Production of Growth Factors by Normal Human Mammary Cells in Culture

Abstract

Recent evidence from several laboratories has demonstrated that human breast cancer cell lines produce a variety of polypeptide growth factors, including platelet derived growth factor (PDGF), insulin like growth factor (IGFI), transforming growth factors alpha and beta (TGFα and TGFβ), mammary-derived growth factor I (MDGFI), mammary-derived growth factor II (MDGFII), gastrin releasing peptide (GRP), human mammary tumor growth factor (h.MTGF) and epidermal growth factor (EGF). It has been assumed that production of the factors was a pathological phenomenon, one accompanying neoplastic transformation. However, we and others have shown that most of these are normal components of milk. Consequently, we postulated that the tumor cell-derived factors might be normal glandular secretory products.