Objective: To investigate the expression of the soluble tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) mediated by adeno-associated virus (AAV) and its tumoricidal activity in vitro and vivo.
Methods: The recombinant AAV expression vector encoding the extracellular domain (114-281aa peptide, TRAIL(114-281)) of TRAIL was constructed and transfected into human embryotic kidney cells HEK293 for virus package. The human tumor cell lines of T lymphocyte leukemia Jurkat, liver cancer HepG2 and SMMC-7721, and cervical cancer HeLa were transduced by using the recombinant virus particles respectively. The recombinant virus particles were also injected into C57BL/6 mice via the hepatic portal vein or hypodermic, intramuscular, celiac and oral pathways to study the expression of TRAIL(114-281). The recombinant virus titer was determined by real-time PCR. The expression of TRAIL(114-281) was evaluated by ELISA, Western blotting and immunohistochemistry assay respectively. The tumoricidal activity and apoptosis were evaluated by MTT assay.
Results: The recombinant AAV encoding for the soluble TRAIL (114 - 281aa) were constructed successfully. The titer of recombinant virus was 7.5 x 10(12) genome particles (Gps)/ml. Transduction of rAAV-TRAIL(114-281) led to high level expression of TRAIL(114-281) and the induction of apoptosis of Jurkat, Hela and SMMC-7721 cancer cells, but not HepG2 cells, in vitro. The recombinant peptide TRAIL(114-281) in trimeric active form was highly and constantly expressed in the hepatocytes and secreted into the serum up to 6 months in the of C57BL/6 mice injected with the recombinant virus particles via the hepatic portal vein. The peptide TRAIL(114-281) in the livers, but not other tissues, were also detected in the mice administrated with rAAV-TRAIL(114-281) particles via subcutaneous, intramuscular, intraceliac or oral pathway.
Conclusion: The long term, stable and liver-tropism expression of peptide TRAIL(114-281) in mice mediated by rAAV-TRAIL(114-281) provides a prospective novel strategy for tumor gene therapy of numerous cancers, especially liver cancer.