6-Shogaol induces apoptosis in human hepatocellular carcinoma cells and exhibits anti-tumor activity in vivo through endoplasmic reticulum stress.
Ontology highlight
ABSTRACT: 6-Shogaol is an active compound isolated from Ginger (Zingiber officinale Rosc). In this work, we demonstrated that 6-shogaol induces apoptosis in human hepatocellular carcinoma cells in relation to caspase activation and endoplasmic reticulum (ER) stress signaling. Proteomic analysis revealed that ER stress was accompanied by 6-shogaol-induced apoptosis in hepatocellular carcinoma cells. 6-shogaol affected the ER stress signaling by regulating unfolded protein response (UPR) sensor PERK and its downstream target eIF2?. However, the effect on the other two UPR sensors IRE1 and ATF6 was not obvious. In prolonged ER stress, 6-shogaol inhibited the phosphorylation of eIF2? and triggered apoptosis in SMMC-7721 cells. Salubrinal, an activator of the PERK/eIF2? pathway, strikingly enhanced the phosphorylation of eIF2? in SMMC-7721 cells with no toxicity. However, combined treatment with 6-shogaol and salubrinal resulted in significantly increase of apoptosis and dephosphorylation of eIF2?. Overexpression of eIF2? prevented 6-shogaol-mediated apoptosis in SMMC-7721 cells, whereas inhibition of eIF2? by small interfering RNA markedly enhanced 6-shogaol-mediated cell death. Furthermore, 6-shogaol-mediated inhibition of tumor growth of mouse SMMC-7721 xenograft was associated with induction of apoptosis, activation of caspase-3, and inactivation of eIF2?. Altogether our results indicate that the PERK/eIF2? pathway plays an important role in 6-shogaol-mediated ER stress and apoptosis in SMMC-7721 cells in vitro and in vivo.
SUBMITTER: Hu R
PROVIDER: S-EPMC3387266 | biostudies-literature | 2012
REPOSITORIES: biostudies-literature
ACCESS DATA