chrysin and Leukemia--Lymphocytic--Chronic--B-Cell

We investigated the effect of chrysin on isolated normal and chronic lymphocytic leukemia (CLL) B-lymphocytes and their isolated mitochondria. We report that a selective and significant increase in cytotoxicity, intracellular reactive oxygen species, mitochondrial membrane potential collapse, ADP/ATP ratio, caspase 3 activation and finally apoptosis in chrysin-treated CLL B- lymphocytes. Also we determined that chrysin selectively inhibits complex II and ATPases in cancerous mitochondria. In this study we proved that the ability of chrysin to promote apoptosis in CLL B-lymphocytes performed by selectively targeting of mitochondria. Our findings may provide a potential therapeutic approach for using chrysin to target mitochondria in CLL B-lymphocytes.

Topics: Adenosine Diphosphate; Adenosine Triphosphatases; Adenosine Triphosphate; Antineoplastic Agents; Apoptosis; B-Lymphocytes; Carrier Proteins; Caspase 3; Cell Survival; Drug Evaluation, Preclinical; Drug Screening Assays, Antitumor; Electron Transport Complex II; Flavonoids; Humans; Inhibitory Concentration 50; Leukemia, Lymphocytic, Chronic, B-Cell; Membrane Potential, Mitochondrial; Membrane Proteins; Mitochondrial Proton-Translocating ATPases; Mitochondrial Swelling; Oxidative Phosphorylation; Reactive Oxygen Species; Tumor Cells, Cultured

Chronic lymphocytic leukemia (CLL) develops due to an imbalance between apoptosis and proliferation of B lymphocytes. Chrysin induced apoptosis in leukemia cell lines such as U937, MO7e, THP-1 and HL-60, but there has not yet been data demonstrating the apoptotic effect of chrysin on CLL cells. Therefore, in our investigation we examined the cytotoxicity of chrysin against two leukemia cell lines, MOLT-4 and JVM-13, peripheral blood lymphocytes isolated from B-CLL patients and peripheral blood mononuclear cells (PBMC) from healthy individuals in vitro. The effect of chrysin on viability of MOLT-4 and JVM-13 cell lines, B-CLL cells derived from 28 patients and PBMC from 16 healthy subjects was determined by MTT assay. The type of cell death induced by chrysin was verified by Annexin V/7AAD assay and acridine orange and ethidium bromide (AO/EB) staining assay. Intracellular localisation and endogenic expression of apoptotic proteins including Bax, Bcl-2, cytochrome c and caspase-3 were determined by flow cytometry and fluorescent microscopy. Our results demonstrated that exposure of MOLT-4, JVM-13 cell lines and B-CLL cells to the concentration of chrysin of 10μM and higher selectively decreased viability of cells in this cell population, but not in the PBMC derived from healthy subjects; LC50 values of chrysin for B-CLL cells were 51μM for 24 hours and 32μM for 48 hours of incubation, respectively. Our findings demonstrated that chrysin induces the activation of proapoptotic Bax and decreases the expression of antiapoptotic Bcl-2 protein, releases cytochrome c from mitochondria into cytosol and cleavages/activates caspase-3, subsequently leading to the activation of apoptosis of B-CLL cells. Together, these findings suggest that chrysin selectively induces apoptosis of peripheral blood lymphocytes isolated from human chronic lymphocytic leukemia patients via mitochondrial pathway in vitro and that it might have a promising role as a potential future antileukemic remedy.

Topics: Apoptosis; bcl-2-Associated X Protein; Case-Control Studies; Caspase 3; Cell Line, Tumor; Cytochromes c; Cytosol; Flavonoids; Humans; Leukemia, Lymphocytic, Chronic, B-Cell; Leukocytes, Mononuclear; Mitochondria; Proto-Oncogene Proteins c-bcl-2