[Detection of epidermal growth factor-like factors in various skin tumors]

EGF-like factors (EGF-F) in tissue extracts make use of the EGF receptor system (EGF-R) in order to transmit biological signals. EGF-F, which partly show transforming activities, can be detected with the help of an EGF receptor assay. We measured the EGF concentrations in extracts of 25 benign, 5 semi-malignant, and 13 malignant skin tumors, as well as in 5 biopsies of normal skin. The highest amounts of EGF-F were found in malignant melanoma (10 ng/mg) and in squamous cell carcinoma (7 ng/mg). The EGF-F concentrations in benign and semi-malignant tumors, in contrast, were similar to those found in normal skin (up to 4 ng/mg). Isoelectric focusing (IEF) revealed that the activity of EGF-F malignant tumors consists of various components.