OLIG2
Oligodendrocyte transcription factor 2 (Oligo2) (Class B basic helix-loop-helix protein 1) (bHLHb1) (Class E basic helix-loop-helix protein 19) (bHLHe19) (Protein kinase C-binding protein 2) (Protein kinase C-binding protein RACK17) [BHLHB1] [BHLHE19] [PRKCBP2] [RACK17]
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Recent in situ hybridization studies showed that mRNA levels of OLIG1 and OLIG2 transcription factors are elevated in oligodendrogliomas. We raised polyclonal antibodies against a synthetic peptide homologous to the human transcription factor Olig1 and studied by immunohistochemistry the expression of Olig1 in 84 brain tumors and in non-neoplastic brain tissues. All oligodendrogliomas, oligoastrocytomas, and dysembryoplastic neuroepithelial tumors showed moderate to strong intranuclear immunoreactivity in cells morphologically identified as oligodendrocytes. In addition, some astrocytomas showed a slight to moderate intranuclear immunoreactivity. None of the other neuroepithelial and non-neuroepithelial tumors showed nuclear immunoreactivity. Double immunostaining of oligodendrogliomas, oligoastrocytomas, and glioblastoma multiforme (GBM) using antibodies against Olig1 and GFAP showed the presence of 3 different cell populations: 1) immunopositive for Olig1 and immunonegative for GFAP, histologically identified as oligodendrocytes; 2) immunopositive only for GFAP, histologically identified as astrocytes; and 3) immunonegative for both antibodies ("null cells"), histologically observed as a population of cells usually with round nuclei and a small amount of cytoplasm. The use of double immunostaining facilitated the distinction among these 3 different tumors. In summary, the use of immunohistochemistry using Olig1 antibodies alone or in combination with anti-GFAP antibody, which can be performed in the routine diagnostic setting, may help in the diagnosis of neuroepithelial tumors.
MeSH Terms
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Aging
- Astrocytoma
- Basic Helix-Loop-Helix Transcription Factors
- Blotting, Western
- Brain Neoplasms
- Cell Count
- Child
- Child, Preschool
- DNA-Binding Proteins
- Ependymoma
- Glial Fibrillary Acidic Protein
- Humans
- Immunohistochemistry
- Middle Aged
- Nerve Tissue Proteins
- Oligodendroglioma
Because a specific group of oligodendrogliomas is susceptible to adjuvant therapy, it is important to elucidate the biological characteristics of these tumors. In situ hybridization analyses have revealed that Olig genes are expressed in oligodendroglial lineage cells and are highly expressed in oligodendrogliomas. To clarify whether OLIG is a tumor-specific marker for oligodendrogliomas, we have investigated the expression of Olig transcripts by semiquantitative RT-PCR assay and OLIG2 protein with a new antibody in a variety of glial tumors. The semiquantitative RT-PCR revealed that high levels of expression of Olig1 and Olig2 mRNAs were present in anaplastic oligodendrogliomas and anaplastic astrocytomas, while expression of these mRNAs in grade IV glioblastomas was lower than in grade II and grade III gliomas (p < 0.01). Immunohistochemical analyses demonstrated that the mean immunopositive proportion of OLIG2 was 82% in anaplastic oligodendrogliomas but only 34% in anaplastic astrocytomas. Therefore, although OLIG2 expression was detected in a range of gliomas not specific for oligodendrogliomas, the expression level in anaplastic oligodendrogliomas was more uniform and intense than that in other glial tumors. In conclusion, combining Olig mRNA expression and immunohistochemistry of OLIG2 enables oligodendrogliomas to be distinguished from glioblastomas and other astrocytic glial tumors.
MeSH Terms
- Adolescent
- Adrenal Gland Neoplasms
- Adult
- Aged
- Aging
- Basic Helix-Loop-Helix Transcription Factors
- Brain
- Cell Count
- Child
- Child, Preschool
- DNA-Binding Proteins
- Ganglion Cysts
- Glioblastoma
- Humans
- Immunoblotting
- Immunohistochemistry
- Infant
- Middle Aged
- Nerve Tissue Proteins
- Oligodendrocyte Transcription Factor 2
- RNA, Messenger
- Reverse Transcriptase Polymerase Chain Reaction
- Tumor Cells, Cultured