Purification and characterization of a human mammary tumor-derived growth factor

A growth factor has been purified to homogeneity from human mammary tumors. The human mammary tumor-derived growth factor (h.MTGF) has a molecular weight of 16,000 and an isoelectric point of 8.0 and is sensitive to heat, trypsin digestion, acid, and reduction. h.MTGF was purified to homogeneity using carboxymethylcellulose 52, heparin-Sepharose, and copper-Sepharose affinity chromatography. The stimulation of proliferation in cultured rabbit fetal chondrocytes was used as the principal bioassay. Purified h.MTGF was also mitogenic for bovine corneal endothelial cells, human fibroblasts, and a human breast cancer cell line, T-47D. It is postulated that h.MTGF may play a role in the fibrovascular changes of malignant breast tumors and promote the autonomous growth of the neoplastic cell population.