title: Synergistic Action of Genistein and Calcitriol in Immature Osteosarcoma MG-63 Cells by SGPL1 Up-Regulation.
abstract: BACKGROUND
  Phytoestrogens such as genistein, the most prominent isoflavone from soy, show concentration-dependent anti-estrogenic or estrogenic effects. High genistein concentrations (>10 μM) also promote proliferation of bone cancer cells in vitro. On the other hand, the most active component of the vitamin D family, calcitriol, has been shown to be tumor protective in vitro and in vivo. The purpose of this study was to examine a putative synergism of genistein and calcitriol in two osteosarcoma cell lines MG-63 (early osteoblast), Saos-2 (mature osteoblast) and primary osteoblasts.
  
  
  METHODS
  Thus, an initial screening based on cell cycle phase alterations, estrogen (ER) and vitamin D receptor (VDR) expression, live cell metabolic monitoring, and metabolomics were performed.
  
  
  RESULTS
  Exposure to the combination of 100 μM genistein and 10 nM calcitriol reduced the number of proliferative cells to control levels, increased ERß and VDR expression, and reduced extracellular acidification (40%) as well as respiratory activity (70%), primarily in MG-63 cells. In order to identify the underlying cellular mechanisms in the MG-63 cell line, metabolic profiling via GC/MS technology was conducted. Combined treatment significantly influenced lipids and amino acids preferably, whereas metabolites of the energy metabolism were not altered. The comparative analysis of the log2-ratios revealed that after combined treatment only the metabolite ethanolamine was highly up-regulated. This is the result: a strong overexpression (350%) of the enzyme sphingosine-1-phosphate lyase (SGPL1), which irreversibly degrades sphingosine-1-phosphate (S1P), thereby, generating ethanolamine. S1P production and secretion is associated with an increased capability of migration and invasion of cancer cells.
  
  
  CONCLUSIONS
  From these results can be concluded that the tumor promoting effect of high concentrations of genistein in immature osteosarcoma cells is reduced by the co-administration of calcitriol, primarily by the breakdown of S1P. It should be tested whether this anti-metastatic pathway can be stimulated by combined treatment also in metastatic xenograft mice models.
authors.affiliation: Department of Pediatric Surgery, University Hospital Marburg, Baldingerstraße, Marburg, Germany.|Department of Cell Biology, Rostock University Medical Center, Schillingallee, Rostock, Germany.
authors.forename: Nadja
authors.initials: N
authors.lastname: Engel
authors.affiliation: Department of Pediatric Surgery, University Hospital Marburg, Baldingerstraße, Marburg, Germany.|Department of Cell Biology, Rostock University Medical Center, Schillingallee, Rostock, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Adamus
authors.affiliation: Metabolomic Discoveries GmbH, Am Mühlenberg, Potsdam-Golm, Germany.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Schauer
authors.affiliation: Department of Cell Biology, Rostock University Medical Center, Schillingallee, Rostock, Germany.
authors.forename: Juliane
authors.initials: J
authors.lastname: Kühn
authors.affiliation: Department of Cell Biology, Rostock University Medical Center, Schillingallee, Rostock, Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Nebe
authors.affiliation: Department of Pediatric Surgery, University Hospital Marburg, Baldingerstraße, Marburg, Germany.
authors.forename: Guido
authors.initials: G
authors.lastname: Seitz
authors.affiliation: Complementary Medicine, Center of Internal Medicine, Rostock University Medical Center, Ernst-Heydemann-Straße 6, Rostock, Germany.
authors.forename: Karin
authors.initials: K
authors.lastname: Kraft
mesh_terms: D000446:Aldehyde-Lyases / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D002117:Calcitriol / Q000008:administration & dosage*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004357:Drug Synergism; D047629:Estrogen Receptor beta / Q000096:biosynthesis* / Q000235:genetics; D019856:Ethanolamine / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D019833:Genistein / Q000008:administration & dosage*; D006801:Humans; D008246:Lysophospholipids / Q000378:metabolism; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism; D012516:Osteosarcoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D048789:Phytoestrogens / Q000008:administration & dosage; D018167:Receptors, Calcitriol / Q000096:biosynthesis* / Q000235:genetics; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D047629:Estrogen Receptor beta; D008246:Lysophospholipids; D048789:Phytoestrogens; D018167:Receptors, Calcitriol; C579457:VDR protein, human; C060506:sphingosine 1-phosphate; D019856:Ethanolamine; D019833:Genistein; D000446:Aldehyde-Lyases; C022649:sphingosine 1-phosphate lyase (aldolase); D002117:Calcitriol; D013110:Sphingosine