title: Potentiation of temozolomide antitumor effect by purine receptor ligands able to restrain the in vitro growth of human glioblastoma stem cells.
abstract: Glioblastoma multiforme (GBM), the most common and aggressive brain tumor in humans, comprises a population of stem-like cells (GSCs) that are currently investigated as potential target for GBM therapy. Here, we used GSCs isolated from three different GBM surgical specimens to examine the antitumor activity of purines. Cultured GSCs expressed either metabotropic adenosine P1 and ATP P2Y receptors or ionotropic P2X7 receptors. GSC exposure for 48 h to 10-150 μM ATP, P2R ligand, or to ADPβS or MRS2365, P2Y1R agonists, enhanced cell expansion. This effect was counteracted by the PY1R antagonist MRS2500. In contrast, 48-h treatment with higher doses of ATP or UTP, which binds to P2Y2/4R, or 2'(3')-O-(4-benzoylbenzoyl)-ATP (Bz-ATP), P2X7R agonist, decreased GSC proliferation. Such a reduction was due to apoptotic or necrotic cell death but mostly to growth arrest. Accordingly, cell regrowth and secondary neurosphere formation were observed 2 weeks after the end of treatment. Suramin, nonselective P2R antagonist, MRS1220 or AZ11645373, selective A3R or P2X7R antagonists, respectively, counteracted ATP antiproliferative effects. AZ11645373 also abolished the inhibitory effect of Bz-ATP low doses on GSC growth. These findings provide important clues on the anticancer potential of ligands for A3R, P2Y1R, and P2X7R, which are involved in the GSC growth control. Interestingly, ATP and BzATP potentiated the cytotoxicity of temozolomide (TMZ), currently used for GBM therapy, enabling it to cause a greater and long-lasting inhibitory effect on GSC duplication when readded to cells previously treated with purine nucleotides plus TMZ. These are the first findings identifying purine nucleotides as able to enhance TMZ antitumor efficacy and might have an immediate translational impact.
authors.affiliation: Department of Medical, Oral and Biotechnology Sciences, University of Chieti-Pescara, via dei Vestini 29, 66100, Chieti, Italy.
authors.forename: Iolanda
authors.initials: I
authors.lastname: D'Alimonte
authors.forename: Eleonora
authors.initials: E
authors.lastname: Nargi
authors.forename: Mariachiara
authors.initials: M
authors.lastname: Zuccarini
authors.forename: Paola
authors.initials: P
authors.lastname: Lanuti
authors.forename: Patrizia
authors.initials: P
authors.lastname: Di Iorio
authors.forename: Patricia
authors.initials: P
authors.lastname: Giuliani
authors.forename: Lucia
authors.initials: L
authors.lastname: Ricci-Vitiani
authors.forename: Roberto
authors.initials: R
authors.lastname: Pallini
authors.forename: Francesco
authors.initials: F
authors.lastname: Caciagli
authors.forename: Renata
authors.initials: R
authors.lastname: Ciccarelli
mesh_terms: D058918:Adenosine A3 Receptor Antagonists / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D018906:Antineoplastic Agents, Alkylating / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000473:pathology; D061945:Caspase Inhibitors / Q000494:pharmacology; D049109:Cell Proliferation; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004357:Drug Synergism; D005909:Glioblastoma / Q000188:drug therapy* / Q000473:pathology; D006801:Humans; D008024:Ligands; D014411:Neoplastic Stem Cells / Q000187:drug effects*; D058921:Purinergic P2Y Receptor Antagonists / Q000494:pharmacology; D011983:Receptors, Purinergic / Q000187:drug effects*; D018047:Receptors, Purinergic P1 / Q000187:drug effects; D058486:Receptors, Purinergic P2X7 / Q000187:drug effects; D000077204:Temozolomide
chemical_list: D058918:Adenosine A3 Receptor Antagonists; D018906:Antineoplastic Agents, Alkylating; D061945:Caspase Inhibitors; D008024:Ligands; D058921:Purinergic P2Y Receptor Antagonists; D011983:Receptors, Purinergic; D018047:Receptors, Purinergic P1; D058486:Receptors, Purinergic P2X7; C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; D003606:Dacarbazine; D000255:Adenosine Triphosphate; D000077204:Temozolomide