title: Resistance to hypoxia-induced, BNIP3-mediated cell death contributes to an increase in a CD133-positive cell population in human glioblastomas in vitro.
abstract: In addition to intrinsic regulatory mechanisms, brain tumor stemlike cells (BTSCs), a small subpopulation of malignant glial tumor-derived cells, are influenced by environmental factors. Previous reports showed that lowering oxygen tension induced an increase of BTSCs expressing CD133 and other stem cell-related genes and more pronounced clonogenic capacity in vitro. We investigated the mechanisms responsible for hypoxia-dependent induction of CD133-positive BTSCs in glioblastomas. We confirmed that cultures exposed to lowered oxygen levels showed a severalfold increase of CD133-positive BTSCs. Both the increase of CD133-positive cells and deceleration of the growth kinetics were reversible after transfer to normoxic conditions. Exposure to hypoxia induced BNIP3 (BCL2/adenovirus E1B 19-kDa protein-interacting protein 3)-dependent apoptosis preferentially in CD133-negative cells. In contrast, CD133-positive cells proved to be more resistant to hypoxia-induced programmed cell death. Application of the demethylating agent 5'-azacitidine resulted in an increase of BNIP3 expression levels in CD133-positive cells. Thus, epigenetic modifications led to their better survival in lowered oxygen tension. Moreover, the, hypoxia-induced increase of CD133-positive cells was inhibited after 5'-azacitidine treatment. These results suggest the possible efficacy of a novel therapy for glioblastoma focused on eradication of BTSCs by modifications of epigenetic regulation of gene expression.
authors.affiliation: Division of Stereotactic Neurosurgery, University Freiburg Medical Center, Freiburg, Germany.
authors.forename: Ulf Dietrich
authors.initials: UD
authors.lastname: Kahlert
authors.forename: Donata
authors.initials: D
authors.lastname: Maciaczyk
authors.forename: Fangping
authors.initials: F
authors.lastname: Dai
authors.forename: Rainer
authors.initials: R
authors.lastname: Claus
authors.forename: Elke
authors.initials: E
authors.lastname: Firat
authors.forename: Soroush
authors.initials: S
authors.lastname: Doostkam
authors.forename: Tomasz
authors.initials: T
authors.lastname: Bogiel
authors.forename: Maria Stella
authors.initials: MS
authors.lastname: Carro
authors.forename: Mate
authors.initials: M
authors.lastname: Döbrössy
authors.forename: Christel
authors.initials: C
authors.lastname: Herold-Mende
authors.forename: Gabriele
authors.initials: G
authors.lastname: Niedermann
authors.forename: Marco
authors.initials: M
authors.lastname: Prinz
authors.forename: Guido
authors.initials: G
authors.lastname: Nikkhah
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Maciaczyk
mesh_terms: D000071916:AC133 Antigen; D015703:Antigens, CD / Q000378:metabolism*; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001374:Azacitidine / Q000494:pharmacology; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology*; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D047369:Chromatin Immunoprecipitation / Q000379:methods; D019175:DNA Methylation; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005909:Glioblastoma / Q000378:metabolism / Q000473:pathology*; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D000964:Antimetabolites, Antineoplastic; C090121:BNIP3 protein, human; D006023:Glycoproteins; D008565:Membrane Proteins; C000606023:PROM1 protein, human; D010455:Peptides; D011518:Proto-Oncogene Proteins; D001374:Azacitidine