title: Emodin regulates apoptotic pathway in human liver cancer cells.
abstract: Emodin, a natural anthraquinone, has been reported to possess antiproliferative effects in many cancer cell lines. However, anticancer mechanism against human liver cancer remains unclear. In this study, we observed that emodin induced apoptosis in HepG2 cells and caused a significant accumulation of cells in the G1 phase. Western blot data showed that emodin treatment caused the increasing of release of cytochrome c into cytosol from mitochondria and the activation of caspase-8 and caspase-9, which suggest that the intrinsic and extrinsic pathways could be involved. Emodin treatment also resulted in a dose-dependent accumulation of intracellular reactive oxygen species. Furthermore, emodin increased the protein level of p53 and decreased the protein level of NF-κB/p65 in HepG2 cells, which indicated these two regulators might play a role in emodin-induced apoptosis. Computational modeling showed that emodin could directly bind to the BH3 domain of Bcl-2 through forming one hydrogen bond with Ala146 residue in Bcl-2. From these examinations, emodin not only significantly downregulated expression of Bcl-2 but also inhibited the heterodimerization of Bcl-2 with Bax because of strong interaction between emodin and Bcl-2. These suggest that emodin induces apoptosis in liver cancer cell line through a multifaceted complex cascade of events.
authors.affiliation: Key Laboratory of Combinatorial Biosynthesis and Drug Discovery (Wuhan University), Ministry of Education and Wuhan University School of Pharmaceutical Sciences, Wuhan 430071, China. jq_yu@126.com
authors.forename: Jian-Qing
authors.initials: JQ
authors.lastname: Yu
authors.forename: Wei
authors.initials: W
authors.lastname: Bao
authors.forename: Jia-Chuan
authors.initials: JC
authors.lastname: Lei
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D004642:Emodin / Q000494:pharmacology*; D056945:Hep G2 Cells / Q000187:drug effects*; D006801:Humans; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D051996:Transcription Factor RelA / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D019253:Proto-Oncogene Proteins c-bcl-2; C498143:RELA protein, human; D017382:Reactive Oxygen Species; C495901:TP53 protein, human; D051996:Transcription Factor RelA; D016159:Tumor Suppressor Protein p53; D045304:Cytochromes c; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D004642:Emodin