Secretion and dual regulation between epidermal growth factor and transforming growth factor-β1 in MDA-MB-231 cell line in 42-hour-long cultures

MDA-MB-231 is a breast cancer cell line which possesses large quantities of epidermal growth factor (EGF) receptors and specific high-affinity transforming growth factor-β1 (TGF-β1) receptors. We have established that these cells secrete constitutively measurable levels of EGF and TGF-β1 in conditioned medium. The constitutive secretion of EGF decreased over time in culture (42 h), while the constitutive secretion of TGF-β1 remained constant. TGF-β1 secretion in EGF-treated cells was lower than in controls (P<0.0001), but EGF concentrations were not modified after TGF-β1 supplement. We postulate that in MDA-MB-231 cell line there is a dual regulation between both growth factors.