Theabrownin Induces Apoptosis and Tumor Inhibition of Hepatocellular Carcinoma Huh7 Cells Through ASK1-JNK-c-Jun Pathway

Purpose: Theabrownin (TB), a main pigment and bioactive component of tea, has been shown anti-tumor activities against carcinomas, but its effects on hepatocellular carcinoma (HCC) remain unclear.

Methods: Hepatocellular carcinoma Huh7 cells were used for analyses. Cell viability assay was performed to determine TB's anti-proliferative effect, and flow cytometry with annexin V-FITC/PI double staining and DAPI staining were performed to determine its pro-apoptotic effect. Real-Time PCR and Western blot assays were conducted to detect the molecular actions of TB. And a xenograft model of zebrafishes was established to evaluate the in vivo effect of TB. SP600125 (JNK Inhibitor) was in vivo and in vitro used to verify the regulatory role of the JNK signaling pathway in the anti-hepatic carcinoma mechanism of TB.

Results: TB exerted significant anti-proliferative and pro-apoptotic effects on Huh7 cells in a dose-dependent manner. The molecular data showed that TB up-regulated the gene expressions of NOXA, PUMA, P21, Bax, and Bim and up-regulated the protein expressions of ASK-1, Bax, phosphorylated JNK, and phosphorylated c-Jun with down-regulation of Bcl-2. The in vivo data showed that TB exerted significant tumor-inhibitory effect which was even stronger than that of cis-platinum. Furthermore, the JNK Inhibitor significantly weakened TB's effects both in vivo and in vitro and blocked the related molecular pathway.

Conclusion: TB exerts anti-proliferative, pro-apoptotic, and tumor-inhibitory effects on Huh7 cells through activation of the JNK signaling pathway. For the first time, this study provides new evidence of anti-HCC effects and mechanism of TB.