Separation of transforming growth factors TGF alpha and TGF beta during chromatographic purification of extracts from mouse C-234 tumors.

Polypeptide transforming growth factors: TGF alpha and TGF beta were isolated and separated from acidic ethanol extracts of mouse C-243 tumors. The purification of the acid-soluble extract was achieved by Bio-Gel P-60 filtration chromatography, followed by CM-Sepharose CL-6B ion exchange, Bio-Gel P-10 filtration, and dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). At the Bio-Gel P-10 purification step, TGF alpha was separated from TGF beta. TGF alpha stimulated mouse Balb/c-3T3, rat NRK-49F and human A549 cells to form colonies in soft agar, and competed with 125I-labeled epidermal growth factor (EGF) for binding to human placenta membrane receptors. Over 40,000-fold SDS-PAGE-purified TGF beta had an Mr of 25,000. Unlike TGF alpha, TGF beta stimulated the clonal growth of NRK fibroblasts only in the presence of the suboptimal amounts of EGF (0.5 ng/ml). TGF beta significantly inhibited the anchorage-independent growth of malignant human lung carcinoma A549 cells, and in the radioreceptor assay with 125I-EGF it had no affinity to EGF receptors.