Malabaricone-A Induces A Redox Imbalance That Mediates Apoptosis in U937 Cell Line

Abstract

BackgroundThe ‘two-faced’ character of reactive oxygen species (ROS) plays an important role in cancer biology by acting both as secondary messengers in intracellular signaling cascades and sustaining the oncogenic phenotype of cancer cells, while on the other hand, it triggers an oxidative assault that causes a redox imbalance translating into an apoptotic cell death.Principal FindingsUsing a tetrazolium [{3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl}-2H-tetrazolium] based cell viability assay, we evaluated the cytotoxicity of a plant derived diarylnonanoid, malabaricone-A on leukemic cell lines U937 and MOLT-3. This cytotoxicity hinged on its ability to cause a redox imbalance via its ability to increase ROS, measured by flow cytometry using 5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate and by decreasing glutathione peroxidase activity. This redox imbalance mediated apoptosis was evident by an increase in cytosolic [Ca2+], externalization of phosphatidyl serine as also depolarization of the mitochondrial membrane potential as measured by flow cytometry. There was concomitant peroxidation of cardiolipin, release of free cytochrome c to cytosol along with activation of caspases 9, 8 and 3. This led to cleavage of the DNA repair enzyme, poly (ADP-ribose) polymerase that caused DNA damage as proved by labeling with 4′,6-diamidino-2-phenylindole (DAPI); furthermore, terminal deoxy ribonucleotide transferase catalysed incorporation of deoxy uridine triphosphate confirmed DNA nicking and was accompanied by arrest of cell cycle progression.ConclusionsTaken together, compounds like MAL-A having pro-oxidant activity mediate their cytotoxicity in leukemic cells via induction of oxidative stress triggering a caspase dependent apoptosis.

Nickel(II) complexes having different configurations controlled by N,N,O-donor Schiff-base ligands in presence of isothiocyanate as co-ligand: Synthesis, structures, comparative biological activity and DFT study

“…We have found that treatment of the EAC cells with the compounds increased ROS generation by more than 2fold. Researchers have established that cancer cells have higher basal level of ROS and any agent that increases ROS generation is termed chemotherapeutic agent (Manna et al, 2012) [45]. In the present study we have shown that our compounds increased the level of ROS in EAC cells which ultimately led to EAC cell death (Fig.…”

Apoptotic and Autophagic Effects of Sesbania grandiflora Flowers in Human Leukemic Cells

“…To examine the effect of F2 fraction on generation of ROS, CM-H 2 DCFDA – lipid soluble, membrane permeable non-fluorescent reduced derivative of 2,7-dichlorofluorescein was used based on the evidence that the acetate groups of CM-H 2 DCFDA are removed by esterase cleavage intracellularly to produce hydrophilic, non-fluorescent dye Dichlorodihydrofluorescein (DCFH 2 ) which is subsequently oxidized by ROS to form a highly fluorescent product Dichlorofluorescein (DCF). Thus, the fluorescence generated is directly proportional to the quantum of ROS generated [20]. The effect of IC 50 concentration of F2 (18.6 µg/ml for U937, 20.9 µg/ml for THP1, 24.6 µg/ml for HL60, 26.1 µg/ml for Raji) on generation of ROS (0–2 h) was measured in cells (2.5×10 5 /ml).…”

A Defective Oxidative Burst and Impaired Antigen Presentation are Hallmarks of Human Visceral Leishmaniasis

“…To monitor the levels of reactive oxygen species (ROS) irrespective of their site of generation, PBMCs (5×10 5 ) were stained with CMH 2 DCFDA (5 μM, 30 min, 37°C) and fluorescence of CMDCF acquired on a flow cytometer [10].…”

“…To measure the levels of non-protein thiols, PBMCs (5× 10 5 ) were initially incubated at 37°C for 30 min in an ATP depletion buffer (21 mM HEPES buffer, 137 mM NaCl, 5 mM KCl, 0.7 mM NaH 2 PO 4 and 20 mM sodium azide, 0.5 ml); cells were then washed with PBS, stained with CMFDA (50 nM, 15 min, 37°C) and fluorescence of CMF was acquired on a flow cytometer [10].…”