New polymer carrier targeting to angiogenic endothelial cells will be designed. The cationic polymer, polyethylenimine (PEI) will be conjugated with the avb31avb5 integrin binding RGD-4C peptide, ACDCRGDCFC via hydrophilic polyethylene glycol (PEG) spacer. This designed carrier will be used for the delivery of antiangiognesis plasmids. The significant over expression of alpha-v-Beta3 and alpha-v-Beta5 integrins in angiogenic endothelial cells provides specific targeting of solid tumors compared to normal tissue, PEI condenses DNA and is endosomotropic, thereby protecting and delivering antiangiogenic plasmid DNA into target cells. In addition, the PEG spacer increases the solubility of the carrier and reduces PEI toxicity. Furthermore, this polymeric carrier is nonimmunogenic and for practical purposes can be easily mass-produced. Using the PEI-PEG-RGD carrier, preliminary data shows high specificity and transfection of plasmid DNA to the target cells. Plasmid constructs will be generated containing the endogeneous angiogenic inhibitors, solublized Flt-1 and FIk-1 receptors and the newly constructed therapeutic gene, pDHFR-p53. After extensive characterization, in vitro studies, rat malignant glioma, and murine lewis lung carcinoma animal models will be used (local and systemic delivery routes) with the carrier. A number of endogenous inhibitors targeting tumor vasculature have been studied and their systemic administration in animals suppresses the growth of tumor and metastases. However, production of recombinant proteins has proven to be difficult and high doses are required for effective treatment. In addition, systemic protein therapy includes repeated injections for prolonged treatment, which is inconvenient for administration and costly. Gene therapy, utilizing these endogenous angiogenesis inhibitors, can alleviate these problems. The results will be valuable assets to provide criteria for gene delivery in the treatment of cancer using antiangiogenesis genes.