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Expression of epidermal growth factor receptors in human brain tumors
Abstract:
The expression of receptors for epidermal growth factor (EGF-R) was determined in 29 samples of brain tumors from 22 patients. Primary gliogenous tumors, of various degrees of cancer, five meningiomas, and two neuroblastomas were examined. Tissue samples were frozen in liquid nitrogen immediately after the operation and stored at -70 degrees until use. Cerebral tissue samples from 11 patients who died from diseases not related to the central nervous system served as controls. Immunoprecipitation of functional EGF-R-kinase complexes revealed high levels of EGF-R in all of the brain tumors of nonneuronal origin that were examined. The level of EGF-R varied between tumors from different patients and also between specimens prelevated from different areas of the same tumor. In contrast, the levels of EGF-R from control specimens were invariably low. The biochemical properties of EGF-R in brain tumor specimens were found to be indistinguishable from those of the well-characterized EGF-R from the A-431 cell line, derived from human epidermoid carcinomas. Human brain EGF-R displays a molecular weight of 170,000 by polyacrylamide-sodium dodecyl sulfate gel electrophoresis. It is phosphorylated mainly in tyrosine residues and shows a 2-dimensional phosphopeptide map similar to that obtained with the phosphorylated EGF-R from membranes of A-431 cells. Our observations suggest that induction of EGF-R expression may accompany the malignant transformation of human brain cells of nonneuronal origin.
Insights
High levels of epidermal growth factor receptor (EGF-R) were found in nonneuronal brain tumors. EGF-R expression may indicate malignant transformation in these brain tumors.
Area of Science:
- Neuro-oncology
- Molecular biology
- Biochemistry
Background:
- Epidermal Growth Factor Receptor (EGF-R) plays a role in cell growth and is implicated in various cancers.
- Understanding EGF-R expression in brain tumors is crucial for diagnosis and potential therapeutic strategies.
Purpose of the Study:
- To investigate the expression levels and biochemical properties of EGF-R in different types of human brain tumors.
- To compare EGF-R in brain tumors with control brain tissue and a known cancer cell line.
Main Methods:
- Immunoprecipitation of EGF-R-kinase complexes from 29 brain tumor samples and 11 control samples.
- Analysis of EGF-R biochemical properties using SDS-PAGE and 2D phosphopeptide mapping.
- Comparison with EGF-R from the A-431 human epidermoid carcinoma cell line.
Main Results:
- Significantly elevated EGF-R levels were detected in all examined nonneuronal brain tumors (gliomas, meningiomas, neuroblastomas).
- EGF-R levels varied within and between tumors, contrasting with low levels in control brain tissue.
- Biochemical characteristics of brain tumor EGF-R, including molecular weight and phosphorylation patterns, were similar to those of EGF-R from the A-431 cell line.
Conclusions:
- The study suggests that increased EGF-R expression is associated with the malignant transformation of nonneuronal human brain cells.
- EGF-R may serve as a potential biomarker for certain brain tumors.
- The findings warrant further investigation into targeting EGF-R for brain tumor therapies.