bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly Efficient Light-Emitting Diodes with Microcavities
Authors: Schubert E. F. , Hunt N. E. J. , Micovic M. , Malik R. J. , Sivco D. L. , Cho A. Y. , Zydzik G. J.
Published: October 2006

One-dimensional microcavities are optical resonators with coplanar reflectors separated by a distance on the order of the optical wavelength. Such structures quantize the energy of photons propagating along the optical axis of the cavity and thereby strongly modify the spontaneous emission properties of a photon-emitting medium inside a microcavity. This report concerns semiconductor light-emitting diodes with the photon-emitting active region of the light-emitting diodes placed inside a microcavity. These devices are shown to have strongly modified emission properties including experimental emission efficiencies that are higher by more than a factor of 5 and theoretical emission efficiencies that are higher by more than a factor of 10 than the emission efficiencies in conventional light-emitting diodes.
The "Ozone Deficit" Problem: O
2
(
X, v
≥ 26) + O(
3
P
) from 226-nm Ozone Photodissociation
Authors: Miller R. L. , Suits A. G. , Houston P. L. , Toumi R. , Mack J. A. , Wodtke A. M.
Published: October 2006

Highly vibrationally excited O
2
(
X
3
σ

g

–
,
v
≥ 26) has been observed from the photodissociation of ozone (O
3
), and the quantum yield for this reaction has been determined for excitation at 226 nanometers. This observation may help to address the "ozone deficit" problem, or why the previously predicted stratospheric O
3
concentration is less than that observed. Recent kinetic studies have suggested that O
2
(
X
3
σ

g

–
,
v
≥ 26) can react rapidly with O
2
to form O
3
+ O and have led to speculation that, if produced in the photodissociation of O
3
, this species might be involved in resolving the discrepancy. The sequence O
3
+
h
ν → O
2
(
X
3
σ

g

–
,
v
≥ 26) + O; O
2
(
X
3
σ

g

–
,
v
≥ 26) + O
2
→ O
3
+ O (where
h
ν is a photon) would be an autocatalytic mechanism for production of odd oxygen. A two-dimensional atmospheric model has been used to evaluate the importance of this new mechanism. The new mechanism can completely account for the tropical O
3
deficit at an altitude of 43 kilometers, but it does not completely account for the deficit at higher altitudes. The mechanism also provides for isotopic fractionation and may contribute to an explanation for the anomalously high concentration of heavy O
3
in the stratosphere.
Protection from Fas-Mediated Apoptosis by a Soluble Form of the Fas Molecule
Authors: Cheng Jianhua , Zhou Tong , Liu Changdan , Shapiro John P. , Brauer Matthew J. , Kiefer Michael C. , Barr Philip J. , Mountz John D.
Published: October 2006

Fas is an apoptosis-signaling receptor molecule on the surface of a number of cell types. Molecular cloning and nucleotide sequence analysis revealed a human Fas messenger RNA variant capable of encoding a soluble Fas molecule lacking the transmembrane domain because of the deletion of an exon encoding this region. The expression of soluble Fas was confirmed by flow cytometry and immunocytochemical analysis. Supernatants from cells transfected with the variant messenger RNA blocked apoptosis induced by the antibody to Fas. Levels of soluble Fas were elevated in patients with systemic lupus erythematosus, and mice injected with soluble Fas displayed autoimmune features.
A Strong Candidate for the Breast and Ovarian Cancer Susceptibility Gene
BRCA1
Authors: Miki Yoshio , Swensen Jeff , Shattuck-Eidens Donna , Futreal P. Andrew , Harshman Keith , Tavtigian Sean , Liu Qingyun , Cochran Charles , Bennett L. Michelle , Ding Wei , Bell Russell , Rosenthal Judith , Hussey Charles , Tran Thanh , McClure Melody , Frye Cheryl , Hattier Tom , Phelps Robert , Haugen-Strano Astrid , Katcher Harold , Yakumo Kazuko , Gholami Zahra , Shaffer Daniel , Stone Steven , Bayer Steven , Wray Christian , Bogden Robert , Dayananth Priya , Ward John , Tonin Patricia , Narod Steven , Bristow Pam K. , Norris Frank H. , Helvering Leah , Morrison Paul , Rosteck Paul , Lai Mei , Barrett J. Carl , Lewis Cathryn , Neuhausen Susan , Cannon-Albright Lisa , Goldgar David , Wiseman Roger , Kamb Alexander , Skolnick Mark H.
Published: October 2006

A strong candidate for the 17q-linked
BRCA1
gene, which influences susceptibility to breast and ovarian cancer, has been identified by positional cloning methods. Probable predisposing mutations have been detected in five of eight kindreds presumed to segregate
BRCA1
susceptibility alleles. The mutations include an 11-base pair deletion, a 1-base pair insertion, a stop codon, a missense substitution, and an inferred regulatory mutation. The
BRCA1
gene is expressed in numerous tissues, including breast and ovary, and encodes a predicted protein of 1863 amino acids. This protein contains a zinc finger domain in its amino-terminal region, but is otherwise unrelated to previously described proteins. Identification of
BRCA1
should facilitate early diagnosis of breast and ovarian cancer susceptibility in some individuals as well as a better understanding of breast cancer biology.
Rearrangements of Synaptic Connections in Visual Cortex Revealed by Laser Photostimulation
Authors: Dalva Matthew B. , Katz Lawrence C.
Published: October 2006

Assessing patterns of synaptic connections in the developing mammalian neocortex has relied primarily on anatomical studies. In a physiological approach described here, the patterns of synaptic connections in slices of developing ferret visual cortex were determined with scanning laser photostimulation. Functional synaptic inputs to pyramidal cells in cortical layers 2 and 3 originating from sites close to the neuronal cell body appeared at least 2 weeks before eye opening, prior to the formation of long-range horizontal connections. Extensive long-range horizontal connections appeared in the next 10 days of development. The number of local connections peaked at the time of eye opening; the number of these connections subsequently declined to the level found in the adult while the specificity of long-distance connections increased. Thus, the relative influence of local connections on the activity of layer 2 and layer 3 neurons declines as the cortex matures while the influence of longer range connections increases substantially.
Long-Term Potentiation: Evidence Against an Increase in Transmitter Release Probability in the CA1 Region of the Hippocampus
Authors: Manabe Toshiya , Nicoll Roger A.
Published: October 2006

It is widely accepted that
N
-methyl-D-aspartate (NMDA)-receptor-dependent long-term potentiation (LTP) in the CA1 region of the hippocampus is triggered postsynaptically, but there is considerable debate as to the site at which the increase in synaptic strength is expressed. The irreversible open-channel blocking action of the NMDA receptor antagonist MK-801 has been used to test whether the probability of transmitter release (
P
r
) is increased during LTP. Although the rate of decline of the amplitude of the NMDA receptor-mediated excitatory postsynaptic current (EPSC) in the presence of MK-801 strongly depends on
P
r
, the rate of decline of the EPSC evoked at synapses expressing LTP is identical to that observed at synapses not expressing LTP. These findings are difficult to reconcile with models in which the expression of LTP is due to an increase in
P
r
.
The Sverdlovsk Anthrax Outbreak of 1979
Authors: Meselson Matthew , Guillemin Jeanne , Hugh-Jones Martin , Langmuir Alexander , Popova Ilona , Shelokov Alexis , Yampolskaya Olga
Published: October 2006

In April and May 1979, an unusual anthrax epidemic occurred in Sverdlovsk, Union of Soviet Socialist Republics. Soviet officials attributed it to consumption of contaminated meat. U.S. agencies attributed it to inhalation of spores accidentally released at a military microbiology facility in the city. Epidemiological data show that most victims worked or lived in a narrow zone extending from the military facility to the southern city limit. Farther south, livestock died of anthrax along the zone's extended axis. The zone paralleled the northerly wind that prevailed shortly before the outbreak. It is concluded that the escape of an aerosol of anthrax pathogen at the military facility caused the outbreak.
RNA14 and RNA15 Proteins as Components of a Yeast Pre-mRNA 3′-End Processing Factor
Authors: Minvielle-Sebastia Lionel , Preker Pascal J. , Keller Walter
Published: October 2006

Most eukaryotic pre-messenger RNAs are processed at their 3′ ends by endonucleolytic cleavage and polyadenylation. In yeast, this processing requires polyadenylate [poly(A)] polymerase (PAP) and other proteins that have not yet been characterized. Here, mutations in the
PAP1
gene were shown to be synergistically lethal with previously identified mutations in the
RNA14
and
RNA15
genes, which suggests that their encoded proteins participate in 3′-end processing. Indeed, extracts from
rna14
and
rna15
mutants were shown to be deficient in both steps of processing. Biochemical complementation experiments and reconstitution of both activities with partially purified cleavage factor I (CF I) validated the genetic prediction.
Binding of 14-3-3 Proteins to the Protein Kinase Raf and Effects on Its Activation
Authors: Freed Ellen , Symons Marc , Macdonald Susan G. , McCormick Frank , Ruggieri Rosamaria
Published: October 2006

To identify proteins that may participate in the activation of the protein kinase Raf, proteins that interact with Raf were selected in a two-hybrid screen. Two members of the 14-3-3 protein family were isolated that interacted with both the amino terminal regulatory regions of Raf and the kinase domain of Raf, but did not compete with the guanine nucleotide-binding protein Ras for binding to Raf. 14-3-3 proteins associated with Raf in mammalian cells and accompanied Raf to the membrane in the presence of activated Ras. In yeast cells expressing Raf and MEK, mammalian 14-3-3 ζ or 14-3-3 ζ activated Raf to a similar extent as did expression of Ras. Therefore, 14-3-3 proteins may participate in or be required for the regulation of Raf function. These findings suggest a role for 14-3-3 proteins in Raf-mediated signal transduction.
Inhibitory CA1-CA3-Hilar Region Feedback in the Hippocampus
Authors: Sik Attila , Ylinen Aarne , Penttonen Markku , Buzsáki György
Published: October 2006

The organization of the hippocampus is generally thought of as a series of cell groups that form a unidirectionally excited chain, regulated by localized inhibitory circuits. With the use of in vivo intracellular labeling, histochemical, and extracellular tracing methods, a longitudinally widespread, inhibitory feedback in rat brain from the CA1 area to the CA3 and hilar regions was observed. This long-range, cross-regional inhibition may allow precise synchronization of population activity by timing the occurrence of action potentials in the principal cells and may contribute to the coordinated induction of synaptic plasticity in distributed networks.
Synergistic Activation of Transcription by Bacteriophage λ cI Protein and
E. coli
cAMP Receptor Protein
Authors: Joung J. Keith , Koepp Deanna M. , Hochschild Ann
Published: October 2006

Two heterologous prokaryotic activators, the bacteriophage λcI protein (λcI) and the
Escherichia coli
cyclic AMP receptor protein (CRP), were shown to activate transcription synergistically from an artificial promoter bearing binding sites for both proteins. The synergy depends on a functional activation (positive control) surface on each activator. These results imply that both proteins interact directly with RNA polymerase and thus suggest a precise mechanism for transcriptional synergy: the interaction of two activators with two distinct surfaces of RNA polymerase.
Specific Cleavage of Model Recombination and Repair Intermediates by the Yeast Rad1-Rad10 DNA Endonuclease
Authors: Bardwell A. Jane , Bardwell Lee , Tomkinson Alan E. , Friedberg Errol C.
Published: October 2006

The
RAD1
and
RAD10
genes of
Saccharomyces cerevisiae
are required for both nucleotide excision repair and certain mitotic recombination events. Here, model recombination and repair intermediates were used to show that Rad1-Rad10-mediated cleavage occurs at duplex-single-strand junctions. Moreover, cleavage occurs only on the strand containing the 3′ single-stranded tail. Thus, both biochemical and genetic evidence indicate a role for the Rad1-Rad10 complex in the cleavage of specific recombination intermediates. Furthermore, these data suggest that Rad1-Rad10 endonuclease incises DNA 5′ to damaged bases during nucleotide excision repair.
Direct Observation of Tube-Like Motion of a Single Polymer Chain
Authors: Perkins Thomas T. , Smith Douglas E. , Chu Steven
Published: October 2006

Tube-like motion of a single, fluorescently labeled molecule of DNA in an entangled solution of unlabeled lambda-phage DNA molecules was observed by fluorescence microscopy. One end of a 16- to 100-micrometer-long DNA was attached to a 1-micrometer bead and moved with optical tweezers. The molecule was stretched into various conformations having bends, kinks, and loops. As the polymer relaxed, it closely followed a path defined by its initial contour. The relaxation time of the disturbance caused by the bead was roughly 1 second, whereas tube-like motion in small loops persisted for longer than 2 minutes. Tube deformation, constraint release, and excess chain segment diffusion were also observed. These observations provide direct evidence for several key assumptions in the reptation model developed by de Gennes, Edwards, and Doi.
Erratum: Livermore Faces Forces of Change
Authors: Anderson Christophe
Published: October 2006

A graph showing a declining work force that accompanied Christopher Anderson's News & Comment article "Livermore faces forces of change" (15 Apr., p. 336) was improperly labeled. The graph depicted only the number of employees in the defense programs at Lawrence Livermore National Laboratory, not the overall staff levels at the lab.
A Protein Phosphatase 2C Involved in ABA Signal Transduction in
Arabidopsis thaliana
Authors: Meyer Knut , Leube Martin P. , Grill Erwin
Published: October 2006

The plant hormone abscisic acid (ABA) mediates various responses such as stomatal closure, the maintenance of seed dormancy, and the inhibition of plant growth. All three responses are affected in the ABA-insensitive mutant
abi1
of
Arabidopsis thaliana
, suggesting that an early step in the signaling of ABA is controlled by the
ABI1
locus. The
ABI1
gene was cloned by chromosome walking, and a missense mutation was identified in the structural gene of the
abi1
mutant. The
ABI1
gene encodes a protein with high similarity to protein serine or threonine phosphatases of type 2C with the novel feature of a putative Ca
2+
binding site. Thus, the control of the phosphorylation state of cell signaling components by the
ABI1
product could mediate pleiotropic hormone responses.
Anergic T Cells as Suppressor Cells in Vitro
Authors: Lombardi Giovanna , Sidhu Sid , Batchelor Richard , Lechler Robert
Published: October 2006

T cell-mediated suppression is an established phenomenon, but its underlying mechanisms are obscure. An in vitro system was used to test the possibility that anergic T cells can act as specific suppressor cells. Anergic human T cells caused inhibition of antigen-specific and allospecific T cell proliferation. In order for the inhibition to occur, the anergic T cells had to be specific for the same antigen-presenting cells (APCs) as the T cells that were suppressed. The mechanism of this suppression appears to be competition for the APC surface and for locally produced interleukin-2.
Human Severe Combined Immunodeficiency Due to a Defect in ZAP-70, a T Cell Tyrosine Kinase
Authors: Elder Melissa E. , Lin Dong , Clever Jared , Chan Andrew C. , Hope Thomas J. , Weiss Arthur , Parslow Tristram G.
Published: October 2006

A homozygous mutation in the kinase domain of ZAP-70, a T cell receptor-associated protein tyrosine kinase, produced a distinctive form of human severe combined immunodeficiency. Manifestations of this disorder included profound immunodeficiency, absence of peripheral CD8
+
T cells, and abundant peripheral CD4
+
T cells that were refractory to T cell receptor-mediated activation. These findings demonstrate that ZAP-70 is essential for human T cell function and suggest that CD4
+
and CD8
+
T cells depend on different intracellular signaling pathways to support their development or survival.
Sequencing of the
porB
Gene: a Step toward a True Characterization of
Neisseria meningitidis
Authors: Abad R. , Alcalá B. , Salcedo C. , Enríquez R. , Uría M. J. , Diez P. , Vázquez J. A.
Published: October 2006

Variations in class 2/3 (PorB) proteins form the basis for meningococcal serotyping. Antibodies against these proteins are bactericidal, making serotyping results useful not only for epidemiological surveillance of meningococcal disease but also for identifying potential vaccine components. A total of 20 to 60% of meningococcal B and C isolates from any given population are nontypeable (NT) using a panel of monoclonal antibodies. To analyze the mechanisms responsible for the nonserotypeability characteristic in
Neisseria meningitidis
, we (i) established the nucleotide sequences of
porB
gene in 146 meningococcal strains (95 not recognized by the serotyping panel), (ii) identified 18 new allelic variants of the
porB
gene, (iii) correlated allelic variants with serotypes, (iv) suggest the nontypeability characteristic in those 95 NT strains, and (v) reject the possibility of variation in the levels of PorB expression.
Emergency department screening for risk for post-traumatic stress disorder among injured children: Table 1
Authors: Ward-Begnoche W L , Aitken M E , Liggin R , Mullins S H , Kassam-Adams N , Marks A , Winston F K
Published: October 2006

Objective:To discuss the successes and challenges associated with the implementation of a post-traumatic stress disorder (PTSD) screening tool in two pediatric emergency departments (ED).

Methods:The STEPP screening tool has been developed previously on an inpatient population of motor vehicle trauma patients. It was applied here to the general ED population at two different pediatric trauma centers. Nurse screeners were trained and a convenience sample of patients with unintentional injuries who met study criteria were screened in the ED. Feedback from nurse screeners was obtained.

Results:The process of implementing a screening tool to identify patients and their families significantly at risk for PTSD symptomatology presented some barriers, but overall acceptability of the process was high for both the emergency department staff and the patient. Recommendations for others considering implementation of screening programs in the ED are offered.

Conclusions:Future research using screening protocols in the ED should, in their design, attempt to capitalize on the successes identified in the current protocol and circumvent barriers also encountered.
PHASE COHERENCE OF THE ELECTRON AND HOLE IN A METALLIC FILM IN PROXIMITY WITH A SUPERCONDUCTOR
Authors: YU H. L. , ZHENG Z. M. , SHEN R. , SHAO L. B. , WANG B. G.
Published: October 2006

The scattering matrix approach is applied to the study of tunneling spectra in a metallic film in proximity with a superconductor. The abnormal minigap in tunneling conductance is attributed to the phase coherence of electrons and Andreev-reflected holes in the metallic film. The coherent transport in the metal leads to a fully opened minigap, whose width decreases with increase in the metallic film thickness, while the sequential component results in non-zero densities of states within the minigap. The calculated results provide a reasonable explanation for abnormal minigap behavior observed in recent experiments.
EVOLUTION OF LUMINESCENCE SPECTRA OF Ce3+-ION IN THE SOLID SOLUTIONS Ca1-xSrxS
Authors: KRACHNI O. , GUERBOUS L. , LOUAIL L.
Published: October 2006

Luminescence spectra of Ce 3+-ion in Ca 1-x Sr x S solid solutions have been investigated. It has been shown that the evolution of Ce 3+ excitation and emission spectra through the concentration range may be interpreted in correlation with the variations, with the host lattice composition, of the lattice constant, the local structure in the activator neighborhood and the band gap. Under activator excitation, in addition to the two conventional bands, an additional band peaking at about 650 nm was observed (mainly in SrS ) and was related to the contamination of the samples as a consequence of extended storage. Except for this band, the luminescence properties did not change relatively to those obtained previously on the same samples. The most drastic modification affected SrS:Ce 3+, despite the fact that all the samples have been stored in the same conditions.
Liver I/R injury is improved by the arginase inhibitor, Nω-hydroxy-nor-l-arginine (nor-NOHA)
Authors: Reid Kaye M. , Tsung Allan , Kaizu Takahashi , Jeyabalan Geetha , Ikeda Atsushi , Shao Lifang , Wu Guoyao , Murase Noriko , Geller David A.
Published: October 2006

Liver ischemia-reperfusion (I/R) injury is associated with profound arginine depletion due to arginase release from injured hepatocytes. The purpose of this study was to determine whether arginase inhibition with Nω-hydroxy-nor-l-arginine (nor-NOHA) would increase circulating arginine levels and decrease hepatic damage during liver I/R injury. The effects of nor-NOHA were initially tested in normal animals to determine in vivo toxicity. In the second series of experiments, orthotopic syngeneic liver transplantation (OLT) was performed after 18 h of cold ischemia time in Lewis rats. Animals were given nor-NOHA (100 mg/kg) or saline before and after graft reperfusion. In normal animals treated with nor-NOHA, there were no histopathological changes to organs, liver enzymes, serum creatinine, or body weight. In the OLT model, animals treated with saline exhibited markedly elevated serum transaminases and circulating arginase protein levels. Nor-NOHA administration blunted the increase in serum arginase activity by 80% and preserved serum arginine levels at 3 h after OLT. Nor-NOHA treatment reduced post-OLT serum liver enzyme release by 50%. Liver histology (degree of necrosis) in nor-NOHA-treated animals was markedly improved compared with the saline-treated group. Furthermore, use of the arginase inhibitor nor-NOHA did not influence polyamine synthesis owing to the decrease in ornithine levels. Arginase blockade represents a potentially novel strategy to combat hepatic I/R injury associated with liver transplantation.
Regulation of hdm2 by Stress-Induced hdm2alt1 in Tumor and Nontumorigenic Cell Lines Correlating with p53 Stability
Authors: Dias Chrisanne S. , Liu Yan , Yau Amy , Westrick Lindsay , Evans Susan C.
Published: October 2006

Alternative and aberrant splicing of hdm2 occurs in tumor and normal tissues. However, the factors that induce these splice variants and whether they are translated to protein products in vivo is unknown, making it difficult to decipher which of these hdm2 transcripts have a normal physiologic function or contribute to carcinogenesis. We investigated the conditions that induce this post-transcriptional modification of hdm2 in tumor and nontumorigenic cell lines. We showed that UV and γ radiation as well as cisplatin treatment induced alternative splicing of hdm2, which resulted in a single splice variant, hdm2alt1, irrespective of the cell type. Interestingly, the mechanism of UV-induced splicing is independent of p53 status. Immunoanalysis revealed that, after UV radiation, HDM2ALT1 protein was expressed and interacted with HDM2 that correlated to increased p53 protein levels and its accumulation in the nucleus, whereas HDM2 localized more to the cytoplasm with a decrease in its RNA and protein level. We propose that stress-induced HDM2ALT1 regulates HDM2 at two levels, RNA and protein, further modulating the p53-HDM2 interaction or interactions of HDM2 with other cell cycle regulatory proteins. This kind of regulation may possibly restrict oncogenic functions of HDM2 and contribute to the many protective responses triggered by certain stress signals. Our data imply that HDM2ALT1 possesses a normal physiologic function in damaged cells, perhaps facilitating cellular defense. (Cancer Res 2006; 66(19): 9467-73)
Pyridone 6, A Pan-Janus–Activated Kinase Inhibitor, Induces Growth Inhibition of Multiple Myeloma Cells
Authors: Pedranzini Laura , Dechow Tobias , Berishaj Marjan , Comenzo Raymond , Zhou Ping , Azare Janeen , Bornmann William , Bromberg Jacqueline
Published: October 2006

Interleukin-6 (IL-6) and the subsequent Janus-activated kinase (JAK)-dependent signaling pathways play a critical role in the pathogenesis of multiple myeloma. Here, we compared the sensitivity and specificity of a novel pan-JAK inhibitor, tetracyclic pyridone 6 (P6), with that of AG490 in a panel of myeloma-derived cell lines. P6 induced growth arrest and subsequent apoptosis of the IL-6-dependent hybridoma and myeloma-derived cell lines (B9 and INA-6) grown either in IL-6-containing medium or in the presence of bone marrow–derived stromal cells (BMSC) using much lower concentrations of drug and with significantly faster kinetics than AG490. Myeloma-derived cell lines, which either express constitutively activated JAK/signal transducers and activators of transcription (STAT) 3 (U266) or are IL-6 growth stimulated (KMS11), are partially growth inhibited by P6. However, P6 does not inhibit the growth of myeloma-derived cell lines lacking activated JAKs/STATs nor does it inhibit mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase activity compared with AG490, which led to activation of ERK and induced robust apoptosis of all the examined cell lines. Finally, P6 inhibited the growth of primary myeloma patient samples grown in the presence of BMSCs. Thus, P6 is a more sensitive and specific inhibitor of JAK-STAT3 activity compared with AG490 and potently inhibited the growth of primary myeloma cells and myeloma-derived cell lines grown on BMSCs. (Cancer Res 2006; 66(19): 9714-21)
Identification of an Agent Selectively Targeting DPC4 (Deleted in Pancreatic Cancer Locus 4)–Deficient Pancreatic Cancer Cells
Authors: Wang Hong , Han Haiyong , Von Hoff Daniel D.
Published: October 2006

One of the most common types of genetic alterations in cancer is the loss-of-function mutations in tumor-suppressor genes. Such mutations are usually very specific to cancer cells and present attractive and unique opportunities for therapeutic interventions. However, for various reasons, antitumor agents that target loss-of-function mutations have not been readily identified. In this report, using the deleted in pancreatic cancer locus 4 (DPC4) gene in pancreatic cancer as an example, we show the feasibility of a novel screening strategy, which we have named Pharmacological Synthetic Lethal Screening, for the identification of agents that selectively target cancer cells with loss-of-function mutations. We created DPC4 isogenic cell lines through the restoration of wild-type DPC4 in a pancreatic cancer cell line, BxPC-3, whose DPC4 gene was homozygously deleted. The isogenic cell lines were then used in the Pharmacological Synthetic Lethal Screening to evaluate compound libraries for antiproliferative activity and selectivity against DPC4 deficiency. After screening 19,590 compounds, we identified one lead compound, UA62001, which showed 4.6-fold selectivity against DPC4 deficiency in the DPC4 isogenic cell lines. UA62001 selectivity was also seen in another set of DPC4 isogenic cell lines generated by small interfering RNA knockdown. In addition, UA62001 was evaluated in commonly used pancreatic cancer cell lines. A fairly good correlation between DPC4 deficiency and UA62001 sensitivity was observed. Cell cycle analysis indicates that UA62001 arrests cells in S and G2-M phases. The results of microarray gene expression profiling and quantitative real-time reverse transcription-PCR suggest that cyclin B/CDC2 and minichromosome maintenance complexes might be the downstream cellular targets of UA62001. (Cancer Res 2006; 66(19): 9722-30)
Targeting the Lymphotoxin-β Receptor with Agonist Antibodies as a Potential Cancer Therapy
Authors: Lukashev Matvey , LePage Doreen , Wilson Cheryl , Bailly Véronique , Garber Ellen , Lukashin Alex , Ngam-ek Apinya , Zeng Weike , Allaire Norman , Perrin Steve , Xu Xianghong , Szeliga Kendall , Wortham Kathleen , Kelly Rebecca , Bottiglio Cindy , Ding Jane , Griffith Linda , Heaney Glenna , Silverio Erika , Yang William , Jarpe Matt , Fawell Stephen , Reff Mitchell , Carmillo Amie , Miatkowski Konrad , Amatucci Joseph , Crowell Thomas , Prentice Holly , Meier Werner , Violette Shelia M. , Mackay Fabienne , Yang Dajun , Hoffman Robert , Browning Jeffrey L.
Published: October 2006

The lymphotoxin-β receptor (LTβR) is a tumor necrosis factor receptor family member critical for the development and maintenance of various lymphoid microenvironments. Herein, we show that agonistic anti-LTβR monoclonal antibody (mAb) CBE11 inhibited tumor growth in xenograft models and potentiated tumor responses to chemotherapeutic agents. In a syngeneic colon carcinoma tumor model, treatment of the tumor-bearing mice with an agonistic antibody against murine LTβR caused increased lymphocyte infiltration and necrosis of the tumor. A pattern of differential gene expression predictive of cellular and xenograft response to LTβR activation was identified in a panel of colon carcinoma cell lines and when applied to a panel of clinical colorectal tumor samples indicated 35% likelihood a tumor response to CBE11. Consistent with this estimate, CBE11 decreased tumor size and/or improved long-term animal survival with two of six independent orthotopic xenografts prepared from surgical colorectal carcinoma samples. Targeting of LTβR with agonistic mAbs offers a novel approach to the treatment of colorectal and potentially other types of cancers. (Cancer Res 2006; 66(19): 9617-24)
PRL-3 Initiates Tumor Angiogenesis by Recruiting Endothelial Cells In vitro and In vivo
Authors: Guo Ke , Li Jie , Wang Haihe , Osato Motomi , Tang Jing Ping , Quah Samantha Yiling , Gan Bin Qi , Zeng Qi
Published: October 2006

We show here that PRL-3 protein is expressed in fetal heart, developing blood vessels, and pre-erythrocytes but not in their mature counterparts. These observations imply that PRL-3 may be involved in the early development of the circulatory system. Because PRL-3 mRNA had been reported to be consistently elevated in metastatic samples derived from colorectal cancers, we attempted to investigate if PRL-3 might be involved in tumor angiogenesis and if PRL-3-expressing cells could cross-talk to human umbilical vascular endothelial cells (HUVEC) by using an in vitro coculture system. HUVECs were grown with fibroblasts, which were later overlaid with PRL-3-expressing cells. We observed that both PRL-3-expressing Chinese hamster ovary (CHO) cells and PRL-3-expressing DLD-1 human colon cancer cells could redirect the migration of HUVECs toward them; in addition, PRL-3-expressing DLD-1 cells could enhance HUVEC vascular formation. In vivo injection of PRL-3-expressing CHO cells into nude mice to form local tumors resulted in the recruitment of host endothelial cells into the tumors and initiation of angiogenesis. We further showed that PRL-3-expressing cells reduced interleukin-4 (IL-4) expression levels and thus attenuated IL-4 inhibitory effects on the HUVEC vasculature. Our findings provide direct evidence that PRL-3 may be involved in triggering angiogenesis and establishing microvasculature and it may serve as an attractive therapeutic target with respect to both angiogenesis and cancer metastasis. (Cancer Res 2006; 66(19): 9625-35)
Absence of CD9 Enhances Adhesion-Dependent Morphologic Differentiation, Survival, and Matrix Metalloproteinase-2 Production in Small Cell Lung Cancer Cells
Authors: Saito Yoshiyuki , Tachibana Isao , Takeda Yoshito , Yamane Hiroyuki , He Ping , Suzuki Mayumi , Minami Seigo , Kijima Takashi , Yoshida Mitsuhiro , Kumagai Toru , Osaki Tadashi , Kawase Ichiro
Published: October 2006

While adhering to extracellular matrix proteins in vitro and in vivo, small cell lung cancer (SCLC) cells frequently show morphologic differentiation and are protected from apoptosis. Integrin β1–mediated protein phosphorylation is suggested to be an essential signaling event in these processes. CD9 is an almost ubiquitously expressed tetraspanin protein that suppresses tumor progression by regulating cell motility and signaling through complex formation with β1 integrins. We reported previously that, among tetraspanins, CD9 is selectively absent in most SCLC cells and that ectopic expression of CD9 suppresses their motility. Here, we show that the ectopic expression of CD9 suppressed neurite-like process outgrowth and promoted apoptotic death of SCLC cells that were adherent to fibronectin in serum-starved conditions. This correlated with attenuation of adhesion-dependent phosphorylation of Akt but not that of focal adhesion kinase or c-Jun NH2-terminal kinase. Treatment of CD9− parent cells with a phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002, inhibited process outgrowth and survival, suggesting that PI3K/Akt signaling is required for the morphologic change and cell survival. Production of matrix metalloproteinase (MMP)-2 was likewise suppressed in the CD9 transfectants and in LY294002-treated parent cells. These results suggest that the absence of CD9 in SCLC cells may contribute to postadhesive morphologic differentiation, survival, and MMP-2 production via PI3K/Akt pathway. (Cancer Res 2006; 66(19): 9557-65)
Inhibition of p53 Response in Tumor Stroma Improves Efficacy of Anticancer Treatment by Increasing Antiangiogenic Effects of Chemotherapy and Radiotherapy in Mice
Authors: Burdelya Lyudmila G. , Komarova Elena A. , Hill Jason E. , Browder Timothy , Tararova Natalia D. , Mavrakis Lori , DiCorleto Paul E. , Folkman Judah , Gudkov Andrei V.
Published: October 2006

Inactivation of p53 function, which frequently occurs in tumors, can significantly modulate tumor cell sensitivity to radiation and chemotherapeutic drugs. However, in addition to acting on malignant cells, anticancer agents act on the cells of tumor stroma, causing activation of a p53 response. The effect of this response on treatment outcome has been the subject of the present study. Tumors with p53-deficient stroma were generated using mouse tumorigenic packaging cells that produce a p53 inhibitory retrovirus, encoding a dominant-negative p53 mutant. Tumors maintaining wild-type p53 in their stroma were formed by cells of similar origin but deficient in retroviral production due to the deletion of the packaging signal in the retroviral vector. Comparison of these tumor models, differing only in p53 status of their stromas, showed that tumors with p53-deficient stroma were significantly more sensitive to experimental chemotherapy and radiotherapy. A similar effect was achieved when anticancer treatment was combined with pharmacologic suppression of p53 by the cyclic form of pifithrin α, a small-molecule inhibitor of p53. Potentiation of the anticancer effect of chemotherapy and radiotherapy by p53 suppression in the tumor stroma is likely to be due to the increased sensitivity of p53-deficient endothelium to genotoxic stress as shown both in cell culture and in experimental tumors. Thus, reversible pharmacologic suppression of p53 may be a viable approach to improving anticancer treatment via an enhanced antiangiogenic effect of chemotherapy and radiotherapy. (Cancer Res 2006; 66(19): 9356-61)
Comprehensive Assessment of Genetic Variation ofCatechol-O-Methyltransferaseand Breast Cancer Risk
Authors: Gaudet Mia M. , Chanock Stephen , Lissowska Jolanta , Berndt Sonja I. , Peplonska Beata , Brinton Louise A. , Welch Robert , Yeager Meredith , Bardin-Mikolajczak Alicja , Garcia-Closas Montserrat
Published: October 2006

Because catechol-O-methyltransferase (COMT) catalyzes the addition of methyl groups to stabilize catechol estrogens that may induce DNA damage, genetic variants could influence breast cancer risk. To comprehensively characterize genetic variation in this gene, we selected haplotype-tagging single nucleotide polymorphisms (htSNP) in COMT. A total of 11 htSNPs (including COMT Val158Met) were selected based on the resequencing and dense genotyping approach of the Breast and Prostate Cancer Cohort Consortium. htSNPs were genotyped in a population-based, case-control study in Poland (1,995 cases and 2,296 controls). Individual SNPs were not significantly associated with risk. Haplotypes were estimated using the expectation-maximization algorithm. Overall differences in the haplotype distribution between cases and controls were assessed using a global score test. The TGAG haplotype (frequent in 4.3% of controls), in a linkage disequilibrium (LD) block that included the 3′ untranslated region (UTR) of COMT, was associated with breast cancer risk (odds ratio, 1.29; 95% confidence interval, 1.06-1.58) compared with the most common haplotype TGAA; however, the global test for haplotype associations was not significant (P = 0.09). Haplotypes in another LD block, which included COMT Val158Met, were not associated with breast cancer risk (global P = 0.76). Haplotype-breast cancer risk associations were not significantly modified by hormonally related risk factors, family history of breast cancer, or tumor characteristics. In summary, our data does not support a substantial overall association between COMT haplotypes and breast cancer. The suggestion of increased risk associated with a haplotype in the 3′ UTR of COMT needs to be confirmed in independent study populations. (Cancer Res 2006; 66(19): 9781-5)
The 3p21.3 Tumor Suppressor NPRL2 Plays an Important Role in Cisplatin-Induced Resistance in Human Non–Small-Cell Lung Cancer Cells
Authors: Ueda Kentaro , Kawashima Hiroyuki , Ohtani Shoichiro , Deng Wu-Guo , Ravoori Murali , Bankson Jim , Gao Boning , Girard Luc , Minna John D. , Roth Jack A. , Kundra Vikas , Ji Lin
Published: October 2006

NPRL2 is one of the novel candidate tumor suppressor genes identified in the human chromosome 3p21.3 region. The NPRL2 has shown potent tumor suppression activity in vitro and in vivo and has been suggested to be involved in DNA mismatch repair, cell cycle checkpoint signaling, and regulation of the apoptotic pathway. In this study, we analyzed the endogenous expression of the NPRL2 protein and the cellular response to cisplatin in 40 non–small-cell lung cancer cell lines and found that expression of NPRL2 was significantly and reciprocally correlated to cisplatin sensitivity, with a Spearman correlation coefficient of −0.677 (P < 0.00001). Exogenously introduced expression of NPRL2 by N-[1-(2,3-dioleoyloxyl)propyl]-NNN-trimethylammoniummethyl sulfate:cholesterol nanoparticle–mediated gene transfer significantly resensitized the response to cisplatin, yielding a 40% greater inhibition of tumor cell viability and resulting in a 2- to 3-fold increase in induction of apoptosis by activation of multiple caspases in NPRL2-transfected cells compared with untransfected cells at an equal dose of cisplatin. Furthermore, a systemic treatment with a combination of NPRL2 nanoparticles and cisplatin in a human H322 lung cancer orthotopic mouse model significantly enhanced the therapeutic efficacy of cisplatin and overcame cisplatin-induced resistance (P < 0.005). These findings implicate the potential of NPRL2 as a biomarker for predicting cisplatin response in lung cancer patients and as a molecular therapeutic agent for enhancing response and resensitizing nonresponders to cisplatin treatment. (Cancer Res 2006; 66(19): 9682-90)
Distinct Effects of Annexin A7 and p53 on Arachidonate Lipoxygenation in Prostate Cancer Cells Involve 5-Lipoxygenase Transcription
Authors: Torosyan Yelizaveta , Dobi Albert , Naga Shanmugam , Mezhevaya Katerina , Glasman Mirta , Norris Christine , Jiang Guisen , Mueller Gregory , Pollard Harvey , Srivastava Meera
Published: October 2006

Tumor suppressor function for Annexin A7 (ANXA7; 10q21) is based on cancer-prone phenotype in Anxa7(+/−) mouse and ANXA7 prognostic role in human cancers. Because ANXA7-caused liposome aggregation can be promoted by arachidonic acid (AA), we hypothesized that the phospholipid-binding tumor suppressor ANXA7 is associated with AA cascade. In a comparative study of ANXA7 versus canonical tumor suppressor p53 effects on AA lipoxygenation pathway in the p53-mutant and androgen-insensitive DU145 prostate cancer cells, both tumor suppressors altered gene expression of major 5-lipoxygenase (LOX) and 15-LOXs, including response to T helper 2 (Th2)-cytokine [interleukin-4 (IL-4)] and endogenous steroids (mimicked by dexamethasone). Wild-type and mutant ANXA7 distinctly affected expression of the dexamethasone-induced 15-LOX-2 (a prostate-specific endogenous tumor suppressor) as well as the IL-4-induced 15-LOX-1. On the other hand, wild-type p53 restored 5-LOX expression in DU145 to levels comparable to benign prostate epithelial cells. Using mass spectrometry of DNA affinity–enriched nuclear proteins, we detected different proteins that were bound to adjacent p53 and estrogen response elements in the 5-LOX promoter in DU145 cells introduced with ANXA7 versus p53. Sex hormone regulator 17-β hydroxysteroid dehydrogenase 4 was identified under p53 introduction, which induced the 5-LOX expression. Meantime, nuclear proteins bound to the same 5-LOX promoter site under introduction of ANXA7 (that was associated with the repressed 5-LOX) were identified as zinc finger proteins ZNF433 and Aiolos, pyrin domain–containing NALP10, and the p53-regulating DNA repair enzyme APEX1. Thus, ANXA7 and p53 can distinctly regulate LOX transcription that is potentially relevant to the AA-mediated cell growth control in tumor suppression. (Cancer Res 2006; 66(19): 9609-16)
The COOH-Terminal Globular Domain of Fibrinogen γ Chain Suppresses Angiogenesis and Tumor Growth
Authors: Akakura Nobuaki , Hoogland Case , Takada Yoko K. , Saegusa Jun , Ye Xiaojing , Liu Fu-Tong , Cheung Anthony Tze-Wai , Takada Yoshikazu
Published: October 2006

Fibrinogen is a major plasma protein (350 kDa) that induces proliferative signals by serving as a scaffold to support the binding of growth factors and to promote the cellular responses of adhesion, proliferation, and migration during wound healing, angiogenesis, and tumor growth. Fibrin(ogen) degradation products generated during fibrinolysis are implicated in tissue injury. The fibrinogen γ chain has a COOH-terminal globular domain (γC, residues 151-411 of the γ chain, 30 kDa) to which several integrin cell adhesion receptors (e.g., platelet αIIbβ3, endothelial αvβ3, and leukocyte αMβ2) bind. Integrins play a critical role in signal transduction from fibrin(ogen). We found that γC and its truncation mutant (designated γC399tr), with a deletion of the COOH-terminal 12 residues, induced apoptosis of endothelial cells and blocked tube formation of endothelial cells. DLD-1 human colon cancer cells that secrete γC or γC399tr grew at similar levels in vitro but grew much slower in vivo than mock-transfected cells. The recombinant purified γC399tr fragment markedly suppressed tumor growth, development of intratumoral vasculature, and tumor metastasis in vivo in the highly metastatic Met-1 breast cancer model. The determinant responsible for binding to endothelial cells is cryptic in native fibrinogen but is exposed in γC and γC399tr. These results suggest that fibrinogen has a novel cryptic determinant, which can exert apoptosis-inducing activity on endothelial cells when exposed, and polypeptides containing this determinant have therapeutic potential. (Cancer Res 2006; 66(19): 9691-7)
An EBF3-Mediated Transcriptional Program That Induces Cell Cycle Arrest and Apoptosis
Authors: Zhao Lisa Y. , Niu Yuxin , Santiago Aleixo , Liu Jilin , Albert Sara H. , Robertson Keith D. , Liao Daiqing
Published: October 2006

In a genome-wide screen for putative tumor suppressor genes, the EBF3 locus on the human chromosome 10q26.3 was found to be deleted or methylated in 73% of the examined cases of brain tumors. EBF3 is expressed in normal brain but is silenced in brain tumors. Therefore, it is suggested that EBF3 is a tumor suppressor. However, it remains unknown whether inactivation of EBF3 locus also occurs in other types of tumors and what functions of EBF3 underlie EBF3-mediated tumor suppression. We show here that expression of EBF3 resulted in cell cycle arrest and apoptosis. The expression of cyclin-dependent kinase inhibitors was profoundly affected with early activation and then repression of p21cip1/waf1 and persistent activation of both p27kip1 and p57kip2, whereas genes involved in cell survival and proliferation were suppressed. EBF3 bound directly to p21cip1/waf1 promoter and regulated transcription from both p21cip1/waf1 and p27kip1 promoters in reporter assays. Apoptosis occurred 48 hours after EBF3 expression with caspase-3 activation. Silencing of the EBF3 locus was observed in brain, colorectal, breast, liver, and bone tumor cell lines and its reactivation was achieved on treatment with 5-aza-2′-deoxycytidine and trichostatin A in a significant portion of these tumor cells. Therefore, EBF3 regulates a transcriptional program underlying a putative tumor suppression pathway. (Cancer Res 2006; 66(19): 9445-52)
Estrogen-Induced Activation of Mammalian Target of Rapamycin Is Mediated via Tuberin and the Small GTPase Ras Homologue Enriched in Brain
Authors: Yu Jane , Henske Elizabeth Petri
Published: October 2006

Inhibitors of the mammalian target of rapamycin (mTOR) are currently in clinical trials for the treatment of breast cancer. The mechanisms through which mTOR are activated in breast cancer and the relationship of mTOR activation to steroid hormones, such as estrogen, that are known to influence breast cancer pathogenesis, are not yet understood. Using MCF-7 cells as a model, we found that 17-β estradiol (E2) rapidly increased the phosphorylation of downstream targets of mTOR: p70 ribosomal protein S6 kinase, ribosomal protein S6, and eukaryotic initiation factor 4E-binding protein 1. The phosphoinositide-3-kinase inhibitor, wortmannin, and the mTOR inhibitor, rapamycin, blocked E2-induced activation of p70 ribosomal protein S6 kinase. We hypothesized that tuberin and the small GTPase Ras homologue enriched in brain (Rheb), regulators of the mTOR pathway, mediate E2-induced activation of mTOR. Consistent with this hypothesis, E2 rapidly (within 5 minutes) stimulated tuberin phosphorylation at T1462, a site at which Akt phosphorylates and inactivates tuberin. E2 also rapidly decreased the inactive, GDP-bound form of Rheb. Finally, we found that small interfering RNA down-regulation of endogenous Rheb blocked the E2-stimulated proliferation of MCF-7 cells, demonstrating that Rheb is a key determinant of E2-dependent cell growth. Taken together, these data reveal that the TSC/Rheb/mTOR pathway plays a critical role in the regulation of E2-induced proliferation, and highlight Rheb as a novel molecular target for breast cancer therapy. (Cancer Res 2006; 66(19): 9461-6)