Effects of the antianginal drug fendiline on Ca2+ movement in hepatoma cells

This study investigated the effect of the anti-anginal drug, fendiline, on intracellular free Ca2+ levels ([Ca2+]i)inHA/ 22 human hepatoma cells by using fura-2 as a fluorescent Ca2+ dye. Fendiline (1-100 μM) increased [Ca2+]i with an EC50 of 25 μM. Removal of extracellular Ca2+ reduced the [Ca2+]i signals by 51-5%. Fendiline (10 μM)-induced Ca2+release was abolished by pretreatment with 1 μM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor). Inhibition of phospholipase C with 2 μM 1-(6-((17β 3 methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H pyrrole-2,5-dione (U73122) did not alter 10 μM fendilineinducedCa2+ release.Severalothercalmodulinantagonists, such as phenoxybenzamine (100-200 μM), trifluoperazine (5-50 μM),andfluphenazine N-chloroethane(2-100 μM), hadno effect on[Ca2+]i. Together, it wasfound that fendiline increased [Ca2+]i in human hepatoma cells by discharging Ca2+ from the endoplasmic reticulum in an inositol 1,4,5 trisphosphate-independent manner and by inducing Ca2+entry. This effect of fendiline does not appear to be via antagonism of calmodulin.

Download Full-text

Celecoxib-induced increase in cytosolic Ca2+ levels and apoptosis in HA59T human hepatoma cells

Human & Experimental Toxicology ◽

10.1177/0960327112472996 ◽

2014 ◽

Vol 33 (11) ◽

pp. 1089-1098

Author(s):

H-H Cheng ◽

C-T Chou ◽

Y-C Lu ◽

T Lu ◽

C-C Chi ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Protein Kinase C ◽

Protein Kinase ◽

Phospholipase C ◽

Hepatoma Cells ◽

Dependent Manner ◽

Human Hepatoma ◽

Human Hepatoma Cells ◽

Fura 2 ◽

Kinase C

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.

Download Full-text