Adeno-associated virus-mediated gene transfer of a secreted form of TRAIL inhibits tumor growth and occurrence in an experimental tumor model.
BACKGROUND
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces cell death in various tumor cells, but relatively spares normal cells. Recombinant adeno-associated virus (rAAV) vectors have a number of advantages including in vivo long-term gene expression. Here, we assessed the biological activity of a novel, secreted form of TRAIL (sTRAIL) for cancer gene therapy using a rAAV2 vector.


METHODS
A plasmid and rAAV2 vectors were constructed encoding sTRAIL composed of a leader sequence, the isoleucine zipper, and the active domain of TRAIL (aa 95-281). The functionality of sTRAIL was validated by cell viability, FACS analysis, caspase-3 activity, and TUNEL staining. rAAV-sTRAIL was injected intratumorally to nude mice bearing human A549 lung tumor cells. Nude mice received A549 tumor cells after intravenous delivery of rAAV-sTRAIL. The antitumor effect was then evaluated by measuring tumor regression and occurrence in the experimental animal.


RESULTS
sTRAIL was released from cells transfected with the sTRAIL expression construct or transduced with rAAV-sTRAIL, and induced apoptosis in cancer cells, but spared normal fibroblast cells. Secreted sTRAIL formed oligomers including trimers with intersubunit disulfide. Purified sTRAIL exerted much lower cytotoxicity on primary human hepatocytes compared to recombinant TRAIL. Intratumoral delivery of rAAV-sTRAIL significantly inhibited growth of A549 tumors established in nude mice. A number of apoptotic tumor cells were detected by TUNEL staining in mice treated with rAAV-sTRAIL. Systemic pretreatment with rAAV-sTRAIL significantly inhibited tumor formation in nude mice.


CONCLUSIONS
The results suggest that rAAV-sTRAIL may be useful for local or systemic cancer gene therapy for treating TRAIL-sensitive tumors.
Yoo
Jinsang
J
Gene Therapy Research Unit, Korea Research Institute of Bioscience and Biotechnology, Yusong, Daejeon, Republic of Korea.
Choi
Seeyoung
S
Hwang
Kyung-Sun
KS
Cho
Won-Kyung
WK
Jung
Cho-Rok
CR
Kwon
Suk-Tae
ST
Im
Dong-Soo
DS
D000818:Animals; D051017:Apoptosis Regulatory Proteins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D003553:Cystine / Q000378:metabolism; D000229:Dependovirus; D005260:Female; D015316:Genetic Therapy; D005822:Genetic Vectors; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D008175:Lung Neoplasms / Q000517:prevention & control / Q000628:therapy*; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; D008562:Membrane Glycoproteins; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; C505654:Tnfsf10 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D003553:Cystine