title: Rise of [Ca²⁺]i and apoptosis induced by M-3M3FBS in SCM1 human gastric cancer cells.
abstract: M-3M3FBS (2,4,6-trimethyl-N-(meta-3-trifluoromethyl-phenyl)-benzenesulfonamide is a presumed phospholipase C activator which induced Ca²⁺ movement and apoptosis in different cell models. How- ever, the effect of m-3M3FBS on cytosolic free Ca²⁺ concentrations ([Ca²⁺]i) and apoptosis in SCM1 human gastric cancer 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 between 5-50 μM increased [Ca²⁺]i in a concentration-dependent manner. The Ca²⁺ signal was reduced by half 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. Suppression of inositol 1,4,5-trisphosphate production with U73122 did not change m-3M3FBS- induced [Ca²⁺]i rise. At concentrations between 25 and 50 μM m-3M3FBS killed cells in a concentration- dependent manner. The cytotoxic effect of m-3M3FBS was not reversed by prechelating cytosolic Ca²⁺ with acetoxy-methyl ester of bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA/AM). Annexin V/propidium iodide staining data suggest that m-3M3FBS induced apoptosis at 25 and 50 μM. M-3M3FBS also increased levels of superoxide. Together, in human gastric cancer 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 reactive oxygen species production.
authors.affiliation: Department of Surgery, St. Joseph Hospital, Kaohsiung 80288, Taiwan, Republic of China.
authors.forename: Wei-Chuan
authors.initials: WC
authors.lastname: Chen
authors.forename: Chiang-Ting
authors.initials: CT
authors.lastname: Chou
authors.forename: Wen-Chin
authors.initials: WC
authors.lastname: Liou
authors.forename: Shiuh-Inn
authors.initials: SI
authors.lastname: Liu
authors.forename: Ko-Long
authors.initials: KL
authors.lastname: Lin
authors.forename: Ti
authors.initials: T
authors.lastname: Lu
authors.forename: Yi-Chau
authors.initials: YC
authors.lastname: Lu
authors.forename: Shu-Shong
authors.initials: SS
authors.lastname: Hsu
authors.forename: Jeng-Yu
authors.initials: JY
authors.lastname: Tsai
authors.forename: Wei-Chuan
authors.initials: WC
authors.lastname: Liao
authors.forename: Wei-Zhe
authors.initials: WZ
authors.lastname: Liang
authors.forename: Chung-Ren
authors.initials: CR
authors.lastname: Jan
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D006801:Humans; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D013449:Sulfonamides / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000502:physiology*; D000096926:Benzenesulfonamides
chemical_list: D002118:Calcium; D013449:Sulfonamides; D010738:Type C Phospholipases; C473783:2,4,6-trimethyl-N-(meta-3-trifluoromethylphenyl)benzenesulfonamide; D000096926:Benzenesulfonamides