cytochrome-c-t and Lymphoma--Mantle-Cell

This study was aimed to explore the effect of midazolam on mantle cell lymphoma cell line JeKo-1 and the relevant mechanisms. Effects of midazolam on the proliferation and apoptosis of JeKo-1 cells were observed by CCK8 assay and flow cytometry, respectively. Effect of midazolam on the expression of BCL-2, cytochrome C (Cyto-C), pro-caspase-9, pro-caspase-8 and pro-caspase-3 protein were detected by Western blot. The results showed that midazolam could inhibit the growth of JeKo-1 cells significantly and the concentration of 50% growth inhibition (IC50) at 48 hours was approximately 40 µmol/L. After treatment with 20, 40, 80 µmol/L midazolam for 48 hours, a dose-dependent apoptosis of JeKo-1 cells could be observed. Meanwhile, a dose-dependent reduction of BCL-2, pro-caspase-9 and pro-caspase-3 protein expression and increase of Cyto-C protein expression in JeKo-1 cells were found, but the expression of pro-caspase-8 protein did not change. It is concluded that midazolam possibly initiates the mitochondrial pathway, not the death receptor pathway, by reducing the expression of BCL-2, leading in turn to the releasing of Cyto-C in mitochondria, then activating caspase-9 and caspase-3 protein, triggers the caspase cascade, and induces the apoptosis of JeKo-1 cells ultimately.

Topics: Apoptosis; Caspase 3; Caspase 8; Caspase 9; Cell Line, Tumor; Cytochromes c; Humans; Lymphoma, Mantle-Cell; Midazolam; Proto-Oncogene Proteins c-bcl-2

TRAIL (TNF (tumour necrosis factor)-related apoptosis-inducing ligand) a putative anti-cancer cytokine induces apoptosis through DISC (death-inducing signalling complex)-mediated activation of caspase-8 and/or cleavage of Bid. TRAIL is relatively specific for tumour cells but primary chronic lymphocytic leukaemia and mantle cell lymphoma (MCL) cells are resistant. Herein, we show that cellular metabolism influences cell death and that MCL cells (Z138 cell line) can survive/proliferate in glucose-free media by switching from aerobic glycolysis to 'coupled' oxidative phosphorylation. Extracellular flux analysis and mitochondrial inhibitors reveal that in the absence of glycolysis, Z138 cells have enhanced respiratory capacity coupled to ATP synthesis, similar to 'classical' state 3 mitochondria. Conversely, 2-deoxyglucose (2DG) blocked glycolysis and partially inhibited glycolytic-dependent oxidative phosphorylation, resulting in a 50% reduction in cellular ATP levels. Also, 2DG sensitised Z138 cells to TRAIL and induced a marked decrease in caspase-8, -3, cFLIP(S), Bid and Mcl-1 expression but Bak remained unchanged, altering the Mcl-1/Bak ratio, facilitating cytochrome c release and cell death. Conversely, under glucose-free conditions, Z138 cells were less sensitive to TRAIL with reduced TRAIL-R1/R2 surface receptor expression and impaired DISC formation. Anti-apoptotic proteins Bcl-2 and XIAP were up-regulated while pro-apoptotic BAX was down-regulated. Additionally, mitochondria had higher levels of cytochrome c and ultrastucturally exhibited a condensed configuration with enhanced intracristal spaces. Thus, metabolic switching was accompanied by mitochondrial proteome and ultrastructural remodelling enabling enhanced respiration activity. Cytochrome c release was decreased in glucose-free cells, suggesting that either pore formation was inhibited or that cytochrome c was more tightly bound. Glucose-free Z138 cells were also resistant to intrinsic cell death stimuli (ABT-737 and ionising radiation). In summary, in MCL cells, the anti-glycolytic effects of 2DG and glucose restriction produced opposite effects on TRAIL-induced cell death, demonstrating that mitochondrial metabolism directly modulates sensitivity of tumour cells to apoptosis.

Topics: Aerobiosis; Apoptosis; Cell Line, Tumor; Culture Media; Cytochromes c; Glycolysis; Humans; Lymphoma, Mantle-Cell; Mitochondria; Oxidative Phosphorylation; TNF-Related Apoptosis-Inducing Ligand