Engineering of Specific Tissue Inhibitors to Block ADAM Type Metalloprotease-Mediated Mammary Neoplasia

摘要

Mammary tumors derive from mammary epithelial cells that lost the control for both cell growth and differentiation. Activation of a G protein coupled receptor (GPCR) transactivates the EGF receptor (EGFR) growth signal by inducing metalloprotease dependent release of the EGFR ligand HB-EGF. Here we demonstrated that expression of a membrane bound ADAM Kuzbanian (KUZ) in COS-7 cells stimulates the transactivation of EGFR by bombesin, while a dominant negative form of KUZ (DNK), which lacks the protease domain blocked endogenous protease mediated tranactivation. This transactivation process was very sensitive to the inhibitors of ADAM type metalloprotease, the EGFR autophosphorylation, and HG-EGF. The role of KUZ in this trans activation appeared to be specific, since evolutionarily close related ADAM TACE did not elicit the transactivation. These results show that KUZ is the physiologically relevant metalloprotease that mediates the transactivation of EGFR by GPCR through enhancing the supply of HB-EGF. To investigate the effect of blocking KUZ in mammary neoplasia, transgenic mice conditionally expressing DNK, mutant TIMP3 and activated Notch4 have been constructed.