title: Co-application of arsenic trioxide (As2O3) and cisplatin (CDDP) on human SY-5Y neuroblastoma cells has differential effects on the intracellular calcium concentration ([Ca2+]i) and cytotoxicity.
abstract: Arsenic trioxide (As(2)O(3)) and cisplatin (CDDP) are clinically relevant chemotherapeutics which modulate the intracellular calcium concentration ([Ca(2+)](i)) by different mechanisms: As(2)O(3) depletes intracellular calcium stores while CDDP triggers an influx of Ca(2+). We investigate whether co-application of As(2)O(3) and CDDP has an effect on [Ca(2+)](i) homeostasis, resulting in an increase of cytotoxicity/apoptosis in human SY-5Y neuroblastoma cells. Confocal imaging with Ca(2+)-sensitive dye (fluo-4) was used for investigating [Ca(2+)](i) dynamics. The induction of cell death was assayed using Trypan blue exclusion and Hoechst 33347 staining. Application of As(2)O(3) (1microM) or CDDP (1microM) increased [Ca(2+)](i). The largest elevation was observed when the basic [Ca(2+)](i) concentration was low. Both, transient and sustained [Ca(2+)](i)-increases were observed in response to a single application of As(2)O(3) or CDDP. Sustained increase showed clear additive effects when both drugs were co-applied. The magnitude of the [Ca(2+)](i)-increase depends on the order of application; the most pronounced effect occurred when the cells were preincubated with CDDP followed by a co-application with As(2)O(3). The sustained [Ca(2+)](i) elevations resulted in increased cytotoxicity and apoptosis. Therefore, co-treatment with CDDP and As(2)O(3) may be a more effective anti-cancer therapy then either agent alone.
authors.affiliation: Institut für Physiologie, Universitätsklinikum Essen, Universität Duisburg Essen, Essen, Germany.
authors.forename: Dennis Alexander
authors.initials: DA
authors.lastname: Günes
authors.forename: Ana-Maria
authors.initials: AM
authors.lastname: Florea
authors.forename: Frank
authors.initials: F
authors.lastname: Splettstoesser
authors.forename: Dietrich
authors.initials: D
authors.lastname: Büsselberg
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000008:administration & dosage; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000008:administration & dosage / Q000633:toxicity*; D003603:Cytotoxins / Q000008:administration & dosage / Q000633:toxicity; D004359:Drug Therapy, Combination; D006801:Humans; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism*; D009447:Neuroblastoma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D010087:Oxides / Q000008:administration & dosage / Q000633:toxicity*
chemical_list: D001152:Arsenicals; D003603:Cytotoxins; D010087:Oxides; D002945:Cisplatin; D000077237:Arsenic Trioxide; D002118:Calcium