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Implication de la protéine de liaison des folates dans la résistance au méthotrexate de la lignée d'adénocarcinome colique humain, HT29

Abstract : Aim : Methotrexate (MTX) is one of the major antifolates used as antimitotic. Sorne HT29 cells (human colon tumor cellline) are resistant to MTX. At concentration higher than 1O-4M, they are differentiated in enterocyt like cells, and show important amplification of dihydrofolate reductase (DHFR). This is not the only MTX resistance mechanism found in the literature. MTX transport was investigated by the study of membrane folate binding protein (M-FBP) and reduced folate carrier (RFC). Methods : HT29 cells adapted to increased concentration in MTX were cultivated, with and without MTX, in media where folie acid concentration was between 0.9 nM à 9 IlM. We studied the transcription of M-FBPa, RFC, and DHFR genes by semi-quantitative RT-PCR semi-quantitative. Binding activity of folie acid was measured in membrane preparations and after protein solubilisation by phosphatidylinositol-phospholipase C, as weIl as in the medium. The effect of the medium on cell growth was analysed. Results: HT29 10-4M MTX cells transcripts respectively 3 and 2 times more M-FBPa than HT29 cells and HT29 10-4M MTX cells. With a lower folie acid concentration in the medium, M-FBPa gene transcription sill increases. DHFR gene transcription is 2.4 higher with HT29 10-4M MTX. RFC gene transcription is the same, whatever are the cells and the medium. Culture medium does not contain soluble folate binding protein (S-FBP). FBP binding activity is 2 to 8 times higher in HT29 10-4M MTX, compared with other HT29 cells. Conclusion : Linked with DHFR amplification, M-FBPa overexpression contributes to MTX resistance of HT29 10-4M MTX cells.
Mots-clés : Méthotrexate Folique Acide
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http://docnum.univ-lorraine.fr/prive/SCD_T_2001_0280_DE_NONANCOURT_DIDION.pdf
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https://hal.univ-lorraine.fr/tel-01746468
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Submitted on : Thursday, March 29, 2018 - 10:38:24 AM
Last modification on : Tuesday, December 15, 2020 - 1:59:44 PM

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Marie De Nonancourt-Didion. Implication de la protéine de liaison des folates dans la résistance au méthotrexate de la lignée d'adénocarcinome colique humain, HT29. Médecine humaine et pathologie. Université Henri Poincaré - Nancy 1, 2001. Français. ⟨NNT : 2001NAN11314⟩. ⟨tel-01746468⟩

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