title: Effect of fluoxetine on [Ca²⁺]i and cell viability in OC2 human oral cancer cells.
abstract: Fluoxetine is a serotonin-specific reuptake inhibitor that has been used as an antidepressant. This study examined the effect of fluoxetine on cytosolic free Ca²⁺ concentrations ([Ca2⁺]i) and viability in OC2 human oral cancer cells. The Ca²⁺-sensitive fluorescent dye fura-2 was used to measure [Ca²⁺]i, and the water soluble tetrazolium (WST-1) regent was used to measure viability. Fluoxetine induced [Ca²⁺]i rises concentration-dependently. The response was reduced by half by removing extracellular Ca²⁺. Fluoxetine-induced Ca²⁺ entry was enhanced by activation of protein kinase C (PKC) with phorbol 12-myristate 13 acetate (PMA) but was inhibited by inhibition of the enzyme with GF109203X. In Ca²⁺-free medium, treatment with the endoplasmic reticulum Ca²⁺ pump inhibitor 2,5-di-tert-butylhydroquinone (BHQ) or thapsigargin abolished fluoxetine-evoked [Ca²⁺]i rise. Conversely, treatment with fluoxetine inhibited BHQ/thapsigargin-evoked [Ca²⁺]i rise. Inhibition of phospholipase C (PLC) with U73122 abolished fluoxetine-induced [Ca²⁺]i rise. At 20-80 μM, fluoxetine decreased cell viability concentration-dependently, which was not altered by chelating cytosolic Ca²⁺ with 1,2-bis(2- aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA/AM). At 20-60 μM, fluoxetine induced apoptosis as detected by annexin V/propidium iodide (PI) staining. Together, in OC2 cells, fluoxetine induced [Ca²⁺]i rises by evoking PLC-dependent Ca²⁺ release from the endoplasmic reticulum and Ca²⁺ entry via PKC-regulated mechanisms. Fluoxetine also caused Ca²⁺-independent apoptosis.
authors.affiliation: Department of Rehabilitation, Kaohsiung Veterans General Hospital, Kaohsiung 81362 Taiwan, Republic of China.
authors.forename: Ko-Long
authors.initials: KL
authors.lastname: Lin
authors.forename: Chiang-Ting
authors.initials: CT
authors.lastname: Chou
authors.forename: Jin-Shiung
authors.initials: JS
authors.lastname: Cheng
authors.forename: Hong-Tai
authors.initials: HT
authors.lastname: Chang
authors.forename: Wei-Zhe
authors.initials: WZ
authors.lastname: Liang
authors.forename: Chun-Chi
authors.initials: CC
authors.lastname: Kuo
authors.forename: I-Li
authors.initials: IL
authors.lastname: Chen
authors.forename: Li-Ling
authors.initials: LL
authors.lastname: Tseng
authors.forename: Pochuen
authors.initials: P
authors.lastname: Shieh
authors.forename: Ru-Fang
authors.initials: RF
authors.lastname: Wu
authors.forename: Daih-Huang
authors.initials: DH
authors.lastname: Kuo
authors.forename: Chung-Ren
authors.initials: CR
authors.lastname: Jan
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005473:Fluoxetine / Q000494:pharmacology*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008301:Maleimides / Q000494:pharmacology; D009062:Mouth Neoplasms / Q000378:metabolism / Q000473:pathology*; D011493:Protein Kinase C / Q000378:metabolism; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology
chemical_list: D002118:Calcium; D004791:Enzyme Inhibitors; D005473:Fluoxetine; D007211:Indoles; D008301:Maleimides; D011493:Protein Kinase C; D017367:Selective Serotonin Reuptake Inhibitors; C070515:bisindolylmaleimide I