Adenovirus-interleukin-12-mediated tumor regression in a murine hepatocellular carcinoma model is not dependent on CD1-restricted natural killer T cells.
The cytokine interleukin-12 (IL-12) has shown potent antitumor activity in several tumor models. Recently, natural killer (NK) T cells have been proposed to mediate the antitumor effects of IL-12. In this study, the antitumor response of IL-12 was investigated in a gene therapeutic model against s.c. growing mouse hepatocellular carcinomas using an adenoviral vector expressing murine IL-12 (AdVmIL-12). An adenoviral-based system was chosen because of the ability of adenoviruses to transduce dividing and nondividing cells and because of their high transduction efficiencies. Our goals were to examine the efficacy of AdVmIL-12 in a hepatocellular carcinoma model and to investigate the mechanism of the AdVmIL-12-mediated antitumor response with specific interest in the role of NK T cells. Our studies demonstrate that intratumoral AdVmIL-12-mediated regression of s.c. hepatocellular tumors is associated with rapid antitumor responses. AdVmIL-12 treatment was associated with an immune cellular infiltrate consisting of CD4 and CD8 T lymphocytes, macrophages, NK cells, and NK T cells. Antibody ablation of CD4 and CD8 T cells and use of NK cell-defective beige mice failed to abrogate the response to AdVmIL-12. Studies in T-cell- and B-cell-deficient severe combined immunodeficient and recombinase activating gene-2-deficient mice and T-cell-, B-cell-, and NK cell-defective severe combined immunodeficient/beige mice also failed to abrogate this response. AdVmIL-12 retained potent antitumor activity in mice with specific genetic defects in immune cellular cytotoxicity (perforin knockout mice) and costimulation (CD28 knockout mice). Use of mice with specific NK T cell deficiencies, Valpha14 T-cell receptor and CD1 knockout mice, also failed to abrogate the response to AdVmIL-12. Histological and immunohistochemical studies of AdVmIL-12-treated tumors showed extensive inhibition of neovascularization and a marked decrease in factor VIII-stained endothelial cells. Our studies indicate that the antitumor response of AdVmIL-12 is independent of direct cytotoxic cellular immunity (specifically, the function of NK T cells) and suggest that the initial mechanisms of AdVmIL-12-mediated tumor regression involve inhibition of angiogenesis.
Andrews
K J
KJ
Division of Surgical Oncology, University of California Los Angeles, 90095, USA.
Ribas
A
A
Butterfield
L H
LH
Vollmer
C M
CM
Eilber
F C
FC
Dissette
V B
VB
Nelson
S D
SD
Shintaku
P
P
Mekhoubad
S
S
Nakayama
T
T
Taniguchi
M
M
Glaspy
J A
JA
McBride
W H
WH
Economou
J S
JS
D000256:Adenoviridae / Q000235:genetics / Q000276:immunology; D000818:Animals; D018949:Antigens, CD1 / Q000276:immunology*; D018106:CD28 Antigens / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D004195:Disease Models, Animal; D006801:Humans; D016867:Immunocompromised Host / Q000276:immunology; D018664:Interleukin-12 / Q000235:genetics / Q000276:immunology*; D007694:Killer Cells, Natural / Q000276:immunology*; D008114:Liver Neoplasms, Experimental / Q000276:immunology* / Q000628:therapy; D008562:Membrane Glycoproteins / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D016513:Mice, SCID; D009389:Neovascularization, Pathologic / Q000517:prevention & control; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D013601:T-Lymphocytes / Q000276:immunology*
D018949:Antigens, CD1; D018106:CD28 Antigens; D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin; D018664:Interleukin-12