In vivo antiangiogenic gene therapy mediated by electrotransfer in a transgenic mouse model of intraocular tumor with metastases.

Abstract

Abstract: : Purpose: To investigate inhibitory effect of several human plasminogen proteolytic fragments, known as kringle (K), on metastatic dissemination in TRP–1/SV40 Tag transgenic mice, a model of choroidal melanoma wich develop eye tumors with brain metastases. Methods: Plasmidic vectors encoding K1–3, K1–3HSA (a fusion protein between angiostatin K1–3 and human serum albumin), K1–5, K1–5HSA and K5HSA were successively tested. Plasmid DNA delivery was achieved by electrotransfer in skeletal muscle fibers of newborn transgenic mice. The amount of angiogenic inhibitor present in the sera of mice was quantified by a sandwich ELISA. Brains of TRP–1/SV40 mice were removed 62 days after birth and processed, and HES–stained section were examined. Results: Histological examinations of the brain demonstrated a marked reduction (p=0,01) of the volume of metatases in the K1–3HSA (1,68 mm3 ± 1,42) and K1–5HSA (1,62 mm3 ± 3) electrotransfer group relative to the control group (6,81 mm3 ± 8,14). Metasatses in K1–3, K1–5 and K5HSA–treated mice was also smaller than the control metastases but the difference did not reach statistical significance. A sufficient biologic half–life achieve by K1–3HSA and K1–5HSA, leading to a higher concentration in the sera, seems to be a critical point in their antiangiogenic activity. Conclusions: Electrotransfer of plasmid encoding K1–3HSA and K1–5HSA in skeletal muscle is efficient and reach to a significant reduction in metastatic widespread in transgenic TRP–1/SV40 mice. This approach could be relevant for a therapeutic way of preventing the development of metastases derived from intraocular tumors.

Keywords: gene transfer/gene therapy • oncology • tumors