Growth hormone (GH) modulation of Epidermal growth factor (EGF) signalling in human mammary epithelial cells

This study demonstrates crosstalk between Growth Hormone (GH) and Epidermal Growth Factor (EGF) in two different breast cancer cell lines. Long-term modification of cell viability and the ERK1/2 and AKT pathways was only detected in MDA-231 cells. By simultaneous treatment with GH and EGF, the interaction between GH and EGF in MCF-7 cells could be transiently abrogated by GH-pre-treatment. Co-treatment with GH and EGF diminished cell viability in MCF-7 and MDA-231 cells. Furthermore, a direct influence between GH and EGF signaling resulted in less ERK phosphorylation in MCF-7 cells, whereas in MDA-231 cells less AKT phosphorylation could be observed. EGFR-down regulation due to GH is a potential reason but keeps to be elucidated.