Necrosis Induction in Glioblastoma Cells Reveals a New “Bioswitch” Function for the MT1-MMP/G6PT Signaling Axis in proMMP-2 Activation versus Cell Death Decision

Belkaid, Anissa; Fortier, Simon; Cao, Jian; Annabi, Borhane

doi:10.1593/neo.07142

Cited by 44 publications

(44 citation statements)

References 52 publications

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“…This is in accordance with a recent study showing that MT1-MMP may have an additional role in regulating glioma cell homeostasis and that increased MT1-MMP expression can induce necrosis in glioma (16). Such a specific signal transduction role is also suggested by our experiments, as the death promoting effect of MT1-MMP in glioma was species-specific and could not be mimicked by heterologous MT1-MMP expression.…”

Section: Glioma Depend On Mt1-mmp Expressing Microglia To Promote Tumorsupporting

confidence: 93%

Gliomas induce and exploit microglial MT1-MMP expression for tumor expansion

Marković

Vinnakota

Chirasani

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

341

328

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for highly malignant gliomas (World Health Organization grade III and IV) there is no successful treatment; patients have an average survival time of approximately 1 y after diagnosis. Glioma cells are highly invasive and infiltrate normal brain tissue, and as a result, surgical resection is always incomplete. Degradation of ECM by membrane-bound and secreted metalloproteases facilitates glioma invasion. In particular, the membrane-bound metalloproteases are pivotal for tumor invasion as they very efficiently digest extracellular matrix proteins and also activate secreted metalloproteases (1) like matrix metalloproteinase-2 (MMP-2, also known as gelatinase A), which is one of the major proteases involved in glioma invasion in mouse models (2) and probably also in humans (3). Hence, membrane-inserted metalloproteases like membrane type 1 matrix metalloproteinase (MT1-MMP) can enable gliomas to invade the brain parenchyma as single cells (4).Microglia are the intrinsic immune cells of the brain; they control the innate and the adaptive immune response in the CNS and are activated by inflammatory or other pathological stimuli (5). Activation of microglial toll-like receptors (TLRs) triggers the innate immune response and can initiate host-defense and tissue repair mechanisms, but also CNS inflammation, neurodegeneration, and trauma (5, 6). As microglial cells are attracted toward glioma in large numbers-glioma tissue consists of as much as 30% microglial cells-and because microglia density in gliomas positively correlates with malignancy, invasiveness, and grading of the tumors (7-9), we investigated if microglia may actively contribute to glioma expansion. Here, we show that soluble factors released from glioma stimulate microglial TLRs, resulting in microglial MT1-MMP expression via the TLR downstream signaling molecules MyD88 and p38 MAPK. In turn, MT1-MMP expression and activity in these immune cells promotes glioma cell invasion and tumor expansion. ResultsGlioma Associated Microglia Over-Express MT1-MMP. We analyzed the expression pattern of the matrix protease MT1-MMP in mouse and human gliomas and found the enzyme to be expressed predominantly in microglial cells closely associated with the tumors. Whereas tumor-free human brain samples showed virtually no MT1-MMP expression, we detected intense MT1-MMP labeling, especially in higher-grade gliomas. Importantly, in human samples, immunolabeling for the microglial marker Iba1 and for MT1-MMP largely overlapped [supporting information (SI) Fig. S1 A-D and Table S1]. Likewise, after injection of a human glioma cell line (U373 cells) into immunodeficient mice, we detected that microglia represent the predominant cell type contributing intratumoral MT1-MMP expression (see Fig. S1E).In our in vivo mouse model, the glioma cells were identified by stable expression of EGFP and microglial cells by immunolabeling for Iba1. In sections obtained from mice 2 weeks after intracerebral injection with isogenic glioma cells (GL261 cells), we found an increased density of mic...

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Section: Glioma Depend On Mt1-mmp Expressing Microglia To Promote Tumorsupporting

confidence: 93%

Gliomas induce and exploit microglial MT1-MMP expression for tumor expansion

Marković

Vinnakota

Chirasani

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

341

328

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“…Effect of 44-MT1 Forms on Pro-MMP-2 Activation-We first examined the effects of 44-MT1 forms on pro-MMP-2 activation, a major function of MT1-MMP (75). Unstimulated parental HT1080 and HT1080-EV cells showed no pro-MMP-2 activation (Fig.…”

Section: Resultsmentioning

confidence: 99%

The Inactive 44-kDa Processed Form of Membrane Type 1 Matrix Metalloproteinase (MT1-MMP) Enhances Proteolytic Activity via Regulation of Endocytosis of Active MT1-MMP

Cho

Osenkowski

Zhao

et al. 2008

Journal of Biological Chemistry

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Membrane type 1 (MT1) matrix metalloproteinase (MMP-14)is a membrane-tethered MMP considered to be a major mediator of pericellular proteolysis. MT1-MMP is regulated by a complex array of mechanisms, including processing and endocytosis that determine the pool of active proteases on the plasma membrane. Autocatalytic processing of active MT1-MMP generates an inactive membrane-tethered 44-kDa product (44-MT1) lacking the catalytic domain. This form preserves all other enzyme domains and is retained at the cell surface. Paradoxically, accumulation of the 44-kDa form has been associated with increased enzymatic activity. Here we report that expression of a recom- Membrane type 1 matrix metalloproteinase (MT1-MMP, 2 MMP-14) is a type I-transmembrane protease and a major mediator of pericellular proteolysis. MT1-MMP is responsible for the proteolytic cleavage of multiple pericellular and membrane-associated substrates, including collagens and other extracellular matrix proteins, growth factors, growth factor receptors, cell adhesion proteins and their receptors, cytokines, protease inhibitors, and proteases, just to mention a few (1-5). MT1-MMP is also the major physiological activator of pro-MMP-2 (pro-gelatinase A) on the cell surface (6, 7), a process that further contributes to pericellular proteolysis. As a multifunctional protease, MT1-MMP elicits profound effects on cell behavior and has been implicated in the pathogenesis of various human diseases, including cancer (8 -10), diabetes (11, 12), vascular (13, 14), and connective tissue diseases (2).The importance of MT1-MMP for pericellular proteolysis demands a tight control of its catalytic activity at the cell surface. This is partly achieved by the action of endogenous protease inhibitors, the tissue inhibitors of metalloproteinases (TIMPs), which bind to the active site inhibiting catalysis (15). In addition, by virtue of being a membrane-anchored protease, MT1-MMP developed a unique set of regulatory mechanisms that control enzymatic activity independently of TIMPs. These processes include the targeting of active enzyme to specific plasma membrane locations, endocytosis, and autocatalytic processing (1, 16 -19). Together, these distinct processes determine the level of active enzyme on the cell surface. However, how these processes are integrated to control the pool of active MT1-MMP is not understood.The processing of MT1-MMP is a cell surface event in which the active enzyme is usually autocatalytically cleaved in trans to generate a major membrane-anchored product of ϳ44 kDa (also referred to as the 43-or 45-kDa species in some studies) and a soluble ϳ18-kDa inactive fragment of the catalytic domain (6, 20 -25). The 44-kDa product of MT1-MMP is detected in cultured cells expressing natural MT1-MMP (20, 26 -32) and has been found in platelets (33), human tumors extracts (34 -36), and extracts of arthritic synovial tissues (37). MT1-MMP processing is stimulated by a variety of factors known to stimulate MT1-MMP expression, trafficking, and/or endocytosi...

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“…Necrotic deaths that rely on microfilament/adhesion changes, as in the case of G5, have been recently observed (40). Necrotic death of lymphocytes, in response to mycophenolic, which involves Rho-GTPase Cdc42 activity and actin polymerization, shares some features with G5.…”

Section: Discussionmentioning

confidence: 99%

Characterization of caspase-dependent and caspase-independent deaths in glioblastoma cells treated with inhibitors of the ubiquitin-proteasome system

Foti

Florean

Pezzutto

et al. 2009

Molecular Cancer Therapeutics

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The regulation of the necrotic death and its relevance in anticancer therapy are largely unknown. Here, we have investigated the proapoptotic and pronecrotic activities of two ubiquitin-proteasome system inhibitors: bortezomib and G5. The present study points out that the glioblastoma cell lines U87MG and T98G are useful models to study the susceptibility to apoptosis and necrosis in response to ubiquitin-proteasome system inhibitors. U87MG cells show resistance to apoptosis induced by bortezomib and G5, but they are more susceptible to necrosis induced by G5. Conversely, T98G cells are more susceptible to apoptosis induced by both inhibitors but show some resistance to G5-induced necrosis. No overt differences in the induction of Noxa and Mcl-1 or in the expression levels of other components of the apoptotic machinery were observed between U87MG and T98G cells. Instead, by comparing the transcriptional profiles of the two cell lines, we have found that the resistance to G5-induced necrosis could arise from differences in glutathione synthesis/utilization and in the microenvironment. In particular, collagen IV, which is highly expressed in T98G cells, and fibronectin, whose adhesive function is counteracted by tenascin-C in U87MG cells, can restrain the necrotic response to G5. Collectively, our results provide an initial characterization of the molecular signals governing cell death by necrosis in glioblastoma cell lines.

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Necrosis Induction in Glioblastoma Cells Reveals a New “Bioswitch” Function for the MT1-MMP/G6PT Signaling Axis in proMMP-2 Activation versus Cell Death Decision

Cited by 44 publications

References 52 publications

Gliomas induce and exploit microglial MT1-MMP expression for tumor expansion

Gliomas induce and exploit microglial MT1-MMP expression for tumor expansion

The Inactive 44-kDa Processed Form of Membrane Type 1 Matrix Metalloproteinase (MT1-MMP) Enhances Proteolytic Activity via Regulation of Endocytosis of Active MT1-MMP

Characterization of caspase-dependent and caspase-independent deaths in glioblastoma cells treated with inhibitors of the ubiquitin-proteasome system

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