Ethanol Mediates Cell Cycle Arrest and Apoptosis in SK-N-SH Neuroblastoma Cells
Maria Lee1, Byoung-Joon Song2, Yongil Kwon3
1Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea.
Background:
The mechanisms of cell or organ damage by chronic alcohol consumption are still poorly understood. The present study aimed to investigate the role of the mitogen-activated protein kinases during ethanol-induced damage to SK-N-SH neuroblastoma cells.
Methods:
Cells were treated with ethanol and subsequently analyzed for cell morphology, viability, and DNA fragmentation. Immunoblot analysis was performed to assess various proteins levels associated with cell cycle arrest and apoptosis after ethanol exposure.
Results:
Ethanol induced time- and dose-dependent cell death in SK-N-SH cells and increased c-Jun N-terminal protein kinase (JNK) activity in a time- and concentration dependent manner. In contrast, p38 kinase activity increased transiently. After treatment with JNK or p38 kinase inhibitors, ethanol-induced cell death significantly reduced. Ethanol-induced cell death was accompanied by increased cytochrome c release and caspase 3 activity observed at 12 h. In contrast, the level of anti-apoptotic Bcl-2 protein did not change. Ethanol also increased the phosphorylation of p53 and p53 activation was followed by an increase in the p21 tumor suppressor protein accompanied by a gradual decrease in phospho-Rb protein.
Conclusion:
Our results suggest that ethanol mediates apoptosis of neuroblastoma cells by stimulating p53-related cell cycle arrest mediated through activation of the JNK-related pathway.
Insights
Chronic alcohol consumption causes neuroblastoma cell death by activating the c-Jun N-terminal protein kinase (JNK) pathway, leading to p53-related cell cycle arrest and apoptosis.
Area of Science:
- Neuroscience
- Cell Biology
- Toxicology
Background:
- Mechanisms of chronic alcohol-induced cell and organ damage are not fully understood.
- Ethanol's impact on neuroblastoma cells (SK-N-SH) requires further investigation.
Purpose of the Study:
- Investigate the role of mitogen-activated protein kinases (MAPKs) in ethanol-induced neuroblastoma cell damage.
- Elucidate the signaling pathways involved in alcohol-related neurotoxicity.
Main Methods:
- SK-N-SH cells treated with ethanol.
- Analysis of cell morphology, viability, and DNA fragmentation.
- Immunoblotting to assess protein levels related to cell cycle and apoptosis.
Main Results:
- Ethanol induced dose- and time-dependent cell death and increased c-Jun N-terminal protein kinase (JNK) activity.
- p38 kinase activity showed transient increase; JNK and p38 inhibitors reduced ethanol-induced cell death.
- Ethanol increased cytochrome c release, caspase 3 activity, p53 phosphorylation, p21 levels, and decreased phospho-Rb, while Bcl-2 levels remained unchanged.
Conclusions:
- Ethanol induces apoptosis in neuroblastoma cells via JNK pathway activation.
- This activation stimulates p53-related cell cycle arrest, contributing to neurotoxicity.
- MAPK signaling pathways are critical in mediating ethanol-induced neuroblastoma cell damage.
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