A COMPARISON OF THE PROPERTIES OF DIFFERENT RETROVIRAL VECTORS CONTAINING THE MURINE TYROSINASE PROMOTER TO ACHIEVE TRANSCRIPTIONALLY TARGETED EXPRESSION OF THE HSVTK OR IL-2 GENES
R. Vile et al., A COMPARISON OF THE PROPERTIES OF DIFFERENT RETROVIRAL VECTORS CONTAINING THE MURINE TYROSINASE PROMOTER TO ACHIEVE TRANSCRIPTIONALLY TARGETED EXPRESSION OF THE HSVTK OR IL-2 GENES, Gene therapy, 1(5), 1994, pp. 307-316
To target therapeutic genes specifically to melanoma cells, we have co
nstructed recombinant retroviruses where transcriptional control of th
e murine interleukin-2 (mIL-2) or herpes simplex virus thymidine kinas
e (HSVtk) genes is provided by the 5' promoter region of the murine ty
rosinase gene. Tissue-specific expression of these genes is observed b
oth at the mRNA and protein levels in the B16 melanoma line compared w
ith NIH3T3 fibroblasts. Thus, B16 cells infected with one such retrovi
rus containing the HSVtk gene exhibited a > 90% reduction in colony-fo
rming efficiency after exposure to 1 mu g/ml ganciclovir, relative to
controls, whereas similarly infected NIH3T3 cells showed < 10% reducti
on in colony-forming efficiency under comparable conditions. The degre
e of preservation of tissue-specific expression from the internal tyro
sinase promoter depended upon the exact molecular design of the vector
, possibly as a consequence of the interference between closely juxtap
osed promoters within the provirus. Our results show that retroviral v
ectors can be prepared with the capacity to regulate expression of ins
erted genes specifically in a particular cell type and may be useful f
or developing efficient, targeted vectors for the in vivo delivery of
genetic therapies for malignant melanoma.