Springer 2005
Journal of Neuro-Oncology (2006) 77: 25–32 DOI 10.1007/s11060-005-9010-3
Laboratory Investigation - human/animal tissue
Expression of syndecans, a heparan sulfate proteoglycan, in malignant gliomas: participation of nuclear factor-jB in upregulation of syndecan-1 expression Arata Watanabe1, Tadashi Mabuchi2, Eiji Satoh1, Koro Furuya1, Lei Zhang1, Shuichiro Maeda2 and Hirofumi Naganuma1 1 Department of Neurosurgery, University of Yamanashi, Faculty of Medicine, 409-3898, Nakakoma-gun, Yamanashi, Japan; 2Department of Biochemistry, University of Yamanashi, Faculty of Medicine, 409-3898, Nakakoma-gun, Yamanashi, Japan
Key words: malignant glioma, nuclear factor-kappaB, syndecan, syndecan-1 Summary Invasion of tumor cells into the surrounding normal brain tissues is a prominent feature of malignant gliomas. Malignant glioma cells secrete thrombospondin-1 which participates in the motility of glioma cells and binds cell surface heparan sulfate proteoglycan. To clarify the invasion mechanism of tumor cells, expression of the syndecans (syndecan-1, -2, -3, and -4), a major cell surface heparan sulfate proteoglycan family, was analyzed in malignant gliomas. Involvement of nuclear factor-kappaB (NF-jB) on syndecan-1 expression was also investigated. Using reverse transcription-PCR, the authors analyzed the expression of syndecan-1, -2, -3, and -4 in 10 malignant glioma cell lines, 2 glioblastoma specimens, and 2 normal brain specimens. All malignant glioma cell lines and glioblastoma specimens expressed all types of syndecan mRNA, except in one glioma cell line that lacked syndecan-3 expression. On the other hand, normal brain specimens expressed syndecan-2, -3, and -4 mRNA, but did not syndecan-1 mRNA. Syndecan-1 protein was localized in the cell surface of all malignant glioma cell lines by flow cytometry. Various levels of active nuclear factor-kappa B (NF-jB) was detected in all malignant glioma cell lines using immunoblotting. The expression of active NF-jB and syndecan-1 increased in U251 glioma cells after tumor necrosis factor-a or interleukin-1b treatment, which can activate NF-jB. The amplification of active NF-jB and syndecan-1 by tumor necrosis factor-a or interleukin-1b was suppressed by an inhibitor of NF-jB activation (emodin). Emodin also downregulated the expression of syndecan-1 mRNA in U251 cells. These results indicate that malignant glioma cells express all types of syndecans and suggest that NF-jB participates in the upregulation of the syndecan-1 expression at the transcriptional level, and increased expression of syndecan-1 could associate with extracellular matrices including thrombospondin-1.
Introduction Malignant glioma is characterized by invasion of the surrounding normal brain tissues, preferentially along the white matter fiber tracts [1]. The interactions between cell surface molecules and extracellular matrices secreted by glioma cells are not fully understand. We have shown in previous studies the malignant glioma cells secreted thrombospondin-1 (TSP-1) [2] and significant amounts of both TSP-1 and TGF-b proteins were present in malignant glioma tissues, but not in normal brain tissues [3]. We also showed that TSP-1 participates in the motility of glioma cells [4]. TSP-1 is involved in cell–cell and cell–extracellular matrix adhesion [5]. Expression of heparan sulfate proteoglycans (HSPGs) is greater in gliomas compared with normal brain tissues [6]. Expression of HSPGs in astrocytic-derived primary brain tumors may be correlated with the progression of these tumors. TSP-1 binds to cell surface HSPGs as well as integrins [5]. The syndecans are a major family of cell surface HSPGs and may function as receptors of TSP-1 [7,8]. The syndecans are a family of transmembrane
HSPGs, consisting of syndecan-1, -2 (fibroglycan), -3 (N-syndecan), and -4 (ryudocan, amphiglycan) [8,9]. Syndecans bind a variety of extracellular ligands via covalently bonded heparan sulfate chains, and are thought to be important in cell–matrix and cell–cell adhesion, migration, and growth factor signaling. Analysis of syndecan expression in a number of tissues and cell lines indicated that virtually all cells express at least one type of syndecan, most cells express multiple types, and a distinct pattern of syndecan expression characterizes individual cell types and tissues [10]. These reports suggest that syndecans are potential receptor for TSP-1 and may participate in the motility of glioma cells. We found that syndecan-1 molecule was expressed in a cell surface of malignant glioma cells [2]. However, the expression pattern of the syndecans has not been investigated in malignant gliomas. Malignant glioma cells show increased activity of nuclear factor-kappaB (NF-jB) [11]. A possible binding site for NF-jB was identified in the upstream region of syndecan-1 gene by database analysis. This suggests that syndecan-1 expression may be regulated by NF-jB.
26 Syndecan-1 expression is affected by exposure to fibroblast growth factor-2 (FGF-2) or TGF-b in some cells [12,13]. The mechanism of regulation of the syndecan-1 expression remains unclear in malignant glioma cells. The present study investigated the expression of the syndecan family (syndecan-1, -2, -3, and -4) in malignant glioma cell lines, malignant glioma tissues, and normal brain tissues. Specific expression of syndecan-1 was found in malignant glioma cells as well as other types of syndecans. Then we investigated the association between syndecan-1 expression and NF-jB activity. We also examined the effect of anti-TGF-b1/b2/b3 and antiFGF-2 neutralizing antibodies on syndecan-1 expression.
Materials and methods Cell lines and surgical specimens Ten human malignant glioma cell lines (KG1C, T98G, U251, A172, TM2, YMG1, YMG2, YMG3, YMG4, and YMG5) and one human lung adenocarcinoma cell line (A549) were maintained in RPMI-1640 medium supplemented with 10% fetal bovine serum, 2 mM glutamine, and 100 lg/ml kanamycin. The T98G, U251, A172, KG1C, and A549 cell lines were obtained from the Health Science Research Resources Bank, Tokyo, Japan. The TM2 cell line was donated by Dr. Kurimoto, Department of Neurosurgery, Toyama Medical and Pharmaceutical University, Toyama, Japan. The YMG1, YMG2, YMG3, YMG4, and YMG5 cell lines were derived from glioblastoma or anaplastic astrocytoma and established in our laboratory [14]. Glioblastoma specimens were resected from two patients at surgery. The normal brain specimens were obtained from the corticotomy through which the deep-seated tumors were removed, and were not involved in the tumor based on findings of magnetic resonance imaging scans. We obtained the informed consent of the patients for the research use of surgical specimens. RNA isolation Ten human malignant glioma cell lines were cultured in 9-cm dishes. Subconfluent tumor cells were collected after incubation with 0.25% trypsin and 0.02% EDTA, and then washed once with phosphate–buffered saline (PBS). Total RNA was isolated by the single-step method using ISOGEN (Nippon Gene Inc., Toyama, Japan) according to the manufacturer’s instructions. Total RNA was also isolated from the two glioblastoma specimens and the two normal brain specimens obtained at surgery. Reverse transcription-PCR analysis Reverse transcription-PCR (RT-PCR) was performed using 0.5 lg total RNA, 0.2 lM primers, and a kit for RT-PCR (Takara Shuzo Co., Ltd., Shiga, Japan). Primer sets for syndecans were designed from sequences in the GenBank database. GenBank accession numbers are: syndecan-1, XM_002690; syndecan-2, J04621;
syndecan-3, NM_014654; and syndecan-4, XM_009530. Primer sequences were as follows: syndecan-1, 5¢-CCC TGA AGA TCA AGA TGG CTC T-3¢ (sense) and 5¢CCC GAG GTT TCA AAG GTG AAG T-3¢ (antisense); syndecan-2, 5¢-CGA CCA CTT CCA AAG ATA CT-3¢ (sense) and 5¢-CGC ATA AAA CTC CTT AGT AG-3¢ (antisense); syndecan-3, 5¢-CTT CTG CCT CTC CCA CTG AC-3¢ (sense) and 5¢-CAC CCC GCC CAC AAT CAC AG-3¢ (antisense); syndecan-4, 5¢-CTC CTA GAA GGC CGA TAC TTC T-3¢ (sense) and 5¢-GGA CCT CCG TTC TCT CAA AGA T-3¢ (antisense); and glyceraldehyde-3–phosphate dehydrogenase (GAPDH) [3], 5¢-TGG TAT CGT GGA AGG ACT CAT GAC-3¢ (sense) and 5¢-ATG CCA GTC AGC TTC CCG TTC AGC-3¢ (antisense). PCR amplification was performed for 30 cycles in a DNA thermocycler (Takara Shuzo Co., Ltd.) using denaturation for 30 s at 94 C, annealing for 30 s at 55 C for syndecan-2 and -4 and at 58 C for syndecan-1 and -3 and GAPDH, and extension for 1 min at 72 C. Amplified PCR products were analyzed on 1.5% agarose gels. For direct sequencing, the PCR products were purified from agarose gels using the QIAquick gel extraction kit (Qiagen K.K., Tokyo, Japan) according to the manufacturer’s instructions. Flow cytometry analysis of syndecan-1 expression Since transcription levels are not always consistent with protein levels in the cells, the expression of syndecan-1 protein on the cell surface was examined by flow cytometry in 10 malignant glioma cell lines. The A549 lung adenocarcinoma cell line was also examined, as a positive control of syndecan-1 expression [15]. Tumor cells cultured in 6-well plates were washed once with PBS and incubated in PBS with 0.2% EDTA and 5% fetal calf serum for 30 min at 4 C. The tumor cells were collected by gentle pipetting and washed twice with PBS. Tumor cells were also collected by incubating with 0.25% trypsin and 0.02% EDTA, since trypsin releases syndecan-1 at the portion adjacent to the membrane-attachment site in the ectodomain [16,17]. Tumor cells were incubated with phycoerythrin-conjugated anti-syndecan-1 antibody (CD138; DAKO, Glostrup, Denmark) for 30 min at 4 C. As a negative control, tumor cells were treated with phycoerythrinconjugated mouse immunoglobulin 1 (Becton Dickinson, San Jose, CA). After washing twice, tumor cells were analyzed by flow cytometry (FACSCaliber, Becton Dickinson). More than 1104 cells were analyzed in each sample. Western blot analysis for active NF-jB Ten human malignant glioma cell lines were cultured in 9 cm dishes. Subconfluent tumor cells were collected after incubation with 0.25% trypsin and 0.02% EDTA. U251 cells were cultured in 6 cm dishes, treated with 500 U/ml of TNF-a (Dainippon Pharmaceutical Co., Osaka, Japan) for 15, 30, 45, and 60 min, and then collected, since TNF-a activates NF-jB [18]. U251 cells cultured in 6-well plates were also treated for 20 min
27 with 500 U/ml of TNF-a or IL-1b (Genzyme/Techne, Minneapolis, MN), with or without 50 lg/ml of emodin (3-methyl-1,6,8-trihydroxyanthraquinone; Sigma– Aldrich Corp., St. Louis, MO), and then collected. IL1b also activates NF-jB [18]. The cell pellets were lysed with RIPA buffer (5 M NaCl, 1% Nonidet P-40, 0.5% sodium deoxycholate, 0.1% sodium dodecyl sulfate, 1 M Tris–HCl, pH 8.0). The lysates (50 lg protein) were separated on a 10% sodium dodecyl sulfate polyacrylamide gel (TEFCO, Tokyo, Japan) and electroblotted on polyvinylidene difluoride membrane (Millipore, Bedford, MA). The membrane was treated with 5% bovine serum albumin. After washing, the membrane was incubated with rabbit anti-phosphoNF-jB p65 antibody (1:1000) (Cell Signaling Technology, Inc., Beverly, MA) for 1 h at room temperature. After washing, the membrane was treated with anti-rabbit antibody conjugated with alkaline phosphatase (DAKO) for 30 min at room temperature. After washing, the membrane was equilibrated with detection buffer for 3 min and then incubated with CDP-Star (Roche Diagnostics, Mannheim, Germany) substrate to develop the signal. The immunoblot signals were visualized by chemiluminescence and recorded using a Fuji LAS1000 Lumino Image Analyzer (Fuji Photo Film, Tokyo, Japan). As an internal control for protein content, the lysates were analyzed using anti-actin antibody (Santa Cruz Biotechnology, Santa Cruz, CA). Effect of inhibitor of NF-jB activation, TNF-a, and IL-1b on syndecan-1 expression U251 cells cultured in 6-well plates were treated with 25 or 50 lg/ml of emodin for 16 h and the cell surface expression of syndecan-1 was examined by flow cytometry. Total RNA was extracted from U251 cells treated with 50 lg/ml of emodin for 12 h as described above and subjected to Northern blot analysis. To examine the effects of TNF-a and IL-1b on syndecan-1 expression, U251 cells cultured in 6-well plates were treated for 16 h with 500 U/ml of TNF-a or IL-1b, with or without 50 lg/ ml of emodin. Then, the U251 cells were analyzed for syndecan-1 expression by flow cytometry. Northern blot analysis RNA samples (20 lg) were separated on 1% agarose gel containing 37% formaldehyde and transferred to a Zeta-Probe nylon membrane (Bio-Rad, Hercules, CA). The RNAs were fixed on the membrane using an UV cross-linker (Stratagene, La Jolla, CA). The membrane was prehybridized in DIG-Easy Hyb hybridization buffer (Roche Diagnostics) and then hybridized in the same buffer for 16 h at 42 C to digoxigenin-labeled syndecan-1 and GAPDH probes. After high stringency washing, the membrane was incubated in blocking solution (Roche Diagnostics), followed by blocking solution containing the anti-digoxigenin–alkaline phosphatase conjugate, and then incubated with CDP-Star (Roche Diagnostics). The hybridization signals visualized with chemiluminescence were recorded using a Fuji
LAS1000 Lumino Image Analyzer (Fuji Photo Film). The syndecan-1 mRNA content in the samples was evaluated by densitometry using a National Institutes of Health image analysis system. Effect of anti-TGF-b or anti-FGF-2 neutralizing antibody on syndecan-1 expression U251 cells cultured in 6-well plates were treated with 20 lg/ml of anti-TGF-b1/b2/b3 neutralizing antibody (Genzyme/Techne), anti-FGF-2 neutralizing antibody (Genzyme/Techne), or normal mouse immunoglobulin G for 24 h and the cell surface expression of syndecan-1 was examined by flow cytometry.
Results RT-PCR analysis Expression of syndecans was analyzed by RT-PCR using total RNA extracted from 10 malignant glioma cell lines, two glioblastoma specimens, and two normal brain specimens as templates. As shown in Figure 1A, all malignant glioma cell lines expressed mRNA of all syndecan types, except one cell line (YMG3) that lacked syndecan-3 mRNA expression. The nucleotide sequences of PCR products for all syndecans were completely identical to the reported sequences of each syndecan. Figure 1B shows the results of RT-PCR analysis of the two glioblastoma specimens and two normal brain specimens. The glioblastoma specimens expressed all syndecans as in the malignant glioma cell lines. However, the normal brain specimens expressed only three syndecans, syndecan-2, -3, and -4. Cell surface expression of syndecan-1 in malignant glioma cells All malignant glioma cell lines expressed significant amounts of syndecan-1 on the cell surfaces (Figure 2A). Eight of the ten malignant glioma cell lines showed high levels of syndecan-1 expression, whereas two cell lines (YMG1 and YMG3) showed low levels of expression. Figure 2B shows that the expression of syndecan-1 was abolished in the trypsin-treated cell lines, confirming the syndecan-1 expression on the surface of the glioma cells. Active NF-kB expression in malignant glioma cells We examined the constitutive expression of active NFjB (phospho-NF-jB) in malignant glioma cells, since malignant glioma cells show increased NF-jB activity [11]. Figure 3 shows that all 10 malignant glioma cell lines constitutively expressed various levels of active NF-jB. Next, we examined the pattern of response of active NF-jB expression in U251 cells after TNF-a treatment, since TNF-a activates NF-jB [18]. Figure 4A shows that active NF-jB was maximally amplified at 15 min after the TNF-a treatment and then gradually decreased. Then, we examined the effect of emodin, an inhibitor of NF-jB activation [19], on the amplified
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Figure 1. RT-PCR analysis of mRNA of syndecans in malignant gliomas. (A) All 10 malignant glioma cell lines expressed mRNA of all syndecans, except the YMG3 cell line that lacked syndecan-3 mRNA expression. PCR product sizes are 563, 390, 552, 346, and 189 bp for syndecan-1, -2, -3, -4, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), respectively. (B) Analysis in two glioblastoma specimens and two normal brain specimens. The glioblastoma specimens (tumor 1 and tumor 2) expressed the mRNA of syndecan-1, -2, -3, and -4, whereas the normal brain specimens (normal 1 and normal 2) expressed only the mRNA of syndecan-2, -3, and -4. GAPDH, glyceraldehyde-3-phosphate dehydrogenase.
Figure 2. Flow cytometry analysis of syndecan-1 expression in malignant gliomas. (A) All 10 malignant glioma cell lines expressed significant amounts of syndecan-1 on the cell surfaces. Dotted line, negative control; thin line, syndecan-1-positive cells. (B) Release of the extracellular domain of the syndecan-1 molecule by trypsin treatment. The A549 lung adenocarcinoma (a) and KG1C malignant glioma cells (c) collected using EDTA treatment show syndecan-1 expression on the cell surfaces by flow cytometry. Treatment of A549 (b) and KG1C cells (d) with trypsin abolished the expression of syndecan-1 on the cell surfaces, confirming the presence of the syndecan-1 molecule. Dotted line, negative control; thin line, syndecan-1-positive cells.
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Figure 3. Western blot analysis of active NF-jB (phospho-NF-jB/ p65) in malignant glioma cell lines. Various levels of active NF-jB were detected in all glioma cell lines.
NF-jB expression after TNF-a or IL-1b treatment. U251 cells were treated with TNF-a or IL-1b for 20 min, with or without emodin. Figure 4B shows that the amplified expression of active NF-jB by TNF-a or IL1b was partially inhibited by emodin. Effect of inhibitor of NF-jB activation, TNF-a, and IL-1b on syndecan-1 expression A possible binding site ()366 to )357: 5¢-GGGGCGTTCC-3¢) for NF-jB was identified in the upstream region of syndecan-1 gene by database analysis. Then, we examined the involvement of NF-jB in syndecan-1 expression by using emodin in U251 cells. Flow cytome-
Figure 4. Effect of cytokines and emodin on the expression of active NF-jB in U251 cells. (A) Effect of TNF-a on the expression of active NF-jB in glioma cells. U251 cells were treated with 500 U/ml of TNFa for 15, 30, 45 and 60 min, and analyzed by Western blotting. (B) Effect of inhibitor of NF-jB activation (emodin) on the expression of active NF-jB after treatment with TNF-a or IL-1b. U251 cells were treated with TNF-a (500 U/ml) or IL-1b (500 U/ml) for 20 min, with or without emodin (50 lg/ml) treatment, and analyzed by Western blotting.
try analysis showed that treatment of U251 cells with 25 and 50 lg/ml of emodin decreased the expression of syndecan-1 protein in a dose-dependent manner by 17.6 ± 9.2% (mean ± SD, n = 3) and 42.8 ± 7.9%, respectively (Figure 5A). Next we examined the effect of TNF-a and IL-1b on the syndecan-1 expression, since both cytokines increased NF-jB activity. Both TNF-a and IL-1b upregulated the syndecan-1 expression (Figure 5B, a and b). The upregulated syndecan-1 expression by TNF-a or IL-1b decreased by emodin treatment (Figure 5B, c and d). The effects of emodin on the transcription of syndecan1 gene were also confirmed by Northern blot analysis. The approximate sizes of the syndecan-1 mRNA were determined to be 3.2 and 2.8 kb. This agrees with a previous report which showed two transcripts of syndecan-1 mRNA [13]. Syndecan-1 mRNA expression decreased after the emodin treatment (Figure 6). Densitometric analysis showed that reduction rates of the two transcripts after emodin treatment were 61.7+/)5.8 % and 51.6+/)7.8 % (mean +/) SD; n = 3), respectively. These results suggest that NF-jB is involved in the regulation of the syndecan-1 expression at the transcriptional level. Effect of anti-TGF-b or anti-FGF-2 neutralizing antibodies on syndecan-1 expression Treatment with the anti-TGF-b1/b2/b3 and anti-FGF-2 neutralizing antibodies did not alter syndecan-1 expression in U251 cells (Figure 7).
Discussion The present study investigated the pattern of expression of syndecan family in human malignant gliomas and nonneoplastic brain tissues. Constitutive expression of syndecan-2, -3, and -4 was found in the normal brain tissues as well as in malignant gliomas, and additional expression of syndecan-1 in the malignant glioma cells. The normal brain tissues lacked the syndecan-1 expression. Flow cytometry analysis confirmed the expression of syndecan-1 protein in the malignant glioma cell lines. The present results suggest that the presence of active NF-kB is involved in the syndecan-1 expression in malignant glioma cells. Several reports suggest that syndecan-1 is a key molecule in the motility of cells. The cytoplasmic domain of syndecan-1 is essential for association with the actin cytoskeleton [20]. Raji lymphoid cells which express syndecan-1 bind and spread rapidly when attached to matrix ligands that contain heparan sulfatebinding domains [21]. Syndecan-1 is also crucial in coupling the organization of fascin spikes in response to a physiological extracellular ligand, TSP-1, and overexpression of syndecan-1 in a heterologous cell type is sufficient to cause dramatic enhancement of cell spreading and the formation of fascin spikes in response to TSP-1 [7]. The present study showed that malignant glioma cells expressed significant levels of syndecan-1. Furthermore, our previous studies showed that TSP-1
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Figure 5. Effect of inhibitor of NF-jB activation (emodin) on syndecan-1 expression. (A) U251 cells were treated with 25 and 50 lg/ml of emodin for 16 h and syndecan-1 expression was analyzed by flow cytometry (a). Data is expressed as % change of syndecan-1 expression compared to untreated cells (b). The horizontal bar indicates mean value ± SD (n = 3). Treatment with 25 and 50 lg/ml of emodin decreased the expression by 17.6 ± 9.2% and 42.8 ± 7.9%, respectively. (B) Effect of emodin on syndecan-1 expression after treatment with TNF-a or IL-1b. U251 cells were treated with 500 U/ml of TNF-a (a) or IL-1b (b) for 16 h and syndecan-1 expression was analyzed by flow cytometry. U251 cells were also treated with 500 U/ml of TNF-a (c) or IL-1b (d) together with emodin
expression apparently increased cell motility in malignant glioma cells [4], and malignant glioma cells expressed and secreted significant amounts of TSP-1 proteins [2,3]. These observations suggest that the interaction between syndecans and TSP-1 is important in the spread of malignant glioma cells. The molecular mechanisms that regulate syndecan-1 expression are not well known, especially in humans. In the mouse, the promoter region of syndecan-1 contains
Figure 6. Northern blot analysis of syndecan-1 expression after treatment with emodin. U251 cells were treated with 50 lg/ml of emodin for 12 h. Emodin treatment downregulated the expression of syndecan-1 mRNA. The approximate sizes of syndecan-1 mRNA were determined to be 3.2 and 2.8 kb. The amount of RNA was normalized by GAPDH. The data represents three experiments.
Figure 7. Flow cytometric analysis of syndecan-1 expression after neutralizing antibodies treatments. U251 cells were treated with 20 lg/ ml of anti-TGF-b (A) or anti-FGF-2 (B) neutralizing antibodies for 24 h. The neutralizing antibodies treatments did not alter syndecan-1 expression. Dotted line indicates the antibody treatment. The data represents three experiments.
31 an array of consensus transcription factor binding sites, which include NF-jB, SP1, TATA box, and CAAT box [22]. Data base analysis has shown a possible binding site for NF-jB in the upstream of the human syndecan-1 gene and human malignant glioma cells show increased NF-jB activity [11]. Our study found that NF-jB was constitutively activated in malignant glioma cells, and that an inhibitor of NF-jB activation (emodin) and activators of NF-jB (TNF-a and IL-1b) affected the expressions of both active NF-jB and syndecan-1. These results suggest that NF-jB participates in the upregulation of syndecan-1 expression at the transcriptional level in malignant glioma cells. The presence of active NF-jB plays important roles in the development and progression of a number of human malignancies [23]. Several genes that are involved in cellular transformation, proliferation, invasion, and angiogenesis are regulated by NF-jB [24,25]. This suggests that NF-jB also plays an important role in the progression of malignant gliomas. We also examined the role of TGF-b and FGF-2 on syndecan-1 expression using neutralizing antibodies, since syndecan-1 expression is affected by exposure to FGF-2 or TGF-b in some cells [12,13]. The present data suggest that TGF-b and FGF-2 may not affect syndecan-1 expression in malignant glioma cells, although they produce both cytokines [3,26,27]. In conclusion, malignant glioma cell lines and glioblastoma specimens expressed all types of syndecans. Expression of syndecan-1 was specific to malignant gliomas and was absent in normal brain tissues. An increase of active NF-jB upregulated syndecan-1 expression. These results suggest that NF-jB participates in the upregulation of syndecan-1 expression in malignant gliomas, and that syndecan-1 expression may increase the invasiveness of malignant glioma cells via the interaction between syndecan-1 and extracellular ligands including TSP-1.
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Address for offprints: Hirofumi Naganuma, Department of Neurosurgery, Faculty of Medicine, 1110 Shimokato, Tamaho-cho, 409-3898, Nakakoma-gun, Yamanashi, Japan; Tel.: +81-55-273-6786; Fax: +81-55-274-2468; E-mail:
[email protected].
