Saikosaponin D Is Associated with Anti-Tumor Effects and Markers of Autophagy and Endoplasmic Reticulum Stress in Human Endometrial Cancer Ishikawa Cells

Background/Objectives: Saikosaponin D (SSD) is a bioactive compound from traditional Chinese herbs with known anti-tumor activities, including apoptosis induction, autophagy modulation, and inhibition of cell migration and invasion. However, the mechanisms underlying its effects on human endometrial cancer Ishikawa cells remain elusive. This study aimed to investigate the anti-tumor effects of SSD on EC Ishikawa cells and elucidate the molecular pathways involved, focusing on DNA damage, cell cycle regulation, autophagy, endoplasmic reticulum (ER) stress, and AMPK signaling. Methods: We performed in vitro experiments using Ishikawa cells and in vivo studies using a female BALB/c nude mouse xenograft model. DNA damage was assessed via comet assay, intracellular Ca2+ concentration via Fluo-3 AM staining, autophagy via transmission electron microscopy, and apoptosis via flow cytometry. Autophagy was inhibited using 3-methyladenine, and ER stress was modulated with the PERK inhibitor GSK2656157. Protein expression levels of related genes were analyzed by western blotting. No preregistration number or CONSORT details applied, as this was a pre-clinical study. Results: SSD treatment was associated with DNA damage and G2/M phase cell cycle arrest in Ishikawa cells both in vitro and in vivo. SSD was associated with an increased LC3II/LC3I ratio and activation of the AMPK pathway. It was also associated with ER stress, as evidenced by downregulation of PERK, mTOR, and eIF2α, and upregulation of p-eIF2α. Furthermore, SSD was associated with modulation of the AMPK signaling pathway to inhibit cell migration and invasion. Conclusions: SSD exerts anti-tumor effects on human EC Ishikawa cells in vitro and in vivo through mechanisms involving DNA damage, G2/M arrest, autophagy, ER stress, and AMPK-mediated inhibition of migration and invasion. These findings suggest that SSD may represent a potential therapeutic agent for EC.