Human CD4+ T cells present within the microenvironment of human lung tumors are mobilized by the local and sustained release of IL-12 to kill tumors in situ by indirect effects of IFN-gamma.
By implanting nondisrupted pieces of human lung tumor biopsy tissues into SCID mice, it has been possible to establish viable grafts of the tumor, as well as the tumor-associated microenvironment, including inflammatory cells, fibroblasts, tumor vasculature, and the extracellular matrix. Using this xenograft model, we have evaluated and characterized the effects of a local and sustained release of human rIL-12 (rhIL-12) from biodegradable microspheres. In response to rhIL-12, the human CD45+ inflammatory cells present within the xenograft mediate the suppression or the complete arrest of tumor growth in SCID mice. Analysis of the cellular events reveals that human CD4+ and CD8+ T cells are induced by rhIL-12 to produce and secrete IFN-gamma. Serum levels of human IFN-gamma in mice bearing rhIL-12-treated tumor xenografts correlate directly with the degree of tumor suppression, while neutralizing Abs to human IFN-gamma abrogate the IL-12-mediated tumor suppression. Gene expression profiling of tumors responding to intratumoral rhIL-12 demonstrates an up-regulation of IFN-gamma and IFN-gamma-dependent genes not observed in control-treated tumors. Genes encoding a number of proinflammatory cytokines, chemokines (and their receptors), adhesion molecules, activation markers, and the inducible NO synthase are up-regulated following the introduction of rhIL-12, while genes associated with tumor growth, angiogenesis, and metastasis are decreased in expression. NO contributes to the tumor killing because an inhibitor of inducible NO synthase prevents IL-12-induced tumor suppression. Cell depletion studies reveal that the IL-12-induced tumor suppression, IFN-gamma production, and the associated changes in gene expression are all dependent upon CD4+ T cells.
Hess
Stephen D
SD
Department of Microbiology, State University of New York, Buffalo, NY 14214, USA.
Egilmez
Nejat K
NK
Bailey
Nicola
N
Anderson
Timothy M
TM
Mathiowitz
Edith
E
Bernstein
Steven H
SH
Bankert
Richard B
RB
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000517:prevention & control; D002465:Cell Movement / Q000235:genetics / Q000276:immunology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000276:immunology; D006084:Graft Rejection / Q000235:genetics / Q000276:immunology / Q000473:pathology; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000276:immunology / Q000473:pathology; D007371:Interferon-gamma / Q000096:biosynthesis / Q000502:physiology* / Q000627:therapeutic use; D018664:Interleukin-12 / Q000378:metabolism* / Q000627:therapeutic use; D008175:Lung Neoplasms / Q000235:genetics / Q000276:immunology* / Q000378:metabolism / Q000517:prevention & control*; D016040:Lung Transplantation / Q000276:immunology / Q000473:pathology; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology* / Q000378:metabolism; D008297:Male; D051379:Mice; D016513:Mice, SCID; D009569:Nitric Oxide / Q000502:physiology; D011994:Recombinant Proteins / Q000378:metabolism / Q000627:therapeutic use; D014183:Transplantation, Heterologous
D011994:Recombinant Proteins; D018664:Interleukin-12; D009569:Nitric Oxide; D007371:Interferon-gamma