Characterization of growth factors in human ovarian carcinomas

Epidermal growth factor (EGF)-like factors with EGF competing and cell growth stimulating activity were investigated in malignant and nonmalignant tissues. About 37% of ovarian carcinomas present an increased factor activity between 9.0 and 19.3 ng EGF units/mg protein. In one tumor 175.0 ng EGF units/mg protein were found. In extracts of nonmalignant tissues, the factor concentration was about 1.0-6.4 ng EGF units/mg protein. Isoelectric focusing was performed to characterize these factors. In normal ovaries and ovarian carcinomas, factors with EGF competing activity focus at pH 8.0-9.0, pH 5.7-6.3, and pH 3.6-4.9. In ovarian carcinomas, an additional peak with EGF competing and cell growth stimulating activity was found between pH 6.5 and 7.2. Similar results could be achieved in other malignant tissues investigated. These data indicate the presence of EGF-like factors. EGF itself focuses at pH 4.6 (G. Carpenter and S. Cohen, Annu. Rev. Biochem., 48: 193-216, 1979). Specific EGF binding was determined in 12 ovarian carcinomas. In five of these cases EGF receptors could be detected. In the EGF receptor positive carcinomas, the content of EGF-like growth factors varied between 0 and 9 ng EGF units/mg protein. In EGF receptor negative cases, the content of EGF-like growth factors varied between 0 and 19.3 ng EGF units/mg protein. The clinical data of 19 patients are also demonstrated.