Shared oligodendrocyte lineage gene expression in gliomas and oligodendrocyte progenitor cells.
OBJECTIVE
Gliomas (astrocytic and oligodendroglial) are the most frequently occurring primary neoplasms in the central nervous system (CNS). Histological classification, which can be performed to distinguish astrocytomas from oligodendrogliomas, is essentially based on pathological features and has great prognostic and therapeutic value but lacks reproducibility. Specific markers of cell lineage, especially those f or oligodendrogliomas, are still lacking. The oligodendrocyte lineage (OLIG) genes, transcriptional factors of the basic helix-loop-helix family, have been recently identified in oligodendrocyte progenitor cells (OPCs) in the CNS of developing and adult rodents. Data from a few studies have shown in a small series of brain tumors that OLIG genes characterize oligodendrogliomas. To search for a differential expression of the OLIG genes in subgroups of brain tumors, the authors investigated OLIG1 and OLIG2 gene expression.


METHODS
Using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR), the authors analyzed a series of 89 tumors (71 astrocytic and oligodendroglial tumors, eight ependymomas, three medulloblastomas, four meningiomas, and three schwannomas) and normal human brain tissue samples. It was demonstrated that OLIG gene expression was largely limited to glial tumors, that is, astrocytomas and oligodendrogliomas. A very low level was detected in ependymomas, whereas other tumors lacked OLIG gene expression altogether. Surprisingly, OLIG1 and OLIG2 expressionwas not limited to oligodendroglial tumors, but was observed in astrocytic lesions as well, independent of tumor grade. Interestingly, these genes were expressed at the highest level in pilocytic astrocytomas according to semiquantitative RT-PCR results, which were confirmed on dot blot analysis. In situ hybridization showed that the OLIG2 gene was expressed by tumor cells in pilocytic astrocytomas as well as those in oligodendrogliomas.


CONCLUSIONS
The OLIG genes are additional markers shared by all gliomas andOPCs. These markers may help to classify gliomas, to improve understanding of their histogenesis, and to identify new therapeutic targets.
Bouvier
Corinne
C
Laboratoire des Interactions Neurone-Glie, Groupe Hospitalier Pitié-Salpétrière, Paris, France.
Bartoli
Catherine
C
Aguirre-Cruz
Lucinda
L
Virard
Isabelle
I
Colin
Carole
C
Fernandez
Carla
C
Gouvernet
Joany
J
Figarella-Branger
Dominique
D
D001254:Astrocytoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051792:Basic Helix-Loop-Helix Proteins; D016543:Central Nervous System Neoplasms / Q000235:genetics* / Q000378:metabolism*; D046508:Culture Techniques; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins; D003937:Diagnosis, Differential; D015870:Gene Expression / Q000235:genetics*; D006801:Humans; D017403:In Situ Hybridization / Q000379:methods; D009419:Nerve Tissue Proteins / Q000235:genetics*; D000076104:Oligodendrocyte Transcription Factor 2; D009836:Oligodendroglia / Q000378:metabolism*; D009837:Oligodendroglioma / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020796:Receptor, Platelet-Derived Growth Factor alpha / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000378:metabolism*
D051792:Basic Helix-Loop-Helix Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D009419:Nerve Tissue Proteins; D000076104:Oligodendrocyte Transcription Factor 2; D012333:RNA, Messenger; D020796:Receptor, Platelet-Derived Growth Factor alpha; C405707:OLIG1 protein, human; C405708:OLIG2 protein, human