title: Enhancement of Fas-ligand-mediated programmed cell death by taurolidine.
abstract: BACKGROUND
  Taurolidine was recently found to have a direct and selective antineoplastic effect on brain tumor cells. The ability of taurolidine to exert antineoplastic action by enhancement of Fas-mediated apoptosis in different malignant glioma cell lines was investigated.
  
  
  METHODS
  Human derived U373 cells were cultured and incubated with taurolidine and the median inhibitory concentration (IC50) was calculated. Flow cytometric analysis was performed to assess changes in DNA content. The cells were qualitatively and quantitatively examined using light microscopy and electron microscopy. LN-18 and LN-229 cells were incubated in the absence or presence of either Fas-ligand, taurolidine or respective combinations thereof. The cell viability was determined by adding a double concentrated WST-1 reagent. The activity of the mitochondrial succinate reductase was measured in an ELISA reader.
  
  
  RESULTS
  The exposure of U373 cells to taurolidine led to a concentration-dependent (IC50 35.8 +/- 2.2 micrograms/ml) loss of cell viability. Flow cytometric analysis demonstrated a concentration-dependent appearance of DNA debris in the sub-Go/G1 region. In the presence of 6.25 vol.% Fas-ligand, LN-18 cells displayed more than 90% loss of cell viability, whereas the viability of LN-229 cells was reduced only at higher concentrations of Fas-ligand. Taurolidine by itself did not appreciably affect the viability of LN-18 cells in the investigated concentration range, but was able to enhance the effect of Fasligand on LN-18 cells. The exposure of LN-229 cells to taurolidine alone caused an appreciable loss of cell viability by about 70% at the highest concentration tested. Cell destruction by Fas-ligand (10 vol.%) was enhanced in the presence of taurolidine.
  
  
  CONCLUSIONS
  The antineoplastic activity of taurolidine seems to be partially based on the enhancement of Fas-ligand-induced apoptosis. In addition, taurolidine was demonstrated to have an antieoplastic effect independent of Fas-ligand. Perhaps taurolidine exerts antineoplastic activity based on different mechanisms.
authors.affiliation: Department of Neurosurgery, Benjamin Franklin Medical Center, Free University of Berlin Hindenburgdamm 30, 12203 Berlin, Germany. r.stendel@web.de
authors.forename: Ruediger
authors.initials: R
authors.lastname: Stendel
authors.forename: Louis
authors.initials: L
authors.lastname: Scheurer
authors.forename: Gisela
authors.initials: G
authors.lastname: Stoltenburg-Didinger
authors.forename: Mario
authors.initials: M
authors.lastname: Brock
authors.forename: Hanns
authors.initials: H
authors.lastname: Möhler
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D001254:Astrocytoma / Q000188:drug therapy / Q000473:pathology; D002470:Cell Survival / Q000187:drug effects*; D053222:Fas Ligand Protein; D005434:Flow Cytometry; D005909:Glioblastoma / Q000188:drug therapy / Q000473:pathology; D006801:Humans; D008562:Membrane Glycoproteins / Q000502:physiology*; D013654:Taurine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D013829:Thiadiazines / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D013829:Thiadiazines; D013654:Taurine; C012566:taurolidine