RT Journal Article
SR Electronic
T1 Glutathione Content and Glutathione-<em>S</em>-transferase Expression in 1,3-Bis(2-chloroethyl)-1-nitrosourea-resistant Human Malignant Astrocytoma Cell Lines
JF Cancer Research
JO Cancer Res
FD American Association for Cancer Research
SP 6976
OP 6980
VO 50
IS 21
A1 Ali-Osman, Francis
A1 Stein, Donna E.
A1 Renwick, Alexander
YR 1990
UL http://cancerres.aacrjournals.org/content/50/21/6976.abstract
AB γ-l-glutamyl-l-cysteinylglycine (GSH) has been shown to inactivate 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and quench DNA cross-link precursors of BCNU. Because of the central role of 2-chloroethylnitrosoureas in brain tumor chemotherapy, we investigated the intracellular GSH content and the expression of specific glutathione-S-transferases (GSTs) in three human malignant astrocytoma cell lines (UWR1, UWR2, and UWR3) of varying BCNU resistance to determine the interrelationship of these parameters with brain tumor BCNU resistance. GSH was assayed by ion-exchange high performance liquid chromatography after derivatization with 1-fluoro-2,4 dinitrobenzene. Both bulk and specific GST (acid, near-neutral, and basic) activities were examined using substrates that show high specificities to the different GSTs. Western blot analyses with antisera against GST-α, -µ, and -π subunits were also performed on partially purified GST from the cells of each cell line. The results showed GSH content of 91, 46.5, and 28.3 nmol GSH/mg protein for UWR1, UWR2, and UWR3, respectively. Bulk GST activity (with 1-chloro-2,4-dinitrobenzene as substrate) also correlated with increasing BCNU resistance. Of the three GST classes examined by both substrate specificities and Western blotting, only the expression of the acidic form, GST-π, correlated significantly with the rank order of BCNU resistance of the cell lines. GST-µ and -α were present in only trace amounts in all three cell lines. ©1990 American Association for Cancer Research.