The T/C+C/C genotypes of MiR-499a may contribute to an increased risk of BQ-related OSF, but a decreased risk of OSCC. miR-499a T>C influences the expression levels of miR-499a-5p during the tumorigenesis of OSCC.

The effect of the natural product diindolylmethane (DIM) on cytosolic Ca(2+) concentrations ([Ca(2+)]i) and viability in MDCK renal tubular cells was explored. The Ca(2+)-sensitive fluorescent dye fura-2 was applied to measure [Ca(2+)]i. DIM at concentrations 1-50 μM induced a [Ca(2+)]i rise in a concentration-dependent manner. The response was reduced partly by removing Ca(2+). DIM induced Mn(2+) influx leading to quenching of fura-2 fluorescence. DIM-evoked Ca(2+) entry was suppressed by nifedipine, econazole, SK&F96365 and protein kinase C modulators. In the absence of extracellular Ca(2+), incubation with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin (TG) or 2,5-di-tert-butylhydroquinone (BHQ) greatly inhibited DIM-induced [Ca(2+)]i rise. Incubation with DIM abolished TG or BHQ-induced [Ca(2+)]i rise. Inhibition of phospholipase C with U73122 reduced DIM-induced [Ca(2+)]i rise by 50%. At 1, 10, 40 and 50 μM, DIM slightly enhanced cell proliferation. The effect of 50 μM DIM was reversed by chelating cytosolic Ca(2+) with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid. In sum, in MDCK cells, DIM induced a [Ca(2+)]i rise by evoking phospholipase C-dependent Ca(2+) release from the endoplasmic reticulum and Ca(2+) entry via protein kinase C-sensitive store-operated Ca(2+) channels. DIM did not induce cell death.

Celecoxib has been shown to have antitumor effect in previous studies but the mechanisms are unclear. The effect of celecoxib on cytosolic Ca2+ concentrations ([Ca2+]i) and viability in HA59T human hepatoma cells was explored. The Ca2+-sensitive fluorescent dye fura-2 was applied to measure [Ca2+]i. Celecoxib at concentrations of 10–50 μM induced a [Ca2+]i rise in a concentration-dependent manner. The response was reduced by 80% by removing Ca2+. Celecoxib induced Mn2+ influx, leading to quenching of fura-2 fluorescence. Celecoxib-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 inhibitor thapsigargin nearly abolished celecoxib-induced [Ca2+]i rise. Incubation with celecoxib abolished thapsigargin-induced [Ca2+]i rise. Inhibition of phospholipase C with U73122 abolished celecoxib-induced [Ca2+]i rise. At 1–50 μM, celecoxib inhibited cell viability by less than 20%, which was not reversed by chelating cytosolic Ca2+ with 1,2-bis(2-aminophenoxy)ethane-N, N, N′, N′-tetraacetic acid/acetoxy methyl (BAPTA/AM). Celecoxib (10–50 μM) also induced apoptosis. In sum, in HA59T hepatoma cells, celecoxib 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. Celecoxib also caused cell death via apoptosis.