Vaccinia as a vector for tumor-directed gene therapy: biodistribution of a thymidine kinase-deleted mutant.
Tumor-directed gene therapy, such as "suicide gene" therapy, requires high levels of gene expression in a high percentage of tumor cells in vivo to be effective. Current vector strategies have been ineffective in achieving these goals. This report introduces the attenuated (thymidine kinase (TK)-negative) replication-competent vaccinia virus (VV) as a potential vector for tumor-directed gene therapy by studying the biodistribution of VV in animal tumor models. A TK-deleted recombinant VV (Western Reserve strain) expressing luciferase on a synthetic promoter was constructed. Luciferase activity was measured in vitro after transduction of a variety of human and murine tumor cell lines and in vivo after intraperitoneal (i.p.) delivery in C57BL/6 mice with 7-day i.p. tumors (10(6) MC-38 cells). Three other in vivo tumor models were examined for tumor-specific gene expression after intravenous delivery of VV (human melanoma in nude mice, adenocarcinoma liver metastasis in immunocompetent mice, and subcutaneous sarcoma in the rat). In addition, a replication-incompetent vaccinia (1 microg of psoralen and ultraviolet light, 365 nm, 4 minutes) was tested in vitro and in vivo and compared with active virus. Luciferase activity in i.p. tumors at 4 days after i.p. injection of VV was >7000-fold higher than lung, >3000-fold higher than liver, and >250-fold higher than ovary. In addition, intravenous injection of VV resulted in markedly higher tumor luciferase activity compared with any other organ in every model tested (up to 188,000-fold higher than liver and 77,000-fold higher than lung). Inactivation of the virus resulted in negligible gene expression in vivo. In summary, VV has a high transduction efficiency in tumor cells with high levels of gene expression. The results suggest a selective in vivo replication of TK-deleted VV in tumor cells. Replication competent, TK-deleted VV appears to be an ideal vector for testing the in vivo delivery of toxic genes to tumor cells.
Puhlmann
M
M
Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Brown
C K
CK
Gnant
M
M
Huang
J
J
Libutti
S K
SK
Alexander
H R
HR
Bartlett
D L
DL
D000818:Animals; D014408:Biomarkers, Tumor; D004195:Disease Models, Animal; D005363:Ficusin / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects / Q000528:radiation effects; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics*; D019073:HT29 Cells; D006801:Humans; D008156:Luciferases / Q000096:biosynthesis; D051379:Mice; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D009154:Mutation; D009374:Neoplasms, Experimental / Q000235:genetics / Q000378:metabolism / Q000628:therapy*; D017319:Photosensitizing Agents / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D013937:Thymidine Kinase / Q000235:genetics* / Q000378:metabolism; D014162:Transfection / Q000187:drug effects / Q000528:radiation effects; D014407:Tumor Cells, Cultured; D014466:Ultraviolet Rays; D014616:Vaccinia virus / Q000235:genetics*; D014779:Virus Replication
D014408:Biomarkers, Tumor; D017319:Photosensitizing Agents; D008156:Luciferases; D013937:Thymidine Kinase; D005363:Ficusin