IL‑6/STAT3 signaling pathway‑mediated apoptosis induced by medical ozone water in liver cancer: A mechanistic study

Liver cancer is one of the most common and aggressive malignancies worldwide, with high rates of proliferation, migration and invasion contributing to poor patient outcomes. Ozonated water has potential anti‑tumor effects. However, the underlying mechanisms, particularly its interaction with key signaling pathways such as IL‑6/STAT3, remain poorly understood. The IL‑6/STAT3 pathway serves a critical role in cancer progression, regulating processes such as cell survival and metastasis. To the best of our knowledge, however, the association between ozonated water and this pathway in liver cancer cells has not been thoroughly investigated. Therefore, the objective of the present study was to explore the effects of ozonated water on the proliferation, migration and invasion of HepG2 and Huh‑7 liver cancer cells and determine the relationship between ozone and the IL‑6/STAT3 signaling pathway, and the potential mechanism of this pathway in HepG2 cells. Proliferation was evaluated using the Cell Counting Kit‑8 assay. Wound healing assay was used to evaluate migration ability. Transwell assay with Matrigel was used to evaluate invasion ability. Flow cytometry was used for cell apoptosis analysis. Protein expression was estimated by western blot analysis. Treatment with ozone at a concentration of 20 µg for 24 h inhibited liver cancer cell proliferation, migration and invasion capacities. Flow cytometric analysis revealed a marked increase in apoptosis rate in ozone‑treated HepG2 cells (25.15±0.72 vs. 12.90±0.83% in control treated with MEM). Western blotting indicated downregulation of IL‑6/STAT3 pathway components in ozone‑treated HepG2 cells, with IL‑6 and phosphorylated (p‑)STAT3 expression levels showing the most pronounced reduction. Concurrently, Bcl‑2 protein expression significantly decreased in the ozone‑treated cells, whereas cleaved caspase‑3 exhibited upregulated expression in treated cells. Ozone inhibited the proliferation, migration and invasion of and induced the apoptosis of liver cancer cells. Medical ozone water may induce liver cancer cell apoptosis by downregulating the IL‑6/STAT3 signaling pathway, as evidenced by decreased expression of p‑STAT3 and downstream anti‑apoptotic proteins (Bcl‑2) alongside apoptotic induction.