Article
Proliferation of human lens epithelial cells (hLEC) is determined by sustained intracellular calcium level
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Authors
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A. Meissner
- University of Rostock, Institute of Physiology, Rostock
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T. Noack
- University of Rostock, Institute of Physiology, Rostock
| Published: | September 18, 2006 |
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Outline
Text
Objective
It has been shown, that the T-type calcium channel blocker Mibefradil inhibits proliferation in human lens epithelial cells [1]. T-type und L-type calcium channels are substantially present in hLEC and total calcium currents are inhibited by Mibefradil at concentrations of 1 mM [2]. The anti-proliferative mechanism remains unclear, since other effects than calcium channel blockade might be involved at these concentrations of the drug.
Methods
Epithelial cells of the human lens (HLE-B3, ATCC) were investigated with cell culture techniques; cell proliferation was determined by incubating a defined cell number with different concentrations of Mibefradil, Verapamil and other calcium channel modulating drugs over 48 h. Cell number was determined by staining with Trypan blue solution. Western Blot analysis was accomplished under standard conditions, using a-pERK, a-ERK, a-caspase and a-Cav1.2 and a-Cav3.1. Calcium measurements were performed using Fura-2 technique.
Results
Mibefradil inhibited proliferation at 1 mM (IC50), whereas Verapamil in concentrations of 10 mM. The activation of MAPK 3 was reduced by both antagonists in the concentration ranges, in which they inhibited proliferation. Mibefradil also induced activation of caspase-3. Mitogenic HLE-B3 cells reacted more sensitive to a treatment with Mibefradil as to Verapamil possibly caused by a higher expression of T-type Ca-channels. The L-type calcium channel opener, Bay K 8644, had clear proliferative effects on hLECs: during the presence of this drug, the anti-proliferative action of Mibefradil was strongly attenuated.
Conclusions
Caspase-3 activation and MAPK 3 inhibition are linked to a reduction of intracellular calcium level which can be modulated by calcium channel blockade. Moreover, the action of the calcium channel opener Bay K 8644 strongly indicates, that proliferation of hLECs is linked to intracellular sustained calcium levels, which are also sensitive to Mibefradil.
Supported by the DFG No 269/5
