Effect of diindolylmethane on Ca(2+) movement and viability in HA59T human hepatoma cells.

Archives of toxicology

PubMedID: 21409406

Cheng JS, Shu SS, Kuo CC, Chou CT, Tsai WL, Fang YC, Kuo LN, Yeh JH, Chen WC, Chien JM, Lu T, Pan CC, Cheng HH, Chai KL, Jan CR. Effect of diindolylmethane on Ca(2+) movement and viability in HA59T human hepatoma cells. Arch Toxicol. 2011;85(10):1257-66.
The effect of diindolylmethane, a natural compound derived from indole-3-carbinol in cruciferous vegetables, on cytosolic Ca(2+) concentrations ([Ca(2+)](i)) and viability in HA59T human hepatoma cells is unclear. This study explored whether diindolylmethane changed [Ca(2+)](i) in HA59T cells. The Ca(2+)-sensitive fluorescent dye fura-2 was applied to measure [Ca(2+)](i). Diindolylmethane at concentrations of 1-50 µM evoked a [Ca(2+)](i) rise in a concentration-dependent manner. The signal was reduced by removing Ca(2+). Diindolylmethane-induced Ca(2+) influx was not inhibited by nifedipine, econazole, SK&F96365, and protein kinase C modulators but was inhibited by aristolochic acid. In Ca(2+)-free medium, treatment with the endoplasmic reticulum Ca(2+) pump inhibitors thapsigargin or 2,5-di-tert-butylhydroquinone (BHQ) inhibited or abolished diindolylmethane-induced [Ca(2+)](i) rise. Incubation with diindolylmethane inhibited thapsigargin or BHQ-induced [Ca(2+)](i) rise. Inhibition of phospholipase C with U73122 reduced diindolylmethane-induced [Ca(2+)](i) rise. At concentrations of 10-75 µM, diindolylmethane killed cells in a concentration-dependent manner. The cytotoxic effect of diindolylmethane was not reversed by chelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid. Propidium iodide staining data suggest that diindolylmethane (25-50 µM) induced apoptosis in a concentration-dependent manner. Collectively, in HA59T cells, diindolylmethane induced a [Ca(2+)](i) rise by causing phospholipase C-dependent Ca(2+) release from the endoplasmic reticulum and Ca(2+) influx via phospholipase A(2)-sensitive channels. Diindolylmethane induced cell death that may involve apoptosis.