Anti-tumor effect of in vivo IL-2 and GM-CSF electrogene therapy in murine hepatoma model.
BACKGROUND
We evaluated the effect of in vivo electrogene therapy (EGT), a newly-developed gene transfer method using electroporation on the induction of anti-cancer immunity.


METHODS
The in vivo EGT was carried out by direct injection of plasmid DNAs encoding mouse interleukin-2 (IL-2) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in a subcutaneous murine hepatoma model of 1MEA.7R.1 cells. Six electric pulses were generated in situ from a square-wave electroporator fitted with a circular, six-needle electrode array. 1MEA.7R1 cells in vitro were modified to secret IL-2 (1MEA.7R.1/IL-2 cells).


RESULTS
The 1MEA.7R.1/IL-2 cells had a similar cell doubling-time as their parent cells but showed a much slower growth rate on Balb/C mice. One, or 3 rounds of single gene EGT with IL-2 gene showed a dose-responsive effect of growth retardation. Co-administration of 3 rounds of IL-2/GM-CSF double genes EGT had a stronger growth inhibition effect than 3 rounds of IL-2 single gene EGT. Three rounds of IL-2/GM-CSF EGT rendered the tumor to a growth rate of stably transfected 1MEA.7R.1/IL-2 cells. Seven rounds of IL-2/GM-CSF EGT markedly inhibited the tumor growth. Reverse transciptase-polymerase chain reaction confirmed the expression of IL-2, GM-CSF and interferon-gamma within treated tumors. Systemic inhibitory effects can be demonstrated from tumor-re-challenged experiments on mice which received 3 rounds of double-gene EGT. The T cell proliferation assay revealed an increased T cell proliferation in double-gene EGT-treated mice.


CONCLUSIONS
This experiment showed that partial systemic immunity can be provoked by IL-2/GM-CSF double-gene EGT. These findings suggest that our immuno-gene therapy protocol has the potential for future clinical applications.
Chi
Chau-Hwa
CH
Department of Veterinary Medicine, National Taiwan University, Taiwan.
Wang
Yu-Shan
YS
Lai
Yen-Shuae
YS
Chi
Kwan-Hwa
KH
D000818:Animals; D018274:Electroporation / Q000379:methods; D015316:Genetic Therapy / Q000379:methods*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D007376:Interleukin-2 / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D008114:Liver Neoplasms, Experimental / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000628:therapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics
D007376:Interleukin-2; D012333:RNA, Messenger; D016178:Granulocyte-Macrophage Colony-Stimulating Factor