Increased thymidylate synthetase in 5-fluorodeoxyuridine resistant cultured hepatoma cells

Priest, David G.; Ledford, Barry E.; Doig, M.T.

doi:10.1016/0006-2952(80)90607-3

Cited by 45 publications

(8 citation statements)

References 13 publications

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“…Resistance to FUdR in mammalian cells has been documented to be associated with decreased drug uptake (Sobrero et al 1985), decreased levels of TK (Umeda and Heidelberger 1968;Mulkins and Heidelberger 1982), or increases in levels of TS (Baskin et al 1975;Priest and Ledford 1980). In plant cell variants isolated from cell cultures of soybean (Ohyama 1974) and carrot (Lazar et al 1989), resistance to FUdR was found to be due to the greatly elevated levels of TS.…”

Section: Discussionmentioning

confidence: 94%

Biochemical and genetic characterization of 5-fluoro-2?-deoxyuridine-resistant mutants of Arabidopsis thaliana

King

1994

Planta

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Abstract. Two independently isolated 5-fluoro-2'-deoxyuridine (FUdR)-resistant mutant lines of Arabidopsis thaliana (L.) Heynh., FUD-1 and FUD-2, were identified by screening M2 populations of ethylmethane-sulfonatemutagenized seeds. The resistance was found to be due to single, recessive, nuclear gene mutations. Genetic complementation tests indicated that these two mutations were in the same gene locus, which was designated furl, and mapped to linkage group four of Arabidopsis. Enzyme assays indicated that the mutants were not defective in thymidine-kinase activity. Greatly reduced concentrations of intracellular 3H were detected in furl/furl plants compared with the wild type after incubation of wild-type and resistant plants in a medium with [3H]FUdR, indicating that either reduced uptake of FUdR or enhanced efflux of FUdR metabolites was the major reason for FUdR-resistance. furl/furl plants also had significantly decreased uptake of thymidine and uridine compared with the wild type but no difference was found in the uptake of adenosine, guanosine, thymine, uracil or amino acids. It is suggested that the transport system affected in the furl/furl mutants is one specific to pyrimidine nucleosides.

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Section: Discussionmentioning

confidence: 94%

Biochemical and genetic characterization of 5-fluoro-2?-deoxyuridine-resistant mutants of Arabidopsis thaliana

King

1994

Planta

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“…The observation that the overproduction trait is unstable in the absence of selective pressure is consistent with the possibility that the amplified genes, if present, are located on double minute chromosomes (15 Other laboratories have also reported the isolation of FdUrd-resistant mammalian cell lines that overproduce TS. However, the level of overproduction has, to our knowledge, never exceeded 10-fold (3,5,23,34). The higher level of overproduction obtained in our selection procedure might be due to differences in the cell lines being selected or to differences in the selection procedure (for example, the inclusion of uridine and cytidine in the selection medium or the elimination of TK-cells by HAT selection).…”

Section: Mol Cell Biolmentioning

confidence: 92%

Thymidylate synthetase overproduction in 5-fluorodeoxyuridine-resistant mouse fibroblasts.

Rossana¹,

Rao²,

Johnson³

1982

Mol. Cell. Biol.

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We describe the isolation and characterization of a series of 5-fluorodeoxyuridine (FdUrd)-resistant mouse 3T6 cell lines that overproduce thymidylate synthetase (TS) by up to 50-fold compared with the parental cells. The resistant cells were selected by growing 3T6 cells or a methotrexate-resistant 3T6 cell line (M50L3, isolated previously in our laboratory) in gradua$ increasing concentrations of FdUrd. Uridine and cytidine were included in the culture medium to reduce toxicity from metabolic products of FdUrd. Cells that were resistant to the drug by virtue of loss of thymidine kinase activity were eliminated by selection in medium containing hypoxanthine, methotrexate, and thymidine. M5OL3 cells were found to adapt to FdUrd more readily than 3T6 cells. A number of clones were isolated that were able to grow in the presence of 3 ,uM (M50L3 derived) or 0.3 ,uM (3T6 derived) FdUrd. Several were found to overproduce TS by 10 to 50-fold compared with normal 3T6 cells. All were found to have thymidine kinase activity, although the enzyme level was significantly reduced in some clones. The overproduced TS was inactivated by 5-fluorodeoxyuridylic acid at the same concentration as the enzyme from 3T6 cells. TS was purified from the LU3-7 clone (50-fold overproducer) by affinity chromatography on methotrexate-polyacrylamide. The monomer molecular weight was about 38,000, which was the same as the molecular weight of the monomer in 3T6 cells. The overproduction trait was gradually lost (half-life, 3 weeks) when LU3-7 cells were grown in the absence of FdUrd. The overproducing cells will provide an abundant supply of TS and (very likely) its mRNA and may serve as a convenient model system for detailed studies of the regulation of TS gene expression during the cell cycle.

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“…Gene amplification leading to increased TS expression as a mechanism of experimental resistance to pyrimidine-based (FdUrd) (Baskin et al, 1975;Priest et al, 1980;Rossana et al, 1982;Berger et al, 1985;Jenh et al, 1985) or folatebased TS inhibitors has been previously reported Iman et al, 1987;Danenberg and Danenberg, 1989;O'Connor et al, 1992). There is also evidence that this can occur in man in response to treatment with 5-FU (Clark et al, 1987).…”

Section: Cross-resistance Studiesmentioning

confidence: 99%

Mechanisms of acquired resistance to the quinazoline thymidylate synthase inhibitor ZD1694 (Tomudex) in one mouse and three human cell lines

Kèlland²,

Kimbell³

et al. 1995

Br J Cancer

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Increased thymidylate synthetase in 5-fluorodeoxyuridine resistant cultured hepatoma cells

Cited by 45 publications

References 13 publications

Biochemical and genetic characterization of 5-fluoro-2?-deoxyuridine-resistant mutants of Arabidopsis thaliana

Biochemical and genetic characterization of 5-fluoro-2?-deoxyuridine-resistant mutants of Arabidopsis thaliana

Thymidylate synthetase overproduction in 5-fluorodeoxyuridine-resistant mouse fibroblasts.

Mechanisms of acquired resistance to the quinazoline thymidylate synthase inhibitor ZD1694 (Tomudex) in one mouse and three human cell lines

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