Bile acid stress induces a nontranscriptional function of TFAP2A via stabilizing GOLIM4 to promote gallbladder cancer survival

Gallbladder cancer (GBC) is characterized by a bile acids (BAs)-rich microenvironment that imposes significant endoplasmic reticulum (ER) stress. While the transcription factor AP-2α (TFAP2A) is upregulated in GBC, its functional role in this specific stress context remains unknown. This study investigates how TFAP2A enables GBC cell adaptation and survival under BAs stress. TFAP2A expression was analyzed in the tissues of patients with GBC via RNA sequencing, immunohistochemistry, and western blot. In vitro functional assays and patient derived organoid models were used to assess TFAP2A’s role in GBC. Interaction partners were identified through astral data-independent acquisition (DIA) proteomics and confirmed by coimmunoprecipitation. Protein stability was evaluated using cycloheximide chase and ubiquitination assays. In vivo validation was performed using cell-derived and patient derived xenograft models. Golgi integrity and ER stress markers were analyzed by immunofluorescence and western blot. TFAP2A was highly expressed in GBC tissues and shows cytoplasmic accumulation correlating with BA levels. Under BAs stress, TFAP2A translocated to the cytoplasm, where it interacted with the Golgi protein GOLIM4 and stabilized it by inhibiting its ubiquitin-mediated degradation. This TFAP2A/GOLIM4 maintained Golgi structure and alleviated ER stress, as evidenced by downregulation of proapoptotic CHOP and upregulation of GRP78/BiP. Consequently, it promoted GBC cell survival, proliferation, and tumor growth. Knockdown of either TFAP2A or GOLIM4 suppressed malignant phenotypes and increased ER stress-induced apoptosis, both in vitro and in vivo. This study identified a novel, nontranscriptional function of TFAP2A in response to BAs stress. By stabilizing GOLIM4 and enhancing secretory capacity, the TFAP2A/GOLIM4 axis represented a UPR-independent adaptive pathway that confers a survival advantage to GBC cells. Targeting this interaction may offer a new therapeutic strategy for this aggressive malignancy.