β‑carotene reverses tobacco smoke‑induced gastric EMT via Notch pathway in vivo.

Tobacco smoke is one of the serious risk factors of gastric cancer. Epithelial‑mesenchymal transition (EMT) has been shown to be associated with the initiation and carcinogenesis of gastric cancer. The role of Notch pathway in regulating tobacco smoke-induced EMT has not been investigated. β‑carotene, a carotenoid present in fruits, vegetables and rice, suppresses cancer progression. In this investigation, we evaluated the regulatory role of Notch pathway in tobacco smoke‑mediated gastric EMT and the preventive effect of β‑carotene using a BALB/c mouse smoking model. Exposure of mice to tobacco smoke reduced levels of epithelial markers, while the expression of mesenchymal markers were increased. We further found that Notch pathway modulated tobacco smoke-triggered EMT in the stomach of mice, as evidenced by these findings that tobacco smoke activated Notch activities, and tobacco smoke induced EMT was reversed by blocking Notch activities with FLI‑06. Moreover, treatment of β‑carotene prevented tobacco smoke‑mediated activation of Notch and EMT changes. Our data suggested that Notch regulate tobacco smoke induced gastric EMT and the protective effects of β‑carotene in vivo. These findings may establish a new mechanism for tobacco smoke-associated gastric tumorigenesis and its chemoprevention.