cyclin-d1 and flavone

Hepatocellular carcinoma (HCC), a highly aggressive form of solid tumor, has been increasing in South East Asia. The lack of effective therapy necessitates the introduction of novel chemopreventive strategies to counter the substantial morbidity and mortality associated with the disease. Recently, we reported that dimethoxy flavone (DMF), a methylated flavone derived from chrysin, significantly suppressed the development of preneoplastic lesions induced by N-nitrosodiethylamine (DEN) in rats, although the mechanism of action was not known. In the present study, we have investigated the effects of DMF administration on gene expression changes related to the inflammation-mediated NF-kB pathway, Wnt pathway and apoptotic mediators in DEN-induced preneoplastic nodules. There was a significant increase in inflammatory markers like cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) and a decrease in apoptotic mediators like p53, caspase-3 and bax in DEN-treated rats when compared to the control group. Activation of NF-kB was noticed by an elevated expression of nuclear protein expression of NF-kB and cytoplasmic phospho-IkBαSer(32/36) in the same animals. Likewise, upregulation of canonical Wnt pathway was noticed by elevated expression of nuclear protein levels of phospho-β-cateninThr(393) and cytoplasmic casein kinase-2 (CK2), Dvl2 and cyclin D1 levels, along with a simultaneous decrease in expression of phospho-GSK3β(Ser9). Dietary DMF (100mg/kg) administration inhibited liver nodule incidence and multiplicity by 82% and 78%, respectively. DMF also reversed the activation of NF-kB and Wnt pathway as shown by the decrease in protein expression of several proteins. Results of the present investigation provide evidence that attenuation of Wnt pathway and suppression of inflammatory response mediated by NF-kB could be implicated, in part, in the chemopreventive effects of methylated flavone. Therefore, the present findings hold great promise for the utilization of DMF as an effective chemotherapeutic agent in treating early stages of liver cancer.

Topics: Animals; Antineoplastic Agents; Apoptosis; bcl-2-Associated X Protein; Carcinoma, Hepatocellular; Casein Kinase II; Caspase 3; Cyclin D1; Cyclooxygenase 2; Diethylnitrosamine; Disease Models, Animal; Flavones; Flavonoids; Gene Expression Regulation, Neoplastic; Liver Neoplasms; Male; NF-kappa B; Nitric Oxide Synthase Type II; Precancerous Conditions; Rats; Rats, Wistar; Signal Transduction; Tumor Suppressor Protein p53; Up-Regulation; Wnt Proteins

Extracts of Artemisia asiatica Nakai (Asteraceae) possess anti-inflammatory and anti-oxidative activities. Eupatilin (5,7-dihydroxy-3',4',6-trimethoxyflavone), one of the pharmacologically active ingredients derived from A. asiatica, was shown to induce apoptosis in human promyelocytic leukemia (HL-60) cells [Mutat Res 496 (2001) 191]. In the present study, we examined the cytostatic effects of eupatilin in H-ras-transformed human breast epithelial (MCF10A-ras) cells. Eupatilin inhibited the growth of MCF10A-ras cells in a concentration-dependent and time-related manner. To explore whether the anti-proliferative effects of eupatilin could be mediated through modulation of the cell cycle in MCF10A-ras, DNA contents were analyzed by the flow cytometry. Eupatilin inhibited the expression of cyclin D1, cyclin B1, Cdk2 and Cdc2 that are key regulators of the cell cycle. In addition, eupatilin treatment led to elevated expression of p53 and p27Kip1 that act as Cdk inhibitors. It has been known that the Ras-signaling pathway plays integral roles in the induction of cyclin D1. Eupatilin inhibited the activation of ERK1/2 as well as expression of Raf-1 and Ras in MCF10A-ras cells. Thus, the inhibitory effect of eupatilin on cyclin D1 expression appears to be mediated by targeting the Raf/MEK/ERK signaling cascades. Eupatilin did not change activation of Akt, an important component of cell-survival pathways. In conclusion, the anti-proliferative effect of eupatilin in MCF10A-ras cells is associated with its blockade of cell cycle progression which appears to be attributable in part to inhibition of ERK1/2 activation.

Topics: Artemisia; Cell Cycle; Cell Cycle Proteins; Cell Division; Cell Survival; Cell Transformation, Neoplastic; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p27; Cyclin-Dependent Kinases; Epithelial Cells; Flavones; Flavonoids; G1 Phase; Genes, ras; HL-60 Cells; Humans; Mammary Glands, Human; Mitogen-Activated Protein Kinases; Mitosis; Proto-Oncogene Proteins c-raf; S Phase; Signal Transduction; Tumor Suppressor Protein p53; Tumor Suppressor Proteins; Up-Regulation