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<sup>R24C/R24C</sup>, demonstrated to spontaneously develop melanoma.
Looking for the effectors of these antineoplastic functions, we identified ADAM9 and MMP7, two metalloproteases playing a pivotal role in melanoma progression, as direct targets of miR-126&126*.
Using RNAi this EGFR activation was further shown to depend on the metalloproteases ADAM9 and ADAM17 in SCC-9 cells. cDNA array hybridization and RT-PCR analysis showed overexpression of a Disintegrin and a Metalloproteases (ADAMs) and EGF family proligands in melanoma cell lines.
However, we observed downregulation of ADAM-9 mRNA expression upon culture of melanoma cells within 3-dimensional lattices composed of fibrillar type I collagen, whereas culture within gels consisting of the polysaccharide alginate did not alter transcript levels.
RNA analysis of melanoma cell lines with different invasive abilities showed ADAM-9 expression in varying amounts in all cell lines, independent of their invasive and metastatic capacities.