Gene expression and antitumor effects following direct interferon (IFN)-gamma gene transfer with naked plasmid DNA and DC-chol liposome complexes in mice.
Gene expression was assessed in three types of mouse solid tumors after direct injection of naked plasmid DNA encoding the luciferase gene (pCMV-Luc) and its DC-chol liposome complexes. Intratumoral injection of 5 or 100 micrograms naked pCMV-Luc into subcutaneously inoculated mouse colon tumor (CT-26), fibrosarcoma (MCA-15) and bladder carcinoma (MBT-2) resulted in significant gene expression. A DC-chol liposome formulation (5 micrograms pCMV-Luc complexed with 25 micrograms DC-chol liposome) showed lower level of gene expression in the tumor models. Based on the results using the reporter gene, we examined the antitumor effect after direct interferon-gamma (IFN-gamma) gene transfer into CT-26 tumors. A significant IFN-gamma production and growth inhibition were obtained following direct intratumoral injection of IFN-gamma gene with naked plasmid DNA (pCMV-Mu gamma). Interestingly, pCMV-Mu gamma/DC-chol liposome complexes exhibited more pronounced growth inhibitory effect despite lower IFN-gamma production. Induction of CT-26 specific antitumor immunity by IFN-gamma gene transfer was confirmed by rejection of a CT-26 tumor challenge in the mice showing complete regression of CT-26 tumors after both treatments. Further analysis demonstrated that a significant cDNA-independent induction of IFN-beta and TNF-alpha occurred following injection with the liposome complexes, suggesting a nonspecific suppressive effect on CT-26 tumor growth by these cytokines. Thus, the present study has demonstrated that tumor tissue might be a promising target for direct IFN-gamma gene transfer with plasmid-based nonviral vectors. It is also suggested that immunomodulatory effects by various cytokines could be involved in antitumor effects after direct intratumoral injection of plasmid DNA formulations.
Nomura
T
T
Department of Drug Delivery Research, Graduate School of Pharmaceutical Sciences, Kyoto University, Japan.
Yasuda
K
K
Yamada
T
T
Okamoto
S
S
Mahato
R I
RI
Watanabe
Y
Y
Takakura
Y
Y
Hashida
M
M
D000818:Animals; D016207:Cytokines / Q000235:genetics; D004247:DNA / Q000235:genetics; D015870:Gene Expression; D018014:Gene Transfer Techniques; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D015552:Injections, Intralesional; D007273:Injections, Intramuscular; D007371:Interferon-gamma / Q000235:genetics*; D008081:Liposomes; D008156:Luciferases / Q000235:genetics; D051379:Mice; D018482:Muscle, Skeletal / Q000201:enzymology; D009369:Neoplasms / Q000201:enzymology / Q000628:therapy*; D010957:Plasmids
D016207:Cytokines; D008081:Liposomes; D007371:Interferon-gamma; D004247:DNA; D008156:Luciferases