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Objective: To study the effects of hepatitis B virus (HBV) infection on the expression of Furin, an important proprotein convertase, in liver cells to provide insights towards its potential as a therapeutic target for improved antiviral efficacy., Methods: Furin expression was measured in human liver specimens (infected tissues from patients with chronic HBV hepatitis vs. normal tissues from healthy donors) and in hepatoma cell lines (HBV-infected HepG2.2.15 cells vs. uninfected parental cell lines HepG2) using quantitative real-time RT-PCR (for mRNA), western blotting and immunohistochemistry (for protein)., Results: Compared to the uninfected tissues and cells, the HBV-infected tissue and cells showed down-regulated expression of furin at both the mRNA and protein levels. In particular, the HepG2.2.15 cells showed -50% less furin mRNA expression than the HepG2 cells and the difference was statistically significant (P less than 0.05)., Conclusion: HBV may suppress the host cell's expression of furin, possibly to benefit its survival and replication in the host cell.

Objective: To express a full-length human-mouse chimeric anti-DR5 antibody from a single open reading frame with tumoricidal activity to various cancer cells., Methods: The heavy and light chains of chimeric antibody were joined by the Furin and 2A (F/2A) self-cleavage peptide and cloned into a lentiviral vector of pWPXL. Then the HEK293 cells were infected with the constructed expression vector pWPXL-HF2AL. Western blot, enzyme-linked immunosorbent assay (ELISA) and MTS assay were used to detect the chimeric antibody expression, cleavage, binding affinity to the antigen and tumoricidal activity to various tumor cells., Results: The recombinant chimeric antibody was successfully expressed from a single open reading frame in pWPXL-HF2AL construct. And it possessed a similar binding affinity to the parental murine counterpoint and strong tumoricidal activity to various cancer cells. For example, on the concentration of 3 µg/ml, it made the relative cells viability of HCT116, SMMC7721, A549 and U251 down to 20.6% ± 2.6%, 35.1% ± 2.7%, 76.1% ± 6.1% and 15.6% ± 2.0% respectively., Conclusions: The human-mouse chimeric anti-DR5 antibody of F/2A peptide is successfully expressed. Possessing a strong tumoricidal activity in various cancer cells, it may provide a novel strategy for cancer biotherapy.

Objective: To investigate the cleavage of HBV core protein in vivo by proprotein convertase furin or its family members and observe the intracellular localization of the putative cleaved product., Methods: Recombinant HBV core protein was incubated with furin under different conditions in vitro, and the reaction was checked with Western blotting. The recombinant vectors expressed the putative cleaved fragment and intact core protein (serves as control) were constructed. The stable expression cell lines were established by transfecting constructs into HepG2 cell line, for which indirect immunofluorescence staining was used by monoclonal anti-HBc against the region shared by core protein and its cleaved product .The confocal microscopy was carried out to observe the intracellular distribution., Results: HBV core protein was cleaved by furin in vitro under different tested conditions. The molecular weight of the major cleaved product just about 15,000 was in concordance with the expectation. The expressed cleaved fragment could react to the monoclonal antibody against core protein, and mainly located in cytosol in particle style just like the intact core protein., Conclusion: HBV core protein can be cleaved by furin in vitro. The major cleaved product has similar antigenicity and subcellular distribution to core protein. These data suggest that proprotein convertase furin or its family members play important roles in HBV replication regulation, and the cleaved product may be involved in antiviral immunity of HBV infection. Further investigations are imperative.

Aim: To explore the possibility of using the nontoxic form of anthrax toxin in cancer immunotherapy by LFn-MAGE3 fusion protein expression., Methods: A fusion expression vector named PET21a-LFn was constructed by inserting LFn coding senquence into PET21a. PET21a-LFn-MAGE3 fusion protein expression vector was constructed by cloning the whole MAGE-3 gene into plasmid PET21a-LFn. Q sepharose FF and Phe HP columns were employed to purify the fusion protein. The biological activity of LFn-MAGE3 was determined by cell test of repressing the cytotoxity of LF and the tests of immunofluscence of mouse macrophage., Results: The resulting plasmid expressed fusion protein LFn-MAGE3 in the soluble form in E.coli BL21, the cell tests showed that purified LFn-MAGE fusion protein was delivered into macrophage effectively with the help of PA(anthrax protective antigen)., Conclusion: The successful delivery of fusion protein into macrophages coordinated by PA may lay the foundation for its further use in cancer immunotherapy in animal experiments.