title: Transcriptional activation of the thyroglobulin promoter directing suicide gene expression by thyroid transcription factor-1 in thyroid cancer cells.
abstract: Gene therapy with thyroglobulin (TG) promoter and a prodrug/suicide gene combination may prove useful as a treatment for thyroid carcinoma. However, most poorly differentiated and anaplastic thyroid carcinomas have lost the ability to express the TG gene expression accompanied by loss of transcription factors [thyroid transcription factor-1 (TTF-1), TTF-2, or Pax-8] interacting with the TG promoter. In anticipation of developing transcriptionally targeted gene therapy of TG-nonproducing thyroid carcinomas, we investigated the effect of TTF-1 gene transfer on TG promoter activity and the cytotoxic effect obtained by the TG promoter-driven HSV-TK gene along with ganciclovir in thyroid carcinoma and nonthyroidal cells. Using a chimeric construct containing the 5'-flanking region of the rat TG gene between -826 and +39 bp and the luciferase gene, TG promoter activity was detected in a normal rat thyroid cell line (FRTL-5), but not in a dedifferentiated line of thyroid cells (FRT) expressing Pax-8 but not TTF-1, TTF-2, or TG [TTF-1(-)/TTF-2(-)/Pax-8(+)/TG(-)], or in a human papillary thyroid carcinoma cell line [BHP15-3; TTF-1(-)/TTF-2(-)/Pax-8(-)/TG(-)], a human pulmonary cell line [H441; TTF-1(+)/TTF-2(-)/Pax-8(-)/TG(-)], or a dog kidney epithelial cell line [MDCK; TTF-1(-)/TTF-2(-)/Pax-8(+)/TG(-)]. Cotransfection of the TTF-1 expression vector stimulated TG promoter activity in FRT and BHP15-3 dedifferentiated thyroid cells, but not in H441 pulmonary cells. Only weak activation was observed in MDCK kidney cells. We then constructed recombinant adenovirus vectors, AdTTF-1 and ADTGTK: AdTTF-1 contained cytomegalovirus promoter and rat TTF-1 cDNA; AdTGTK carried the TG promoter-driven HSV-TK gene. Infection with AdTGTK and combined with GCV treatment induced a cytotoxic effect in FRTL-5 cells but not in dedifferentiated thyroid or nonthyroid cells. Cotransduction of AdTTF-1 and AdTGTK permitted 90% cytotoxicity for BHP15-3 and >95% cytotoxicity for FRT, as well as for BHP7-13 and BHP18-21v thyroid cancer cell lines [both/TTF1(-)/TTF-2(-)/Pax-8(+)/TG(-)]. In contrast, little cytotoxicity was seen for H441 and MDCK cell lines even with 300 microg/ml of ganciclovir. These results suggest that cotransduction of a TG promoter-controlled suicide gene and the TTF-1 gene by adenoviral vectors confers transcriptionally targeted gene-mediated cytotoxicity in poorly differentiated thyroid carcinoma cells unable to express the TG gene.
authors.affiliation: Third Department of Internal Medicine, Yamanashi Medical University, Yamanashi 409-3898, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Shimura
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
authors.forename: A
authors.initials: A
authors.lastname: Miyazaki
authors.forename: F
authors.initials: F
authors.lastname: Furuya
authors.forename: K
authors.initials: K
authors.lastname: Ohta
authors.forename: K
authors.initials: K
authors.lastname: Haraguchi
authors.forename: T
authors.initials: T
authors.lastname: Endo
authors.forename: T
authors.initials: T
authors.lastname: Onaya
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002291:Carcinoma, Papillary / Q000188:drug therapy / Q000235:genetics* / Q000628:therapy; D015774:Ganciclovir / Q000493:pharmacokinetics / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D051381:Rats; D018139:Simplexvirus / Q000201:enzymology / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism; D013954:Thyroglobulin / Q000096:biosynthesis / Q000235:genetics*; D013964:Thyroid Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000628:therapy; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors / Q000235:genetics*; D015533:Transcriptional Activation; D014161:Transduction, Genetic; D014407:Tumor Cells, Cultured
chemical_list: C000614412:NKX2-1 protein, human; C000614416:Nkx2-1 protein, rat; D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D013954:Thyroglobulin; D013937:Thymidine Kinase; D015774:Ganciclovir