title: The TRPC channel blocker SKF 96365 inhibits glioblastoma cell growth by enhancing reverse mode of the Na(+) /Ca(2+) exchanger and increasing intracellular Ca(2+).
abstract: OBJECTIVE
  SKF 96365 is well known for its suppressing effect on human glioblastoma growth by inhibiting pre-activated transient receptor potential canonical (TRPC) channels and Ca(2+) influx. The effect of SKF 96363 on glioblastoma cells, however, may be multifaceted and this possibility has been largely ignored.
  
  
  METHODS
  The effects of SKF 96365 on cell cycle and cell viability of cultured human glioblastoma cells were characterized. Western blot, Ca(2+) imaging and patch clamp recordings were used to delineate cell death mechanisms. siRNA gene knockdown provided additional evidence.
  
  
  RESULTS
  SKF 96365 repressed glioblastoma cell growth via increasing intracellular Ca(2+) ([Ca(2+) ]i ) irrespective of whether TRPC channels were blocked or not. The effect of SKF 96365 primarily resulted from enhanced reverse operation of the Na(+) /Ca(2+) exchanger (NCX) with an EC50 of 9.79 μM. SKF 96365 arrested the glioblastoma cells in the S and G2 phases and activated p38-MAPK and JNK, which were all prevented by the Ca(2+) chelator BAPTA-AM or EGTA. The expression of NCX in glioblastoma cells was significantly higher than in normal human astrocytes. Knockdown of the NCX1 isoforms diminished the effect of SKF 96365 on glioblastoma cells.
  
  
  CONCLUSIONS
  At the same concentration, SKF 96365 blocks TRPC channels and enhances the reverse mode of the NCX causing [Ca(2+) ]i accumulation and cytotoxicity. This finding suggests an alternative pharmacological mechanism of SKF 96365. It also indicates that modulation of the NCX is an effective method to disrupt Ca(2+) homeostasis and suppress human glioblastoma cells.
authors.affiliation: Department of Anesthesiology, Emory University School of Medicine, Atlanta, GA, USA.
authors.forename: M
authors.initials: M
authors.lastname: Song
authors.forename: D
authors.initials: D
authors.lastname: Chen
authors.forename: S P
authors.initials: SP
authors.lastname: Yu
mesh_terms: D000634:Aminoquinolines / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004354:Drug Screening Assays, Antitumor; D005909:Glioblastoma / Q000188:drug therapy* / Q000473:pathology*; D006801:Humans; D019831:Sodium-Calcium Exchanger / Q000378:metabolism*; D013329:Structure-Activity Relationship; D050052:TRPC Cation Channels / Q000037:antagonists & inhibitors*; D014407:Tumor Cells, Cultured
chemical_list: D000634:Aminoquinolines; D000970:Antineoplastic Agents; D019831:Sodium-Calcium Exchanger; D050052:TRPC Cation Channels; C069657:1-(2-methylphenyl)-4-methylamino-6-methyl-2,3-dihydropyrrolo(3,2-c)quinoline; D002118:Calcium
keywords: Na+/Ca2+ exchanger; SKF 96365; TRPC channel; calcium; cell cycle; cell death; glioblastoma