The HLA-DR mediated signalling increases the migration and invasion of melanoma cells, the expression and lipid raft recruitment of adhesion receptors, PD-L1 and signal transduction proteins

The constitutive expression of Major Histocompatibility Complex (MHC) class II molecules is restricted to
professional Antigen-Presenting Cells (APCs), nevertheless almost 50% of melanomas express constitutively the
MHC class II molecules. Therefore, in two MHC class II constitutive expressing melanoma cell lines we studied
the signalling mediated by the HLA-DR molecules in the aim to understand the consequence of class II mediated
signalling on metastatic dissemination of melanoma. In particular, we reported that the HLA-DR mediated
signalling play a new role in melanoma progression, increasing the migration and invasion of melanoma cells.
Furthermore, we showed that the HLA-DR mediated signalling increases the expression and the lipid raft
localisation of class II molecules, PD-L1 receptor, Integrin and CAM adhesion receptors, FAK, AKT and STAT3
signalling proteins. We also showed that the HLA-DR mediated signalling increases the activation of FAK, AKT,
ERK, PKC and STAT3 signalling proteins and the expression of ILK, PAX, BRAF, ERK and PKC. Indeed, the results
showed suggest that the HLA-DR mediated signalling provides a platform useful to frustrate an effective antitumour
response and to increase melanoma migration and metastatic dissemination of this cancer.