The potential of transforming growth factor alpha (TGF-alpha) to function as an autocrine growth factor was evaluated in 17 ovarian carcinoma cell lines. In 16 of 17 cell lines, radioimmunoassay (RIA) of processed serum- free conditioned medium indicated TGF-alpha concentrations ranging from 16 to 197 pg/ml, or 1.5 to 95 ng/100 million cells. Iodinated-TGF-alpha bound to a single class of high-affinity binding sites on the surface of all 17 cell lines (Kd 0.21 nM to 5.3 nM), with receptor numbers from 3,500 to 96,000 per cell depending upon the cell line. The growth of 8 ovarian cell lines was stimulated in a dose-dependent manner when grown in the presence of exogenous TGF-alpha. Growth in 4 out of 5 of the cell lines capable of serum-free propagation was inhibited from 28 to 56% when cultured in medium containing a TGF-alpha neutralizing monoclonal antibody. Using selective amplification by polymerase chain reaction on cDNA substrates derived from mRNA, the expression of the EGF family of ligands (EGF, TGF-alpha, amphiregulin, crypto) and receptors (EGF-R, c-erbB-2) has been examined in three ovarian carcinoma cell lines and three samples of normal ovarian surface epithelium (OSE). Each carcinoma cell line expressed both receptors, and TGF-alpha, while two expressed amphiregulin, and one produced EGF. Conversely, the OSE cells appear to express crypto only. The initial phenotyping studies after messenger amplification are nearly complete so as to quantify the level of expression of this family of ligands and receptors. These results document that TGF-alpha is an autocrine growth factor for cell lines derived from ovarian cancers of epithelian origin, and suggest a potential role for TGF-alpha in the pathogenesis or progression of the disease. In addition, analysis by RNA phenotyping for other members of the EGF family suggest differential expression between normal and malignant ovarian epithelium.
