1,2-bis(2-aminophenoxy)ethane-N,N,N'N'-tetraacetic acid (BAPTA-AM) inhibits caffeine-induced apoptosis in human neuroblastoma cells

Neferine and lianzixin extracts have protective effects on undifferentiated caffeine-damaged PC12 cells

BACKGROUND

The embryos of Nelumbo nucifera Gaertn seeds, lianzixin, are used in China as food and traditional herbal medicine. Principal therapeutic indications are insomnia, anxiety and pyrexia. Caffeine is a psychostimulant and excessive use predisposes to cell damage and neurotoxicity. We aimed to investigate the potential protect effect of Neferine and lianzixin extracts on undifferentiated caffeine-damaged phaeochromocytoma cells (PC12 cells).

METHODS

A cell damage model based on undifferentiated PC12 was established with caffeine. Effect of Lianzixin extracts (total alkaloids, alcohol extract and water extract) and neferine on caffeine-damaged PC12 cells was evaluated. Cell viability was assessed using the methyl thiazolyl tetrazolium (MTT) assay, cellular morphology by inverted microscope, the nucleus by Hoechst 33342 staining and cleaved poly ADP-ribose polymerase (PARP) expression by western blot analysis.

RESULTS

Lianzixin extracts (total alkaloids, alcohol extract and water extract) and neferine improved the viability of PC12 cells damaged by caffeine. The morphology of PC12 cells pretreated with neferine, or alcohol or water extract of lianzixin aggregated and attached better than caffeine-damaged cells, but cells pretreated with total alkaloids of lianzixin showed abnormal morphology. Compared with caffeine-damaged cells, cells pretreated with neferine, or alcohol or water extract of lianzixin showed a notable increase in nucleus staining and an obvious decrease in cleaved PARP expression.

CONCLUSIONS

Lianzixin extracts and neferine have protective effects against caffeine-induced damage in PC12 cells, which laid a foundation for finding a new medicine value of Lianzixin.

Dual blockade of the A1 and A2A adenosine receptor prevents amyloid beta toxicity in neuroblastoma cells exposed to aluminum chloride

In a previous work we have shown that exposure to aluminum (Al) chloride (AlCl3) enhanced the neurotoxicity of the amyloid beta(25-35) fragment (Abeta(25-35)) in neuroblastoma cells and affected the expression of Alzheimer's disease (AD)-related genes. Caffein, a compound endowed with beneficial effects against AD, exerts neuroprotection primarily through its antagonist activity on A2A adenosine receptors (A2AR), although it also inhibits A1Rs with similar potency. Still, studies on the specific involvement of these receptors in neuroprotection in a model of combined neurotoxicity (Abeta(25-35)+AlCl3) are missing. To address this issue, cultured SH-SY5Y cells exposed to Abeta(25-35)+AlCl3 were assessed for cell viability, morphology, intracellular ROS activity and expression of apoptosis-, stress- and AD-related proteins. To define the role of A1R and A2ARs, pretreatment with caffein, specific receptor antagonists (DPCPX or SCH58261) or siRNA-mediated gene knockdown were delivered. Results indicate that AlCl3 treatment exacerbated Abeta(25-35) toxicity, increased ROS production, lipid peroxidation, β-secretase-1 (BACE1) and amyloid precursor protein (APP). Interestingly, SCH58261 successfully prevented toxicity associated to Abeta(25-35) only, whereas pretreatment with both DPCPX and SCH58261 was required to fully avert Abeta(25-35)+AlCl3-induced damage, suggesting that A1Rs might also be critically involved in protection during combined toxicity. The effects of caffein were mimicked by both N-acetyl cysteine, an antioxidant, and desferrioxamine, likely acting through distinct mechanisms. Altogether, our data establish a novel protective function associated with A1R inhibition in the setting of combined Abeta(25-35)+AlCl3 neurotoxicity, and expand our current knowledge on the potential beneficial role of caffein to prevent AD progression in subjects environmentally exposed to aluminum.

Clofibrate-induced apoptosis is mediated by Ca2+-dependent caspase-12 activation

The mechanism of fibrate-induced myopathy was investigated in this report. When clofibrate (30 to 300 microM) was applied to L6 rat skeletal myoblasts, dose-dependently apoptosis was observed within 24 h. In the apoptotic myoblasts, a caspase-12 cleavage was observed at 2 h and with following caspases-9 and -3-related cascade activation. In contrast, the neutral protease calpain, that is a key enzyme in ER stress-related apoptosis via caspase-12 activation, was significantly decreased during apoptosis. Next, the authors evaluated a role of calcium-dependent signal(s). When clofibrate was added into medium, cytosolic calcium concentration was rapidly and persistently increased. On the other hand, an addition of 10 mM EGTA depressed sustained calcium phase, and concurrent myoblasts apoptosis was completely inhibited. Taken together, our findings indicate that the clofibrate-induced myopathy is triggered by Ca2+ influx, then activated cytosolic caspase-12 through calpain-independent cascade, and consequently caused apoptotic DNA fragmentation.

Caffeine induces apoptosis of human umbilical vein endothelial cells through the caspase-9 pathway

Caffeine is known to modulate placental and fetal umbilical circulation. It is demonstrated that apoptosis of human umbilical vein endothelial cells (HUVECs) is associated with placental umbilical vascular diseases. The present study was conducted to investigate the effects of caffeine on apoptosis of HUVECs. Isolated HUVECs were cultured under serum-free conditions for 24 h, and then treated with graded concentrations of caffeine (30, 100 and 300 microM) for additional 24 h and 48 h. The number of viable HUVECs was determined by cell counting. Apoptotic HUVECs were assessed by Hoechst33342 dye staining. The expression of caspase-9, caspase-8, caspase-3 and poly(ADP-ribose) polymerase (PARP) was assessed by Western blot analysis. Caffeine induced a dose- and time-dependent decrease in the number of viable HUVECs. Caffeine at concentrations higher than 100 microM significantly increased the percentage of apoptotic HUVECs. Caffeine at concentrations higher than 100 microM significantly increased cleaved caspase-9, caspase-3 and PARP expression in HUVECs at 24-h treatment compared with untreated cultures, whereas 30 microM caffeine significantly increased only caspase-3 expression at 24 h. Caffeine did not affect cleaved caspase-8 expression at 48 h. These results suggest that high concentrations of caffeine inhibit cell growth of HUVECs and induce apoptosis through the caspase-9 pathway.