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Zinc Depletion‐induced Apoptosis in Human Breast Cancer MDA‐MB‐231 Cells Is Calcium‐dependent
Author(s) -
Xu Zhaoming,
Purtzki Markus
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.928.25
Subject(s) - intracellular , calcium in biology , calcium , apoptosis , chemistry , bapta , calcium metabolism , endocrinology , medicine , biology , biochemistry , organic chemistry
We have previously observed an association between zinc depletion‐induced apoptosis and an elevated expression of eNOS in MDA‐MB‐231 cells. Since eNOS is sensitive to changes in intracellular [Ca 2+ ] i , we hypothesized that zinc depletion‐induced apoptosis is calcium‐dependent. To test this hypothesis, MDA‐MB‐231 cells were cultured in DMEM supplemented with FBS (10%) for 3 days. Zinc depletion was achieved by incubating the cells with TPEN (0 or 20 μM) for 0–6 h. Zinc depletion resulted in a sustained elevation in intracellular calcium level after 3 h and a 20‐fold increase in caspase‐3 activity at 6 h ( p < 0.05). Chelating intracellular Ca 2+ with BAPTA‐AM (10–50 μM) reduced caspase‐3 activity by 82%–96% ( p < 0.05). Further, zinc depletion also resulted in a 2‐fold increase in mitochondrial superoxide level ( p < 0.05). Blocking mitochondria calcium transport with Ruthenium red (25 μM) reduced caspase‐3 activity by 50% ( p < 0.05). Inhibiting intracellular Ca 2+ channel with 2‐APB (50–150 μM) and U‐73122 (2–20 μM) reduced caspase‐3 activity by 30–50% and 20–70%, respectively ( p < 0.05). In summary, these results showed that zinc depletion altered cellular calcium homeostasis resulting in an elevated intracellular calcium level required for apoptosis in MDA‐MB‐231 cells. ( Supported by NSERC ).