Characterization and partial purification of human epithelial transforming growth factor

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Abstract
A polypeptide growth factor has been partially purified from medium conditioned by the human adrenocortical carcinoma cell line SW13. This factor, designated h-TGFe, stimulates anchorage-independent growth of the SW13 cells. Similar activity was observed in human milk, and in conditioned media from seven of 14 epithelial cell lines. The SW13-derived activity is stable to low pH and 8M urea but labile to dithiothreitol and 2% sodium dodecyl sulfate. Human TGFe does not bind to heparin and fails to stimulate growth of endothelial cells in monolayer culture. The apparent molecular weight of h-TGFe is 59k by size exclusion chromatography in the presence of 8M urea and the activity binds strongly to cation exchangers. The activity elutes at 15–30% acetonitrile from a C18 reversephase column and has been partially purified by using a four-step chromatographic procedure. TGFe appears to be a novel growth factor produced by many epithelial cells and tissues.