3,3′‐Diindolylmethane Alters Ca2+ Homeostasis and Viability in MG63 Human Osteosarcoma Cells
Abstract: The effect of the natural product 3,3′‐diindolylmethane (DIM) on cytosolic Ca2+ concentrations ([Ca2+]i) and viability in MG63 human osteosarcoma cells was explored. The Ca2+‐sensitive fluorescent
dye fura‐2 was applied to measure [Ca2+]i. DIM at concentrations of 40–80 μM induced a [Ca2+]i rise in a concentration‐dependent manner. The response was reduced partly by removing Ca2+. DIM‐evoked Ca2+
entry was suppressed by nifedipine, econazole, SK&F96365 and protein kinase C modulators. In the absence of extracellular Ca2+, incubation with the endoplasmic reticulum Ca2+ pump inhibitors thapsigargin or 2,5‐di‐tert‐butylhydroquinone (BHQ)
inhibited or abolished DIM‐induced [Ca2+]i rise. Incubation with DIM also inhibited thapsigargin or BHQ‐induced [Ca2+]i rise. Inhibition of phospholipase C with U73122 abolished DIM‐induced [Ca2+]i rise.
At concentrations of 10–50 μM, DIM killed cells in a concentration‐dependent manner. This cytotoxic effect was not altered by chelating cytosolic Ca2+ with 1,2‐bis(2‐aminophenoxy)ethane‐N,N,N′,N′‐tetraacetic acid (BAPTA).
Annexin V/propidium iodide staining data implicate that DIM (20 and 40 μM) induced apoptosis in a concentration‐dependent manner. In sum, in MG63 cells, DIM induced a [Ca2+]i rise by evoking phospholipase C‐dependent Ca2+ release from
the endoplasmic reticulum and Ca2+ entry via protein kinase C‐sensitive store‐operated Ca2+ channels. DIM caused cell death that may involve apoptosis.
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Document Type: Research Article
Department of Orthopedics, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
Department of Rehabilitation, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
Department of Nursing, Tzu Hui Institute of Technology; Pingtung, Taiwan
Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
Publication date: 2012-04-01
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