benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone and thymoquinone

We show that HTLV-1 negative leukemia cells are more sensitive to TQ due to higher levels of drug-induced reactive oxygen species (ROS). PreG1 population in HTLV-1 negative Jurkat and CEM was higher than HTLV-1 transformed HuT-102 and MT-2 cells. Peripheral blood mononuclear cells were more resistant. Hoechst staining indicated more features of apoptosis, namely nuclear blebs and shrunken nuclei in HuT-102 than Jurkat. A greater depletion of the antioxidant enzyme glutathione occurred in Jurkat, which consequently led to an increase in ROS, loss of mitochondrial membrane potential, cytochrome c release, activation of caspases 3 and 9, and cleavage of PARP. Treatment with z-VAD-fmk partially reversed TQ-induced apoptosis, suggesting a caspase-dependent mechanism. N-acetyl cysteine prevented apoptosis providing evidence that cell death is ROS-dependent. Catalase prevented apoptosis to a lesser extent than NAC. In summary, TQ induces apoptosis in adult T cell leukemia/lymphoma by decreasing glutathione and increasing ROS, and levels of ROS underlie the differential cellular response to TQ. Our data suggest a potential therapeutic role for TQ in sensitizing HTLV-I-negative T-cell lymphomas.

Topics: Amino Acid Chloromethyl Ketones; Analysis of Variance; Animals; Apoptosis; Benzoquinones; Catalase; Glutathione; Human T-lymphotropic virus 1; Humans; Jurkat Cells; Lymphoma, T-Cell; Membrane Potential, Mitochondrial; Reactive Oxygen Species; T-Lymphocytes