DNA-liposome complexes transduction of herpes simplex virus thymidine kinase renders human tongue cancer cell line sensitive to ganciclovir in vitro.
OBJECTIVE
To evaluate, in vitro, the cytotoxicity of the herpes simplex virus thymidine kinase (HSV1-tk) gene and ganciclovir (GCV) treatment, a widely used prodrug/suicide gene therapy, in human tongue cancer cell line Tbp-TL.


METHODS
Retrovirus expressing plasmid-liposome complex transduction was used. After treatment with G418 for 3 weeks, the integrated HSV1-tk gene was detected by PCR test with the primers specifically designed for HSV1-tk cDNA; HSV1-tk mRNA was detected with in situ hybridization method. In vitro cytotoxicity effect of HSV-GCV on Tbp-TL was detected with MTT and trypan blue exclusion test.


RESULTS
In vitro experiments demonstrated dose- and time-dependent cell death by transduction of the HSV1-tk gene followed by GCV treatment. The IC50 (the concentration required to elicit 50% growth inhibition) shifted from 1000 micrograms/mL in non-transduced Tbp-TL cells to 1.1 micrograms/mL in Tbp-TL/TK cells transduced with HSV1-tk gene, with the therapeutic index of 1000. Treatment with GCV at a dose of 10 micrograms/mL for 5 days led to complete cell death in HSV1-tk transduced tumor cells. When mixed with tk positive cells, the non-transduced cells (both the parent Tbp-TL cells as well as another non-transduced cell, the human muco-epidermoid carcinoma cell line M3SP2) were also killed by a degree associated with the percentage of tk positive cells. Seventy to 90% of the mixed cells were killed with only 10% to 20% tk positive cells involved.


CONCLUSIONS
These results suggest that the HSV-tk/GCV approach to human tongue cancer cell line may be efficacious, with a wide therapeutic range, and that it exerts a bystander effect in vitro.
Wang
J H
JH
Department of Oral Biology, College of Stomatology, Fourth Military Medical University (FMMU), No. 1 Kang Fu Road, Xi'an 710032, P. R. China.
Situ
Z Q
ZQ
Wu
J Z
JZ
Liu
B
B
D000970:Antineoplastic Agents / Q000627:therapeutic use*; D000998:Antiviral Agents / Q000627:therapeutic use*; D018277:Carcinoma, Mucoepidermoid / Q000188:drug therapy; D016923:Cell Death / Q000235:genetics; D004396:Coloring Agents; D004279:DNA, Viral / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D015774:Ganciclovir / Q000627:therapeutic use*; D015316:Genetic Therapy; D006801:Humans; D017403:In Situ Hybridization; D008081:Liposomes; D016133:Polymerase Chain Reaction; D011355:Prodrugs / Q000627:therapeutic use; D018139:Simplexvirus / Q000201:enzymology / Q000235:genetics*; D013778:Tetrazolium Salts; D013844:Thiazoles; D013937:Thymidine Kinase / Q000235:genetics*; D013997:Time Factors; D014062:Tongue Neoplasms / Q000188:drug therapy*; D014161:Transduction, Genetic; D014343:Trypan Blue; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D000998:Antiviral Agents; D004396:Coloring Agents; D004279:DNA, Viral; D008081:Liposomes; D011355:Prodrugs; D013778:Tetrazolium Salts; D013844:Thiazoles; D013937:Thymidine Kinase; C022616:thiazolyl blue; D014343:Trypan Blue; D015774:Ganciclovir