α-Catulin downregulates E-cadherin and promotes melanoma progression and invasion

Metastasis is associated with poor prognosis for melanoma responsible for about 90% of skin cancer-related mortality. To metastasize, melanoma cells must escape keratinocyte control, invade across the basement membrane and survive in the dermis by resisting apoptosis before they can intravasate into the circulation. α-Catulin (CTNNAL1) is a cytoplasmic molecule that integrates the crosstalk between nuclear factor-kappa B and Rho signaling pathways, binds to β-catenin and increases the level of both α-catenin and β-catenin and therefore has potential effects on inflammation, apoptosis and cytoskeletal reorganization. Here, we show that α-catulin is highly expressed in melanoma cells. Expression of α-catulin promoted melanoma progression and occurred concomitantly with the downregulation of E-cadherin and the upregulation of expression of mesenchymal genes such as N-cadherin, Snail/Slug and the matrix metalloproteinases 2 and 9. Knockdown of α-catulin promoted adhesion to and inhibited migration away from keratinocytes in an E-cadherin-dependent manner and decreased the transmigration through a keratinocyte monolayer, as well as in Transwell assays using collagens, laminin and fibronectin coating. Moreover, knockdown promoted homotypic spheroid formation and concomitantly increased E-cadherin expression along with downregulation of transcription factors implicated in its repression (Snail/Slug, Twist and ZEB). Consistent with the molecular changes, α-catulin provoked invasion of melanoma cells in a three-dimensional culture assay by the upregulation of matrix metalloproteinases 2 and 9 and the activation of ROCK/Rho. As such, α-catulin may represent a key driver of the metastatic process, implicating potential for therapeutic interference.