In silico discovery of novel Retinoic Acid Receptor agonist structures

BACKGROUND: Several Retinoic Acid Receptors (RAR) agonists have therapeutic activity against a variety of cancer types; however, unacceptable toxicity profiles have hindered the development of drugs. RAR agonists presenting novel structural and chemical features could therefore open new avenues for the discovery of leads against breast, lung and prostate cancer or leukemia. RESULTS: We have analysed the induced fit of the active site residues upon binding of a known ligand. The derived binding site models were used to dock over 150,000 molecules in silico (or virtually) to the structure of the receptor with the Internal Coordinates Mechanics (ICM) program. Thirty ligand candidates were tested in vitro. CONCLUSIONS: Two novel agonists resulting from the predicted receptor model were active at 50 nM. One of them displays novel structural features which may translate into the development of new ligands for cancer therapy

Kaposi's Sarcoma-Associated Herpesvirus K7 Induces Viral G Protein-Coupled Receptor Degradation and Reduces Its Tumorigenicity

The Kaposi's sarcoma-associated herpesvirus (KSHV) genome encodes a G protein-coupled receptor (vGPCR). vGPCR is a ligand-independent, constitutively active signaling molecule that promotes cell growth and proliferation; however, it is not clear how vGPCR is negatively regulated. We report here that the KSHV K7 small membrane protein interacts with vGPCR and induces its degradation, thereby dampening vGPCR signaling. K7 interaction with vGPCR is readily detected in transiently transfected human cells. Mutational analyses reveal that the K7 transmembrane domain is necessary and sufficient for this interaction. Biochemical and confocal microscopy studies indicate that K7 retains vGPCR in the endoplasmic reticulum (ER) and induces vGPCR proteasomeal degradation. Indeed, the knockdown of K7 by shRNA-mediated silencing increases vGPCR protein expression in BCBL-1 cells that are induced for KSHV lytic replication. Interestingly, K7 expression significantly reduces vGPCR tumorigenicity in nude mice. These findings define a viral factor that negatively regulates vGPCR protein expression and reveal a post-translational event that modulates GPCR-dependent transformation and tumorigenicity

Xenobiotic metabolizing enzyme gene polymorphisms predict response to lung volume reduction surgery

<p>Abstract</p> <p>Background</p> <p>In the National Emphysema Treatment Trial (NETT), marked variability in response to lung volume reduction surgery (LVRS) was observed. We sought to identify genetic differences which may explain some of this variability.</p> <p>Methods</p> <p>In 203 subjects from the NETT Genetics Ancillary Study, four outcome measures were used to define response to LVRS at six months: modified BODE index, post-bronchodilator FEV₁, maximum work achieved on a cardiopulmonary exercise test, and University of California, San Diego shortness of breath questionnaire. Sixty-four single nucleotide polymorphisms (SNPs) were genotyped in five genes previously shown to be associated with chronic obstructive pulmonary disease susceptibility, exercise capacity, or emphysema distribution.</p> <p>Results</p> <p>A SNP upstream from glutathione S-transferase pi (<it>GSTP1</it>; p = 0.003) and a coding SNP in microsomal epoxide hydrolase (<it>EPHX1</it>; p = 0.02) were each associated with change in BODE score. These effects appeared to be strongest in patients in the non-upper lobe predominant, low exercise subgroup. A promoter SNP in <it>EPHX1 </it>was associated with change in BODE score (p = 0.008), with the strongest effects in patients with upper lobe predominant emphysema and low exercise capacity. One additional SNP in <it>GSTP1 </it>and three additional SNPs in <it>EPHX1 </it>were associated (p < 0.05) with additional LVRS outcomes. None of these SNP effects were seen in 166 patients randomized to medical therapy.</p> <p>Conclusion</p> <p>Genetic variants in <it>GSTP1 </it>and <it>EPHX1</it>, two genes encoding xenobiotic metabolizing enzymes, were predictive of response to LVRS. These polymorphisms may identify patients most likely to benefit from LVRS.</p

Identification of the Cis-Acting Elements and Trans-Acting Factors That Mediate Cell-Specific and Thyroid Hormone Stimulation of Growth Hormone Gene Expression

This chapter reviews the physical and biological properties of thyroid hormone receptors and the relationship of the receptor to the avian erythroblastosis virus (AEV) v-erbA gene. The properties of thyroid hormone nuclear receptors derived from studies using GHi and GC cells are described in the chapter. The thyroid hormone receptor is related to the avian erythroblastosis virus v-erbA gene. The AEV—a defective leukemia retrovirus—induces sarcomas and erythroblastosis in vivo and induces the transformation of fibroblasts and erythroblasts to neoplastic phenotypes in vitro. The chapter also reviews the studies in which the rat growth hormone gene was used as a model to identify cis-acting DNA sequences and transacting regulatory proteins that are essential for cell-specific expression and transcriptional stimulation of the gene by the thyroid hormone. The thyroid hormone regulates the growth hormone gene expression at the transcriptional level. A detailed functional and protein-DNA footprint analysis of the elements that are involved in mediating thyroid hormone and cell-specific basal expression of the gene is also presented in the chapter.Peer reviewe

HIV-1 Tat Promotes Kaposi's Sarcoma-Associated Herpesvirus (KSHV) vIL-6-Induced Angiogenesis and Tumorigenesis by Regulating PI3K/PTEN/AKT/GSK-3β Signaling Pathway

Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) is etiologically associated with KS, the most common AIDS-related malignancy. KS is characterized by vast angiogenesis and hyperproliferative spindle cells. We have previously reported that HIV-1 Tat can trigger KSHV reactivation and accelerate Kaposin A-induced tumorigenesis. Here, we explored Tat promotion of KSHV vIL-6-induced angiogenesis and tumorigenesis. Tat promotes vIL-6-induced cell proliferation, cellular transformation, vascular tube formation and VEGF production in culture. Tat enhances vIL-6-induced angiogenesis and tumorigenesis of fibroblasts and human endothelial cells in a chicken chorioallantoic membrane (CAM) model. In an allograft model, Tat promotes vIL-6-induced tumorigenesis and expression of CD31, CD34, SMA, VEGF, b-FGF, and cyclin D1. Mechanistic studies indicated Tat activates PI3K and AKT, and inactivates PTEN and GSK-3β in vIL-6 expressing cells. LY294002, a specific inhibitor of PI3K, effectively impaired Tat's promotion of vIL-6-induced tumorigenesis. Together, these results provide the first evidence that Tat might contribute to KS pathogenesis by synergizing with vIL-6, and identify PI3K/AKT pathway as a potential therapeutic target in AIDS-related KS patients. © 2013 Zhou et al

Primary DNA damage and genetic polymorphisms for CYP1A1, EPHX and GSTM1 in workers at a graphite electrode manufacturing plant

<p>Abstract</p> <p>Background</p> <p>The results of a cross-sectional study aimed to evaluate whether genetic polymorphisms (biomarkers of susceptibility) for <it>CYP1A1</it>, <it>EPHX </it>and <it>GSTM1 </it>genes that affect polycyclic aromatic hydrocarbons (PAH) activation and detoxification might influence the extent of primary DNA damage (biomarker of biologically effective dose) in PAH exposed workers are presented. PAH-exposure of the study populations was assessed by determining the concentration of 1-hydroxypyrene (1OHP) in urine samples (biomarker of exposure dose).</p> <p>Methods</p> <p>The exposed group consisted of workers (n = 109) at a graphite electrode manufacturing plant, occupationally exposed to PAH. Urinary 1OHP was measured by HPLC. Primary DNA damage was evaluated by the alkaline comet assay in peripheral blood leukocytes. Genetic polymorphisms for <it>CYP1A1</it>, <it>EPHX</it> and <it>GSTM1</it> were determined by PCR or PCR/RFLP analysis.</p> <p>Results</p> <p>1OHP and primary DNA damage were significantly higher in electrode workers compared to reference subjects. Moreover, categorization of subjects as normal or outlier highlighted an increased genotoxic risk OR = 2.59 (CI95% 1.32–5.05) associated to exposure to PAH. Polymorphisms in <it>EPHX</it> exons 3 and 4 was associated to higher urinary concentrations of 1OHP, whereas none of the genotypes analyzed (<it>CYP1A1</it>, <it>EPHX</it>, and <it>GSTM1</it>) had any significant influence on primary DNA damage as evaluated by the comet assay.</p> <p>Conclusion</p> <p>The outcomes of the present study show that molecular epidemiology approaches (i.e. cross-sectional studies of genotoxicity biomarkers) can play a role in identifying common genetic risk factors, also attempting to associate the effects with measured exposure data. Moreover, categorization of subjects as normal or outlier allowed the evaluation of the association between occupational exposure to PAH and DNA damage highlighting an increased genotoxic risk.</p

The genetics of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disease caused by the interaction of genetic susceptibility and environmental influences. There is increasing evidence that genes link to disease pathogenesis and heterogeneity by causing variation in protease anti-protease systems, defence against oxidative stress and inflammation. The main methods of genomic research for complex disease traits are described, together with the genes implicated in COPD thus far, their roles in disease causation and the future for this area of investigation

Transformation of glucocorticoid and progesterone receptors to the DNA-binding state

This brief review explores some recent observations relating to the structure of untransformed glucocorticoid and progesterone receptors and the mechanism by which the receptors are transformed to the DNA-binding state. In their molybdate-stabilized, untransformed state, progesterone and glucocorticoid receptors exist as a heteromeric 8-9S complex containing one unit of steroid binding phosphoprotein and one or two units of the 90 kD heat shock protein hsp90. When the receptors are transformed, the steroid-binding protein dissociates from hsp90. In cytosol preparations, temperature-mediated dissociation proceeds much more rapidly in the presence of hormone. The dissociated receptor binds to DNA with high affinity, regardless of whether it is in the hormone-bound or the hormone-free state. These observations raise the possibility that the primary, and perhaps the only, role for the hormone is to promote dissociation of the receptor-hsp90 complex. Molybdate, vanadate, and tungstate inhibit receptor transformation to the DNA-binding form, an effect that appears to reflect the ability of these transition metal oxyanions to stabilize the complex between the steroid receptor and hsp90. By promoting the formation of disulfide bonds, hydrogen peroxide also stabilizes the glucocorticoid receptor-hsp90 complex and prevents receptor transformation. A small, heat-stable factor present in all cytosol preparations inhibits receptor transformation, and, when the factor is removed, glucocorticoid receptors are rapidly transformed. This ubiquitous factor has the physical properties of a metal anion, and it is proposed that molybdate and vanadate affect steroid receptor complexes by interacting with a metal anion-binding site that is normally occupied by this endogenous receptor-stabilizing factor.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38448/1/240350105_ftp.pd