Hispidulin induces ER stress-mediated apoptosis in human hepatocellular carcinoma cells in vitro and in vivo by activating AMPK signaling pathway

• Published in: Acta pharmacologica Sinica 2019-05, Vol.40 (5), p.666-676
• Main Authors: Han, Mei, Gao, Hui, Xie, Jing, Yuan, Yin-Ping, Yuan, Quan, Gao, Ming-Quan, Liu, Kai-Li, Chen, Xue-Hong, Han, Yan-Tao, Han, Zhi-Wu
• Format: Article
• Language: English
• Subjects: AMP-Activated Protein Kinases - metabolism; Animals; Antineoplastic Agents - pharmacology; Antineoplastic Agents - therapeutic use; Antitumor agents; Apoptosis; Apoptosis - drug effects; Carcinoma, Hepatocellular - drug therapy; Carcinoma, Hepatocellular - pathology; Cell Line, Tumor; Endoplasmic reticulum; Endoplasmic Reticulum Stress - drug effects; Flavones - pharmacology; Flavones - therapeutic use; Hepatocellular carcinoma; Humans; Liver cancer; Liver Neoplasms - drug therapy; Liver Neoplasms - pathology; Male; Medicinal plants; Mice, Inbred BALB C; Mice, Nude; Mitochondria; Phenolic compounds; Phenols; Protein folding; Signal transduction; Signal Transduction - drug effects; siRNA; TOR protein; Unfolded Protein Response - drug effects; Xenograft Model Antitumor Assays; Xenografts
• ISSN: 1671-4083; 1745-7254
• DOI: 10.1038/s41401-018-0159-7

Hispidulin (4',5,7-trihydroxy-6-methoxyflavone) is a phenolic flavonoid isolated from the medicinal plant S. involucrata, which exhibits anti-neoplastic activity against several types of cancer. However, the mechanism underlying its anti-cancer activity against hepatocellular carcinoma (HCC) has not been fully elucidated. In this study, we investigated whether and how hispidulin-induced apoptosis of human HCC cells in vitro and in vivo. We showed that hispidulin (10, 20 μmol/L) dose-dependently inhibited cell growth and promoted apoptosis through mitochondrial apoptosis pathway in human HCC SMMC7721 cells and Huh7 cells. More importantly, we revealed that its pro-apoptotic effects depended on endoplasmic reticulum stress (ERS) and unfolded protein response (UPR), as pretreatment with salubrinal, a selective ERS inhibitor, or shRNA targeting a UPR protein CHOP effectively abrogated hispidulin-induced cell apoptosis. Furthermore, we showed that hispidulin-induced apoptosis was mediated by activation of AMPK/mTOR signaling pathway as pretreatment with Compound C, an AMPK inhibitor, or AMPK-targeting siRNA reversed the pro-apoptotic effect of hispidulin. In HCC xenograft nude mice, administration of hispidulin (25, 50 mg/kg every day, ip, for 27 days) dose-dependently suppressed the tumor growth, accompanied by inducing ERS and apoptosis in tumor tissue. Taken together, our results demonstrate that hispidulin induces ERS-mediated apoptosis in HCC cells via activating the AMPK/mTOR pathway. This study provides new insights into the anti-tumor activity of hispidulin in HCC.