GNA15 as a regulator of tumor-immune crosstalk: oncogenic signaling, microenvironmental remodeling, and implications for targeted immunotherapy.

GNA15 is a Gαq-family G protein whose physiological expression is largely restricted to hematopoietic cells. Nevertheless, aberrant upregulation has been reported in six histologically distinct malignancies, with elevated expression consistently associated with adverse clinical outcomes. Unlike the ubiquitously expressed Gαq and Gα11 paralogs, GNA15 exhibits an expanded receptor-coupling repertoire that extends beyond their canonical GPCR interactions. Despite the diversity of tumor types, its oncogenic functions consistently converge on four major signaling programs: MAPK activation, BTK-dependent signaling, AMPK-mediated metabolic reprogramming, and EMT-associated cellular plasticity. Each of these mechanisms has been functionally validated in at least one cancer model. Across multiple malignancies, elevated GNA15 expression is associated with increased M2 macrophage infiltration, immunosuppressive transcriptional signatures, and poor patient outcomes. These associations remain correlative, however, as no study has yet demonstrated that GNA15 signaling directly drives these immune-related phenotypes. Nevertheless, existing evidence suggests that GNA15-associated changes in the tumor microenvironment could influence the effectiveness of immune checkpoint blockade and may also bear on the success of newer approaches such as engineered cellular therapies, bispecific antibodies, and antibody-drug conjugates. By contrast, the evidence supporting its oncogenic function is considerably more robust: genetic silencing of GNA15 consistently attenuates malignant phenotypes across four independent tumor models, providing the strongest evidence for its therapeutic relevance. Its proposed immunological role, by comparison, remains hypothesis-generating, as it is derived exclusively from correlative observations and has not been evaluated in immune-competent experimental systems. Overall, GNA15 represents a biologically plausible yet clinically unvalidated link between GPCR signaling and tumor-immune regulation. At present, the available evidence supports its development as a prognostic biomarker; whether it also has predictive value for immunotherapy response remains untested and requires prospective validation.