Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.1.21 (thymidine kinase)
 7,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

From previously constructed genomic libraries of a Taiwan WSSV isolate, a putative WSSV tk-tmk gene was identified. Uniquely, the open reading frame (ORF) of this gene was predicted to encode a novel chimeric protein of 388 amino acids with significant homology to two proteins: thymidine kinase (TK) and thymidylate kinase (TMK). Northern blot analysis with a WSSV tk-tmk-specific riboprobe detected a major transcript of 1.6 kb. When healthy adult Penaeus monodon shrimp were inoculated with WSSV, the tk-tmk gene transcript was first detected by RT-PCR analysis at 4 h postinfection and transcription levels continued to increase over the first 18 h. The gene's major in vitro transcription and translation product, equivalent to the predicted size (43 kDa), is a single chimeric protein that includes both the TK and TMK functional motifs. Evidence for phylogenetic analysis and sequence alignment suggested that the gene may have resulted from the fusion of a cellular-type TK gene and a cellular-type TMK gene. Its unique arrangement may also provide a valuable gene marker for WSSV.
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PMID:Identification and characterization of a shrimp white spot syndrome virus (WSSV) gene that encodes a novel chimeric polypeptide of cellular-type thymidine kinase and thymidylate kinase. 1106 40

Herpes simplex virus thymidine kinase (HSVTK) with the guanosine analog ganciclovir (GCV) is currently the most widely used suicide gene/prodrug system for gene therapy of cancer. Despite the broad application of the HSVTK/GCV approach, phosphorylation of GCV to its active state is inefficient such that high, myelosuppressive doses of GCV are needed to observe an antitumor effect. One strategy used to overcome the poor substrate specificity of HSVTK towards GCV (Km = 45 microM) has been to create novel forms of TK with altered substrate preferences. Such mutant TKs have shown benefit and are currently in clinical use. We describe here a second strategy to increase the amount of intracellular triphosphorylated GCV by involving the second enzyme in the GCV activation pathway, guanylate kinase (GMK). As a means to overcome the bottleneck of prodrug activation from the monophosphate to the diphosphate, we sought to combine both the critical HSVTK and GMK activities together. In this report we describe the construction of a fusion or chimeric protein of HSVTK and guanylate kinase, show data that demonstrate it confers a approximately 175-fold decrease in IC50 compared to HSVTK alone in response to ganciclovir treatment in stably transfected C6 glioma cells and finally, we present biochemical evidence of a kinetic basis for this improved cell killing.
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PMID:A guanylate kinase/HSV-1 thymidine kinase fusion protein enhances prodrug-mediated cell killing. 1681 Jan 97

Oncolytic virotherapy is a promising therapeutic approach for the treatment of cancer. TG6002 is a recombinant oncolytic vaccinia virus deleted in the thymidine kinase and ribonucleotide reductase genes and armed with the suicide gene FCU1, which encodes a bifunctional chimeric protein that efficiently catalyzes the direct conversion of the nontoxic 5-fluorocytosine into the toxic metabolite 5-fluorouracil. In translational research, canine tumors and especially mammary cancers are relevant surrogates for human cancers and can be used as preclinical models. Here, we report that TG6002 is able to replicate in canine tumor cell lines and is oncolytic in such cells cultured in 2D or 3D as well as canine mammary tumor explants. Furthermore, intratumoral injections of TG6002 lead to inhibition of the proliferation of canine tumor cells grafted into mice. 5-fluorocytosine treatment of mice significantly improves the anti-tumoral activity of TG6002 infection, a finding that can be correlated with its conversion into 5-fluorouracil within infected fresh canine tumor biopsies. In conclusion, our study suggests that TG6002 associated with 5-fluorocytosine is a promising therapy for human and canine cancers.
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PMID:Preclinical Evaluation of the Oncolytic Vaccinia Virus TG6002 by Translational Research on Canine Breast Cancer. 3307 63


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