Liposome-mediated gene therapy using HSV-TK/ganciclovir under the control of human PSA promoter in prostate cancer cells.
To more accurately determine the tissue-specific expression of the target gene in prostate cancer cells, we introduced the enhancer element (-4,777 to -3,934; PSAR) and the promoter region (PSAP) of the prostate-specific antigen (PSA) gene. Furthermore, to elucidate the advantages of using liposomes as a gene carrier, we screened more than 20 liposome preparations in this study. The 5' upstream region of PSA gene (PSARPSAP) was conjugated to either the chloramphenicol acetyltransferase (CAT) gene or herpes simplex virus thymidine kinase (TK) gene, and the transfection of these plasmids was carried out using cationic liposomes, DMRIE-C (Gibco) or LipoTAXI (Stratagene). The expression of CAT activity was clearly observed when PSARPSAP-CAT plasmid was transfected into PSA-positive LNCaP cells, whereas no CAT activity was detected in PSA-negative DU145 cells or bladder carcinoma T24 cells. The CAT activity increased after the addition of testosterone. We then evaluated the therapeutic effect of the PSARPSAP-TK plasmid in vitro. When PSARPSAP-TK plasmid was transfected and ganciclovir was added to the medium, the growth of LNCaP cells was inhibited, while no growth inhibition was observed in DU145 cells. Furthermore, this inhibitory effect was observable even when the cells were cultured in a medium supplemented with dialyzed fetal bovine serum. These results suggest that the liposome-mediated transfection of PSARPSAP-TK appears to be a potentially effective approach for selecting the optimal treatment for tumor cells producing PSA even with the low androgen levels seen in patients treated by anti-androgen therapy.
Suzuki
S
S
Department of Urology, National Defense Medical College, 302 Namiki, Tokorozawa, Saitama 359-8513, Japan. sushi@fa2.so-net.ne.jp
Tadakuma
T
T
Kunitomi
M
M
Takayama
E
E
Sato
M
M
Asano
T
T
Nakamura
H
H
Hayakawa
M
M
D015774:Ganciclovir; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D008081:Liposomes; D008297:Male; D011401:Promoter Regions, Genetic; D017430:Prostate-Specific Antigen / Q000235:genetics*; D011471:Prostatic Neoplasms / Q000235:genetics / Q000628:therapy*; D018139:Simplexvirus; D013937:Thymidine Kinase; D014407:Tumor Cells, Cultured
D008081:Liposomes; D013937:Thymidine Kinase; D017430:Prostate-Specific Antigen; D015774:Ganciclovir