title: Preventive DNA vaccination against CEA-expressing tumors with anti-idiotypic scFv6.C4 DNA in CEA-expressing transgenic mice.
abstract: Carcinoembryonic antigen (CEA) is expressed during embryonic life and in low level during adult life. Consequently, the CEA is recognized by the immune system as a self-antigen and thus CEA-expressing tumors are tolerated. Previously, we constructed a single chain variable fragment using the 6.C4 (scFv6.C4) hybridoma cell line, which gave rise to antibodies able to recognize CEA when C57/Bl6 mice were immunized. Here, the scFv6.C4 ability to prevent the CEA-expressing tumor growth was assessed in CEA-expressing transgenic mice CEA2682. CEA2682 mice immunized with the scFv6.C4 expressing plasmid vector (uP/PS-scFv6.C4) by electroporation gave rise to the CEA-specific AB3 antibody after the third immunization. Sera from immunized mice reacted with CEA-expressing human colorectal cell lines CO112, HCT-8, and LISP-1, as well as with murine melanoma B16F10 cells expressing CEA (B16F10-CEA). Cytotoxic T lymphocytes (CTL) from uP/PS-scFv6.C4 immunized mice lysed B16F10-CEA (56.7%) and B16F10 expressing scFv6.C4 (B16F10-scFv6.C4) (46.7%) cells, against CTL from uP-immunized mice (10%). After the last immunization, 5 × 105B16F10-CEA cells were injected into the left flank. All mice immunized with the uP empty vector died within 40 days, but uP/PS-scFv6.C4 vaccinated mice (40%) remained free of tumor for more than 100 days. Splenocytes obtained from uP/PS-scFv6.C4 vaccinated mice showed higher T-cell proliferative activity than those from uP vaccinated mice. Collectively, DNA vaccination with the uP-PS/scFv6.C4 plasmid vector was able to give rise to specific humoral and cellular responses, which were sufficient to retard growth and/or eliminate the injected B16F10-CEA cells.
authors.affiliation: Research Center for Gene Therapy, Federal University of Sao Paulo, São Paulo, SP, Brazil.
authors.forename: Priscila M A
authors.initials: PMA
authors.lastname: Denapoli
authors.affiliation: Research Center for Gene Therapy, Federal University of Sao Paulo, São Paulo, SP, Brazil.
authors.forename: Bianca F
authors.initials: BF
authors.lastname: Zanetti
authors.affiliation: Research Center for Gene Therapy, Federal University of Sao Paulo, São Paulo, SP, Brazil.
authors.forename: Adara A
authors.initials: AA
authors.lastname: Dos Santos
authors.affiliation: Department of Biophysics, Federal University of Sao Paulo, Rua Mirassol, 207, São Paulo, SP, 04044-010, Brazil.
authors.forename: Jane Z
authors.initials: JZ
authors.lastname: de Moraes
authors.affiliation: Research Center for Gene Therapy, Federal University of Sao Paulo, São Paulo, SP, Brazil. sang.han@unifesp.br.|Department of Biophysics, Federal University of Sao Paulo, Rua Mirassol, 207, São Paulo, SP, 04044-010, Brazil. sang.han@unifesp.br.
authors.forename: Sang W
authors.initials: SW
authors.lastname: Han
mesh_terms: D000818:Animals; D002272:Carcinoembryonic Antigen / Q000276:immunology*; D015179:Colorectal Neoplasms / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control*; D004195:Disease Models, Animal; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D014162:Transfection; D019444:Vaccines, DNA / Q000008:administration & dosage* / Q000276:immunology*
chemical_list: D002272:Carcinoembryonic Antigen; D019444:Vaccines, DNA
keywords: Anti-idiotypic antibody; Carcinoembryonic antigen; Colorectal cancer; DNA vaccine; Immunological tolerance; Single-chain fragment variable