title: Transfection of interleukin-12 cDNAs into tumor cells induces cytotoxic immune responses against native tumor: implications for tumor vaccination.
abstract: Interleukin-12 (IL-12) is a heterodimeric cytokine that is central to the development of T helper 1-dependent cellular immunity. Although this cytokine has potential therapeutic application as an antineoplastic agent, the systemic infusion of IL-12 has led to toxic fatalities; hence, restriction of expression of IL-12 to the microenvironment of target tumor cells has obvious appeal. In this study, we examined whether tumor cells that were liposome-transfected with IL-12 could enhance the induction of cytolytic lymphocyte immunity to the native tumor. The plasmid expression vector that we used has several useful features including replication to high copy number as an episome and a polycistronic message enabling the production of both the p35 and p40 subunits of IL-12 without alternative splicing; up to 3 ng/mL/10(6)/48 hours of IL-12 was produced following transfection. Tumor cells transfected with IL-12 were superior to untransfected cells in the induction of lymphocyte-mediated cytolysis. IL-12 transfectants induced a heterogeneous population of natural killer, lymphokine activated killer, and cytolytic T lymphocytes, the latter of which exhibited tumor-specific activity. Our studies suggest that liposome-mediated transfection of tumor cells with an episomal, high copy number plasmid vector expressing both IL-12 subunits is a promising approach to cancer vaccination, a strategy that could be implemented ex vivo in treating malignancies such as metastatic ovarian cancer.
authors.affiliation: Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: T
authors.initials: T
authors.lastname: Hoshino
authors.forename: Y Z
authors.initials: YZ
authors.lastname: Jiang
authors.forename: D
authors.initials: D
authors.lastname: Dunn
authors.forename: D
authors.initials: D
authors.lastname: Paul
authors.forename: M
authors.initials: M
authors.lastname: Qazilbash
authors.forename: K
authors.initials: K
authors.lastname: Cowan
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Barrett
authors.forename: J
authors.initials: J
authors.lastname: Liu
mesh_terms: D019496:Cancer Vaccines / Q000008:administration & dosage* / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D018076:DNA, Complementary; D000229:Dependovirus / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D005822:Genetic Vectors; D006801:Humans; D018664:Interleukin-12 / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D008214:Lymphocytes / Q000276:immunology; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D019496:Cancer Vaccines; D018076:DNA, Complementary; D018664:Interleukin-12