Reduced Folate Carrier Mutations Are Not the Mechanism Underlying Methotrexate Resistance in Childhood Acute Lymphoblastic Leukemia

Yotam Kaufman, Stavit Drori, Peter D. Cole, Barton A. Kamen, Jenny Sirota, Ilan Ifergan, Myriam Weyl Ben Arush, Ronit Elhasid, Dvora Sahar, Gert Jan L. Kaspers, Gerrit Jansen, Larry H. Matherly, Gideon Rechavi, Amos Toren, Yehuda G. Assaraf

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

BACKGROUND. Although the majority of children with acute lymphoblastic leukemia (ALL) are cured with combination chemotherapy containing methotrexate (MTX), drug resistance contributes to treatment failure for a substantial fraction of patients. The primary transporter for folates and MTX is the reduced folate carrier (RFC). Impaired drug transport is a documented mechanism of MTX resistance in patients with ALL; however, to the authors' knowledge it is not known whether inactivating RFC mutations are a contributing factor. METHODS. The authors devised a genomic polymerase chain reaction-single strand conformational polymorphism assay followed by sequencing and screened the entire RFC coding region for sequence alterations in DNA from 246 leukemia specimens from patients with diverse ethnic variation, 24 at the time of recurrence and the rest at the time of diagnosis. This cohort was comprised of 203 β-precursor ALL specimens (82.5%), 32 T-lineage ALL specimens (13%), and 11 acute myeloblastic leukemia specimens (4.5%). RESULTS. Of 246 DNA samples, only 3 diagnosis β-precursor ALL specimens (1.2%) were found to harbor alterations in the RFC gene, including heterozygous single nucleotide changes resulting in D56H and D522N substitutions in the first extra-cellular loop and the C-terminus of this transporter, respectively. The third sample had a sequence alteration in exon 3 that could not be identified because of the lack of availability of DNA. CONCLUSIONS. Whereas inactivating RFC mutations are a frequent mechanism of MTX resistance in human leukemia cell lines and in patients with osteosarcoma, they are not common and do not appear to play any significant role in intrinsic or acquired resistance to MTX in childhood leukemia. This is the first study of RFC mutations in multiple pediatric leukemia specimens.

Original languageEnglish (US)
Pages (from-to)773-782
Number of pages10
JournalCancer
Volume100
Issue number4
DOIs
StatePublished - Feb 15 2004
Externally publishedYes

Keywords

  • Acute lymphoblastic leukemia (ALL)
  • Chemotherapy
  • Drug resistance
  • Drug transport
  • Methotrexate (MTX)
  • Mutations
  • Reduced folate carrier (RFC)

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Fingerprint

Dive into the research topics of 'Reduced Folate Carrier Mutations Are Not the Mechanism Underlying Methotrexate Resistance in Childhood Acute Lymphoblastic Leukemia'. Together they form a unique fingerprint.

Cite this