Store depletion and store‐operated Ca2+ current in human prostate cancer LNCaP cells: involvement in apoptosis

• DOI: 10.1111/j.1469-7793.2000.00071.x
• Publication Date: 2004-08-13T09:29:47Z
• Authors: Roman Skryma; Pascal Mariot; Xuefen Le Bourhis; Fabien Van Coppen...; Yaroslav Shuba; Fabien Vanden Abeele; Guillaume Legrand; Sandrine Humez; Benoni Boilly; Natalia Prevarskaya
• Keywords: Male; 0301 basic medicine; Patch-Clamp Techniques; Electric Conductivity; Prostatic Neoplasms; Apoptosis; Calcium-Transporting ATPases; [SDV.MHEP.UN] Life Sciences [q-bio]/Human health and pathology/Urology and Nephrology; 3. Good health; 03 medical and health sciences; [SDV.CAN] Life Sciences [q-bio]/Cancer; Microscopy, Fluorescence; Lanthanum; Nickel; [SDV.SP.PHARMA] Life Sciences [q-bio]/Pharmaceutical sciences/Pharmacology; Androgens; Tumor Cells, Cultured; Humans; Thapsigargin; Calcium; Calcium Channels

1. In the present study, we investigated the mechanisms involved in the induction of apoptosis by the Ca2+-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 Ca2+, the first phase of which was associated with depletion of intracellular stores and the second one with consecutive extracellular Ca2+ entry through plasma membrane, store-operated Ca2+ channels (SOCs). 3. For the first time we have identified and characterized the SOC-mediated membrane current (Istore) in prostate cells using whole-cell, cell-attached, and perforated patch-clamp techniques, combined with fura-2 microspectrofluorimetric and Ca2+-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 Ca2+ as a charge carrier was estimated at 3.2 +/- 0.4 pS. The channel has a high selectivity for Ca2+ over monovalent cations and is inhibited by Ni2+ (0.5-3 mM) and La3+ (1 microM). 5. Treatment of LNCaP cells with TG (0.1 microM) induced apoptosis as judged from morphological changes. Decreasing extracellular free Ca2+ to 200 nM or adding 0.5 mM Ni2+ enhanced TG-induced apoptosis. 6. The ability of TG to induce apoptosis was not reduced by loading the cells with intracellular Ca2+ chelator (BAPTA-AM). 7. These results indicate that in androgen-sensitive prostate cancer cells the depletion of intracellular Ca2+ stores may trigger apoptosis but that there is no requirement for the activation of store-activated Ca2+ current and sustained Ca2+ entry in induction and development of programmed cell death.