Transduction of a drug-sensitive toxic gene into human leukemia cell lines with a novel retroviral vector.
To investigate the possibility of killing tumor cells by the expression of an exogenously introduced toxic gene, we have constructed a novel retroviral vector (LTRNL) which has the polyA signal deleted herpes simplex virus type 1 thymidine kinase (HSV1-tk) gene. The vector becomes toxic by treating cells expressing HSV1-tk with the antiherpetic drugs acyclovir or ganciclovir (GCV). Cells of the human leukemia lines (K562, MEG-01) were infected with this vector and two transduced cell lines (K562/LTRNL, MEG-01/LTRNL) were established. Southern blot analysis confirmed the integration of the HSV1-tk transgene in these cells and Northern blot analysis exhibited the expression of 4.8-kb viral mRNA containing the HSV1-tk gene. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay for the in vitro cytotoxic effects of GCV to these cells demonstrated that concentrations of about 2.5 microM for K562/LTRNL and 1.25 microM for MEG-01/LTRNL cells resulted in 50% inhibition of cell growth after 72 hr. Subcutaneous tumors of MEG-01/LTRNL in KSN nude mice, but not those of uninfected MEG-01 cells, showed durable regressions after exposure of the mice to 40 mg/kg of GCV given subcutaneously once a day for 15 days. This study indicates that the LTRNL-infected human leukemia cells exhibit inducible susceptibility to GCV.
Abe
A
A
First Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Takeo
T
T
Emi
N
N
Tanimoto
M
M
Ueda
R
R
Yee
J K
JK
Friedmann
T
T
Saito
H
H
D000212:Acyclovir / Q000494:pharmacology; D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D002470:Cell Survival / Q000187:drug effects; D015774:Ganciclovir / Q000494:pharmacology; D015870:Gene Expression; D005822:Genetic Vectors; D006801:Humans; D007938:Leukemia / Q000235:genetics* / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D016297:Mutagenesis, Site-Directed; D011061:Poly A; D021382:Protein Sorting Signals / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012367:RNA, Viral / Q000235:genetics; D018139:Simplexvirus / Q000201:enzymology / Q000235:genetics*; D013937:Thymidine Kinase / Q000235:genetics*; D014162:Transfection; D014407:Tumor Cells, Cultured
D021382:Protein Sorting Signals; D012333:RNA, Messenger; D012367:RNA, Viral; D011061:Poly A; D013937:Thymidine Kinase; D015774:Ganciclovir; D000212:Acyclovir