Angiogenesis, Metastasis, and the Cellular Microenvironment Copper Modulates Zinc Metalloproteinase-Dependent Ectodomain Shedding of Key Signaling and Adhesion Proteins and Promotes the Invasion of Prostate Cancer Epithelial Cells

A disintegrin and metalloproteinases (ADAMs) and matrix metalloproteinases (MMPs) are zinc metalloproteinases (ZMPs) that catalyze the "ectodomain shedding" of a range of cell surface proteins including signaling and adhesion molecules. These "sheddases" are associated with the invasion and metastasis of a range of cancers. Increased serum and tumor tissue levels of copper are also observed in several cancers, although little is known about how the metal might promote disease progression at the molecular level. In the current study, we investigated whether copper might regulate the ectodomain shedding of two key cell surface proteins implicated in the invasion andmetastasis of prostate cancer, theNotch ligand Jagged1 and the adhesionmolecule E-cadherin, andwhether the metal was able to influence the invasion of the prostate cancer epithelial cell line PC3. Physiological copper concentrations stimulated the ZMP-mediated proteolysis of Jagged1 andE-cadherin in cell culturemodels, whereas other divalent metals had no effect. Copper-mediated Jagged1 proteolysis was also observed following the pretreatment of cells with cycloheximide and in a cell-free membrane system, indicating a posttranslational mechanism of sheddase activation. Finally, the concentrations of copper that stimulated ZMP-mediated protein shedding also enhanced PC3 invasion; an effect that could be negated using a sheddase inhibitor or copper chelators. Collectively, these data implicate copper as an important factor in promoting prostate cancer cell invasion and indicate that the selective posttranslational activation of ZMP-mediated protein shedding might play a role in this process. Mol Cancer Res; 10(10); 1282–93. 2012 AACR.