Palmitoylation of GNAQ/11 is critical for tumor cell proliferation and survival in GNAQ/11-mutant uveal melanoma

More than 85%of patients with uveal melanoma(UM)carry a GNAQ or GNA11 mutation at a hotspot codon(Q209)that encodes G proteinαsubunit q/11 polypeptides(Gα_(q/11)).GNAQ/11 relies on palmitoylation for membrane association and signal transduction.Despite the palmitoylation of GNAQ/11 was discovered long before,its implication in UM remains unclear.Here,results of palmitoylation-targeted mutagenesis and chemical interference approaches revealed that the loss of GNAQ/11 palmitoylation substantially affected tumor cell proliferation and survival in UM cells.Palmitoylation inhibition through the mutation of palmitoylation sites suppressed GNAQ/11^(Q209L)-induced malignant transformation in NIH3T3 cells.Importantly,the palmitoylation-deficient oncogenic GNAQ/11 failed to rescue the cell death initiated by the knock down of endogenous GNAQ/11 oncogenes in UM cells,which are much more dependent on Gα_(q/11) signaling for cell survival and proliferation than other melanoma cells without GNAQ/11 mutations.Furthermore,the palmitoylation inhibitor,2-bromopalmitate,also specifically disrupted Gα_(q/11) downstream signaling by interfering with the MAPK pathway and BCL2 survival pathway in GNAQ/11-mutant UM cells and showed a notable synergistic effect when applied in combination with the BCL2 inhibitor,ABT-199,in vitro.The findings validate that GNAQ/11 palmitoylation plays a critical role in UM and may serve as a promising therapeutic target for GNAQ/11-driven UM.