ascorbic-acid and benzyloxycarbonylvalyl-alanyl-aspartyl-fluoromethyl-ketone

The compromised antioxidant defense system in chronic lymphocytic leukemia (CLL) suggested a potential use for reactive oxygen species (ROS) generating arsenic trioxide (ATO) and ascorbic acid. While both ATO and ascorbic acid mediate cytotoxicity in CLL B cells as single agents, the efficacy of ATO is enhanced by ascorbic acid. This effect is dependent on increased ROS accumulation, as pretreatment of B-CLL cells with a glutathione reducing buthionine sulfoximine or catalase inhibiting aminotriazole, enhanced ATO/ascorbic acid-mediated cytotoxicity. Pretreatment with reducing agents such as catalase, or thiol antioxidant, N-acetyl cysteine or GSH also abrogated ATO/ascorbic acid-mediated cytotoxicity. Furthermore, Hu1D10-mediated cell death was enhanced with ATO and ascorbic acid, thus justifying potential combination of ATO/arsenic trioxide therapy with antibodies such as Hu1D10 that also cause accumulation of ROS.

Topics: Amino Acid Chloromethyl Ketones; Amitrole; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Arsenic Trioxide; Arsenicals; Ascorbic Acid; B-Lymphocytes; Buthionine Sulfoximine; Catalase; Cell Line, Tumor; Cysteine Proteases; Cysteine Proteinase Inhibitors; Drug Evaluation, Preclinical; Drug Synergism; Enzyme Activation; Glutathione; Humans; Leukemia, Lymphocytic, Chronic, B-Cell; Neoplasm Proteins; Oxidants; Oxidative Stress; Oxides; Reactive Oxygen Species

Intracerebral hemorrhage (ICH) induces neurovascular injury via poorly defined mechanisms. The aim of this study was to determine whether gliovascular communication may restrict hemorrhagic vascular injury. Hemin, a hemoglobin by-product, concentration- and time-dependently increased apoptotic cell death in mouse bEnd.3 cells and in primary human brain microvascular endothelial cells, at least in part, via a caspase-3 dependent pathway. Cell death was preceded by a NFκB-mediated increase in inflammatory gene expression, including upregulation of inducible nitric oxide synthase (iNOS) expression and activity. Functionally, inhibition of iNOS or the addition of a peroxynitrite decomposition catalyst reduced cell death. Interestingly, co-treatment with astrocyte-conditioned media (ACM) reversed hemin-induced NFκB activation, nitrotyrosine formation, and apoptotic cell death, at least in part, via the release of the endogenous antioxidant, reduced glutathione (GSH). Prior treatment of astrocytes with the GSH-depleting agent, DL-buthionine (S,R)-sulfoximine or direct addition of diethyl maleate, a thiol-depleting agent, to ACM reversed the observed protection. In contrast, neither exogenous GSH nor the GSH precursor, N-acetylcysteine, was protective in bEnd.3 cells. Together, these data support an important role for astrocyte-derived GSH in the maintenance of oxidative balance in the vasculature and suggest therapeutic targeting of the GSH system may reduce neurological injury following ICH.

Topics: Acetylcysteine; Amino Acid Chloromethyl Ketones; Animals; Antioxidants; Apoptosis; Ascorbic Acid; Astrocytes; Brain; Caspase 3; Cells, Cultured; Curcumin; Dose-Response Relationship, Drug; Enzyme Inhibitors; Glutathione; Hemin; Humans; L-Lactate Dehydrogenase; Mice; Microvessels; Neuroprotective Agents; Nitric Oxide Synthase Type II; Peroxynitrous Acid; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerases; Time Factors

Vincristine (VCR), a microtubule interfering anti-cancer agent, plays a key role in the treatment of childhood acute lymphoblastic leukaemia (ALL). The route of VCR induced apoptosis in ALL cells is not well defined. In this study we demonstrated caspase-9 and -3 activation in vivo in bone marrow leukaemic cells of a child with newly diagnosed ALL, after treatment with a single dose of VCR. We hypothesized that VCR induced apoptosis in ALL cells proceeds by a mitochondrial controlled pathway. We further studied the route of VCR induced apoptosis in Jurkat acute lymphoblastic leukaemia cells. First we showed that VCR induces activation of caspase-9 and -3 in Jurkat cells. With the caspase-9 inhibitor Z-LEHD-FMK we proved that caspase-9 was activated prior to caspase-3. Loss of mitochondrial transmembrane potential was independent of caspase-9 activation. To confirm the mitochondrial role in VCR induced apoptosis, the effect of blocking the mitochondrial route upstream of caspase-9 activation was investigated at two different levels: reactive oxygen species (ROS) scavenging and Bcl-2 overexpression. Generation of ROS was detected early in Jurkat cells during VCR exposure. Ascorbic acid, a ROS scavenger, inhibited ROS generation as well as caspase-9 and -3 activation and cell death induced by VCR. Furthermore, in Bcl-2 overexpressing Jurkat cells mitochondrial membrane potential changes, caspase-9 and -3 activation and cell death upon VCR exposure were decreased, in comparison to parental Jurkat cells. However, generation of ROS was not decreased in Jurkat cells with Bcl-2 overexpression. We concluded that ROS play a regulatory role in the initial phase of a mitochondrial controlled pathway of VCR induced apoptosis in Jurkat cells.

Topics: Amino Acid Chloromethyl Ketones; Antineoplastic Agents, Phytogenic; Apoptosis; Ascorbic Acid; Blotting, Western; Bone Marrow Cells; Caspase 3; Caspase 9; Caspase Inhibitors; Caspases; Enzyme Activation; Enzyme Inhibitors; Humans; Jurkat Cells; Membrane Potentials; Mitochondria; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-bcl-2; Reactive Oxygen Species; Vincristine