Electroporation-mediated interleukin-12 gene therapy for hepatocellular carcinoma in the mice model

Applications of nonviral vectors for gene transfer into tumors in vivo have been Limited by the relatively low expression levels of the transferred ge ne. The aim of this study is to evaluate the efficacy of electroporation-me diated interleukin-12 (IL-12) gene therapy For hepatocellular carcinoma (HC C), First, we investigated the optimal conditions of electric pulses (volta ge, pulsing duration, numbers of shocks) of in vivo electroporation for gen e transfer into HCC established by s.c. implantation of MH134 cells to C3H mice. This process made use of plasmid DNA that express the luciferase gene . We concluded that the optimal conditions for the electric pulses are as f ollows: voltage at 150 V; pulsing duration at 50 ms; nonpulsing duration at 950 ms; and the number of shocks at 10, Second, we tried to treat s.c. HCC by electroporation using plasmid DNA that expresses the murine interleukin -12 (mlL12) gene. Intratumoral administration of the mIL-12 vector elevated serum IL-12 and IFN-gamma and significantly inhibited the growth not only of HCC into which the mlL-12 vector had been directly transferred, but also of the distant HCC, In addition, intratumoral administration of the mIL-12 vector inhibited spontaneous lung metastasis and delayed establishment of HCC injected 3 days after mIL-12 gene therapy. The IL-12 gene therapy induc ed more lymphocyte infiltration by NK cells, CD3(+) tells, and Mac-1 positi ve cells into the tumor and reduced the number of microvessels. Therefore, more terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling- positive tumor cells were found. These results demonstrate that gene therap y for HCC by electroporation in vivo using IL-12 is very efficient and is t hus promising for further clinical trial.