Malignant melanoma is a disease with high mortality rate caused by rapid metastasis. Cell motility is physically and biochemically restricted by cadherin-mediated cell interactions and signalling pathways, and alterations in cadherin expression strongly correlate with E to N-cadherin switch as well as the metastasis and progression of tumours. Contrary to E-cadherin, N-cadherin plays an important role in stimulating processes of cell division, migration, differentiation and death. In this study we investigated the role of N-cadherin in proliferation and AKT, ERK, beta-catenin signalling pathway in human melanoma cells: WM793(VGP), WM115(VGP) from the primary tumor site, as well as Lu1205(lung) and WM266-4(skin) from metastatic sites. N-cadherin, pAKT(S473), β-catenin, pERK1/2(T202/Y204), cyclin D1, cyclin D3, cyclin-dependent kinases CDK4, CDK6, and p15, p16, p21, p27 inhibitors expression was determined by western blot analysis. The study on proliferation of cells was performed with the use of BrdU incorporation and crystal violet staining assays. Knock-out of N-cadherin gene expression by siRNA process reduced the expression of: pAKT(S473), pERK1/2(T202/Y204), betacatenin, cyclin D1, cyclin D3 , cyclin-dependent kinases CDK4, CDK6 while increasing expression of cell cycle inhibitors p21 and p27, and significantly decreased cell proliferation (50-70%). The collected data indicate that N-cadherin mediates the effect of cell cycle in G1 phase by AKT, β-catenin, and ERK signalling pathway. These results suggest that increased expression of N-cadherin significantly contributes to the increased invasive potential of melanoma cells. Silencing of N-cadherin arrests cell growth at G1 phase and inhibits the entry into S-phase which is of great importance as to its possible future use in cancer treatment.
Keywords: AKT, β-catenin, cell cycle, ERK, melanoma, N-cadherin, proliferation, siRNA, Malignant melanoma, tumours