bluuebunny/crossref_metadata_2025 huggingface dataset:
Utility of circulating IGF-I as a biomarker for assessing body composition changes in men during periods of high physical activity superimposed upon energy and sleep restriction
Authors: Nindl Bradley C. , Alemany Joseph A. , Kellogg Mark D. , Rood Jennifer , Allison Steven A. , Young Andrew J. , Montain Scott J.
Published: April 2007

Insulin-like growth factor (IGF)-I is a biomarker that may have greater utility than other conventional nutritional biomarkers in assessing nutritional, health, and fitness status. We hypothesized that the IGF-I system would directionally track a short-term energy deficit and would be more related to changes in body composition than other nutritional biomarkers. Thirty-five healthy men (24 ± 0.3 yr) underwent 8 days of exercise and energy imbalance. Total and free IGF-I, IGF binding proteins-1, -2, and -3, the acid labile subunit, transferrin, ferritin, retinol binding protein, prealbumin, testosterone, triiodothyronine, thyroxine, and leptin responses were measured. Dual-energy X-ray absorptiometry assessed changes in body mass and composition. Repeated-measures ANOVA, correlation analysis, and receiver operator characteristic curves were used for statistical analyses ( P ≤ 0.05). Body mass (−3.8%), fat-free mass (−2.2%), and fat mass (−12.9%) all decreased. Total and free IGF-I, IGF binding protein-3, and the acid labile subunit and prealbumin, but not transferrin, retinol-binding protein, and ferritin, directionally tracked the energy deficit and losses in body composition. The correlation ( r = 0.43) between changes in free IGF-I and body and fat-free mass was the only significant association observed. Receiver operator characteristic curve analysis revealed that a baseline value < 1.67 for the molar volume ratio of IGF-I to acid labile subunit had an area under the curve of 0.745 and was a significant discriminator for those subjects losing >5% body mass. The IGF-I system is an important adjunct in the overall assessment of adaptation to stress imposed by high levels of physical activity superimposed on energy and sleep restriction and is more closely associated with losses in body mass and fat-free mass than other conventional nutritional biomarkers.
The effects of hypoxia on load compensation during sustained incremental resistive loading in patients with obstructive sleep apnea
Authors: Hlavac Michael C. , Catcheside Peter G. , Adams Amanda , Eckert Danny J. , McEvoy R. Doug
Published: April 2007

Inspiratory load compensation is impaired in patients with obstructive sleep apnea (OSA), a condition characterized by hypoxia during sleep. We sought to compare the effects of sustained hypoxia on ventilation during inspiratory resistive loading in OSA patients and matched controls. Ten OSA patients and 10 controls received 30 min of isocapnic hypoxia (arterial oxygen saturation 80%) and normoxia in random order. Following the gas period, subjects were administered six incremental 2-min inspiratory resistive loads while breathing room air. Ventilation was measured throughout the loading period. In both patients and controls, there was a significant increase in inspiratory time with increasing load ( P = 0.006 and 0.003, respectively), accompanied by a significant fall in peak inspiratory flow ( P = 0.006 and P < 0.001, respectively). The result was a significant fall in minute ventilation in both groups with increasing load ( P = 0.003 and P < 0.001, respectively). There was no difference between the two groups for these parameters. The only difference between the two groups was a transient increase in tidal volume in controls ( P = 0.02) but not in OSA patients ( P = 0.57) during loading. Following hypoxia, there was a significant increase in minute ventilation during loading in both groups ( P < 0.001). These results suggest that ventilation during incremental resistive loading is preserved in OSA patients and that it appears relatively impervious to the effects of hypoxia.
Mathematical Model of Network Dynamics Governing Mouse Sleep–Wake Behavior
Authors: Behn Cecilia G. Diniz , Brown Emery N. , Scammell Thomas E. , Kopell Nancy J.
Published: April 2007

Recent work in experimental neurophysiology has identified distinct neuronal populations in the rodent brain stem and hypothalamus that selectively promote wake and sleep. Mutual inhibition between these cell groups has suggested the conceptual model of a sleep–wake switch that controls transitions between wake and sleep while minimizing time spent in intermediate states. By combining wake- and sleep-active populations with populations governing transitions between different stages of sleep, a “sleep–wake network” of neuronal populations may be defined. To better understand the dynamics inherent in this network, we created a model sleep–wake network composed of coupled relaxation oscillation equations. Mathematical analysis of the deterministic model provides insight into the dynamics underlying state transitions and predicts mechanisms for each transition type. With the addition of noise, the simulated sleep–wake behavior generated by the model reproduces many qualitative and quantitative features of mouse sleep–wake behavior. In particular, the existence of simulated brief awakenings is a unique feature of the model. In addition to capturing the experimentally observed qualitative difference between brief and sustained wake bouts, the model suggests distinct network mechanisms for the two types of wakefulness. Because circadian and other factors alter the fine architecture of sleep–wake behavior, this model provides a novel framework to explore dynamical principles that may underlie normal and pathologic sleep–wake physiology.
Effect of Human Skin-Derived Stem Cells on Vessel Architecture, Tumor Growth, and Tumor Invasion in Brain Tumor Animal Models
Authors: Pisati Federica , Belicchi Marzia , Acerbi Francesco , Marchesi Chiara , Giussani Carlo , Gavina Manuela , Javerzat Sophie , Hagedorn Martin , Carrabba Giorgio , Lucini Valeria , Gaini Sergio Maria , Bresolin Nereo , Bello Lorenzo , Bikfalvi Andreas , Torrente Yvan
Published: April 2007

Glioblastomas represent an important cause of cancer-related mortality with poor survival. Despite many advances, the mean survival time has not significantly improved in the last decades. New experimental approaches have shown tumor regression after the grafting of neural stem cells and human mesenchymal stem cells into experimental intracranial gliomas of adult rodents. However, the cell source seems to be an important limitation for autologous transplantation in glioblastoma. In the present study, we evaluated the tumor targeting and antitumor activity of human skin-derived stem cells (hSDSCs) in human brain tumor models. The hSDSCs exhibit tumor targeting characteristics in vivo when injected into the controlateral hemisphere or into the tail vein of mice. When implanted directly into glioblastomas, hSDSCs distributed themselves extensively throughout the tumor mass, reduced tumor vessel density, and decreased angiogenic sprouts. In addition, transplanted hSDSCs differentiate into pericyte cell and release high amounts of human transforming growth factor-β1 with low expression of vascular endothelial growth factor, which may contribute to the decreased tumor cell invasion and number of tumor vessels. In long-term experiments, the hSDSCs were also able to significantly inhibit tumor growth and to prolong animal survival. Similar behavior was seen when hSDSCs were implanted into two different tumor models, the chicken embryo experimental glioma model and the transgenic Tyrp1-Tag mice. Taken together, these data validate the use of hSDSCs for targeting human brain tumors. They may represent therapeutically effective cells for the treatment of intracranial tumors after autologous transplantation. [Cancer Res 2007;67(7):3054–63]
RaLP, a New Member of the Src Homology and Collagen Family, Regulates Cell Migration and Tumor Growth of Metastatic Melanomas
Authors: Fagiani Ernesta , Giardina Giuseppina , Luzi Lucilla , Cesaroni Matteo , Quarto Micaela , Capra Maria , Germano Giovanni , Bono Maria , Capillo Manuela , Pelicci PierGiuseppe , Lanfrancone Luisa
Published: April 2007

The Src homology and collagen (Src) family of adaptor proteins comprises six Shc-like proteins encoded by three loci in mammals (Shc, Rai, and Sli). Shc-like proteins are tyrosine kinase substrates, which regulate diverse signaling pathways and cellular functions, including Ras and proliferation (p52/p46Shc), phosphatidylinositol 3-kinase and survival (p54Rai), and mitochondrial permeability transition and apoptosis (p66Shc). Here, we report the identification, cloning, and sequence characterization of a new member of the Shc family that we termed RaLP. RaLP encodes a 69-kDa protein characterized by the CH2-PTB-CH1-SH2 modularity, typical of the Shc protein family, and expressed, among adult tissues, only in melanomas. Analysis of RaLP expression during the melanoma progression revealed low expression in normal melanocytes and benign nevi, whereas high levels of RaLP protein were found at the transition from radial growth phase to vertical growth phase and metastatic melanomas, when tumor cells acquire migratory competence and invasive potential. Notably, silencing of RaLP expression in metastatic melanomas by RNA interference reduced tumorigenesis in vivo. Analysis of RaLP in melanoma signal transduction pathways revealed that (a) when ectopically expressed in RaLP-negative melanocytes and nonmetastatic melanoma cells, it functions as a substrate of activated insulin-like growth factor-1 and epidermal growth factor receptors and increases Ras/mitogen-activated protein kinase (MAPK) signaling and cell migration, whereas (b) its silencing in RaLP-positive melanoma cells abrogates cell migration in vitro, without affecting MAPK signaling, suggesting that RaLP activates both Ras-dependent and Ras-independent migratory pathways in melanomas. These findings indicate that RaLP is a specific marker of metastatic melanomas, a critical determinant in the acquisition of the migratory phenotype by melanoma cells, and a potential target for novel anti-melanoma therapeutic strategies. [Cancer Res 2007;67(7):3064–73]
Construction and Validation of Improved Triple Fusion Reporter Gene Vectors for Molecular Imaging of Living Subjects
Authors: Ray Pritha , Tsien Roger , Gambhir Sanjiv Sam
Published: April 2007

Multimodality imaging using several reporter genes and imaging technologies has become an increasingly important tool in determining the location(s), magnitude, and time variation of reporter gene expression in small animals. We have reported construction and validation of several triple fusion genes composed of a bioluminescent, a fluorescent, and a positron emission tomography (PET) reporter gene in cell culture and in living subjects. However, the bioluminescent and fluorescent components of fusion reporter proteins encoded by these vectors possess lesser activities when compared with the bioluminescent and fluorescent components of the nonfusions. In this study, we first created a mutant (mtfl) of a thermostable firefly luciferase (tfl) bearing the peroxisome localization signal to have greater cytoplasmic localization and improved access for its substrate, d-luciferin. Comparison between the three luciferases [mtfl, tfl, and firefly luciferase (fl)] both in cell culture and in living mice revealed that mtfl possessed 6- to 10-fold (in vitro) and 2-fold (in vivo) higher activity than fl. The improved version of the triple fusion vector carrying mtfl as the bioluminescent reporter component showed significantly (P < 0.05) higher bioluminescence than the previous triple fusion vectors. Of the three different red fluorescent reporter genes (jred, hcred, and mrfp1, isolated from jellyfish chromophore, coral Heteractis crispa, and coral Discosoma, respectively) evaluated, mrfp1 was able to preserve highest expression as a component of the triple fusion reporter gene for in vivo fluorescence imaging. A truncated version of wild-type herpes simplex virus 1 (HSV1) thymidine kinase gene (wttk) retained a higher expression level than the truncated mutant HSV1-sr39 TK (ttk) as the third reporter component of this improved triple fusion vector. Multimodality imaging of tumor-bearing mice using bioluminescence and microPET showed higher luciferase activity [(2.7 ± 0.1 versus 1.9 ± 0.1) × (106 p/s/cm2/sr)] but similar level of fluorine-18–labeled 2′-fluoro-2′-deoxyarabinofuranosyl-5-ethyluracil (18F-FEAU) uptake (1.37 ± 0.15 versus 1.37 ± 0.2) percentage injected dose per gram] by mtfl-mrfp1-wttk–expressing tumors compared with the fl-mrfp1-wttk–expressing tumors. Both tumors showed 4- to 5-fold higher accumulation (P < 0.05) of 18F-FEAU than fluorine-18–labeled 9-(4-fluoro-3-hydroxymethylbutyl)guanine. This improved triple fusion reporter vector will enable high sensitivity detection of lower numbers of cells from living animals using the combined bioluminescence, fluorescence, and microPET imaging techniques. [Cancer Res 2007;67(7):3085–93]
Androgen Deprivation Increases p300 Expression in Prostate Cancer Cells
Authors: Heemers Hannelore V. , Sebo Thomas J. , Debes Jose D. , Regan Kevin M. , Raclaw Kristin A. , Murphy Linda M. , Hobisch Alfred , Culig Zoran , Tindall Donald J.
Published: April 2007

Standard therapy for nonorgan confined prostate cancer aims to block the production or action of androgens. Although initially successful, antiandrogen therapy eventually fails and androgen depletion independent (ADI) disease emerges. Remarkably, ADI prostate cancers still rely on a functional androgen receptor (AR). Aberrant expression of coregulatory proteins required for the formation of productive AR transcriptional complexes is critical for ADI AR activation. Previously, we have shown that the transcriptional coactivator p300 is required for ADI activation of the AR and is up-regulated in prostate cancer, in which its expression is associated with cell proliferation and predicts aggressive tumor features. The mechanism responsible for the deregulated expression of p300, however, remains elusive. Here, we show that p300 expression in prostate cancer cells is subject to androgen regulation. In several prostate cancer model systems, addition of synthetic and natural androgens led to decreased expression of p300 in a time-dependent and dose-dependent manner. Experiments using AR antagonists or small interfering RNA targeting the AR revealed that down-regulation of p300 depends entirely on the presence of a functional AR. It is noteworthy that androgens down-regulated p300 protein expression while leaving messenger levels unaltered. Conversely, both short-term and long-term androgen deprivation resulted in marked up-regulation of p300 expression. The androgen deprivation–induced increase in p300 expression was not affected by the addition of cytokines or growth factors or by cotreatment with antiandrogens. Moreover, increased p300 expression upon androgen starvation is crucial for prostate cancer cell proliferation, as loss of p300 expression severely reduces expression of cyclins governing G1-S and G2-M cell cycle transition and decreases 5-bromo-2′-deoxyuridine incorporation. [Cancer Res 2007;67(7):3422–30]
Two Common Chromosome 8q24 Variants Are Associated with Increased Risk for Prostate Cancer
Authors: Wang Liang , McDonnell Shannon K. , Slusser Joshua P. , Hebbring Scott J. , Cunningham Julie M. , Jacobsen Steven J. , Cerhan James R. , Blute Michael L. , Schaid Daniel J. , Thibodeau Stephen N.
Published: April 2007

Two variants (rs1447295/DG8S737) of chromosome 8q24 were recently reported to be associated with increased risk of prostate cancer (PC). To confirm this finding, we genotyped and compared the frequencies of these polymorphisms among 1,121 Caucasian men with PC (435 men with familial PC, 491 men with sporadic PC, and 195 men with aggressive PC) to 545 population-based controls. For the single nucleotide polymorphism marker rs1447295, frequencies of the minor allele (A) were 10.3% in controls, 11.9% in sporadic cases, 16.7% in familial cases, and 17.2% in aggressive cases. Compared with controls, the A allele was significantly more common in both familial PC [odds ratios (OR), 1.93; 95% confidence intervals (95% CI), 1.37–2.72; P = 0.0004] and aggressive PC (OR, 1.87; 95% CI, 1.28–2.74; P = 0.0005) but not for sporadic PC (OR, 1.16; 95% CI, 0.85–1.58; P = 0.25). Although the A allele was more frequent in aggressive PC cases when compared with controls, the allele frequencies were similar among cases with high- and low-grade PC (Gleason grades <7 and ≥7, respectively). For the microsatellite marker DG8S737, the −8 allele was significantly more frequent in familial PC (OR, 1.68; 95% CI, 1.09–2.60; P = 0.031), whereas the −10 allele was more frequent in aggressive PC (OR, 2.85; 95% CI, 1.52–5.36; P = 0.0004). Haplotype analysis showed significant differences in haplotype frequencies between the familial PC (P = 0.006) and aggressive PC (P = 0.005) cases versus controls. The −8/A haplotype showed the strongest association with familial PC (P = 0.008), whereas the −10/A haplotype was most strongly associated with aggressive PC (P = 0.00005). These results further confirm the importance of these two polymorphic variants (rs1447295 and DG8S737) as risk factors for PC. However, the mechanism explaining this increased risk has not yet been established. [Cancer Res 2007;67(7):2944–50]
Mutant V600E BRAF Increases Hypoxia Inducible Factor-1α Expression in Melanoma
Authors: Kumar Suresh M. , Yu Hong , Edwards Robin , Chen Lianjun , Kazianis Steven , Brafford Patricia , Acs Geza , Herlyn Meenhard , Xu Xiaowei
Published: April 2007

Mutations in the BRAF serine/threonine kinase gene are frequently found in cutaneous melanomas. Activation of hypoxia inducible factor-1α (HIF-1α) in response to both hypoxic stress and oncogenic signals has important implications in cancer development and progression. Here, we report that mutant BRAFV600E increases HIF-1α expression in melanoma cells. Our microarray profiling data in 35 melanoma and melanocyte cell lines showed that HIF-1α gene expression was significantly increased in melanomas harboring BRAFV600E mutation. Stable suppression of mutant BRAFV600E or both wild-type and mutant BRAFV600E by RNA interference in melanoma cells resulted in significantly decreased HIF-1α expression. Knockdown of mutant BRAFV600E induced significant reduction of cell survival and proliferation under hypoxic conditions, whereas knockdown of both wild-type and mutant BRAFV600E resulted in further reduction. The effects of BRAF knockdown can be rescued by reintroducing BRAFV600E into tumor cells. Transfection of BRAFV600E into melanoma cells with wild-type BRAF induced significantly more hypoxic tolerance. Knockdown of HIF-1α in melanoma cells resulted in decreased cell survival under hypoxic conditions. Pharmacologic inhibition of BRAF by BAY 43-9006 also resulted in decreased HIF-1α expression. Although HIF-1α translational rate was not changed, the protein was less stable in BRAF knockdown cells. In additional, von Hippel-Lindau protein expression was significantly increased in BRAF knockdown cells. Our data show for the first time that BRAFV600E mutation increases HIF-1α expression and melanoma cell survival under hypoxic conditions and suggest that effects of the oncogenic V600E BRAF mutation may be partially mediated through the HIF-1α pathway. [Cancer Res 2007;67(7):3177–84]
Relation of a Hypoxia Metagene Derived from Head and Neck Cancer to Prognosis of Multiple Cancers
Authors: Winter Stuart C. , Buffa Francesca M. , Silva Priyamal , Miller Crispin , Valentine Helen R. , Turley Helen , Shah Ketan A. , Cox Graham J. , Corbridge Rogan J. , Homer Jarrod J. , Musgrove Brian , Slevin Nick , Sloan Philip , Price Pat , West Catharine M.L. , Harris Adrian L.
Published: April 2007

Affymetrix U133plus2 GeneChips were used to profile 59 head and neck squamous cell cancers. A hypoxia metagene was obtained by analysis of genes whose in vivo expression clustered with the expression of 10 well-known hypoxia-regulated genes (e.g., CA9, GLUT1, and VEGF). To minimize random aggregation, strongly correlated up-regulated genes appearing in >50% of clusters defined a signature comprising 99 genes, of which 27% were previously known to be hypoxia associated. The median RNA expression of the 99 genes in the signature was an independent prognostic factor for recurrence-free survival in a publicly available head and neck cancer data set, outdoing the original intrinsic classifier. In a published breast cancer series, the hypoxia signature was a significant prognostic factor for overall survival independent of clinicopathologic risk factors and a trained profile. The work highlights the validity and potential of using data from analysis of in vitro stress pathways for deriving a biological metagene/gene signature in vivo. [Cancer Res 2007;67(7):3441–9]
N-Cadherin Signaling Potentiates Mammary Tumor Metastasis via Enhanced Extracellular Signal-Regulated Kinase Activation
Authors: Hulit James , Suyama Kimita , Chung Su , Keren Rinat , Agiostratidou Georgia , Shan Weisong , Dong Xinyuan , Williams Terence M. , Lisanti Michael P. , Knudsen Karen , Hazan Rachel B.
Published: April 2007

N-cadherin is up-regulated in aggressive breast carcinomas, but its mechanism of action in vivo remains unknown. Transgenic mice coexpressing N-cadherin and polyomavirus middle T antigen (PyVmT) in the mammary epithelium displayed increased pulmonary metastasis, with no differences in tumor onset or growth relative to control PyVmT mice. PyVmT-N-cadherin tumors contained higher levels of phosphorylated extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK) than PyVmT controls, and phosphorylated ERK staining was further increased in pulmonary metastases. Tumor cell isolates from PyVmT-N-cadherin mice exhibited enhanced ERK activation, motility, invasion, and matrix metalloproteinase-9 (MMP-9) expression relative to PyVmT controls. MAPK/ERK kinase 1 inhibition in PyVmT-N-cadherin cells reduced MMP-9 production and invasion but not motility. Furthermore, inactivation of fibroblast growth factor receptor in PyVmT-N-cadherin cells reduced motility, invasion, and ERK activation but had no effect on PyVmT cells. Thus, de novo expression of N-cadherin in mammary ducts enhances metastasis of breast tumors via enhanced ERK signaling. [Cancer Res 2007;67(7):3106–16]
Senescent Human Fibroblasts Increase the Early Growth of Xenograft Tumors via Matrix Metalloproteinase Secretion
Authors: Liu Dan , Hornsby Peter J.
Published: April 2007

Although cellular senescence is believed to have a tumor suppressor function, senescent cells have been shown to increase the potential for growth of adjacent cancer cells in animal models. Replicatively senescent human fibroblasts increase the growth of cotransplanted cancer cells in vivo, but the role of cells that have undergone damage-mediated stress-induced premature senescence (SIPS) has not been studied in mouse transplant models. Here, we show that human fibroblasts that have undergone SIPS by exposure to the DNA-damaging agent bleomycin increase the growth of cotransplanted cancer cells (MDA-MB-231) in immunodeficient mice. Xenografts containing SIPS fibroblasts (SIPSF) exhibited early tissue damage as evidenced by fluid accumulation (edema). Cancer cells adjacent to the fluid showed increased DNA synthesis. Fluid accumulation, increased xenograft size, and increased cell proliferation were all reduced by the matrix metalloproteinase (MMP) inhibitor GM6001. MMPs and other genes characteristic of inflammation/tissue injury were overexpressed in SIPSF. Inhibition of MMP activity did not affect SIPSF stimulation of cancer cell proliferation in culture. However, another overexpressed product (hepatocyte growth factor) did have a direct mitogenic action on cancer cells. Based on the present results, we propose that senescent cells may promote cancer growth both by a direct mitogenic effect and by an indirect effect via tissue damage. Senescent stromal cells may cause an MMP-mediated increase in permeability of adjacent capillaries, thereby exposing incipient cancer cells to increased levels of mitogens, cytokines, and other plasma products. This exposure may increase cancer cell proliferation and result in promotion of preneoplastic cells. [Cancer Res 2007;67(7):3117–26]
Cellular Transformation and Activation of the Phosphoinositide-3-Kinase–Akt Cascade by the ETV6-NTRK3 Chimeric Tyrosine Kinase Requires c-Src
Authors: Jin Wook , Yun Chohee , Hobbie Amy , Martin Matthew J. , Sorensen Poul H.B. , Kim Seong-Jin
Published: April 2007

The ETV6-NTRK3 (EN) chimeric tyrosine kinase, a potent oncoprotein expressed in tumors derived from multiple cell lineages, functions as a constitutively active protein-tyrosine kinase. ETV6-NTRK expression leads to the constitutive activation of two major effector pathways of wild-type NTRK3, namely, the Ras–mitogen-activated protein kinase (MAPK) mitogenic pathway and the phosphoinositide-3-kinase (PI3K)-Akt pathway mediating cell survival, and both are required for EN transformation. However, it remains unclear how ETV6-NTRK3 activates Ras-Erk1/2 and/or PI3K-Akt cascades. Here, we define some aspects of the molecular mechanisms regulating ETV6-NTRK–dependent Ras-Erk1/2 and PI3K-Akt activation. We show that ETV6-NTRK3 associates with c-Src, and that treatment with SU6656, a c-Src inhibitor, completely blocks ETV6-NTRK-transforming activity. Treatment of NIH3T3 cells expressing ETV6-NTRK3 with SU6656 attenuated the activation of Ras-Erk1/2 and PI3K-Akt. Suppression of c-Src by RNA interference in NIH3T3-ETV6-NTRK3 cells resulted in markedly decreased expression of cyclin D1 and suppression of activation of Ras-Erk1/2 and PI3K-Akt. However, in Src-deficient cells, the ETV6-NTRK3 failed to activate the PI3K-Atk pathway, but not the Ras-Erk1/2 pathway. Therefore, these data indicate that ETV6-NTRK3 induces the PI3K-Akt cascade through the activation of c-Src. [Cancer Res 2007;67(7):3192–200]
Induction of Cdc25B Regulates Cell Cycle Resumption after Genotoxic Stress
Authors: Bansal Pallavi , Lazo John S.
Published: April 2007

Cdc25 phosphatases propel cell cycle progression by activating cyclin-dependent kinases (Cdk). DNA damage is generally thought to inhibit Cdc25 functionality by inducing proteasomal degradation of Cdc25A and phosphorylation-mediated sequestration of Cdc25B and Cdc25C to the cytoplasm. More recently, a critical role for Cdc25B in the resumption of cell cycle progression through mitosis after DNA damage has been identified. In this study, the fate of Cdc25B after mechanistically distinct DNA-damaging agents (etoposide, cisplatin, bleomycin, ionizing irradiation, or UV irradiation) was examined, and surprisingly a rapid increase in cellular Cdc25B levels was observed after DNA damage. Using UV irradiation as the prototypic damaging agent, we found that the increase in Cdc25B levels was checkpoint dependent and was controlled by a p53-independent mechanism. Cdc25B levels controlled the number of cells progressing into mitosis after UV, but they did not affect G2-M checkpoint engagement immediately after DNA damage. Increased Cdc25B reduced the time required for cell cycle resumption. These data support a model in which Cdc25B accumulation is an important anticipatory event for cell cycle resumption after DNA damage. [Cancer Res 2007;67(7):3356–63]
2-Deoxy-d-Glucose Combined with Cisplatin Enhances Cytotoxicity via Metabolic Oxidative Stress in Human Head and Neck Cancer Cells
Authors: Simons Andrean L. , Ahmad Iman M. , Mattson David M. , Dornfeld Kenneth J. , Spitz Douglas R.
Published: April 2007

Glucose deprivation has been hypothesized to cause cytotoxicity by inducing metabolic oxidative stress in human cancer cells. The current work tests the hypothesis that 2-deoxy-d-glucose (2DG) combined with cisplatin [cis-diamminedichloroplatinum(II)] can enhance cytotoxicity in human head and neck cancer cells (FaDu) by mechanisms involving oxidative stress. Exposure of FaDu cells to the combination of 2DG and cisplatin resulted in a significant decrease in cell survival when compared with 2DG or cisplatin alone. Treatment with 2DG and cisplatin also caused perturbations in parameters indicative of oxidative stress, including decreased intracellular total glutathione and increased percentage of glutathione disulfide. Simultaneous treatment with the thiol antioxidant N-acetylcysteine (NAC) inhibited parameters indicative of oxidative stress, as well as protected FaDu cells from the cytotoxic effects of cisplatin alone and the combination of 2DG and cisplatin. In addition, polyethylene glycol–conjugated antioxidant enzymes (PEG-superoxide dismutase and PEG-catalase) also protected FaDu cells from 2DG toxicity. An inhibitor of glutathione synthesis, l-buthionine-[S,R]-sulfoximine (BSO), sensitized FaDu cells to the cytotoxic effects of 2DG and cisplatin, and these effects were inhibited by NAC. Furthermore, the combination of 2DG, cisplatin, and BSO significantly increased the percentage of glutathione disulfide, which was also inhibited by NAC. These results support the hypothesis that exposure of human head and neck cancer cells to 2DG combined with cisplatin enhances cytotoxicity via metabolic oxidative stress. These findings provide a strong biochemical rationale for evaluating inhibitors of glucose and hydroperoxide metabolism in combination with cisplatin for the treatment of head and neck cancer. [Cancer Res 2007;67(7):3364–70]
Parthenolide Inhibits Tubulin Carboxypeptidase Activity
Authors: Fonrose Xavier , Ausseil Frédéric , Soleilhac Emmanuelle , Masson Véronique , David Bruno , Pouny Isabelle , Cintrat Jean-Christophe , Rousseau Bernard , Barette Caroline , Massiot Georges , Lafanechère Laurence
Published: April 2007

Microtubules are centrally involved in cell division, being the principal components of mitotic spindle. Tubulin, the constituent of microtubules, can be cyclically modified on its α-subunit by enzymatic removal of the COOH-terminal tyrosine residue by an ill-defined tubulin carboxypeptidase (TCP) and its readdition by tubulin tyrosine ligase (TTL). We and others have previously shown that suppression of TTL and resulting accumulation of detyrosinated tubulin are frequent in human cancers of poor prognosis. Explanations for the involvement of TTL and detyrosinated tubulin in tumor progression arise from the recent discovery that tubulin detyrosination leads to CAP-Gly protein mislocalization, which correlates with defects in spindle positioning during mitosis. Impaired control of spindle positioning is one factor favoring tumor invasiveness. Thus, TCP could be a target for developing novel therapeutic strategies against advanced stages of cancers. Inhibitors of TCP, by reversing abnormal detyrosinated tubulin accumulation in tumor cells, could impair tumor progression. TCP has never been isolated and this has hampered search of specific inhibitors. In this article, we describe a cell-based assay of TCP activity and its use to screen a library of natural extracts for their inhibitory potency. This led to the isolation of two sesquiterpene lactones. We subsequently found that parthenolide, a structurally related compound, can efficiently inhibit TCP. This inhibitory activity is a new specific property of parthenolide independent of its action on the nuclear factor-κB pathway. Parthenolide is also known for its anticancer properties. Thus, TCP inhibition could be one of the underlying mechanisms of these anticancer properties. [Cancer Res 2007;67(7):3371–8]
Six1 Overexpression in Ovarian Carcinoma Causes Resistance to TRAIL-Mediated Apoptosis and Is Associated with Poor Survival
Authors: Behbakht Kian , Qamar Lubna , Aldridge Carrie S. , Coletta Ricardo D. , Davidson Susan A. , Thorburn Andrew , Ford Heide L.
Published: April 2007

Tumorigenesis can arise from inappropriate activation of developmental genes in mature tissues. Here, we show that the developmental regulator Six1 is overexpressed in ovarian carcinoma cell lines (OCC) compared with normal ovarian surface epithelium. As observed in other cancers, Six1 overexpression in OCC leads to increased A-type cyclin expression and increased proliferation. In addition, Six1 overexpression renders OCC resistant to tumor necrosis factor–related apoptosis inducing ligand (TRAIL)–mediated apoptosis, and Six1 knockdown in the TRAIL-resistant SKOV3 ovarian carcinoma line dramatically sensitizes the cells to TRAIL. Because inactivation of the TRAIL response has been linked to metastasis, and because antibodies and recombinant ligand that activate the TRAIL pathway are currently in clinical trials against ovarian carcinoma, we screened normal ovarian and carcinoma specimens for Six1 mRNA. Six1 was overexpressed in 50% of the early-stage (stage I) and 63% of the late-stage (stages II, III, and IV) ovarian carcinomas examined, with late-stage carcinomas expressing ∼3-fold higher Six1 mRNA levels on average compared with early-stage tumors. Importantly, in patients with late-stage disease, high Six1 expression was associated with significantly shortened survival (P = 0.0015). These data suggest that Six1 may contribute to ovarian epithelial carcinogenesis by simultaneously increasing proliferation and decreasing TRAIL-mediated apoptosis and imply that Six1 may be an important determinant of TRAIL therapy response that should be considered in patient selection for TRAIL-related clinical trials. [Cancer Res 2007;67(7):3036–42]
Silibinin Inhibits Inflammatory and Angiogenic Attributes in Photocarcinogenesis in SKH-1 Hairless Mice
Authors: Gu Mallikarjuna , Singh Rana P. , Dhanalakshmi Sivanandhan , Agarwal Chapla , Agarwal Rajesh
Published: April 2007

Sunscreens partially filter UVB and, therefore, could partially prevent skin cancer; however, efficient approaches are desired to effectively prevent photocarcinogenesis. It is hypothesized that nontoxic pharmacologically active natural compounds can increase photoprotective effects. Our completed studies suggest that silibinin, a bioactive phytochemical, strongly prevents photocarcinogenesis; however, its mechanism is not fully understood. Herein, for the first time, we used a clinically relevant UVB dose (30 mJ/cm2/day) to examine the photoprotective effect and associated mechanisms of silibinin in SKH1 hairless mice. Topical or dietary silibinin treatment caused a strong protection against photocarcinogenesis in terms of delay in tumor appearance, multiplicity, and volume. Analyses of normal skin, uninvolved skin from tumor-bearing mice, and skin tumors showed a statistically significant decrease (P < 0.05–0.001) in inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) levels by silibinin. Concomitantly, phospho–signal transducers and activators of transcription 3 (Tyr705) and phospho-p65(Ser536) were also decreased by silibinin, which are potential up-stream regulators of iNOS and COX-2. Simultaneously, silibinin also decreased UVB-caused increase in cell proliferation and microvessel density. In tumors, hypoxia-inducible factor 1α (HIF-1α) and vascular endothelial growth factor protein levels were decreased by silibinin. Further analysis showed that silibinin inhibited UVB-caused phosphorylation and nuclear translocation of STAT3 and p65, as well as nuclear factor κB (NF-κB) DNA binding activity. Together, these results suggest that silibinin causes a strong protective effect against photocarcinogenesis via down-regulation of inflammatory and angiogenic responses, involving HIF-1α, STAT3, and NF-κB transcription factors, as well as COX2 and iNOS. [Cancer Res 2007;67(7):3483–91]
Cholesterol Starvation Induces Differentiation of Human Leukemia HL-60 Cells
Authors: Sánchez-Martín Carolina C. , Dávalos Alberto , Martín-Sánchez Covadonga , de la Peña Gema , Fernández-Hernando Carlos , Lasunción Miguel A.
Published: April 2007

Cholesterol metabolism is particularly active in malignant, proliferative cells, whereas cholesterol starvation has been shown to inhibit cell proliferation. Inhibition of enzymes involved in cholesterol biosynthesis at steps before the formation of 7-dehydrocholesterol has been shown to selectively affect cell cycle progression from G2 phase in human promyelocytic HL-60 cells. In the present work, we explored whether cholesterol starvation by culture in cholesterol-free medium and treatment with different distal cholesterol biosynthesis inhibitors induces differentiation of HL-60 cells. Treatment with SKF 104976, an inhibitor of lanosterol 14-α demethylase, or with zaragozic acid, which inhibits squalene synthase, caused morphologic changes alongside respiratory burst activity and expression of cluster of differentiation antigen 11c (CD11c) but not cluster of differentiation antigen 14. These effects were comparable to those produced by all-trans retinoic acid, which induces HL-60 cells to differentiate following a granulocyte lineage. In contrast, they differed from those produced by vitamin D3, which promotes monocyte differentiation. The specificity of the response was confirmed by addition of cholesterol to the culture medium. Treatment with PD 98059, an inhibitor of extracellular signal–regulated kinase, abolished both the activation of NADPH oxidase and the expression of the CD11c marker. In sharp contrast, BM 15766, which inhibits sterol Δ7-reductase, failed to induce differentiation or arrest cell proliferation. These results show that changes in the sterol composition may trigger a differentiation response and highlight the potential of cholesterol pathway inhibition as a possible tool for use in cancer therapy. [Cancer Res 2007;67(7):3379–86]
Mammalian Tumor Xenografts Induce Neovascularization in Zebrafish Embryos
Authors: Nicoli Stefania , Ribatti Domenico , Cotelli Franco , Presta Marco
Published: April 2007

The zebrafish (Danio rerio)/tumor xenograft model represents a powerful new model system in cancer. Here, we describe a novel exploitation of the zebrafish model to investigate tumor angiogenesis, a pivotal step in cancer progression and target for antitumor therapies. Human and murine tumor cell lines that express the angiogenic fibroblast growth factor (FGF) 2 and/or vascular endothelial growth factor (VEGF) induce the rapid formation of a new microvasculature when grafted close to the developing subintestinal vessels of zebrafish embryos at 48 h postfertilization. Instead, no angiogenic response was exerted by related cell clones defective in the production of these angiogenic growth factors. The newly formed blood vessels sprout from the subintestinal plexus of the zebrafish embryo, penetrate the tumor graft, and express the transcripts for the zebrafish orthologues of the early endothelial markers Fli-1, VEGF receptor-2 (VEGFR2/KDR), and VE-cadherin. Accordingly, green fluorescent protein–positive neovessels infiltrate the graft when tumor cells are injected in transgenic VEGFR2:G-RCFP zebrafish embryos that express green fluorescent protein under the control of the VEGFR2/KDR promoter. Systemic exposure of zebrafish embryos immediately after tumor cell injection to prototypic antiangiogenic inhibitors, including the FGF receptor tyrosine kinase inhibitor SU5402 and the VEGFR2/KDR tyrosine kinase inhibitor SU5416, suppresses tumor-induced angiogenesis without affecting normal blood vessel development. Accordingly, VE-cadherin gene inactivation by antisense morpholino oligonucleotide injection inhibits tumor neovascularization without affecting the development of intersegmental and subintestinal vessels. These data show that the zebrafish/tumor xenograft model represents a novel tool for investigating the neovascularization process exploitable for drug discovery and gene targeting in tumor angiogenesis. [Cancer Res 2007;67(7):2927–31]
Gene Expression Signature of Human Cancer Cell Lines Treated with the Ras Inhibitor Salirasib (S-Farnesylthiosalicylic Acid)
Authors: Blum Roy , Elkon Ran , Yaari Shira , Zundelevich Adi , Jacob-Hirsch Jasmine , Rechavi Gideon , Shamir Ron , Kloog Yoel
Published: April 2007

Deregulation of Ras pathways results in complex abnormalities of multiple signaling cascades that contribute to human malignancies. Ras is therefore considered an appropriate target for cancer therapy. In light of the complexity of the deregulated Ras pathway, it is important to decipher at the molecular level the response of cancer cells to Ras inhibitors that would reregulate it. In the present study, we used gene expression profiling as a robust method for the global dissection of gene expression alterations that resulted from treatment with the Ras inhibitor S-farnesylthiosalicylic acid (FTS; salirasib). Use of a ranking-based procedure, combined with functional analysis and promoter sequence analysis, enabled us to decipher the common and most prominent patterns of the transcriptional response of five different human cancer cell lines to FTS. Remarkably, the analysis identified a distinctive core transcriptional response to FTS that was common to all cancer cell lines tested. This signature fits well to a recently described deregulated Ras pathway signature that predicted sensitivity to FTS. Taken together, these studies provide strong support for the conclusion that FTS specifically reregulates defective Ras pathways in human tumor cells. Ras pathway reregulation by FTS was manifested by repression of E2F-regulated and NF-Y–regulated genes and of the transcription factor FOS (all of which control cell proliferation), repression of survivin expression (which blocks apoptosis), and induction of activating transcription factor–regulated and Bach2-regulated genes (which participate in translation and stress responses). Our results suggest that cancer patients with deregulated Ras pathway tumors might benefit from FTS treatment. [Cancer Res 2007;67(7):3320–8]
Hyperthermia Activates a Subset of Ataxia-Telangiectasia Mutated Effectors Independent of DNA Strand Breaks and Heat Shock Protein 70 Status
Authors: Hunt Clayton R. , Pandita Raj K. , Laszlo Andrei , Higashikubo Ryuji , Agarwal Manjula , Kitamura Tetsuya , Gupta Arun , Rief Nicole , Horikoshi Nobuo , Baskaran Rajeskaran , Lee Ji-Hoon , Löbrich Markus , Paull Tanya T. , Roti Roti Joseph L. , Pandita Tej K.
Published: April 2007

All cells have intricately coupled sensing and signaling mechanisms that regulate the cellular outcome following exposure to genotoxic agents such as ionizing radiation (IR). In the IR-induced signaling pathway, specific protein events, such as ataxia-telangiectasia mutated protein (ATM) activation and histone H2AX phosphorylation (γ-H2AX), are mechanistically well characterized. How these mechanisms can be altered, especially by clinically relevant agents, is not clear. Here we show that hyperthermia, an effective radiosensitizer, can induce several steps associated with IR signaling in cells. Hyperthermia induces γ-H2AX foci formation similar to foci formed in response to IR exposure, and heat-induced γ-H2AX foci formation is dependent on ATM but independent of heat shock protein 70 expression. Hyperthermia also enhanced ATM kinase activity and increased cellular ATM autophosphorylation. The hyperthermia-induced increase in ATM phosphorylation was independent of Mre11 function. Similar to IR, hyperthermia also induced MDC1 foci formation; however, it did not induce all of the characteristic signals associated with irradiation because formation of 53BP1 and SMC1 foci was not observed in heated cells but occurred in irradiated cells. Additionally, induction of chromosomal DNA strand breaks was observed in IR-exposed but not in heated cells. These results indicate that hyperthermia activates signaling pathways that overlap with those activated by IR-induced DNA damage. Moreover, prior activation of ATM or other components of the IR-induced signaling pathway by heat may interfere with the normal IR-induced signaling required for chromosomal DNA double-strand break repair, thus resulting in increased cellular radiosensitivity. [Cancer Res 2007;67(7):3010–7]
Detection of DNA Copy Number Changes and Oncogenic Signaling Abnormalities from Gene Expression Data RevealsMYCActivation in High-Grade Papillary Renal Cell Carcinoma
Authors: Furge Kyle A. , Chen Jindong , Koeman Julie , Swiatek Pamela , Dykema Karl , Lucin Kseniji , Kahnoski Richard , Yang Ximing J. , Teh Bin Tean
Published: April 2007

Papillary renal cell carcinoma (RCC) represents 10% to 15% of adult renal neoplasms; however, the molecular genetic events that are associated with the development and progression of sporadic papillary RCC remain largely unclear. Papillary RCCs can be divided into two subtypes based on histologic, cytogenetic, and gene expression differences. Type 1 tumors (∼60–70%) are generally low grade with favorable outcome, whereas type 2 tumors (∼30–40%) are associated with increased cytogenetic complexity, high tumor grade, and poor prognosis. In this study, computational analysis of gene expression data derived from papillary RCC revealed that a transcriptional signature indicative of MYC pathway activation is present in high-grade type 2 papillary RCC. The MYC signature is associated with amplification of chromosome 8q and overexpression of MYC that maps to chromosome 8q24. The importance of MYC activation was confirmed by both pharmacologic and short interfering RNA–mediated inhibition of active Myc signaling in a cell line model of type 2 papillary RCC. These results provide both computational and genetic evidence that activation of Myc is associated with the aggressiveness of papillary type 2 RCC. Therefore, it will be useful to consider inhibition of components of the MYC signaling pathway as avenues for therapeutic intervention in high-grade papillary RCC. [Cancer Res 2007;67(7):3171–6]
Targeting Multiple Arms of the Apoptotic Regulatory Machinery
Authors: Dai Yun , Grant Steven
Published: April 2007

ABT-737 targets Bcl-2/Bcl-xL but not Mcl-1, which confers resistance to this novel agent. Here, we summarize recent findings indicating that Mcl-1 represents a critical determinant of ABT-737 sensitivity and resistance, and that Mcl-1 down-regulation by various pharmacologic agents or genetic approaches dramatically increases ABT-737 lethality in diverse malignant cell types. These findings also show that the multidomain proapoptotic proteins Bax and Bak play important functional roles in ABT-737–mediated apoptosis, and that Bak activation is essential in potentiation of ABT-737 lethality by agents that down-regulate Mcl-1. Collectively, these findings suggest a novel therapeutic strategy targeting multiple arms of the apoptotic machinery. [Cancer Res 2007;67(7):2908–11]
Economic Sociology in the Next Decade and Beyond
Authors: Beamish Thomas D.
Published: April 2007

This article assesses “Economic Sociology in the Next Decade and Beyond.” In addressing this broad thematic, as it relates to what some have called the new economic sociology , the article notes the “legacy effect” that a polemic with conventional economic conceptualizations has had on the recent reemergence and shape of this field, the relationship that the predominate schools of thought have to one another and the centrifugal tendencies they currently exhibit in this field, and the relationship this field of study currently has to general sociological theories and research streams. The article expressly argues that it is essential to the current and future relevance of the new economic sociology that it seek to bridge key concepts and ideas across methodologically and substantively distinct subfoci within its purview; enhance the theoretical continuity between its findings and theoretical insights and those that explain more generic sociological processes; and more explicitly theorize the role of agency, materiality, and the place of inequality in economic contexts, especially markets, as these are currently undertheorized in this field of study.