title: Expression of EAAT-1 distinguishes choroid plexus tumors from normal and reactive choroid plexus epithelium.
abstract: Microscopic distinction of normal choroid plexus (CP) from choroid plexus tumors (CPT) may be difficult, especially in small samples of well-differentiated CP papillomas. So far, there are no established markers that reliably distinguish normal and neoplastic CP epithelium. Recently, a correlation between expression/function of glial glutamate transporters EAAT-1 (GLAST) and EAAT-2 (Glt-1) and tumor proliferation has been reported. Furthermore, we previously found that CPTs frequently express EAAT-1, but not EAAT-2. We now compared expression of EAAT-1, EAAT-2 and GFAP in non-neoplastic CP (n = 68) and CPT (n = 79) by immunohistochemistry. Tissue of normal CP was obtained from 50 autopsy cases (20 normal and 30 pathologic brains) and 18 neurosurgical specimens that included 17 fetal, 21 pediatric and 30 adult cases. In non-neoplastic postnatal CP (n = 51), focal expression of EAAT-1 was found in only two pediatric cases (4%). In CPT, expression of EAAT-1 was found in 64 of 79 (81%) tumor samples and was significantly age-dependent (P < 0.0001). Hence, EAAT-1 expression distinguishes neoplastic from normal CP, both in children (P = 0.0032) and in adults (P < 0.0001). Immunostaining for EAAT-2 in selected samples from cases of different ages showed that normal CP (n = 15) or CPT (n = 16) lacked EAAT-2 expression. GFAP expression was found in 3 of 32 (10%) normal CP and in 28 of 73 (38%) tumor samples. In conclusion, in contrast to neoplastic CP samples, expression of EAAT-1 is exceptionally rare in non-neoplastic CP. Thus, EAAT-1 is superior to GFAP as a helpful diagnostic tool in CP samples.
authors.affiliation: Institute for Brain Research, Eberhard-Karls-University, Tübingen, Germany. rudi.beschorner@med.uni-tuebingen.de
authors.forename: Rudi
authors.initials: R
authors.lastname: Beschorner
authors.forename: Georgios
authors.initials: G
authors.lastname: Pantazis
authors.forename: Astrid
authors.initials: A
authors.lastname: Jeibmann
authors.forename: Jana
authors.initials: J
authors.lastname: Boy
authors.forename: Richard
authors.initials: R
authors.lastname: Meyermann
authors.forename: Michel
authors.initials: M
authors.lastname: Mittelbronn
authors.forename: Jens
authors.initials: J
authors.lastname: Schittenhelm
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002831:Choroid Plexus / Q000196:embryology / Q000378:metabolism* / Q000502:physiology*; D016545:Choroid Plexus Neoplasms / Q000196:embryology / Q000378:metabolism*; D004848:Epithelium / Q000196:embryology / Q000378:metabolism; D027341:Excitatory Amino Acid Transporter 1 / Q000378:metabolism*; D027342:Excitatory Amino Acid Transporter 2; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D050491:Glutamate Plasma Membrane Transport Proteins / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D027341:Excitatory Amino Acid Transporter 1; D027342:Excitatory Amino Acid Transporter 2; D005904:Glial Fibrillary Acidic Protein; D050491:Glutamate Plasma Membrane Transport Proteins; C493397:SLC1A2 protein, human; C493394:SLC1A3 protein, human