PMID: 6978176May 1, 1982Paper

Establishment of methotrexate-resistant human acute lymphoblastic leukemia cells in culture and effects of folate antagonists

Cancer Research
T OhnoshiJ F Holland

Abstract

A human acute lymphoblastic T-cell line, MOLT-3, was fed with Roswell Park Memorial Institute Medium 1640-10% fetal bovine serum-antibiotics, containing increasing concentrations of methotrexate (MTX). After 10 months of feeding, the cells became resistant to 10(-7) M MTX; resistance was not reversed when the cells were placed in the original MTX-free medium. At 10(-7) M MTX, the concentration which produced complete inhibition of the parent MOLT-3 cell growth, the resistant cells were not inhibited at all. On a 50% inhibitory concentration basis, the resistant cells were approximately 30-fold more resistant to MTX. The parent MOLT-3 and the resistant line had the same doubling time of approximately 36 hr. There were no differences in light microscopic morphology. MOLT-3 produced loose colonies on 0.5% agar enriched with fetal bovine serum, whereas the colonies of the resistant line were tightly packed. The development of resistance was accompanied by a 4- to 5-fold decrease in [3H]MTX transport (MOLT-3/MTXt). Kinetic analysis of MTX uptake showed that the resistant subline did not have an altered Km for MTX (6.6 microM) but had a decreased Vmax of about 20% of the parent cell line. These data suggest that either the number of ...Continue Reading

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