955. Transduction Efficiency Screening for 7 Different AAV Serotypes in 12 Human Cancer Cell Lines and 2 Xenograft Animal Models

Abstract

Over the past several years, viral and non-viral gene delivery systems have been intensively developed to establish an ideal delivery vector for cancer gene therapy. Among the large variety of virus vectors currently being developed, the vector based on recombinant AAV (rAAV) is one of those that are closest to the ideal vector due to the following features; the lack of pathogenicity and toxicity, ability to infect dividing and non-dividing cells of various tissue origins, a very limited host immune response and long-term persistent expression. However, there is concern that two major obstacles of AAV serotype 2 (AAV2), the relative paucity of AAV receptors on certain cell types and the presence of pre-existing immunity to AAV2 in humans might limit its clinical applications in humans. To overcome these limitations, we first investigated in vitro transduction efficiencies for 7 different AAV serotypes (AAV1 |[ndash]| AAV6, AAV8) in 12 human tumor cell lines (MKN74, AGS, NCI-H460, HT1080, HepG2, SK-Hep1, HCT-116, 5637, UMUC3, HeLa, DU145 and MCF7). We employed |[ldquo]|pseudotyped|[rdquo]| AAV vector systems, in which rAAV2 vector genomes containing the CMV promoter/ enhancer, the green fluorescent protein (GFP) cDNA and SV40 poly (A) signal, flanked by AAV2 ITR sequences are cross-packaged into the capsid proteins of the other AAV serotypes (several plasmids are kindly provided by Dr. Katherine A. High, University of Pennsylvania Medical Center). As we reported previously, the efficiency of rAAV2 infection into most of the tested cancer cell lines was significantly high (>90%), whereas the transduction efficiencies for other 5 different rAAV serotypes were varied and greatly low. On the other hand the efficiency of rAAV5 transduction in various tumor cell lines were comparably high, mostly similar to that of rAAV2. Using the xenograft nude mice implanted with either NCI-H460 or HCT-116 cancer cells, we also studied in vivo transduction efficiency for several pseudotyped rAAV vectors, which were shown to have a host range different from rAAV2. Taken altogether our results suggest that the pseudotyped rAAV5 vector can be developed as one of the most efficient gene delivery systems for cancer gene therapy to overcome the anti-AAV2 immune response. (This study was supported by the grant from the Ministry of Science and Technology (M10534040005-05N3404-00511), Seoul, and the Chung-Buk Pioneering Bioindustry R&D Grant, Chung-Buk, Korea.)