title: Effect of calmidazolium on [Ca2+]i and viability in human hepatoma cells.
abstract: The effect of calmidazolium on cytosolic free Ca2+ concentrations ([Ca2+]i) and viability has not been explored in human hepatoma cells. This study examined whether calmidazolium altered [Ca2+]i and caused cell death in HA59T cells. [Ca2+]i and cell viability were measured using the fluorescent dyes fura-2 and WST-1, respectively. Calmidazolium at concentrations > or =1 microM increased [Ca2+]i in a concentration-dependent manner with an EC50 value of 1.5 microM. The Ca2+ signal was reduced partly by removing extracellular Ca2+. Calmidazolium induced Mn2+ quench of fura-2 fluorescence implicating Ca2+ influx. The Ca2+ influx was insensitive to L-type Ca2+ entry blockers, but was inhibited partly by enhancing or inhibiting protein kinase C activity. In Ca2+-free medium, after pretreatment with 1 microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor), calmidazolium-induced [Ca2+]i rises were largely inhibited; and conversely, calmidazolium pretreatment totally suppressed thapsigargin-induced [Ca2+]i rises. Inhibition of phospholipase C with 2 microM U73122 did not change calmidazolium-induced [Ca2+]i rises. At concentrations between 1 and 15 microM, calmidazolium induced apoptosis-mediated cell death. Collectively, in HA59T hepatoma cells, calmidazolium induced [Ca2+]i rises by causing Ca2+ release from the endoplasmic reticulum in a phospholipase C-independent manner, and Ca2+ influx via protein kinase C-regulated Ca2+ entry pathway. Calmidazolium caused cytotoxicity via apoptosis.
authors.affiliation: Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan.
authors.forename: Wei-Chuan
authors.initials: WC
authors.lastname: Liao
authors.forename: Chorng-Chih
authors.initials: CC
authors.lastname: Huang
authors.forename: He-Hsiung
authors.initials: HH
authors.lastname: Cheng
authors.forename: Jue-Long
authors.initials: JL
authors.lastname: Wang
authors.forename: Ko-Long
authors.initials: KL
authors.lastname: Lin
authors.forename: Jin-Shiung
authors.initials: JS
authors.lastname: Cheng
authors.forename: Kuo-Liang
authors.initials: KL
authors.lastname: Chai
authors.forename: Pei-Te
authors.initials: PT
authors.lastname: Hsu
authors.forename: Jeng-Yu
authors.initials: JY
authors.lastname: Tsai
authors.forename: Yi-Chien
authors.initials: YC
authors.lastname: Fang
authors.forename: Yih-Chau
authors.initials: YC
authors.lastname: Lu
authors.forename: Hong-Tai
authors.initials: HT
authors.lastname: Chang
authors.forename: Jong-Khing
authors.initials: JK
authors.lastname: Huang
authors.forename: Chiang-Ting
authors.initials: CT
authors.lastname: Chou
authors.forename: Chung-Ren
authors.initials: CR
authors.lastname: Jan
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D006528:Carcinoma, Hepatocellular / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D005456:Fluorescent Dyes / Q000494:pharmacology; D016257:Fura-2 / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000008:administration & dosage / Q000633:toxicity*; D008113:Liver Neoplasms / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D013778:Tetrazolium Salts / Q000494:pharmacology
chemical_list: C110656:2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium; D005456:Fluorescent Dyes; D007093:Imidazoles; D013778:Tetrazolium Salts; C031938:calmidazolium; D011493:Protein Kinase C; D002118:Calcium; D016257:Fura-2