Expression of syndecans, a heparan sulfate proteoglycan, in malignant gliomas: participation of nuclear factor-[kappa]B in upregulation of syndecan-1 expression

• Published in: Journal of neuro-oncology 2006-03, Vol.77 (1), p.25
• Main Authors: Watanabe, Arata, Mabuchi, Tadashi, Satoh, Eiji, Furuya, Koro, Zhang, Lei, Maeda, Shuichiro, Naganuma, Hirofumi
• Format: Article
• Language: English
• ISSN: 0167-594X; 1573-7373
• DOI: 10.1007/s11060-005-9010-3

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-κB) 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-κB) was detected in all malignant glioma cell lines using immunoblotting. The expression of active NF-κB and syndecan-1 increased in U251 glioma cells after tumor necrosis factor-α or interleukin-1β treatment, which can activate NF-κB. The amplification of active NF-κB and syndecan-1 by tumor necrosis factor-α or interleukin-1β was suppressed by an inhibitor of NF-κB 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-κB 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.