Trifolirhizin targets PTK6 to induce autophagy and exerts antitumor effects in nasopharyngeal carcinoma

Trifolirhizin, a natural flavonoid glycoside, has been proved to exert antitumor activities in various human malignant tumors. PTK6 was identified as a direct target of trifolirhizin based on public database SuperPred (https://prediction.charite.de/). Overexpressed PTK6 in a variety of tumors is closely associated with the malignant development of tumors. Herein, this present research was formulated to elaborate the effects of trifolirhizin on the biological behaviors of nasopharyngeal carcinoma (NPC) cells and to probe into the intrinsic mechanisms. The current study firstly elucidated the tumor-inhibiting functions of trifolirhizin in NPC malignant progression from the perspective of targeting inhibition of PTK6. In this work, CCK-8 for cell viability, EdU staining for cell proliferation, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining for cell apoptosis and immunofluorescence staining for LC3 expression were performed. Besides, levels of proliferation-related, apoptosis-related and autophagy-related proteins were detected by western blot analysis. Moreover, molecular docking of trifolirhizin with PTK6 was conducted to seek the compound-protein binding potential. It was demonstrated that trifolirhizin treatment inhibited the proliferation and promoted the apoptosis of NPC cells as well as strengthened autophagy in NPC cells. Furthermore, it was verified that trifolirhizin targeted PTK6 and negatively regulated PTK6 expression. The suppressive effects of trifolirhizin on the malignant behaviors of NPC cells and the enhancing effect of trifolirhizin on autophagy in NPC cells were partly abolished upon upregulation of PTK6. To conclude, findings suggested that trifolirhizin may downregulate PTK6 expression to induce autophagy and exert the antitumor activities in NPC.