FCER1G: A multifunctional regulator in the immune microenvironment (Review).

The Fc fragment of IgE receptor 1G (FCER1G) gene encodes the Fc receptor common γ chain (FcRγ), a crucial adaptor protein in immune signaling. As the core subunit for multiple immune receptors, including high-affinity immunoglobulin E receptor, Fc fragment of IgG receptor and C-type lectin receptors, it regulates both innate and adaptive immune responses through its intracellular immunoreceptor tyrosine-based activation motif. Downstream effector functions include antibody-dependent cytotoxicity, phagocytosis and inflammatory cytokine production. Emerging evidence implicates FCER1G in diverse pathological conditions. In inflammatory diseases, epigenetic mechanisms strictly regulate its expression, driving inflammation by influencing immune cell polarization. In the context of cancer, it induces tumor progression by remodeling the immune microenvironment, inducing angiogenesis and enabling platelet-mediated metastasis. Notably, its prognostic value varies according to tissue origin. Although no current drugs directly target FCER1G, established agents such as aspirin may indirectly modulate its signaling. The present review aimed to summarize the current knowledge on the molecular structure, immune functions and regulatory mechanisms of FCER1G in inflammation and carcinogenesis, establishing a rationale for its potential use as a prognostic biomarker and therapeutic target.