Mutant GNAQ promotes cell viability and migration of uveal melanoma cells through the activation of Notch signaling.

The occurrence of guanine nucleotide binding protein (G protein), q polypeptide (GNAQ) mutations has been found to be high in the majority of uveal melanomas. However, the underlying molecular mechanism of GNAQ mutations in modulating uveal melanoma is poorly understood. The aim of the present study was to investigate the role and underlying mechanism of mutant GNAQ in the regulation of cell viability and migration of uveal melanoma cells. Uveal melanoma cells containing mutant GNAQ were transfected with scrambled or GNAQ small-interfering RNA. Compared with the control, GNAQ knockdown markedly inhibited cell viability and migration. However, tumor cells without GNAQ mutations exhibited enhanced viability and migration following transfection with HA-GαqQL. Additionally, GNAQ knockdown significantly downregulated the expression of Jag-1 (Notch ligand), Notch intracellular domain and Hes-1 (Notch target gene) in uveal melanoma cells. Conversely, the GNAQ overexpression promoted their expression. Cell viability and migration induced by GNAQ was significantly inhibited following treatment with 5 µmol/l MRK003, a Notch signaling inhibitor. Furthermore, the transfection of human influenza hemagglutinin A epitope (HA)-GαqQL into tumor cells caused Yes-associated protein (YAP) dephosphorylation and nuclear translocation, which stimulated the expression of Jag-1 and Hes-1. Positive correlations were observed between the GNAQ and Jag-1 mRNA levels and between the GNAQ and Hes-1 mRNA levels. However, no positive correlation was observed between the GNAQ and YAP mRNA levels. The results suggested that GNAQ mutation induced viability and migration of uveal melanoma cells via Notch signaling activation, which is mediated by YAP dephosphorylation and nuclear translocation.