Increased expression of highly sulfated keratan sulfate synthesized in malignant astrocytic tumors Yukinari Kato a, * ,1 , Norihito Hayatsu a,b,1 , Mika Kato Kaneko a , Satoshi Ogasawara a , Tetsutaro Hamano c , Satoru Takahashi b , Ryo Nishikawa d , Masao Matsutani d , Kazuhiko Mishima d , Hisashi Narimatsu a,b a Research Center for Medical Glycoscience (RCMG), National Institute of Advanced Industrial Science and Technology (AIST), Open Space Laboratory C-2, 1-1-1, Tsukuba, Ibaraki 305-8568, Japan b Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan c Hamano Statistical Analysis Office 6-7-15, Chuo-cho, Higashikurume-shi, Tokyo 203-0054, Japan d Saitama Medical University International Medical Center 1397-1 Yamane Hidaka-shi, Saitama 350-1298, Japan article info Article history: Received 20 February 2008 Available online 7 March 2008 Keywords: Keratan sulfate Proteoglycan Glycogene Astrocytic tumor Glioblastoma abstract Keratan sulfate (KS) proteoglycans are expressed on a subpopulation of microglia in normal adult brain. We previously showed the up-regulated expression of KS in one of glioblastoma cell lines using anti-KS antibody (5D4). However, it has not been clarified whether KS is expressed in brain tumors and is involved in their malignancy. In this study, 54 astrocytic tumors were investigated about KS-expression using Western-blot with 5D4. In six of 14 anaplastic astrocytomas (43%) and 23 of 34 glioblastomas (68%), KS was detected by 5D4. KS was hardly detected by 5D4 in diffuse astrocytoma, suggesting that KS-expression is significantly expressed in malignant astrocytic tumors. In immunohistochemistry, KS is highly expressed in cell surface of malignant astrocytic tumors. Taken together, KS might be associated with the malignancy of astrocytic tumors, and be useful for a prognostic factor of astrocytic tumors. Ó 2008 Elsevier Inc. All rights reserved. Keratan sulfate (KS) proteoglycans (KSPGs) consist of different core proteoglycans that are individually glycosylated to varying degrees with keratan sulfate chains [1]. Theses keratan sulfates are known to be inhibitory to axonal growth. During development, sulfated keratans are temporally and spatially located in areas in which restricted axonal growth occurs. In the adult, KS is also found on a subpopulation of microglia throughout the brain; how- ever, KS was not detected on astrocyte or oligodendrocyte [2]. KS consists of a linear polymer of N-acetyllactosamine, Galb1-4Glc- NAcb1-3, which is sulfated at the C-6 positions of galactose (Gal) and N-acetylglucosamine (GlcNAc) [1]. Elongation of the carbohy- drate backbone of KS chain is catalyzed by enzymes of two glyco- syltransferase families: b1,3-N-acetylglucosaminyltransferase (b3GnT) and b1,4-galactosyltransferase (b4GalT). Sulfation of the chain is catalyzed by two carbohydrate sulfotransferases. Recent reports have described enzymes which are involved in KS synthesis [3–9]. Keratan sulfate Gal-6-sulfotransferase (KSGal6ST) is for sul- fation of Gal. In addition, N-acetylglucosamine-6-O-sulfotransfer- ase (GlcNAc6ST)-1 and GlcNAc6ST-5 (also known as CGn6ST) are responsible for sulfation of N-acetylglucosamine. Astrocytic tumors are the most common tumors of the central nervous system (CNS) and are categorized into diffuse astrocyto- mas (World Health Organization (WHO) Grade II), anaplastic astro- cytomas (AA; WHO Grade III) and glioblastomas (GBM; WHO Grade IV) [10]. Despite advances in surgical techniques, radiation therapy, and adjuvant chemotherapy, their prognoses remain poor: the median survival time for patients with GBMs is only one year [11]. Glioblastoma may occur de novo or may result from progres- sion of low-grade astrocytomas [12]. Molecular mechanisms of tumorigenesis and malignant progression are associated with the inactivation of tumor suppressor genes such as p53-Rb pathway or the overexpression of oncogenes such as epidermal growth fac- tor receptor (EGFR) [13]. However, the mechanisms of tumorigen- esis and progression of astrocytic tumors have not been resolved completely. Identification of glycogenes or glycans that are ex- pressed differentially in high-grade astrocytomas, low-grade tu- mors or normal brain tissues is important to elucidate the molecular mechanisms of tumorigenesis and to develop novel therapeutic strategies. In our recent study, we investigated the KS expression in glio- blastoma cell lines using a monoclonal anti-KS antibody (5D4) and revealed KS is highly expressed in one of glioblastoma cell lines, LN229 [14]. Furthermore, we investigated the relationship 0006-291X/$ - see front matter Ó 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.bbrc.2008.02.130 Abbreviations: KS, keratan sulfate; KSPGs, KS proteoglycans; Gal, galactose; GlcNAc, N-acetylglucosamine; KSGal6ST, keratan sulfate Gal-6-sulfotransferase; GlcNAc6ST, N-acetylglucosamine-6-O-sulfotransferase; b3GnT, b1,3-N-acetylglucosaminyl- transferase; b4GalT, b1,4-galactosyltransferase. * Corresponding author. Fax: +81 29 861 3191. E-mail address: yukinari-k@bea.hi-ho.ne.jp (Y. Kato). 1 These authors contributed equally to this work. Biochemical and Biophysical Research Communications 369 (2008) 1041–1046 Contents lists available at ScienceDirect Biochemical and Biophysical Research Communications journal homepage: www.elsevier.com/locate/ybbrc