Inhibition of hepatitis B virus expression and replication by RNA interference in HepG2.2.15

INTRODUCTION Hepatitis B is a severe infectious disease threatening peoples’ health all over the world. There is still no efficient therapy to control HBV persistent replication, which may lead to the development of liver cirrhosis and hepatocellualar ca…     

长片段RNA抑制HepG2.2.15细胞中HBV基因的表达和复制

目的 评估长的反义RNA干扰片段在培养细胞株中对HBV复制的抑制效应.方法将HBV基因组S区的全部核苷酸序列插入至pTARGETTM载体中,并将重组载体转染入HepG2.2.15细胞中.用酶联免疫吸附法检测HBsAg与HBeAg水平,用荧光定量PCR法检测HBVDNA水平.对数据采用多个独立样本Kruskal-Wallis检验与两两比较的Mann-Whitney U检验.结果 经过处理后,HepG2.2.15细胞上清液中HBsAg表达量(A值)在HBS2组(携带长片段反义RNA)为0.621±0.027,在HBS4组(携带正义RNA)为3.399±0.018,对照组为2.232±0.187;HBeAg表达量(A值)在HBS2组、HBS4组和对照组分别为0.749±0.019、1.548±0.025和1.570±0.044; HBV DNA水平(×104拷贝/ml)在HBS2组、HBS4组、对照组分别为1.597±0.082、3.381±0.297和3.610±0.063.与对照组相比,HBS2组HBsAg、HBeAg和HBV DNA表达量均降低,统计量Z值均为-2.309,P值均＜0.05; HBS4组HBsAg表达量增高(Z=-2.309,P＜0.05),而HBeAg和HBV DNA表达量无明显差异,统计量Z值分别为-0.866、-1.155,P值均＞0.05.结论 长片段反义RNA能抑制HBV基因的表达和病毒复制.

Abstract：

Objective To evaluate the inhibitory effects of long antisense RNA on HBV replication in HepG2.2.15 cells. Methods The coding region of HBV S gene was cloned into pTARGET vector in sense and antisense orientations and the recombinant plasmids were transfected into HepG2.2.15 cells which were divided into HBS2 (antisense RNA) group, HBS4 (sense RNA) group and control group. HBsAg and HBeAg in the culture supernant were detected by ELISA. The HBV DNA in the supernant was quantified by real-time PCR. Results After treatment, the levels of HBsAg in HepG2.2.15 cell supernatants of three groups were 0.621 ± 0.027, 3.399 ± 0.018 and 2.232 ± 0.187 respectively; the levels of HBeAg were 0.749 ± 0.019,1.548 ± 0.025 and 1.570 ± 0.044 respectively and the levels of HBV DNA were 1.597 ± 0.082, 3.381 ± 0.297 and 3.610 ± 0.063 respectively. The expressions of HBsAg and HBeAg and the HBV DNA level in HBS2 group were remarkably reduced as compared to the control (Z = -2.309, P ＜ 0.05); whereas the sense plasmid transfection (HBS4) did not affect HBeAg (Z= -0.866) and HBV DNA (Z = -1.155) levels in the culture supernant but slightly increased the HBsAg level (Z = -2.309). Conclusion Antisense RNA might be a useful tool to repress HBV replication.     

青蒿琥酯对乙型肝炎病毒复制及肝癌细胞株HepG2.2.15凋亡的影响

目的 探讨青蒿琥酯在体外对乙型肝炎病毒复制及肝癌细胞株HepG2.2.15凋亡的影响.方法 将不同浓度青蒿琥酯作用于转染乙型肝炎病毒全基因组DNA的肝癌细胞株HepG2.2.15,收集48 h上清,采用酶联免疫吸附实验检测上清中乙型肝炎病毒表面抗原(HBsAg)和e抗原(HBeAg),采用荧光定量PCR法检测HBV-DNA,流式细胞术检测细胞凋亡.结果 青蒿琥酯对HBV复制具有抑制作用,随着浓度增加,对HBsAg和HBeAg的抑制率逐渐上升,细胞内HBV-DNA 复制水平下降;青蒿琥酯可诱导肝癌细胞早期凋亡及导致细胞死亡,随浓度增加,HepG2.2.15细胞早期凋亡率及死亡率均增加.结论 青蒿琥酯对HepG2.2.15细胞HBsAg和HBeAg的分泌及HBV-DNA复制具有抑制作用,并具有诱导HepG2.2.15细胞凋亡的作用.     

RNAi对HepG2．2．15细胞HBx基因表达和细胞迁徙的影响

目的探讨HBx基因在肝细胞癌侵袭转移中的作用。方法利用psiRNA-hHlneo质粒，构建针对HBx基因的shRNA表达载体psiRNA1、psiRNA2、psiRNA3，并转染HepG2．2．15细胞，用逆转录聚合酶链反应检测shRNA对HBx基因mRNA表达，用免疫印迹法（western Blot）检测shRNA对HBx蛋白的表达。应用改良Boyden小室法测定细胞迁移情况。结果成功构建shRNA表达载体，其中shRNA载体psiRNA1对HBx基因的抑制作用最强，对HBxmRNA抑制率达82．46％，对HBx蛋白的抑制率为65．59％；与空载体转染细胞比较，HepG2．2．15细胞在psiRNA1转染后24h、72h迁移率显著下降。结论HBx基因可能促进HCC的侵袭转移。     

HBV preS2反义锁核酸在HepG22.2.15细胞内的抗病毒效果

目的:探讨针对HBV preS2基因mRNA翻译起始区的反义锁核酸(LNA)片段在2.2.15细胞内抗HBV复制和表达的作用.方法:分别合成三段互补于HBV preS2基因mRNA翻译起始区同一靶位的反义锁核酸、全硫代反义寡核苷酸、未修饰寡核苷酸及无关对照序列,以阳离子脂质体作为载药体系,作用于HepG22.2.15细胞,采用时间分辨免疫荧光技术(TRFIA)和荧光定量聚合酶链技术(FQ-PCR)动态检测细胞上清液中HBsAg和HBV DNA的含量,并比较其抑制HBV DNA复制与表达的作用;以四甲基偶氮唑蓝(MTT)法检测LNA对细胞的毒性.结果:加入LNA后第1天,即出现对HBsAg表达和HBV DNA复制的抑制作用,第7天,未修饰反义寡核苷酸组、全硫代修饰反义寡核苷酸组、反义锁核酸组对HBsAg表达的抑制率分别达45.79%、52.92%和67.21%;对HBVDNA复制的抑制率分别达35.15%、40.69%和52.16%.其中LNA抑制病毒活性最强且对细胞代谢无影响.各组与对照组比较均有显著性差异(均P<0.01),且反义LNA组与其他ASODN组比较也有显著性差异(均P<0.05).结论:针对preS2基因的反义锁核酸体外能有效抑制HBV的复制与表达,故preS2基因可作为乙型肝炎基因治疗的有效靶位.     

乙型肝炎病毒核心蛋白在HepG2.2.15细胞中的亚细胞定位及转移

目的观察HepG2．2．15细胞内HBV核心蛋白的亚细胞定位及转移，了解核心蛋白的入核机制。方法2％二甲亚砜或（和）1μmol／LBay414109处理HepG2．2．15细胞4d；荧光共聚焦显微镜观察HBsAg和HBcAg在细胞内的定位；Westernblot检测胞质和胞核中的HBcAg水平；选择性PCR检测胞核内HBV共价闭合环状DNA（cccDNA）水平。结果二甲亚砜处理提高了胞质和胞核内的HBcAg表达及核内的cccDNA水平；Bay414109处理后胞质中HBcAg水平下降但胞核中HBcAg水平上升，cccDNA水平下降；联合应用二甲亚砜和Bay41—4109处理后HBsAg在胞质内呈条索状分布，胞质中HBcAg水平下降，但胞核内HBcAg明显上升，cccDNA水平下降。结论HepG2．2．15细胞中存在HBV核心颗粒入核障碍，游离核心蛋白易于通过核孔，二甲亚砜可促进核心蛋白进入细胞核，并有助于cccDNA的形成。     

Inhibition of hepatitis B virus production associated with high levels of intracellular viral DNA intermediates in iron-depleted HepG2.2.15 cells

BACKGROUNDS/AIMS: The effects of iron-depletion on hepatitis B virus (HBV) replication were examined in HepG2.2.15 cells. METHODS: Proliferating cells were iron-depleted with desferrioxamine (DFO), at 20 or 100 microM for 48 h. Levels of viral mRNAs, cytoplasmic DNA replicative intermediates and virion production were examined. A comparative study was performed with hydroxyurea, a specific inhibitor of ribonucleotide reductase. RESULTS: In desferrioxamine treated cells, virion production is dramatically decreased, while viral replicative intermediates accumulate in the cytoplasm. DFO, like hydroxyurea, blocks cell cycle progression in the G1/S transition or S phase with a corresponding 2-fold increase of viral mRNAs. As expected, hydroxyurea leads to a strong reduction of virion production associated with low levels of intracellular replicative intermediates. CONCLUSIONS: These results strongly suggest that iron depletion affects the HBV life cycle indirectly through the cell cycle arrest and directly through the inhibition of the viral DNA secretion. They also indicate the need to re-evaluate with caution the iron depletion protocols on HBV infected patients since a decrease of viral markers in the serum following iron-depletion may not reflect a decrease of viral replicative forms, but on the contrary, could be associated with active viral DNA synthesis.     

Dynamic analysis of hepatitis B virus DNA and its antigens in 2.2.15 cells

The 2.2.15 cells-derived from HepG2 cells transfected with a plasmid containing hepatitis B virus (HBV) DNA secrete surface antigen (HBsAg) particles, nucleocapsids and virions (Proc Natl Acad Sci U S A 1987; 84: 1005-1009). The latter elicit acute hepatitis in chimpanzees (Proc Natl Acad Sci U S A 1987; 84: 4641-4644). We studied the presence of intracellular and extracellular HBV covalently closed circular (ccc) DNA in this culture system by polymerase chain reaction (PCR), kinetically analysed HBsAg and hepatitis B e antigen (HBeAg) released in the culture media by quantitative enzyme-linked immunosorbent assay and quantitated by real-time PCR but HBV DNA from intracellular and extracellular HBV-DNA. HBV cccDNA was found both intracellularly and extracellularly. A significant correlation was seen between the extracellular HBV DNA levels and virus antigens (r = 0.833; P = 0.01 and r = 0.939; P < 0.01 for HBsAg and HBeAg, respectively), whereas there was no statistical correlation between intracellular HBV DNA levels and virus antigen levels (r = 0.024; P = 0.955 and r = 0.177; P = 0.625 for HBsAg and HBeAg, respectively). These data would be valuable in studies of the HBV life cycle and of potential anti-viral agents.     

Combination of small interfering RNA and lamivudine on inhibition of human B virus replication in HepG2.2.15 cells

AIM: To observe the inhibition of hepatitis B virus (HBV) replication and expression by combination of siRNA and lamivudine in HepG2.2.15 cells. METHODS: Recombinant plasmid psil-HBV was constructed and transfected into HepG2.2.15 cells. The transfected cells were cultured in lamivudine-containing medium (0.05 μmol/L) and harvested at 48, 72 and 96 h. The concentration of HBeAg and HBsAg was determined using ELISA. HBV DNA replication was examined by real- time PCR and the level of HBV mRNA was measured by RT-PCR. RESULTS: In HepG2.2.15 cells treated with combination of siRNA and lamivudine, the secretion of HBeAg and HBsAg into the supernatant was found to be inhibited by 91.80% and 82.40% (2.89 ± 0.48 vs 11.73 ± 0.38, P < 0.05; 4.59 ± 0.57 vs 16.25 ± 0.48, P < 0.05) at 96 h, respectively; the number of HBV DNA copies within culture medium was also significantly decreased at 96 h (1.04 ± 0.26 vs 8.35 ± 0.33, P < 0.05). Moreover, mRNA concentration in HepG2.2.15 cells treated with combination of siRNA and lamivudine was obviously lower compared to those treated either with siRNA or lamivudine (19.44 ± 0.17 vs 33.27 ± 0.21 or 79.9 ± 0.13, P < 0.05). CONCLUSION: Combination of siRNA and lamivudine is more effective in inhibiting HBV replication as compared to the single use of siRNA or lamivudine in HepG2.2.15 cells.     

Evaluation of hepatitis B viral replication and proteomic analysis of HepG2.2.15 cell line after knockdown of HBx

BACKGROUND:Hepatitis B virus (HBV) is one of the major pathogens of human liver disease.Studies have shown that HBV X protein (HBx) plays an important role in promoting viral gene expression and replication.In this study we performed a global proteomic profiling to identify the downstream functional proteins of HBx,thereby detecting the mechanisms of action of HBx on virion replication.METHODS:HBx in the HepG2.2.15 cell line was knocked down by the transfection of small interfering RNA (siRNA).The replicati...     

乙型肝炎病毒X蛋白上调HepG2细胞中SMYD3的表达

目的 探讨HBV是否通过调控组蛋白甲基化酶SMYD3的表达参与肝癌细胞的恶性生物学行为.方法 通过向肝癌细胞HepG2转染HBx筛选出表达HBx蛋白的细胞株HepG2-HBx.用激光共聚焦定位细胞内HBx蛋白和SMYD3蛋白的表达;实时逆转录PCR、Western blot检测转染HBx前后HepG2细胞中SMYD3 mRNA和蛋白质的表达水平;流式细胞仪检测转染HBx前后HepG2细胞增殖、凋亡的变化情况.对数据进行单因素方差分析. 结果 HBx转染后HepG2细胞中SMYD3 mRNA和蛋白质表达水平明显上调(SMYD3 mRNA:0.18±0.05与0.98±0.15,F=37.240,P<0.05;SMYD3蛋白:0.28±0.03与0.58±0.06,F=21.042,P<0.05).转染HBx后HepG2细胞凋亡率下降(7.90%±0.42%与2.23%±0.14%,P<0.01),细胞增殖能力增强(28.46%±4.33%与36.46%±0.17%,P<0.01).结论 乙型肝炎病毒X蛋白能够上调HepG2细胞中SMYD3 mRNA和蛋白质表达水平;HBx可能通过SMYD3-组蛋白甲基化途径抑制HepG2细胞凋亡、促进细胞增殖.     

Increased apoptosis in HepG2.2.15 cells with hepatitis B virus expression by synergistic induction of interferon‐γ and tumour necrosis factor‐α

Background: Interferon‐γ (IFN‐γ) and tumour necrosis factor‐α (TNF‐α) were thought to be important immune mediators in host defence against hepatitis B virus (HBV) infection. Aims: To examine the synergistic effect of IFN‐γ and TNF‐α on HBV‐expressing HepG2.2.15 cells and its potential mechanisms. Methods: Cell viability was quantitatively measured by 3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5‐diphenyl tetrazolium bromide assay. Cell morphology was captured using light microscopy. The typical DNA ladder test was performed using agarose gel electrophoresis. HBsAg and HBeAg titre changes were quantified by the enzyme‐linked immunosorbent assay method. Gene expression was analysed using cDNA macroarrays. Results: Interferon‐γ (1000 U/ml) alone or combined with TNF‐α (5 ng/ml) treatment resulted in apoptosis in HepG2.2.15 cells, but no significant apoptosis in the parent non‐virus expressing HepG2 cells. IFN‐γ‐ and TNF‐α‐mediated apoptosis was reduced by lamivudine treatment in HepG2.2.15 cells. IFN‐γ combined with TNF‐α reduced the titre of hepatitis B surface antigen and hepatitis B e antigen in the HepG2.2.15 cell line. For apoptosis‐related gene changes, IFN regulatory factor 1 (IRF‐1) (12.2‐fold), c‐myc (V00568 4.7‐fold, L00058 2.4‐fold) and caspase 7 (2.3‐fold) genes were upregulated in the combination treatment group. Conclusion: Interferon‐γ and TNF‐α play a role in the cell death of HBV‐expressing HepG2.2.15 cells. Expression of HBV leads to IFN‐γ‐ and TNF‐α‐mediated apoptosis in the cells. Increased IRF‐1, c‐myc and caspase 7 gene expression may be responsible for the synergistic induction of apoptosis by IFN‐γ and TNF‐α.     

Tissue and organ culture studies of hepatitis B virus.

Techniques have been developed for the cultivation of human and nonhuman primate liver cells in tissue and organ culture. Progressive non-cytocidal involvement of the normal cytoplasmic and nuclear components of cultured liver cells has been demonstrated by specific attachment of fluorescent antibody to hepatitis B core and surface antigens after inoculation of the cultures of human origin with known infective sera and with clinical material. Hepatitis B surface antigen may be produced, although infrequently, in inoculated liver organ cultures but serial passage has not been achieved. Serial passage of hepatitis B virus has been reported with fragments of human embryo liver cultivated on the chorioallantoic membrane of the developing chick embryo. Intranuclear virus-like particles have been localized in hepatocytes of cultured explants of liver biopsies obtained from infants with chronic hepatitis B antigenemia. Further studies are urgently required to determine whether cultivation of hepatitis B virus can be firmly established in readily available cell and organ cultures.     

Immunocytochemical and electron microscopic study of hepatitis B virus antigen and complete particle production in hepatitis B virus DNA transfected HepG2 cells

The relationship between the presence of hepatitis B virus antigens, their localization and hepatitis B virus replication was studied in different clones of cultured HepG2 hepatoblastoma cells transfected with cloned hepatitis B virus DNA. Intracellular hepatitis B virus antigens were detected by immunofluorescence. The production of these antigens was evaluated in the culture media by enzyme-linked immunoassay. Hepatitis B virus DNA was detected using dot-blot hybridization. Three types of HBcAg staining were observed in transfected HepG2 cells: (a) cells with nuclear HBcAg, (b) cells with cytoplasmic HBcAg and (c) cells with both nuclear and cytoplasmic HBcAg. Cell types b and c also expressed hepatitis B virus DNA in their culture media. Our results suggest that cytoplasmic HBcAg may be more involved than nuclear HBcAg in hepatitis B virus replication. The site of hepatitis B virus formation in hepatocytes was studied by electron microscopic examination of a specific hepatitis B virus producer clone, thereby allowing detection of intracellular Dane particles more easily than liver biopsy samples from infected patients. Dane particles and HBsAg filaments were found in large, dilated structures probably related to the endoplasmic reticulum. Budding of core particles into cisternae of endoplasmic reticulum-related structures appears to be a possible mechanism for hepatitis B virus formation; our results suggest that the exocytosis of cisternae to extracellular spaces may be a mechanism for release of hepatitis B virus particles.     

乙型肝炎病毒在HepG2细胞中的稳定复制及表达

目的 建立HBVHepG2肝细胞株，使HBV能长期稳定地表达抗原并复制。方法将含完整转录单位的1．2倍体HBVDNA经Sal1位点克隆入真核表达载体pREP10，构建的重组载体pREP—HBV以Lipofemamine2000转染HepG2细胞，250μg／ml。潮霉素筛选抗性细胞克隆。ELISA检测细胞上清液中的HBsAg和HBeAg。电子显微镜下观察细胞上清液HBV颗粒。制备HBV特异性探针，以Southern印迹法检测细胞株内HBV核心颗粒DNA。结果获得含1．2倍体HBVDNA的重组载体，即pREP—HBV，该重组载体转染HepG2细胞后，获得5株潮霉素抗性细胞RHBV1～RHBV5。均能表达HBsAg和HBeAg。Southern印迹结果显示各株细胞均可见明显的杂交拖带，即存在HBVDNA复制中间体。细胞培养上清液浓缩后在电子显微镜下可见成簇的、直径约42nm的HBV颗粒及直径为22～26nm的球形颗粒。结论 成功建立了HBV稳定复制及表达的HepG2细胞株，目前细胞已传代50次，每3天1次。     

乙型肝炎病毒核壳蛋白变异株在HepG2细胞的HLA-Ⅰ表达

目的:研究HBV adr亚型野生株和核壳蛋白变异株在HepG2细胞表面的HLA-Ⅰ/抗原肽复合物的表达.方法:通过定点突变技术将1.2拷贝HBV野生型质粒p3.8Ⅱ构建成核壳蛋白变异株V60和L97.经序列测定和生物学活性检测后,野生株和变异株重组质粒分别亚克隆入EB病毒表达载体EBO-plpp以稳定表达.重组载体EBO-野生株、EBO-V60和EBO-L97分别作内切酶双酶切和序列测定鉴定,再用脂质体介导转染HepG2细胞,ELISA(Abbott)试剂盒定量检测各株培养上清HBV抗原,转染细胞用FITC标记的鼠抗HLA-ABC单抗染色,流式细胞术分析细胞表面HLA-I表达.结果:3株重组载体经内切酶消化,电泳后显示2条区带,分别与1.2拷贝HBV基因组和EBO载体大小相同.测序结果证实EBO-V60和EBO-L97分别在nt2078 C→G和nt2189 A→C,保持原定点突变.EBO-野生株的培养上清HBeAg定量S/CO值明显高于变异株V60和L97,3株HBsAg定量S/N值接近,HBsAg表达相近表明实验的转染效率相当.EBO空载体转染的HepG2细胞HLA-I轻微表达,3株重组载体转染细胞HLA-I的荧光强度不同,野生株增强为18.2,L97明显升高至34.5,而V60降低至3.4.结论:HBV能增强HepG2细胞表面HLA-I/抗原肽复合物的表达,核壳蛋白热点变异V60和L97可使宿主细胞HLA-Ⅰ表达发生变化.