Interleukin 12 Gene Transfer into Skin Distant from the Tumor Site Elicits Antimetastatic Effects Equivalent to Local Gene Transfer

Abstract

We have reported that particle-mediated interleukin 12 (IL-12) gene transfer into the skin overlying the local tumor inhibits systemic metastases. To further characterize this effect, we compared the antitumor and antimetastatic effects of IL-12 cDNA delivered at the local tumor site versus at a site distant from the primary tumor, in a spontaneous metastasis model of LLC-F5 tumor. Local IL-12 gene delivery into the skin overlying the intradermal tumor (local IL-12 treatment) on days 7, 9, and 11 after tumor implantation resulted in the most suppression of the growth of the primary LLC-F5 tumor, whereas IL-12 gene transfer into the skin distant from the tumor (distant IL-12 treatment) was less effective. In contrast, both local IL-12 and distant IL-12 treatment, followed by tumor excision, inhibited lung metastases to a similar extent, resulting in significantly extended survival of test mice. The results of in vivo studies using depleting anti-asialo GM1 antibody and anti-CD4/anti-CD8 monoclonal antibodies, or neutralizing anti-interferon gamma (IFN-gamma) monoclonal antibody demonstrated that natural killer (NK) cells, CD8(+) T cells, and IFN-gamma contributed to the antimetastatic effects in both treatment groups. Furthermore, the levels of mRNA expression of vascular endothelial growth factor and matrix methalloproteinase 9 at the tumor microenvironment were suppressed after both local and distant IL-12 treatment. These results suggest that the current particle-mediated IL-12 gene delivery in the spontaneous LLC-F5 metastasis model can confer antimetastatic activities, irrespective of the gene transfection site, via a combination of several mechanisms involving CD8(+) T cells, NK cells, IFN-gamma, and antiangiogenesis.

IFN-γ Acts on T Cells to Induce NK Cell Mobilization and Accumulation in Target Organs

“…Administration of IL-12 was shown to inhibit systemic metastases of 3LL in an IFN-␥-and NK-dependent manner (26). NK cells play a role in reducing metastasis.…”

Intratumor murine interleukin-12 gene therapy suppressed the growth of local and distant Ewing's sarcoma

“…The systemic administration of IL-12 protein has been shown to inhibit tumor growth and prevent spontaneous metastases to lung and lymph nodes in several different animal tumor models. 12,[22][23][24][25] In clinical trials, although tumor regression was documented the systemic administration of IL-12 protein resulted in undesirable effects. 26 These toxicities were linked to IFN-g.…”

Molecular strategies for improving cytokine transgene expression in normal and malignant tissues

“…Murine IL-12 subunits were cloned from mouse cDNA libraries as previously described. 32 The four murine IL-12 expression vectors were constructed as follows: the first and second contain the p35 and p40 coding sequence arranged in tandem either in the same orientation or head-to-head orientation, with each subunit gene driven by its own CMV promoter (a, b). The third vector contains a single operon driven by a CMV promoter, with p35 and p40 coding sequences linked by an IRES sequence, obtained from Novagen, Madison, WI, USA (c).…”

“…This was demonstrated by their capacity to elicit CTL or histological inflammatory activity and potent antitumor activities effectively. 12,13,29,[30][31][32] Together with the findings of the relative capacities of different cDNA constructs in the current study, we believe that these results can be usefully employed by researchers for the proper and specified use of 3 0 UTR deletion for cytokine expression vectors in a clinically relevant study, that is, different as well as the same cytokine species can differ drastically in transgene expression under different in vivo and ex vitro conditions, and hence specific cytokine expression vectors do need to be carefully tested in target or related cells/tissues before clinical studies.…”