A clonogenic assay revealed that concentrations of TGF-alpha greater than 10(10) M induced a significant increase in colony formation, indicating TGF-alpha to be a breast cancer cell growth factor.
Estrogen receptor (ER)-negative MDA-231 human breast cancer cells have been shown to secrete high concentrations of several growth factors including transforming growth factor-alpha and insulin-like growth factor I, which could have important autocrine or paracrine growth regulatory functions and, additionally, could explain the rapid autonomous growth of these cells.
Expression of transforming growth factor alpha and its messenger ribonucleic acid in human breast cancer: its regulation by estrogen and its possible functional significance.
We describe studies on human breast cancer in which it is shown that specific growth factors (IGF-I, TGF alpha, PDGF) are secreted by human breast cancer cells and likely to be involved in tumor growth and progression.