Apoptotic effects of over-expressed estrogen receptor-beta on LoVo colon cancer cell is mediated by p53 signalings in a ligand-dependent manner

Epidemiologic studies reported that the prevalence of hereditary non-polyposis colon cancer (HNPCC) in male is about 1.5-fold higher than that in female. Decreases in circulatory estradiol (E2) have been reported to downregulate the expression of E2 receptor (ER) and significantly increase the risk of colorectal cancer. Patients that received E2 replacement therapy were found to have a reduction in the incidence of colon adenoma and carcinoma. Furthermore, significant decreases in the expression of ER have been found in colorectal cancer specimens. These data strongly suggest the protective roles of E2 and ER against colorectal cancer. However, the mechanisms remain unexplored. LoVo cells were transient transfected to overexpress ER-beta, DNA fragmentation and caspase activity assay were performed to evaluate apoptotic effects. Western blotting was used to evaluate protein levels, and luciferase activity assay to measure the TNF-alpha promoter activity. Our data clearly demonstrated that E2 and ER-beta alone could upregulate p21 and p27 proteins, which further activate caspase-8 and caspase-9 to induce apoptosis in LoVo cell, and the ER-beta. effects were enhanced by E2. However, overexpressed ER-beta did not influence the expression and promoter activity of TNF-alpha. In addition, E2 and overexpressed ER-beta downregulated the beta-catenin proteins which cause the downregulation of its target genes, cyclin D1 and Rb, to inhibit the cell cycle and cell proliferation. The results indicate that overexpressed ER-beta may induce LoVo cell apoptosis and anti-proliferation by increasing p53 signaling in a ligand-dependent manner, and without hTNF-alpha involvement. Efforts aiming at enhancing ER-beta expression and/or activity may prove to be an attractive alternative therapy against colorectal cancer.     

A novel heterozygous deletion in the EVC2 gene causes Weyers acrofacial dysostosis

Weyers acrofacial dysostosis (MIM 193530) is an autosomal dominant disorder clinically characterized by mild short stature, postaxial polydactyly, nail dystrophy and dysplastic teeth. Ellis–van Creveld syndrome (EvC, MIM 225500) is an autosomal recessive disorder with a similar, but more severe phenotype. Mutations in the EVC have been identified in both syndromes. However, the EVC mutations only occur in a small proportion of EvC patients. Recently, mutations in a new gene, EVC2, were found to be associated with other EvC cases. The EVC and EVC2 are located close to each other in a head-to-head configuration and may be functionally related. In this study, we report identification of a novel heterozygous deletion in the EVC2 that is responsible for autosomal dominant Weyers acrofacial dysostosis in a large Chinese family. This constitutes the first report of Weyers acrofacial dysostosis caused by this gene. Hence, the spectrum of malformation syndromes due to EVC2 mutations is further extended. Our data provides conclusive evidence that Weyers acrofacial dysostosis and EvC syndrome are allelic and genetically heterogeneous conditions. X. Ye and G. Song contributed equally to this work     

Antiplatelet prenylflavonoids from Artocarpus communis

Four flavonoids, dihydroartomunoxanthone (1), artomunoisoxanthone (2), cyclocomunomethonol (3) and artomunoflavanone (4), together with three known compounds, artochamins B (5), D and artocommunol CC (6) were isolated from the cortex of the roots of Artocarpus communis. The structures of 1-4 were determined by spectroscopic methods. The antiplatelet effects of the flavonoids, 1-3, 5 and 6 on human platelet-rich plasma (PRP) were evaluated. Of the compounds tested in human PRP, compounds 1, 5 and 6 showed significant inhibition of secondary aggregation induced by adrenaline. It is concluded that the antiplatelet effect of 1, 5 and 6 is mainly owing to an inhibitory effect on thromboxane formation.     

Contributions of PIP(2)-specific-phospholipase C and free salicylic acid to heat acclimation-induced thermotolerance in pea leaves

The relationship between the accumulation in endogenous free salicylic acid (SA) induced by heat acclimation (37 degrees C) and the activity of PIP(2)-phospholipase C (PIP(2)-PLC; EC 3.1.4.3) in the plasma membrane fraction was investigated in pea (Pisum sativum L.) leaves. We focused our attention on the hypothesis that positive SA signals induced by heat acclimation may be relayed by PIP(2)-PLC. Heat acclimation induced an abrupt elevation of free SA preceding the activation of PLC toward PIP(2). Immunoblotting indicated a molecular mass with 66.5kDa PLC plays key role in the development of thermotolerance in pea leaves. In addition, some characterizations of PLC toward PIP(2) isolated from pea leaves with two-phase purification containing calcium concentration, pH and a protein concentration were also studied. Neomycin sulfate, a well-known PIP(2)-PLC inhibitor, was employed to access the involvement of PIP(2)-PLC in the acquisition of heat acclimation induced-thermotolerance. We were able to identify a PIP(2)-PLC, which was similar to a conventional PIP(2)-PLC in higher plants, from pea leaves suggesting that PIP(2)-PLC was involved in the signal pathway that leads to the acquisition of heat acclimation induced-thermotolerance. On the basis of these results, we conclude that the involvement of free SA may function as the upstream event in the stimulation of PIP(2)-PLC in response to heat acclimation treatment.     

QTL mapping of grain length in rice (Oryza sativa L.) using chromosome segment substitution lines

Chromosome segment substitution (CSS) lines have the potential for use in QTL fine mapping and map-based cloning. The standard t-test used in the idealized case that each CSS line has a single segment from the donor parent is not suitable for non-idealized CSS lines carrying several substituted segments from the donor parent. In this study, we present a likelihood ratio test based on stepwise regression (RSTEP-LRT) that can be used for QTL mapping in a population consisting of non-idealized CSS lines. Stepwise regression is used to select the most important segments for the trait of interest, and the likelihood ratio test is used to calculate the LOD score of each chromosome segment. This method is statistically equivalent to the standard t-test with idealized CSS lines. To further improve the power of QTL mapping, a method is proposed to decrease multicollinearity among markers (or chromosome segments). QTL mapping with an example CSS population in rice consisting of 65 non-idealized CSS lines and 82 chromosome segments indicated that a total of 18 segments on eight of the 12 rice chromosomes harboured QTLs affecting grain length under the LOD threshold of 2.5. Three major stable QTLs were detected in all eight environments. Some minor QTLs were not detected in all environments, but they could increase or decrease the grain length constantly. These minor genes are also useful in marker-assisted gene pyramiding.     

Traditional Chinese medicine as dual guardians against hypertension and cancer?

This study utilizes the comprehensive traditional Chinese medicine database TCM Database@Taiwan ( http://tcm.cmu.edu.tw/ ) in conjunction with structure-based and ligand-based drug design to identify multi-function Src inhibitors. The three potential TCM candidates identified as having suitable docking conformations and bioactivity profiles were Angeliferulate, (3R)-2'-hydroxy-3',4'-dimethoxyisoflavan-7-O-beta-D-glucoside (HMID), and 3-[2',6-dihydroxy-5'-(2-propenyl)[1,1'-biphenyl]3-yl]-(E)-2-propenoic acid (3PA). Molecular dynamics simulation demonstrated that the TCM candidates have more stable interactions with the cleft and in complex with Src kinase compared to Saracatinib. Angeliferulate and HMID, both originated from Angelica sinensis, not only interact with Lys298 and amino acids from different loops in the cleft, but also with Asp407 located on the activation loop. These interactions are important to reduce the opening of the activation loop due to phosphorylation, hence stabilize the Src kinase cleft structure and inhibit activation. The TCM candidates also exhibited high affinity to other cancer-related target proteins (EGFR, HER2, and HSP90). Our observations suggest that the TCM candidates might have multi-targeting effects in hypertension and cancer.     

3',4'-didemethylnobiletin induces phase II detoxification gene expression and modulates PI3K/Akt signaling in PC12 cells

Oxidative stress is considered a major cause of neurodegenerative disorders. In this work, we investigated the cytoprotective effects and mechanisms of the citrus flavonoid nobiletin (NOB) and its metabolite, 3',4'-didemethylnobiletin (3',4'-dihydroxy-5,6,7,8-tetramethoxyflavone; DTF), in PC12 cells. Both NOB and DTF exhibited strong potency in attenuating serum withdrawal- and H(2)O(2)-caused cell death and increased intracellular GSH level via upregulation of both catalytic and modifier subunits of glutamate-cysteine ligase (GCL). However, only DTF suppressed intracellular ROS accumulation in H(2)O(2)-treated cells, induced heme oxygenase-1 (HO-1) expression, and enhanced nuclear factor E2-related factor 2 (Nrf2) binding to the ARE. Nevertheless, DTF-mediated HO-1 upregulation was independent of Nrf2 activation because knockdown of Nrf2 expression by siRNA did not affect its expression. DTF suppressed NF-κB activation, and addition of NF-κB inhibitor, pyrrolidine dithiocarbamate or Bay 11-7082, synergistically enhanced DTF-mediated HO-1 expression, indicating that HO-1 induction is associated with NF-κB suppression. NOB and DTF also activated the ERK, JNK, and Akt pathways in PC12 cells that had undergone serum starvation. Addition of pharmacological kinase inhibitors, U0126, SP600125, and LY294002, caused cytotoxicity and the last significantly attenuated NOB- and DTF-mediated antiapoptotic actions, indicating the involvement of PI3K/Akt signaling in their cytoprotective effects. In conclusion, HO-1 and GCL upregulation and intrinsic ROS-scavenging activity may contribute to DTF-mediated cytoprotection. Furthermore, modulation of PI3K/Akt signaling is involved in channeling the DTF stimulus for cell survival against oxidative insults.