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ADAM10

PURPOSE: The a-disintegrin-and-metalloprotease (ADAM) family proteins are widely expressed in the different layers of the retina throughout development. The effect of ADAM proteins on the epithelial-to-mesenchymal transition (EMT) in proliferative vitreoretinopathy (PVR) or AMD is yet to be elucidated. In this study we used Epstein-Barr virus (EBV)-transformed adult retinal pigment epithelial (ARPE) cells to investigate how sorafenib, a multikinase inhibitor, modulates ADAM proteins to control EMT. METHODS: epithelial to mesenchymal transition and related mechanisms in EBV-infected ARPE cells were determined by RT-PCR, Western blot, invasion assay, ELISA assay, and gene silencing with siRNA. RESULTS: mesenchymal-like ARPE/EBV cells exhibited considerably increased cellular migration and invasion compared with ARPE cells and produced EMT-related cytokines. Sorafenib significantly inhibited production of TGF-beta1, VEGF, IL-6, IL-8, MCP-1, and TNF-alpha and blocked the activation of migration-related signaling molecules, such as HIF-1alpha, p-STAT3, MMP2, and Ang-1. The expression of mature ADAM10, ADAM17, and cleaved Notch 1 proteins in ARPE/EBV cells was downregulated after treatment with sorafenib through the regulatory activity of nardilysin (NRD-1). Gene silencing of NRD-1 in ARPE/EBV cells attenuated secretion of EMT-related cytokines and expression of ADAM10 and 17 and upregulated epithelial markers. CONCLUSIONS: Sorafenib controls the mesenchymal characteristics of EBV-infected ARPE cells. Nardilysin and ADAM family proteins might be new targets for the prevention or control of EMT in retinal diseases.

Toll-like receptor 4 (TLR4) activation is a key contributor to the carcinogenesis of colon cancer. Overexpression of galectin-1 (Gal-1) also correlates with increased invasive activity of colorectal cancer. Lactate production is a critical predictive factor of risk of metastasis, but the functional relationship between intracellular lactate and Gal-1 expression in TLR4-activated colon cancer remains unknown. In this study, we investigated the underlying mechanism and role of Gal-1 in metastasis and invasion of colorectal cancer (CRC) cells after TLR4 stimulation. Exposure to the TLR4 ligand lipopolysaccharide (LPS) increased expression of Gal-1, induced EMT-related cytokines, triggered the activation of glycolysis-related enzymes, and promoted lactate production. Gene silencing of TLR4 and Gal-1 in CRC cells inhibited lactate-mediated epithelial-mesenchymal transition (EMT) after TLR4 stimulation. Gal-1-mediated activation of a disintegrin and metalloproteinase 10 (ADAM10) and ADAM 17 increased the invasion activity and expression of mesenchymal characteristics in LPS-activated CRC cells. Conversely, inhibition of ADAM10 or ADAM17 effectively blocked the generation of lactate and the migration capacity of LPS-treated CRC cells. Thus, the TLR4/Gal-1 signaling pathway regulates lactate-mediated EMT processes through the activation of ADAM10 and ADAM17 in CRC cells.

The activation of phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) is critical for the induction of epithelial-mesenchymal transition (EMT) by growth factors, including insulin-like growth factor 1 (IGF-1). The activation of intracellular lipogenesis provides proliferative and survival signals for cancer cells. In this study, we investigated the connection between lipogenesis-related EMT processes and IGF-1-mediated PI3K p110 isoform activation in primary (SW480 cells) and metastatic (SW620) colon carcinoma cells. We also examined the underlying signaling pathway that promotes fatty acid synthesis in IGF-1-activated colon cancer cells. IGF-1 stimulation upregulated the expression of lipogenic enzymes as well as the activation of Nardilysin (N-arginine dibasic convertase, NRD1) and its downstream targets, a disintegrin and metalloproteases 10 (ADAM10) and ADAM17. The upregulation of the Lyn/Syk-mediated PI3K p110delta isoform in SW480 cells and the Lyn-dependent PI3K p110alpha isoform in SW620 cells triggered fatty acid production and cell motility in IGF-1-activated colon cancer cells. Pharmacological inhibition with A66 (PI3K p110alpha specific inhibitor) and CAL-101 (PI3K p110delta specific inhibitor) efficiently inhibited EMT in colon cancer cells by blocking the NRD1/ADAM family protein signaling pathway. Gene silencing of NRD1 and ADAM family proteins attenuated the generation of intracellular fatty acid and the migratory activity of colon cancer cells. Our results suggest that the different isoforms of the PI3K p110 subunit could be therapeutic targets for primary and metastatic colon cancer and that regulation of the NRD1/ADAM signaling pathway controls lipogenesis-mediated EMT in IGF-1-stimulated colon cancer cells.