title: Hypoxia enhances the antiglioma cytotoxicity of B10, a glycosylated derivative of betulinic acid.
abstract: B10 is a glycosylated derivative of betulinic acid with promising activity against glioma cells. Lysosomal cell death pathways appear to be essential for its cytotoxicity. We investigated the influence of hypoxia, nutrient deprivation and current standard therapies on B10 cytotoxicity. The human glioma cell lines LN-308 and LNT-229 were exposed to B10 alone or together with irradiation, temozolomide, nutrient deprivation or hypoxia. Cell growth and viability were evaluated by crystal violet staining, clonogenicity assays, propidium iodide uptake and LDH release assays. Cell death was examined using an inhibitor of lysosomal acidification (bafilomycin A1), a cathepsin inhibitor (CA074-Me) and a short-hairpin RNA targeting cathepsin B. Hypoxia substantially enhanced B10-induced cell death. This effect was sensitive to bafilomycin A1 and thus dependent on hypoxia-induced lysosomal acidification. Cathepsin B appeared to mediate cell death because either the inhibitor CA074-Me or cathepsin B gene silencing rescued glioma cells from B10 toxicity under hypoxia. B10 is a novel antitumor agent with substantially enhanced cytotoxicity under hypoxia conferred by increased lysosomal cell death pathway activation. Given the importance of hypoxia for therapy resistance, malignant progression, and as a result of antiangiogenic therapies, B10 might be a promising strategy for hypoxic tumors like malignant glioma.
authors.affiliation: Dr. Senckenberg Institute of Neurooncology, University Hospital Frankfurt, Goethe University, Frankfurt, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fischer
authors.affiliation: Dr. Senckenberg Institute of Neurooncology, University Hospital Frankfurt, Goethe University, Frankfurt, Germany.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Ronellenfitsch
authors.affiliation: Dr. Senckenberg Institute of Neurooncology, University Hospital Frankfurt, Goethe University, Frankfurt, Germany.
authors.forename: Anna-Luisa
authors.initials: AL
authors.lastname: Thiepold
authors.affiliation: Institute of Neurology (Edinger-Institute), University Hospital Frankfurt, Goethe University, Frankfurt, Germany.
authors.forename: Patrick N
authors.initials: PN
authors.lastname: Harter
authors.affiliation: Department of Radiation Therapy and Oncology, University Hospital Frankfurt, Goethe University, Frankfurt, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Reichert
authors.affiliation: Experimental Neurosurgery, University Hospital Frankfurt, Goethe University, Frankfurt, Germany.
authors.forename: Donat
authors.initials: D
authors.lastname: Kögel
authors.affiliation: Biocenter, Martin Luther University Halle-Wittenberg, Halle, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Paschke
authors.affiliation: Institute of Neurology (Edinger-Institute), University Hospital Frankfurt, Goethe University, Frankfurt, Germany.
authors.forename: Michel
authors.initials: M
authors.lastname: Mittelbronn
authors.affiliation: Department of Neurology, University Hospital Zurich, Zurich, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Weller
authors.affiliation: Dr. Senckenberg Institute of Neurooncology, University Hospital Frankfurt, Goethe University, Frankfurt, Germany.
authors.forename: Joachim P
authors.initials: JP
authors.lastname: Steinbach
authors.affiliation: Institute for Experimental Cancer Research in Pediatrics, Goethe-University, Frankfurt, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Fulda
authors.affiliation: Dr. Senckenberg Institute of Neurooncology, University Hospital Frankfurt, Goethe University, Frankfurt, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Bähr
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D002401:Cathepsin B / Q000037:antagonists & inhibitors / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D015687:Cell Hypoxia / Q000187:drug effects; D045744:Cell Line, Tumor; D003606:Dacarbazine / Q000031:analogs & derivatives / Q000494:pharmacology; D004151:Dipeptides / Q000494:pharmacology; D005910:Glioma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D018942:Macrolides / Q000494:pharmacology; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D053978:Pentacyclic Triterpenes; D000077204:Temozolomide; D014315:Triterpenes / Q000494:pharmacology*; D000094062:Betulinic Acid
chemical_list: D018906:Antineoplastic Agents, Alkylating; D000972:Antineoplastic Agents, Phytogenic; C400541:CA 074 methyl ester; D004151:Dipeptides; D018942:Macrolides; D009363:Neoplasm Proteins; D053978:Pentacyclic Triterpenes; D014315:Triterpenes; D003606:Dacarbazine; C040929:bafilomycin A1; C533912:CTSB protein, human; D002401:Cathepsin B; D000077204:Temozolomide; D000094062:Betulinic Acid
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