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Store depletion and store‐operated Ca 2+ current in human prostate cancer LNCaP cells: involvement in apoptosis
Author(s) -
Skryma Roman,
Mariot Pascal,
Bourhis Xuefen,
Coppenolle Fabien,
Shuba Yaroslav,
Abeele Fabien Vanden,
Legrand Guillaume,
Humez Sandrine,
Boilly Bei,
Prevarskaya Natalia
Publication year - 2000
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2000.00071.x
Subject(s) - lncap , thapsigargin , extracellular , intracellular , apoptosis , bapta , chemistry , fura 2 , cancer cell , microbiology and biotechnology , biophysics , endocrinology , medicine , biology , biochemistry , cytosol , cancer , enzyme
1 In the present study, we investigated the mechanisms involved in the induction of apoptosis by the Ca 2+ ‐ATPase inhibitor thapsigargin (TG), in androgen‐sensitive human prostate cancer LNCaP cells. 2 Exposure of fura‐2‐loaded LNCaP cells to TG in the presence of extracellular calcium produced an increase in intracellular Ca 2+ , the first phase of which was associated with depletion of intracellular stores and the second one with consecutive extracellular Ca 2+ entry through plasma membrane, store‐operated Ca 2+ channels (SOCs). 3 For the first time we have identified and characterized the SOC‐mediated membrane current ( I store ) in prostate cells using whole‐cell, cell‐attached, and perforated patch‐clamp techniques, combined with fura‐2 microspectrofluorimetric and Ca 2+ ‐imaging measurements. 4 Istore in LNCaP cells lacked voltage‐dependent gating and displayed an inwardly rectifying current‐voltage relationship. The unitary conductance of SOCs with 80 mM Ca 2+ as a charge carrier was estimated at 3.2 ± 0.4 pS. The channel has a high selectivity for Ca 2+ over monovalent cations and is inhibited by Ni 2+ (0.5–3 mM) and La 3+ (1 μM). 5 Treatment of LNCaP cells with TG (0.1 μM) induced apoptosis as judged from morphological changes. Decreasing extracellular free Ca 2+ to 200 nM or adding 0.5 mM Ni 2+ enhanced TG‐induced apoptosis. 6 The ability of TG to induce apoptosis was not reduced by loading the cells with intracellular Ca 2+ chelator (BAPTA‐AM). 7 These results indicate that in androgen‐sensitive prostate cancer cells the depletion of intracellular Ca 2+ stores may trigger apoptosis but that there is no requirement for the activation of store‐activated Ca 2+ current and sustained Ca 2+ entry in induction and development of programmed cell death.