April 30, 2004
Journal Article

Induced autocrine signaling through the epidermal growth factor receptor contributes to the response of mammary epithelial cells to tumor necrosis factor alpha

Abstract

In contrast to the well-known cytotoxic effects of tumor necrosis factor a (TNF) in many mammary cancer cells, we have found that TNF stimulates the proliferation and motility of human mammary epithelial cells (HMEC). Since the response of HMEC to TNF is similar to effects mediated by epidermal growth factor receptor (EGFR) activation, we explored the potential role of cross-talk through the EGFR signaling pathways in mediating cellular responses to TNF. Using a microarray enzyme-linked immunoassay, we found that exposure to TNF stimulated the dose-dependent shedding of the EGFR ligand transforming growth factor a (TGFa). Both proliferation and motility of HMEC induced by TNF was prevented either by inhibiting membrane protein shedding with a metalloprotease inhibitor, by blocking EGFR kinase activity, or by limiting ligand-receptor interactions with an antagonistic anti-EGFR antibody. EGFR activity was also necessary for TNF-induced release of MMP-9, a matrix metalloprotease thought to be an essential regulator of mammary cell migration. The cellular response to TNF was associated with a biphasic temporal pattern of extracellular signal-regulated kinase (ERK) phosphorylation, which was EGFR-dependent and modulated by inhibition of metalloprotease-mediated shedding. Significantly, the late phase of ERK phosphorylation, detectable within 4 hours after exposure, was blocked by the metalloprotease inhibitor batimastat, indicating that autocrine signaling through ligand shedding was responsible for this secondary wave of ERK activity. Our results indicate a novel and important role for metalloprotease activation and EGFR transmodulation in mediating the cellular response to TNF.

Revised: August 19, 2004 | Published: April 30, 2004

Citation

Chen W.U., R.L. Woodbury, L.E. Kathmann, L. Opresko, R.C. Zangar, H.S. Wiley, and B.D. Thrall. 2004. Induced autocrine signaling through the epidermal growth factor receptor contributes to the response of mammary epithelial cells to tumor necrosis factor alpha. Journal of Biological Chemistry 279, no. 18:18488-18496. PNNL-SA-40802.