Galectin-3 expression: a useful tool in the differential diagnosis of posterior fossa tumors in children.
OBJECTIVE
Galectin-3 (Gal-3) is a glycan-binding protein highly expressed in several tumors, including brain neoplasms. This protein has been demonstrated to be correlated with adverse prognosis in some tumor types. However, the role of Gal-3 in pediatric posterior fossa tumors (PPFTs) has not yet been fully addressed. The goals of this study were to evaluate Gal-3 expression in a series of PPFTs and verify whether this expression is related to patient outcome.


METHODS
Gal-3 expression was analyzed by immunohistochemistry in 42 cases of surgically resected primary PPFTs. Surgeries were performed in our institution from January 2003 to December 2006. Tumor samples consisted of 21 pilocytic astrocytomas (PAs), 13 medulloblastomas, 4 ependymomas, 2 diffuse cerebellar astrocytomas, and 2 atypical teratoid/rhabdoid tumors (AT/RTs).


RESULTS
All PAs and ependymomas strongly showed Gal-3 expression, whereas no immunostaining was observed in medulloblastomas and diffuse astrocytomas. In AT/RTs, Gal-3 expression was conspicuous but heterogeneous, being mainly observed in rhabdoid cells. Concerning the Gal-3 expressing tumors, no relationship was observed between the degree of expression and patient survival. Gal-3 was strongly expressed in reactive astrocytes, normal endothelial cells, and macrophages in the adjacent non-neoplastic brain parenchyma. Interestingly, the endothelial cells in the tumor bulk of PAs lacked Gal-3 expression.


CONCLUSIONS
Gal-3 is differentially expressed in PPFTs, but its expression shows no correlation with patient outcome. However, the evaluation of Gal-3 is helpful in establishing a differential diagnosis among PPFTs, especially between PAs and diffuse astrocytomas, and in some circumstances between medulloblastomas and AT/RTs.
Borges
Carolina Bisinoto
CB
Department of Cell and Molecular Biology and Pathogenic Bioagents, Ribeirão Preto School of Medicine, University of São Paulo, Ribeirão Preto, Brazil.
Bernardes
Emerson Soares
ES
Latorraca
Elder Francisco
EF
Becker
Aline Paixão
AP
Neder
Luciano
L
Chammas
Roger
R
Roque-Barreira
Maria Cristina
MC
Machado
Hélio Rubens
HR
de Oliveira
Ricardo Santos
RS
D014408:Biomarkers, Tumor / Q000032:analysis*; D003937:Diagnosis, Differential; D037502:Galectin 3 / Q000096:biosynthesis*; D006801:Humans; D007150:Immunohistochemistry; D015192:Infratentorial Neoplasms / Q000378:metabolism* / Q000473:pathology; D016133:Polymerase Chain Reaction
D014408:Biomarkers, Tumor; D037502:Galectin 3