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Int J Clin Exp Pathol 2013;6(7):1294-1305

Original Article
Expression of the lysosomal-associated membrane protein-1 (LAMP-1) in astrocytomas

Stine S Jensen, Charlotte Aaberg-Jessen, Karina G Christensen, Bjarne Kristensen

Department of Pathology, Odense University Hospital, Institute of Clinical Research, University of Southern Denmark, Denmark

Received May 8, 2013; Accepted May 29, 2013; Epub June 15, 2013; Published July 1, 2013

Abstract: Targeting of lysosomes is a novel therapeutic anti-cancer strategy for killing the otherwise apoptosis-resistant cancer cells. Such
strategies are urgently needed for treatment of brain tumors, especially the glioblastoma, which is the most frequent and most malignant type.
The aim of the present study was to investigate the presence of lysosomes in astrocytic brain tumors focussing also on the therapy resistant
tumor stem cells. Expression of the lysosomal marker LAMP-1 (lysosomal-associated membrane protein-1) was investigated by
immunohistochemistry in 112 formalin fixed paraffin embedded astrocytomas and compared with tumor grade and overall patient survival.
Moreover, double immunofluorescence stainings were performed with LAMP-1 and the astrocytic marker GFAP and the putative stem cell
marker CD133 on ten glioblastomas. Most tumors expressed the LAMP-1 protein in the cytoplasm of the tumor cells, while the blood vessels
were positive in all tumors. The percentage of LAMP-1 positive tumor cells and staining intensities increased with tumor grade but variations in
tumors of the same grade were also found. No association was found between LAMP-1 expression and patient overall survival in the individual
tumor grades. LAMP-1/GFAP showed pronounced co-expression and LAMP-1/CD133 was co-expressed as well suggesting that tumor cells
including the proposed tumor stem cells contain lysosomes. The results suggest that high amounts of lysosomes are present in
glioblastomas and in the proposed tumor stem cells. Targeting of lysosomes may be a promising novel therapeutic strategy against this highly
malignant neoplasm. (IJCEP1305007).

Keywords: LAMP-1, lysosomes, glioblastomas, immunohistochemistry, tumor stem cells

Address correspondence to: Bjarne Winther Kristensen, Department of Pathology, Winsløwparken 15, DK-5000 Odense C. Phone: 0045
65414807; Fax: 0045 66122783; E-mail: bjarne.winther.kristensen@rsyd.dk