Oncogenic Gαq Signaling Remodels the Tumor Surfaceome and Rewires Intracellular Networks in Uveal Melanoma Models

Dysregulated G protein-coupled receptor (GPCR) signaling is increasingly implicated as an important driver for oncogenesis. Uveal melanoma (UM) represents a highly metastatic intraocular malignancy primarily driven by activating mutations in G protein family members Gαq/11. Although Tebentafusp, the first FDA-approved bi-specific T-cell engager for UM, improves survival, its activity is restricted to specific human leukocyte antigen (HLA) alleles, highlighting the need to identify broadly expressed targetable proteins for immunotherapeutic strategies. Here we aimed to define surfaceome and phospho-signaling signatures associated with oncogenic Gαq-signaling.

Heterologous and UM in vitro systems were used to interrogate Gαq-driven changes. HEK293T cells were transfected with wild-type Gαq or the oncogenic Gαq (R183Q) mutant, with surface marker profiles quantified by flow cytometry. Complementary immunophenotyping was performed in the Gαq-mutant UM cell line MP46 and Gα11-mutant line MP41. Kinase phosphorylation was assessed in control and Gαq mutant conditions followed by effect size estimation (Hedges' g), Welch's t-test, principal component analysis, and Spearman correlation-based network analysis of surface and phosphoprotein readouts.

Hyperactive Gαq in HEK293T cells induced graded remodeling of surface protein profiles, including reduced CD56 (NCAM) and CD49c (ITGA3) expression. Similarly, in UM models, MP46 versus MP41 had limited expression of CD56 and CD49c. Moreover, phospho kinase profiling and network analysis identified altered surface-phosphoprotein relationships, including a CD56-p70 S6 kinase association.

These data provide new insights into Gαq-driven modulators of UM phenotype of relevance for studies of tumor-microenvironment interaction and metastasis.