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  • Dasgupta, Biplab  (2)
  • 2005-2009  (2)
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  • 2005-2009  (2)
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  • 1
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2005
    In:  Cancer Research Vol. 65, No. 21 ( 2005-11-01), p. 9843-9850
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 65, No. 21 ( 2005-11-01), p. 9843-9850
    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 Nf1−/− 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 OPG-bearing mice was the eukaryotic initiation factor-2α 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 low-grade 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 Nf1−/− 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.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2005
    detail.hit.zdb_id: 2036785-5
    detail.hit.zdb_id: 1432-1
    detail.hit.zdb_id: 410466-3
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2005
    In:  Cancer Research Vol. 65, No. 7 ( 2005-04-01), p. 2755-2760
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 65, No. 7 ( 2005-04-01), p. 2755-2760
    Abstract: Individuals with the tumor predisposition syndrome, neurofibromatosis 1 (NF1), are prone to development of nervous system tumors, including neurofibromas and pilocytic astrocytomas. Based on the ability of the NF1 gene product (neurofibromin) to function as a GTPase activating protein for RAS, initial biologically based therapies for NF1-associated tumors focused on the use of RAS inhibitors, but with limited clinical success. In an effort to identify additional targets for therapeutic drug design in NF1, we used an unbiased proteomic approach to uncover unanticipated intracellular signaling pathways dysregulated in Nf1-deficient astrocytes. We found that the expression of proteins involved in promoting ribosome biogenesis was increased in the absence of neurofibromin. In addition, Nf1-deficient astrocytes exhibit high levels of mammalian target of rapamycin (mTOR) pathway activation, which was inhibited by blocking K-RAS or phosphatidylinositol 3-kinase activation. This mTOR pathway hyperactivation was reflected by high levels of ribosomal S6 activation in both Nf1 mutant mouse optic nerve gliomas and in human NF1-associated pilocytic astrocytoma tumors. Moreover, inhibition of mTOR signaling in Nf1−/− astrocytes abrogated their growth advantage in culture, restoring normal proliferative rates. These results suggest that mTOR pathway inhibition may represent a logical and tractable biologically based therapy for brain tumors in NF1.
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2005
    detail.hit.zdb_id: 2036785-5
    detail.hit.zdb_id: 1432-1
    detail.hit.zdb_id: 410466-3
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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