kallidin and Glioma

Treatment of malignant glioma with chemotherapy is limited mostly because of delivery impediment related to the blood-brain tumor barrier (BTB). B1 receptors (B1R), inducible prototypical G-protein coupled receptors (GPCR) can regulate permeability of vessels including possibly that of brain tumors. Here, we determine the extent of BTB permeability induced by the natural and synthetic peptide B1R agonists, LysdesArg(9)BK (LDBK) and SarLys[dPhe(8)]desArg(9)BK (NG29), in syngeneic F98 glioma-implanted Fischer rats. Ten days after tumor inoculation, we detected the presence of B1R on tumor cells and associated vasculature. NG29 infusion increased brain distribution volume and uptake profiles of paramagnetic probes (Magnevist and Gadomer) at tumoral sites (T(1)-weighted imaging). These effects were blocked by B1R antagonist and non-selective cyclooxygenase inhibitors, but not by B2R antagonist and non-selective nitric oxide synthase inhibitors. Consistent with MRI data, systemic co-administration of NG29 improved brain tumor delivery of Carboplatin chemotherapy (ICP-Mass spectrometry). We also detected elevated B1R expression in clinical samples of high-grade glioma. Our results documented a novel GPCR-signaling mechanism for promoting transient BTB disruption, involving activation of B1R and ensuing production of COX metabolites. They also underlined the potential value of synthetic biostable B1R agonists as selective BTB modulators for local delivery of different sized-therapeutics at (peri)tumoral sites.

Topics: Adult; Aged; Animals; Biological Transport; Bradykinin; Brain Neoplasms; Capillary Permeability; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Glioma; Humans; Kallidin; Male; Middle Aged; Permeability; Rats; Rats, Inbred F344; Receptor, Bradykinin B1

The peptides bradykinin and kallidin are released in response to noxious stimuli and mediate various physiological effects, including a direct stimulation of nociceptive afferent neurones. The nature of the receptor molecules through which these ligands act is presently unknown. We synthesised an iodinatable photoaffinity probe, N epsilon-4-azidosalicylylkallidin, and used it in an attempt to identify candidate bradykinin receptors on the NG108-15 neuroblastoma X glioma hybrid cell line. The ligand bound in subdued light to a particulate fraction of NG108-15 tumours and could be displaced by bradykinin with an IC50 of 0.33 nM. In a physiological assay, it behaved as an agonist equipotent with bradykinin. Gel analysis of the labelled products after photolysis of the iodinated ligand in the presence of NG108-15 cells or tumour membranes revealed bradykinin-blockable labelling of a glycoprotein with an Mr of 166,000. The probe was also able to label purified commercial angiotensin converting enzyme. The band labelled in NG108-15 cells was immunoprecipitable with a polyclonal antiserum to angiotensin converting enzyme, an enzyme shown to be present in low amounts in these preparations by direct binding using the iodinatable specific ligand MK351A.

Topics: Affinity Labels; Angiotensin-Converting Enzyme Inhibitors; Azides; Bradykinin; Calcium; Dipeptides; Electrophoresis, Polyacrylamide Gel; Glioma; Hybrid Cells; Immunosorbent Techniques; Iodine Radioisotopes; Kallidin; Molecular Structure; Molecular Weight; Neuroblastoma; Peptide Hydrolases; Peptidyl-Dipeptidase A; Photolysis; Receptors, Bradykinin; Receptors, Neurotransmitter; Tumor Cells, Cultured

Topics: Affinity Labels; Amino Acid Sequence; Animals; Azides; Binding, Competitive; Bradykinin; Cell Line; Glioma; Hybrid Cells; Kallidin; Kinetics; Molecular Sequence Data; Neuroblastoma; Peptidyl-Dipeptidase A; Receptors, Bradykinin; Receptors, Neurotransmitter