sirolimus and Meningioma

Meningioma represents the most common primary brain tumor in adults. Recently several non-NF2 mutations in meningioma have been identified and correlated with certain pathological subtypes, locations and clinical observations. Alterations of cellular pathways due to these mutations, however, have largely remained elusive. Here we report that the Krueppel like factor 4 (KLF4)-K409Q mutation in skull base meningiomas triggers a distinct tumor phenotype. Transcriptomic analysis of 17 meningioma samples revealed that KLF4

Topics: Animals; Cell Line, Tumor; Cell Proliferation; Gene Expression Regulation, Neoplastic; Humans; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Kruppel-Like Factor 4; Kruppel-Like Transcription Factors; Mechanistic Target of Rapamycin Complex 1; Meningeal Neoplasms; Meningioma; Mice; Mice, Nude; Mutation; Neoplasm Transplantation; Prolyl Hydroxylases; Protein Kinase Inhibitors; Reverse Transcriptase Polymerase Chain Reaction; RNA-Seq; Signal Transduction; Sirolimus; Skull Base Neoplasms; Tumor Hypoxia; Up-Regulation

Pituitary adenoma and meningioma are the most common benign tumors in the central nervous system. Pituitary adenoma associated with meningioma (PAM) is a rare disease and the clinical features and mechanisms of PAM are unclear.. We summarized the clinical data of 57 PAM patients and compared with sporadic pituitary adenoma (SPA) and sporadic meningioma (SM). 5 pituitary adenomas of PAM and 5 SPAs were performed ceRNA microarray. qRT-PCR, Western Blot, siMEN1 and rapamycin inhibition experiment were validated for ceRNA microarray.. Clinical variable analyses revealed that significant correlations between PAM and female sex as well as older age when compared with SPA and significant correlations between PAM and transitional meningioma as well as older age when compared with SM. Additionally, the characteristics of PAM were significantly different for MEN1 patients. Functional experiments showed lower expression of MEN1 can upregulate mTOR signaling, in accordance with the result of ceRNA microarray. Rapamycin treatment promotes apoptosis in primary pituitary adenoma and meningioma cells of PAM.. MEN1 plays an important role in PAM by upregulating mTOR signaling pathway. Rapamycin represents a potential therapeutic strategy for PAM in the future.

Topics: Adenoma; Adult; Aged; Apoptosis; Female; Humans; Male; Meningeal Neoplasms; Meningioma; Metabolic Networks and Pathways; Middle Aged; Neoplasms, Multiple Primary; Oligonucleotide Array Sequence Analysis; Pituitary Neoplasms; Proto-Oncogene Proteins; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Translational Research, Biomedical; Tumor Cells, Cultured; Young Adult

To evaluate the mTORC1 (mammalian target of rapamycin complex 1) pathway in meningiomas and to explore mTORC1 as a therapeutic target in meningioma cell lines and mouse models.. Tissue microarrays (53 meningiomas of all WHO grades) were stained for phosphorylated polypeptides of mTOR, Akt, and the mTORC1 targets 4EBP1 and p70S6K, the latter being the consensus marker for mTORC1 activity. Expression of proteins and mRNAs was assessed by Western blotting and real-time PCR in 25 tumors. Cell lines Ben-Men-1 (benign), IOMM-Lee and KT21 (malignant), and pairs of merlin-positive or -negative meningioma cells were used to assess sensitivity toward mTORC1 inhibitors in methyl-tetrazolium and bromodeoxyuridine (BrdUrd) assays. The effect of temsirolimus (20 mg/kg daily) on tumor weight or MRI-estimated tumor volume was tested by treatment of eight nude mice (vs. 7 controls) carrying subcutaneous IOMM-Lee xenografts, or of eight (5) mice xenotransplanted intracranially with IOMM-Lee (KT21) cells in comparison to eight (5) untreated controls.. All components of the mTORC1 pathway were expressed and activated in meningiomas, independent of their WHO grade. A significant dosage-dependent growth inhibition by temsirolimus and everolimus was observed in all cell lines. It was slightly diminished by merlin loss. In the orthotopic and subcutaneous xenograft models, temsirolimus treatment resulted in about 70% growth reduction of tumors (P < 0.01), which was paralleled by reduction of Ki67 mitotic index (P < 0.05) and reduction of mTORC1 activity (p70S6K phosphorylation) within the tumors.. mTORC1 inhibitors suppress meningioma growth in mouse models, although the present study did not measure survival.

Topics: Animals; Apoptosis; Blotting, Western; Cell Adhesion; Cell Proliferation; Disease Models, Animal; Genes, Neurofibromatosis 2; Humans; Immunoenzyme Techniques; Male; Mechanistic Target of Rapamycin Complex 1; Meningeal Neoplasms; Meningioma; Mice; Mice, Nude; Multiprotein Complexes; Neoplasm Grading; Protein Kinase Inhibitors; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sirolimus; TOR Serine-Threonine Kinases; Tumor Cells, Cultured

Inactivating mutations in the neurofibromatosis 2 (NF2) tumor suppressor gene results in the development of schwannomas and meningiomas. Using NF2-deficient meningioma cells and tumors, together with the normal cellular counterparts that meningiomas derive, arachnoid cells, we identified merlin as a novel negative regulator of mTOR complex 1 (mTORC1). We now show that merlin positively regulates the kinase activity of mTORC2, a second functionally distinct mTOR complex, and that downstream phosphorylation of mTORC2 substrates, including Akt, is reduced upon acute merlin deficiency in cells. In response to general growth factor stimulation, Akt signaling is attenuated in merlin RNA interference-suppressed human arachnoid and Schwann cells by mechanisms mediated by hyperactive mTORC1 and impaired mTORC2. Moreover, Akt signaling is impaired differentially in a cell type-dependent manner in response to distinct growth factor stimuli. However, contrary to activation of mTORC1, the attenuated mTORC2 signaling profiles exhibited by normal arachnoid and Schwann cells in response to acute merlin loss were not consistently reflected in NF2-deficient meningiomas and schwannomas, suggesting additional genetic events may have been acquired in tumors after initial merlin loss. This finding contrasts with another benign tumor disorder, tuberous sclerosis complex, which exhibits attenuated mTORC2 signaling profiles in both cells and tumors. Finally, we examined rapamycin, as well as the mTOR kinase inhibitor, Torin1, targeting both mTOR complexes to identify the most efficacious class of compounds for blocking mTOR-mediated signaling and proliferation in merlin-deficient meningioma cells. These studies may ultimately aid in the development of suitable therapeutics for NF2-associated tumors.

Topics: Cell Line, Tumor; Gene Expression Regulation, Neoplastic; Humans; Mechanistic Target of Rapamycin Complex 1; Meningeal Neoplasms; Meningioma; Multiprotein Complexes; Naphthyridines; Neurilemmoma; Neurofibromin 2; Oncogene Protein v-akt; Proteins; RNA Interference; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Transcription Factors; Tuberous Sclerosis

Inactivating mutations of the neurofibromatosis 2 (NF2) gene, NF2, result predominantly in benign neurological tumors, schwannomas and meningiomas, in humans; however, mutations in murine Nf2 lead to a broad spectrum of cancerous tumors. The tumor-suppressive function of the NF2 protein, merlin, a membrane-cytoskeleton linker, remains unclear. Here, we identify the mammalian target of rapamycin complex 1 (mTORC1) as a novel mediator of merlin's tumor suppressor activity. Merlin-deficient human meningioma cells and merlin knockdown arachnoidal cells, the nonneoplastic cell counterparts of meningiomas, exhibit rapamycin-sensitive constitutive mTORC1 activation and increased growth. NF2 patient tumors and Nf2-deficient mouse embryonic fibroblasts demonstrate elevated mTORC1 signaling. Conversely, the exogenous expression of wild-type merlin isoforms, but not a patient-derived L64P mutant, suppresses mTORC1 signaling. Merlin does not regulate mTORC1 via the established mechanism of phosphoinositide 3-kinase-Akt or mitogen-activated protein kinase/extracellular signal-regulated kinase-mediated TSC2 inactivation and may instead regulate TSC/mTOR signaling in a novel fashion. In conclusion, the deregulation of mTORC1 activation underlies the aberrant growth and proliferation of NF2-associated tumors and may restrain the growth of these lesions through negative feedback mechanisms, suggesting that rapamycin in combination with phosphoinositide 3-kinase inhibitors may be therapeutic for NF2.

Topics: Animals; Antibiotics, Antineoplastic; Arachnoid; Cell Cycle; Cell Line; Cell Proliferation; Cells, Cultured; Fibroblasts; Flow Cytometry; Humans; Immunoblotting; Mechanistic Target of Rapamycin Complex 1; Meningioma; Mice; Mice, Knockout; Multiprotein Complexes; Neurilemmoma; Neurofibromin 2; Phosphatidylinositol 3-Kinases; Proteins; Proto-Oncogene Proteins c-akt; RNA, Small Interfering; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Transcription Factors; Transfection; Tumor Cells, Cultured