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Characterization of epidermal growth factor receptor gene expression in malignant and normal human cell lines
Abstract:
To investigate the possibility that the epidermal growth factor (EGF) receptor functions as an oncogene product, we have determined the levels of EGF receptor protein and RNA in a variety of malignant and normal human cells, using a specific polyclonal antibody to the EGF receptor and a cDNA clone (plasmid pE7) that encodes the EGF receptor, respectively. Besides A431 epidermoid carcinoma cells, which are known to make large amounts of EGF receptor, cell lines from two ovarian cancers, two cervical cancers, and one kidney cancer were found to contain substantial amounts of receptor protein (11-22% of A431). Normal human fibroblasts (Detroit 551), a human lymphocyte line (IM-9), and a leukemic lymphocyte line (CEM) contained low or undetectable levels of EGF receptor. RNA blot analysis showed that among the human cell lines examined the levels of a 10- and a 5.6-kilobase species of pE7-specific RNA generally correlated with the amount of the EGF receptor protein. Genomic DNA blot analysis revealed that except for A431 none of these cell lines expressing high levels of EGF receptor protein possessed amplified receptor gene sequences. A431 cells are known to secrete a truncated form of the EGF receptor. An abundant 2.9-kilobase RNA is found only in A431 cells; it could encode the truncated form of the EGF receptor.
Insights
Epidermal Growth Factor (EGF) receptor is elevated in various human cancers, suggesting its role as an oncogene. Gene amplification was not the cause in most tested cell lines.
Area of Science:
- Molecular Biology
- Oncology
- Cell Biology
Background:
- The epidermal growth factor (EGF) receptor is implicated in cell growth and cancer.
- Understanding EGF receptor levels in various cancers is crucial for oncogene research.
Purpose of the Study:
- To investigate the role of the EGF receptor as a potential oncogene product.
- To quantify EGF receptor protein and RNA levels in malignant and normal human cells.
Main Methods:
- Utilized a specific polyclonal antibody for EGF receptor protein detection.
- Employed a cDNA clone (plasmid pE7) for EGF receptor RNA analysis.
- Performed RNA blot and genomic DNA blot analyses.
Main Results:
- Substantial EGF receptor protein levels were found in ovarian, cervical, and kidney cancer cell lines.
- EGF receptor levels were low or undetectable in normal fibroblasts and lymphocyte lines.
- RNA levels correlated with protein levels, but gene amplification was not observed in most high-expressing cell lines.
- A unique 2.9-kilobase RNA in A431 cells may encode a truncated EGF receptor.
Conclusions:
- The EGF receptor is overexpressed in several human cancers, supporting its potential oncogenic function.
- Overexpression is not primarily due to gene amplification in these cell lines.
- A specific RNA transcript in A431 cells might be responsible for a truncated EGF receptor form.