Characterization of epidermal growth factor receptor gene expression in malignant and normal human cell lines.

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Abstract
To investigate the possibiity that the epidermal growth factor (EGF) receptor functions as an oncogene product, the levels of EGF receptor protein and RNA were determined in a variety of malignant and normal human cells, using a specific polyclonal antibody to the EGF receptor and a cDNA [complementary DNA] 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 2 ovarian cancers, 2 cervical cancers and 1 kidney cancer contained 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.