title: Noninvasive imaging of enhanced prostate-specific gene expression using a two-step transcriptional amplification-based lentivirus vector.
abstract: Noninvasive evaluation of gene transfer to specific cells or tissues will allow for long-term, repetitive monitoring of transgene expression. Tissue-specific promoters that restrict the expression of a transgene to tumor cells play a vital role in cancer gene therapy imaging. In this study, we have developed a third-generation HIV-1-based lentivirus vector carrying a prostate-specific promoter to monitor the long-term, sustained expression of the firefly luciferase (fl) reporter gene in living mice. The fl gene in the transcriptionally targeted vector is driven by an enhanced prostate-specific antigen promoter in a two-step transcriptional amplification (TSTA) system. The efficiency of the lentivirus (LV-TSTA)-mediated gene delivery, cell-type specificity, and persistence of gene expression were evaluated in cell culture and in living mice carrying prostate tumor xenografts. In vivo bioluminescence imaging with a cooled charge-coupled device camera revealed significantly high levels of fl expression in prostate tumors. Injection of LV-TSTA directly into the prostate of male nude mice revealed efficient and long-term fl gene expression in the prostate tissue for up to 3 months. These studies demonstrate the significant potential of TSTA-based lentivirus vectors to confer high levels of tissue-specific gene expression from a weak promoter, while preserving cell-type specificity and the ability to image noninvasively the sustained, long-term expression of reporter genes in living animals.
authors.affiliation: The Crump Institute for Molecular Imaging, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA.
authors.forename: Meera
authors.initials: M
authors.lastname: Iyer
authors.forename: Felix B
authors.initials: FB
authors.lastname: Salazar
authors.forename: Xiaoman
authors.initials: X
authors.lastname: Lewis
authors.forename: Liqun
authors.initials: L
authors.lastname: Zhang
authors.forename: Michael
authors.initials: M
authors.lastname: Carey
authors.forename: Lily
authors.initials: L
authors.lastname: Wu
authors.forename: Sanjiv S
authors.initials: SS
authors.lastname: Gambhir
mesh_terms: D000818:Animals; D018014:Gene Transfer Techniques; D017930:Genes, Reporter; D015316:Genetic Therapy; D005822:Genetic Vectors; D016325:HIV Long Terminal Repeat / Q000235:genetics; D015497:HIV-1 / Q000235:genetics*; D006801:Humans; D049409:Luciferases, Firefly / Q000235:genetics / Q000378:metabolism; D008163:Luminescent Measurements; D008297:Male; D051379:Mice; D008819:Mice, Nude; D011401:Promoter Regions, Genetic; D017430:Prostate-Specific Antigen / Q000096:biosynthesis / Q000235:genetics*; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000628:therapy*; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
chemical_list: D049409:Luciferases, Firefly; D017430:Prostate-Specific Antigen