Cryptotanshinone inhibits esophageal squamous-cell carcinoma in vitro and in vivo through the suppression of STAT3 activation

Purpose: Esophageal squamous-cell carcinoma (ESCC) is the most common subtype of esophageal cancer, with a poor clinical outcome. Cryptotanshinone (CTS) is the main bioactive compound from the root of Salvia miltiorrhiza Bunge. Our study aimed to investigate the anti-cancer effects and molecular mechanisms of CTS on ESCC. Materials and methods: We investigated the anti-tumor activity of CTS on ESCC in vitro and in vivo. Activation of the STAT3 signaling pathway was evaluated in ESCC and HEK-Blue™ IL-6 cells. Cell viability was assessed by the MTT assay. Apoptosis and cell cycle arrest were assessed using flow cytometry. Cell migration was detected by a scratch wound assay. Results: CTS inhibited STAT3 expression and IL-6-mediated STAT3 activation in esophageal cancer cells. Subsequently, CTS dose-dependently inhibited the proliferation of esophageal cancer cells via induction of cell apoptosis. Furthermore, CTS suppressed the migration of esophageal cancer cells. In vivo, CTS inhibited tumor growth of EC109 cell in xenograft mice without any obvious effect on body weight. Conclusion: Our results indicated that STAT3 inhibition may be a therapeutic target for esophageal cancer. CTS could provide a potential approach for esophageal cancer therapy by influencing the janus kinase-2/STAT3 signaling pathway.