Objective: To evaluate the therapeutic effect and the expression level of a tumor-specific replication-competent adenovirus and a replication-defective adenovirus expression mouse recombinant IL-12 (mIL-12) gene on hepatocellular carcinoma (HCC) in vitro.
Methods: The cytotoxicity of replication-competent adenovirus with E1B-55 000 attenuated CNHK200-mIL12 and ONYX-015 (dl1520), and replication-defective adenovirus Adv-mIL12 were evaluated by MTT and replication assay in two HCC cell lines (HepG2 and Hep3B) and human normal hepatocyte line (LO2). Western blot and ELISA were used to determine the expression level of mIL-12.
Results: CNHK200-mIL12 replicated in HepG2 and Hep3B with an increase of 3,160-fold and 630-fold respectively in 96 h post-infection. CNHK200-mIL12 could kill HepG2 and Hep3B cells at a very low MOI (Multiplicity of Infection) and in short time course (HepG2:MOI = 0.2, on day 4; Hep3B:MOI = 0.005, on day 2), while it had no significant effect on LO2. Furthermore, the expressing level of mIL-12 in CNHK200-mIL12 treated HCC cell lines was much higher than that in Adv-mIL12 treated one (HepG2 101-fold, Hep3B 20-fold respectively).
Conclusion: Replication-competent adenovirus is more effective than replication-defective adenovirus in both cytotoxicity and efficiency of gene transfer in HCC, and holds great promise in the area of HCC therapy.