Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: DrugBank:EXPT01586 (G418)
 2,237 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transformed rat thyroid cells fail to express thyroglobulin. Cells transformed with a Kirsten murine sarcoma virus carrying a temperature-sensitive ras allele lose their transformation phenotype when shifted to the nonpermissive (39 degrees C) temperature. The thyroglobulin promoter, however, remains inactive. Similarly, transfection of these cells with a thyroglobulin promoter fused to a neomycin resistance reporter gene does not produce clones resistant to G418. Treatment of the transfected cells with the DNA demethylating agent 5-azacytidine reactivates the thyroglobulin promoter and yields stable G418-resistant clones. We show that thyroglobulin promoter activity is correlated with the presence of a thyroid-specific nuclear factor, TgTF1. TgTF1 cannot be detected in transformed cells but reappears after treatment with 5-azacytidine at 39 degrees C. Restoration of Ras activity at 33 degrees C leads to the rapid loss of TgTF1 and G418 resistance.
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PMID:Reactivation of thyroglobulin gene expression in transformed thyroid cells by 5-azacytidine. 247 39

We describe studies in a canine model aimed at establishing methods for ex vivo gene delivery to thyroid follicular cells. Canine follicular cells were harvested from tissue obtained by unilateral lobectomy, grown in thyrotropin-containing media, and transduced with amphotropic retroviral vectors carrying Escherichia coli beta-galactosidase or Tn7 neomycin-resistance genes. Up to 30% of cells were transduced with retroviral vectors containing the neomycin resistance gene, and transduced cells could be selected with G418. Significantly, transduced and selected cells exhibited the morphology of thyroid follicular cells and continued to express thyroglobulin. To assess the viability of cultivated and transduced cells for transplantation, cells were stained with the vital fluorescent dye DiI, recovered by trypsinization, and transplanted into the contralateral thyroid lobe of autologous animals. Engraftment was demonstrated by fluorescence microscopy and identification of proviral sequences 7-10 days after transplantation. Proviral transcripts were evident using coupled reverse transcription and the polymerase chain reaction using total RNA from transplanted glands. Thyroid follicular cells may represent an attractive target for gene therapy due to their proliferative potential, their large protein synthetic and secretory capacity, and their susceptibility to regulation. The thyroid might be a target for therapy of congenital or acquired thyroid diseases as well as disorders requiring regulated expression of proteins in the circulation. This work demonstrates the feasibility of ex vivo gene delivery to thyroid follicular cells that may be used in future investigations.
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PMID:Retrovirus-mediated gene transfer into canine thyroid using an ex vivo strategy. 849 26

To investigate the role of ras mutations in thyroid epithelial tumorigenesis, we introduced wild-type or mutant v- or c-Ha-ras genes into a sub-cloned rat thyroid follicular epithelial cell line using retroviral vectors and a neutral selection method (G418 resistance). Mutant, but not wild-type, ras induced a spectrum of clonal phenotypes. Interestingly, many clones showed an unchanged phenotype despite ras expression at levels greater than that of the endogenous gene. Further increase in ras expression was associated with altered morphology, loss of thyroid-specific differentiation (thyroglobulin synthesis) and growth factor independence, but not. anchorage-independence or tumorigenicity. The mutation site (codon 12 or 61) did not have a significant influence. The results clearly emphasize the critical importance of expression level in determining the phenotypic effect of mutant ras on epithelial cells.
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PMID:Multiple phenotypes induced by mutant ha-ras in thyroid epithelial-cells - correlation with level of expression. 2158 14