Abstract
Hepatocellular carcinoma (HCC), the most prevalent liver cancer, is considered one of the most lethal malignancies with a dismal outcome mainly due to frequent intrahepatic and distant metastasis. In the present study, we demonstrated that oroxylin A, a natural product extracted from Scutellaria radix, significantly inhibits transforming growth factor-beta1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) and metastasis in HCC. Oroxylin A blocked the TGF-β1/Smad signaling via upregulating the non-steroidal anti-inflammatory drug-activated gene-1 (NAG-1) expression. Oroxylin A promoted NAG-1 transcription by regulating the acetylation of CCAAT/enhancer binding protein β (C/EBPβ), a transcription factor that binds to the NAG-1 promoter. In terms of the underlying mechanism, oroxylin A may interact with histone deacetylase 1 (HDAC1) by forming hydrogen bonds with GLY149 residue and induce proteasome-mediated degradation of HDAC1 subsequently impairing HDAC1-mediated deacetylation of C/EBPβ and promoting the expression of NAG-1. Taken together, our findings revealed a previously unknown tumor-suppressive mechanism of oroxylin A. Oroxylin A should be further investigated as a potential clinical candidate for inhibiting HCC metastasis.