wedelolactone and Liver-Neoplasms

Polycomb repressive complex 2 (PRC2), which is responsible for the trimethylation of H3K27 (H3K27me3), plays a part in tumorigenesis, development and/or maintenance of adult tissue specificity. The pivotal role of PRC2 in cancer makes it a therapeutic target for epigenetic cancer therapy. However, natural compounds targeting the enhancer of zeste homolog 2 (EZH2) - embryonic ectoderm development (EED) interaction to disable PRC2 complex are scarcely reported. Here, we reported the screening and identification of natural compounds which could disrupt the EZH2-EED interaction. One of these compounds, wedelolactone, binds to EED with a high affinity (KD = 2.82 μM), blocks the EZH2-EED interaction in vitro, induces the degradation of PRC2 core components and modulates the expression of detected PRC2 downstream targets and cancer-related genes. Furthermore, some PRC2-dependent cancer cells undergone growth arrest upon treatment with wedelolactone. Thus, wedelolactone and its derivatives which target the EZH2-EED interaction could be candidates for the treatment of PRC2-dependent cancer.

Topics: Apoptosis; Cell Movement; Cell Proliferation; Coumarins; Enhancer of Zeste Homolog 2 Protein; HEK293 Cells; Hep G2 Cells; Humans; K562 Cells; Liver Neoplasms; Polycomb Repressive Complex 2

Peroxisome proliferator activated receptor-alpha (PPARα) plays a major role in the regulation of lipid and glucose homeostasis, and inflammatory responses. The objectives of the study were to systematically investigate the effects of TNF-α and its regulatory pathway on PPARα expression in HepG2 cells using Real-Time RT-PCR and western blot analysis. Here, TNF-α suppressed PPARα mRNA expression in a dose- and time-dependent manner at the level of gene transcription. Pre-treatment of cells with 10μM of Wedelolactone for 2h was sufficient to restore PPARα expression to basal levels and also affected the expression of PPARα-regulated genes. This study also demonstrated that TNF-α represses PPARα expression by augmenting the activity of canonical NF-κB signalling pathway. This was shown by the abrogation of TNF-α-mediated PPARα down-regulation, after both p65 and p50 were knocked down via siRNA. The IKK contributes to IκBα degradation and mediates inducible phosphorylation of p105 at Ser933. Surprisingly, phosphorylation of p65 at Ser468 and Ser536 were severely abrogated with Wedelolactone inhibition, suggesting that Ser468 and Ser536, but not Ser276, may mediate the TNF-α inhibitory action on PPARα gene expression. These results suggest that TNF-α might, at least in part, suppress PPARα expression through activation of IKK/p50/p105/p65 pathway. Furthermore, phosphorylation of p65 at Ser468 and Ser536 may play a crucial role in the mechanism that limits PPARα production in the human HepG2 cells.

Topics: Carcinoma, Hepatocellular; Cell Line, Tumor; Coumarins; Down-Regulation; Hep G2 Cells; Humans; I-kappa B Kinase; Liver Neoplasms; NF-kappa B; NF-kappa B p50 Subunit; Phosphorylation; PPAR alpha; RNA Interference; RNA, Messenger; RNA, Small Interfering; Signal Transduction; Transcription Factor RelA; Tumor Necrosis Factor-alpha

Eclipta prostrata L., (Asteraceae), is used in China for both food and medicine purposes. This research is concerned with the isolation and purification of phytochemical constituents from the aerial parts of E. prostrata, using gradient solvent fractionation, macroporous resin, silica gel, Sephadex LH-20 and ODS columns, and TLC analyses. Four fractions (water, 30% ethanol, 60% ethanol and 90% ethanol) were obtained. Four compounds, wedelolactone (I), eclalbasaponin I (II), luteolin (III) and luteolin-7-O-glucoside (IV) were purified and their structures were identified by the interpretation of spectroscopic analyses including MS, (1)H and (13)C NMR. Antitumor activities of extracts (total fraction), four fractions and the isolated compounds were assessed using hepatoma cell smmc-7721 as an in vitro assay system. The 30% ethanol fraction and eclalbasaponin I dose-dependently inhibited the proliferation of hepatoma cell smmc-7721 with IC(50) values of 74.2399 and 111.1703 μg/ml, respectively, more strongly compared with 5-fluorouracil positive control group with the IC(50) value of 195.3131 μg/ml. Antitumor activities of other fractions and compounds were lower than positive control. These results suggested that some specific compounds or extracts from E. prostrata are potential sources of natural anti-tumor materials and worthy of further study.

Topics: Animals; Antineoplastic Agents, Phytogenic; Carcinoma, Hepatocellular; Cell Line, Tumor; China; Coumarins; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Eclipta; Flavones; Glucosides; Humans; Liver Neoplasms; Luteolin; Medicine, Chinese Traditional; Molecular Structure; Plant Components, Aerial; Plant Extracts; Plants, Medicinal; Saponins