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Br J Pharmacol. 2010 Jul;160(5):1171-84. doi: 10.1111/j.1476-5381.2010.00746.x.

Activation of c-Jun N-terminal kinase is essential for mitochondrial membrane potential change and apoptosis induced by doxycycline in melanoma cells.

Author information

1
Department of Internal Medicine, Chi-Mei Medical Center, Tainan, Taiwan.

Abstract

BACKGROUND AND PURPOSE:

Tetracyclines were recently found to induce tumour cell death, but the early processes involved in this cytotoxic effect remain unclear.

EXPERIMENTAL APPROACH:

Viability of human and mouse melanoma cells was determined by MTT assay and flow cytometry. Kinase/protein/caspase activation was measured by Western blotting and mitochondrial membrane potential (DeltaPsi(m)) was analyzed by fluorescence microscopy and flow cytometry.

KEY RESULTS:

Human and mouse melanoma cells were treated with doxycycline or minocycline but only doxycycline was cytotoxic. This cell death (apoptosis) in A2058 cells involved activation of caspase-3, -7 and -9 and contributed to inhibition, by doxycycline, of matrix metalloproteinase (MMP) activity and migration of these cells. Doxycycline induced intra-cellular reactive oxygen species (ROS) production, apoptosis signal-regulated kinase 1 (ASK1), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) activation at an early stage of treatment and induced mitochondrial cytochrome c release into cytosol and DeltaPsi(m) change during apoptosis. The JNK inhibitor/small interference RNA inhibited doxycycline-induced JNK activation, DeltaPsi(m) change and apoptosis, but did not affect ASK1 activation, suggesting a role of ASK1 for JNK activation in melanoma cell apoptosis. Two ROS scavengers reduced doxycycline-induced JNK and caspase activation, and apoptosis. Taken together, the results suggest the involvement of a ROS-ASK1-JNK pathway in doxycycline-induced melanoma cell apoptosis.

CONCLUSIONS AND IMPLICATIONS:

We have shown a promising cytotoxic effect of doxycycline on melanoma cells, have identified ROS and ASK1 as the possible initiators and have demonstrated that JNK activation is necessary for doxycycline-induced melanoma cell apoptosis.

PMID:
20590610
PMCID:
PMC2936026
DOI:
10.1111/j.1476-5381.2010.00746.x
[Indexed for MEDLINE]
Free PMC Article

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