title: Purified vitexin compound 1 induces apoptosis through activation of FOXO3a in hepatocellular carcinoma.
abstract: We previously reported that purified vitexin compound 1 (VB1, a neolignan from the seed of Chinese herb Vitex negundo) exhibited antitumor activity in cancer cell lines and xenograft models. In the present study, we examined the molecular mechanisms by which activation of the FOXO3a transcription factor mediated VB1-induced apoptosis in hepatocellular carcinoma (HCC) cells. The effects of VB1 on the proliferation of HCC cell lines HepG2, Hep3B, Huh-7 and human embryo liver L-02 cells were investigated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptotic death in HepG2 cells was examined using an enzyme-linked immunosorbent assay (ELISA) detection kit, flow cytometry after propidium iodide (PI) staining, and by DNA agarose gel electrophoresis. Caspase activity was measured using ELISA. The AKT/FOXO3a and ERK/FOXO3a pathways were analyzed using western blotting. VB1 inhibited human HCC cell proliferation in a concentration-dependent manner and increased the percentage of sub-G1 population HepG2 cells. Histone/DNA fragmentation and active caspase-3, -8 and -9 levels increased in a concentration-dependent manner and a DNA ladder was formed. The phosphorylation of AKT and ERK1/2 were inhibited and FOXO3a transcription factor was activated, resulting in apoptotic death. Knockdown of AKT1 by small interfering RNA (siRNA) and the MEK1/2 inhibitor, PD98059, enhanced VB1-induced apoptosis and FOXO3a transcriptional activity. Suppression of FOXO3a expression by siRNA inhibited VB1-induced apoptosis. VB1 induced expression of Bim, TRAIL, DR4 and DR5. Activation of the FOXO3a transcription factor appears to mediate pro-apoptotic effects of VB1 by inhibiting the AKT and ERK pathways.
authors.affiliation: Department of Cardiology, The Third Xiangya Hospital of Central South University, Changsha, Hunan 410013, P.R. China.
authors.forename: Jian-Gang
authors.initials: JG
authors.lastname: Wang
authors.forename: Xing-Xing
authors.initials: XX
authors.lastname: Zheng
authors.forename: Guang-Yao
authors.initials: GY
authors.lastname: Zeng
authors.forename: Ying-Jun
authors.initials: YJ
authors.lastname: Zhou
authors.forename: Hong
authors.initials: H
authors.lastname: Yuan
mesh_terms: D047310:Apigenin / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D051017:Apoptosis Regulatory Proteins / Q000096:biosynthesis; D000072224:Bcl-2-Like Protein 11; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D053148:Caspase 3 / Q000096:biosynthesis; D053181:Caspase 8 / Q000096:biosynthesis; D053453:Caspase 9 / Q000096:biosynthesis; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D053938:DNA Fragmentation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D056945:Hep G2 Cells; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000235:genetics; D008565:Membrane Proteins / Q000096:biosynthesis; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand / Q000096:biosynthesis; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000096:biosynthesis; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D051017:Apoptosis Regulatory Proteins; C000606775:BCL2L11 protein, human; D000072224:Bcl-2-Like Protein 11; C499517:FOXO3 protein, human; D005419:Flavonoids; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D008565:Membrane Proteins; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D053220:Receptors, TNF-Related Apoptosis-Inducing Ligand; D053221:TNF-Related Apoptosis-Inducing Ligand; C105190:TNFRSF10A protein, human; C505653:TNFSF10 protein, human; D047310:Apigenin; C032731:vitexin; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one