UV-induced EGFR signal transactivation is dependent on proligand shedding by activated metalloproteases in skin cancer cell lines
Article first published online: 2 SEP 2008
Copyright © 2008 Wiley-Liss, Inc.
International Journal of Cancer
Volume 124, Issue 3, pages 531–539, 1 February 2009
How to Cite
Singh, B., Schneider, M., Knyazev, P. and Ullrich, A. (2009), UV-induced EGFR signal transactivation is dependent on proligand shedding by activated metalloproteases in skin cancer cell lines. Int. J. Cancer, 124: 531–539. doi: 10.1002/ijc.23974
- Issue published online: 18 NOV 2008
- Article first published online: 2 SEP 2008
- Accepted manuscript online: 2 SEP 2008 12:00AM EST
- Manuscript Accepted: 19 AUG 2008
- Manuscript Received: 27 FEB 2008
- EGFR signal transactivation;
Exposure to extensive ultraviolet (UV) rays is a major cause of skin cancer, which is thought to be initiated by DNA mutations. Members of the epidermal growth factor receptor (EGFR) family are important in various pathophysiologic processes like cancer and are shown to be phosphorylated upon UV exposure. Here we show that EGFR phosphorylation by modest UV doses is dependent on metalloprotease activity and resultant epidermal growth factor (EGF) family proligand shedding. This proligand cleavage releases the mature ligand, which then binds to and activates EGFR. We show that UV induced EGFR phosphorylation in transformed cell lines of melanocyte and keratinocyte origin, which was reduced upon preincubation with a broad-spectrum metalloprotease inhibitor, BB94. UV also activated EGFR downstream signaling via Erk and Akt pathways in a BB94-sensitive manner. Furthermore, using neutralizing antibodies we found that proligand amphiregulin was required for UV-induced EGFR activation in SCC-9 cells. Using RNAi this EGFR activation was further shown to depend on the metalloproteases ADAM9 and ADAM17 in SCC-9 cells. cDNA array hybridization and RT-PCR analysis showed overexpression of a Disintegrin and a Metalloproteases (ADAMs) and EGF family proligands in melanoma cell lines. Additionally, blocking EGFR signal transactivation by BB94 led to increased apoptosis in UV-irradiated cells. EGFR signal transactivation also led to increased stability of the DNA repair protein, PARP, under UV stress. Thus, both antiapoptotic and DNA repair pathways are activated simultaneously by EGFR signal transactivation. Together, our data provide novel insights into the mechanism of UV-induced EGFR activation, suggesting broad relevance of the UV-ADAM-proligand-EGFR-Erk/Akt pathway and its significance in skin cancer. © 2008 Wiley-Liss, Inc.