Cerebrospinal Fluid Proteomic Analysis Reveals Dysregulation of Methionine Aminopeptidase-2 Expression in Human and Mouse Neurofibromatosis 1–Associated Glioma

Abstract

Individuals affected with the neurofibromatosis 1 (NF1) tumor predisposition syndrome are prone to the development of multiple nervous system tumors, including optic pathway gliomas (OPG). The NF1 tumor suppressor gene product, neurofibromin, functions as a Ras GTPase-activating protein, and has been proposed to regulate cell growth by inhibiting Ras activity. Recent studies from our laboratory have shown that neurofibromin also regulates the mammalian target of rapamycin activity in a Ras-dependent fashion, and that the rapamycin-mediated mammalian target of rapamycin inhibition ameliorates the Nf1À/À astrocyte growth advantage. Moreover, Nf1-deficient astrocytes exhibit increased protein translation. As part of a larger effort to identify protein markers for NF1-associated astrocytomas that could be exploited for therapeutic drug design, we did an objective proteomic analysis of the cerebrospinal fluid from genetically engineered Nf1 mice with optic glioma. One of the proteins found to be increased in the cerebrospinal fluid of OPGbearing mice was the eukaryotic initiation factor-2A binding protein, methionine aminopeptidase 2 (MetAP2). In this study, we show that Nf1 mouse OPGs and NF1-associated human astrocytic tumors, but not sporadic pilocytic or other lowgrade astrocytomas, specifically expressed high levels of MetAP2. In addition, we show that Nf1-deficient astrocytes overexpress MetAP2 in vitro and in vivo, and that treatment with the MetAP2 inhibitor fumagillin significantly reduces Nf1À/À astrocyte proliferation in vitro. These observations suggest that MetAP2 is regulated by neurofibromin, and that MetAP2 inhibitors could be potentially employed to treat NF1-associated tumor proliferation. (Cancer Res 2005; 65(21): 9843-50)

Cotranslational Proteolysis Dominates Glutathione Homeostasis to Support Proper Growth and Development

“…The NME machinery of higher eukaryotes involves two classes of proteases: peptide deformylases and Met aminopeptidase (MAP; with MAP1D enzymes in the organelles and MAP1A and MAP2 in the cytoplasm) Meinnel et al, 2006). There is evidence that NME is tightly regulated throughout development, tumorigenesis, and during the responses induced by various external signals in both animals and plants (Wang et al, 2000;Cleary et al, 2002;Endo et al, 2002;Florens et al, 2002;Kanno et al, 2002;Selvakumar et al, 2004;Dasgupta et al, 2005;Ross et al, 2005;Selvakumar et al, 2006), corroborating the idea that this mechanism is an important signal to support growth, proliferation, survival, and differentiation. Accordingly, NME enzymes are the targets of various natural compounds with antibiotic, antiparasitic, antifungal, or anticancer effects (for reviews, see Boularot et al, 2004;Giglione et al, 2004).…”

Identification of a metastasis signature and the DLX4 homeobox protein as a regulator of metastasis by combined transcriptome approach

“…Twenty-seven genes were overexpressed, whereas 18 were significantly reduced in association with the acquisition of a metastatic capability during in vivo selection of LNM35 (Table 1). The 27 examples overexpressed in LNM35 included various genes previously suggested to play a functional role in metastasis such as chemokine (C-X-C motif) ligand (Heaney et al, 2000;Bernal et al, 2002), immediate early response 3 (IER3) (Goswami et al, 2004;Nicholson et al, 2004), defender against cell death 1 (DAD1) (Ayala et al, 2004;Goswami et al, 2004;Kim et al, 2006) and methionyl aminopeptidase 2 (METAP2) (Dasgupta et al, 2005;Morowitz et al, 2005). Similarly, genes with higher expression in N15 also included some previously implicated in metastasis such as cadherin 1 (E-cadherin) (Cavallaro and Christofori, 2004) and lectin galactoside-binding soluble 3 (galectin-3) (Liu and Rabinovich, 2005).…”

Preclinical Cancer Therapy in a Mouse Model of Neurofibromatosis-1 Optic Glioma

“…Although the Nf1+/À GFAP CKO optic glioma model has been useful for defining the molecular and cellular pathogenesis of NF1 optic glioma formation and growth (24)(25)(26)(27), its value in preclinical therapeutics has been largely unexplored (16). The objective of this study was to compare the three genetically engineered mouse (GEM) optic glioma strains and to select the most appropriate one for preclinical trials evaluating both conventional and biologically targeted therapies.…”