bluuebunny/crossref_metadata_2025 huggingface dataset:
Baicalein Overcomes Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand Resistance via Two Different Cell-Specific Pathways in Cancer Cells but not in Normal Cells
Authors: Taniguchi Hiroya , Yoshida Tatsushi , Horinaka Mano , Yasuda Takashi , Goda Ahmed E. , Konishi Masako , Wakada Miki , Kataoka Keisho , Yoshikawa Toshikazu , Sakai Toshiyuki
Published: October 2008

Tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) is one of the most promising candidates for new cancer therapeutics. A current problem is that some cancers still remain resistant to TRAIL. We show for the first time that a naturally occurring flavonoid, baicalein, overcomes TRAIL resistance in cancer cells. The combination of baicalein and TRAIL effectively induced apoptosis in TRAIL-resistant colon cancer SW480 cells. Baicalein up-regulated the expression of death receptor 5 (DR5) among TRAIL receptors at the mRNA and protein levels. Suppression of this up-regulation with small interfering RNA (siRNA) efficiently reduced the apoptosis induced by TRAIL and baicalein, suggesting that the sensitization was mediated through DR5 induction. Moreover, baicalein also overcame TRAIL resistance with DR5 up-regulation in prostate cancer PC3 cells. Of note, the combination of TRAIL and baicalein hardly induced apoptosis in normal human cells, such as blood cells and hepatocytes. Baicalein increased DR5 promoter activity, and this enhanced activity was diminished by mutation of a CCAAT/enhancer-binding protein homologous protein (CHOP)–binding site in SW480 cells. In SW480 cells, CHOP siRNA blocked both functions of baicalein. CHOP expression was induced by baicalein in SW480 cells; however, in PC3 cells, baicalein scarcely induced CHOP and mutation of the CHOP-binding site did not abrogate the DR5 promoter activation by baicalein. Interestingly, baicalein induced reactive oxygen species (ROS) and a ROS scavenger prevented DR5 expression and TRAIL sensitization in PC3 but not SW480 cells. These results indicate that, using two different pathways, baicalein exposes cancer surveillance of TRAIL and overcomes TRAIL resistance in cancer cells. [Cancer Res 2008;68(21):8918–27]
Bioselection of a Gain of Function Mutation that Enhances Adenovirus 5 Release and Improves Its Antitumoral Potency
Authors: Gros Alena , Martínez-Quintanilla Jordi , Puig Cristina , Guedan Sonia , Molleví David G. , Alemany Ramon , Cascallo Manel
Published: October 2008

Genetic bioselection of a mutagenized Ad5wt stock in human tumor xenografts led us to isolate AdT1, a mutant displaying a large-plaque phenotype in vitro and an enhanced systemic antitumor activity in vivo. AdT1 phenotype correlates with an increased progeny release without affecting total viral yield in different human tumors and cancer-associated fibroblasts. An approach combining hybrid Ad5/AdT1 recombinants and sequencing identified a truncating insertion in the endoplasmic reticulum retention domain of the E3/19K protein (445A mutation) which relocates the protein to the plasma membrane and is responsible for AdT1's enhanced release. E3/19K-445A phenotype does not correlate with the protein's ability to interact with MHC-I or induce apoptosis. Intracellular calcium measurement revealed that the 445A mutation induces extracellular Ca2+ influx, deregulating intracellular Ca2+ homeostasis and inducing membrane permeabilization, a viroporin-like function. E3/19K-445A mutants also display enhanced antitumoral activity when injected both intratumorally and systemically in different models in vivo. Our results indicate that the inclusion of mutation 445A in tumor-selective adenoviruses would be a very powerful tool to enhance their antitumor efficacy. [Cancer Res 2008;68(21):8928–10]
Carcinogen-Induced Gene Promoter Hypermethylation Is Mediated by DNMT1 and Causal for Transformation of Immortalized Bronchial Epithelial Cells
Authors: Damiani Leah A. , Yingling Christin M. , Leng Shuguang , Romo Paul E. , Nakamura Jun , Belinsky Steven A.
Published: October 2008

A better understanding of key molecular changes during transformation of lung epithelial cells could affect strategies to reduce mortality from lung cancer. This study uses an in vitro model to identify key molecular changes that drive cell transformation and the likely clonal outgrowth of preneoplastic lung epithelial cells that occurs in the chronic smoker. Here, we show differences in transformation efficiency associated with DNA repair capacity for two hTERT/cyclin-dependent kinase 4, immortalized bronchial epithelial cell lines after low-dose treatment with the carcinogens methylnitrosourea, benzo(a)pyrene-diolepoxide 1, or both for 12 weeks. Levels of cytosine-DNA methyltransferase 1 (DNMT1) protein increased significantly during carcinogen exposure and were associated with the detection of promoter hypermethylation of 5 to 10 genes in each transformed cell line. Multiple members of the cadherin gene family were commonly methylated during transformation. Stable knockdown of DNMT1 reversed transformation and gene silencing. Moreover, stable knockdown of DNMT1 protein before carcinogen treatment prevented transformation and methylation of cadherin genes. These studies provide a mechanistic link between increased DNMT1 protein, de novo methylation of tumor suppressor genes, and reduced DNA repair capacity that together seem causal for transformation of lung epithelial cells. This finding supports the development of demethylation strategies for primary prevention of lung cancer in smokers. [Cancer Res 2008;68(21):9005–14]
Delocalization of the Microtubule Motor Dynein from Mitotic Spindles by the Human Papillomavirus E7 Oncoprotein Is Not Sufficient for Induction of Multipolar Mitoses
Authors: Nguyen Christine L. , McLaughlin-Drubin Margaret E. , Münger Karl
Published: October 2008

Dynein is a minus end–directed microtubule motor that transports numerous cargoes throughout the cell. During mitosis, dynein motor activity is necessary for the positioning of spindle microtubules and has also been implicated in inactivating the spindle assembly checkpoint. Mutations in dynein motor and/or accessory proteins are associated with human disease, including cancer, and the delocalization of dynein from mitotic spindles has been correlated with an increased incidence of multipolar spindle formation in some cancer cells that contain supernumerary centrosomes. The high-risk human papillomavirus type 16 (HPV16) E7 oncoprotein induces centrosome overduplication and has been shown to cause multipolar mitotic spindle formation, a diagnostic hallmark of HPV-associated neoplasias. Here, we show that HPV16 E7 expression leads to an increased population of mitotic cells with dynein delocalized from the mitotic spindle. This function maps to sequences of HPV16 E7 that are distinct from the region necessary for centrosome overduplication. However, contrary to previous reports, we provide evidence that dynein delocalization by HPV16 E7 is neither necessary nor sufficient to cause the formation of multipolar mitoses. [Cancer Res 2008;68(21):8715–22]
Tnk1/Kos1 Knockout Mice Develop Spontaneous Tumors
Authors: Hoare Sarasija , Hoare Kishalay , Reinhard Mary K. , Lee Young J. , Oh S. Paul , May W. Stratford
Published: October 2008

Tnk1/Kos1 is a non–receptor protein tyrosine kinase implicated in negatively regulating cell growth in a mechanism requiring its intrinsic catalytic activity. Tnk1/Kos1 null mice were created by homologous recombination by deleting the catalytic domain. Both Tnk1+/− and Tnk1−/− mice develop spontaneous tumors, including lymphomas and carcinomas, at high rates [27% (14 of 52) and 43% (12 of 28), respectively]. Tnk1/Kos1 expression is silenced in tumors that develop in Tnk1+/− mice but not in adjacent uninvolved tissue, and silencing occurs in association with Tnk1 promoter hypermethylation. Tissues and murine embryonic fibroblasts derived from Tnk1/Kos1-null mice exhibit proportionally higher levels of basal and epidermal growth factor–stimulated Ras activation that results from increased Ras-guanine exchange factor (GEF) activity. Mechanistically, Tnk1/Kos1 can directly tyrosine phosphorylate growth factor receptor binding protein 2 (Grb2), which promotes disruption of the Grb2-Sos1 complex that mediates growth factor–induced Ras activation, providing dynamic regulation of Ras GEF activity with suppression of Ras. Thus, Tnk1/Kos1 is a tumor suppressor that functions to down-regulate Ras activity. [Cancer Res 2008;68(21):8723–32]
Modification of Cysteine Residue in p65 Subunit of Nuclear Factor-κB (NF-κB) by Picroliv Suppresses NF-κB–Regulated Gene Products and Potentiates Apoptosis
Authors: Anand Preetha , Kunnumakkara Ajaikumar B. , Harikumar Kuzhuvelil B. , Ahn Kwang Seok , Badmaev Vladimir , Aggarwal Bharat B.
Published: October 2008

Picroliv, an iridoid glycoside derived from the plant Picrorhiza kurroa, is used traditionally to treat fever, asthma, hepatitis, and other inflammatory conditions. However, the exact mechanism of its therapeutic action is still unknown. Because nuclear factor-κB (NF-κB) activation plays a major role in inflammation and carcinogenesis, we postulated that picroliv must interfere with this pathway by inhibiting the activation of NF-κB–mediated signal cascade. Electrophoretic mobility shift assay showed that pretreatment with picroliv abrogated tumor necrosis factor (TNF)–induced activation of NF-κB. The glycoside also inhibited NF-κB activated by carcinogenic and inflammatory agents, such as cigarette smoke condensate, phorbol 12-myristate 13-acetate, okadaic acid, hydrogen peroxide, lipopolysaccharide, and epidermal growth factor. When examined for the mechanism of action, we found that picroliv inhibited activation of IκBα kinase, leading to inhibition of phosphorylation and degradation of IκBα. It also inhibited phosphorylation and nuclear translocation of p65. Further studies revealed that picroliv directly inhibits the binding of p65 to DNA, which was reversed by the treatment with reducing agents, suggesting a role for a cysteine residue in interaction with picroliv. Mutation of Cys38 in p65 to serine abolished this effect of picroliv. NF-κB inhibition by picroliv leads to suppression of NF-κB–regulated proteins, including those linked with cell survival (inhibitor of apoptosis protein 1, Bcl-2, Bcl-xL, survivin, and TNF receptor–associated factor 2), proliferation (cyclin D1 and cyclooxygenase-2), angiogenesis (vascular endothelial growth factor), and invasion (intercellular adhesion molecule-1 and matrix metalloproteinase-9). Suppression of these proteins enhanced apoptosis induced by TNF. Overall, our results show that picroliv inhibits the NF-κB activation pathway, which may explain its anti-inflammatory and anticarcinogenic effects. [Cancer Res 2008;68(21):8861–70]
Loss of NKX3.1 Favors Vascular Endothelial Growth Factor-C Expression in Prostate Cancer
Authors: Zhang Heyu , Muders Michael H. , Li Jinping , Rinaldo Francesca , Tindall Donald J. , Datta Kaustubh
Published: October 2008

Decreased levels of the prostate-specific homeobox protein NKX3.1 are correlated with hormone-refractory and metastatic prostate cancer. Thus, it is compelling to define the NKX3.1-regulated genes that may be important for the progression of the advanced stage of the disease. In this study, we showed that vascular endothelial growth factor-C (VEGF-C) is one such target gene of NKX3.1. NKX3.1 inhibited VEGF-C expression in prostate cancer, and the loss of NKX3.1 led to increased VEGF-C expression. Histone deacetylase 1 acted as a corepressor of VEGF-C expression along with NKX3.1. Activated RalA acted in synergy with the loss of NKX3.1 for VEGF-C transcription. Patients with deletions at chromosome 8p21.1-p21.2 as a sole deletion developed lymph node metastasis. Interestingly, the higher expression of VEGF-C in prostate cancer is also correlated with lymph node metastasis. Therefore, regulation of VEGF-C expression by NKX3.1 provides a possible mechanism by which the loss of NKX3.1 protein level leads to lymphangiogenesis in the late stages of advanced prostate cancer. [Cancer Res 2008;68(21):8770–8]
FoxM1B Transcriptionally Regulates Vascular Endothelial Growth Factor Expression and Promotes the Angiogenesis and Growth of Glioma Cells
Authors: Zhang Yujian , Zhang Nu , Dai Bingbing , Liu Mingguang , Sawaya Raymond , Xie Keping , Huang Suyun
Published: October 2008

We previously found that FoxM1B is overexpressed in human glioblastomas and that forced FoxM1B expression in anaplastic astrocytoma cells leads to the formation of highly angiogenic glioblastoma in nude mice. However, the molecular mechanisms by which FoxM1B enhances glioma angiogenesis are currently unknown. In this study, we found that vascular endothelial growth factor (VEGF) is a direct transcriptional target of FoxM1B. FoxM1B overexpression increased VEGF expression, whereas blockade of FoxM1 expression suppressed VEGF expression in glioma cells. Transfection of FoxM1 into glioma cells directly activated the VEGF promoter, and inhibition of FoxM1 expression by FoxM1 siRNA suppressed VEGF promoter activation. We identified two FoxM1-binding sites in the VEGF promoter that specifically bound to the FoxM1 protein. Mutation of these FoxM1-binding sites significantly attenuated VEGF promoter activity. Furthermore, FoxM1 overexpression increased and inhibition of FoxM1 expression suppressed the angiogenic ability of glioma cells. Finally, an immunohistochemical analysis of 59 human glioblastoma specimens also showed a significant correlation between FoxM1 overexpression and elevated VEGF expression. Our findings provide both clinical and mechanistic evidence that FoxM1 contributes to glioma progression by enhancing VEGF gene transcription and thus tumor angiogenesis. [Cancer Res 2008;68(21):8733–42]
Tandem Duplication Producing a Novel Oncogenic BRAF Fusion Gene Defines the Majority of Pilocytic Astrocytomas
Authors: Jones David T.W. , Kocialkowski Sylvia , Liu Lu , Pearson Danita M. , Bäcklund L. Magnus , Ichimura Koichi , Collins V. Peter
Published: October 2008

Brain tumors are the most common solid tumors of childhood, and pilocytic astrocytomas (PA) are the most common central nervous system tumor in 5 to 19 year olds. Little is known about the genetic alterations underlying their development. Here, we describe a tandem duplication of ∼2 Mb at 7q34 occurring in 66% of PAs. This rearrangement, which was not observed in a series of 244 higher-grade astrocytomas, results in an in-frame fusion gene incorporating the kinase domain of the BRAF oncogene. We further show that the resulting fusion protein has constitutive BRAF kinase activity and is able to transform NIH3T3 cells. This is the first report of BRAF activation through rearrangement as a frequent feature in a sporadic tumor. The frequency and specificity of this change underline its potential both as a therapeutic target and as a diagnostic tool. [Cancer Res 2008;68(21):8673–7]
A Key Tyrosine (Y1494) in the β4 Integrin Regulates Multiple Signaling Pathways Important for Tumor Development and Progression
Authors: Dutta Udayan , Shaw Leslie M.
Published: October 2008

Expression of the α6β4 integrin is associated with poor patient prognosis and reduced survival in a variety of human cancers. In recent years, a limited number of in vivo studies have examined the contribution of this integrin receptor to cancer progression and they have revealed that the α6β4 integrin plays a multifaceted role in regulating tumor development and progression. In the current study, we investigated the mechanism by which one tyrosine residue in the β4 subunit cytoplasmic domain, Y1494, contributes to the tumor-promoting functions of the α6β4 integrin in vivo. We show that Y1494 participates in the stimulation of diverse signaling pathways that promote α6β4-dependent tumor growth and invasion. Mutation of Y1494 inhibits the ability of the α6β4 integrin to support anchorage-independent growth in vitro and tumor development and angiogenesis in vivo, a result that mimics the loss of total expression of the β4 subunit. Our results support the hypothesis that Y1494 regulates α6β4-dependent anchorage-independent growth through activation of the extracellular signal-regulated kinase 1/2 signaling pathway, and invasion through the combined activation of phosphatidylinositol 3-kinase and Src. Collectively, our results identify Y1494 as a major regulatory site for signaling from the α6β4 integrin to promote tumor development and progression. [Cancer Res 2008;68(21):8779–87]
Association Study of Prostate Cancer Susceptibility Variants with Risks of Invasive Ovarian, Breast, and Colorectal Cancer
Authors: Song Honglin , Koessler Thibaud , Ahmed Shahana , Ramus Susan J. , Kjaer Susanne Krüger , DiCioccio Richard A. , Wozniak Eva , Hogdall Estrid , Whittemore Alice S. , McGuire Valerie , Ponder Bruce A.J. , Turnbull Clare , Hines Sarah , Rahman Nazneen ,   The Breast Cancer Susceptibility Collaboration (UK), Eeles Rosalind A. , Easton Douglas F. , Gayther Simon A. , Dunning Alison M. , Pharoah Paul D.P.
Published: October 2008

Several prostate cancer susceptibility loci have recently been identified by genome-wide association studies. These loci are candidates for susceptibility to other epithelial cancers. The aim of this study was to test these tag single nucleotide polymorphisms (SNP) for association with invasive ovarian, colorectal, and breast cancer. Twelve prostate cancer–associated tag SNPs were genotyped in ovarian (2,087 cases/3,491 controls), colorectal (2,148 cases/2,265 controls) and breast (first set, 4,339 cases/4,552 controls; second set, 3,800 cases/3,995 controls) case-control studies. The primary test of association was a comparison of genotype frequencies between cases and controls, and a test for trend stratified by study where appropriate. Genotype-specific odds ratios (OR) were estimated by logistic regression. SNP rs2660753 (chromosome 3p12) showed evidence of association with ovarian cancer [per minor allele OR, 1.19; 95% confidence interval (95% CI), 1.04–1.37; Ptrend = 0.012]. This association was stronger for the serous histologic subtype (OR, 1.29; 95% CI, 1.09–1.53; P = 0.003). SNP rs7931342 (chromosome 11q13) showed some evidence of association with breast cancer (per minor allele OR, 0.95; 95% CI, 0.91–0.99; Ptrend = 0.028). This association was somewhat stronger for estrogen receptor–positive tumors (OR, 0.92; 95% CI, 0.87–0.98; P = 0.011). None of these tag SNPs were associated with risk of colorectal cancer. In conclusion, loci associated with risk of prostate cancer may also be associated with ovarian and breast cancer susceptibility. However, the effects are modest and warrant replication in larger studies. [Cancer Res 2008;68(21):8837–42]
Targeting Melanoma Growth and Metastasis with Systemic Delivery of Liposome-Incorporated Protease-Activated Receptor-1 Small Interfering RNA
Authors: Villares Gabriel J. , Zigler Maya , Wang Hua , Melnikova Vladislava O. , Wu Hong , Friedman Ran , Leslie Michael C. , Vivas-Mejia Pablo E. , Lopez-Berestein Gabriel , Sood Anil K. , Bar-Eli Menashe
Published: October 2008

The thrombin receptor [protease-activated receptor-1 (PAR-1)] is overexpressed in highly metastatic melanoma cell lines and in patients with metastatic lesions. Activation of PAR-1 leads to cell signaling and up-regulation of genes involved in adhesion, invasion, and angiogenesis. Herein, we stably silence PAR-1 through the use of lentiviral short hairpin RNA and found significant decreases in both tumor growth (P < 0.01) and metastasis (P < 0.001) of highly metastatic melanoma cell lines in vivo. The use of viruses for therapy is not ideal as it can induce toxic immune responses and possible gene alterations following viral integration. Therefore, we also used systemic delivery of PAR-1 small interfering RNA (siRNA) incorporated into neutral liposomes [1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC)] to decrease melanoma growth and metastasis in vivo. Significant decreases in tumor growth, weight, and metastatic lung colonies (P < 0.001 for all) were found in mice treated with PAR-1 siRNA-DOPC. The in vivo effects of PAR-1 on invasion and angiogenesis were analyzed via immunohistochemistry. Concomitant decreases in vascular endothelial growth factor, interleukin-8, and matrix metalloproteinase-2 expression levels, as well as decreased blood vessel density (CD31), were found in tumor samples from PAR-1 siRNA-treated mice, suggesting that PAR-1 is a regulator of melanoma cell growth and metastasis by affecting angiogenic and invasive factors. We propose that siRNA incorporated into DOPC nanoparticles could be delivered systemically and used as a new modality for melanoma treatment. [Cancer Res 2008;68(21):9078–86]
Activation of Matrix Metalloproteinase-2 (MMP-2) by Membrane Type 1 Matrix Metalloproteinase through an Artificial Receptor for ProMMP-2 Generates Active MMP-2
Authors: Nishida Yuki , Miyamori Hisashi , Thompson Erik W. , Takino Takahisa , Endo Yoshio , Sato Hiroshi
Published: October 2008

The suggested model for pro-matrix metalloproteinase-2 (proMMP-2) activation by membrane type 1 MMP (MT1-MMP) implicates the complex between MT1-MMP and tissue inhibitor of MMP-2 (TIMP-2) as a receptor for proMMP-2. To dissect this model and assess the pathologic significance of MMP-2 activation, an artificial receptor for proMMP-2 was created by replacing the signal sequence of TIMP-2 with cytoplasmic/transmembrane domain of type II transmembrane mosaic serine protease (MSP-T2). Unlike TIMP-2, MSP-T2 served as a receptor for proMMP-2 without inhibiting MT1-MMP, and generated TIMP-2–free active MMP-2 even at a low level of MT1-MMP. Thus, MSP-T2 did not affect direct cleavage of the substrate testican-1 by MT1-MMP, whereas TIMP-2 inhibited it even at the level that stimulates proMMP-2 processing. Expression of MSP-T2 in HT1080 cells enhanced MMP-2 activation by endogenous MT1-MMP and caused intensive hydrolysis of collagen gel. Expression of MSP-T2 in U87 glioma cells, which express a trace level of endogenous MT1-MMP, induced MMP-2 activation and enhanced cell-associated protease activity, activation of extracellular signal–regulated kinase, and metastatic ability into chick embryonic liver and lung. MT1-MMP can exert both maximum MMP-2 activation and direct cleavage of substrates with MSP-T2, which cannot be achieved with TIMP-2. These results suggest that MMP-2 activation by MT1-MMP potentially amplifies protease activity, and combination with direct cleavage of substrate causes effective tissue degradation and enhances tumor invasion and metastasis, which highlights the complex role of TIMP-2. MSP-T2 is a unique tool to analyze physiologic and pathologic roles of MMP-2 and MT1-MMP in comparison with TIMP-2. [Cancer Res 2008;68(21):9096–104]
CCCTC-Binding Factor Confines the Distal Action of Estrogen Receptor
Authors: Chan Chang S. , Song Jun S.
Published: October 2008

Distal enhancers have recently emerged as a common mode of gene regulation for several transcription factors, including estrogen and androgen receptors, the two key regulators of breast and prostate cancer major subtypes. Despite the rapid success in genome-wide annotation of estrogen receptor-α (ERα) binding sites in cell lines, the precise mechanism governing the gene-to-enhancer association is still unknown and no quantitative model that can predict the estrogen responsiveness of genes has been hitherto proposed. This article presents an integrative genomics approach to construct a predictive model that can explain more than 70% of estrogen-induced expression profiles. The proposed method combines a recent map of the insulator protein CCCTC-binding factor (CTCF) with previous ER location studies and expression profiling in the presence of the translation inhibitor cycloheximide, providing evidence that CTCF partitions the human genome into distinct ER-regulatory blocks. It is shown that estrogen-responsive genes with a decreased transcription level (down-regulated genes) have a markedly different relative distribution of ER binding sites compared with those with an increased transcription level (up-regulated genes). Finally, Bayesian belief networks are constructed to quantify the effects of ER-binding distance from genes as well as the insulating effects of CTCF on the estrogen responsiveness of genes. This work thus represents a stride toward understanding and predicting the distal activities of steroid hormone nuclear receptors. [Cancer Res 2008;68(21):9041–9]
Aurora Kinase A Inhibition Leads to p73-Dependent Apoptosis in p53-Deficient Cancer Cells
Authors: Dar Altaf A. , Belkhiri Abbes , Ecsedy Jeffrey , Zaika Alexander , El-Rifai Wael
Published: October 2008

We investigated the role of Aurora kinase A (AURKA) in regulating p73-dependent apoptosis using the p53-deficient cancer cell lines H1299, TE7, and HCT116p53−/−. Overexpression of AURKA led to down-regulation of the TAp73-induced activation of the p53/p73-dependent luciferase reporter plasmid (pG13-luc). The reduction in the TAp73 transcription activity was confirmed by measuring the activity of luciferase reporters for p21/WAF1, and PUMA. The siRNA knockdown of endogenous AURKA reversed these effects and Western blot analysis showed a significant increase in the protein level of TAp73 and its downstream transcription targets, PUMA, NOXA, and p21/WAF1. The coexpression of AURKA together with TAp73 inhibited the activation of the pG13-luc, PUMA-luc, and p21/WAF1-luc reporter plasmids with reduction in the protein levels of TAp73 transcription targets. Treatment with AURKA-selective small molecule inhibitor MLN8054 led to a significant increase in the activities of pG13-luc, PUMA-luc, and p21/WAF1-luc reporter plasmids. This effect was accompanied by a significant increase in the mRNA and protein levels of several TAp73 transcription targets: p21/WAF1, PUMA, and NOXA. Flow cytometry cell cycle analysis, after MLN8054 treatment, showed more than a 2-fold increase in cell death. The apoptotic outcome was corroborated by showing an increase in cleaved caspase-3 protein levels by Western blot. Using terminal deoxynucleotidyl-transferase–mediated dUTP nick-end labeling assay, we showed that the expression of dominant-negative mutant TAp73 expression plasmid (p73DD) counteracted the MLN8054-induced cell death. Taken together, our results indicate that AURKA regulates TAp73-dependent apoptosis and highlight the potential of the AURKA inhibitor MLN8054 in treating cancers that are defective in p53 signaling. [Cancer Res 2008;68(21):8998–9004]
Efficacy of Biologicals in the Treatment of Rheumatoid Arthritis
Authors: Venkateshan S.P. , Sidhu S. , Malhotra S. , Pandhi P.
Published: October 2008

Rheumatoid arthritis (RA) is a chronic multisystem disease. A characteristic feature of RA is persistent inflammatory synovitis, usually involving the peripheral joints in a symmetric distribution. The prevalence of RA is approximately 0.8% of the population (range: 0.3–2.1%); women are affected approximately 3 times more often than men. The current therapeutic approach is to start a disease-modifying agent early in the illness to prevent eventual joint damage. Older disease-modifying anti-rheumatic drugs include methotrexate, sulphasalazine and hydroxychloroquine. Newer ones such as leflunomide and cyclosporin are also used. A recent advance in the management of rheumatoid arthritis is the use of biological agents, which block certain key molecules involved in the pathogenesis of the illness. They include tumour-necrosis-factor-α-blocking agents such as infliximab, etanercept and adalimumab, the anti-CD-20 agent, rituximab, and CTLA-4 Ig abatacept. The present study was planned with the aim of evaluating the efficacy of such newer biological therapies in refractory RA at various time points. Databases including Medline, Embase and the Cochrane Library were searched for all relevant studies up to January 2007. A total of 26 studies were included in present meta-analysis. The method of DerSimonian and Laird [Control Clin Trials 1986;7:177–188] was used to calculated a pooled odds ratio (OR) for the American College of Rheumatology (ACR) criteria 20, 50 and 70, at 24, 54 and 96 weeks. The overall pooled OR were found to be significantly more than the placebo at all 3 time points for all 3 criteria (ACR 20, 50 70). In conclusion, biologicals as a group are highly effective in the treatment of RA. Biologicals were efficacious both in treatment naïve and methotrexate-refractory patients.
Meeting the Challenges of Opioid-Induced Constipation in Chronic Pain Management – A Novel Approach
Authors: Reimer Karen , Hopp Michael , Zenz Michael , Maier Christoph , Holzer Peter , Mikus Gerd , Bosse Bjoern , Smith Kevin , Buschmann-Kramm Catharina , Leyendecker Petra
Published: October 2008

Opioid analgesics are the cornerstone of pain management for moderate-to-severe cancer pain and, increasingly, chronic noncancer pain. Despite proven analgesic efficacy, the use of opioids is commonly associated with frequently dose-limiting constipation that seriously impacts on patients’ quality of life. Agents currently used to manage opioid-induced constipation (OIC), such as laxatives, do not address the underlying opioid receptor-mediated cause of constipation and are often ineffective. A significant need therefore exists for more effective treatment options. A novel approach for selectively and locally antagonizing the gastrointestinal effects of opioids involves the coadministration of a μ-opioid receptor antagonist with negligible systemic availability, such as oral naloxone. Combination therapy with prolonged-release (PR) oxycodone plus PR naloxone has been shown to provide effective analgesia while preventing or reducing constipation. The current article highlights this novel strategy in its potential to significantly improve the quality of life of patients suffering from chronic pain, affording patients the benefit of full analgesia, without the burden of OIC.
Optimization of Decision Making in Multilayer Networks: The Role of Locus Coeruleus
Authors: Shea-Brown Eric , Gilzenrat Mark S. , Cohen Jonathan D.
Published: October 2008

Previous theoretical work has shown that a single-layer neural network can implement the optimal decision process for simple, two-alternative forced-choice (2AFC) tasks. However, it is likely that the mammalian brain comprises multilayer networks, raising the question of whether and how optimal performance can be approximated in such an architecture. Here, we present theoretical work suggesting that the noradrenergic nucleus locus coeruleus (LC) may help optimize 2AFC decision making in the brain. This is based on the observations that neurons of the LC selectively fire following the presentation of salient stimuli in decision tasks and that the corresponding release of norepinephrine can transiently increase the responsivity, or gain, of cortical processing units. We describe computational simulations that investigate the role of such gain changes in optimizing performance of 2AFC decision making. In the tasks we model, no prior cueing or knowledge of stimulus onset time is assumed.

Performance is assessed in terms of the rate of correct responses over time (the reward rate). We first present the results of a single-layer model that accumulates (integrates) sensory input and implements the decision process as a threshold crossing. Gain transients, representing the modulatory effect of the LC, are driven by separate threshold crossings in this layer. We optimize over all free parameters to determine the maximum reward rate achievable by this model and compare it to the maximum reward rate when gain is held fixed. We find that the dynamic gain mechanism yields no improvement in reward for this single-layer model.

We then examine a two-layer model, in which competing sensory accumulators in the first layer (capable of implementing the task relevant decision) pass activity to response accumulators in a second layer. Again, we compare a version in which threshold crossing in the first (decision) layer elicits an LC response (and a concomitant increase in gain) with a fixed-gain version of the model. Here, we find that gain transients modeling the LC phasic response yield an improvement in reward rate of 12% to 24%. Furthermore, we show that the timing characteristics of these gain transients agree with observations concerning LC firing patterns reported in recent experimental studies. This provides converging evidence for the hypothesis that the LC optimizes processes underlying 2AFC decision making in multilayer networks.
Optimal Approximation of Signal Priors
Authors: Hyvärinen Aapo
Published: October 2008

In signal restoration by Bayesian inference, one typically uses a parametric model of the prior distribution of the signal. Here, we consider how the parameters of a prior model should be estimated from observations of uncorrupted signals. A lot of recent work has implicitly assumed that maximum likelihood estimation is the optimal estimation method. Our results imply that this is not the case. We first obtain an objective function that approximates the error occurred in signal restoration due to an imperfect prior model. Next, we show that in an important special case (small gaussian noise), the error is the same as the score-matching objective function, which was previously proposed as an alternative for likelihood based on purely computational considerations. Our analysis thus shows that score matching combines computational simplicity with statistical optimality in signal restoration, providing a viable alternative to maximum likelihood methods. We also show how the method leads to a new intuitive and geometric interpretation of structure inherent in probability distributions.
Stimulus Representation and the Timing of Reward-Prediction Errors in Models of the Dopamine System
Authors: Ludvig Elliot A. , Sutton Richard S. , Kehoe E. James
Published: October 2008

The phasic firing of dopamine neurons has been theorized to encode a reward-prediction error as formalized by the temporal-difference (TD) algorithm in reinforcement learning. Most TD models of dopamine have assumed a stimulus representation, known as the complete serial compound, in which each moment in a trial is distinctly represented. We introduce a more realistic temporal stimulus representation for the TD model. In our model, all external stimuli, including rewards, spawn a series of internal microstimuli, which grow weaker and more diffuse over time. These microstimuli are used by the TD learning algorithm to generate predictions of future reward. This new stimulus representation injects temporal generalization into the TD model and enhances correspondence between model and data in several experiments, including those when rewards are omitted or received early. This improved fit mostly derives from the absence of large negative errors in the new model, suggesting that dopamine alone can encode the full range of TD errors in these situations.
Genetic diversity in the gecko Tarentola mauritanica within the Iberian Peninsula
Authors: Harris David James , Perera Ana
Published: October 2008

The Mediterranean gecko Tarentola mauritanica is one of the most abundant reptile species in the western Mediterranean Basin. We use mitochondrial DNA sequences, 12sRNA and 16sRNA, to analyse the patterns of distribution in the Iberian Peninsula. The results show three well defined lineages. The first one, already known to be widespread throughout Europe, is distributed along the eastern coast and southern areas of the Iberian Peninsula. The second one, endemic to the Iberian Peninsula, is widely found in central regions; and the third lineage, found so far only in two southern localities is unrelated to the other Iberian lineages, but rather to a Northern Moroccan clade. The genetic variability found within the Iberian haplogroup and the existence of a single haplotype within the European lineage suggests a complex pattern of rapid radiations and anthropogenic introductions. The third clade seems to be the result of a natural colonization from North Africa. All the data indicate that T. mauritanica is a species complex. The Iberian Peninsula, due to its geological complex history, appears to be both a hotspot and a melting pot of biodiversity, with several studies of diverse herpetofauna indicating that cryptic species occur there. More studies of additional species will be needed to develop a comparative phylogeographic framework for the region.
Polyandry in Podocnemis unifilis (Pleurodira; Podocnemididae), the vulnerable yellow-spotted Amazon River turtle
Authors: Fantin Cleiton , Farias Izeni Pires , Monjeló Luiz Alberto dos Santos , Viana Luciana Santos
Published: October 2008

We used eight microsatellite loci to investigate the mating system in P. unifilis. DNA samples were collected from 66 hatchlings sampled from six nests on a central Amazon River beach near Barreirinha, Amazonas, Brazil. We found that P. unifilis females exhibited a promiscuous mating system (polyandry) with all nests being fathered by at least two males. The presence of multiple males contributing to each clutch was ascertained by the presence of at least two extra alleles in multilocus genotypes in each nest. Our data demonstrate that polyandry seems to be the prevalent system of mating in this endangered species.
Extreme reduction in body size and reproductive output associated with sandy substrates in two anuran species
Authors: Marangoni Federico , Gomez-Mestre Iván , Tejedo Miguel
Published: October 2008

Geographic variation in body size and reproductive traits has been reported in a wide range of organisms, including amphibians. Most studies have focused on latitudinal and/or altitudinal variation where differences in temperature and duration of the growing season are the main causes for population divergence. We describe a steep variation in body size and reproductive traits in two anuran species in southwestern Spain, associated with changes in the geological substrate. Pelobates cultripes and Bufo calamita (= Epidalea calamita) drastically reduced their size (a 71.6% and 76.1% reduction in body mass for P. cultripes and B. calamita, respectively) in just about 60 km. This extreme size reduction was more pronounced at the boundary between two different geological substrates (hercinic and sandy soil). Mean clutch mass, egg size, and clutch size were all smaller in B. calamita populations in the sandy environment. Likewise, clutch mass and egg size were both smaller in sandy P. cultripes populations. We observed a negative correlation between size-adjusted fecundity and egg size for both species, suggesting the existence of a reproductive trade-off that could explain the differences in reproductive allocation between populations and species. In P. cultripes, small-bodied populations had relatively higher fecundities and smaller eggs than large-bodied ones, whereas in B. calamita populations from the sandy area we found both populations with high fecundity and small eggs, and populations with low fecundity and large eggs. Common environmental effects associated with the sandy substrate produce a similar reduction in size in both toad species.
Seasonal changes in reproductive output of a year-round nesting population of the green turtle Chelonia mydas at Huyong Island, Thailand
Authors: Yasuda Tohya , Kittiwattanawong Kongkiat , Klom-in Winai , Arai Nobuaki
Published: October 2008

For the vast majority of reptiles, low temperature is a major constraint on reproduction. However, continuous reproduction is not always observed even in equatorial climates. In the present study, we examined the reproductive output of green turtles in a year-round nesting population on Huyong Island, Thailand. From 1996 to 2007, 121 females were identified. Because individual turtles nest several times within a season, we defined the nesting season of an individual as the month during which the first nesting activity was detected. We found a significant difference in clutch frequency among months. However, there were no significant relationships during the nesting period between clutch frequency and environmental parameters such as mean daily air temperature, precipitation and maximum wind speed. Although we could not identify the specific factors, our findings suggest that environmental factors may regulate seasonal variation in reproductive output even in the tropics.
Typhlophis ayarzaguenai Señaris, 1998 is a junior synonym of Typhlophis squamosus (Schlegel, 1839)
Authors: Kok Philippe , Fuenmayor Gilson Rivas
Published: October 2008

In 1839, Schlegel described Typhlophis squamosus on the basis of a single specimen from Cayenne, French Guiana. Since then the species has been reported from Brazil, Guyana and Suriname. Relying only on the original description and a subsequent short description of the holotype of T. squamosus by Boulenger in 1893, Señaris described T. ayarzaguenai from Venezuela in 1998. Señaris' description of T. ayarzaguenai contains several errors and discrepancies and we argue that our observations justify the consideration of T. ayarzaguenai as a junior synonym of T. squamosus. The genus Typhlophis thus remains monotypic and T. squamosus is a widespread species in the Guiana Shield.
Interactions between freshwater mussels and newts: a novel form of parasitism?
Authors: Engel Edmée , Groh Klaus , Griffiths Richard , Wood Laura , Schley Laurent
Published: October 2008

Small freshwater mussels are sometimes found attached to the toes of aquatic phase amphibians, but the ecological implications of this interspecific relationship are unknown. Toe condition and mussel presence were recorded for newts caught in 37 ponds in Luxembourg between March and June 2007. All four local newt species were affected (Lissotriton helveticus, L. vulgaris, Mesotriton alpestris and Triturus cristatus), primarily by the mussel Sphaerium nucleus but also by Pisidium subtruncatum. Mussel attachment was observed in three ponds, with a particularly high occurrence in one pond, where 23% of newts were affected and significantly more toes were damaged than in other ponds. Mussels caused local tissue and bone damage to their host and may interfere with egg-laying. Twenty-two newts with attached mussels were observed in aquaria for up to 3 days: 13 mussels detached when the newt's toe fell off and nine remained attached. If the mussels benefit from the interaction through, for example, enhanced dispersal then the relationship between the two taxa represents a novel form of parasitism.
Short-term changes in dorsal reflectance for background matching in Ornate Tree Lizards (Urosaurus ornatus)
Authors: Hamilton Paul , Sullivan Brian , Gaalema Diann
Published: October 2008

Some lizards are thought to exhibit short-term changes in color to match their background, but this ability has not been verified empirically. We tested the hypothesis that lizards will change dorsal reflectance over a series of days to match their backgrounds. We housed male and female Ornate Tree Lizards (Urosaurus ornatus) for five days in aquaria painted to match environmental extremes in substrate reflectance. Standardized photographs were taken each day yielding dorsal percent reflectance values. After the first day, reflectance of lizards changed significantly to more closely match their backgrounds; this effect became more pronounced through the fifth and final day of the experiment.
Links between Tropical Pacific SST and Cholera Incidence in Bangladesh: Role of the Western Tropical and Central Extratropical Pacific
Authors: Cash Benjamin A. , Rodó Xavier , Kinter James L.
Published: October 2008

Recent studies arising from both statistical analysis and dynamical disease models demonstrate a link between the incidence of cholera, a paradigmatic waterborne bacterial illness endemic to Bangladesh, and the El Niño–Southern Oscillation (ENSO). The physical significance of this relationship was investigated by examining links between the regional climate of Bangladesh and western Pacific sea surface temperatures (SST) associated with ENSO using a pacemaker configuration of the Center for Ocean–Land–Atmosphere Studies atmospheric general circulation model. The global SST response to ENSO SST anomalies in the western Pacific alone is found to be relatively weak and unrealistic when compared to observations, indicating that the global response to ENSO is driven primarily by anomalies in the central and eastern tropical Pacific. Despite the weak global response to western Pacific SST anomalies, however, a signal is found in summer rainfall over India and Bangladesh. Specifically, reduced rainfall typically follows winter El Niño events. In the absence of warm SST anomalies in the eastern Pacific, cold anomalies in the western Pacific produce a La Niña–like response in the model circulation. Cold SST anomalies suppress convection over the western Pacific. Large-scale convergence shifts into the eastern Indian Ocean and modifies the summer monsoon circulation over India and Bangladesh.

The probabilistic relationship between Bangladesh rainfall and SST is also explored using a nonparametric statistical technique. Decreased rainfall is strongly associated with cold SST in the western Pacific, while associations between SST and enhanced rainfall are substantially weaker. Also found are strong associations between rainfall and SST in the Indian Ocean in the absence of differences in forcing from the western Pacific. It thus appears that the Indian Ocean may represent an independent source of predictability for the monsoon and cholera risk. Likewise, under certain circumstances, the western Pacific may also exert a significant influence on Bangladesh rainfall and cholera risk.
Role of Air–Sea Interaction in the Long Persistence of El Niño–Induced North Indian Ocean Warming*
Authors: Du Yan , Xie Shang-Ping , Huang Gang , Hu Kaiming
Published: October 2008

El Niño induces a basin-wide increase in tropical Indian Ocean (TIO) sea surface temperature (SST) with a lag of one season. The north IO (NIO), in particular, displays a peculiar double-peak warming with the second peak larger in magnitude and persisting well through the summer. Motivated by recent studies suggesting the importance of the TIO warming for the Northwest Pacific and East Asian summer monsoons, the present study investigates the mechanisms for the second peak of the NIO warming using observations and general circulation models. This analysis reveals that internal air–sea interaction within the TIO is key to sustaining the TIO warming through summer. During El Niño, anticyclonic wind curl anomalies force a downwelling Rossby wave in the south TIO through Walker circulation adjustments, causing a sustained SST warming in the tropical southwest IO (SWIO) where the mean thermocline is shallow. During the spring and early summer following El Niño, this SWIO warming sustains an antisymmetric pattern of atmospheric anomalies with northeasterly (northwesterly) wind anomalies north (south) of the equator. Over the NIO as the mean winds turn into southwesterly in May, the northeasterly anomalies force the second SST peak that persists through summer by reducing the wind speed and surface evaporation. Atmospheric general circulation model experiments show that the antisymmetric atmospheric pattern is a response to the TIO warming, suggestive of their mutual interaction. Thus, ocean dynamics and Rossby waves in particular are important for the warming not only locally in SWIO but also on the basin-scale north of the equator, a result with important implications for climate predictability and prediction.