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Blood, 1 February 2005, Vol. 105, No. 3, pp. 1198-1203. Prepublished online as a Blood First Edition Paper on July 1, 2004; DOI 10.1182/blood-2003-12-4299.
Submitted December 19, 2003
Department of Medicine, Mount Sinai School of Medicine, New York, NY, USA * Corresponding author; email: samuel.waxman{at}mssm.edu.
Arsenic trioxide (As2O3) is an effective agent for the treatment of acute promyelocytic leukemia by induction of partial differentiation and apoptosis. As2O3, at therapeutic concentrations (1-2µM), induced apoptosis in Raji, but not in Jurkat lymphoma cells, which inversely correlated with glutathione-S-transferase µ (GSTP1), but not GSTM1 and GSTA1, expression and activity. GSTP1 mRNA, protein level and activity were high in Jurkat cells but undetectable in Raji cells. Stable transfection of GSTP1 into Raji cells decreased the amount of As2O3-induced apoptosis. Apoptosis induced by therapeutic concentration of As2O3 in Raji cells is related to increasing intracellular H2O2, but not JNK activation. Forced expression of GSTP1 in Raji cells decreased basal H2O2 and diminished the increment of H2O2 after therapeutic concentration of As2O3 treatment. Exogenous H2O2 was removed more rapidly which correlated with a greater decrease in reduced glutathione level in Raji clones expressing GSTP1 than in those clones without GSTP1 expression. Overexpression of GSTP1 in transfected Raji clones was also found to decrease the retention of As2O3. These data suggest that GSTP1 blocks As2O3-induced apoptosis in lymphoma cells by decreasing intracellular amount of H2O2 by catabolism and/or by inhibition of H2O2 production by decreasing intracellular retention of As2O3.
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