951. Antitumor Activity of AAV-2 Vector Encoding Modified TRAIL Gene

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in a variety of cancer cell lines, but is relatively nontoxic to normal cells. Adeno-associated virus (AAV) vectors have a number of advantages including the potential sustained expression of transgenes. Here, we investigated potential usefulness of the TRAIL gene for systemic cancer therapy using AAV-2 vector. We constructed a plasmid encoding modified human TRAIL protein composed of signal peptide, an isoleucine zipper sequence, and active domain of TRAIL (pTR-PLF-ITRAD), which allows the TRAIL gene product to be released from the cells. TRAIL-sensitive cells were killed by transfection with pTR-PLF-ITRAD or a plasmid encoding full-length TRAIL (pTR-TRAIL), indicating that the plasmids produce bioactive TRAIL proteins. The culture media from TRAIL-resistant cells transfected with pTR-PLF-ITRAD, but not pTR-TRAIL induce apoptosis in a number of cancer cell lines, indicating that the modified TRAIL gene product, but not full-length TRAIL is released into the culture media. AAV-2 vector producing the modified TRAIL protein (AAV-2/PLF-ITRAD) inhibited tumor growth in A549 lung tumor-bearing nude mice. Our results suggest that AAV-2/PLF-ITRAD may be useful for systemic cancer gene therapy, provided that TRAIL is not toxic to normal cells.