title: Neurofibroma-associated growth factors activate a distinct signaling network to alter the function of neurofibromin-deficient endothelial cells.
abstract: Genetic inactivation of tumor suppressor genes initiates human cancers. However, interaction of accessory cells with the tumor-initiating cell within the microenvironment is often required for tumor progression. This paradigm is relevant to understanding neurofibroma development in neurofibromatosis type I patients. Somatic inactivation of the Nf1 tumor suppressor gene, which encodes neurofibromin, is necessary but not sufficient to initiate neurofibroma development. In contrast, neurofibromas occur with high penetrance in mice in which Nf1 is ablated in Schwann cells in the context of a heterozygous mutant (Nf1+/-) microenvironment. Neurofibromas are highly vascularized, and recent studies suggest that Nf1+/- mice have increased angiogenesis in vivo. However, the function of neurofibromin in human endothelial cells (ECs) and the biochemical mechanism by which neurofibromin regulates neoangiogenesis are not known. Utilizing Nf1+/- mice, primary human ECs and endothelial progenitor cells harvested from NF1 patients, we identified a discrete Ras effector pathway, which alters the proliferation and migration of neurofibromin-deficient ECs in response to neurofibroma-derived growth factors both in vitro and in vivo. Thus, these studies identify a unique biochemical pathway in Nf1+/- ECs as a potential therapeutic target in the neurofibroma microenvironment.
authors.affiliation: Department of Pediatrics, Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, 1044 W. Walnut Street, Indianapolis, IN 46202, USA.
authors.forename: Amy M
authors.initials: AM
authors.lastname: Munchhof
authors.forename: Fang
authors.initials: F
authors.lastname: Li
authors.forename: Hilary A
authors.initials: HA
authors.lastname: White
authors.forename: Laura E
authors.initials: LE
authors.lastname: Mead
authors.forename: Theresa R
authors.initials: TR
authors.lastname: Krier
authors.forename: Amy
authors.initials: A
authors.lastname: Fenoglio
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Li
authors.forename: Jin
authors.initials: J
authors.lastname: Yuan
authors.forename: Feng-Chun
authors.initials: FC
authors.lastname: Yang
authors.forename: David A
authors.initials: DA
authors.lastname: Ingram
mesh_terms: D000483:Alleles; D000818:Animals; D003094:Collagen / Q000737:chemistry; D004338:Drug Combinations; D004730:Endothelium, Vascular / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006133:Growth Substances / Q000378:metabolism; D006801:Humans; D007797:Laminin / Q000737:chemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009455:Neurofibroma / Q000473:pathology*; D025542:Neurofibromin 1 / Q000235:genetics* / Q000502:physiology; D011509:Proteoglycans / Q000737:chemistry; D012583:Schwann Cells / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D004338:Drug Combinations; D006133:Growth Substances; D007797:Laminin; D025542:Neurofibromin 1; D011509:Proteoglycans; C059485:matrigel; D003094:Collagen; D048049:Extracellular Signal-Regulated MAP Kinases