bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of decontamination and implant surface characteristics on re‐osseointegration following treatment of peri‐implantitis
Authors: Parlar Ateş , Bosshardt Dieter D. , Çetiner Deniz , Schafroth Denis , Ünsal Berrin , Haytaç Cenk , Lang Niklaus P.
Published: March 2009

Background: Although considerable bone fill may occur following treatment of peri‐implantitis, re‐osseointegration appears to be limited and unpredictable.

Objectives: To evaluate the effects of various decontamination techniques and implant surface configurations on re‐osseointegration of contaminated dental implants.

Material and methods: Three months after tooth extraction, implants consisting of a basal part and an exchangeable intraosseous implant cylinder (EIIC) were placed in the mandibles of dogs. The EIIC was machined (M), sandblasted and acid‐etched (SLA), or titanium plasma sprayed (TPS). Ligature‐induced peri‐implantitis was initiated 8 weeks post‐implantation and lasted until bone loss reached the junction of the two implant parts. Three treatment modalities were applied: (T1) the EIIC was exchanged for a pristine EIIC; (T2) the EIIC was sprayed in situ with saline; and (T3) the EIIC was removed, cleansed outside the mouth by spraying with saline, steam‐sterilized, and remounted. A collagen barrier was placed over each fixture, and 3 months later, samples were processed for histology and histomorphometry.

Results: T2 revealed the highest bone‐to‐implant contact (BIC) level (significantly better than T1 and T3). T2 also yielded the highest bone crest level (significantly better than T1), followed by T3 (significantly better than T1). SLA showed the highest BIC level (significantly better than M), followed by TPS. There were no statistically significant differences in bone crest height between implant types.

Conclusions: Both SLA implants and in situ cleansing resulted in the best re‐osseointegration and bone fill of previously contaminated implants.
Histometric evaluation of bone around titanium implants with different surface treatments in rats exposed to cigarette smoke inhalation
Authors: Correa Mônica G. , Gomes Campos Mirella L. , César‐Neto João B. , Casati Marcio Z. , Nociti Francisco H. , Sallum Enilson A.
Published: March 2009

Objectives: There is a lack of histological information about the influence of cigarette smoke on bone around surface‐treated implants. The aim of the present study was to test the influence of titanium surface treatment on osseointegration in animals that were exposed to intermittent cigarette smoke inhalation.

Material and methods: Twenty‐two male Wistar rats were used. One tibia, chosen at random, received a machined titanium implant (MI) while the other received an aluminum oxide‐blasted surface implant (ABI). The animals were randomly assigned to one of the following groups: Group 1 – control (n=11) and Group 2 – intermittent cigarette smoke inhalation (n=11). Sixty days after surgery, the animals were sacrificed. The degree of bone‐to‐implant contact (BIC), bone filling (BF) within the limits of the threads of the implants and bone density (proportion of mineralized bone in a 500‐μm‐wide zone lateral to the implant – BD) were measured in the cortical (zone A) and cancellous bone (zone B) areas.

Results: Data analysis showed significant differences when comparing the groups and implant surfaces in both zones for BIC (two‐way ANOVA –P<0.05). The two groups presented higher BIC mean values for ABI, when compared with MI (P<0.05). In group 2, cigarette smoke inhalation negatively affected BF in both zones (P<0.05). Group 2 presented a significantly decreased BD in both zones (P<0.05). No statistically significant differences were observed between surfaces in any of the groups for BD.

Conclusion: Within the limits of the present study, it can be concluded that the aluminum oxide blast surface treatment may increase the degree of BIC but cannot overcome the detrimental effect of tobacco smoke on bone around titanium implants.
Osteotome sinus floor elevation technique without grafting material: 3‐year results of a prospective pilot study
Authors: Nedir Rabah , Bischof Mark , Vazquez Lydia , Nurdin Nathalie , Szmukler‐Moncler Serge , Bernard Jean‐Pierre
Published: March 2009

Objective: In a prospective pilot study, short≤10 mm ITI‐SLA implants were placed in the resorbed posterior maxilla by means of an osteotome sinus floor elevation (OSFE) procedure without grafting material. This paper presents 3‐year data assessing bone‐level changes around implants.

Material and methods: Twenty‐five implants were placed in 17 patients to rehabilitate 16 molar and nine premolar sites. The mean residual bone height (RBH) was 5.4 ± 2.3 mm. A healing period of 3–4 months was allowed before abutment tightening. Most implants (21/25) were 10 mm long, and the others were 8 and 6 mm long. At the 3‐year control, endo‐sinus bone gain, implant length protruding into the sinus and crestal bone loss (CBL) were measured on periapical radiographs.

Results: All implants fulfilled the survival criteria. Despite the absence of grafting material, implants were embedded into newly formed bone tissue. All implants gained endo‐sinus bone; the mean gained bone was 3.1 ± 1.5 mm. The residual protrusion length decreased from 4.9 ± 2.1 to 1.8 ± 2.1 mm. CBL was 0.9 ± 0.8 mm.

Conclusions: This study confirms that the OSFE procedure without grafting material is sufficient to create bone beyond the natural limit of the sinus. On the mid‐term of 3 years, the technique was found to be predictable in the posterior maxilla when the RBH is limited. Implants gained endo‐sinus bone despite the lack of grafting material. Bone gain was still improving over the first‐year control. No shrinkage of the augmented area was observed.
The role of cytokines in the initiation, expansion, and control of cellular immunity to tuberculosis
Authors: Cooper Andrea M. , Khader Shabaana A.
Published: March 2009

Summary: Tuberculosis (TB) results from an interaction between a potent immune response and a chronically persistent pathogen. The ability of Mycobacterium tuberculosis (Mtb) to induce a strong immune response while being able to resist the ability of the host to clear bacteria provides an excellent tool with which to investigate the role of specific cytokine pathways on the induction, expansion, and control of the effector T‐cell response. In this review, the role of interleukin‐12p40 (IL‐12p40), IL‐12p70, IL‐23, and IL‐27 in the immune response to Mtb are described. We show that IL‐12(p40)2 acts to mediate the activation of dendritic cells to become responsive to homeostatic chemokines. We also show that IL‐12p70 is required for the optimal interferon‐γ (IFN‐γ) T‐cell response, which is required for control of Mtb growth. IL‐23 can induce IFN‐γ responses in the lung if IL‐12 is not present, but its major role is in supporting the IL‐17 response within the lung. Neither IL‐23 nor IL‐17 is required for early control of Mtb in the lung. IL‐23 and IL‐17, however, can be instrumental in vaccine‐induced protection. Finally, IL‐27 limits protective immunity in the lung, but it is also required for long‐term survival. These cytokines are therefore key players in the immune response to TB.
Th17 cytokines and mucosal immunity
Authors: Dubin Patricia J. , Kolls Jay K.
Published: March 2009

Summary: The T‐helper 17 (Th17) lineage is a recently described subset of memory T cells that is characterized by its CD4+ status and its ability to make a constellation of cytokines including interleukin‐17A (IL‐17A), IL‐17F, IL‐22, and, in humans, IL‐26. Although most extensively described in the autoimmunity literature, there is growing evidence that the Th17 lineage plays a significant role in mediating host mucosal immunity to a number of pulmonary pathogens. This review highlights our current understanding of the role of the Th17 lineage and Th17 cytokines in mediating mucosal immunity to both pulmonary and gastrointestinal pathogens. While we have the strongest evidence that the Th17 lineage is centrally involved in mediating the host response to Gram‐negative extracellular pulmonary pathogens, this literature is rapidly evolving and demonstrates a central role for Th17 cytokines both in primary infection and in recall responses seen in vaccine studies. In this review, we summarize the current state of this literature and present possible applications of Th17‐targeted immunotherapy in the treatment and prevention of infection.
Th17 cytokines and their emerging roles in inflammation and autoimmunity
Authors: Fouser Lynette A. , Wright Jill F. , Dunussi‐Joannopoulos Kyriaki , Collins Mary
Published: March 2009

Summary: T‐helper 17 (Th17) cells are a new lineage of CD4+ T cells that are characterized by their production of interleukin‐17A (IL‐17A). Recent studies show that these cells can also express IL‐17F, IL‐22, and IL‐21. IL‐17A and IL‐17F can form a heterodimeric cytokine, which mediates biological activities, at least in part, through shared receptors with IL‐17A and IL‐17F homodimers. The cytokines made by Th17 cells represent three distinct gene families, highlighting the unique biology of these cells. Accumulating data support a role for Th17 cells and these cytokines in inflammatory processes and in animal models of autoimmunity or inflammation. Emerging data in clinical trials support our understanding of the importance of Th17 cells in inflammatory disease. Future clinical studies will allow us to evaluate the role of each cytokine independently in contributing to human diseases with immune‐mediated pathologies and to design optimal cytokine‐targeted therapies for these diseases.
Investigations of Free Anthraquinones from Rhubarb Against α‐Naphthylisothiocyanate‐induced Cholestatic Liver Injury in Rats
Authors: Zhao Yan‐Ling , Wang Jia‐Bo , Zhou Guang‐De , Shan Li‐Mei , Xiao Xiao‐He
Published: March 2009

Abstract: The protective effects of anthraquinones from Rhubarb, a Chinese herbal medicine, consisting of the root and rhizome ofRheum palmatumL.,R. tanguticum Maxim. Ex Balf., or R. officinale Baill.(family Polygonaceae) were investigated and compared in rats with liver injury induced by α‐naphthylisothiocyanate. α‐Naphthylisothiocyanate was given intragastrically in rats, liver injury with cholestasis developed within 36 hrs, as indicated by characteristic serum levels of glutamate‐pyruvate transaminase, glutamic oxaloacetic transaminase, total bilirubin, direct bilirubin, alkaline phosphatase, γ‐glutamyltransferase and total bile acid. The intragastrical administration of rhein, aloe‐emodin and physione to α‐naphthylisothiocyanate‐treated rats reduced significantly the serum level of both glutamate‐pyruvate transaminase, glutamic oxaloacetic transaminase and the serum total bilirubin, direct bilirubin, alkaline phosphatase, γ‐glutamyltransferase and total bile acid. For all hepatic biochemical markers and cholestasis index, rhein was most efficient. By comparison, the administration of emodin and chrysophanol did not reduce the serum levels of hepatic enzymes glutamate‐pyruvate transaminase and glutamic oxaloacetic transaminase but decreased the levels of serum total bilirubin, direct bilirubin, alkaline phosphatase, γ‐glutamyltransferase, and total bile acid, showing their partial protective effects on cholestatic liver injury. The liver in α‐naphthylisothiocyanate‐treated rats showed cholangiolitic hepatitis characterized by intrahepatic cholestasis, necrosis of hepatocytes and biliary epithelial cells and bile obstruction. The concurrent intragastrical administration of rhein reduced the severity of all morphological alteration, especially the neutrophil infiltration and sinusoid congestion. Rhein, aloe‐emodin, and physione all exhibited protective effects on hepatocytes and cholangiocytes against α‐naphthylisothiocyanate‐induced damage, whereas emodin and chrystophanol provided partial protection.
Molecular evolution of Na+ channels in teleost fishes
Authors: ZAKON Harold H. , JOST Manda C. , ZWICKL Derrick J. , LU Ying , HILLIS David M.
Published: March 2009

Voltage‐dependent sodium channels are critical for electrical excitability. Invertebrates possess a single sodium channel gene; two rounds of genome duplication early in vertebrates increased the number to four. Since the teleost‐tetrapod split, independent gene duplications in each lineage have further increased the number of sodium channel genes to 10 in tetrapods and 8 in teleosts. Here we review how the occurrence of multiple sodium channel paralogs has influenced the evolutionary history of three groups of fishes: pufferfish, gymnotiform and mormyriform electric fish. Pufferfish (tetraodontidae) produce a neurotoxin, tetrodotoxin, that binds to and blocks the pore of sodium channels. Pufferfish evolved resistance to their own toxins by amino acid substitutions in the pore of their sodium channels. These substitutions had to occur in parallel across multiple paralogs for organismal resistance to evolve. Gymnotiform and mormyriform fishes independently evolved electric organs to generate electricity for communication and object localization. Two sodium channel genes are expressed in muscle in most fishes. In both groups of weakly electric fishes, one gene lost its expression in muscle and became compartmentalized in the evolutionary novel electric organ, which is a muscle derivative. This gene then evolved at elevated rates, whereas the gene that is still expressed in muscle does not show elevated rates of evolution. In the electric organ‐expressing gene, amino acid substitutions occur in parts of the channel involved in determining how long the channel will be open or closed. The enhanced rate of sequence evolution of this gene likely underlies the species‐level variations in the electric signal.
Differentially expressed genes identified by cross‐species microarray in the blind cavefish Astyanax
Authors: STRICKLER Allen G. , JEFFERY William R.
Published: March 2009

Changes in gene expression were examined by microarray analysis during development of the eyed surface dwelling (surface fish) and blind cave‐dwelling (cavefish) forms of the teleost Astyanax mexicanus De Filippi, 1853. The cross‐species microarray used surface and cavefish RNA hybridized to a DNA chip prepared from a closely related species, the zebrafish Danio rerio Hamilton, 1822. We identified a total of 67 differentially expressed probe sets at three days post‐fertilization: six upregulated and 61 downregulated in cavefish relative to surface fish. Many of these genes function either in eye development and/or maintenance, or in programmed cell death. The upregulated probe set showing the highest mean fold change was similar to the human ubiquitin specific protease 53 gene. The downregulated probe sets showing some of the highest fold changes corresponded to genes with roles in eye development, including those encoding gamma crystallins, the guanine nucleotide binding proteins Gnat1 and Gant2, a BarH‐like homeodomain transcription factor, and rhodopsin. Downregulation of gamma‐crystallin and rhodopsin was confirmed by in situ hybridization and immunostaining with specific antibodies. Additional downregulated genes encode molecules that inhibit or activate programmed cell death. The results suggest that cross‐species microarray can be used for identifying differentially expressed genes in cavefish, that many of these genes might be involved in eye degeneration via apoptotic processes, and that more genes are downregulated than upregulated in cavefish, consistent with the predominance of morphological losses over gains during regressive evolution.
Doing Culture with Girls Like Me: Why Trying on Gender and Intersectionality Matters
Authors: Williams L. Susan
Published: March 2009

Gendering is not a one‐size‐fits‐all process. Girls try on gender. In particular, girls – conditioned to value connections – search their cultural surroundings for ‘girls like me’ to answer the weighty question, Who am I? However, girls are not simply passive beneficiaries of culture, but actively construct their gendered selves by engaging in or ‘doing’ culture; girls activate certain features salient to their experiences. This paper examines how race, ethnicity, and class arbitrate girls’ gendered identities, emphasizing the concept trying on gender to capture the intersectional and experimental character of these processes. As girls try on gender –a local and culturally specific endeavor – they engage in a fluid, multifaceted, and sometimes tentative gendering process. Cross‐over literature by and for girls lends empirical support to how girls accomplish this multi‐constructed sense of self. The article concludes with implications for studies of girls, including a cautionary note about overemphasis on individualistic agency.
Basic Challenges to Prisoner Reentry
Authors: Anderson‐Facile Doreen
Published: March 2009

Crime, incarceration and prisoner reintegration are pressing issues facing the United States today. The U.S. prison population has increased from 330,000 in 1980 to over 2.2 million prisoners today. As the prison population grows at record rates so, in turn, does the reentry of prisoners into society. Currently, around 700,000 prisoners are released each year from custody and reenter society – nearly 2,000 inmates per day. The transition from prison to the outside world is often difficult for post‐release prisoners, their families, their communities and the larger society. Many formally incarcerated individuals do not have the skills or support to succeed outside prison walls. Unfortunately, when post‐release prisoners are not successfully reintegrated, they are returned to prison and begin the cycle of incarceration.

Practitioners and academics agree that the main components for successful reentry include proper housing, viable employment, and family and community support. However, while there is consensus regarding what post‐release prisoners need for successful reentry there is debate as to which programs and policies work best. This paper examines the basic challenges to reentry and provides a brief summary of the problems with reentry program evaluation.
Knowledge Management Implementation: Modeling the Barriers
Authors: Kant R. , Singh M. D.
Published: March 2009

The purpose of this paper is to present an approach to successful KM implementation by understanding the dynamics among various knowledge management barriers (KMBs) that hinder the implement of KM in organisations. Using interpretive structural modeling (ISM), the research presents a hierarchy-based model and the mutual relationship among the KMBs. The research shows that there is a group of KMBs having high driving power and low dependence which require maximum attention and are of strategic importance. Another group consists of those KMBs which have high dependence and low driving power which necessitate the resultant actions. This categorisation provides a useful tool to top management to differentiate between independent and dependent KMBs and their mutual relationships which would help them to focus on those key KMBs that are most significant for effective KM implementation. Arrangement of KMBs in a hierarchy and the categorisation into driver and dependent categories is an exclusive effort in the area of KM implementation.
Achieving Competitive Advantage through Knowledge Management Initiatives in Small and Medium Software Industry
Authors: Kumarawadu Priyantha
Published: March 2009

Increasing number of small- and medium-scale software companies (SMSCs) has remarkably pressurised them to deliver good quality software products on time at minimum cost. This study attempted to prove that knowledge management initiatives can bestow business opportunities of small- and medium-scale software companies to improve productivity, product quality, flexibility, inter-employee relationships, effective knowledge creation and knowledge utilisation while achieving their cost, quality and time targets. Thus SMSC can gain competitive advantage to sustain their business. We first identified some significant facets which benefit knowledge management initiatives in SMSCs and based on the results of a survey of SMSCs, we proved that knowledge management initiatives have a significant influence on gaining competitive advantage of SMSCs. Therefore, we confirmed that organisation preparedness towards knowledge management initiatives, knowledge management tools and processes, knowledge management education and training and knowledge creation and transformation contribute SMSCs to gain competitive advantage.
Contralateral Acoustic Stimulation Modulates Low-Frequency Biasing of DPOAE: Efferent Influence on Cochlear Amplifier Operating State?
Authors: Abel Cornelius , Wittekindt Anna , Kössl Manfred
Published: March 2009

The mammalian efferent medial olivocochlear system modulates active amplification of low-level sounds in the cochlea. Changes of the cochlear amplifier can be monitored by distortion product otoacoustic emissions (DPOAEs). The quadratic distortion product f2–f1 is known to be sensitive to changes in the operating point of the amplifier transfer function. We investigated the effect of contralateral acoustic stimulation (CAS), known to elicit efferent activity, on DPOAEs in the gerbil. During CAS, a significant increase of the f2–f1 level occurred already at low contralateral noise levels (20 dB SPL), whereas 2f1–f2 was much less affected. The effect strength depended on the CAS level and as shown in experiments with pure tones on the frequency of the contralateral stimulus. In a second approach, we biased the position of the cochlear partition and thus the cochlear amplifier operating point periodically by a ipsilateral low-frequency tone, which resulted in a phase-related amplitude modulation of f2–f1. This modulation pattern was changed considerably during contralateral noise stimulation, in dependence on the noise level. The experimental results were in good agreement with a simple model of distortion product generation and suggest that the olivocochlear efferents might change the operating state of cochlear amplification.
On Motion of Robot End‐Effector Using the Curvature Theory of Timelike Ruled Surfaces with Timelike Rulings
Authors: Ekici Cumali , Ünlütürk Yasin , Dede Mustafa , Ryuh B. S.
Published: March 2009

The trajectory of a robot end‐effector is described by a ruled surface and a spin angle about the ruling of the ruled surface. In this way, the differential properties of motion of the end‐effector are obtained from the well‐known curvature theory of a ruled surface. The curvature theory of a ruled surface generated by a line fixed in the end‐effector referred to as the tool line is used for more accurate motion of a robot end‐effector. In the present paper, we first defined tool trihedron in which tool line is contained for timelike ruled surface with timelike ruling, and transition relations among surface trihedron: tool trihedron, generator trihedron, natural trihedron, and Darboux vectors for each trihedron, were found. Then differential properties of robot end‐effector′s motion were obtained by using the curvature theory of timelike ruled surfaces with timelike ruling.
Bicarbonate Increases Tumor pH and Inhibits Spontaneous Metastases
Authors: Robey Ian F. , Baggett Brenda K. , Kirkpatrick Nathaniel D. , Roe Denise J. , Dosescu Julie , Sloane Bonnie F. , Hashim Arig Ibrahim , Morse David L. , Raghunand Natarajan , Gatenby Robert A. , Gillies Robert J.
Published: March 2009

The external pH of solid tumors is acidic as a consequence of increased metabolism of glucose and poor perfusion. Acid pH has been shown to stimulate tumor cell invasion and metastasis in vitro and in cells before tail vein injection in vivo. The present study investigates whether inhibition of this tumor acidity will reduce the incidence of in vivo metastases. Here, we show that oral NaHCO3 selectively increased the pH of tumors and reduced the formation of spontaneous metastases in mouse models of metastatic breast cancer. This treatment regimen was shown to significantly increase the extracellular pH, but not the intracellular pH, of tumors by 31P magnetic resonance spectroscopy and the export of acid from growing tumors by fluorescence microscopy of tumors grown in window chambers. NaHCO3 therapy also reduced the rate of lymph node involvement, yet did not affect the levels of circulating tumor cells, suggesting that reduced organ metastases were not due to increased intravasation. In contrast, NaHCO3 therapy significantly reduced the formation of hepatic metastases following intrasplenic injection, suggesting that it did inhibit extravasation and colonization. In tail vein injections of alternative cancer models, bicarbonate had mixed results, inhibiting the formation of metastases from PC3M prostate cancer cells, but not those of B16 melanoma. Although the mechanism of this therapy is not known with certainty, low pH was shown to increase the release of active cathepsin B, an important matrix remodeling protease. [Cancer Res 2009;69(6):2260–8]
Epidermal Growth Factor Receptor and PTEN Modulate Tissue Factor Expression in Glioblastoma through JunD/Activator Protein-1 Transcriptional Activity
Authors: Rong Yuan , Belozerov Vladimir E. , Tucker-Burden Carol , Chen Gang , Durden Donald L. , Olson Jeffrey J. , Van Meir Erwin G. , Mackman Nigel , Brat Daniel J.
Published: March 2009

Hypoxia and necrosis are fundamental features of glioblastoma (GBM) and their emergence is critical for the rapid biological progression of this fatal tumor; yet, underlying mechanisms are poorly understood. We have suggested that vaso-occlusion following intravascular thrombosis could initiate or propagate hypoxia and necrosis in GBM. Tissue factor (TF), the main cellular initiator of coagulation, is overexpressed in GBMs and likely favors a thrombotic microenvironment. Epidermal growth factor receptor (EGFR) amplification and PTEN loss are two common genetic alterations seen in GBM but not in lower-grade astrocytomas that could be responsible for TF up-regulation. The most frequent EGFR mutation in GBM involves deletion of exons 2 to 7, resulting in the expression of a constitutively active receptor, EGFRvIII. Here, we show that overexpression of EGFR or EGFRvIII in human glioma cells causes increased basal TF expression and that stimulation of EGFR by its ligand, EGF, leads to a marked dose-dependent up-regulation of TF. In all cases, increased TF expression led to accelerated plasma coagulation in vitro. EGFR-mediated TF expression depended most strongly on activator protein-1 (AP-1) transcriptional activity and was associated with c-Jun NH2-terminal kinase (JNK) and JunD activation. Restoration of PTEN expression in PTEN-deficient GBM cells diminished EGFR-induced TF expression by inhibiting JunD/AP-1 transcriptional activity. PTEN mediated this effect by antagonizing phosphatidylinositol 3-kinase activity, which in turn attenuated both Akt and JNK activities. These mechanisms are likely at work in vivo, as EGFR expression was highly correlated with TF expression in human high-grade astrocytoma specimens. [Cancer Res 2009;69(6):2540–9]
4-Hydroxyestradiol Induces Anchorage-Independent Growth of Human Mammary Epithelial Cells via Activation of IκB Kinase: Potential Role of Reactive Oxygen Species
Authors: Park Sin-Aye , Na Hye-Kyung , Kim Eun-Hee , Cha Young-Nam , Surh Young-Joon
Published: March 2009

Estrogen is converted by cytochrome P450 1B1 to 4-hydroxyestradiol (4-OHE2), a putative carcinogenic metabolite of estrogen. This catechol estrogen metabolite is oxidized further to produce a reactive quinone via semiquinone. Redox cycling between 4-OHE2 and its quinoid generates reactive oxygen species (ROS). ROS not only causes oxidative DNA damage but also promotes neoplastic transformation of initiated cells. In the present study, 4-OHE2 induced anchorage-independent colony formation in human mammary epithelial cells (MCF-10A). MCF-10A cells treated with 4-OHE2 exhibited increased accumulation of intracellular ROS. The antioxidant N-acetyl-l-cysteine inhibited the neoplastic transformation induced by 4-OHE2. ROS overproduced by 4-OHE2 increased the nuclear translocation of nuclear factor-κB (NF-κB) and its DNA binding through induction of IκB kinase α (IKKα) and IKKβ activities. The inhibition of the IKK activities with Bay 11-7082 significantly reduced the anchorage-independent growth induced by 4-OHE2. The 4-OHE2–induced activation of extracellular signal-regulated kinase and Akt resulted in enhanced IKK activities and phosphorylation of IκBα, thereby inducing NF-κB activation and anchorage-independent growth of MCF-10A cells. In conclusion, ROS, concomitantly overproduced during redox cycling of 4-OHE2, activates IKK signaling, which may contribute to neoplastic transformation of MCF-10A cells. [Cancer Res 2009;69(6):2416–24]
MMP13, Birc2 (cIAP1), and Birc3 (cIAP2), Amplified on Chromosome 9, Collaborate with p53 Deficiency in Mouse Osteosarcoma Progression
Authors: Ma Ou , Cai Wei-Wen , Zender Lars , Dayaram Tajhal , Shen Jianhe , Herron Alan J. , Lowe Scott W. , Man Tsz-Kwong , Lau Ching C. , Donehower Lawrence A.
Published: March 2009

Osteosarcoma is the primary malignant cancer of bone and particularly affects adolescents and young adults, causing debilitation and sometimes death. As a model for human osteosarcoma, we have been studying p53+/− mice, which develop osteosarcoma at high frequency. To discover genes that cooperate with p53 deficiency in osteosarcoma formation, we have integrated array comparative genomic hybridization, microarray expression analyses in mouse and human osteosarcomas, and functional assays. In this study, we found seven frequent regions of copy number gain and loss in the mouse p53+/− osteosarcomas but have focused on a recurrent amplification event on mouse chromosome 9A1. This amplicon is syntenic with a similar chromosome 11q22 amplicon identified in several human tumor types. Three genes on this amplicon, the matrix metalloproteinase gene MMP13 and the antiapoptotic genes Birc2 (cIAP1) and Birc3 (cIAP2), show elevated expression in mouse and human osteosarcomas. We developed a functional assay using clonal osteosarcoma cell lines transduced with lentiviral short hairpin RNA vectors to show that down-regulation of MMP13, Birc2, or Birc3 resulted in reduced tumor growth when transplanted into immunodeficient recipient mice. These experiments revealed that high MMP13 expression enhances osteosarcoma cell survival and that Birc2 and Birc3 also enhance cell survival but only in osteosarcoma cells with the chromosome 9A1 amplicon. We conclude that the antiapoptotic genes Birc2 and Birc3 are potential oncogenic drivers in the chromosome 9A1 amplicon. [Cancer Res 2009;69(6):2559–67
Functional Alteration of the Lymphoma Stromal Cell Niche by the Cytokine Context: Role of Indoleamine-2,3 Dioxygenase
Authors: Maby-El Hajjami Hélène , Amé-Thomas Patricia , Pangault Céline , Tribut Olivier , DeVos John , Jean Rachel , Bescher Nadège , Monvoisin Céline , Dulong Joëlle , Lamy Thierry , Fest Thierry , Tarte Karin
Published: March 2009

Human mesenchymal stem cells (MSC) strongly repress activated T-cell proliferation through the production of a complex set of soluble factors, including the tryptophan-catabolizing enzyme indoleamine 2,3-dioxygenase (IDO), which is induced by IFN-γ. Conversely, MSCs support survival of follicular lymphoma (FL) B cells, in particular after exposure to tumor necrosis factor-α (TNF) and lymphotoxin-α1β2 (LT). The role of MSCs on normal and malignant B-cell growth in steady-state and inflammatory conditions remains to be fully explored. We show here that resting MSCs sustain activated normal B-cell proliferation and survival, whereas IFN-γ–conditioned MSCs mediate IDO–dependent B-cell growth arrest and apoptosis. IFN-γ, TNF, and LT are significantly overexpressed by the microenvironment of invaded FL-lymph nodes, but their relative expression patterns are highly heterogeneous between samples. In vitro, IFN-γ abrogates the B-cell supportive phenotype induced by TNF and LT on MSCs. Moreover, IFN-γ overrules the growth promoting effect of MSCs on primary purified FL B cells. Altogether, these results underline the crucial role of the cytokine context in the local crosstalk between malignant cells and their microenvironment and provide new insights into our knowledge of the FL cell niche that emerges as a new promising target for innovative therapeutic strategies. [Cancer Res 2009;69(7):3228–37]
Antitumor Efficacy of the Novel RAF Inhibitor GDC-0879 Is Predicted by BRAFV600E Mutational Status and Sustained Extracellular Signal-Regulated Kinase/Mitogen-Activated Protein Kinase Pathway Suppression
Authors: Hoeflich Klaus P. , Herter Sylvia , Tien Janet , Wong Leo , Berry Leanne , Chan Jocelyn , O'Brien Carol , Modrusan Zora , Seshagiri Somasekar , Lackner Mark , Stern Howard , Choo Edna , Murray Lesley , Friedman Lori S. , Belvin Marcia
Published: March 2009

Oncogenic activation of the BRAF serine/threonine kinase has been associated with initiation and maintenance of melanoma tumors. As such, development of pharmacologic agents to target RAF proteins or their effector kinases is an area of intense investigation. Here we report the biological properties of GDC-0879, a highly selective, potent, and orally bioavailable RAF small-molecule inhibitor. We used extracellular signal-regulated kinase (ERK)-1/2 and mitogen-activated protein kinase/ERK kinase (MEK)-1/2 phosphorylation as biomarkers to explore the relationship between tumor outcome and pharmacodynamic inhibition of the RAF-MEK-ERK pathway. In GDC-0879–treated mice, both cell line– and patient-derived BRAFV600E tumors exhibited stronger and more sustained pharmacodynamic inhibition (>90% for 8 hours) and improved survival compared with mutant KRAS–expressing tumors. Despite the involvement of activated RAF signaling in RAS-induced tumorigenesis, decreased time to progression was observed for some KRAS-mutant tumors following GDC-0879 administration. Moreover, striking differences were noted for RAF and MEK inhibition across a panel of 130 tumor cell lines. Whereas GDC-0879–mediated efficacy was associated strictly with BRAFV600E status, MEK inhibition also attenuated proliferation and tumor growth of cell lines expressing wild-type BRAF (81% KRAS mutant, 38% KRAS wild type). The responsiveness of BRAFV600E melanoma cells to GDC-0879 could be dramatically altered by pharmacologic and genetic modulation of phosphatidylinositol 3-kinase pathway activity. These data suggest that GDC-0879–induced signaling changes are dependent on the point of oncogenic activation within the RAS network. Taken together, these studies increase our understanding of the molecular determinants for antitumor efficacy resulting from RAF pathway inhibition and have implications for therapeutic intervention in the clinic. [Cancer Res 2009;69(7):3042–51]
GD3, an Overexpressed Tumor-Derived Ganglioside, Mediates the Apoptosis of Activated but not Resting T Cells
Authors: Sa Gaurisankar , Das Tanya , Moon Christina , Hilston Cynthia M. , Rayman Patricia A. , Rini Brian I. , Tannenbaum Charles S. , Finke James H.
Published: March 2009

We previously elucidated an important role for gangliosides in renal cell carcinoma–mediated T lymphocyte apoptosis, although the mechanism by which they mediated lymphocyte death remained unclear. Here, we show that when added in purified form, GD3 is internalized by activated T cells, initiating a series of proapoptotic events, including the induction of reactive oxygen species (ROS), an enhancement of p53 and Bax accumulation, an increase in mitochondrial permeability, cytochrome c release, and the activation of caspase-9. GD3-induced apoptosis of activated T cells was dose dependent and inhibitable by pretreating the lymphocytes with N-acetylcysteine, cyclosporin A, or bongkrekic acid, emphasizing the essential role of ROS and mitochondrial permeability to the process. Ganglioside-induced T-cell killing was associated with the caspase-dependent degradation of nuclear factor-κB–inducible, antiapoptotic proteins, including RelA; this suggests that their loss is initiated only after the cascade is activated and that their disappearance amplifies but not triggers GD3 susceptibility. Resting T cells did not internalize appreciable levels of GD3 and did not undergo any of the proapoptotic changes that characterize activated T lymphocytes exposed to the ganglioside. RelA overexpression endows Jurkat cells with resistance to GD3-mediated apoptosis, verifying the role of the intact transcription factor in mediating protection from the ganglioside. [Cancer Res 2009;69(7):3095–104]
Acquisition of Epithelial-Mesenchymal Transition Phenotype of Gemcitabine-Resistant Pancreatic Cancer Cells Is Linked with Activation of the Notch Signaling Pathway
Authors: Wang Zhiwei , Li Yiwei , Kong Dejuan , Banerjee Sanjeev , Ahmad Aamir , Azmi Asfar Sohail , Ali Shadan , Abbruzzese James L. , Gallick Gary E. , Sarkar Fazlul H.
Published: March 2009

Despite rapid advances in many fronts, pancreatic cancer (PC) remains one of the most difficult human malignancies to treat due, in part, to de novo and acquired chemoresistance and radioresistance. Gemcitabine alone or in combination with other conventional therapeutics is the standard of care for the treatment of advanced PC without any significant improvement in the overall survival of patients diagnosed with this deadly disease. Previous studies have shown that PC cells that are gemcitabine-resistant (GR) acquired epithelial-mesenchymal transition (EMT) phenotype, which is reminiscent of “cancer stem-like cells”; however, the molecular mechanism that led to EMT phenotype has not been fully investigated. The present study shows that Notch-2 and its ligand, Jagged-1, are highly up-regulated in GR cells, which is consistent with the role of the Notch signaling pathway in the acquisition of EMT and cancer stem-like cell phenotype. We also found that the down-regulation of Notch signaling was associated with decreased invasive behavior of GR cells. Moreover, down-regulation of Notch signaling by siRNA approach led to partial reversal of the EMT phenotype, resulting in the mesenchymal-epithelial transition, which was associated with decreased expression of vimentin, ZEB1, Slug, Snail, and nuclear factor-κB. These results provide molecular evidence showing that the activation of Notch signaling is mechanistically linked with chemoresistance phenotype (EMT phenotype) of PC cells, suggesting that the inactivation of Notch signaling by novel strategies could be a potential targeted therapeutic approach for overcoming chemoresistance toward the prevention of tumor progression and/or treatment of metastatic PC. [Cancer Res 2009;69(6):2400–7]
GPR109A Is a G-protein–Coupled Receptor for the Bacterial Fermentation Product Butyrate and Functions as a Tumor Suppressor in Colon
Authors: Thangaraju Muthusamy , Cresci Gail A. , Liu Kebin , Ananth Sudha , Gnanaprakasam Jaya P. , Browning Darren D. , Mellinger John D. , Smith Sylvia B. , Digby Gregory J. , Lambert Nevin A. , Prasad Puttur D. , Ganapathy Vadivel
Published: March 2009

Short-chain fatty acids, generated in colon by bacterial fermentation of dietary fiber, protect against colorectal cancer and inflammatory bowel disease. Among these bacterial metabolites, butyrate is biologically most relevant. GPR109A is a G-protein–coupled receptor for nicotinate but recognizes butyrate with low affinity. Millimolar concentrations of butyrate are needed to activate the receptor. Although concentrations of butyrate in colonic lumen are sufficient to activate the receptor maximally, there have been no reports on the expression/function of GPR109A in this tissue. Here we show that GPR109A is expressed in the lumen-facing apical membrane of colonic and intestinal epithelial cells and that the receptor recognizes butyrate as a ligand. The expression of GPR109A is silenced in colon cancer in humans, in a mouse model of intestinal/colon cancer, and in colon cancer cell lines. The tumor-associated silencing of GPR109A involves DNA methylation directly or indirectly. Reexpression of GPR109A in colon cancer cells induces apoptosis, but only in the presence of its ligands butyrate and nicotinate. Butyrate is an inhibitor of histone deacetylases, but apoptosis induced by activation of GPR109A with its ligands in colon cancer cells does not involve inhibition of histone deacetylation. The primary changes in this apoptotic process include down-regulation of Bcl-2, Bcl-xL, and cyclin D1 and up-regulation of death receptor pathway. In addition, GPR109A/butyrate suppresses nuclear factor-κB activation in normal and cancer colon cell lines as well as in normal mouse colon. These studies show that GPR109A mediates the tumor-suppressive effects of the bacterial fermentation product butyrate in colon. [Cancer Res 2009;69(7):2826–32]
Phase I Study of Sequence-Selective Minor Groove DNA Binding Agent SJG-136 in Patients with Advanced Solid Tumors
Authors: Hochhauser Daniel , Meyer Timothy , Spanswick Victoria J. , Wu Jenny , Clingen Peter H. , Loadman Paul , Cobb Margaret , Gumbrell Lindsey , Begent Richard H. , Hartley John A. , Jodrell Duncan
Published: March 2009

Purpose: This phase I dose-escalation study was undertaken to establish the maximum tolerated dose of the sequence-selective minor groove DNA binding agent SJG-136 in patients with advanced solid tumors. The study also investigated antitumor activity and provided pharmacokinetic and pharmacodynamic data.

Experimental Design: Sixteen patients were assigned sequentially to escalating doses of SJG-136 (15-240 μg/m2) given as a 10-minute i.v. infusion every 21 days. The dose was subsequently reduced in incremental steps to 45 μg/m2 due to unexpected toxicity.

Results: The maximum tolerated dose of SJG-136 was 45 μg/m2. The main drug-related adverse event was vascular leak syndrome (VLS) characterized by hypoalbuminemia, pleural effusions, ascites, and peripheral edema. Other unexpected adverse events included elevated liver function tests and fatigue. The VLS and liver toxicity had delayed onset and increased in severity with subsequent cycles. Disease stabilization was achieved for >6 weeks in 10 patients; in 2 patients this was maintained for >12 weeks. There was no evidence of DNA interstrand cross-linking in human blood lymphocytes with the use of the comet assay. Evidence of DNA interaction in lymphocytes and tumor cells was shown through a sensitive γ-H2AX assay. SJG-136 had linear pharmacokinetics across the dose range tested.

Conclusions: SJG-136 was associated with dose-limiting VLS and hepatotoxicity when administered by short injection every 21 days. DNA damage was noted, at all dose levels studied, in circulating lymphocytes. The etiology of the observed toxicities is unclear and is the subject of further preclinical research. Alternative clinical dosing strategies are being evaluated.
Pathologic Correlates of Primary Central Nervous System Lymphoma Defined in an Orthotopic Xenograft Model
Authors: Kadoch Cigall , Dinca Eduard B. , Voicu Ramona , Chen Lingjing , Nguyen Diana , Parikh Seema , Karrim Juliana , Shuman Marc A. , Lowell Clifford A. , Treseler Patrick A. , James C. David , Rubenstein James L.
Published: March 2009

Purpose: The prospect for advances in the treatment of patients with primary central nervous system lymphoma (PCNSL) is likely dependent on the systematic evaluation of its pathobiology. Animal models of PCNSL are needed to facilitate the analysis of its molecular pathogenesis and for the efficient evaluation of novel therapeutics.

Experimental Design: We characterized the molecular pathology of CNS lymphoma tumors generated by the intracerebral implantation of Raji B lymphoma cells in athymic mice. Lymphoma cells were modified for bioluminescence imaging to facilitate monitoring of tumor growth and response to therapy. In parallel, we identified molecular features of lymphoma xenograft histopathology that are evident in human PCNSL specimens.

Results: Intracerebral Raji tumors were determined to faithfully reflect the molecular pathogenesis of PCNSL, including the predominant immunophenotypic state of differentiation of lymphoma cells and their reactive microenvironment. We show the expression of interleukin-4 by Raji and other B lymphoma cell lines in vitro and by Raji tumors in vivo and provide evidence for a role of this cytokine in the M2 polarization of lymphoma macrophages both in the murine model and in diagnostic specimens of human PCNSL.

Conclusion: Intracerebral implantation of Raji cells results in a reproducible and invasive xenograft model, which recapitulates the histopathology and molecular features of PCNSL, and is suitable for preclinical testing of novel agents. We also show for the first time the feasibility and accuracy of tumor bioluminescence in the monitoring of a highly infiltrative brain tumor.
Aberrant Hyperactivation of Akt and Mammalian Target of Rapamycin Complex 1 Signaling in Sporadic Chordomas
Authors: Han Sangyeul , Polizzano Carolyn , Nielsen Gunnlaugur P. , Hornicek Francis J. , Rosenberg Andrew E. , Ramesh Vijaya
Published: March 2009

Purpose: Chordomas are rare, malignant bone neoplasms in which the pathogenic mechanisms remain unknown. Interestingly, tuberous sclerosis complex (TSC) is the only syndrome in which the incidence of chordomas has been described. We previously reported the pathogenic role of the TSC genes in TSC-associated chordomas. In this study, we investigated whether aberrant TSC/mammalian target of rapamycin complex 1 (mTORC1) signaling pathway is associated with sporadic chordomas.

Experimental Design: We assessed the status of mTORC1 signaling in primary tumors/cell lines of sacral chordomas and further examined upstream of mTORC1 signaling, including the PTEN (phosphatase and tensin homologue deleted on chromosome ten) tumor suppressor. We also tested the efficacy of the mTOR inhibitor rapamycin on signaling and growth of chordoma cell lines.

Results: Sporadic sacral chordoma tumors and cell lines examined commonly displayed hyperactivated Akt and mTORC1 signaling. Strikingly, expression of PTEN, a negative regulator of mTORC1 signaling, was not detected or significantly reduced in chordoma-derived cell lines and primary tumors. Furthermore, rapamycin inhibited mTORC1 activation and suppressed proliferation of chordoma-derived cell line.

Conclusions: Our results suggest that loss of PTEN as well as other genetic alterations that result in constitutive activation of Akt/mTORC1 signaling may contribute to the development of sporadic chordomas. More importantly, a combination of Akt and mTORC1 inhibition may provide clinical benefits to chordoma patients.