Oncostatin M and leukemia inhibitory factor regulate the growth of normal human breast epithelial cells.

We have previously reported the inhibitory effects of oncostatin M (OSM) and leukemia inhibitory factor (LIF) on the proliferation of breast cancer cell lines. In this study, we examined the action of OSM and LIF on normal, non-malignant human breast epithelial cells (HBECs). We demonstrated expression of three components of the OSM receptor; gp130, the leukemia inhibitory factor receptor (LIFRbeta) and the OSM specific receptor (OSMRbeta). Treatment of the normal HBECs with OSM and LIF resulted in inhibition of proliferation, even in the presence of the breast mitogen, epidermal growth factor (EGF), which is required for HBEC growth. The inhibition was associated with a reduction of cells in the S-phase of the cell cycle and an accumulation of cells in G0/G1. These results suggest a previously unrecognised physiological role for these growth factors in the regulation of normal breast epithelium.