Aldehyde oxidase 1 promotes gallbladder carcinogenesis through ROS-mediated activation of the Wnt/β-catenin pathway

Background: Aldehyde oxidase 1 (AOX1) is associated with various pathophysiological processes, including Cancer. Specifically, AOX1 has been demonstrated to have a close relationship with the progression of certain cancers. However, the expression, function, and mechanisms of action of AOX1 in gallbladder Cancer (GBC) remain unclear.

Methods: Utilizing immunohistochemistry, the study quantified the prevalence of AOX1 within tissues of gallbladder carcinoma and those of the surrounding non-cancerous regions. In vitro assays using gallbladder carcinoma cell lines with modulated AOX1 expression levels were performed to assess the protein's role in cell proliferation, migration, and invasion. Furthermore, flow cytometry techniques were harnessed to determine the influence of AOX1 on the content of Reactive Oxygen Species (ROS) in these cells. Additionally, the expression of epithelial-mesenchymal transition (EMT) markers and the Wnt/β-catenin signaling pathway markersin cells with varied AOX1 expression, detected through Western blot analyses. An in vivo xenograft model involving athymic mice was implemented to explore the influence of AOX1 on gallbladder tumor growth, with Western blot analysis applied to measure EMT marker expression in the resulting tumours.

Results: Elevated AOX1 protein levels have been observed in gallbladder carcinoma tissues, with such upregulation linked to a negative prognostic outlook for patients. In vitro analyses demonstrate that enhanced AOX1 expression facilitates gallbladder carcinoma cell proliferation, migration, and invasion, while AOX1 suppression yields an inhibitory effect on these cellular behaviors. Western blot results reveal an inverse relationship between AOX1 and E-cadherin levels, yet was positively correlation with N-Cadherin, Vimentin, and Snail within both gallbladder Cancer cells and in vivo xenograft tumours. Further mechanistic investigation indicates that AOX1 elevation augments Reactive Oxygen Species (ROS) production and initiates the Wnt/β-catenin signaling pathway in these cells. The application of N-acetylcysteine (NAC) and/or KY1797K attenuates the proliferative, migratory, and invasive enhancements imparted by AOX1 overexpression and reinforces these effects when AOX1 is silenced-achieved through ROS mitigation and the obstruction of the Wnt/β-catenin pathway. In vivo studies corroborate these findings, showing AOX1 overexpression to amplify xenograft tumor growth and mesenchymal marker expression, whereas AOX1 interference did the opposite.

Conclusions: The study indicates that AOX1 functions as a carcinogenic factor in gallbladder carcinoma, enhancing cell proliferation, migration, invasion, and the EMT. These effects are driven by the activation of the Wnt/β-catenin pathway mediated by Reactive Oxygen Species (ROS). Therefore,AOX1 presents potential as a valuable prognostic and diagnostic marker as well as a target for therapeutic intervention in the gallbladder Cancer.

AOX1; EMT; Gallbladder cancer; ROS; β-Catenin.