Cisplatin (CDDP) changes intracellular calcium concentration ([Ca2+]i) in various cell lines, while elevated [Ca2+]i induces apoptosis. We have previously shown that CDDP could elevate [Ca2+]i in MCF-7 cells. Here we investigate the source of [Ca2+]i by modulating calcium channels and transport mechanisms. Changes in the [Ca2+]i were recorded using florescence microscopy and the calcium-sensitive fluorescent dye, Fluo-4. CDDP (0.001 – 0.1 µM) and [Ca2+]i modulators, (caffeine; 10mM, nimodipine; 10M, ionomycin; 10µM, thapsigargin; 500nM, and 2-APB; 50µM) were administered to cultured MCF-7 cells via a bath perfusion system. Cytotoxicity tests were performed using MTS and FACS assays at CDDP 100pM - 10mM. Viability tests were done following 24h incubation with CDDP. CDDP induced a concentration-dependent increase of [Ca2+]i. A concentration of CDDP 0.1µM triggered the largest elevation of [Ca2+]i with a 120 percent increase (n=19). Pre-application of the calcium channel blocker, nimodipine reduced this elevation significantly (46.6 percent increase; n=26) as well as the IP3 receptor blocker 2-APB (71.4% increase; n=52). Surprisingly, when [Ca2+]i was elevated due to a pre-application of caffeine (either ionomycin or thapsigargin), the subsequent application of CDDP was also significantly reduced compared to control conditions (n=15; 37.8 percent, n=32; 34.9 percent, n=21; 53.7 percent increase respectively). CDDP concentration dependently elevates [Ca2+]i by Ca2+ entry and Ca2+ release from the stores. The pre-elevation of [Ca2+]i, through releasing Ca2+ from the stores, reduces this elevation significantly. The exact mechanisms remain unclear and further investigations are required to determine the mechanisms and pathways that are involved in the elevation of [Ca2+]i.


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  • Received: 15 May 2012
  • Accepted: 15 May 2012
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