Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0035412 (rhabdomyosarcoma)
 6,156 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

CPT-11 [7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin ] is a prodrug that is converted to the active metabolite SN-38 by carboxylesterases. In its active form, the drug inhibits topoisomerase I, causes DNA damage, and induces apoptosis. Data in this study show metabolism of CPT-11 to SN-38 (7-ethyl-10-hydroxycamptothecin) by a rabbit liver carboxylesterase in vitro and growth-inhibitory activity of the products of the reaction. Additionally, stable expression of the cDNA encoding this protein in Rh30 human rhabdomyosarcoma cells increased the sensitivity of the cells to CPT-11 8.1-fold. We propose that this prodrug/enzyme combination can be exploited therapeutically in a manner analogous to approaches currently under investigation with the combinations of ganciclovir/herpes simplex virus thymidine kinase and 5-fluorocytosine/cytosine deaminase.
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PMID:Overexpression of a rabbit liver carboxylesterase sensitizes human tumor cells to CPT-11. 942 50

Carboxylesterases are a ubiquitous class of enzymes thought to be involved in xenobiotic metabolism and detoxification. Primary amino acid sequence data suggest that these proteins localize to the endoplasmic reticulum. However, since this family of proteins is highly homologous, the generation of specific reagents to monitor expression and subcellular localization has been unsuccessful. To accomplish in situ detection of a human alveolar macrophage carboxylesterase and a rabbit liver carboxylesterase, we constructed plasmids that expressed recombinant proteins containing an 11 amino acid influenza hemagglutinin tag near the C-terminus. These proteins retained carboxylesterase activity as determined by the conversion of o-nitrophenol acetate to o-nitrophenol. Following transfection of plasmids encoding these proteins into mammalian cells, cells were analyzed by both fluorescence and electron microscopy. The tagged enzymes were localized to the endoplasmic reticulum of both Cos7 monkey kidney cells and Rh30 human rhabdomyosarcoma cells. No tagged protein was detectable in the culture media. Hence, epitope tagging allowed the analysis of expression and localization of specific carboxylesterases. The methods described in this paper are, therefore, applicable to any protein, including those that are highly homologous to other candidate molecules.
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PMID:In situ subcellular localization of epitope-tagged human and rabbit carboxylesterases. 966 12

Overexpression of specific transcription factors by tumor cells can be exploited to regulate expression of proteins that induce apoptosis or activate prodrugs, thereby producing tumor-selective toxicity. A majority of advanced-stage neuroblastomas overexpress the transcription factor N-MYC, and this overexpression is associated with poor prognosis. This study describes regulation of expression by N-MYC, via the ornithine decarboxylase (ODC) promoter, of a rabbit liver carboxylesterase (CE) that activates the prodrug CPT-11. Chloramphenicol acetyltransferase reporter assays and CE activity assays in transiently transfected neuroblastoma cell lines (SJNB-1, SJNB-4, NB-1691) and rhabdomyosarcoma cell lines (JR1neo20, JR1Nmyc6, JR1Nmyc9) support this approach as a potential method for sensitizing tumor cells to CPT-11. Clonogenic assays with IMR32 human neuroblastoma cells which express N-MYC and that had been stably transfected with a plasmid containing an ODC promoter/CE cassette corroborated results of enzyme activity assays. Specifically, IMR32.ODC.CE cells expressed approximately eightfold more CE activity than IMR32.CMV.neo cells; and 5 microM CPT-11 reduced the clonogenic potential of IMR32.ODC.CE cells to zero, while 50 microM CPT-11 was required to produce the same effect with IMR32.CMV.neo cells. Current experiments focus on adenoviral delivery of an ODC promoter/CE cDNA cassette for potential virus-directed enzyme prodrug therapy applications.
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PMID:Use of the ornithine decarboxylase promoter to achieve N-MYC-mediated overexpression of a rabbit carboxylesterase to sensitize neuroblastoma cells to CPT-11. 1093 67