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ADAM17

The activity of a variety of extracellular signaling factors is tightly regulated by proteins containing A Disintegrin And a Metalloprotease domain (ADAM) metalloproteases through limited proteolysis. Thus, the identification of ADAM substrates may unveil novel components and mechanisms of cell signaling pathways. We report the identification of the transmembrane protein vasorin (VASN), a transforming growth factor-beta (TGFbeta) trap, as a substrate of ADAM17. The metalloprotease efficiently generates a soluble fragment encompassing the extracellular domain of VASN. Despite the importance of TGFbeta in normal development and tumor progression, the regulation of VASN is completely unknown. Here, we show that only the soluble form of VASN inhibits TGFbeta and that the secretion of VASN is tightly controlled by ADAM17. Hence, inhibition of ADAM17 leads to the upregulation of TGFbeta signaling. Adding a new level of complexity to the function of ADAM17, we finally show that, through the cleavage of VASN, the metalloprotease controls TGFbeta-mediated epithelial-to-mesenchymal transition.

BACKGROUND/AIMS: A disintegrin and metalloprotease (ADAM) 17 has been reported to be implicated in cancer cells invasion. Nevertheless, its potential role in lung adenocarcinoma has not been addressed clearly. METHODS: RT-PCR and Western blot were used to detect the expression of miR-326 and ADAM17 in lung adenocarcinoma samples (n=73). miR-326 mimics and inhibitor were tansfected in human A549 and SPCA1 cell lines. The transwell assay was used to detect the cell invasive ability. The regulation mechanism was evaluated by luciferase reporter assay. The markers of (epithelial-to-mesenchymal transition) EMT were detected by using Western blot assay. RESULTS: We found increased expression of ADAM17 in lung adenocarcinoma and cell lines. In vitro, up-regulation of ADAM17 promoted cells invasion, while silencing of ADAM17 inhibited cells invasion. Meanwhile, ADAM17 could affect the markers of EMT. Furthermore, we confirmed that ADAM17 is a target of miR-326, which is involved in EMT and cells invasion. CONCLUSIONS: These findings revealed that ADAM17, a target of miR-326, promoted EMT-induced cells invasion in lung adenocarcinoma.CI - (c) 2015 S. Karger AG, Basel.

Although a disintegrin and metalloproteinase-17 (ADAM17) overexpression has been demonstrated in numerous human tumors including gastric cancer, its role in gastric cancer development remains to be clarified. In the present study, we identify that ADAM17 activates TGF-beta/Smad signaling to promote epithelial-mesenchymal transition (EMT) in gastric cancer cells. We found that ADAM17 promotes proliferation, migration and invasion in gastric carcinoma cells. Subsequently, we revealed that silencing ADAM17 induces the expression of epithelial marker of E-cadherin and downregulates expression of mesenchymal markers including N-cadherin, vimentin and Snail in MGC803 and MKN45 cells, whereas ADAM17 overexpression reverses these changes in BGC823 and HGC27 cells. Furthermore, ADAM17 knockdown significantly inhibits the expression of TGF-beta and its downstream signaling molecules p-Smad2 and p-Smad3 in MGC803 and MKN45 cells. Consistently, ADAM17 overexpression reversed these changes in BGC823 and HGC27 cells. These results suggest that ADAM17 promotes epithelial-mesenchymal transition via the TGF-beta/Smad pathway. Collectively, the present study demonstrates that ADAM17 plays a critical role in the development of gastric cancer and provides a potential therapeutic target for gastric cancer.

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.

OBJECTIVES: Colorectal cancer is one of the most common malignancies both in men and women. Owing to metastasis and resistance, the prognosis of colorectal cancerCRC patients remains extremely poor with chemotherapy. A disintegrin and metalloproteinase 17 (ADAM17) induces the activation of Notch pathway and contributes to the chemoresistance. This study aimed to discover a novel ADAM17 inhibitor and investigate the chemosensitization effect. MATERIALS AND METHODS: Pharmacophore model, western blot and enzymatic assay were used to discover ZLDI-8. Cell proliferation was determined by MTT and colony formation assay. Cell migratory and invasive ability were determined by wound healing scratch and transwell assay. Immunofluorescence images and western blot analysed the expression of Notch or epithelial-mesenchymal transition (EMT) pathway markers. Xenografts were employed to evaluate the chemosensitization effect of ZLDI-8 in vivo. RESULTS: We found that ZLDI-8 cell-specifically inhibited the proliferation of CRC, and this effect was due to abrogation of ADAM17 and Notch pathway. Meanwhile, we reported for the first time that ZLDI-8 synergistically improved the anti-tumour and anti-metastasis activity of 5-fluorouracil or irinotecan by reversing Notch and EMT pathways. Interestingly, in vivo studies further demonstrated that ZLDI-8 promoted the anti-tumour effect of 5-fluorouracil through Notch and EMT reversal. CONCLUSIONS: A novel ADAM17 inhibitor ZLDI-8 may be a potential chemosensitizer which sensitized CRC cells to 5-fluorouracil or irinotecan by reversing Notch and EMT pathways.CI - (c) 2018 John Wiley & Sons Ltd.