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

Abstract

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.