M-3M3FBS-induced Ca² ⁺ movement and apoptosis in HA59T human hepatoma cells.
The effect of 2,4,6-trimethyl-N-(meta-3-trifluoromethyl-phenyl)-benzenesulfonamide (m-3M3FBS), a presumed phospholipase C activator, on cytosolic free Ca² ⁺ concentrations ([Ca² ⁺ ]i ) in HA59T human hepatoma cells is unclear.  This study explored whether m-3M3FBS elevated basal [Ca² ⁺ ]i levels in suspended cells by using fura-2 as a Ca² ⁺ -sensitive fluorescent dye.  M-3M3FBS at concentrations of 10- 50 μM increased [Ca² ⁺ ]i in a concentration-dependent fashion.  The Ca² ⁺ signal was reduced partly by removing extracellular Ca² ⁺ .  M-3M3FBS-induced Ca² ⁺ influx was inhibited by nifedipine, econazole, SK&F96365, aristolochic acid, and GF109203X.  In Ca² ⁺ -free medium, 50 μM m-3M3FBS pretreatment inhibited the [Ca² ⁺ ]i rise induced by the endoplasmic reticulum Ca² ⁺ pump inhibitor thapsigargin. Conversely, pretreatment with thapsigargin partly reduced m-3M3FBS-induced [Ca² ⁺ ]i rise.  Inhibition of inositol 1,4,5-trisphosphate formation with U73122 did not alter m-3M3FBS-induced [Ca² ⁺ ]i rise. At concentrations between 10 and 40 μM m-3M3FBS killed cells in a concentration-dependent manner. The cytotoxic effect of m-3M3FBS was not reversed by prechelating cytosolic Ca² ⁺ with 1,2-bis(2- aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA).  Annexin V/propidium iodide staining data suggest that m-3M3FBS induced apoptosis in a concentration-dependent manner.  M-3M3FBS also increased levels of reactive oxygen species.  Together, in human hepatoma cells, m-3M3FBS induced a [Ca² ⁺ ]i rise by inducing phospholipase C-independent Ca² ⁺ release from the endoplasmic reticulum and Ca² ⁺  entry via protein kinase C-sensitive store-operated Ca² ⁺  channels.  M-3M3FBS induced cell death that might involve apoptosis via mitochondrial pathways.
Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan, Republic of China.
Shiuh-Inn
SI
Liu
Ko-Long
KL
Lin
Ti
T
Lu
Yi-Chau
YC
Lu
Shu-Shong
SS
Hsu
Jeng-Yu
JY
Tsai
Wei-Chuan
WC
Liao
Fong-Dee
FD
Huang
Chao-Chuan
CC
Chi
Wei-Zhe
WZ
Liang
Li-Ling
LL
Tseng
An-Jen
AJ
Chiang
Chung-Ren
CR
Jan
D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D017382:Reactive Oxygen Species / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000378:metabolism*; D000096926:Benzenesulfonamides
D002118:Calcium; D017382:Reactive Oxygen Species; D013449:Sulfonamides; D010738:Type C Phospholipases; C473783:2,4,6-trimethyl-N-(meta-3-trifluoromethylphenyl)benzenesulfonamide; D000096926:Benzenesulfonamides