This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Dickerson, E. B. Articles by Helfand, S. C. Search for Related Content PubMed PubMed Citation Articles by Dickerson, E. B. Articles by Helfand, S. C.

---

Angiogenesis, Metastasis, and the Cellular Microenvironment

Enhancement of the Antiangiogenic Activity of Interleukin-12 by Peptide Targeted Delivery of the Cytokine to _vß₃ Integrin¹

Departments of ¹ Medical Sciences, ² Pathobiological Sciences, and ³ Surgical Sciences, School of Veterinary Medicine; ⁴ Department of Biostatisticss and Medical Informatics; and ⁵ Laboratory of Developmental Biology, Department of Zoology; and ⁶ Comprehensive Cancer Center, University of Wisconsin, Madison, Wisconsin

Requests for reprints: Stuart C. Helfand, 2015 Linden Drive, Madison, WI 53706. Phone: 608-263-4548; Fax: 608-265-8020. Email: helfands{at}svm.vetmed.wisc.edu

We engineered a fusion protein, mrIL-12vp [mouse recombinant interleukin (IL)-12 linked to vascular peptide], linking the vascular homing peptide CDCRGDCFC (RGD-4C), a ligand for _vß₃ integrin, to mrIL-12 to target IL-12 directly to tumor neovasculature. The fusion protein stimulated IFN- production in vitro and in vivo, indicating its biological activity was consistent with mrIL-12. Immunofluorescence techniques showed mrIL-12vp specifically bound to _vß₃ integrin-positive cells but not to _vß₃ integrin-negative cells. In corneal angiogenesis assays using BALB/c mice treated with either 0.5 µg/mouse/d of mrIL-12vp or mrIL-12 delivered by subcutaneous continuous infusion, mrIL-12vp inhibited corneal neovascularization by 67% compared with only a slight reduction (13%) in angiogenesis in the mrIL-12-treated animals (P = 0.008). IL-12 receptor knockout mice given mrIL-12vp showed a marked decrease in the area of corneal neovascularization compared with mice treated with mrIL-12. These results indicate that mrIL-12vp inhibits angiogenesis through IL-12-dependent and IL-12-independent mechanisms, and its augmented antiangiogenic activity may be due to suppression of endothelial cell signaling pathways by the RGD-4C portion of the fusion protein. Mice injected with NXS2 neuroblastoma cells and treated with mrIL-12vp showed significant suppression of tumor growth compared with mice treated with mrIL-12 (P = 0.03). Mice did not show signs of IL-12 toxicity when treated with mrIL-12vp, although hepatic necrosis was present in mrIL-12-treated mice. Localization of IL-12 to neovasculature significantly enhances the antiangiogenic effect, augments antitumor activity, and decreases toxicity of IL-12, offering a promising strategy for expanding development of IL-12 for treatment of cancer patients.

Key Words: interleukin-12 • angiogenesis • _vß₃ integrin • endothelium • RGD

This article has been cited by other articles:

				L. Cao, P. Du, S.-H. Jiang, G.-H. Jin, Q.-L. Huang, and Z.-C. Hua Enhancement of antitumor properties of TRAIL by targeted delivery to the tumor neovasculature Mol. Cancer Ther., April 1, 2008; 7(4): 851 - 861. [Abstract] [Full Text] [PDF]

				W. W. Overwijk, K. E. de Visser, F. H. Tirion, L. A. de Jong, T. W. H. Pols, Y. U. van der Velden, J. G. van den Boorn, A. M. Keller, W. A. Buurman, M. R. Theoret, et al. Immunological and Antitumor Effects of IL-23 as a Cancer Vaccine Adjuvant J. Immunol., May 1, 2006; 176(9): 5213 - 5222. [Abstract] [Full Text] [PDF]