Production of PDGF-like growth factor by breast cancer cell lines

The breast cancer cell line T47D produces factors which show mitogenic activity for 3T3 cells. Here we describe the partial purification of one of these factors and show that it has properties similar to platelet-derived growth factor (PDGF). The T47D factor is a heat-stable hydrophobic protein with a molecular weight of around 30,000, which inhibits the binding of 125I-EGF in a temperature-dependent manner. This 30 kd protein does not act synergistically with PDGF or fibroblast-derived growth factor (FDGF; also PDGF-like) in stimulating DNA synthesis; moreover, like these two factors, its mitogenic activity can be inhibited by an antiserum raised against human PDGF. A PDGF-like growth factor was also found in the serum-free medium of the breast cancer cell line MDA-MB-157. Since PDGF acts on mesenchymal cells, the production of PDGF-like growth factors by breast cancer cells suggests a basis for the intense stromal reaction seen in human breast cancers.