ESR1 bridges GNGT1 to CLDN6 in promoting gastric cancer stemness and development

Abstract Gastric cancer (GC) remains a major global health burden, and the molecular determinants driving its progression are incompletely understood. In the present study, G protein subunit gamma transducin 1 (GNGT1) was identified as a clinically relevant oncogenic driver that promotes GC growth, stemness, and metastatic traits. Transcriptomic analysis of the stomach adenocarcinoma cohort of The Cancer Genome Atlas revealed that GNGT1 was significantly upregulated in GC tissues and that its high expression predicted markedly shorter overall (OS) and progression-free survival (PFS). These findings were validated at the protein level using immunohistochemistry on a GC tissue microarray, where elevated GNGT1 expression was associated with higher histological grade and poorer survival. Functional experiments demonstrated that GNGT1 silencing impaired cell proliferation, migration and clonogenicity, induced G 2 -phase arrest, enhanced apoptotic signaling and increased GC cells sensitivity to 5-fluorouracil. Mechanistically, interaction profiling and chromatin immunoprecipitation (ChIP) assays revealed that GNGT1 interacted with estrogen receptor 1 (ESR1) and contributed to maintaining its protein abundance and nuclear accumulation, thereby enhancing ESR1-dependent transcriptional activation of claudin 6 (CLDN6). Upregulated CLDN6 in turn promoted epithelial-mesenchymal transition (EMT) -associated signaling and elevated the expression of stemness markers Nanog and OCT4. Furthermore, the CLDN6/Wnt/β-catenin axis was implicated in GNGT1-mediated cancer stem cell properties, whereas pharmacological inhibition of Wnt/β-catenin signaling attenuated GNGT1-induced proliferation and migration. In vivo, GNGT1 depletion significantly reduced tumor growth, stemness marker expression and cell proliferation in xenograft models. Collectively, the present study identified GNGT1 as a previously unrecognized regulator of GC progression and stemness, acting via the GNGT1-ESR1-CLDN6-Wnt/β-catenin signaling axis to promote malignant phenotypes. These findings suggest that GNGT1 may represent a potential prognostic biomarker and therapeutic target in GC.