AAV-mediated human PEDF inhibits tumor growth and metastasis in murine colorectal peritoneal carcinomatosis model

Abstract

Doc number: 129

Abstract

Background: Angiogenesis plays an important role in tumor growth and metastasis, therefore antiangiogenic therapy was widely investigated as a promising approach for cancer therapy. Recently, pigment epithelium-derived factor (PEDF) has been shown to be the most potent inhibitor of angiogenesis. Adeno-associated virus (AAV) vectors have been intensively studied due to their wide tropisms, nonpathogenicity, and long-term transgene expression in vivo . The objective of this work was to evaluate the ability of AAV-mediated human PEDF (hPEDF) as a potent tumor suppressor and a potential candidate for cancer gene therapy.

Methods: Recombinant AAV₂ encoding hPEDF (rAAV₂ -hPEDF) was constructed and produced, and then was assigned for in vitro and in vivo experiments. Conditioned medium from cells infected with rAAV₂ -hPEDF was used for cell proliferation and tube formation tests of human umbilical vein endothelial cells (HUVECs). Subsequently, colorectal peritoneal carcinomatosis (CRPC) mouse model was established and treated with rAAV₂ -hPEDF. Therapeutic efficacy of rAAV₂ -hPEDF were investigated, including tumor growth and metastasis, survival time, microvessel density (MVD) and apoptosis index of tumor tissues, and hPEDF levels in serum and ascites.

Results: rAAV₂ -hPEDF was successfully constructed, and transmission electron microscope (TEM) showed that rAAV₂ -hPEDF particles were non-enveloped icosahedral shape with a diameter of approximately 20 nm. rAAV₂ -hPEDF-infected cells expressed hPEDF protein, and the conditioned medium from infected cells inhibited proliferation and tube-formation of HUVECs in vitro . Furthermore, in CRPC mouse model, rAAV₂ -hPEDF significantly suppressed tumor growth and metastasis, and prolonged survival time of treated mice. Immunofluorescence studies indicated that rAAV₂ -hPEDF could inhibit angiogenesis and induce apoptosis in tumor tissues. Besides, hPEDF levels in serum and ascites of rAAV₂ -hPEDF-treated mice were significant higher than those in rAAV₂ -null or normal saline (NS) groups.

Conclusions: Thus, our results suggest that rAAV₂ -hPEDF may be a potential candidate as an antiangiogenic therapy agent.