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Expression of type II iodothyronine deiodinase in brain tumors
M Murakami1, O Araki, T Morimura
1First Department of Internal Medicine, Gunma University School of Medicine, Maebashi, Japan. mmurakam@showa.gunma-u.ac.jp
Abstract:
Type II iodothyronine deiodinase (DII) messenger ribonucleic acid (mRNA) and its activity have been demonstrated in human normal brain. Although DII activity has been demonstrated in brain tumors, expression of DII mRNA has not been studied in these tumors. To investigate the mechanisms involved in the expression of DII activity in brain tumors, we studied DII mRNA and DII activity in astrocytoma (two cases), glioblastoma (three cases), and oligodendroglioma (one case). DII mRNA, the size of which was indistinguishable from that in control cerebral cortical tissue, was demonstrated in all of the brain tumors tested, although the intensity of the hybridization signal showed wide variation among the tumors. DII activity was also detected in all tumors. DII mRNA and DII activity were highest in the tissue from oligodendroglioma. A significantly positive correlation was observed between DII mRNA and DII activity in these tumors (r = 0.94; P < 0.01), suggesting that DII expression in brain tumors is regulated at the pretranslational level. The present results demonstrate, for the first time, that DII mRNA as well as DII activity are expressed in brain tumors, and that DII mRNA is significantly correlated with DII activity in those tissues.
Insights
Type II iodothyronine deiodinase (DII) messenger ribonucleic acid (mRNA) and activity are present in brain tumors. Their expression is linked, suggesting pretranslational regulation in these tissues.
Area of Science:
- Neuroendocrinology
- Molecular Biology
- Oncology
Background:
- Type II iodothyronine deiodinase (DII) is crucial for thyroid hormone metabolism in the brain.
- While DII activity is known in brain tumors, DII mRNA expression remains uncharacterized.
Purpose of the Study:
- To investigate the expression of DII mRNA and activity in human brain tumors.
- To explore the relationship between DII mRNA levels and DII activity in these tumors.
Main Methods:
- Analysis of DII mRNA expression using hybridization techniques.
- Measurement of DII enzymatic activity in tumor tissue samples.
- Study included astrocytoma, glioblastoma, and oligodendroglioma samples.
Main Results:
- DII mRNA was detected in all tested brain tumors, with varying signal intensity.
- DII activity was also present in all tumor samples.
- Oligodendroglioma showed the highest levels of both DII mRNA and activity.
- A strong positive correlation (r = 0.94, P < 0.01) was found between DII mRNA and DII activity.
Conclusions:
- This is the first demonstration of both DII mRNA and activity expression in human brain tumors.
- DII expression in brain tumors appears to be regulated at the pretranslational level.
- Findings suggest a potential role for DII in brain tumor biology.