Efficacy of recombinant adeno-associated viral vectors serotypes 1, 2, and 5 for the transduction of pancreatic and colon carcinoma cells.
BACKGROUND
The development of efficient and specific vector systems remains a central issue in gene therapy. Several different adeno-associated virus (AAV) serotypes have so far been characterized so far which show different tissue tropisms.


METHODS
The vectors used here contained AAV2 transgene cassette containing green fluorescent protein (GFP) in AAV1, AAV2, or AAV5 capsids, producing the recombinant pseudotypes rAAV2/1, rAAV2/2, and rAAV2/5. The transduction efficiency of the different pseudotyped AAV vectors was tested in vitro in pancreatic and colon cancer cells lines (HT-29, BXPC3, and Hs766T).


RESULTS
For all three serotypes, the percentage of GFP-positive cells was below 10% at multiplicities of infection (MOI) 100 rAAV vectors when used alone for infection. However, transduction efficiency for rAAV vectors increased dramatically when the cells were co-infected with wild-type adenovirus (wtAd). The percentage of GFP-positive cells ranged from 19.8-65.3% for AAV2/1 and 16.9-70.2% for AAV2/5, respectively. It was highest for rAAV2/2, at 40.9-88.4%. Variation between the cell lines was observed, with BXPC3 scoring the highest transduction rates and HT-29 the lowest.


CONCLUSIONS
This study indicates that vectors based on distinct AAV serotypes 1, 2, and 5 all transduce pancreatic and colon cell lines poorly when used alone. Co-infection with wtAd increase transduction rates dramatically indicating that slow second-strand synthesis is a reason for the poor transduction efficiency. Due to the poor transduction rates, none of the rAAV serotypes tested here seem to be feasible for the treatment of malignant tumors.
Teschendorf
Christian
C
Department of Internal Medicine, Knappschaftskrankenhaus, University of Bochum, 44892 Bochum, Germany. christian.teschendorf@rub.de
Emons
Barbara
B
Muzyczka
Nicholas
N
Graeven
Ullrich
U
Schmiegel
Wolff
W
D002460:Cell Line; D003110:Colonic Neoplasms / Q000628:therapy*; D000229:Dependovirus / Q000145:classification / Q000235:genetics*; D015316:Genetic Therapy; D005822:Genetic Vectors; D019073:HT29 Cells; D006801:Humans; D010190:Pancreatic Neoplasms / Q000628:therapy*; D012703:Serotyping; D014161:Transduction, Genetic