icatibant and Glioma

Gliomas are the most common malignant brain tumors in adults. Bradykinin (BK) displays an important role in cancer, although the exact role of kinin receptors in the glioma biology remains unclear. This study investigated the role of kinin B1 and B2 receptors (B1R and B2R) on cell proliferation in human glioblastoma cell lineages. The mRNA expression of B1R and B2R was verified by RT-qPCR, whereas the effects of kinin agonists (des-Arg(9)-BK and BK) were analyzed by cell counting, MTT assay and annexin-V/PI determination. The PI3K/Akt and ERK1/2 signaling activation was assessed by flow cytometry. Our results demonstrated that both human glioblastoma cell lines U-138MG and U-251MG express functional B1R and B2R. The proliferative effects induced by the incubation of des-Arg(9)-BK and BK are likely related to the activation of PI3K/Akt and ERK 1/2 pathways. Moreover, the pre-incubation of the selective PI3Kγ blocker AS252424 markedly prevented kinin-induced AKT phosphorylation. Noteworthy, the selective B1R and B2R antagonists SSR240612 and HOE-140 were able to induce cell death of either lineages, with mixed apoptosis/necrosis characteristics. Taken together, the present results show that activation of B1R and B2R might contribute to glioblastoma progression in vitro. Furthermore, PI3K/Akt and ERK 1/2 signaling may be a target for adjuvant treatment of glioblastoma with a possible impact on tumor proliferation.

Topics: Apoptosis; Blotting, Western; Bradykinin; Bradykinin B1 Receptor Antagonists; Bradykinin B2 Receptor Antagonists; Cell Proliferation; Dioxoles; Flow Cytometry; Glioma; Humans; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Phosphatidylinositol 3-Kinases; Phosphorylation; Proto-Oncogene Proteins c-akt; Real-Time Polymerase Chain Reaction; Receptor, Bradykinin B1; Receptor, Bradykinin B2; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sulfonamides; Tumor Cells, Cultured

Confocal fluorescence microscopy was used to study the bradykinin-induced calcium signals in the neuroblastoma x glioma cell line NG 108-15. We found that bradykinin induced a rise in free calcium, not only in the cytoplasm but also in the nucleus. The nuclear and cytosolic calcium concentrations were not significantly different and rose to about 1.2 microM. The signal was mediated by the B2-receptor subtype as confirmed using the specific antagonist Hoe 140. Both the onset and the intensity of the calcium signals were concentration-dependent. The rise of nuclear calcium level was independent of extracellular calcium and suppressed by thapsigargin which is known to deplete inositol 1,4,5-trisphosphate-sensitive calcium stores. Bradykinin-induced calcium increase desensitizes rapidly. This desensitization was shown not to involve activation of protein kinase C.

Topics: Animals; Bradykinin; Calcium; Cell Nucleus; Fura-2; Glioma; Hybrid Cells; Inositol 1,4,5-Trisphosphate; Microscopy, Confocal; Neuroblastoma; Protein Kinase C; Rats; Signal Transduction; Tumor Cells, Cultured

A capillary electrophoresis system with single-cell biosensors as a detector has been used to separate and identify ligands in complex biological samples. The power of this procedure was significantly increased by introducing antagonists that inhibited the cellular response from selected ligand-receptor interactions. The single-cell biosensor was based on the ligand-receptor binding and G-protein-mediated signal transduction pathways in PC12 and NG108-15 cell lines. Receptor activation was measured as increases in cytosolic free calcium ion concentration by using fluorescence microscopy with the intracellular calcium ion indicator fluo-3-acetoxymethyl ester. Specifically, a mixture of bradykinin (BK) and acetylcholine (ACh) was fractionated and the components were identified by inhibiting the cellular response with icatibant (HOE 140), a selective antagonist to the BK B2 receptor subtype (B2BK), and atropine, an antagonist to muscarinic ACh receptor subtypes. Structurally related forms of BK were also identified based on inhibiting B2BK receptors. Applications of this technique include identification of endogenous BK in a lysate of human hepatocellular carcinoma cells (Hep G2) and screening for bioactivity of BK degradation products in human blood plasma. The data demonstrate that the use of antagonists with a single-cell biosensor separation system aids identification of separated components and receptor subtypes.

Topics: Animals; Atropine; Bradykinin; Bradykinin Receptor Antagonists; Capillary Action; Carcinoma, Hepatocellular; Cell Line; Electrophoresis; Glioma; Humans; Ligands; Liver Neoplasms; Mice; Muscarinic Antagonists; Neuroblastoma; PC12 Cells; Rats; Receptors, Bradykinin; Receptors, Muscarinic; Tumor Cells, Cultured