More than 85% of patients with uveal melanoma (UM) carry a GNAQ or GNA11 mutation at a hotspot codon (Q209) that encodes G protein α subunit 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.
Humans ; Mice ; Animals ; Lipoylation ; NIH 3T3 Cells ; Uveal Neoplasms/genetics* ; Melanoma/genetics* ; Cell Proliferation ; Proto-Oncogene Proteins c-bcl-2 ; GTP-Binding Protein alpha Subunits, Gq-G11/genetics*