Disruption of p-AKT/ERβ-Mediated Midkine Signaling Promotes the Antimetastatic Effects of Timosaponin AIII in Nasopharyngeal Carcinoma Cells

Background: Nasopharyngeal carcinoma (NPC) is a highly metastatic epithelial malignancy with limited therapeutic options for advanced disease. Timosaponin AIII (TSAIII), a natural steroidal saponin, exhibits antitumor activity; however, its effects on NPC progression and the molecular mechanisms remain unclear. Method: Cell viability, proliferation, apoptosis, migration, and invasion were evaluated using cell growth, colony formation, Annexin V/PI, and Transwell assays. Human chemokine array and The Cancer Genome Atlas (TCGA) analyses identified midkine (MDK) as a potential molecular target of TSAIII and its clinical relevance in NPC. Western blotting, qRT-PCR, immunofluorescence, and chromatin immunoprecipitation (ChIP) assays were used to investigate the underlying signaling mechanisms. Antimetastatic activity was further evaluated in C.B17-SCID mice. Results: TSAIII suppressed NPC cell migration and invasion with minimal cytotoxicity, accompanied by reduced the expression of p-AKT (Ser473), estrogen receptor β(ERβ) nuclear localization, and MDK expression. Wortmannin enhanced these effects, while TSAIII attenuated latent membrane protein 1 (LMP1)-induced signaling. In vivo, TSAIII significantly reduced lung metastasis without apparent toxicity. Conclusions: TSAIII suppresses NPC metastasis by targeting the LMP1/p-AKT/ERβ/MDK signaling axis, supporting its potential as an antimetastatic therapeutic candidate for NPC.