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Epidermal growth factor receptor gene-amplified MDA-468 breast cancer cell line and its nonamplified variants
Abstract:
We have recently reported (J. Filmus, M. N. Pollak, R. Cailleau, and R. N. Buick, Biochem. Biophys. Res. Commun. 128:898-905, 1985) that MDA-468, a human breast cancer cell line with a high number of epidermal growth factor (EGF) receptors, has an amplified EGF receptor gene and is growth inhibited in vitro pharmacological doses of EGF. We have derived several MDA-468 clonal variants which are resistant to EGF-induced growth inhibition. These clones had a number of EGF receptors, similar to normal human fibroblasts, and had lost the EGF receptor gene amplification. Karyotype analysis showed that MDA-468 cells had an abnormally banded region (ABR) in chromosome 7p which was not present in the variants. It was shown by in situ hybridization that the amplified EGF receptor sequences were located in that chromosome, 7pABR. Five of the six variants studied were able to generate tumors in nude mice, but their growth rate was significantly lower than that of tumors derived from the parental cell line. The variant that was unable to produce tumors was found to be uniquely dependent on EGF for growth in soft agar.
Insights
Human breast cancer cells with amplified epidermal growth factor (EGF) receptors are inhibited by EGF. Variants lacking gene amplification show resistance, indicating EGF receptor gene amplification drives EGF-driven growth inhibition in MDA-468 cells.
Area of Science:
- Molecular Biology
- Cancer Research
- Genetics
Background:
- MDA-468 cells, a human breast cancer line, exhibit numerous epidermal growth factor (EGF) receptors.
- These cells possess an amplified EGF receptor gene and show growth inhibition when exposed to pharmacological doses of EGF.
- Previous research indicated a link between EGF receptor gene amplification and EGF-induced growth inhibition in MDA-468 cells.
Purpose of the Study:
- To investigate the role of EGF receptor gene amplification in EGF-induced growth inhibition.
- To characterize clonal variants of MDA-468 cells that are resistant to EGF-induced growth inhibition.
- To determine the correlation between EGF receptor gene amplification, receptor number, and tumor formation in vivo.
Main Methods:
- Derivation and characterization of MDA-468 clonal variants resistant to EGF.
- Quantification of EGF receptors in parental and variant cell lines.
- Karyotype analysis and in situ hybridization to locate EGF receptor gene amplification.
- Tumorigenicity assays in nude mice and soft agar growth assays.
Main Results:
- Clonal variants resistant to EGF-induced growth inhibition were successfully derived.
- These variants displayed a normal number of EGF receptors and lacked the amplified EGF receptor gene.
- The amplified EGF receptor gene sequences were localized to an abnormally banded region (ABR) on chromosome 7p in MDA-468 cells.
- Tumor growth rates in nude mice were significantly lower for variants compared to the parental cell line.
- One variant, unable to form tumors, showed a unique dependence on EGF for growth in soft agar.
Conclusions:
- EGF receptor gene amplification in MDA-468 cells is directly responsible for EGF-induced growth inhibition.
- Loss of EGF receptor gene amplification leads to resistance to EGF-induced growth inhibition.
- Tumorigenicity and growth characteristics are influenced by EGF receptor gene status and EGF dependence.