Mechanisms of methotrexate resistance in acute leukemia: Decreased transport and polyglutamylation Journal Article
| Authors: | Gorlick, R.; Cole, P.; Banerjee, D.; Longo, G.; Li, W. W.; Hochhauser, D.; Bertino, J. R. |
| Article Title: | Mechanisms of methotrexate resistance in acute leukemia: Decreased transport and polyglutamylation |
| Abstract: | Drug resistance limits the effectiveness of methotrexate (MTX) for the treatment of acute leukemia. An increased understanding of the pathways involved in folate metabolism has allowed investigations of the mechanisms of resistance observed in leukemic blasts obtained from patients. Acute lymphocytic leukemia (ALL) was studied for mechanisms of acquired MTX resistance. MTX transport in 27 patients with untreated ALL and 31 patients with relapsed ALL was measured using a previously described competitive displacement assay. Only 13% of the untreated patients were considered to have impaired MTX transport whereas over 70% of the relapsed patients had evidence of impaired MTX transport. Northern analyses and quantitative RT-PCR for the reduced folate carrier (RFC) were performed on the RNA available from the leukemic blasts of 24 patients in whom MTX transport had been measured. Six of 9 samples with impaired MTX transport had decreased RFC expression (one had no detectable RFC expression), while three had no decrease in RFC expression. Acute myelocytic leukemia (AML) was studied to determine the basis of the decreased MTX polyglutamylation. Enzyme kinetics of the enzyme folylpolyglutamate synthetase (FPGS) were studied, demonstrating FPGS in the myeloid cell lines and patient samples had a higher Km for MTX as a substrate than lymphoid cells. Measuring gamma-glutamyl hydrolase enzyme activity allowed a more accurate prediction of steady state levels of MTX polyglutamates. A knowledge of the mechanisms of MTX resistance that occur in leukemic blasts obtained from patients may allow the development of therapeutic strategies to circumvent resistance. |
| Keywords: | acute granulocytic leukemia; review; methotrexate; metabolism; antimetabolites, antineoplastic; drug resistance; drug resistance, neoplasm; acute lymphocytic leukemia; antineoplastic antimetabolite; reduced folate carrier; gamma-glutamyl hydrolase; gamma glutamyl hydrolase; peptide synthase; peptide synthases; leukemia, myelocytic, acute; leukemia, lymphocytic, acute; humans; human; acute myelocytic leukemia; folylpolyglutamate synthase; folylpolyglutamate synthetase |
| Journal Title: | Advances in Experimental Medicine and Biology |
| Volume: | 457 |
| ISSN: | 0065-2598 |
| Publisher: | Springer |
| Date Published: | 1999-01-01 |
| Start Page: | 543 |
| End Page: | 550 |
| Language: | English |
| PUBMED: | 10500832 |
| PROVIDER: | scopus |
| DOI: | 10.1007/978-1-4615-4811-9_59 |
| DOI/URL: | |
| Notes: | Chapter 59 in "Drug Resistance in Leukemia and Lymphoma III" (ISBN: 978-1-4613-7180-9)-- Export Date: 16 August 2016 -- Source: Scopus |
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