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Olig2
expression, GFAP, p53 and 1p loss analysis contribute to glioma
subclassification
Mokhtari
K, Paris S, Aguirre-Cruz L, Privat N, Criniere E, Marie Y, Hauw JJ,
Kujas M, Rowitch D, Hoang-Xuan K, Delattre JY, Sanson M
Laboratoire
de neuropathologie R Escourolle (Pr Hauw), Universite Pierre et Marie
Curie, Paris, France.
The
expression of Olig2, a basic helix-loop-helix (bHLH) transcription
factor involved in oligodendroglial specification, was investigated by
immunohistochemistry in a series of 146 tumours and control
samples.
Olig2
expression was restricted to glial tumours and nontumoral
oligodendrocytes.
It
was higher in oligodendrogliomas as compared to astrocytomas and
oligoastrocytomas, and in grade III as compared to grade II
tumours.
Olig
2 was absent or weakly expressed in glioblastoma (GBM), whereas strong
expression was found in the oligodendroglial foci of GBM with
oligodendroglial component (GBMO).
Double
labelling was performed on a subset of the most typical tumours,
according to the WHO classification.
It
showed a mutual exclusion, at cell level, of Olig2 and GFAP
expression.
In
pure oligodendrogliomas, tumour cells were Olig2+/GFAP-.
In
contrast, two main tumour populations, Olig2+/GFAP- and Olig2-/GFAP+,
were found in both oligoastrocytomas and astrocytomas.
Based
on these data from selected samples, two separate entities can be
established, corresponding to 'pure oligodendrogliomas' and
'astrocytomas and oligoastrocytomas'.
The
relevance of this subdivision is further supported by the association
with 1p loss and a trend to better survival for pure
oligodendrogliomas and with p53 expression and a trend to shorter
survival for astrocytomas and oligoastrocytomas.
Combined
testing of Olig2, 1p status, GFAP and p53 expression may therefore be
helpful in refining current classification and providing more
homogeneous sets of gliomas for clinical studies.
PMID: 15634232 [PubMed - indexed for MEDLINE]
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