慢性肝炎、非肿瘤组织和HCC组织中的出现频率逐渐升高，且HCC组与急性乙型肝炎组之间这种频率差异具有统计学意义（P < 0.01），这表明前核心/核心区突变体或携带该突变体的肝细胞可能处于免疫选择之下，且此类突变可能促进整合及随后的肿瘤发生。
