LGI1, a Putative Tumor Metastasis Suppressor Gene, Controls in Vitro Invasiveness and Expression of Matrix Metalloproteinases in Glioma Cells through the ERK1/2 Pathway

Abstract

Gliomas take a number of different genetic routes in the progression to glioblastoma multiforme, a highly invasive variant that is mostly unresponsive to current therapies. Gliomas express elevated levels of matrix metalloproteinases (MMPs), which have been implicated in the control of proliferation and invasion as well as neovascularization. Progressive loss of LGI1 expression has been associated with the development of high grade gliomas. We have shown previously that the forced re-expression of LGI1 in different glioma cells inhibits proliferation, invasiveness, and anchorage-independent growth in cells null for its expression. Here, using Affymetrix gene chip analysis, we show that reexpression of LGI1 in T98G cells results in the downregulation of several MMP genes, in particular MMP1 and MMP3. LGI1 expression also results in the inhibition of ERK1/2 phosphorylation but not p38 phosphorylation. Inhibition of the MAPK pathway using the pharmacological inhibitors PD98059, U0126, and SB203580 in T98GLGI1-null cells inhibits MMP1 and MMP3 production in an ERK1/2-dependent manner. Treatment of LGI1-expressing cells with phorbol myristate acetate prevents the inhibition of MMP1/3 and restores invasiveness and ERK1/2 phosphorylation, suggesting that LGI1 acts through the ERK/MAPK pathway. Furthermore, LGI1 expression promotes phosphorylation of AKT, which leads to phosphorylation of Raf1Ser-259 , an event shown previously to negatively regulate ERK1/2 signaling. These data suggest that LGI1 plays a major role in suppressing the production of MMP1/3 through the phosphatidylinositol 3-kinase/ERK pathway. Loss of LGI1 expression, therefore, may be an important event in the progression of gliomas that leads to a more invasive phenotype in these cells.Glioblastoma multiforme is the most common malignant tumor of the adult central nervous system and has a median survival time of less than 12 months (1-2). The highly lethal nature of this tumor results from the acquisition of an invasive phenotype that allows the tumor cells to infiltrate surrounding brain tissue. Despite considerable heterogeneity in the genetic abnormalities detected in the various etiologies and histopathologies of these tumors (3), 90% of glioblastoma multiformes share losses of regions on chromosome 10 (4 -8). Using a positional cloning strategy, Chernova et al. (9) identified the LGI1 gene associated with an apparently reciprocal t(10, 19)(q24;q13) chromosome translocation in the T98G glioma cell line.LGI1 is expressed in low grade tumors but not in most of the high grade gliomas or permanent cell lines tested (9 -10). The coincident loss of LGI1 expression with loss of chromosome 10 suggested that it might be important in the malignant progression of gliomas.LGI1 carries a leucine-rich repeat (LRR) 1 motif (9) that places it in the F20 family of LRR genes. Members of this family are predominantly involved in either receptor functions or attachment to the extracellular matrix (11). The strongest homology of the LGI1 LRR is with the slit genes (9),...

Downregulation of major histocompatibility complex antigens in invading glioma cells: stealth invasion of the brain

“…3 Gene expression profiling demonstrated that many genes previously associated with migration and invasion of human glioma cells showed altered levels of expression. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Surprisingly, however, our analysis also revealed downregulation of several MHC class I and II genes in migrating LN229 glioma cells in vitro that was confirmed by RT-PCR analysis. In addition, consistent with these findings, immunohistochemistry of invading GBM tumor cells in vivo demonstrated decreased MHC class I protein expression, in invading glioma cells compared to the high levels of expression observed within the tumor core in both human and murine gliomas.…”

“…[13][14][15][16] Genes that were downregulated fulfilling our criteria included tissue inhibitor of metalloproteinase 3 (TIMP3), GTPase regulator, and transgelin 2. [17][18][19] GTPase regulator is linked to focal adhesion kinase (FAK). FAK has been implicated in glioma cell migration in vitro and glioma cell invasion in vivo.…”

LGI1mutations in autosomal dominant and sporadic lateral temporal epilepsy

“…The structural features of its protein product, which do not resemble those of known ion channel subunits, suggest that LGI1 may not be directly implicated in neuronal transmission [Kunapuli et al, 2004;Staub et al, 2002]. This view has been questioned by recent findings that show association of the Lgi1 protein with the rapidly inactivating Kv1 (shaker type) potassium channel [Schulte et al, 2006].…”

“…Recent studies have implicated LGI1 in the control of proliferation and invasiveness of glioma cell lines [Kunapuli et al, 2003]. Particularly, control of glioma cell invasiveness is achieved by regulating expression of the matrix metalloproteinases MMP1 and MMP3 through the ERK 1/2 pathway, suggesting that LGI1 may serve as a tumor metastasis suppressor gene [Kunapuli et al, 2004].…”

Podocalyxin Increases the Aggressive Phenotype of Breast and Prostate Cancer Cells In vitro through Its Interaction with Ezrin

“…Increased cellular invasion is often accompanied by increased activity of proteins that degrade the extracellular matrix such as members of the MMP family. In addition, the MAPK and PI3K pathways have been shown to regulate expression of MMP family members (31,37,38). Therefore, we assessed the activity and expression of several members of the MMP family in MCF7/PODXL and PC3/PODXL cells.…”