bluuebunny/crossref_metadata_2025 huggingface dataset:
Diastolic calcium is elevated in metabolic recovery of cardiomyocytes expressing elevated levels of the Na+/H+exchanger
Authors: Baczkó István , Mraiche Fatima , Light Peter E. , Fliegel Larry
Published: December 2008

In the myocardium, the Na+/H+exchanger isoform 1 (NHE1) plays a pivotal role in mediating ischemia–reperfusion (I/R) injury by causing intracellular Na+accumulation that results in a subsequent increase in intracellular calcium (Ca2+overload). One of the major clinical correlates of I/R injury is contractile dysfunction, in which Ca2+overload via increased Na+/Ca2+exchange is a major contributor. To better understand the cellular role of NHE1 during I/R injury, contractile function and calcium transients were measured during metabolic inhibition and recovery in single ventricular myocytes from transgenic mice with elevated NHE1 expression. During normoxic conditions, no differences were seen between NHE1-overexpressing cardiomyocytes and wild-type (WT) cardiomyocytes with respect to fractional cell shortening (FCS), rate of shortening (+dL/dt), and rate of relaxation (–dL/dt). When metabolic recovery followed metabolic inhibition, NHE1-overexpressing ventricular myocytes exhibited a significant increase in FCS (130.2% ± 11.77% baseline) and ±dL/dt (146.93% ± 12.27% baseline). This correlated with a significant increase in the concentration of diastolic intracellular calcium, which was attenuated by the NHE1 inhibitor HOE694. These results indicate that in normoxic conditions, elevated NHE1 expression does not alter contractile function. During metabolic recovery, however, elevated NHE1 expression increased diastolic Ca2+loading that led to augmented cell contractility.
Myocardial protection with enalaprilat in patients unresponsive to ischemic preconditioning during percutaneous coronary intervention
Authors: Ungi Imre , Pálinkás Attila , Nemes Attila , Ungi Tamás , Thury Attila , Sepp Róbert , Horváth Tamás , Forster Tamás , Végh Ágnes
Published: December 2008

Cardioprotection due to angiotensin enzyme inhibitors is attributed, at least in part, to the inhibition of bradykinin breakdown and the preconditioning effect of the elevated endogenous bradykinin level. We have previously shown that in patients undergoing percutaneous coronary intervention, one 120-second balloon inflation is insufficient to precondition the heart. The objective of the present study was to examine whether the administration of enalaprilat to these patients results in protection. Twenty patients underwent two 120-second coronary artery occlusions separated by a reperfusion interval of 10 min. Ten patients were given 50 µg·min–1 enalaprilat in an intracoronary infusion between the balloon inflations, whereas the others received an infusion of saline. In the latter control patients, there were no significant differences in ST-segment elevation between the consecutive occlusions (peak ST: 1.61 ± 0.17 vs. 1.61 ± 0.16 mV; time to reach 0.5 mV ST elevation: 16 ± 4 vs. 22 ± 7 s; mean ST: 1.03 ± 0.12 vs. 1.02 ± 0.11 mV). In the patients who received enalaprilat before the second balloon inflation, the ST-segment elevation was significantly less pronounced and slower during the second inflation than during the first (peak ST: 1.80 ± 0.18 vs. 1.41 ± 0.19 mV; time to reach 0.5 mV ST elevation: 18 ± 4 vs. 30 ± 4 s; mean ST: 1.04 ± 0.11 vs. 0.85 ± 0.14 mV). We conclude that enalaprilat administered during percutaneous coronary intervention provides protection to patients who do not have a protective response to the initial balloon inflation.
Predator diet and prey adaptive responses: Can tadpoles distinguish between predators feeding on congeneric vs. conspecific prey?
Authors: Ferland-Raymond Bastien , Murray Dennis L.
Published: December 2008

Predator diet can play an important role in facilitating detection of predation risk among prospective prey, and such detection should have adaptive significance in reducing mortality in environments where not all predators confer similar risk. In the laboratory, we tested behavioural and morphological responses of tadpoles from two congeneric frog species (bullfrog ( Rana catesbeiana Shaw, 1802) and mink frog ( Rana septentrionalis Baird, 1854)) to cues from an odonate predator (genus Aeshna Fabricius, 1775). In a separate experiment we found that both frog species had similar baseline vulnerability to Aeshna predation, implying that species’ responses to predators feeding on conspecific vs. congeneric prey also would be similar. Both species reduced their activity in the presence of predators feeding on tadpoles of either species vs. those fed invertebrates (Libellulidae) or not subjected to predators (controls). Bullfrog tadpoles grew bigger than controls when exposed to predators fed mink frog tadpoles only, whereas mink frogs failed to show a comparable response. Neither species exhibited changes in shape that were attributable to predator diet. Our results suggest that closely related frog species do not distinguish between predators feeding on conspecific vs. congeneric prey, implying that selection favours generalized antipredator responses when prey species are subject to similar predation risk.
Demography of the lizard Sceloporus grammicus: exploring temporal variation in population dynamics
Authors: Zúñiga-Vega J. J. , Méndez-de la Cruz F. R. , Cuellar O.
Published: December 2008

We conducted a 5 year demographic study in one population of the viviparous lizard Sceloporus grammicus Wiegmann, 1828 in central México. The population was structured in three size classes (juveniles, small adults, and asymptotic adults) for which we estimated annual survival and fecundity rates. A population projection matrix was constructed for each annual transition. All of them resulted in finite rates of population growth (λ) that, although variable from year to year (from 0.808 to 1.065), were not significantly different than unity, indicating population stability. Elasticity analysis revealed that survival staying in the same size class was the demographic process that made the greatest contribution to λ values in most years. Similarly, the stasis of large adults was the vital rate with the highest relative importance for population persistence. To incorporate the observed yearly variation in long-term population projections, we used a mean matrix, a stochastic simulation, and a resampling procedure. All these resulted in long-term population growth rates that were not significantly different than unity. Our results indicate overall demographic stability for the studied population of S. grammicus.
Effect of cyclic and declining food supply on great grey owls in boreal Sweden
Authors: Hipkiss T. , Stefansson O. , Hörnfeldt B.
Published: December 2008

In this study of 35 years of data, we examine the short-term (cyclic) and long-term relationship between breeding success of great grey owls ( Strix nebulosa Forster, 1772) and their food supply (bank voles ( Clethrionomys glareolus (Schreber, 1780)), grey-sided voles ( Clethrionomys rufocanus (Sundevall, 1846)), and field voles ( Microtus agrestis (L., 1761))) in northern Sweden. Annual number of owl nests showed a 3 year cyclicity, which as predicted, corresponded to the length of the vole cycle in the region. Mean annual brood size also fluctuated and was positively dependent on the vole supply during the same spring. In this region, there has also been a decline in vole numbers in recent decades, from high-amplitude cycles in the 1970s to subsequent low-amplitude cycles. Correspondingly, and as predicted, mean annual brood size of the owls also declined, although only during the third years of the vole cycle when vole supply in spring and brood size of the owls is at its highest level in high-amplitude cycles. We predict that in the long run the vole decline, associated with increasingly milder winters, and the reduction of the brood size of the owls, especially in years of high owl breeding success, will have serious implications for the population of great grey owls in Scandinavia.
S-MOUNTAIN METHOD FOR OBTAINING FOCUS POINTS FROM DATA
Authors: YAGER RONALD R.
Published: December 2008

We introduce a variation of the Mountain Method called the S-Mountain Method, an algorithm for finding focus points from data points based on the similarity of a focus point with the data points. An important aspect of this algorithm is the association of energy levels with the data points and the reduction of these energy levels as we discover focus points. The rate of reduction of the energy level at a data point is related to its similarity with the recently discovered focus point. We provide a general form for this reduction operation using the t-norm operators. We show how this S-Mountain algorithm can be used to discover focus elements that are granular objects such as fuzzy subsets. Finally we extend the S-Mountain method to environments where our similarities are drawn from an ordinal scale. Here we discuss the interesting question of comparing objects consisting of collections of ordinal values.
The future of geological modelling in hydrocarbon development: introduction
Authors: Robinson Adam
Published: December 2008

The 3D geological model is still regarded as one of the newest and most innovative tools for reservoir management purposes. The computer modelling of structures, rock properties and fluid flow in hydrocarbon reservoirs has evolved from a specialist activity to part of the standard desktop toolkit and the application of these techniques has allowed all disciplines of the subsurface team to collaborate in a common workspace. The papers in this volume result from a two-day conference at the Geological Society that brought together modelling software practitioners from the geoscience community. The papers presented here provide an excellent illustration from across the industry and academia of where we are and give some interesting pointers to where we are heading. The authors and their parent companies and institutes are thanked for sharing this information.
Assessing structural controls on reservoir performance in different stratigraphic settings
Authors: Tveranger J. , Howell J. , Aanonsen S. I. , Kolbjørnsen O. , Semshaug S. L. , Skorstad A. , Ottesen S.
Published: December 2008

The present study attempts to qualify the impact of tectonic parameters on hydrocarbon production in reservoir models representing four clastic depositional environments. Eleven sectors from existing 3D reservoir models, representing fluvial, tidal, shallow marine and deep marine depositional settings, were re-sampled into a fixed-volume, unfaulted model grid. Each sample was permutated into 73 different faulted model configurations by using predefined combinations of fault patterns, maximum fault-throw, shale gouge ratio and shale smear factor. The resulting 803 models were run in a fluid flow simulator and results statistically analysed to identify changes in fluid flow response caused by changing model input parameters. Finally, outcomes for each of the four depositional environments were compared. Although an inadequate database and technical limitations with the input models restrict our ability to draw quantitative conclusions, a number of qualitative interpretations can be made. The four investigated stratigraphies respond differently to identical fault parameter settings. Thus, there is a clear link between the depositional model input and the impact that faults have on production parameters. This suggests that sedimentological factors have a significant influence on which and to what extent fault parameters affect petroleum production. Varying degrees of impact can be identified for each fault parameter in each of the four depositional model types. Within the limitation of this study, a qualitative assessment of these is formulated.
Reservoir-scale 3D sedimentary modelling: approaches to integrate sedimentology into a reservoir characterization workflow
Authors: Labourdette Richard , Hegre Joann , Imbert Patrice , Insalaco Enzo
Published: December 2008

Reservoir production is highly dependent on reservoir models. A key problem faced in the development of a hydrocarbon reservoir is that of constructing a reservoir model that can generate reliable production forecasts under various development scenarios. Therefore, geological models have to be built in three dimensions (3D). Unfortunately, manual construction of 3D geological models (deterministically) is almost impossible, which explains why geologists often limit their interpretation to two dimensional (2D) correlation panels, fence-diagrams or maps. Consequently, geological conceptual models are rarely included or considerably simplified in reservoir models used for flow simulations and replaced by stochastic or geostatistic approaches. In spite of this admission of failure, sedimentological cross-sections and maps contain most of the knowledge and concepts of sedimentologists. They represent the outcome of sedimentological studies, including available well data, seismic interpretation and especially sedimentological and environmental concepts, incorporating all facies transitions and successions in a high-resolution stratigraphic framework. They allow fine temporal- and spatial-scale sedimentological heterogeneities to be identified. The integration of these fine-scale sedimentological heterogeneities is an essential step in improving the precision and accuracy of static reservoir models and volumetric calculations. This paper demonstrates the quantitative influence of introducing sedimentological information into the reservoir characterization workflow using a simple deterministic workflow. The described incorporation of sedimentological knowledge through facies 3D proportions cubes allows a direct assessment to facies distribution multi-realization scheme and associated uncertainties by applying stochastic simulations.
IL-6–Induced Stimulation of c-Myc Translation in Multiple Myeloma Cells Is Mediated by Myc Internal Ribosome Entry Site Function and the RNA-Binding Protein, hnRNP A1
Authors: Shi Yijiang , Frost Patrick J. , Hoang Bao Q. , Benavides Angelica , Sharma Sanjai , Gera Joseph F. , Lichtenstein Alan K.
Published: December 2008

Prior work indicates that c-myc translation is up-regulated in multiple myeloma cells. To test a role for interleukin (IL)-6 in myc translation, we studied the IL-6–responsive ANBL-6 and IL-6–autocrine U266 cell lines as well as primary patient samples. IL-6 increased c-myc translation, which was resistant to rapamycin, indicating a mechanism independent of mammalian target of rapamycin (mTOR) and cap-dependent translation. In contrast, the cytokine enhanced cap-independent translation via a stimulatory effect on the myc internal ribosome entry site (IRES). As known IRES-trans–activating factors (ITAF) were unaffected by IL-6, we used a yeast-three-hybrid screen to identify novel ITAFs and identified hnRNP A1 (A1) as a mediator of the IL-6 effect. A1 specifically interacted with the myc IRES in filter binding assays as well as EMSAs. Treatment of myeloma cells with IL-6 induced serine phosphorylation of A1 and increased its binding to the myc IRES in vivo in myeloma cells. Primary patient samples also showed binding between A1 and the IRES. RNA interference to knock down hnRNP A1 prevented an IL-6 increase in myc protein expression, myc IRES activity, and cell growth. These data point to hnRNP A1 as a critical regulator of c-myc translation and a potential therapeutic target in multiple myeloma. [Cancer Res 2008;68(24):10215–22]
Phospholipase Cγ1 Is Required for Metastasis Development and Progression
Authors: Sala Gianluca , Dituri Francesco , Raimondi Claudio , Previdi Sara , Maffucci Tania , Mazzoletti Marco , Rossi Cosmo , Iezzi Manuela , Lattanzio Rossano , Piantelli Mauro , Iacobelli Stefano , Broggini Massimo , Falasca Marco
Published: December 2008

Cell motility and invasion play an essential role in the development of metastasis. Evidence suggests that the enzyme phospholipase Cγ1 (PLCγ1) may be involved in tumor progression and possibly development of metastasis. In this study, we show that down-regulation of PLCγ1 expression severely impairs activation of the small GTP-binding protein Rac and cell invasion in breast cancer cell lines and U87 in vitro. Experimental metastasis assays in nude mice show that inducible knockdown of PLCγ1 strongly inhibits development of MDA-MB-231–derived lung metastasis and reverts metastasis formation. In addition, analysis of 60 breast cancer patients' tissues revealed an increase of PLCγ1 expression in metastasis compared with the primary tumor in 50% of tissues analyzed. These data show a critical role of PLCγ1 in the metastatic potential of cancer cells, and they further indicate that PLCγ1 inhibition has a therapeutic potential in the treatment of metastasis dissemination. [Cancer Res 2008;68(24):10187–96]
p53-Responsive MicroRNAs 192 and 215 Are Capable of Inducing Cell Cycle Arrest
Authors: Braun Christian J. , Zhang Xin , Savelyeva Irina , Wolff Sonja , Moll Ute M. , Schepeler Troels , Ørntoft Torben F. , Andersen Claus L. , Dobbelstein Matthias
Published: December 2008

microRNAs provide a novel layer of regulation for gene expression by interfering with the stability and/or translation of specific target mRNAs. Overall levels of microRNAs are frequently down-regulated in cancer cells, and reducing general microRNA processing increases cancerogenesis in transgenic models, suggesting that at least some microRNAs might act as effectors in tumor suppression. Accordingly, the tumor suppressor p53 up-regulates miR-34a, a microRNA that contributes to apoptosis and acute senescence. Here, we used array hybridization to find that p53 induces two additional, mutually related clusters of microRNAs, leading to the up-regulation of miR-192, miR-194, and miR-215. The same microRNAs were detected at high levels in normal colon tissue but were severely reduced in many colon cancer samples. On the other hand, miR-192 and its cousin miR-215 can each contribute to enhanced CDKN1A/p21 levels, colony suppression, cell cycle arrest, and cell detachment from a solid support. These effects were partially dependent on the presence of wild-type p53. Antagonizing endogenous miR-192 attenuated 5-fluorouracil–induced accumulation of p21. Hence, miR-192 and miR-215 can act as effectors as well as regulators of p53; they seem to suppress cancerogenesis through p21 accumulation and cell cycle arrest. [Cancer Res 2008;68(24):10094–104]
p53 Small-Molecule Inhibitor Enhances Temozolomide Cytotoxic Activity against Intracranial Glioblastoma Xenografts
Authors: Dinca Eduard B. , Lu Kan V. , Sarkaria Jann N. , Pieper Russell O. , Prados Michael D. , Haas-Kogan Daphne A. , VandenBerg Scott R. , Berger Mitchel S. , James C. David
Published: December 2008

In this study, we investigated the precursor and active forms of a p53 small-molecule inhibitor for their effects on temozolomide (TMZ) antitumor activity against glioblastoma (GBM), using both in vitro and in vivo experimental approaches. Results from in vitro cell viability analysis showed that the cytotoxic activity of TMZ was substantially increased when p53 wild-type (p53wt) GBMs were cotreated with the active form of p53 inhibitor, and this heightened cytotoxic response was accompanied by increased poly(ADP-ribose) polymerase cleavage as well as elevated cellular phospho-H2AX. Analysis of the same series of GBMs, as intracranial xenografts in athymic mice, and administering corresponding p53 inhibitor precursor, which is converted to the active compound in vivo, yielded results consistent with the in vitro analyses: TMZ + p53 inhibitor precursor cotreatment of three distinct p53wt GBM xenografts resulted in significant enhancement of TMZ antitumor effect relative to treatment with TMZ alone, as indicated by serial bioluminescence monitoring as well as survival analysis (P < 0.001 for cotreatment survival benefit in each case). Mice receiving intracranial injection with p53null GBM showed similar survival benefit from TMZ treatment regardless of the presence or absence of p53 inhibitor precursor. In total, our results indicate that the p53 active and precursor inhibitor pair enhances TMZ cytotoxicity in vitro and in vivo, respectively, and do so in a p53-dependent manner. [Cancer Res 2008;68(24):10034–8]
Interaction between Single Nucleotide Polymorphisms in Selenoprotein P and Mitochondrial Superoxide Dismutase Determines Prostate Cancer Risk
Authors: Cooper Matthew L. , Adami Hans-Olov , Grönberg Henrik , Wiklund Fredrik , Green Fiona R. , Rayman Margaret P.
Published: December 2008

Selenium may affect prostate cancer risk via its plasma carrier selenoprotein P which shows dramatically reduced expression in prostate cancer tumors and cell lines. The selenoprotein P (SEPP1) Ala234 single nucleotide polymorphism (SNP) allele is associated with lower plasma selenoprotein P in men, reducing the concentration/activity of other antioxidant selenoproteins. Selenium status also modifies the effect of the mitochondrial superoxide dismutase (SOD2) SNP Ala16Val on prostate cancer risk. We investigated the relationship of these SNPs with prostate cancer risk. DNA from 2,975 cases and 1,896 age-matched controls from the population-based Prostate Cancer in Sweden study were genotyped using TaqMan assays. Cases were designated aggressive or nonaggressive prostate cancers at diagnosis by clinical criteria. Association with prostate cancer was investigated by logistic regression; gene-gene interaction using a general linear model. The mean plasma selenium concentration measured in 169 controls was relatively low (76.0 ± 17.2 μg/L). SNP genotype distributions were in Hardy-Weinberg equilibrium. SOD2-Ala16+ men were at a greater risk of prostate cancer [odds ratios (OR), 1.19; 95% confidence intervals (CI), 1.03–1.37] compared with SOD2-Val16 homozygotes. Men homozygous for SEPP1-Ala234 who were also SOD2-Ala16+ had a higher risk of prostate cancer (OR, 1.43; 95% CI, 1.17–1.76) and aggressive prostate cancer (OR, 1.60; 95% CI, 1.22–2.09) than those who were SOD2-Val16 homozygotes (interaction, prostate cancer P = 0.05; aggressive prostate cancer P = 0.01). This interaction was stronger in ever-smokers: SOD2-Ala16+ men homozygous for SEPP1-Ala234 had an almost doubled risk of prostate cancer (OR, 1.97; 95% CI, 1.33–2.91; interaction P = 0.001). In a low-selenium population, SOD2-Ala16+ men homozygous for SEPP1-Ala234 are at an increased risk of prostate cancer/aggressive prostate cancer especially if ever-smokers, because they are likely to produce more mitochondrial H2O2 that they cannot remove, thereby promoting prostate tumor cell proliferation and migration. [Cancer Res 2008;68(24):10171–7]
MicroRNA Microarray Identifies Let-7i as a Novel Biomarker and Therapeutic Target in Human Epithelial Ovarian Cancer
Authors: Yang Nuo , Kaur Sippy , Volinia Stefano , Greshock Joel , Lassus Heini , Hasegawa Kosei , Liang Shun , Leminen Arto , Deng Shan , Smith Lori , Johnstone Cameron N. , Chen Xian-Ming , Liu Chang-Gong , Huang Qihong , Katsaros Dionyssios , Calin George Adrian , Weber Barbara L. , Bützow Ralf , Croce Carlo M. , Coukos George , Zhang Lin
Published: December 2008

MicroRNAs (miRNA) are approximately 22-nucleotide noncoding RNAs that negatively regulate protein-coding gene expression in a sequence-specific manner via translational inhibition or mRNA degradation. Our recent studies showed that miRNAs exhibit genomic alterations at a high frequency and their expression is remarkably deregulated in ovarian cancer, strongly suggesting that miRNAs are involved in the initiation and progression of this disease. In the present study, we performed miRNA microarray to identify the miRNAs associated with chemotherapy response in ovarian cancer and found that let-7i expression was significantly reduced in chemotherapy-resistant patients (n = 69, P = 0.003). This result was further validated by stem-loop real-time reverse transcription-PCR (n = 62, P = 0.015). Both loss-of-function (by synthetic let-7i inhibitor) and gain-of-function (by retroviral overexpression of let-7i) studies showed that reduced let-7i expression significantly increased the resistance of ovarian and breast cancer cells to the chemotherapy drug, cis-platinum. Finally, using miRNA microarray, we found that decreased let-7i expression was significantly associated with the shorter progression-free survival of patients with late-stage ovarian cancer (n = 72, P = 0.042). This finding was further validated in the same sample set by stem-loop real-time reverse transcription-PCR (n = 62, P = 0.001) and in an independent sample set by in situ hybridization (n = 53, P = 0.049). Taken together, our results strongly suggest that let-7i might be used as a therapeutic target to modulate platinum-based chemotherapy and as a biomarker to predict chemotherapy response and survival in patients with ovarian cancer. [Cancer Res 2008;68(24):10307–14]
Tissue Factor Regulation by Epidermal Growth Factor Receptor and Epithelial-to-Mesenchymal Transitions: Effect on Tumor Initiation and Angiogenesis
Authors: Milsom Chloe C. , Yu Joanne L. , Mackman Nigel , Micallef Johann , Anderson G. Mark , Guha Abhijit , Rak Janusz W.
Published: December 2008

ErbB oncogenes drive the progression of several human cancers. Our study shows that in human carcinoma (A431) and glioma (U373) cells, the oncogenic forms of epidermal growth factor receptor (EGFR; including EGFRvIII) trigger the up-regulation of tissue factor (TF), the transmembrane protein responsible for initiating blood coagulation and signaling through interaction with coagulation factor VIIa. We show that A431 cancer cells in culture exhibit a uniform TF expression profile; however, these same cells in vivo exhibit a heterogeneous TF expression and show signs of E-cadherin inactivation, which is coupled with multilineage (epithelial and mesenchymal) differentiation. Blockade of E-cadherin in vitro, leads to the acquisition of spindle morphology and de novo expression of vimentin, features consistent with epithelial-to-mesenchymal transition. These changes were associated with an increase in EGFR-dependent TF expression, and with enhanced stimulation of vascular endothelial growth factor production, particularly following cancer cell treatment with coagulation factor VIIa. In vivo, cells undergoing epithelial-to-mesenchymal transition exhibited an increased metastatic potential. Furthermore, injections of the TF-blocking antibody (CNTO 859) delayed the initiation of A431 tumors in immunodeficient mice, and reduced tumor growth, vascularization, and vascular endothelial growth factor expression. Collectively, our data suggest that TF is regulated by both oncogenic and differentiation pathways, and that it functions in tumor initiation, tumor growth, angiogenesis, and metastasis. Thus, TF could serve as a therapeutic target in EGFR-dependent malignancies. [Cancer Res 2008;68(24):10068–76]
Chromosomal Rearrangements Leading to MLL Gene Fusions: Clinical and Biological Aspects
Authors: Harper David P. , Aplan Peter D.
Published: December 2008

Rearrangements of the MLL gene located at 11q23 are common chromosomal abnormalities associated with acute leukemia, especially infant and therapy-related leukemias. A variety of chimeric oncoproteins resulting from these rearrangements has been described; all of these include the NH2-terminal region of MLL implicated in protein-protein interactions and transcriptional repression. Although the molecular basis for the oncogenic activity of MLL chimeric proteins is incompletely understood, it seems to be derived, at least in part, through activation of clustered homeobox (HOX) genes. Here, we survey MLL gene rearrangements that are associated with acute leukemia and discuss molecular pathways leading to these rearrangements. [Cancer Res 2008;68(24):10024–7]
Drug Resistance Caused by Reversion Mutation
Authors: Ashworth Alan
Published: December 2008

Cells carrying mutated BRCA1 or BRCA2 genes are defective in DNA repair by homologous recombination and, as a consequence, are highly sensitive to inhibitors of poly (ADP-ribose) polymerase (PARP). This provides the basis for a novel “synthetic lethal” approach to cancer therapy. We have recently shown that this sensitivity can be reversed, and resistance to PARP inhibition can be acquired by deletion of a mutation in BRCA2. Furthermore, a similar mechanism seems to be associated with carboplatin resistance in some BRCA2 mutation carriers with ovarian cancer. [Cancer Res 2008;68(24):10021–3]
Premature Cell Cycle Entry Induced by Hepatitis B Virus Regulatory HBx Protein during Compensatory Liver Regeneration
Authors: Hodgson Amanda J. , Keasler Victor V. , Slagle Betty L.
Published: December 2008

The cycles of cell death and compensatory regeneration that occur during chronic hepatitis B virus (HBV) infection are central to viral pathogenesis and are a risk factor for the development of liver cancer. The HBV genome encodes one regulatory protein, HBx, which is required for virus replication, although its precise role in replication and pathogenesis is unclear. Because HBx can induce the G0-G1 transition in cultured cells, the purpose of this study was to examine the effect of HBx during liver regeneration. Transgenic mice expressing HBx (ATX) and their wild-type (WT) littermates were used in the partial hepatectomy (PH) model for compensatory regeneration. Liver tissues collected from ATX and WT mice at varying sacrifice time points after PH were examined for markers of cell cycle progression. When compared with WT liver tissues, ATX livers had evidence of premature cell cycle entry as assessed by several variables (BrdUrd incorporation, proliferating cell nuclear antigen and mitotic indices, and reduced steady-state p21 protein levels). However, HBx did not affect apoptosis, glycogen storage, or PH-induced steatosis. Together, these results show that HBx expression can induce cell cycle progression within the regenerating liver. Our data are consistent with a model in which HBx expression contributes to liver disease and cancer formation by affecting early steps in liver regeneration. [Cancer Res 2008;68(24):10341–8]
CXCR6 Induces Prostate Cancer Progression by the AKT/Mammalian Target of Rapamycin Signaling Pathway
Authors: Wang Jianhua , Lu Yi , Wang Jingchen , Koch Alisa E. , Zhang Jian , Taichman Russell S.
Published: December 2008

Previous studies show that the chemokine CXCL16 and its receptor CXCR6 are likely to contribute to prostate cancer (PCa). In this investigation, the role of the CXCR6 receptor in PCa was further explored. CXCR6 protein expression was examined using high-density tissue microarrays and immunohistochemistry. Expression of CXCR6 showed strong epithelial staining that correlated with Gleason score. In vitro and in vivo studies in PCa cell lines suggested that alterations in CXCR6 expression were associated with invasive activities and tumor growth. In addition, CXCR6 expression was able to regulate expression of the proangiogenic factors interleukin (IL)-8 or vascular endothelial growth factor (VEGF), which are likely to participate in the regulation of tumor angiogenesis. Finally, we found that CXCL16 signaling induced the activation of Akt, p70S6K, and eukaryotic initiation factor 4E binding protein 1 included in mammalian target of rapamycin (mTOR) pathways, which are located downstream of Akt. Furthermore, rapamycin not only drastically inhibited CXCL16-induced PCa cell invasion and growth but reduced secretion of IL-8 or VEGF levels and inhibited expression of other CXCR6 targets including CD44 and matrix metalloproteinase 3 in PCa cells. Together, our data shows for the first time that the CXCR6/AKT/mTOR pathway plays a central role in the development of PCa. Blocking the CXCR6/AKT/mTOR signaling pathway may prove beneficial to prevent metastasis and provide a more effective therapeutic strategy for PCa. [Cancer Res 2008;68(24):10367–76]
Heparanase Augments Epidermal Growth Factor Receptor Phosphorylation: Correlation with Head and Neck Tumor Progression
Authors: Cohen-Kaplan Victoria , Doweck Ilana , Naroditsky Inna , Vlodavsky Israel , Ilan Neta
Published: December 2008

Heparanase is an endoglycosidase that specifically cleaves heparan sulfate side chains, a class of glycosaminoglycans abundantly present in the extracellular matrix and on the cell surface. Heparanase activity is strongly implicated in tumor metastasis attributed to remodeling of the subepithelial and subendothelial basement membranes, resulting in dissemination of metastatic cancer cells. Moreover, heparanase up-regulation was noted in an increasing number of primary human tumors, correlating with tumors larger in size, increased microvessel density, and reduced postoperative survival rate, implying that heparanase function is not limited to tumor metastasis. This notion is supported by recent findings revealing induction of signaling molecules (i.e., Akt, p38) and gene transcription [i.e., tissue factor, vascular endothelial growth factor (VEGF)] by enzymatically-inactive heparanase. Here, we provide evidence that active and inactive heparanase proteins enhance epidermal growth factor receptor (EGFR) phosphorylation. Enhanced EGFR phosphorylation was associated with increased cell migration, cell proliferation, and colony formation, which were attenuated by Src inhibitors. Similarly, heparanase gene silencing by means of siRNA was associated with reduced Src and EGFR phosphorylation levels and decreased cell proliferation. Moreover, heparanase expression correlated with increased phospho-EGFR levels and progression of head and neck carcinoma, providing a strong clinical support for EGFR modulation by heparanase. Thus, heparanase seems to modulate two critical systems involved in tumor progression, namely VEGF expression and EGFR activation. Neutralizing heparanase enzymatic and nonenzymatic functions is therefore expected to profoundly affect tumor growth, angiogenesis, and metastasis. [Cancer Res 2008;68(24):10077–85
Mutational Inactivation of PTPRD in Glioblastoma Multiforme and Malignant Melanoma
Authors: Solomon David A. , Kim Jung-Sik , Cronin Julia C. , Sibenaller Zita , Ryken Timothy , Rosenberg Steven A. , Ressom Habtom , Jean Walter , Bigner Darell , Yan Hai , Samuels Yardena , Waldman Todd
Published: December 2008

An additional tumor suppressor gene on chromosome 9p telomeric to the CDKN2A/B locus has long been postulated to exist. Using Affymetrix 250K single nucleotide polymorphism arrays to screen for copy number changes in glioblastoma multiforme (GBM), we detected a high frequency of deletions of the PTPRD gene, which encodes a receptor protein tyrosine phosphatase at chromosome 9p23-24.1. Missense and nonsense mutations of PTPRD were identified in a subset of the samples lacking deletions, including an inherited mutation with somatic loss of the wild-type allele. We then sequenced the gene in melanoma and identified 10 somatic mutations in 7 of 57 tumors (12%). Reconstitution of PTPRD expression in GBM and melanoma cells harboring deletions or mutations led to growth suppression and apoptosis that was alleviated by both the somatic and constitutional mutations. These data implicate PTPRD in the pathogenesis of tumors of neuroectodermal origin and, when taken together with other recent reports of PTPRD mutations in adenocarcinoma of the colon and lung, suggest that PTPRD may be one of a select group of tumor suppressor genes that are inactivated in a wide range of common human tumor types. [Cancer Res 2008;68(24):10300–6]
Synergistic Antitumor Activity of Ixabepilone (BMS-247550) Plus Bevacizumab in Multiple In vivo Tumor Models
Authors: Lee Francis Y.F. , Covello Kelly L. , Castaneda Stephen , Hawken Donald R. , Kan David , Lewin Anne , Wen Mei-Li , Ryseck Rolf-Peter , Fairchild Craig R. , Fargnoli Joseph , Kramer Robert
Published: December 2008

Purpose: Angiogenesis is a critical step in the establishment, growth, and metastasis of solid tumors, and combination of antiangiogenic agents with chemotherapy is an attractive therapeutic option. We investigated the potential of ixabepilone, the first in a new class of antineoplastic agents known as epothilones, to synergize with antiangiogenic agents to inhibit tumor growth.

Experimental Design: In vitro and in vivo cytotoxicity of ixabepilone as single agent and in combination with two targeted antiangiogenic agents, bevacizumab or sunitinib, were examined in preclinical tumor models. Direct effects of the agents against endothelial cells was also examined and compared with the effects of paclitaxel as single agent and in combination with bevacizumab.

Results: Ixabepilone showed robust synergistic antitumor activity in combination with bevacizumab and sunitinib in preclinical in vivo models derived from breast, colon, lung, and kidney cancers. The synergistic antitumor effect was greater with ixabepilone compared with paclitaxel. Furthermore, ixabepilone was more effective than paclitaxel at killing endothelial cells expressing P-glycoprotein in vitro and inhibiting endothelial cell proliferation and tumor angiogenesis in vivo.

Conclusions: Ixabepilone may enhance the antitumor effects of antiangiogenic therapy by direct cytotoxicity and also indirectly via the killing of tumor-associated endothelial cells. Given that ixabepilone has reduced susceptibility to drug efflux pumps compared with taxanes, these data may explain the increased antiangiogenic and antitumor activity of ixabepilone in combination with antiangiogenic agents. Phase II studies to assess the efficacy and safety of ixabepilone plus bevacizumab in locally recurrent or metastatic breast cancer are planned.
Design of Folate-Linked Liposomal Doxorubicin to its Antitumor Effect in Mice
Authors: Yamada Atsushi , Taniguchi Yukimi , Kawano Kumi , Honda Takashi , Hattori Yoshiyuki , Maitani Yoshie
Published: December 2008

Purpose: Tumor cell targeting is a promising strategy for enhancing the therapeutic potential of chemotherapy agents. Polyethylene glycol (PEG)-coated (sterically stabilized) liposomes show enhanced accumulation on the surface of tumors, but steric hindrance by PEGylation reduces the association of the liposome-bound ligand with its receptor. To increase folate receptor (FR) targeting, we optimized the concentration and PEG spacer length of folate-PEG-lipid in liposomes.

Experimental Design: Three types of folate-linked liposomal doxorubicin were designed and prepared by optimizing the concentration and PEG spacer length of folate-PEG-lipid in PEGylated or non-PEGylated liposomes and by masking folate-linked liposomes where the folate ligand is “masked” by adjacent PEG spacers. The liposome targeting efficacy was evaluated in vitro and in vivo.

Results: In human oral carcinoma KB cells, which overexpress FR, modification with sufficiently long PEG spacer and a high concentration of folate ligand to non-PEGylated liposomes increased the FR-mediated association and cytotoxicity more than with PEGylated and masked folate-linked liposomes. On the contrary, in mice bearing murine lung carcinoma M109, modification with the folate ligand in PEGylated and masked folate-linked liposomes showed significantly higher antitumor effect than with non-PEGylated liposomes irrespective of the length of time in the circulation after intravenous injection.

Conclusions: The results of this study will be beneficial for the design and preparation of ligand-targeting carriers for cancer treatment.
Reduction of Human Melanoma Tumor Growth in Severe Combined Immunodeficient Mice by Passive Transfer of Antibodies Induced by a High Molecular Weight Melanoma-Associated Antigen Mimotope Vaccine
Authors: Wagner Stefan , Krepler Clemens , Allwardt Dorothee , Latzka Julia , Strommer Sabine , Scheiner Otto , Pehamberger Hubert , Wiedermann Ursula , Hafner Christine , Breiteneder Heimo
Published: December 2008

Purpose: The high molecular weight melanoma-associated antigen (HMW-MAA) is an attractive target for immunotherapy of malignant melanoma. We have recently generated a vaccine based on the HMW-MAA mimotope 225D9.2+ that was able to induce anti-HMW-MAA antibodies with antitumor activity in vitro. Here, we investigated the antitumor activity of these antibodies in a human melanoma xenotransplant severe combined immunodeficient (SCID) mouse model.

Experimental Design: Tumors were established by injecting the human melanoma 518A2 cells into C.B.17 SCID/SCID mice. In tumor prevention experiments, 200 μg purified total IgG antibodies were injected intravenously the same day or on day 5 in therapeutic experiments. Antibody administration was repeated every fourth day and tumor volumes were measured. Antibody specificity and tumor infiltration by macrophages were investigated by immunohistochemistry.

Results: Within 35 days after cell inoculation, antibody treatment reduced tumor growth up to 40% in the therapeutic and up to 62% in the tumor prevention experiments compared with the control mice. In tumors of all groups, a similar distribution of the HMW-MAA and no differences in infiltration of macrophages were detected by immunohistochemistry.

Conclusions: Here, we showed that antibodies induced by the 225D9.2+ mimotope effectively inhibited melanoma tumor growth. Additional mechanisms besides antibody-dependent cell cytotoxicity like disruption of interactions of melanoma cells mediated by extracellular matrix components seem to be involved in tumor growth inhibition. Based on our findings, we suggest that active immunization with this mimotope might be a promising strategy for treatment of melanoma.
Angiogenic Switch of Angiopietins-Tie2 System and Its Prognostic Value in Bladder Cancer
Authors: Szarvas Tibor , Jäger Tobias , Tötsch Martin , Vom Dorp Frank , Kempkensteffen Carsten , Kovalszky Ilona , Romics Imre , Ergün Süleyman , Rübben Herbert
Published: December 2008

Purpose: Vascular endothelial growth factor (VEGF), angiopoietins (Ang-1 and Ang-2), and their receptor Tie2 are critically involved in both normal and pathologic angiogenesis. The aim of this study was to explore the role of Ang-1, Ang-2, VEGF, and Tie2 in the development and progression of bladder cancer as well as to examine their prognostic value in this tumor type.

Experimental Design: Tumor samples of 113 bladder cancer patients, normal bladder epithelium of 5 noncancer patients, and two low-grade (UMUC3 and RT4) and two high-grade (J82 and T24) bladder cancer cell lines were analyzed by quantitative real-time PCR. The expression data were analyzed performing Wilcoxon rank-sum and Kaplan-Meier log-rank tests as well as univariate Cox analyses and Cox proportional hazards regression model.

Results: In tissues of noninvasive bladder tumors, Ang-1 expression was significantly lower (P < 0.001), whereas VEGF expression was significantly higher (P = 0.031) than in normal bladder tissue. These findings were also confirmed at the protein level by immunohistochemistry. In contrast, Tie2 and Ang-2 abundance in tumor did not differ significantly from that in normal bladder tissue. Multivariate analysis identified Ang-2 as a strong and independent predictor of tumor recurrence [hazard ratio (HR), 10.18; 95% confidence interval (95% CI), 2.69-38.49; P < 0.001] and Tie2 expression as an independent favorable prognostic factor for both metastasis (HR, 0.31; 95% CI, 0.11-0.89; P = 0.029) and disease-specific survival (HR, 0.25; 95% CI, 0.10-0.62; P = 0.003).

Conclusions: These data show the strongest change in expression of VEGF and Ang-1 in superficial bladder cancer in comparison with normal bladder epithelium and the invasive tumor stages. The prognostic significance of Ang-2 and Tie2 underlines the essential role of angiopoietins-Tie2 system in progression of bladder cancer.
Identification of PMF1 Methylation in Association with Bladder Cancer Progression
Authors: Aleman Ainel , Cebrian Virginia , Alvarez Miguel , Lopez Virginia , Orenes Esteban , Lopez-Serra Lidia , Algaba Ferran , Bellmunt Joaquin , López-Beltrán Antonio , Gonzalez-Peramato Pilar , Cordon-Cardo Carlos , García Javier , del Muro Javier García , Esteller Manel , Sánchez-Carbayo Marta
Published: December 2008

Purpose: Polyamines are important regulators of cell growth and death. The polyamine modulated factor-1 (PMF-1) is involved in polyamine homeostasis. After identifying an enriched CpG island encompassing the PMF1 promoter, we aimed at evaluating the clinical relevance of PMF1 methylation in bladder cancer.

Experimental Design: The epigenetic silencing of PMF1 by hypermethylation was tested in bladder cancer cells (n = 11) after azacytidine treatment. PMF1 methylation status was evaluated in 507 bladder tumors and 118 urinary specimens of bladder cancer patients and controls. PMF1 protein expression was analyzed by immunohistochemistry on tissue arrays containing bladder tumors for which PMF1 methylation was assessed (n = 218).

Results: PMF1 hypermethylation was associated with gene expression loss, being restored in vitro by a demethylating agent. An initial set of 101 primary frozen bladder tumors served to identify PMF1 hypermethylation in 88.1% of the cases. An independent set of 406 paraffin-embedded tumors also revealed a high PMF1 methylation rate (77.6%). PMF1 methylation was significantly associated with increasing stage (P = 0.025). Immunohistochemical analyses revealed that PMF1 methylation was associated with cytoplasmic PMF1 expression loss (P = 0.032). PMF1 protein expression patterns were significantly associated with stage (P < 0.001), grade (P < 0.001), and poor overall survival using univariate (P < 0.001) and multivariate (P = 0.011) analyses. Moreover, PMF1 methylation in urinary specimens distinguished bladder cancer patients from controls (area under the curve = 0.800).

Conclusion: PMF1 was identified to be epigenetically modified in bladder cancer. The association of PMF1 methylation with tumor progression and its diagnostic ability using urinary specimens support including PMF1 assessment for the clinical management of bladder cancer patients.
Molecular Grading of Ductal Carcinoma In situ of the Breast
Authors: Balleine Rosemary L. , Webster Lucy R. , Davis Sean , Salisbury Elizabeth L. , Palazzo Juan P. , Schwartz Gordon F. , Cornfield Dennis B. , Walker Robert L. , Byth Karen , Clarke Christine L. , Meltzer Paul S.
Published: December 2008

Purpose: Increased incidence of ductal carcinoma in situ (DCIS) associated with mammographic screening for breast cancer has emphasized the challenges of managing this condition. The aim of this study was to identify informative clinical indicators of DCIS biology by molecular profiling.

Experimental Design: Areas of in situ carcinoma, atypical ductal hyperplasia, and benign epithelium were microdissected from 46 invasive breast cancers. Oligonucleotide probes showing differential expression between DCIS associated with grade 1 and 3 invasive cancer were identified by microarray-based gene expression profiling. Expression at these probes was used to define a “molecular grade” subcategorization of all samples. The genomic basis of molecular grade was examined by array-based comparative genomic hybridization. Clinical course was examined in a cohort of 134 patients with DCIS treated by surgery alone.

Results: DCIS samples were designated as low or high molecular grade based on expression at 173 probes. The low molecular grade subgroup included low (n = 10) and intermediate (n = 11) nuclear grade DCIS as well as all samples of atypical ductal hyperplasia (n = 4) and benign epithelium (n = 7). The high molecular grade subgroup included DCIS of intermediate (n = 7) and high (n = 19) nuclear grade. The character and degree of genomic aberration were distinct between molecular grade subgroups. A classification tree model including nuclear grade and Ki67 score accurately predicted molecular grade for 95.7% of samples. In an independent cohort, this showed a pattern of rapid disease recurrence for high molecular grade DCIS.

Conclusions: Molecular profiling indicates a binary grading scheme for DCIS. This practical approach has potential to improve clinical evaluation of DCIS.