Investigation of a plasmid containing a novel immunotoxin VEGF165‐PE38 gene for antiangiogenic therapy in a malignant glioma model

Abstract

Inhibition of tumor neovascularization has profound effects on the growth of solid tumors. Our previous studies have shown the effect of VEGF165-PE38 recombinant immunotoxin on proliferation and apoptosis in human umbilical vein endothelial cells in vitro. In this study, we explored the direct inhibition of angiogenesis in chick chorioallantoic membrane and antiangiogenic therapy in a malignant glioma model. HEK293 cells were transfected with the pVEGF165PE38-IRES2-EGFP plasmid. ELISA was used to confirm the expression of VEGF165-PE38 in the transfected cells. These cells released 1396 6 131.9 pg VEGF165-PE38/1310 4 cells/48 h into the culture medium and the supernatant was capable of inhibiting the growth of capillary-like structures in chick chorioallantoic membrane assay. In a murine malignant glioma model, plasmid was directly administered via multiple local intratumoral delivery. After day 16 the tumor volume in mice treated with pVEGF165PE38-IRES2-EGFP was significantly lower than that in mice in the control groups. Immunohistochemistry studies showed that the treated group had decreased expression of CD31. ). Immunohistochemistry analysis indicated that immunotoxin VEGF165-PE38 was distributed in the treated group in malignant glioma tissue. Our findings provide evidence that the in vivo production of VEGF165-PE38 through gene therapy using a eukaryotic expression plasmid had potential antiangiogenic activity in malignant glioma in vivo.A promising approach to cancer therapy is based on an attack on new blood vessels rather than a direct attack on cancer cells. This approach may, thus, multiply the effects of anticancer drugs. 1 In addition, such a stromal therapy approach carries the prospect of being less prone to resistance mechanisms theoretically due to genetic stability.2 Several reports have indicated that therapies aimed at tumor vasculature such as angiostatin, endostatin, humanized monoclonal antibody directed against vascular endothelial growth factor (VEGF; bevacizumab) and other small molecule receptor tyrosine kinase inhibitors (sorafenib and sunitinib) 3 can lead to rapid regression of existing tumors. However, these inhibitors of angiogenesis do not destroy tumor vasculature, which can regenerate when these drugs are discontinued.4 These concerns raise the following questions with respect to improving antiangiogenic therapy: is it possible to find a therapeutic strategy aimed at destroying tumor vasculature endothelial cells but not inhibiting normal vasculature endothelial cell growth? Is it possible to completely destroy the tumor vasculature network system?Immunotoxin is a hybrid molecule that consists of a targeting moiety and a toxic moiety. 5,6 Pseudomonas exotoxin (PE) is often used as a toxic moiety because it is highly toxic to eukaryotic cells. Monoclonal antibodies as well as cytokines and

A novel bispecific immunotoxin delivered by human bone marrow-derived mesenchymal stem cells to target blood vessels and vasculogenic mimicry of malignant gliomas

“…MSCs are effectively used as cell carriers for immunotoxin gene therapy 20,21. In the current investigation, we designed and synthesized a BIT, VEGF 165 -ephrin A1-PE38KDEL, consisting of truncated Pseudomonas exotoxin (PE) and two different ligands, specifically, in which VEGF 165 targeted the VEGFR and ephrin A1 targeted the EphA2 receptor.…”

Species-Dependent Functionality of the Human Cytolytic Fusion Proteins Granzyme B-H22(scFv) and H22(scFv)-Angiogenin in Macrophages

“…Among these are the common immunotoxins, which specifically deliver toxic components into diseased target cells [1,2]. These chimeric proteins contain a specific cell-binding moiety, which can either be a ligand, a full-length antibody, or a fragment thereof, coupled to an apoptosis-inducing molecule [3][4][5][6]. After binding to the target cell, the immunotoxin is internalized followed by endosomal processing and final release of the toxin into the cytosol, where it catalytically induces cell death [7].…”

Therapeutic targets and recent advances in protein immunotoxins

“…Targeting angiogenesis, which is the key to metastasis is another promising approach. Vascular endothelial growth factor (VEGF-PE38) based gene therapy reduced the microvessel density significantly in a malignant glioma model [8].…”