bluuebunny/crossref_metadata_2025 huggingface dataset:
GENE REGULATION IN ADAPTIVE EVOLUTION
Authors: McDonald John F. , Ayala Francisco J.
Published: August 2008

It has recently been suggested that gene regulation may play a critical role in adaptive evolution. However, gene regulation has proved to be most refractory to experimental investigation in multicellular organisms. Using specially constructed stocks of Drosophila melanogaster, we have demonstrated the following. (1) The existence in natural populations of ample variation in regulatory genes that modify the activity of alcohol dehydrogenase (ADH), an enzyme coded by a structural gene locus, Adh, located on the second chromosome; the regulatory genes are located on the third chromosome, and thus are not adjacent to the structural locus. (2) The regulatory genes act not by means of post-transcriptional or post-translational modification of the gene product, but rather by controlling the number of ADH molecules; this is consistent with the hypothesis of gene regulation by means of macromolecules specifically binding at control sites adjacent to the structural gene locus. (3) The variation in regulatory genes is adaptively significant; adaptation to higher levels of environmental alcohol takes place not by changes in the Adh structural locus, but by changes in regulatory genes that control the number of ADH molecules in the organisms. Our results provide direct evidence of the importance of gene regulation in eucaryotic evolution.
EFFECT OF FUNGICIDE FOLPET ON GROWTH AND CHROMOSOMES OF HUMAN LYMPHOID CELL LINES
Authors: Sirianni S. R. , Huang C. C.
Published: August 2008

One normal human lymphoid cell line was treated continuously with the fungicide Folpet (N-trichloromethylthio-phthalimide) at 0.5, 1, 2, and 4 μg/ml of media and one Burkitt cell line was pulse-treated with the same compound for 15 min at 2.5, 5, 10, and 15 μg/ml. Various times after treatment, cell viability counts and chromosome analyses were made. Severe cell growth inhibition and an increase in chromosome aberrations were observed in both cell lines. There were two types of induced chromosome aberrations. Aberrations type A appeared in cultures treated with lower doses and were characterized by chromosome or chromatid gaps and breaks and also infrequently seen exchanges and dicentrics. In the later stages of the experiment, the rate of growth and aberrations returned to control levels. Chromosome aberrations type B appeared in early samples of cultures treated with higher doses. The whole complement of chromosomes was affected. The aberrations included chromosome stickiness, despiralization and pulverization. The cultures died off within two days.
A TENTATIVE IDENTIFICATION OF CHROMOSOMES PRESENT IN TETRAPLOID TRITICALE BASED ON HETEROCHROMATIC BANDING PATTERNS
Authors: Gustafson J. P. , Krolow K. D.
Published: August 2008

Three tetraploid triticales were analysed by C-banding techniques in order to establish their chromosome constitutions. All three tetraploid triticales contained seven rye chromosomes with the banding pattern of Secale cereale L. A mixture of A- and B-genome chromosomes from Triticum turgidum L. constituted the wheat genome present in the tetraploid triticales. Triticale Trc 4x3 contained 1A, 2B, 3A, 4A, 5B, 6A, and 7B. Triticale Trc 4x2 contained 1A, 2B, 3B, 4B, 5B, 6A, and 7B, while triticale Trc 4x5 contained 1A, 2B, 3B, 4A, 5A, 6A, and 7B. The reliability of the staining technique is subject to errors in identification, which are discussed.
VARIATION OF POLLEN SIZE IN TWO POLYPLOID COMPLEXES: MERCURIALIS ANNUA AND PHYLLANTHUS ODONTADENIUS
Authors: Médus J.
Published: August 2008

Data processing of the P axis measurements of pollen grains from Mercurialis annua L.s.l. and Phyllanthus odontadenius Mull.-Arg.s.l. complexe was undertaken on the basis of a multidimensional analysis program (factorial correspondences analysis). By means of this method a relationship was proposed between the variation in pollen size and the distributional pattern of the cytotypes examined. Moreover, upon comparing some other results with those from the present essay it seems reasonable that a distinction be made between processes controlling the presence or absence of pollen features and those controlling their balance.
INDUCTION OF GENE POOL DIFFERENTIATION INDROSOPHILA MELANOGASTER
Authors: Alahiotis S. , Pelecanos M.
Published: August 2008

The selective effect of the ecological parameter "food medium" upon the gene pool of Drosophila melanogaster was investigated in nine cage populations by estimating the allozyme frequencies of the a-Gpdh and Adh loci. The differentiation observed was found to depend dramatically upon the action of the above mentioned environmental factor. Small differences may be mainly attributed to the effect of the differing genetic backgrounds of each gene pool. When the environment was restrictive, a dramatic gene pool differentiation was observed. A discussion is provided bearing upon the observed induction of a process which involves large groups of coadapted genes upon which selection actually acts. Furthermore, the role of nutrition, and especially yeast, was found to have a profound effect upon the observed genetic differentiation of the gene pool of D. melanogaster.
LACTATE DEHYDROGENASE IN RABBIT OOCYTES AND EGGS
Authors: Peacock Timothy A. R. , Browder Leon W. , Schultz Gilbert A.
Published: August 2008

It has recently been reported that the rabbit oocyte lactate dehydrogenase (LDH) isozyme pattern shifts dramatically at ovulation. We have determined that both ovarian oocytes and ovulated eggs have predominantly LDH-5 with minor amounts of LDH-4. Therefore, no change occurs at ovulation. When oocytes or eggs are not treated to remove follicle cells, all five LDH isozymes are observed. Isolated follicle cells also have five isozymes. We suggest that failure to remove follicle cells can cause altered LDH isozyme patterns and may account for conflicting results in the literature.
The Distribution of Yin-Deficient Symptoms and Their Relationship on Survival Rate in Cancer Patients with Yin-Deficiency
Authors: Lin Shu-Chuan , Chen Ming-Feng , Li Tsai-Chung , Hsieh Yu-Ho , Liu Shwu-Jiuan
Published: August 2008

Yin-Deficiency (YD), representing a status of the human body under lack of nutrition and fluid in traditional Chinese medicine, is commonly seen in late stage of cancer patients. It is not known whether the severity of YD related symptoms/signs can predict the survival rate of cancer patients. This study evaluated the distribution of Yin-deficiency symptoms/signs (YDS) in cancer patients with YD, and investigated whether the severity of YDS can predict the survival rate of cancer patients with YD. From 5 January 2007 to 5 May 2007, we selected 43 cancer patients with diagnosis of YD from hospitalized patients and outpatients. The severity of YD was evaluated by a questionnaire. We further estimated the cumulative probabilities of the survival rates over 4 months since the start of study by the Kaplan-Meier product-limit method, and compared the differences among groups with various severities in each symptom/sign with the use of the log-rank test. The results revealed that, the 3 most common YDS were sleeplessness with annoyance, less or non-coated tongue with or without redness and dry mouth. In the survival rate analysis, only 2 parameters, rapidly small pulse (p = 0.002) and less-or non-coated tongue with paleness (p = 0.017), were found to be related to the decrease of cancer patients with YD. This suggests that, both rapidly small pulse and less-or non-coated tongue without redness may be used as predictors for the estimation of survival rate in cancer patients with YD.
The Antithrombotic Effect of Borneol Related to Its Anticoagulant Property
Authors: Li Yan-Hong , Sun Xiao-Ping , Zhang Yin-Qing , Wang Ning-Sheng
Published: August 2008

Borneol is consumed excessively in China and Southeast Asian countries particularly in combined formula for preventing cardiovascular disease, but few studies were conducted on its effects on thrombosis. In this study, the antithrombotic and antiplatelet activities of borneol were investigated on thrombosis in vivo and on platelet aggregation ex-vivo. In addition, the coagulation parameters and influence on fibrinolytic activity were also assessed. The results showed that borneol had concentration dependent inhibitory effects on arterio-venous shunt and venous thrombosis but no effect on ADP and AA-induced platelet aggregation. Meanwhile, borneol prolonged the coagulation parameters for prothrombin time (PT) and thrombin time (TT), but did not show any fibrinolytic activity. It suggested that the antithrombotic activity of borneol and its action in combined formula for preventing cardiovascular diseases might be due to anticoagulant activity rather than antiplatelet activity.
Green Tea Extract Enhances the Selective Cytotoxic Activity of Zizyphus jujuba Extracts in HepG2 Cells
Authors: Huang Xuedan , Kojima-Yuasa Akiko , Xu Shenghui , Norikura Toshio , Kennedy David Opare , Hasuma Tadayoshi , Matsui-Yuasa Isao
Published: August 2008

Anticarcinogenic effects attributed to phytochemicals may be based on synergistic, additive, or antagonistic interactions of many compounds. In our previous study, we demonstrated that the chloroform fraction ( CHCl 3- F ) from Z. jujuba has anticancer activity in HepG2 cells. In China, many people drink jujuba tea and believe in the synergic effects of jujuba and tea for better health. We therefore investigated the effects of CHCl 3- F and green tea extract (GTE), and their underlying mechanisms of action in HepG2 cells. Our results showed that GTE enhanced the effect of CHCl 3- F on cell viability in HepG2 cells, without cytotoxicity in rat hepatocytes, which was used as a normal cell model. Furthermore, combination of CHCl 3- F and GTE caused an effect on G1 phase arrest but not on apoptosis. Interestingly, the mechanism of the G1 arrest was associated, not with an increase in p27Kip1 levels and the hypohosphorylation of Rb , which are pathways used by CHCl 3- F on G1 arrest in HepG2 cells, but with increases in p53 and p21Waf1/Cip1 levels, and a decrease in cyclin E levels. Collectively, our findings suggest that combination of CHCl 3- F and GTE produces an enhanced cell growth inhibition effect, and that the resultant G1 arrest was caused via a different mechanism as that of CHCl 3- F treatment alone.
Aldose Reductase Inhibitors fromViola hondoensisW. Becker et H Boss
Authors: Chung Ill-Min , Kim Min-Young , Park Won-Hwan , Moon Hyung-In
Published: August 2008

The isolation and characterization of rat lens aldose reductase inhibitors from the Viola hondoensis W. Becker et H Boss were conducted. The extracts and organic fractions from V. hondoensis were tested. The MeOH extract and EtOAc fraction were found to exhibit potent rat lens aldose reductase inhibition in vitro, their IC50being 1.2 and 0.6 μg/ml, respectively. One major isoflavonoid glycoside was isolated from the ethyl acetate soluble fraction of V. hondoensis. Kakkalide was found to be the potential rat lens aldose reductase inhibitor (IC50= 0.34 μg/ml), and may be useful for the prevention and/or treatment of diabetic complications.
INVERSE SPECTRAL PROBLEM FOR ATOM-LIKE MESONS
Authors: MATRASULOV D. U. , SOBIROV Z. A. , SABIROV K. K.
Published: August 2008

Inverse spectral problem for the Dirac equation with quark–antiquark potential is treated. For a class of potentials of the form Q(x) = q(x) E + (m + x)I, where q(x) = o(1) for x → +∞, [Formula: see text], E = I2 is multiplicative identity matrix, it is proved that q(x) in the Dirac equation can be uniquely recovered from the data {λj, sj}. Here λj are the eigenvalues of the Dirac equation and sj are the values yj(0) = (sj, 0) T , where yj(x) are the normalized eigenfunctions of the Dirac Hamiltonian, [Formula: see text]. An algorithm for finding q(x) from the known first few data, corresponding to -J ≤ j ≤ J assuming that the rest of the data are the same as for q0(x):= 0, m = 0 is proposed.
AN APPLICATION OF THE CASORATIAN TECHNIQUE TO THE 2D TODA LATTICE EQUATION
Authors: MA WEN-XIU
Published: August 2008

A general Casoratian formulation is proposed for the 2D Toda lattice equation, which involves two coupled eigenfunction systems. Various Casoratian type solutions are generated, through solving the resulting linear conditions and using a Bäcklund transformation.
THE HEAVY LUGGAGE METRIC
Authors: ABELLANAS MANUEL , HURTADO FERRAN , PALOP BELÉN
Published: August 2008

In this paper we consider a new time metric called the Heavy Luggage Metric. This metric models the behavior of a traveller in a city wishing to walk as little as possible, maybe carrying some very heavy luggage. A transportation network allows the traveller to move between any pair of stations at cost zero, while walking has a cost proportional to the length of the walked path. We propose efficient algorithms for computing the closest and farthest Voronoi Diagrams for a set of points with respect to this metric.
Karst and mining geohazards with particular reference to the Chalk outcrop, England
Authors: Edmonds C.N.
Published: August 2008

Naturally formed karst landforms and historical man-made underground cavities occur widely across the Chalk outcrop. Spatial analysis reveals the broad-scale pattern of occurrence and the influence of causal factors. The Chalk underlies many large towns and cities of southern and eastern England, and each year additional subsidence sinkholes and crown holes appear without warning, causing damage to the built environment. The situation puts residents at risk, raises concerns for local authorities and has financial implications for insurers. These subsidence problems are triggered mostly by the actions of man involving an escape of water or excessive loading at the surface. Similar subsidence behaviour is exhibited by other rock types in the UK and internationally, although detailed characteristics can vary. Field observations and intrusive investigations of chalk karst and man-made subsidence features show a variety of distinctive characteristics. Ground subsidence dimensions and geological setting often provide clues about the cause and nature of movement. Back-analysis of remedial ground stabilization provides data on the typical subsurface void space available within natural cavities. Using these results an interpretive ground model is proposed to explain how sinkholes of varying size occur upon the Chalk. This forms a basis for understanding the differences between the sizes of recently formed sinkholes and geologically old sinkholes. Assessment of recorded subsidence event dimensions and causes provides guidelines on the scale of karst and mining geohazards posed to sites underlain by chalk. These have implications for foundation construction advice and disposal of surface water drainage.
Sinkhole hazard case histories in karst terrains
Authors: Waltham T.
Published: August 2008

With few exceptions, the ground collapses that constitute the karst geohazard in engineering activity in limestone terrains are induced by human activity. Subsidence sinkholes, formed entirely within the soil profile, constitute the most widespread karst geohazard, but are largely induced by engineered works, either directly or accidentally. Water table decline (as a result of pumped abstraction or quarry de-watering) and uncontrolled surface drainage input are the two key factors that induce subsidence sinkholes, especially where both are involved. Collapse sinkholes, formed by failure of bedrock over a cavity, are rare in natural karst landscapes, but may be induced by excessive loading imposed on limestone that lies above an open cave; the risks associated with this geohazard should be eliminated by implementation of an appropriate site investigation that includes proof drilling. Case studies to demonstrate the karst geohazard concern: (1) homes damaged by new sinkholes around a de-watered limestone quarry in Pennsylvania; (2) problems with sinkholes for a railway across dolomite karst in South Africa; (3) collapse of ground in pseudokarst in Guatemala; (4) failure of a viaduct pier into an unseen cave in Florida; (5) estimation of potential sizes of collapse sinkholes along a pipeline route over gypsum karst in Turkey. As hazardous new sinkholes in karst are almost entirely induced by either uncontrolled drainage or excessive loading, they should be largely eliminated by appropriate engineering design and works. These need to be based on a proper understanding of karst ground conditions.
A GIS-based prediction method to evaluate subsidence-induced damage from coal mining beneath a reservoir, Kyushu, Japan
Authors: Esaki T. , Djamaluddin I. , Mitani Y.
Published: August 2008

The occurrence of subsidence caused by mining may be a complex process that causes damage to the environment. In the last century there was significant development in prediction methods for calculating surface subsidence. However, because mining may take place by multi-seam extraction, the use of current prediction methods to obtain the distribution of subsidence is a difficult and time-consuming task. Furthermore, it is impracticable to evaluate damage accurately by this method. In this paper, a new prediction method has been developed to calculate 3D subsidence by combining a stochastic model of ground movements and a geographical information system (GIS). All the subsidence calculations are implemented by a computational program, where the components of the GIS are used to fulfil the spatial–temporal analysis function. This subsidence prediction technique has been applied to calculate ground movements resulting from 21 years of coal mining under a reservoir in Japan. Details of movement were sequentially predicted and simulated in terms of years. Furthermore, subsidence-induced damage owing to progressive horizontal strain was assessed. These values conformed to the acceptable strains in reservoir dams, thus ensuring safety against tensile failure of the concrete and consequent flooding.
Reducing ground subsidence involving geological CO
2
storage during longwall mining operations
Authors: Kempka T. , Waschbüsch M. , Azzam R. , Fernández-Steeger T.M.
Published: August 2008

Underground mining causes costly subsidence damage world-wide. In the 1980s German mining research developed stowage techniques using mining wastes during longwall mining operations. These were applied successfully, but not continuously because of economic considerations at that time. A combined technique for subsidence reduction, mining waste disposal and CO
2
storage is being developed within the study presented. Oedometer tests conducted on pumpable mining waste suspensions with various moisture contents reveal useful compression characteristics making them suitable for stowing materials in excavated areas. Laboratory CO
2
adsorption experiments on these wastes show remarkable CO
2
sorption capacities in comparison with residual coal seams. The combination of CO
2
storage and subsequent stowage can lead to a cost-effective way of subsidence reduction determined by the growing prices of CO
2
emission certificates and restricting regulations with regard to CO
2
emissions.
Comparison of Bandwidths in the Inferior Colliculus and the Auditory Nerve. II: Measurement Using a Temporally Manipulated Stimulus
Authors: Mc Laughlin Myles , Chabwine Joelle Nsimire , van der Heijden Marcel , Joris Philip X.
Published: August 2008

To localize low-frequency sounds, humans rely on an interaural comparison of the temporally encoded sound waveform after peripheral filtering. This process can be compared with cross-correlation. For a broadband stimulus, after filtering, the correlation function has a damped oscillatory shape where the periodicity reflects the filter's center frequency and the damping reflects the bandwidth (BW). The physiological equivalent of the correlation function is the noise delay (ND) function, which is obtained from binaural cells by measuring response rate to broadband noise with varying interaural time delays (ITDs). For monaural neurons, delay functions are obtained by counting coincidences for varying delays across spike trains obtained to the same stimulus. Previously, we showed that BWs in monaural and binaural neurons were similar. However, earlier work showed that the damping of delay functions differs significantly between these two populations. Here, we address this paradox by looking at the role of sensitivity to changes in interaural correlation. We measured delay and correlation functions in the cat inferior colliculus (IC) and auditory nerve (AN). We find that, at a population level, AN and IC neurons with similar characteristic frequencies (CF) and BWs can have different responses to changes in correlation. Notably, binaural neurons often show compression, which is not found in the AN and which makes the shape of delay functions more invariant with CF at the level of the IC than at the AN. We conclude that binaural sensitivity is more dependent on correlation sensitivity than has hitherto been appreciated and that the mechanisms underlying correlation sensitivity should be addressed in future studies.
Urine Stimulation Activates BK Channels in Mouse Vomeronasal Neurons
Authors: Zhang Peng , Yang Chun , Delay Rona J.
Published: August 2008

Most odor responses in mouse vomeronasal neurons are mediated by the phospholipase C (PLC) pathway, activation of which elevates diacylglycerol (DAG). Lucas et al. showed that DAG activates transient receptor potential channels, subfamily C, member 2 (TRPC2), resulting in a depolarizing Ca2+ influx. DAG can be subsequently converted to arachidonic acid (AA) by a DAG lipase, the role of which remains largely unknown. In this study, we found that urine stimulation of vomeronasal neurons activated large-conductance Ca2+-activated K+ (BK) channels via AA production. Using isolated neurons, we demonstrated that repetitive applications of AA potentiated a K+ current that required a Ca2+ influx and was sensitive to specific BK blockers. Using immunocytochemistry, we found that BK channels are present in vomeronasal neurons with labeling on the soma and heavy labeling on the dendrite with a BK channel antibody. We examined the role of these BK channels in regulating neuronal firing when the neuron was activated by membrane depolarization or urine. Contrary to a recent report, our data suggest that BK channels contribute to adaptation of urine/odor responses because the inhibition of BK channels during urine stimulation promoted repetitive firing. These data strongly support the hypothesis that AA mediates an inhibitory pathway through BK channels, a possible mechanism for odor adaptation in vomeronasal neurons.
A Lightweight Buyer‐Seller Watermarking Protocol
Authors: Wu Yongdong , Pang Hweehua
Published: August 2008

The buyer‐seller watermarking protocol enables a seller to successfully identify a traitor from a pirated copy, while preventing the seller from framing an innocent buyer. Based on finite field theory and the homomorphic property of public key cryptosystems such as RSA, several buyer‐seller watermarking protocols (N. Memon and P. W. Wong (2001) and C.‐L. Lei et al. (2004)) have been proposed previously. However, those protocols require not only large computational power but also substantial network bandwidth. In this paper, we introduce a new buyer‐seller protocol that overcomes those weaknesses by managing the watermarks. Compared with the earlier protocols, ours is n times faster in terms of computation, where n is the number of watermark elements, while incurring only O(1/lN) times communication overhead given the finite field parameter lN. In addition, the quality of the watermarked image generated with our method is better, using the same watermark strength.
AMP-Activated Protein Kinase Signaling Results in Cytoplasmic Sequestration of p27
Authors: Short John D. , Houston Kevin D. , Dere Ruhee , Cai Sheng-Li , Kim Jinhee , Johnson Charles L. , Broaddus Russell R. , Shen Jianjun , Miyamoto Susie , Tamanoi Fuyuhiko , Kwiatkowski David , Mills Gordon B. , Walker Cheryl Lyn
Published: August 2008

Tuberin, the Tsc2 gene product, integrates the phosphatidylinositol 3-kinase/mitogen-activated protein kinase (mitogenic) and LKB1/AMP-activated protein kinase (AMPK; energy) signaling pathways, and previous independent studies have shown that loss of tuberin is associated with elevated AMPK signaling and altered p27 function. In Tsc2-null tumors and tumor-derived cells from Eker rats, we observed elevated AMPK signaling and concordant cytoplasmic mislocalization of p27. Cytoplasmic localization of p27 in Tsc2-null cells was reversible pharmacologically using inhibitors of the LKB1/AMPK pathway, and localization of p27 to the cytoplasm could be induced directly by activating AMPK physiologically (glucose deprivation) or genetically (constitutively active AMPK) in Tsc2-proficient cells. Furthermore, AMPK phosphorylated p27 in vitro on at least three sites including T170 near the nuclear localization signal, and T170 was shown to determine p27 localization in response to AMPK signaling. p27 functions in the nucleus to suppress cyclin-dependent kinase-2 (Cdk2) activity and has been reported to mediate an antiapoptotic function when localized to the cytoplasm. We found that cells with elevated AMPK signaling and cytoplasmic p27 localization exhibited elevated Cdk2 activity, which could be suppressed by inhibiting AMPK signaling. In addition, cells with elevated AMPK signaling and cytoplasmic p27 localization were resistant to apoptosis, which could be overcome by inhibition of AMPK signaling and relocalization of p27 to the nucleus. These data show that AMPK signaling determines the subcellular localization of p27, and identifies loss of integration of pathways controlling energy balance, the cell cycle, and apoptosis due to aberrant AMPK and p27 function as a feature of cells that have lost the Tsc2 tumor suppressor gene. [Cancer Res 2008;68(16):6496–506]
Octamer 4 Small Interfering RNA Results in Cancer Stem Cell–Like Cell Apoptosis
Authors: Hu Tingsong , Liu Shanrong , Breiter Deborah R. , Wang Fang , Tang Ying , Sun Shuhan
Published: August 2008

Octamer 4 (Oct4), a member of the POU family of transcription factors, plays a key role in the maintenance of pluripotency and proliferation potential of embryonic stem cells. Cancer stem cell–like cells (CSCLC) are reported to be a minor population in tumors or even in tumor cell lines which also express Oct4. The role of Oct4 in CSCLCs still remains to be defined. In our study, we show that, in vitro, almost all murine Lewis lung carcinoma 3LL cells and human breast cancer MCF7 cells express Oct4 at high levels. This expression of Oct4 is successfully reduced by small interfering RNA, which eventually results in cell apoptosis. The signal pathway Oct4/Tcl1/Akt1 has been observed to be involved in this event. The repression of Oct4 reduces Tcl1 expression and further down-regulates the level of p-Ser.473-Akt1. In vivo, only ∼5% of tumor cells were detected to express Oct4 in established 3LL and MCF7 tumor models, respectively. Small interfering RNA against Oct4 successfully decreases the CSCLCs and markedly inhibits tumor growth. In summary, we show that Oct4 might maintain the survival of CSCLCs partly through Oct4/Tcl1/Akt1 by inhibiting apoptosis, which strongly indicates that targeting Oct4 may have important clinical applications in cancer therapy. [Cancer Res 2008;68(16):6533–40]
Inhibition of the Sodium/Potassium ATPase Impairs N-Glycan Expression and Function
Authors: Zavareh Reza Beheshti , Lau Ken S. , Hurren Rose , Datti Alessandro , Ashline David J. , Gronda Marcela , Cheung Pam , Simpson Craig D. , Liu Wei , Wasylishen Amanda R. , Boutros Paul C. , Shi Hui , Vengopal Amudha , Jurisica Igor , Penn Linda Z. , Reinhold Vern N. , Ezzat Shereen , Wrana Jeff , Rose David R. , Schachter Harry , Dennis James W. , Schimmer Aaron D.
Published: August 2008

Aberrant N-linked glycans promote the malignant potential of cells by enhancing the epithelial-to-mesenchymal transition and the invasive phenotype. To identify small molecule inhibitors of N-glycan biosynthesis, we developed a chemical screen based on the ability of the tetravalent plant lectin L-phytohemagglutinin (L-PHA) to bind and crosslink surface glycoproteins with β1,6GlcNAc-branched complex type N-glycans and thereby induce agglutination and cell death. In this screen, Jurkat cells were treated with a library of off-patent chemicals (n = 1,280) to identify molecules that blocked L-PHA–induced death. The most potent hit from this screen was the cardiac glycoside (CG) dihydroouabain. In secondary assays, a panel of CGs was tested for their effects on L-PHA–induced agglutination and cell death. All of the CGs tested inhibited L-PHA–induced death in Jurkat cells, and the most potent CG tested was digoxin with an EC50 of 60 ± 20 nmol/L. Digoxin also increased the fraction of some concanavalin A–binding N-glycans. Using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, digoxin specifically increased GlcNAc1Man3GlcNAc2Fuc1 and GlcNAc2Man3GlcNAc2Fuc1 oligosaccharides demonstrating an impairment of the N-glycan pathway. Consistent with this effect on the N-glycan pathway, digoxin inhibited N-glycosylation–mediated processes of tumor cell migration and invasion. Furthermore, digoxin prevented distant tumor formation in two mouse models of metastatic prostate cancer. Thus, taken together, our high throughput screen identified CGs as modifiers of the N-glycan pathway. These molecules can be used as tools to better understand the role of N-glycans in normal and malignant cells. Moreover, these results may partly explain the anticancer effect of CGs in cardiovascular patients. [Cancer Res 2008;68(16):6688–96]
Tumors Sound the Alarmin(s)
Authors: Coffelt Seth B. , Scandurro Aline B.
Published: August 2008

Recent evidence suggests that inflammatory molecules play critical roles in the development and progression of numerous tumors. However, one specific group of inflammatory molecules whose importance has been established in host immune responses, termed alarmins, has been largely overlooked in cancer biology. The function of several alarmins—including the defensins, LL-37, and HMGB1—in tumor development, progression, or suppression is discussed here. Taken together, these studies indicate that alarmins represent potential new targets for manipulation in a variety of tumors. [Cancer Res 2008;68(16):6482–5]
Variants in the ATM Gene Associated with a Reduced Risk of Contralateral Breast Cancer
Authors: Concannon Patrick , Haile Robert W. , Børresen-Dale Anne-Lise , Rosenstein Barry S. , Gatti Richard A. , Teraoka Sharon N. , Diep Anh T. , Jansen Laila , Atencio David P. , Langholz Bryan , Capanu Marinela , Liang Xiaolin , Begg Colin B. , Thomas Duncan C. , Bernstein Leslie , Olsen Jørgen H. , Malone Kathleen E. , Lynch Charles F. , Anton-Culver Hoda , Bernstein Jonine L. ,   for the Women's Environment, Cancer, and Radiation Epidemiology Study Collaborative Group
Published: August 2008

Between 5% and 10% of women who survive a first primary breast cancer will subsequently develop a second primary cancer in the contralateral breast. The Women's Environment, Cancer, and Radiation Epidemiology Study was designed to identify genetic and environmental determinants of contralateral breast cancer (CBC). In this study, 708 women with asynchronous CBC served as cases and 1,397 women with unilateral breast cancer served as controls. ATM, a serine-threonine kinase, controls the cellular response to DNA double-strand breaks, and has been implicated in breast cancer risk. Complete mutation screening of the ATM gene in all 2,105 study participants identified 240 distinct sequence variants; only 15 were observed in >1% of subjects. Among the rare variants, deleterious alleles resulting in loss of ATM function were associated with a nonsignificant increase in risk of CBC. In contrast, carriers of common variants had a statistically significant reduction in risk of CBC. Four of these 15 variants were individually associated with a significantly decreased risk of second primary breast cancer [c.1899-55T>G, rate ratio (RR), 0.5; 95% confidence interval (CI), 0.3–0.8; c.3161C>G, RR, 0.5; 95% CI, 0.3–0.9; c.5558A>T, RR, 0.2; 95% CI, 0.1–0.6; c.6348-54T>C RR, 0.2; 95% CI, 0.1–0.8]. These data suggest that some alleles of ATM may exert an antineoplastic effect, perhaps by altering the activity of ATM as an initiator of DNA damage responses or a regulator of p53. [Cancer Res 2008;68(16):6486–91]
Peptide Aptamers Targeting Mutant p53 Induce Apoptosis in Tumor Cells
Authors: Guida Elisa , Bisso Andrea , Fenollar-Ferrer Cristina , Napoli Marco , Anselmi Claudio , Girardini Javier E. , Carloni Paolo , Del Sal Giannino
Published: August 2008

Mutations in the p53 tumor suppressor gene frequently result in expression of p53 point mutants that accumulate in cancer cells and actively collaborate with tumor progression through the acquisition of novel properties. Interfering with mutant p53 functions may represent a valid alternative for blocking tumor growth and development of aggressive phenotypes. The interactions and activities of selected proteins can be specifically modulated by the binding of peptide aptamers (PA). In the present work, we isolated PAs able to interact more efficiently with p53 conformational mutants compared with wild-type p53. The interaction between mutant p53 and PAs was further characterized using molecular modeling. Transient expression of PAs was able to reduce the transactivation activity of mutant p53 and to induce apoptosis specifically in cells expressing mutant p53. These PAs could provide a potential strategy to inhibit the oncogenic functions of mutant p53 and improve mutant p53-targeted cancer therapies. [Cancer Res 2008;68(16):6550–8]
Role of hMOF-Dependent Histone H4 Lysine 16 Acetylation in the Maintenance of TMS1/ASC Gene Activity
Authors: Kapoor-Vazirani Priya , Kagey Jacob D. , Powell Doris R. , Vertino Paula M.
Published: August 2008

Epigenetic silencing of tumor suppressor genes in human cancers is associated with aberrant methylation of promoter region CpG islands and local alterations in histone modifications. However, the mechanisms that drive these events remain unclear. Here, we establish an important role for histone H4 lysine 16 acetylation (H4K16Ac) and the histone acetyltransferase hMOF in the regulation of TMS1/ASC, a proapoptotic gene that undergoes epigenetic silencing in human cancers. In the unmethylated and active state, the TMS1 CpG island is spanned by positioned nucleosomes and marked by histone H3K4 methylation. H4K16Ac was uniquely localized to two sharp peaks that flanked the unmethylated CpG island and corresponded to strongly positioned nucleosomes. Aberrant methylation and silencing of TMS1 was accompanied by loss of the H4K16Ac peaks, loss of nucleosome positioning, hypomethylation of H3K4, and hypermethylation of H3K9. In addition, a single peak of histone H4 lysine 20 trimethylation was observed near the transcription start site. Down-regulation of hMOF or another component of the MSL complex resulted in a gene-specific decrease in H4K16Ac, loss of nucleosome positioning, and silencing of TMS1. Gene silencing induced by H4K16 deacetylation occurred independently of changes in histone methylation and DNA methylation and was reversed on hMOF reexpression. These results indicate that the selective marking of nucleosomes flanking the CpG island by hMOF is required to maintain TMS1 gene activity and suggest that the loss of H4K16Ac, mobilization of nucleosomes, and transcriptional down-regulation may be important events in the epigenetic silencing of certain tumor suppressor genes in cancer. [Cancer Res 2008;68(16):6810–21]
Cross-talk between LPA1 and Epidermal Growth Factor Receptors Mediates Up-regulation of Sphingosine Kinase 1 to Promote Gastric Cancer Cell Motility and Invasion
Authors: Shida Dai , Fang Xianjun , Kordula Tomasz , Takabe Kazuaki , Lépine Sandrine , Alvarez Sergio E. , Milstien Sheldon , Spiegel Sarah
Published: August 2008

Lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) are lysophospholipid mediators of diverse cellular processes important for cancer progression. S1P is produced by two sphingosine kinases, SphK1 and SphK2. Expression of SphK1 is elevated in many cancers. Here, we report that LPA markedly enhanced SphK1 mRNA and protein in gastric cancer MKN1 cells but had no effect on SphK2. LPA also up-regulated SphK1 expression in other human cancer cells that endogenously express the LPA1 receptor, such as DLD1 colon cancer cells and MDA-MB-231 breast cancer cells, but not in HT29 colon cancer cells or MDA-MB-453 breast cancer cells, which do not express the LPA1 receptor. An LPA1 receptor antagonist or down-regulation of its expression prevented SphK1 and S1P3 receptor up-regulation by LPA. LPA transactivated the epidermal growth factor receptor (EGFR) in these cells, and the EGFR inhibitor AG1478 attenuated the increased SphK1 and S1P3 expression induced by LPA. Moreover, down-regulation of SphK1 attenuated LPA-stimulated migration and invasion of MNK1 cells yet had no effect on expression of neovascularizing factors, such as interleukin (IL)-8, IL-6, urokinase-type plasminogen activator (uPA), or uPA receptor induced by LPA. Finally, down-regulation of S1P3, but not S1P1, also reduced LPA-stimulated migration and invasion of MKN1 cells. Collectively, our results suggest that SphK1 is a convergence point of multiple cell surface receptors for three different ligands, LPA, EGF, and S1P, which have all been implicated in regulation of motility and invasiveness of cancer cells. [Cancer Res 2008;68(16):6569–77]
Modulation of Protective T Cell Immunity by Complement Inhibitor Expression on Tumor Cells
Authors: Varela Juan C. , Imai Masaki , Atkinson Carl , Ohta Rieko , Rapisardo Michelle , Tomlinson Stephen
Published: August 2008

Complement-inhibitory proteins expressed on cancer cells can provide protection from antitumor antibodies and may potentially modulate the induction of an immune response to tumor-associated antigens. In the current study, we investigated the consequences of complement inhibitor down-regulation on the effector and inductive phases of an immune response. Stable small interfering RNA–mediated down-regulation of the complement inhibitor Crry on MB49 murine bladder cancer cells increased their susceptibility to monoclonal antibody and complement in vitro. In a syngeneic model of metastatic cancer, the down-regulation of Crry on i.v.-injected MB49 cells was associated with a significant decrease in tumor burden and an increase in the survival of challenged mice. However, monoclonal antibody therapy had no additional benefit. There was an antitumor IgG response, but the response was not effected by Crry down-regulation on inoculated tumor cells. Down-regulation of Crry on MB49 cells resulted in an enhanced antitumor T-cell response in challenged mice (measured by lymphocyte IFN-γ secretion), and CD8+ T cell depletion of mice prior to injection of MB49 cells completely abrogated the effect of Crry down-regulation on tumor burden and survival. Deficiency of C3 also abrogated the effect of Crry down-regulation on the survival of MB49-challenged mice, indicating a complement-dependent mechanism. These data indicate that complement inhibitors expressed on a tumor cell can suppress a T cell response and that enhancing complement activation on a tumor cell surface can promote protective T cell immunity. [Cancer Res 2008;68(16):6734–42]
Sp1-Mediated TRAIL Induction in Chemosensitization
Authors: Xu Jing , Zhou Jun-Ying , Wei Wei-Zen , Philipsen Sjaak , Wu Gen Sheng
Published: August 2008

The regulation of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) in cancer chemotherapy is not fully understood. Here, we show that the histone deacetylase (HDAC) inhibitors induce TRAIL in human breast cancer cells. Induction of TRAIL by the HDAC inhibitor MS275 can be enhanced by Adriamycin. Using different reporter constructs in conjunction with transcription activity assays and chromatin immunoprecipitation assays, we provide evidence that the transcription factor Sp1 is responsible for TRAIL induction by MS275 alone or in combination with Adriamycin. Further, we show that the combined treatment of breast cancer cells with MS275 and Adriamycin significantly increases apoptotic cell death via the activation of both death receptor and mitochondrial apoptotic pathways. Down-regulation of TRAIL by small interfering RNA silencing decreased MS275-mediated Adriamycin-induced caspase activation and apoptosis, thus conferring Adriamycin resistance. More importantly, breast cancer T47D cells in which Sp1 was knocked down or Sp1-knockout mouse embryonic stem cells were resistant to the combined treatments. Taken together, our results indicate that induction of TRAIL by the combined treatments with MS275 and Adriamycin is mediated by Sp1 and suggest that transcription factor Sp1 is an important target for the development of novel anticancer agents. [Cancer Res 2008;68(16):6718–26]
Stage-Specific Inhibitory Effects and Associated Mechanisms of Silibinin on Tumor Progression and Metastasis in Transgenic Adenocarcinoma of the Mouse Prostate Model
Authors: Raina Komal , Rajamanickam Subapriya , Singh Rana P. , Deep Gagan , Chittezhath Manesh , Agarwal Rajesh
Published: August 2008

Herein, using transgenic adenocarcinoma of the mouse prostate (TRAMP) model, we assessed the “stage-specific” efficacy of silibinin feeding against prostate cancer (PCa) initiation, progression, angiogenesis and metastasis, and associated molecular events involved in silibinin effects during these stages. Male TRAMP mice starting at ages 4, 12, 20, and 30 weeks of age were fed with control or 1% silibinin-supplemented diet for 8 to 15 weeks in stage-specific manners. At the end of studies, silibinin-fed mice showed less severe prostatic lesions compared with positive controls. During early stages of prostate tumor development, silibinin mediated its efficacy mostly via antiproliferative mechanisms. Feeding of silibinin to animals burdened with higher stages of prostate tumor significantly decreased tumor grade via antiproliferative effect, and inhibition of angiogenesis as evidenced by decreased expressions of platelet endothelial cell adhesion molecule-1/CD-31, vascular endothelial growth factor, and associated receptor, vascular endothelial growth factor R2, hypoxia-inducible factor-1α, and inducible nitric oxide synthase. Metastasis to distant organs was decreased in silibinin-fed mice, which was associated with a decreased expression of matrix metalloproteinases, mesenchymal markers snail-1, and fibronectin in the prostatic tissue and retention of epithelial characteristics. Together, these findings are both novel and highly significant in establishing the dual efficacy of silibinin where it inhibits progression of primary prostatic tumor and also shows protective efficacy against angiogenesis and late stage metastasis. These effects of silibinin could have potential implications to improve the morbidity and survival in PCa patients. [Cancer Res 2008;68(16):6822–30]
Aging and Cancer-Related Loss of Insulin-like Growth Factor 2 Imprinting in the Mouse and Human Prostate
Authors: Fu Vivian X. , Dobosy Joseph R. , Desotelle Joshua A. , Almassi Nima , Ewald Jonathan A. , Srinivasan Rajini , Berres Mark , Svaren John , Weindruch Richard , Jarrard David F.
Published: August 2008

Loss of imprinting (LOI) is an epigenetic alteration involving loss of parental origin-specific expression at normally imprinted genes. A LOI for Igf2, a paracrine growth factor, is important in cancer progression. Epigenetic modifications may be altered by environmental factors. However, is not known whether changes in imprinting occur with aging in prostate and other tissues susceptible to cancer development. We found a LOI for Igf2 occurs specifically in the mouse prostate associated with increased Igf2 expression during aging. In older animals, expression of the chromatin insulator protein CTCF and its binding to the Igf2-H19 imprint control region was reduced. Forced down-regulation of CTCF leads to Igf2 LOI. We further show that Igf2 LOI occurs with aging in histologically normal human prostate tissues and that this epigenetic alteration was more extensive in men with associated cancer. This finding may contribute to a postulated field of cancer susceptibility that occurs with aging. Moreover, Igf2 LOI may serve as a marker for the presence of prostate cancer. [Cancer Res 2008;68(16):6797–802]
Cardiac Memory in Patients With Wolff-Parkinson-White Syndrome
Authors: Ghosh Subham , Rhee Edward K. , Avari Jennifer N. , Woodard Pamela K. , Rudy Yoram
Published: August 2008

Background—

Cardiac memory refers to a change in ventricular repolarization induced by and persisting for minutes to months after cessation of a period of altered ventricular activation (eg, resulting from pacing or preexcitation in patients with Wolff-Parkinson-White syndrome). ECG imaging (ECGI) is a novel imaging modality for noninvasive electroanatomic mapping of epicardial activation and repolarization.

Methods and Results—

Fourteen pediatric patients with Wolff-Parkinson-White syndrome and no other congenital disease, were imaged with ECGI a day before and 45 minutes, 1 week, and 1 month after successful catheter ablation. ECGI determined that preexcitation sites were consistent with sites of successful ablation in all cases to within a 1-hour arc of each atrioventricular annulus. In the preexcited rhythm, activation-recovery interval (ARI) was the longest (349±6 ms) in the area of preexcitation leading to high average base-to-apex ARI dispersion of 95±9 ms (normal is ≈40 ms). The ARI dispersion remained the same 45 minutes after ablation, although the activation sequence was restored to normal. ARI dispersion was still high (79±9 ms) 1 week later and returned to normal (45±6 ms) 1 month after ablation.

Conclusions—

The study demonstrates that ECGI can noninvasively localize ventricular insertion sites of accessory pathways to guide ablation and evaluate its outcome in pediatric patients with Wolff-Parkinson-White syndrome. Wolff-Parkinson-White is associated with high ARI dispersion in the preexcited rhythm that persists after ablation and gradually returns to normal over a period of 1 month, demonstrating the presence of cardiac memory. The 1-month time course is consistent with transcriptional reprogramming and remodeling of ion channels.
Increased Risk of Stroke in Patients With Coronary Artery Disease and Sleep Apnea
Authors: Valham Fredrik , Mooe Thomas , Rabben Terje , Stenlund Hans , Wiklund Urban , Franklin Karl A.
Published: August 2008

Background—

The effect of sleep apnea on mortality and cardiovascular morbidity is mainly unknown. We aimed to study whether sleep apnea is related to stroke, death, or myocardial infarction in patients with symptomatic coronary artery disease.

Methods and Results—

A total of 392 men and women with coronary artery disease referred for coronary angiography were examined by use of overnight sleep apnea recordings. Sleep apnea, defined as an apnea-hypopnea index ≥5, was recorded in 54% of the patients. All patients were followed up prospectively for 10 years, and no one was lost to follow-up. Stroke occurred in 47 (12%) of 392 patients during follow-up. Sleep apnea was associated with an increased risk of stroke, with an adjusted hazard ratio of 2.89 (95% confidence interval 1.37 to 6.09,
P
=0.005), independent of age, body mass index, left ventricular function, diabetes mellitus, gender, intervention, hypertension, atrial fibrillation, a previous stroke or transient ischemic attack, and smoking. Patients with an apnea-hypopnea index of 5 to 15 and patients with an apnea-hypopnea index ≥15 had a 2.44 (95% confidence interval 1.08 to 5.52) and 3.56 (95% confidence interval 1.56 to 8.16) times increased risk of stroke, respectively, than patients without sleep apnea, independent of confounders (
P
for trend=0.011). Death and myocardial infarction were not related to sleep apnea. Intervention in the form of coronary artery bypass grafting or percutaneous coronary intervention was related to a longer survival but did not affect the incidence of stroke.

Conclusions—

Sleep apnea is significantly associated with the risk of stroke among patients with coronary artery disease who are being evaluated for coronary intervention.