title: Neutral sphingomyelinase 2 modulates cytotoxic effects of protopanaxadiol on different human cancer cells.
abstract: BACKGROUND
  Some of ginsenosides, root extracts from Panax ginseng, exert cytotoxicity against cancer cells through disruption of membrane subdomains called lipid rafts. Protopanaxadiol (PPD) exhibits the highest cytotoxic effect among 8 ginsenosides which we evaluated for anti-cancer activity. We investigated if PPD disrupts lipid rafts in its cytotoxic effects and also the possible mechanisms.
  
  
  METHODS
  Eight ginsenosides were evaluated using different cancer cells and cell viability assays. The potent ginsenoside, PPD was investigated for its roles in lipid raft disruption and downstream pathways to apoptosis of cancer cells. Anti-cancer effects of PPD was also investigated in vivo using mouse xenograft model.
  
  
  RESULTS
  PPD consistently exerts its potent cytotoxicity in 2 cell survival assays using 5 different cancer cell lines. PPD disrupts lipid rafts in different ways from methyl-β-cyclodextrin (MβCD) depleting cholesterol out of the subdomains, since lipid raft proteins were differentially modulated by the saponin. During disruption of lipid rafts, PPD activated neutral sphingomyelinase 2 (nSMase 2) hydrolyzing membrane sphingomyelins into pro-apoptotic intracellular ceramides. Furthermore, PPD demonstrated its anti-cancer activities against K562 tumor cells in mouse xenograft model, confirming its potential as an adjunct or chemotherapeutic agent by itself in vivo.
  
  
  CONCLUSIONS
  This study demonstrates that neutral sphingomyelinase 2 is responsible for the cytotoxicity of PPD through production of apoptotic ceramides from membrane sphingomyelins. Thus neutral sphingomyelinase 2 and its relevant mechanisms may potentially be employed in cancer chemotherapies.
authors.affiliation: College of Pharmacy, Gachon University, Incheon, Korea.
authors.forename: Bonggoo
authors.initials: B
authors.lastname: Park
authors.forename: Yong-Moon
authors.initials: YM
authors.lastname: Lee
authors.forename: Jae-Sung
authors.initials: JS
authors.lastname: Kim
authors.forename: Youl
authors.initials: Y
authors.lastname: Her
authors.forename: Ju Hee
authors.initials: JH
authors.lastname: Kang
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Oh
authors.forename: Hwan-Mook
authors.initials: HM
authors.lastname: Kim
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003603:Cytotoxins / Q000008:administration & dosage*; D005260:Female; D036145:Ginsenosides / Q000008:administration & dosage*; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009369:Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000235:genetics; D005894:Panax / Q000737:chemistry*; D012502:Sapogenins / Q000008:administration & dosage*; D013108:Sphingomyelin Phosphodiesterase / Q000235:genetics / Q000378:metabolism*
chemical_list: D003603:Cytotoxins; D036145:Ginsenosides; D012502:Sapogenins; C491484:SMPD3 protein, human; D013108:Sphingomyelin Phosphodiesterase; C062916:protopanaxadiol
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