A tandemly repeated thyroglobulin core promoter has potential to enhance efficacy for tissue-specific gene therapy for thyroid carcinomas.
Recombinant adenoviruses, carrying herpes simplex virus thymidine kinase (HSVtk) genes, were developed to evaluate the possibility of tissue-specific gene therapy for thyroid carcinomas. The HSVtk gene was driven by a minimal thyroglobulin (TG) promoter (AdTGtk) and a tandemly repeated minimal TG promoter (Ad2 x TGtk) to obtain thyroid-specific cell killing ability. The transduction of HSVtk genes by infection with Ad2 x TGtk followed by ganciclovir (GCV) treatment showed more powerful cytotoxicity for TG-producing FRTL5 cells, a rat normal thyroid cell line, and FTC-133 cells, a human follicular thyroid carcinoma cell line, than when infected with AdTGtk in vitro. The cell killing ability of Ad2 x TGtk was 10- to 30-fold higher than that of AdTGtk and similar to that of AdCMVtk, which carries HSVtk under the control of CMV promoter. Whereas after treatment with adenovirus/GCV to non-TG-producing cell lines (undifferentiated thyroid carcinoma cell lines and carcinoma cell lines from other tissues), Ad2 x TGtk and AdTGtk needed more than 100-fold concentrated GCV to reach IC(50) compared to AdCMVtk. We confirmed the enhanced efficacy of Ad2 x TGtk for tissue-specific cytotoxicity in vivo. After adenovirus/GCV treatment for FTC-133 tumor-bearing nude mice, Ad2 x TGtk enhanced tumor growth inhibition and survival rates compared to AdTGtk. Tumor growth inhibition and survival rates by Ad2 x TGtk were similar to that by AdCMVtk. Moreover, any toxic effect for rat normal tissues was not revealed after intravenous injections with Ad2 x TGtk and intraperitoneal administrations with GCV in vivo, whereas severe liver damages were observed after treatment with AdCMVtk/GCV. These data indicate a beneficial effect of Ad2 x TGtk for tissue-specific gene therapy for TG-producing thyroid carcinomas without toxicity for normal tissues.
Takeda
Teiji
T
Department of Aging Medicine and Geriatrics, Shinshu University, School of Medicine, Matsumoto, Nagano, Japan. teiji@hsp.md.shinshu-u.ac.jp
Yamazaki
Masanori
M
Minemura
Kesami
K
Imai
Yosuke
Y
Inaba
Hidehumi
H
Suzuki
Satoru
S
Miyamoto
Takahide
T
Ichikawa
Kazuo
K
Kakizawa
Tomoko
T
Mori
Jun-Ichirou
J
DeGroot
Leslie J
LJ
Hashizume
Kiyoshi
K
D000256:Adenoviridae / Q000235:genetics*; D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D000998:Antiviral Agents / Q000627:therapeutic use; D001219:Aspartate Aminotransferases / Q000097:blood; D002455:Cell Division; D015774:Ganciclovir / Q000627:therapeutic use; D017930:Genes, Reporter; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D000882:Haplorhini; D006801:Humans; D066298:In Vitro Techniques; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D011401:Promoter Regions, Genetic; D051381:Rats; D018139:Simplexvirus / Q000201:enzymology*; D020080:Tandem Repeat Sequences / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics / Q000494:pharmacology; D013954:Thyroglobulin / Q000235:genetics*; D013964:Thyroid Neoplasms / Q000201:enzymology / Q000473:pathology / Q000628:therapy*; D001616:beta-Galactosidase / Q000378:metabolism
D000998:Antiviral Agents; D013954:Thyroglobulin; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D013937:Thymidine Kinase; D001616:beta-Galactosidase; D015774:Ganciclovir