bluuebunny/crossref_metadata_2025 huggingface dataset:
High Curie Temperature and Nano-Scale Spinodal Decomposition Phase in Dilute Magnetic Semiconductors
Authors: Sato Kazunori , Katayama-Yoshida Hiroshi , Dederichs Peter H.
Published: September 2005

We show that spinoadal decomposition phase in dilute magnetic semiconductors (DMS) offers the possibility to have high Curie temperatures (T
C) even if the magnetic exchange interaction is short ranged. The spinodal decomposition is simulated by applying the Monte Carlo method to the Ising model with realistic (ab initio) chemical pair interactions between magnetic impurities in DMS. Curie temperatures are estimated by the random phase approximation with taking disorder into account. It is found that the spinodal decomposition phase inherently occurs in DMS due to strong attractive interactions between impurities. This phase decomposition supports magnetic network over the dimension of the crystal resulting in a high-T
C phase.
Microstructural and Optical Evaluation of Nitride Light-Emitting Diodes and II–VI Distributed Bragg Reflectors Combined by Direct Wafer Bonding
Authors: Murai Akihiko , Kruse Carsten , Samonji Katsuya , McCarthy Lee , Speck James S. , Mishra Umesh K. , DenBaars Steven P. , Hommel Detlef
Published: September 2005

We report on the structural and optical characteristics of InGaN/GaN light-emitting diodes (LEDs) and n-type ZnSe-based II–VI distributed Bragg reflectors combined by direct wafer bonding. Reflectivity and transmission electron microscopy (TEM) measurements were performed. The bonded sample exhibited a higher reflectivity at the wavelength of 510 nm than a control LED with an Al cap. Samples were bonded at 270°C for 60 min or at 650°C for 5 min. Cross-sectional TEM revealed a uniform wafer-bonded interface with no voids or cavities for the low temperature sample, while the sample bonded at a higher temperature was observed to have lens-shaped cavities at semiconductor interfaces.
Remote Calibration of Length Standards Using 47-km-Long Optical Fiber Network
Authors: Matsumoto Hirokazu , Sasaki Kaoru , Hirai Akiko
Published: September 2005

The information of practical length standards is transmitted through 47-km-long optical fiber network between Tsuchiura city and Kashiwa city in Japan. Interference fringes are generated when the optical path difference of a low-coherence interferometer in the Tsuchiura relay station compensates that in the Kashiwa station. End standards of 100 mm length in the Kashiwa station are calibrated remotely within a standard deviation of 118 nm with the reference standards in the Tsuchiura station.
Strong Influence of Surface Structures on Enhanced Transmission through Subwavelength Hole Arrays
Authors: Ishihara Kunihiko , Ohashi Keishi
Published: September 2005

We analyzed the influence of the surface structure on enhanced transmission through subwavelength hole arrays. The hole arrays show extremely large enhanced transmission, but the transmission rapidly decreases as the hole diameter decreases. To clarify the cause of the transmission decrease, we calculated the dimple arrays and found that the diameter of the dimple strongly influences the efficiency of surface plasmon polaritons (SPPs) excitation. We show that the addition of the optimized surface structure to conventional hole arrays for the efficient SPP excitation leads to strongly enhanced transmission in much smaller diameter holes than the incident light wavelength.
Origin of Selective Growth of GaN on Maskless V-Grooved Sapphire Substrates by Metalorganic Chemical Vapor Deposition
Authors: Wang Jing , Guo Li Wei , Jia Hai Qiang , Xing Zhi Gang , Wang Yang , Chen Hong , Zhou Jun Ming
Published: September 2005

Selective growth of GaN on maskless V-grooved sapphire substrate is found by metalorganic chemical vapor deposition (MOCVD), where the V-grooved sapphire substrate is fabricated by chemical wet etching. GaN layers grow only on the (0001) mesas and no GaN growth occurs on the {110k} sidewalls of the V-grooves. The origin of the selective growth of GaN is unveiled and analyzed by energy dispersive X-ray (EDX) spectroscopy mapping. It is found that, Ga migration rates on the different facets are different clearly at high temperatures (HTs) so that the selective growth occurs. Contrary to the situation of HTs, GaN nucleates uniformly on the mesas and sidewalls at low temperatures (LTs) without selectivity. Thus, it is concluded that the selective growth of GaN on sapphire facets is a kinetic limited process. Accordingly, it is possible to fabricate GaN-based nanostructures by controlling the growth conditions.
Mechanically Stacked GaAs/GaInAsP Dual-Junction Solar Cell with High Conversion Efficiency of More than 31%
Authors: Yamada Takashi , Moto Akihiro , Iguchi Yasuhiro , Takahashi Mitsuo , Tanaka So , Tanabe Tatsuya , Takagishi Shigenori
Published: September 2005

We successfully fabricated high-performance GaAs and GaInAsP (band gap = 0.95 eV) single-junction solar cells with an area of 1×1 cm2. The conversion efficiencies of the GaAs and GaInAsP cells were 25.0 and 19.3%, respectively, under 1-sun air-mass 1.5 global (AM1.5G) conditions. The GaInAsP cell as the bottom cell under the mechanically stacked GaAs top cell also showed a high efficiency of 6.1%, and a total efficiency of 31.1% was achieved for the GaAs/GaInAsP tandem cell. This is the highest efficiency obtained under 1-sun AM1.5G conditions among the dual-junction cells ever reported.
Viewing Angle Enhancement of Three-Dimension/Two-Dimension Convertible Integral Imaging Display Using Double Collimated or Noncollimated Illumination
Authors: Park Jae-Hyeung , Kim Joohwan , Bae Jang-Pyo , Kim Yunhee , Lee Byoungho
Published: September 2005

Two schemes for enhancing the viewing angle of a three-dimension/two-dimension (3D/2D) convertible integral imaging display are proposed: The double collimated illumination scheme increases the horizontal viewing angle of the 3D images located anywhere in real and virtual fields. The diverging/converging illumination scheme selectively enhances both the horizontal and vertical viewing angles of 3D images located in one of either the real or virtual fields.
REVERSAL OF FORTUNE: The Resurgence of Individual Risk Assessment in Criminal Justice
Authors: Simon Jonathan
Published: September 2005

▪ Abstract  During the 1970s, the enterprise of individual risk assessment in the criminal justice system came under sharp attack from a number of angles, including legal, political, and empirical. A particularly acute site of this controversy was the use of psychological expertise to make individual risk assessments of persons with mental illness who found themselves within the criminal justice system. Successful court challenges to the procedures under which such persons were held in custody as dangerous were followed by empirical research on those persons released. The result was something of a paradigm crisis in the use of individual risk assessment in criminal justice and growing calls for its abandonment. By the 1990s, however, risk assessment was becoming more important than ever to the criminal justice system. This resurgence reflected the political demand for strategies to prevent violent crime and led to significant investments in research and policy development. In the new paradigm of risk assessment, psychological expertise is still valuable but mediated by actuarial and quasi-actuarial methods of identifying the dangerous.
Inhibition of glycogen synthase kinase-3β activity is sufficient to stimulate myogenic differentiation
Authors: van der Velden Jos L. J. , Langen Ramon C. J. , Kelders Marco C. J. M. , Wouters Emiel F. M. , Janssen-Heininger Yvonne M. W. , Schols Annemie M. W. J.
Published: September 2005

Skeletal muscle atrophy is a prominent and disabling feature of chronic wasting diseases. Prevention or reversal of muscle atrophy by administration of skeletal muscle growth (hypertrophy)-stimulating agents such as insulin-like growth factor I (IGF-I) could be an important therapeutic strategy in these diseases. To elucidate the IGF-I signal transduction responsible for muscle formation (myogenesis) during muscle growth and regeneration, we applied IGF-I to differentiating C2C12 myoblasts and evaluated the effects on phosphatidylinositol 3-kinase (PI3K)/Akt/glycogen synthase kinase-3β (GSK-3β) signaling and myogenesis. IGF-I caused phosphorylation and inactivation of GSK-3β activity via signaling through the PI3K/Akt pathway. We assessed whether pharmacological inhibition of GSK-3β with lithium chloride (LiCl) was sufficient to stimulate myogenesis. Addition of IGF-I or LiCl stimulated myogenesis, evidenced by increased myotube formation, muscle creatine kinase (MCK) activity, and troponin I (TnI) promoter transactivation during differentiation. Moreover, mRNAs encoding MyoD, Myf-5, myogenin, TnI-slow, TnI-fast, MCK, and myoglobin were upregulated in myoblasts differentiated in the presence of IGF-I or LiCl. Importantly, blockade of GSK-3β inhibition abrogated IGF-I- but not LiCl-dependent stimulation of myogenic mRNA accumulation, suggesting that the promyogenic effects of IGF-I require GSK-3β inactivation and revealing an important negative regulatory role for GSK-3β in myogenesis. Therefore, this study identifies GSK-3β as a potential target for pharmacological stimulation of muscle growth.
Interferon-γ activates transcription of NADPH oxidase 1 gene and upregulates production of superoxide anion by human large intestinal epithelial cells
Authors: Kuwano Yuki , Kawahara Tsukasa , Yamamoto Hironori , Teshima-Kondo Shigetada , Tominaga Kumiko , Masuda Kiyoshi , Kishi Kyoichi , Morita Kyoko , Rokutan Kazuhito
Published: September 2005

NADPH oxidase 1 (Nox1), a homolog of gp91 phox, is dominantly expressed in large intestinal epithelium, and reactive oxygen species derived from Nox1 are suggested to serve a role in host defense. We report that interferon (IFN)-γ, a crucial transactivator of the gp91 phox gene, also stimulates expression of Nox1 mRNA and protein in large intestinal epithelium (T84 cells), leading to fourfold upregulation of superoxide anion (O2−) generation. Introduction of small interfering Nox1 RNA completely blocked this priming. We cloned the region from −4,831 to +195 bp of the human Nox1 gene. To reveal IFN-γ-responsive cis elements, we performed transient expression assays using a reporter gene driven by serially truncated Nox1 promoters in T84 cells. IFN-γ-responsive elements were located between −4.3 and −2.6 kb, and one γ-activated sequence (GAS) element present at −3,818 to −3,810 bp exhibited this IFN-γ-dependent promoter activity. IFN-γ caused tyrosine phosphorylation of signal transducer and activator of transcription 1 (STAT1) and produced a protein-GAS complex that was recognized by anti-STAT1 antibody. The introduction of three-point mutation of GAS, which did not interact with STAT1, completely canceled the IFN-γ-dependent promoter activity of the region from −4,831 to +195 bp. A Janus protein tyrosine kinase 2 inhibitor (AG490) blocked the IFN-γ-stimulated tyrosine phosphorylation of STAT1, promoter activity of the −4,831 to +195 bp region, Nox1 mRNA expression, and O2− production, also suggesting a crucial role of STAT1 and GAS in the IFN-γ-stimulated transcription of the Nox1 gene. Our results support a potential contribution of Nox1 to mucosal host defense and inflammation in the colon.
Changes in intracellular electrolyte concentrations during apoptosis induced by UV irradiation of human myeloblastic cells
Authors: Arrebola F. , Fernández-Segura E. , Campos A. , Crespo P. V. , Skepper J. N. , Warley A.
Published: September 2005

Decreases in the intracellular concentrations of both K+ and Cl− have been implicated in playing a major role in the progression of apoptosis, but little is known about the temporal relationship between decreases in electrolyte concentration and the key events in apoptosis, and there is no information about how such decreases affect different intracellular compartments. Electron probe X-ray microanalysis was used to determine changes in element concentrations (Na, P, Cl, and K) in nucleus, cytoplasm, and mitochondria in U937 cells undergoing UV-induced apoptosis. In all compartments, the initial stages of apoptosis were characterized by decreases in [K] and [Cl]. The largest decreases in these elements were in the mitochondria and occurred before the release of cytochrome c. Initial decreases in [K] and [Cl] also preceded apoptotic changes in the nucleus. In the later stages of apoptosis, the [K] continued to decrease, whereas that of Cl began to increase toward control levels and was accompanied by an increase in [Na]. In the nucleus, these increases coincided with poly(ADP-ribose) polymerase cleavage, chromatin condensation, and DNA laddering. The cytoplasm was the compartment least affected and the pattern of change of Cl was similar to those in other compartments, but the decrease in [K] was not significant until after active caspase-3 was detected. Our results support the concept that normotonic cell shrinkage occurs early in apoptosis, and demonstrate that changes in the intracellular concentrations of K and Cl precede apoptotic changes in the cell compartments studied.
Response time and sensitivity of the ventilatory response to CO2 in unanesthetized intact dogs: central vs. peripheral chemoreceptors
Authors: Smith C. A. , Rodman J. R. , Chenuel B. J. A. , Henderson K. S. , Dempsey J. A.
Published: September 2005

We assessed the speed of the ventilatory response to square-wave changes in alveolar Pco2 and the relative gains of the steady-state ventilatory response to CO2 of the central chemoreceptors vs. the carotid body chemoreceptors in intact, unanesthetized dogs. We used extracorporeal perfusion of the reversibly isolated carotid sinus to maintain normal tonic activity of the carotid body chemoreceptor while preventing it from sensing systemic changes in CO2, thereby allowing us to determine the response of the central chemoreceptors alone. We found the following. 1) The ventilatory response of the central chemoreceptors alone is 11.2 (SD = 3.6) s slower than when carotid bodies are allowed to sense CO2 changes. 2) On average, the central chemoreceptors contribute ∼63% of the gain to steady-state increases in CO2. There was wide dog-to-dog variability in the relative contributions of central vs. carotid body chemoreceptors; the central exceeded the carotid body gain in four of six dogs, but in two dogs carotid body gain exceeded central CO2 gain. If humans respond similarly to dogs, we propose that the slower response of the central chemoreceptors vs. the carotid chemoreceptors prevents the central chemoreceptors from contributing significantly to ventilatory responses to rapid, transient changes in arterial Pco2 such as those after periods of hypoventilation or hyperventilation (“ventilatory undershoots or overshoots”) observed during sleep-disordered breathing. However, the greater average responsiveness of the central chemoreceptors to brain hypercapnia in the steady-state suggests that these receptors may contribute significantly to ventilatory overshoots once unstable/periodic breathing is fully established.
p53 Modulates RPA-Dependent and RPA-Independent WRN Helicase Activity
Authors: Sommers Joshua A. , Sharma Sudha , Doherty Kevin M. , Karmakar Parimal , Yang Qin , Kenny Mark K. , Harris Curtis C. , Brosh Robert M.
Published: September 2005

Werner syndrome is a hereditary disorder characterized by the early onset of age-related symptoms, including cancer. The absence of a p53-WRN helicase interaction may disrupt the signal to direct S-phase cells into apoptosis for programmed cell death and contribute to the pronounced genomic instability and cancer predisposition in Werner syndrome cells. Results from coimmunoprecipitation studies indicate that WRN is associated with replication protein A (RPA) and p53 in vivo before and after treatment with the replication inhibitor hydroxyurea or γ-irradiation that introduces DNA strand breaks. Analysis of the protein interactions among purified recombinant WRN, RPA, and p53 proteins indicate that all three protein pairs bind with similar affinity in the low nanomolar range. In vitro studies show that p53 inhibits RPA-stimulated WRN helicase activity on an 849-bp M13 partial duplex substrate. p53 also inhibited WRN unwinding of a short (19-bp) forked duplex substrate in the absence of RPA. WRN unwinding of the forked duplex substrate was specific, because helicase inhibition mediated by p53 was retained in the presence of excess competitor DNA and was significantly reduced or absent in helicase reactions catalyzed by a WRN helicase domain fragment lacking the p53 binding site or the human RECQ1 DNA helicase, respectively. p53 effectively inhibited WRN helicase activity on model DNA substrate intermediates of replication/repair, a 5′ ssDNA flap structure and a synthetic replication fork. Regulation of WRN helicase activity by p53 is likely to play an important role in genomic integrity surveillance, a vital function in the prevention of tumor progression.
[99mTcOAADT]-(CH2)2-NEt2: A Potential Small-Molecule Single-Photon Emission Computed Tomography Probe for Imaging Metastatic Melanoma
Authors: Cheng Zhen , Mahmood Ashfaq , Li Huazhi , Davison Alan , Jones Alun G.
Published: September 2005

Evaluation of [99mTc]oxotechnetium(V) complexes of the amine-amide-dithiol (AADT) chelates containing tertiary amine substituents as small-molecule probes for the diagnostic imaging of metastatic melanoma has shown that technetium-99m–labeled AADT-(CH2)2-NEt2 (99mTc-1) has the highest tumor uptake and other favorable biological properties. We have, therefore, assessed this agent in a more realistic metastatic melanoma model in which, after i.v. tail injection, a highly invasive melanoma cell line, B16F10, forms pulmonary tumor nodules in normal C57BL6 mice. Small melanotic lesions develop in the lungs and, on histologic examination, appear as small black melanoma colonies, increasing in size and number with time after tumor cell injection. Groups of mice received tumor cell inocula of 2 × 105, 4 × 105, or 8 × 105 B16F10 cells; 14 days later, 2 hours after 99mTc-1 administration, lung uptake of 2.83 ± 0.21%, 3.63 ± 1.07%, and 4.92 ± 1.61% injected dose per gram of tissue (% ID/g), respectively, was observed, compared with normal lung uptake of 2.13 ± 0.2% ID/g (P < 0.05). Additionally, a higher level of 99mTc-1 accumulation was seen 17 days after tumor cell inoculation as the lung lesions grew. These in vivo studies coupled with additional in vitro and ex vivo assessment show that 99mTc-1 has high and specific uptake in melanoma metastases in lungs and can potentially follow the temporal growth of these tumors.
The Growth Arrest Function of the Human Oncoprotein Mouse Double Minute-2 Is Disabled by Downstream Mutation in Cancer Cells
Authors: Zhou Ruizhe , Frum Rebecca , Deb Sumitra , Deb Swati P.
Published: September 2005

We have reported earlier that ectopic expression of mouse double minute-2 (MDM2) induces G1 arrest in normal cells. To explain occasional overexpression of MDM2 in cancer cells, we searched for deletion or substitution mutation in the growth suppressor domains of MDM2 in several breast cancer cell lines that overexpress the oncoprotein. Our results suggest the absence of alteration (deletion or substitution) in the open reading frame of MDM2 transcripts in such cells. Because the breast cancer cell line MCF-7 overexpresses MDM2, we isolated the full-length MDM2 transcript from this cell line. The MDM2 cDNA synthesized from transcripts isolated from MCF-7 cells induced inhibition of G1 to S phase transition in normal human diploid cells such as WI38, suggesting that the genetic alterations in breast cancer cells that overexpress MDM2 disable the growth arrest function of the oncoprotein. Consistently, overexpression of full-length MDM2 in MCF-7 cells over its high endogenous level did not inhibit G1-S transition efficiently. Although MDM2 overexpression was accompanied by CDK4 overexpression or absence of cdk4 inhibitor p16 in most breast cancer cells, we found remarkably high levels of cyclin A rather than cyclin E in these cells. Ectopic expression of cyclin A released MDM2-mediated inhibition of G1-S transition in normal human diploid WI38 cells. We propose that cancer cells expressing high levels of cyclin A escape MDM2-mediated G1 arrest, which may account for a selective growth advantage over normal cells.
Immortalization of Primary Human Prostate Epithelial Cells by c-Myc
Authors: Gil Jesús , Kerai Preeti , Lleonart Matilde , Bernard David , Cigudosa Juan Cruz , Peters Gordon , Carnero Amancio , Beach David
Published: September 2005

A significant percentage of prostate tumors have amplifications of the c-Myc gene, but the precise role of c-Myc in prostate cancer is not fully understood. Immortalization of human epithelial cells involves both inactivation of the Rb/p16INK4a pathway and telomere maintenance, and it has been recapitulated in culture by expression of the catalytic subunit of telomerase, hTERT, in combination with viral oncoproteins. Here, we show the immortalization of human prostate epithelial cells (HPrEC) by a single genetic event, the expression of the c-Myc oncogene. Myc stabilizes telomere length in HPrEC through up-regulation of hTERT expression and overrides the accumulation of cell cycle inhibitory proteins, such as p16INK4a. Overall, HPrECs expressing c-Myc retain many characteristics of normal cells, such as the induction of a senescence-like growth arrest in response to oncogenic Ras, an intact p53 response, and an absence of gross karyotypic abnormalities. However, HPrECs expressing c-Myc lack a Rb/p16INK4a checkpoint and can be transformed without the need for additional genetic lesions in that pathway. These results give a partial explanation for the physiologic role of c-Myc overexpression in prostate cancer.
Primary Cutaneous T-Cell Lymphomas Show a Deletion or Translocation Affecting NAV3, the Human UNC-53 Homologue
Authors: Karenko Leena , Hahtola Sonja , Päivinen Suvi , Karhu Ritva , Syrjä Sanna , Kähkönen Marketta , Nedoszytko Boguslaw , Kytölä Soili , Zhou Ying , Blazevic Vesna , Pesonen Maria , Nevala Hanna , Nupponen Nina , Sihto Harri , Krebs Inge , Poustka Annemarie , Roszkiewicz Jadwiga , Saksela Kalle , Peterson Pärt , Visakorpi Tapio , Ranki Annamari
Published: September 2005

Multicolor fluorescent in situ hybridization (FISH) was used to identify acquired chromosomal aberrations in 12 patients with mycosis fungoides or Sézary syndrome, the most common forms of primary cutaneous T-cell lymphoma (CTCL). The most frequently affected chromosome was 12, which showed clonal deletions or translocations with a break point in 12q21 or 12q22 in five of seven consecutive Sézary syndrome patients and a clonal monosomy in the sixth patient. The break point of a balanced translocation t(12;18)(q21;q21.2), mapped in the minimal common region of two deletions, fine mapped to 12q2. By locus-specific FISH, the translocation disrupted one gene, NAV3 (POMFIL1), a human homologue of unc-53 in Caenorhabditis elegans. A missense mutation in the remaining NAV3 allele was found in one of six cases with a deletion or translocation. With locus-specific FISH, NAV3 deletions were found in the skin lesions of four of eight (50%) patients with early mycosis fungoides (stages IA-IIA) and in the skin or lymph node of 11 of 13 (85%) patients with advanced mycosis fungoides or Sézary syndrome. Preliminary functional studies with lentiviral small interfering RNA-based NAV3 silencing in Jurkat cells and in primary lymphocytes showed enhanced interleukin 2 expression (but not CD25 expression). Thus, NAV3 may contribute to the growth, differentiation, and apoptosis of CTCL cells as well as to the skewing from Th1-type to Th2-type phenotype during disease progression. NAV3, a novel putative haploinsufficient tumor suppressor gene, is disrupted in most cases of the commonest types of CTCL and may thus provide a new diagnostic tool.
Mitotic Arrest Deficient 2 Expression Induces Chemosensitization to a DNA-Damaging Agent, Cisplatin, in Nasopharyngeal Carcinoma Cells
Authors: Cheung Hiu Wing , Jin Dong-Yan , Ling Ming-tat , Wong Yong Chuan , Wang Qi , Tsao Sai Wah , Wang Xianghong
Published: September 2005

Recently, mitotic arrest deficient 2 (MAD2)–mediated spindle checkpoint is shown to induce mitotic arrest in response to DNA damage, indicating overlapping roles of the spindle checkpoint and DNA damage checkpoint. In this study, we investigated if MAD2 played a part in cellular sensitivity to DNA-damaging agents, especially cisplatin, and whether it was regulated through mitotic checkpoint. Using nine nasopharyngeal carcinoma (NPC) cell lines, we found that decreased MAD2 expression was correlated with cellular resistance to cisplatin compared with the cell lines with high levels of MAD2. Exogenous MAD2 expression in NPC cells also conferred sensitivity to DNA-damaging agents especially cisplatin but not other anticancer drugs with different mechanisms of action. The increased cisplatin sensitivity in MAD2 transfectants was associated with mitotic arrest and activation of apoptosis pathway evidenced by the increased mitotic index and apoptosis rate as well as decreased Bcl-2 and Bax ratio and expression of cleaved poly(ADP-ribose) polymerase and caspase 3. Our results indicate that the MAD2-induced chemosensitization to cisplatin in NPC cells is mediated through the induction of mitotic arrest, which in turn activates the apoptosis pathway. Our evidence further confirms the previous hypothesis that spindle checkpoint plays an important part in DNA damage-induced cell cycle arrest and suggests a novel role of MAD2 in cellular sensitivity to cisplatin.
Induction of Apoptosis in Primary Meningioma Cultures by Fenretinide
Authors: Puduvalli Vinay K. , Li Jessica T. , Chen Ling , McCutcheon Ian E.
Published: September 2005

Fenretinide, a synthetic retinoid that induces apoptosis in tumor cells in vitro, is being evaluated in clinical trials as a chemotherapeutic agent against several malignancies. Due to its ease of administration, long-term tolerability, and low incidence of long-term side effects, we explored its potential as a therapeutic agent against meningiomas by examining its efficacy in vitro against such cells in primary culture. Cells, cultured from freshly resected benign, atypical, or malignant meningiomas, were exposed to fenretinide (10 μmol/L). Treatment effects were assessed using flow cytometry, Western blot analysis, semiquantitative reverse transcription-PCR for retinoid receptor expression, and changes in insulin-like growth factor-I (IGF-I)–induced proliferation. Fenretinide induced apoptosis in the three grades of meningioma primary cells tested, as shown by the appearance of a sub-G1 fraction in flow cytometric analysis and by the detection of poly-adenosyl ribonucleotidyl phosphorylase cleavage indicating caspase activation. Fenretinide treatment also increased levels of the death receptor DR5 and caused mitochondrial membrane depolarization. The levels of the retinoid receptors, retinoic acid receptor α and retinoid X receptor γ, were up-regulated in response to fenretinide, suggestive of ligand-induced receptor up-regulation. IGF-I-induced proliferation in the meningioma cells was abolished by fenretinide. We conclude that fenretinide induces apoptosis in all three histologic subtypes of meningioma and exerts diverse cellular effects, including DR5 up-regulation, modulation of retinoid receptor levels, and inhibition of IGF-I-induced proliferation. These results provide preliminary evidence that fenretinide has activity against meningiomas and suggest that further studies are warranted to explore its potential as a therapeutic agent against meningiomas.
CXCL-12/Stromal Cell–Derived Factor-1α Transactivates HER2-neu in Breast Cancer Cells by a Novel Pathway Involving Src Kinase Activation
Authors: Cabioglu Neslihan , Summy Justin , Miller Claudia , Parikh Nila U. , Sahin Aysegul A. , Tuzlali Sitki , Pumiglia Kevin , Gallick Gary E. , Price Janet E.
Published: September 2005

Experimental evidence suggests that CXCR4, a Gi protein–coupled receptor for the ligand CXCL12/stromal cell–derived factor-1α (SDF-1α), plays a role in breast cancer metastasis. Transactivation of HER2-neu by G protein–coupled receptor activation has been reported as a ligand-independent mechanism of activating tyrosine kinase receptors. We found that SDF-1α transactivated HER2-neu in the breast cancer cell lines MDA-MB-361 and SKBR3, which express both CXCR4 and HER2-neu. AMD3100, a CXCR4 inhibitor, PKI 166, an epidermal growth factor receptor/HER2-neu tyrosine kinase inhibitor, and PP2, a Src kinase inhibitor, each blocked SDF-1α–induced HER2-neu phosphorylation. Blocking Src kinase, with PP2 or using a kinase-inactive Src construct, and inhibiting epidermal growth factor receptor/HER2-neu signaling with PKI 166 each inhibited SDF-1α–stimulated cell migration. We report a novel mechanism of HER2-neu transactivation through SDF-1α stimulation of CXCR4 that involves Src kinase activation.
Expression of the Carcinoembryonic Antigen Gene Is Inhibited by SOX9 in Human Colon Carcinoma Cells
Authors: Jay Philippe , Berta Philippe , Blache Philippe
Published: September 2005

The human carcinoembryonic antigen (CEA) is overexpressed in many types of human cancers and is commonly used as a clinical marker. In colon cancer, this overexpression protects cells against apoptosis and contributes to carcinogenesis. Therefore, CEA-expressing cells as well as CEA expression itself constitute potential therapeutic targets. In this report, we show that the transcription factor SOX9 down-regulates CEA gene expression and, as a probable consequence, induces apoptosis in the human colon carcinoma cell line HT29Cl.16E.
Antisense-Mediated Suppression of Hyaluronan Synthase 2 Inhibits the Tumorigenesis and Progression of Breast Cancer
Authors: Udabage Lishanthi , Brownlee Gary R. , Waltham Mark , Blick Tony , Walker Emma C. , Heldin Paraskevi , Nilsson Susan K. , Thompson Erik W. , Brown Tracey J.
Published: September 2005

The progression of several cancers is correlated with the increased synthesis of the glycosaminoglycan, hyaluronan. Hyaluronan is synthesized at the plasma membrane by various isoforms of hyaluronan synthases (HAS). The importance of HAS2 expression in highly invasive breast cancer was characterized by the antisense inhibition of HAS2 (ASHAS2). The effect of HAS2 inhibition on cell proliferation, migration, hyaluronan metabolism, and receptor status was characterized in vitro, whereas the effect on tumorigenicity and metastasis was established in vivo. HAS2 inhibition resulted in a 24-hour lag in proliferation that was concomitant to transient arrest of 79% of the cell population in G0-G1. Inhibition of HAS2 did not alter the expression of the other HAS isoforms, whereas hyaluronidase (HYAL2) and the hyaluronan receptor, CD44, were significantly down-regulated. ASHAS2 cells accumulated greater amounts of high molecular weight hyaluronan (>10,000 kDa) in the culture medium, whereas mock and parental cells liberated less hyaluronan of three distinct molecular weights (100, 400, and 3,000 kDa). The inhibition of HAS2 in the highly invasive MDA-MB-231 breast cancer cell line inhibited the initiation and progression of primary and secondary tumor formation following s.c. and intracardiac inoculation into nude mice, whereas controls readily established both primary and secondary tumors. The lack of primary and secondary tumor formation was manifested by increased survival times where ASHAS2 animals survived 172% longer than the control animals. Collectively, these unique results strongly implicate the central role of HAS2 in the initiation and progression of breast cancer, potentially highlighting the codependency between HAS2, CD44, and HYAL2 expression.
Thiazolidenediones Mediate Apoptosis in Prostate Cancer Cells in Part through Inhibition of Bcl-xL/Bcl-2 Functions Independently of PPARγ
Authors: Shiau Chung-Wai , Yang Chih-Cheng , Kulp Samuel K. , Chen Kuen-Feng , Chen Chang-Shi , Huang Jui-Wen , Chen Ching-Shih
Published: September 2005

Certain members of the thiazolidenedione family of the peroxisome proliferator-activated receptor γ (PPARγ) agonists, such as troglitazone and ciglitazone, exhibit antitumor effects; however, the underlying mechanism remains inconclusive. This study shows that the effect of these thiazolidenedione members on apoptosis in prostate cancer cells is independent of PPARγ activation. First, close structural analogues of thiazolidenediones, whereas devoid of PPARγ activity, retain the ability to induce apoptosis with equal potency. Second, both PC-3 (PPARγ-expressing) and LNCaP (PPARγ-deficient) cells are sensitive to apoptosis induction by troglitazone and its PPARγ-inactive analogue irrespective of their PPARγ expression status. Third, rosiglitazone and pioglitazone, potent PPARγ agonists, show marginal effects on apoptosis even at high concentrations. Evidence indicates that the apoptotic effect of troglitazone, ciglitazone, and their PPARγ-inactive analogues 5-[4-(6-hydroxy-2,5,7,8-tetramethyl-chroman-2-ylmethoxy)-benzylidene]-2,4-thiazolidine-dione (Δ2-TG) and 5-[4-(1-methyl-cyclohexylmethoxy)-benzylidene]-thiazolidine-2,4-dione, respectively, is in part attributable to their ability to inhibit the anti-apoptotic functions of Bcl-xL and Bcl-2. Treatment of PC-3 cells with troglitazone or Δ2-TG led to reduced association of Bcl-2 and Bcl-xL with Bak, leading to caspase-dependent apoptosis. Bcl-xL overexpression protects LNCaP cells from apoptosis induction by troglitazone and Δ2-TG in an expression level–dependent manner. Considering the pivotal role of Bcl-xL/Bcl-2 in regulating mitochondrial integrity, this new mode of mechanism provides a framework to account for the PPARγ-independent action of thiazolidenediones in inducing apoptosis in cancer cells. Moreover, dissociation of these two pharmacologic activities provides a molecular basis to develop novel Bcl-xL/Bcl-2 inhibitors, of which the proof of principle is illustrated by a Δ2-TG analogue with potent in vivo antitumor activities.
PUMA Overexpression Induces Reactive Oxygen Species Generation and Proteasome-Mediated Stathmin Degradation in Colorectal Cancer Cells
Authors: Liu Zhihe , Lu Huimei , Shi Honglian , Du Yuchun , Yu Jian , Gu Sheng , Chen Xian , Liu Ke Jian , Hu Chien-an A.
Published: September 2005

Increased amounts of reactive oxygen species (ROS) induce apoptosis in mammalian cells. PUMA (P53 up-regulated modulator of apoptosis), a mitochondrial proapoptotic BH3-only protein, induces rapid apoptosis through a Bax- and mitochondria-dependent pathway. However, the molecular basis of PUMA-induced apoptosis is largely not understood. Using a combination of biophysical and biochemical methods and PUMA-inducible colorectal cells, DLD-1.PUMA, we showed that (a) PUMA-induced apoptosis is dose and time dependent; (b) PUMA-induced apoptosis is directly associated with ROS generation; (c) diphenyleneiodonium chloride, a ROS blocker, or BAX-inhibiting peptide, a suppressor of BAX translocation, decreased ROS generation and apoptosis in DLD-1.PUMA cells; (d) overexpression of PUMA induced up-regulation (>1.34-fold) of peroxiredoxin 1 and down-regulation (by 25%) of stathmin through proteasome-mediated degradation; and (e) hydrogen peroxide down-regulated stathmin and disrupted the cellular microtubule network. Our findings indicate that PUMA induces apoptosis, in part, through the BAX-dependent generation of superoxide and hydrogen peroxide. ROS overproduction and oxidative stress induce proteome-wise alterations, such as stathmin degradation and disorganization of the cell microtubule network, in apoptotic cells.
Androgens Up-regulate the Insulin-like Growth Factor-I Receptor in Prostate Cancer Cells
Authors: Pandini Giuseppe , Mineo Rossana , Frasca Francesco , Roberts Charles T. , Marcelli Marco , Vigneri Riccardo , Belfiore Antonino
Published: September 2005

In this study, we show that androgens up-regulate insulin-like growth factor-I receptor (IGF-IR) expression and sensitize prostate cancer cells to the biological effects of IGF-I. Both dihydrotestosterone and the synthetic androgen R1881 induced an ∼6-fold increase in IGF-IR expression in androgen receptor (AR)–positive prostate cancer cells LNCaP. In accordance with IGF-IR up-regulation, treatment with the nonmetabolizable androgen R1881 sensitized LNCaP cells to the mitogenic and motogenic effects of IGF-I, whereas an IGF-IR blocking antibody effectively inhibited these effects. By contrast, these androgens did not affect IGF-IR expression in AR-negative prostate cancer cells PC-3. Reintroduction of AR into PC-3 cells by stable transfection restored the androgen effect on IGF-IR up-regulation. R1881-induced IGF-IR up-regulation was partially inhibited by the AR antagonist Casodex (bicalutamide). Two other AR antagonists, cyproterone acetate and OH-flutamide, were much less effective. Androgen-induced IGF-IR up-regulation was not dependent on AR genomic activity, because two AR mutants, AR-C619Y and AR-C574R, devoid of DNA binding activity and transcriptional activity were still able to elicit IGF-IR up-regulation in HEK293 kidney cells in response to androgens. Moreover, androgen-induced IGF-IR up-regulation involves the activation of the Src-extracellular signal-regulated kinase pathway, because it was inhibited by both the Src inhibitor PP2 and the MEK-1 inhibitor PD98059. The present observations strongly suggest that AR activation may stimulate prostate cancer progression through the altered IGF-IR expression and IGF action. Anti-androgen therapy may be only partially effective, or almost ineffective, in blocking important biological effects of androgens, such as activation of the IGF system.
Dipeptidyl Peptidase Inhibits Malignant Phenotype of Prostate Cancer Cells by Blocking Basic Fibroblast Growth Factor Signaling Pathway
Authors: Wesley Umadevi V. , McGroarty Michelle , Homoyouni Asal
Published: September 2005

Dipeptidyl peptidase IV (DPPIV) is a serine protease with tumor suppressor function. It regulates the activities of mitogenic peptides implied in cancer development. Progression of benign prostate cancer to malignant metastasis is linked to increased production of basic fibroblast growth factor (bFGF), a powerful mitogen. In this study, using in vitro model system we show that DPPIV loss is associated with increased bFGF production in metastatic prostate cancer cells. DPPIV reexpression in prostate cancer cells blocks nuclear localization of bFGF, reduces bFGF levels, inhibits mitogen-activated protein kinase (MAPK)-extracellular signal-regulated kinase (ERK)1/2 activation, and decreases levels of urokinase-type plasminogen activator, known downstream effectors of bFGF signaling pathway. These molecular changes were accompanied by induction of apoptosis, cell cycle arrest, inhibition of in vitro cell migration, and invasion. Silencing of DPPIV by small interfering RNA resulted in increased bFGF levels and restoration of mitogen-activated protein kinase (MAPK)-extracellular signal-regulated kinase (ERK)1/2 activation. These results indicate that DPPIV inhibits the malignant phenotype of prostate cancer cells by blocking bFGF signaling pathway.
Expression of Notch-1 and Its Ligands, Delta-Like-1 and Jagged-1, Is Critical for Glioma Cell Survival and Proliferation
Authors: Purow Benjamin W. , Haque Raqeeb M. , Noel Martha W. , Su Qin , Burdick Michael J. , Lee Jeongwu , Sundaresan Tilak , Pastorino Sandra , Park John K. , Mikolaenko Irina , Maric Dragan , Eberhart Charles G. , Fine Howard A.
Published: September 2005

The Notch family of proteins plays an integral role in determining cell fates, such as proliferation, differentiation, and apoptosis. We show that Notch-1 and its ligands, Delta-like-1 and Jagged-1, are overexpressed in many glioma cell lines and primary human gliomas. Immunohistochemistry of a primary human glioma tissue array shows the presence in the nucleus of the Notch-1 intracellular domain, indicating Notch-1 activation in situ. Down-regulation of Notch-1, Delta-like-1, or Jagged-1 by RNA interference induces apoptosis and inhibits proliferation in multiple glioma cell lines. In addition, pretreatment of glioma cells with Notch-1 or Delta-like-1 small interfering RNA significantly prolongs survival in a murine orthotopic brain tumor model. These results show, for the first time, the dependence of cancer cells on a single Notch ligand; they also suggest a potential Notch juxtacrine/autocrine loop in gliomas. Notch-1 and its ligands may present novel therapeutic targets in the treatment of glioma.
Angiogenin Is Translocated to the Nucleus of HeLa Cells and Is Involved in Ribosomal RNA Transcription and Cell Proliferation
Authors: Tsuji Takanori , Sun Yeqing , Kishimoto Koji , Olson Karen A. , Liu Shumei , Hirukawa Saori , Hu Guo-fu
Published: September 2005

Angiogenin is an angiogenic protein known to play a role in rRNA transcription in endothelial cells. Nuclear translocation of angiogenin in endothelial cells decreases as cell density increases and ceases when cells are confluent. Here we report that angiogenin is constantly translocated to the nucleus of HeLa cells in a cell density–independent manner. Down-regulation of angiogenin expression by antisense and RNA interference results in a decrease in rRNA transcription, ribosome biogenesis, proliferation, and tumorigenesis both in vitro and in vivo. Exogenous angiogenin rescues the cells from antisense and RNA interference inhibition. The results showed that angiogenin is constitutively translocated into the nucleus of HeLa cells where it stimulates rRNA transcription. Thus, besides its angiogenic activity, angiogenin also plays a role in cancer cell proliferation.
Small Interfering RNA–Mediated Polo-Like Kinase 1 Depletion Preferentially Reduces the Survival of p53-Defective, Oncogenic Transformed Cells and Inhibits Tumor Growth in Animals
Authors: Guan Ran , Tapang Paul , Leverson Joel D. , Albert Daniel , Giranda Vincent L. , Luo Yan
Published: September 2005

Polo-like kinase 1 (Plk1) is required for multiple stages of mitosis and is up-regulated in many human malignancies. We depleted Plk1 expression using small interfering RNA (siRNA) and showed defects in bipolar spindle formation and cytokinesis, growth inhibition, and apoptosis induction in human cancer cell lines. To our surprise, depletion of Plk1 in normal human cells did not result in obvious cell cycle defects, and did not induce significant inhibition of cell growth for at least two cell cycles. In addition, Plk1 siRNA inhibited colony formation in soft agar and tumorigenesis in a HT1080 xenograft model in a dose-dependent manner. Analysis with isogenic pairs of cell lines, differing in p53 status, revealed that Plk1 depletion preferentially induced mitotic arrest, aneuploidy, and reduced cell survival in the p53-defective cell lines. No obvious defects were observed in most p53 wild-type cells during the first few cell cycles. In addition, long-term survival studies revealed that p53 facilitates survival upon Plk1 depletion. Therefore, short-term inhibition of Plk1 can kill tumor cells while allowing normal cells to survive. These data validate the episodic inhibition of Plk1 as a very useful approach for cancer treatment.
Regulation of DNA Methyltransferase 1 by the pRb/E2F1 Pathway
Authors: McCabe Michael T. , Davis Joanne N. , Day Mark L.
Published: September 2005

Tumor suppressor gene silencing by DNA hypermethylation contributes to tumorigenesis in many tumor types. This aberrant methylation may be due to increased expression and activity of DNA methyltransferases, which catalyze the transfer of methyl groups from S-adenosylmethionine to cytosines in CpG dinucleotides. Elevated expression of the maintenance DNA methyltransferase, DNA methyltransferase 1 (DNMT-1), has been shown in carcinomas of the colon, lung, liver, and prostate. Based on the nearly ubiquitous alterations of both DNA methylation and the retinoblastoma protein (pRb) pathway found in human cancer, we investigated a potential regulatory pathway linking the two alterations in murine and human prostate epithelial cells. Analysis of DNA methyltransferase levels in Rb−/− murine prostate epithelial cell lines revealed elevated Dnmt-1 levels. Genomic DNA sequence analysis identified conserved E2F consensus binding sites in proximity to the transcription initiation points of murine and human Dnmt-1. Furthermore, the Dnmt-1 promoter was shown to be regulated by the pRb/E2F pathway in murine and human cell lines of epithelial and fibroblast origin. In the absence of pRb, Dnmt-1 transcripts exhibited aberrant cell cycle regulation and Rb−/− cells showed aberrant methylation of the paternally expressed gene 3 (Peg3) tumor suppressor gene. These findings show a link between inactivation of the pRb pathway and induction of DNA hypermethylation of CpG island–containing genes in tumorigenesis.
Tachyplesin Activates the Classic Complement Pathway to Kill Tumor Cells
Authors: Chen Jinguo , Xu Xue-Ming , Underhill Charles B. , Yang Shanmin , Wang Luping , Chen Yixin , Hong Shuigen , Creswell Karen , Zhang Lurong
Published: September 2005

Tachyplesin is a small, cationic peptide that possesses antitumor properties. However, little is known about its action mechanism. We used phage display to identify a protein that interacted with tachyplesin and isolated a sequence corresponding to the collagen-like domain of C1q, a key component in the complement pathway. Their interaction was subsequently confirmed by both ELISA and affinity precipitation. Tachyplesin seemed to activate the classic complement cascade because it triggered several downstream events, including the cleavage and deposition of C4 and C3 and the formation of C5b-9. When TSU tumor cells were treated with tachyplesin in the presence of serum, activated C4b and C3b could be detected on tumor cells by flow cytometry, Western blotting, and confocal microscopy. However, this effect was blocked when the tumor cells were treated with hyaluronidase or a large excess of hyaluronan, indicating that hyaluronan or related glycosaminoglycans were involved in this process. Treatment of cells with tachyplesin and serum increased in membrane permeability as indicated by the ability of FITC-dextran to enter the cytoplasm. Finally, the combination of tachyplesin and human serum markedly inhibited the proliferation and caused death of TSU cells, and these effects were attenuated if the serum was heat-inactivated or if hyaluronidase was added. Taken together, these observations suggest that tachyplesin binds to both hyaluronan on the cell surface and C1q in the serum and activates the classic complement cascade, which damages the integrity of the membranes of the tumor cells resulting in their death.
Development of Magnetic Resonance Imaging Contrast Material for In vivo Mapping of Tissue Transglutaminase Activity
Authors: Mazooz Galit , Mehlman Tevie , Lai Thung-Shen , Greenberg Charles S. , Dewhirst Mark W. , Neeman Michal
Published: September 2005

Transglutaminases are a family of enzymes that play an important role in tissue remodeling by catalyzing covalent cross-links between proteins of the extracellular matrix. Elevated activity of transglutaminase was shown at the boundaries of invading tumors, in association with angiogenesis, in stabilization of atherosclerotic plaques, and in generation of blood clots. The aim of this work was to develop a low molecular weight substrate of transglutaminase that could serve for noninvasive magnetic resonance and optical mapping of transglutaminase-mediated cross-linking activity. A 2 kDa contrast material was generated which showed cross-linking by either tissue transglutaminase or factor XIII in the context of multicellular tumor spheroids or fibrin clots, respectively. Successful detection by nuclear magnetic resonance microscopy of transglutaminase-mediated cross-linking of the contrast material to MCF7 multicellular spheroids provides hope that this approach could potentially be developed for clinical demarcation of sites of transglutaminase activity.