Partial purification of transforming growth factors from human milk.
Crude, delipidated milk and the acid:ethanol extracts of primary human breast tumors contain several activities that biologically resemble transforming growth factors (TGFs) in that they promote the anchorage-independent growth of normal rat kidney and Mm5mt/c1 mouse mammary tumor cells in soft agar. Three major TGF species with isoelectric points (pl) of about 4.0, 6.0-6.5, and 7.0 have been detected in both tumors and milk. The pl 4.0 species from milk has been purified about 10,000-fold by isoelectric focusing and high-performance liquid chromatography. This species, designated milk-derived growth factor II (MDGFII), coelutes from gel filtration columns with an authentic human epidermal growth factor standard when using a low ionic strength eluting buffer. However, on the same column, MDGFII is completely resolved from human epidermal growth factor with high ionic strength eluting buffers. Nevertheless, MDGFII purified by the latter technique still competes with 125I-epidermal growth factor for receptor binding to A431 cell membranes. Additionally the TGF activity of MDGFII present in the pl 4.0 fraction of milk is markedly inhibited by anti-epidermal growth factor receptor antibody preparations. Consequently MDGFII appears to be an alpha-TGF. MDGFII is a pepsin-sensitive, disulfide reducing agent-sensitive, heat-stable protein that may be physiologically important for the mammary gland or the neonate.
D000818:Animals; D001943:Breast Neoplasms / Q000032:analysis*; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D002851:Chromatography, High Pressure Liquid; D004815:Epidermal Growth Factor / Q000032:analysis / Q000378:metabolism; D066246:ErbB Receptors; D005260:Female; D006133:Growth Substances / Q000145:classification / Q000302:isolation & purification*; D006801:Humans; D007526:Isoelectric Point; D008325:Mammary Neoplasms, Experimental / Q000473:pathology; D051379:Mice; D008894:Milk Proteins / Q000302:isolation & purification; D008895:Milk, Human / Q000032:analysis*; D010455:Peptides / Q000145:classification / Q000302:isolation & purification*; D011956:Receptors, Cell Surface / Q000378:metabolism; D015291:Transforming Growth Factors
D006133:Growth Substances; D008894:Milk Proteins; D010455:Peptides; D011956:Receptors, Cell Surface; D004815:Epidermal Growth Factor; D015291:Transforming Growth Factors; D066246:ErbB Receptors