부산대학교 도서관

Simple Summary: While the treatment of melanoma was revolutionized about a decade ago by the introduction of immunotherapies and targeted therapies, advanced melanoma remains a therapeutic challenge. Here we demonstrate a cross-talk between a checkpoint protein, PD-L1, and a receptor tyrosine kinase (RTK), MET. These findings open the possibility of combining selective inhibitors of these proteins to achieve synergistic efficacy in the treatment of melanoma. Melanoma is the leading cause of death from cutaneous malignancy. While targeted therapy and immunotherapy with checkpoint inhibitors have significantly decreased the mortality rate of this disease, advanced melanoma remains a therapeutic challenge. Here, we confirmed that interferon-gamma (IFN-γ)-induced PD-L1 expression in melanoma cell lines. This increased expression was down-regulated by the reduction in phosphorylated STAT3 signaling via MET tyrosine kinase inhibitor treatment. Furthermore, immunoprecipitation and confocal immunofluorescence microscopy analysis reveals MET and PD-L1 protein–protein interaction and colocalization on the cell surface membrane of melanoma cells. Together, these findings demonstrate that the IFN-γ-induced PD-L1 expression in melanoma cells is negatively regulated by MET inhibition through the JAK/STAT3 signaling pathway and establish the colocalization and interaction between an RTK and a checkpoint protein in melanoma cells. [ABSTRACT FROM AUTHOR]