Melatonin induces apoptosis in human neuroblastoma cancer cells
Guillermo García-Santos1, Isaac Antolín, Federico Herrera
1Departamento de Morfología y Biología Celular, Facultad de Medicina de la Universidad de Oviedo, Oviedo, Spain.
Abstract:
Low concentrations (nanomolar) of melatonin had been previously shown to inhibit cell proliferation in several cancer cell lines as well as in experimental animal models. Additionally, cell growth inhibition and differentiation of prostate cancer cell lines by high concentrations (micromolar to millimolar) of melatonin have been recently reported. In the present paper, we show the induction of apoptosis by high doses of melatonin in the human neuroblastoma cell line SK-N-MC. We found accumulation of cells in the G2/M cell cycle phase and induction of cellular death, measured as lactate dehydrogenase (LDH) released into the culture medium, under millimolar concentration of melatonin. Apoptosis was evaluated using 4,6-diamidino-2-phenylindole staining, DNA gel electrophoresis, electron microscopy, and annexin V binding. Apoptosis progressed through the classical pathway, which involves caspase-3 activation. Cell death was dose and time-dependent; the lowest effective concentration of melatonin was 100 microm. Treatment with 1 mm melatonin for 6 days induced cell death in 75% of the cells. This novel finding shows that a nontoxic natural indoleamine may be potential therapy for some types of human neuroblastomas.
Insights
High concentrations of melatonin induce apoptosis in human neuroblastoma cells, causing cell cycle arrest and death. This natural compound shows potential as a novel therapy for neuroblastomas.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Melatonin (indoleamine) at nanomolar concentrations inhibits cancer cell proliferation.
- High melatonin concentrations (micromolar to millimolar) have shown effects on prostate cancer cell lines.
Purpose of the Study:
- To investigate the effect of high-dose melatonin on the human neuroblastoma cell line SK-N-MC.
- To determine if melatonin induces apoptosis in neuroblastoma cells.
Main Methods:
- Cell culture of SK-N-MC human neuroblastoma cells.
- Treatment with millimolar concentrations of melatonin.
- Assessment of cell cycle phase (G2/M arrest).
- Measurement of cell death via lactate dehydrogenase (LDH) release.
- Apoptosis evaluation using DAPI staining, DNA gel electrophoresis, electron microscopy, and annexin V binding.
- Caspase-3 activation assay.
Main Results:
- High melatonin concentrations (millimolar) induced apoptosis in SK-N-MC cells.
- Accumulation of cells in the G2/M phase of the cell cycle was observed.
- Cell death was dose- and time-dependent, with 100 micromolar being the lowest effective concentration.
- Treatment with 1 millimolar melatonin for 6 days resulted in 75% cell death.
- Apoptosis followed the classical pathway involving caspase-3 activation.
Conclusions:
- High doses of melatonin induce apoptosis in human neuroblastoma cells (SK-N-MC).
- Melatonin treatment leads to G2/M cell cycle arrest and caspase-3 activation.
- This study suggests melatonin as a potential therapeutic agent for neuroblastomas.
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