A structurally altered human reduced folate carrier with increased folic acid transport mediates a novel mechanism of antifolate resistance

A mutation at nucleotide 227 of the RFC cDNA in both CEM/MTX-LF and CEM/MTX, resulting in a lysine for glutamate substitution at amino acid residue 45 predicted to reside within the first transmembrane domain of the human RFC. Upon transfer of CEM/MTX-LF cells to folate-replete medium (2.3 microM folic acid), the more efficient folic acid uptake in CEM/MTX-LF cells resulted in a 7- and 24-fold elevated total folate pool compared with CEM and CEM/MTX cells, respectively (500 versus 69 and 21 pmol/mg of protein, respectively). This markedly elevated intracellular folate pool conferred a novel mechanism of resistance to polyglutamatable (e.g. ZD1694, DDATHF, and AG2034) and lipophilic antifolates (e.g. trimetrexate and pyrimethamine) by abolishing their polyglutamylation and circumventing target enzyme inhibition. -->
Jazyk: English
ISSN: 0021-9258
Přístupová URL adresa: https://explore.openaire.eu/search/publication?articleId=dedup_wf_001::b9703a0f735cae1c52a4609699aacbf8
https://research.vumc.nl/en/publications/1b93bc74-7514-4b86-b0dc-1a263e046acc
Rights: RESTRICTED
Přírůstkové číslo: edsair.dedup.wf.001..b9703a0f735cae1c52a4609699aacbf8
Autor: Jansen, G, Mauritz, R, Drori, S, Sprecher, H, Kathmann, I, Bunni, M, Priest, D G, Noordhuis, P, Schornagel, J H, Pinedo, H M, Peters, G J, Assaraf, Y G
Přispěvatelé: Rheumatology, CCA - Cancer biology and immunology, CCA - Imaging and biomarkers, CCA - Cancer Treatment and quality of life, AII - Inflammatory diseases, Hematology laboratory, Medical oncology, Medical oncology laboratory
Jazyk: angličtina
Rok vydání: 1998
Předmět:
Zdroj: Journal of Biological Chemistry, 273(46), 30189-98. American Society for Biochemistry and Molecular Biology Inc.
Jansen, G, Mauritz, R, Drori, S, Sprecher, H, Kathmann, I, Bunni, M, Priest, D G, Noordhuis, P, Schornagel, J H, Pinedo, H M, Peters, G J & Assaraf, Y G 1998, ' A structurally altered human reduced folate carrier with increased folic acid transport mediates a novel mechanism of antifolate resistance ', Journal of Biological Chemistry, vol. 273, no. 46, pp. 30189-98 .
ISSN: 0021-9258
Popis: CEM/MTX is a subline of human CCRF-CEM leukemia cells which displays >200-fold resistance to methotrexate (MTX) due to defective transport via the reduced folate carrier (RFC). CEM/MTX-low folate (LF) cells, derived by a gradual deprivation of folic acid from 2.3 microM to 2 nM (LF) in the cell culture medium of CEM/MTX cells, resulted in a >20-fold overexpression of a structurally altered RFC featuring; 1) a wild type Km value for MTX transport but a 31-fold and 9-fold lower Km values for folic acid and leucovorin, respectively, relative to wild type RFC; 2) a 10-fold RFC1 gene amplification along with a >20-fold increased expression of the main 3.1-kilobase RFC1 mRNA; 3) a marked stimulation of MTX transport by anions (i.e. chloride); and 4) a G --> A mutation at nucleotide 227 of the RFC cDNA in both CEM/MTX-LF and CEM/MTX, resulting in a lysine for glutamate substitution at amino acid residue 45 predicted to reside within the first transmembrane domain of the human RFC. Upon transfer of CEM/MTX-LF cells to folate-replete medium (2.3 microM folic acid), the more efficient folic acid uptake in CEM/MTX-LF cells resulted in a 7- and 24-fold elevated total folate pool compared with CEM and CEM/MTX cells, respectively (500 versus 69 and 21 pmol/mg of protein, respectively). This markedly elevated intracellular folate pool conferred a novel mechanism of resistance to polyglutamatable (e.g. ZD1694, DDATHF, and AG2034) and lipophilic antifolates (e.g. trimetrexate and pyrimethamine) by abolishing their polyglutamylation and circumventing target enzyme inhibition.
Databáze: OpenAIRE
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