An oxidative stress mechanism mediates chelerythrine-induced heparin-binding EGF-like growth factor ectodomain shedding
✍ Scribed by Jayoung Kim; Jianqing Lin; Rosalyn M. Adam; Carolyn Lamb; Sharon Baughman Shively; Michael R. Freeman
- Book ID
- 102300341
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 318 KB
- Volume
- 94
- Category
- Article
- ISSN
- 0730-2312
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✦ Synopsis
Abstract
Regulated shedding of cell surface proteins is a mechanism for rapid activation of autocrine and paracrine signaling. Here we report that chelerythrine, a protein kinase C (PKC) inhibitor that possesses a variety of biological functions, is a potent inducer of heparin‐binding epidermal growth factor‐like growth factor (HB‐EGF) shedding from the cell surface. Chelerythrine induced a time‐ and dose‐dependent shedding of an HB‐EGF–alkaline phosphatase (HB‐EGF‐AP) fusion protein expressed in MC2 rat prostate epithelial cells. The soluble form of HB‐EGF‐AP bound to heparin and exhibited potent biological activity as measured by DNA synthesis assay. Chelerythrine‐induced HB‐EGF shedding was metalloproteinase‐(MMP‐) mediated because specific MMP antagonists inhibited shedding by ≥60%. Chelerythrine stimulated production of reactive oxygen species, and antioxidants prevented chelerythrine‐induced HB‐EGF shedding, suggesting that the production of intracellular peroxides is necessary for this event. Consistent with this possibility, antioxidant‐ and MMP‐inhibitable shedding was also demonstrated when hydrogen peroxide was used as an inducer. Although JNK/SAPK and p38 MAPK pathways were activated by chelerythine, these signaling mechanisms were not required to mediate the shedding event. However, JNK signaling was involved in chelerythrine‐stimulated apoptosis. Our results suggest that HB‐EGF shedding induced by chelerythrine is mediated predominantly via the production of reactive oxygen species. © 2004 Wiley‐Liss, Inc.