Deletion of ADAM-9 in HGF/CDK4 mice impairs melanoma development and metastasis

Abstract

ADAM-9 is a metalloproteinase expressed in peritumoral areas by invading melanoma cells and by adjacent peritumoral stromal cells; however, its function in stromal and melanoma cells is not fully understood. To address this question in vivo in a spontaneous melanoma model, we deleted ADAM-9 in mice carrying the hepatocyte growth factor (Hgf) transgene and knock-in mutation Cdk4, demonstrated to spontaneously develop melanoma. Spontaneous melanoma arose less frequently in ADAM-9-deleted mice than in controls. Similarly reduced tumor numbers (although with faster growth kinetics) were detected upon induction of melanoma with 7,12-dimethylbenz[a]anthracene (DMBA). However, more lesions were induced at early time points in the absence of ADAM-9. Increased initial and decreased late tumor numbers were paralleled by altered tumor cell proliferation, but not apoptosis or inflammation. Importantly, significantly reduced lung metastases were detected upon ADAM-9 deletion. Using in vitro assays to address this effect mechanistically, we detected reduced adhesion and transmigration of ADAM-9-silenced melanoma cells to/through the endothelium. This implies that ADAM-9 functionally and cell autonomously mediates extravasation of melanoma cells. In vitro and in vivo we demonstrated that the basement membrane (BM) component laminin β3-chain is a direct substrate of ADAM-9, thus contributing to destabilization and disruption of the BM barrier during invasion. In in vitro invasion assays using human melanoma cells and skin equivalents, depletion of ADAM-9 resulted in decreased invasion of the BM, which remained almost completely intact, as shown by continuous staining for laminin β3-chain. Importantly, supplying soluble ADAM-9 to the system reversed this effect. Taken together, our data show that melanoma derived ADAM-9 autonomously contributes to melanoma progression by modulating cell adhesion to the endothelium and altering BM integrity by proteolytically processing the laminin-β3 chain. This newly described process and ADAM-9 itself may represent potential targets for anti-tumor therapies.

ADAM9 contributes to vascular invasion in pancreatic ductal adenocarcinoma

“…B), suggesting an integrin‐independent impact of ADAM9 on adhesion to these ECM substrates. Our results indicate a role of ADAM9 in mediating cell–matrix interactions and corroborate findings from earlier studies (Cominetti et al ., ; Giebeler et al ., ; Mygind et al ., ; Zigrino et al ., ).…”

“…Functional studies focusing on the role of ADAM9 in tumor biology are scarce. In the murine HGF/CDK4 melanoma model, ADAM9 contributes to tumor formation and metastatic load (Giebeler et al ., ). That study also highlighted a pivotal role of ADAM9 in trans‐endothelial migration, which was corroborated by other studies (English et al ., ; Micocci et al ., ).…”

“…ADAM9 is a proteolytically active member of the ADAM family of proteases and is described to be involved in various tumorigenic processes. It is upregulated in many solid tumors such as breast, brain, lung, gastric, skin, liver, and pancreas, and its expression levels often correlate with disease progression and a poor prognosis (Fan et al ., ; Giebeler et al ., ; Grutzmann et al ., ; Kim et al ., ; Kohga et al ., ; Kossmann et al ., ; O'Shea et al ., ). Multiple studies report the regulation of ADAM9 expression in tumors by supposedly tumor‐suppressive micro‐RNAs (Hamada et al ., ; Van Kampen et al ., ; Yuan et al ., ).…”

Loss of ADAM9 Leads to Modifications of the Extracellular Matrix Modulating Tumor Growth

“…Studies have shown that ADAM9 regulates cell–cell and cell–matrix interaction by binding to integrins, thereby leading to modulation of protease secretion and cell migration [ 11 , 12 , 13 ]. ADAM9 expression in melanoma cells contributes to melanoma progression modulating cell adhesion to the endothelium and altering basement membrane (BM) integrity by proteolytically processing the laminin-beta3 chain [ 14 ]. On the other hand, ADAM9 is found to be highly expressed in peritumoral areas where activated fibroblasts are found [ 14 , 15 ].…”

“…ADAM9 expression in melanoma cells contributes to melanoma progression modulating cell adhesion to the endothelium and altering basement membrane (BM) integrity by proteolytically processing the laminin-beta3 chain [ 14 ]. On the other hand, ADAM9 is found to be highly expressed in peritumoral areas where activated fibroblasts are found [ 14 , 15 ]. In these cells, altered expression of ADAM9 controls TIMP-1 expression and TNF-α/sTNFR1 pathway leads to modulation of melanoma cells proliferation and apoptosis [ 15 ].…”