A composition of ursolic acid derivatives from Ludwigia hyssopifolia induces apoptosis in throat cancer cells via the Akt/mTOR and mitochondrial signaling pathways and by modulating endoplasmic reticulum stress

Abstract

Ethnopharmacological relevanceLudwigia hyssopifolia (LH), an ethnopharmacological herb used in Guangxi Zhuang medicine, is known for its extensive therapeutic use in treating throat disorders. The anti–laryngeal-cancer benefits of the ethyl acetate and petroleum ether fractions of the ethanolic extracts of LH have been shown in our prior cell-based research. Nevertheless, the specific impacts and underlying processes by which LH combats throat cancer effects have not been fully understood. Aim of the studyThis study involved the extraction of a composition containing two derivatives of ursolic acid from LH (LH-CUAD). The present study aimed to assess the anti-throat-cancer effects of these derivatives and the underlying mechanisms through in vitro and in vivo experiments. Materials and methodsSolvent extraction, fractionation, chromatography, and semipreparative high-performance liquid chromatography were used for the extraction, purification, and analysis of LH-CUAD. The in vitro and in vivo anti–throat-cancer effects of LH-CUAD were investigated using the throat cancer cell lines Hep-2 and FaDu as well as Hep-2 tumor–bearing nude mice. ResultsLH-CUAD significantly inhibited the proliferation and migration of throat cancer cells without any prominent toxicity. The Hoechst 33258 staining, Annexin V-FITC/PI double-staining assays, and flow cytometry confirmed that LH-CUAD could induce throat cancer cell death from early to late apoptosis in vitro. LH-CUAD exhibited significant antitumor activity and low toxicity in a xenograft model, and induced throat cancer cells apoptosis in vivo. The apoptotic effects of LH-CUAD therapy were validated using Western blotting, which demonstrated the activation of a caspase cascade response triggered by an imbalance between the endoplasmic reticulum and mitochondria. In addition, it was observed that LH-CUAD exhibited inhibitory effects on Akt and mTOR phosphorylation, hence promoting apoptosis. ConclusionsLH-CUAD induces apoptosis in both in vivo and in vitro models of throat cancer. This effect is achieved by activating the mitochondrial pathway, inhibiting the Akt/mTOR pathway and initiating endoplasmic reticulum stress. The findings of this study suggest that LH-CUAD has the potential to offer a novel approach to the clinical management of throat cancer.