Der Einsatz von aufgereinigten VP22-Fusionsproteinen als Basis einer neuartigen, Peptid-vermittelten und systemischen Therapie des Pankreaskarzinoms

Abstract

We constructed a prokaryotic vector expressing a truncated Herpes simplex virus (HSV-1)-VP22 fused to the Enhanced Green Fluorescent Protein (EGFP) and purified this fusion protein from E.coli cultures using Nickel resin. Application of purified VP22-EGFP protein to pancreatic carcinoma cells showed a highly efficient uptake and resulted in green fluorescence predominantly located in nuclei of treated cells. In comparison to common gene therapy protocols such as retroviral transduction, cells treated with VP22-EGFP fusion protein displayed a homogeneous shift of fluorescence levels as shown by FACS analysis, implying that nearly the entire cell population was successfully protein transduced by purified VP22-EGFP. The expression pattern in vitro displayed a time dependence, resulting in a complete uptake of VP22-EGFP from the medium into nuclei of pancreatic carcinoma cells after 18 hours treatment. By increasing the concentration of VP22-EGFP, we were able to nearly linearly dose the fluorescence levels of treated cells. Furthermore, purified VP22-EGFP protein efficiently translocated into deeper layers of pancreatic tumor cell spheroids and xenotransplanted pancreatic tumors in SCID mice. We conclude that the direct application of purified VP22 fusion proteins offers a new, peptide-mediated therapy for pancreatic cancer implying the remarkable opportunity to dose specific catatonic effects induced by fused tumor-suppressing proteins.