title: Immunohistochemistry of dihydrofolate reductase in methotrexate-sensitive and -resistant human cell lines by flow cytometry: a comparison with the cytochemical tetrazolium salt method.
abstract: Dihydrofolate reductase (DHFR, EC 1.5.1.3) is an enzyme involved in the metabolism of nucleic acids; it is also an important target for folate antagonists such as methotrexate (MTX). The distribution and expression of DHFR both in human HeLa BU-25 cell line and in methotrexate-resistant (MTX-R) variant, deriving from the human VA2-B cell line (having the DHFR gene amplified) was studied by tetrazolium salt method and by flow cytometric analysis. The immunohistochemical labelling of DHFR was achieved by using the streptavidinbiotinilated complex technique. DHFR activity was low in the human HeLa BU-25 cell line, while it was very high in the MTX-R cell line; the activity level increased with the increasing concentration of the MTX. The results obtained with cytochemical and immunohistochemical technique were compared. These findings showed that the hyperproduction of DHFR is strictly related with the cells having the DHFR gene amplified. Since MTX resistance is a common finding in the cells of patients with acute leukaemia, these studies may be extended to tumour-bearing patients at onset and following chemotherapy with methotrexate.
authors.affiliation: Department of Animal Biology, University of Pavia, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Nano
authors.forename: G
authors.initials: G
authors.lastname: Gerzeli
authors.forename: C
authors.initials: C
authors.lastname: Morandi
authors.forename: C
authors.initials: C
authors.lastname: Arisi
mesh_terms: D002460:Cell Line; D004247:DNA / Q000032:analysis; D004351:Drug Resistance; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D008727:Methotrexate / Q000494:pharmacology*; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism*; D013778:Tetrazolium Salts
chemical_list: D013778:Tetrazolium Salts; D004247:DNA; D013762:Tetrahydrofolate Dehydrogenase; D008727:Methotrexate