title: A constitutively active form of neurokinin 1 receptor and neurokinin 1 receptor-mediated apoptosis in glioblastomas.
abstract: Previous studies have shown that neurokinin 1 receptor (NK1R) occurs naturally in human glioblastomas and its stimulation causes cell proliferation. In the present study we show that stimulation of NK1R in human U373 glioblastoma cells by substance P increases Akt phosphorylation by 2.5-fold, with an EC(50) of 57 nM. Blockade of NK1R lowers basal phosphorylation of Akt, indicating the presence of a constitutively active form of NK1R; similar results are seen in U251 MG and DBTRG-05 glioblastoma cells. Linkage of NK1R to Akt implicates NK1R in apoptosis of glioblastoma cells. Indeed, treatment of serum-starved U373 cells with substance P reduces apoptosis by 53 +/- 1% (p < 0.05), and treatment with NK1R antagonist L-733,060 increases apoptosis by 64 +/- 16% (p < 0.01). Further, the blockade of NK1R in human glioblastoma cells with L-733,060 causes cleavage of Caspase-3 and proteolysis of poly (ADP-ribose) polymerase. Experiments designed to elucidate the mechanism of NK1R-mediated Akt phosphorylation revealed total involvement of non-receptor tyrosine kinase Src and phosphatidyl-3-kinase, a partial involvement of epidermal growth factor receptor, and no involvement of mitogen-activated protein/extracellular signal-related kinase. Taken together, the results of the present study indicate a key role for NK1R in glioblastoma apoptosis.
authors.affiliation: Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Toshimasa
authors.initials: T
authors.lastname: Akazawa
authors.forename: Shawn G
authors.initials: SG
authors.lastname: Kwatra
authors.forename: Laura E
authors.initials: LE
authors.lastname: Goldsmith
authors.forename: Mark D
authors.initials: MD
authors.lastname: Richardson
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Cox
authors.forename: John H
authors.initials: JH
authors.lastname: Sampson
authors.forename: Madan M
authors.initials: MM
authors.lastname: Kwatra
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001932:Brain Neoplasms / Q000473:pathology*; D045744:Cell Line, Tumor; D017077:Culture Media, Conditioned / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D005909:Glioblastoma / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D064729:Neurokinin-1 Receptor Antagonists; D051058:Oncogene Protein v-akt / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D018040:Receptors, Neurokinin-1 / Q000378:metabolism* / Q000502:physiology*; D013373:Substance P / Q000032:analysis / Q000494:pharmacology
chemical_list: D017077:Culture Media, Conditioned; D064729:Neurokinin-1 Receptor Antagonists; D018040:Receptors, Neurokinin-1; D013373:Substance P; D051058:Oncogene Protein v-akt; D051057:Proto-Oncogene Proteins c-akt