Ectodomain Shedding of the Cell Adhesion Molecule Nectin-4 in Ovarian Cancer is Mediated by ADAM10 and ADAM17 [Membrane Biology]

We previously showed that the cell adhesion molecule Nectin-4 is overexpressed in ovarian cancer tumors and its cleaved extracellular domain can be detected in the serum of ovarian cancer patients. The ADAM proteases (A Disintegrin and Metalloproteinase) are involved in ectodomain cleavage of transmembrane proteins and ADAM17 is known to cleave Nectin-4 in breast cancer. However, the mechanism of Nectin-4 cleavage in ovarian cancer has not yet been determined. Analysis of ovarian cancer gene microarray data showed that higher expression of Nectin-4, ADAM10, and ADAM17 is associated with significantly decreased progression-free survival. We quantified Nectin-4 shedding from the surface of ovarian cancer cells after stimulation with lysophosphatidic acid (LPA). We report that ADAM17 and ADAM10 cleave Nectin-4 and release soluble Nectin-4 (sN4). Small molecule inhibitors and siRNA knockdown of both ADAM proteases confirmed these results. In matched samples from eleven high-grade serous ovarian cancer patients, we detected 2-fold to 20-fold more sN4 in ascites fluid than serum. Co-incubation of ovarian cancer cells with ascites fluid increased sN4 shedding significantly, which could be blocked using a dual inhibitor of ADAM10 and ADAM17. Furthermore, we detected RNA for Nectin-4, ADAM10, and ADAM17 in primary ovarian carcinoma tumors, secondary omental metastases, and ascites cells isolated from serous ovarian cancer patients. In a signaling pathway screen, LPA increased phosphorylation of AKT, EGFR, ERK1/2, JNK1/2/3, and c-Jun. Understanding the function of Nectin-4 shedding in ovarian cancer progression is critical to facilitate its development as both a serum biomarker and a therapeutic target for ovarian cancer.

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