bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of the Vascular Disrupting Agent ZD6126 on Interstitial Fluid Pressure and Cell Survival in Tumors
Authors: Skliarenko Julia V. , Lunt Sarah Jane , Gordon Maggie L. , Vitkin Alex , Milosevic Michael , Hill Richard P.
Published: February 2006

Interstitial fluid pressure (IFP) is elevated in tumors due to abnormal vasculature, lack of lymphatic drainage, and alterations in the tumor interstitium. ZD6126 is a tubulin-binding agent that selectively disrupts tumor vasculature resulting in tumor necrosis. This study examined the effect of ZD6126 on tumor IFP and the response of tumors with different IFP levels to ZD6126. Pretreatment IFP was measured using the wick-in-needle method in tumors (murine KHT-C and human CaSki) growing i.m. in the hind legs of mice. Mice were treated i.p. with a single dose of ZD6126 (100 or 200 mg/kg) and posttreatment IFP measurements were made. Blood flow imaging was conducted using Doppler optical coherence tomography, whereas oxygen partial pressure was measured using a fiber optic probe. Clonogenic assays were done to determine tumor cell survival. In KHT-C tumors, IFP dropped significantly at 1 hour posttreatment, returned to pretreatment values at 3 hours, and then declined to ∼25% of the pretreatment values by 72 hours. In CaSki tumors, the IFP decreased progressively, beginning at 1 hour, to ∼30% of pretreatment values by 72 hours. Clonogenic cell survival data indicated that ZD6126 was less effective in tumors with high IFP values (>25 mm Hg). Vascular disrupting agents, such as ZD6126, can affect IFP levels and initial IFP levels may predict tumor response to these agents. The higher cell survival in high IFP tumors may reflect greater microregional blood flow limitations in these tumors and reduced access of the drug to the target endothelial cells. (Cancer Res 2006; 66(4): 2074-80)
SKI-606 Decreases Growth and Motility of Colorectal Cancer Cells by Preventing pp60(c-Src)–Dependent Tyrosine Phosphorylation of β-Catenin and Its Nuclear Signaling
Authors: Coluccia Addolorata Maria Luce , Benati Daniela , Dekhil Hafedh , De Filippo Annamaria , Lan Cathy , Gambacorti-Passerini Carlo
Published: February 2006

Inhibition of deregulated protein tyrosine kinases represents an attractive strategy for controlling cancer growth. However, target specificity is an essential aim of this strategy. In this report, pp60(c-Src) kinase and β-catenin were found physically associated and constitutively activated on tyrosine residues in human colorectal cancer cells. The use of specific small-interfering RNAs (siRNA) validated pp60(c-Src) as the major kinase responsible for β-catenin tyrosine phosphorylation in colorectal cancer. Src-dependent activation of β-catenin was prevented by SKI-606, a novel Src family kinase inhibitor, which also abrogated β-catenin nuclear function by impairing its binding to the TCF4 transcription factor and its trans-activating ability in colorectal cancer cells. These effects were seemingly specific, as cyclin D1, a crucial β-catenin/TCF4 target gene, was also down-regulated by SKI-606 in a dose-dependent manner accounting, at least in part, for the reduced growth (IC50, 1.5-2.4 μmol/L) and clonogenic potential of colorectal cancer cells. Protein levels of β-catenin remained substantially unchanged by SKI-606, which promoted instead a cytosolic/membranous retention of β-catenin as judged by immunoblotting analysis of cytosolic/nuclear extracts and cell immunofluorescence staining. The SKI-606-mediated relocalization of β-catenin increased its binding affinity to E-cadherin and adhesion of colorectal cancer cells, with ensuing reduced motility in a wound healing assay. Interestingly, the siRNA-driven knockdown of β-catenin removed the effect of SKI-606 on cell-to-cell adhesion, which was associated with prolonged stability of E-cadherin protein in a pulse-chase experiment. Thus, our results show that SKI-606 operates a switch between the transcriptional and adhesive function of β-catenin by inhibiting its pp60(c-Src)–dependent tyrosine phosphorylation; this could constitute a new therapeutic target in colorectal cancer. (Cancer Res 2006; 66(4): 2279-86)
Embryonic Stem Cell–Derived Dendritic Cells Expressing Glypican-3, a Recently Identified Oncofetal Antigen, Induce Protective Immunity against Highly Metastatic Mouse Melanoma, B16-F10
Authors: Motomura Yutaka , Senju Satoru , Nakatsura Tetsuya , Matsuyoshi Hidetake , Hirata Shinya , Monji Mikio , Komori Hiroyuki , Fukuma Daiki , Baba Hideo , Nishimura Yasuharu
Published: February 2006

We have recently established a method to generate dendritic cells from mouse embryonic stem cells. By introducing exogenous genes into embryonic stem cells and subsequently inducing differentiation to dendritic cells (ES-DC), we can now readily generate transfectant ES-DC expressing the transgenes. A previous study revealed that the transfer of genetically modified ES-DC expressing a model antigen, ovalbumin, protected the recipient mice from a challenge with an ovalbumin-expressing tumor. In the present study, we examined the capacity of ES-DC expressing mouse homologue of human glypican-3, a recently identified oncofetal antigen expressed in human melanoma and hepatocellular carcinoma, to elicit protective immunity against glypican-3-expressing mouse tumors. CTLs specific to multiple glypican-3 epitopes were primed by the in vivo transfer of glypican-3-transfectant ES-DC (ES-DC-GPC3). The transfer of ES-DC-GPC3 protected the recipient mice from subsequent challenge with B16-F10 melanoma, naturally expressing glypican-3, and with glypican-3-transfectant MCA205 sarcoma. The treatment with ES-DC-GPC3 was also highly effective against i.v. injected B16-F10. No harmful side effects, such as autoimmunity, were observed for these treatments. The depletion experiments and immunohistochemical analyses suggest that both CD8+ and CD4+ T cells contributed to the observed antitumor effect. In conclusion, the usefulness of glypican-3 as a target antigen for antimelanoma immunotherapy was thus shown in the mouse model using the ES-DC system. Human dendritic cells expressing glypican-3 would be a promising means for therapy of melanoma and hepatocellular carcinoma. (Cancer Res 2006; 66(4): 2414-22)
Expression of p53 Enhances Selenite-Induced Superoxide Production and Apoptosis in Human Prostate Cancer Cells
Authors: Zhao Rui , Xiang Nong , Domann Frederick E. , Zhong Weixiong
Published: February 2006

Although the anticancer effects of selenium have been shown in clinical, preclinical, and laboratory studies, the underlying mechanism(s) remains unclear. Our previous study showed that sodium selenite induced LNCaP human prostate cancer cell apoptosis in association with production of reactive oxygen species, alteration of cell redox state, and mitochondrial damage. In the present study, we showed that selenite-induced apoptosis was superoxide mediated and p53 dependent via mitochondrial pathways. In addition, we also showed that superoxide production by selenite was p53 dependent. Our study showed that wild-type p53–expressing LNCaP cells were more sensitive to selenite-induced apoptosis than p53-null PC3 cells. Selenite treatment resulted in high levels of superoxide production in LNCaP cells but only low levels in PC3 cells. LNCaP cells also showed sequential increases in levels of phosphorylated p53 (serine 15), total p53, Bax, and p21Waf1 proteins following selenite treatment. The effects of selenite were suppressed by pretreatment with a synthetic superoxide dismutase mimic or by knockdown of p53 via RNA interference. LNCaP cells treated with selenite also showed p53 translocation to mitochondria, cytochrome c release into the cytosol, and activation of caspase-9. On the other hand, restoration of wild-type p53 expression in PC3 cells increased cellular sensitivity to selenite and resulted in increased superoxide production, caspase-9 activation, and apoptosis following selenite treatment. These results suggest that selenite induces apoptosis by producing superoxide to activate p53 and to induce p53 mitochondrial translocation. Activation of p53 in turn synergistically enhances superoxide production and apoptosis induced by selenite. (Cancer Res 2006; 66(4): 2296-304)
Multiple Oncogenic Changes (K-RASV12, p53 Knockdown,Mutant EGFRs, p16Bypass, Telomerase) Are Not Sufficient to Confer a Full Malignant Phenotype on Human Bronchial Epithelial Cells
Authors: Sato Mitsuo , Vaughan Melville B. , Girard Luc , Peyton Michael , Lee Woochang , Shames David S. , Ramirez Ruben D. , Sunaga Noriaki , Gazdar Adi F. , Shay Jerry W. , Minna John D.
Published: February 2006

We evaluated the contribution of three genetic alterations (p53 knockdown, K-RASV12, and mutant EGFR) to lung tumorigenesis using human bronchial epithelial cells (HBEC) immortalized with telomerase and Cdk4-mediated p16 bypass. RNA interference p53 knockdown or oncogenic K-RASV12 resulted in enhanced anchorage-independent growth and increased saturation density of HBECs. The combination of p53 knockdown and K-RASV12 further enhanced the tumorigenic phenotype with increased growth in soft agar and an invasive phenotype in three-dimensional organotypic cultures but failed to cause HBECs to form tumors in nude mice. Growth of HBECs was highly dependent on epidermal growth factor (EGF) and completely inhibited by EGF receptor (EGFR) tyrosine kinase inhibitors, which induced G1 arrest. Introduction of EGFR mutations E746-A750 del and L858R progressed HBECs toward malignancy as measured by soft agar growth, including EGF-independent growth, but failed to induce tumor formation. Mutant EGFRs were associated with higher levels of phospho-Akt, phospho–signal transducers and activators of transcription 3 [but not phospho-extracellular signal-regulated kinase (ERK) 1/2], and increased expression of DUSP6/MKP-3 phosphatase (an inhibitor of phospho-ERK1/2). These results indicate that (a) the HBEC model system is a powerful new approach to assess the contribution of individual and combinations of genetic alterations to lung cancer pathogenesis; (b) a combination of four genetic alterations, including human telomerase reverse transcriptase overexpression, bypass of p16/RB and p53 pathways, and mutant K-RASV12 or mutant EGFR, is still not sufficient for HBECs to completely transform to cancer; and (c) EGFR tyrosine kinase inhibitors inhibit the growth of preneoplastic HBEC cells, suggesting their potential for chemoprevention. (Cancer Res 2006; 66(4): 2116-28)
Protein Kinase B/Akt-Dependent Phosphorylation of Glycogen Synthase Kinase-3β in Irradiated Vascular Endothelium
Authors: Tan Jiahua , Geng Ling , Yazlovitskaya Eugenia M. , Hallahan Dennis E.
Published: February 2006

The vascular endothelium plays a critical role in the response of cancer to ionizing radiation. Activation of the phosphoinositide-3-kinase/Akt pathway is one initial signaling event in irradiated endothelial cells. Specifically, a low dose of ionizing radiation (3 Gy) induces phosphorylation of Akt at Ser473 in the vascular endothelium within minutes of irradiation. However, signaling events that are downstream of Akt have not been well defined. Here, we show that phosphorylation of the Akt downstream target glycogen synthase kinase-3β (GSK-3β) at Ser9 also occurred within minutes of exposure to ionizing radiation. In addition, ionizing radiation caused the dissociation of GSK-3β from the cell membrane, consistent with the inactivation of GSK-3β enzyme activity. Overexpression of the dominant negative mutant Akt attenuated GSK-3β phosphorylation at Ser9 and enhanced radiation-induced apoptosis. X-irradiated endothelial cells formed capillaries in both in vitro and in vivo models, whereas overexpression of the dominant negative mutant Akt inhibited capillary tubule formation. Studies using GSK-3β antagonists showed that GSK-3β activity was required for apoptosis in endothelial cells treated simultaneously with Akt antagonists and radiation. In mouse vascular models, radiation-induced microvascular destruction in response to Akt antagonists also required GSK-3β function. These data indicate that on exposure of vascular endothelium to ionizing radiation, activation of Akt signaling contributes to GSK-3β inhibition, which in turn promotes endothelial cell survival and capillary formation. Thus, pharmacologic regulation of Akt/GSK-3β signaling may present a new approach to the radiation response in the tumor microvasculature. (Cancer Res 2006; 66(4): 2320-7)
Integrin α4β1 Promotes Monocyte Trafficking and Angiogenesis in Tumors
Authors: Jin Hui , Su Jingmei , Garmy-Susini Barbara , Kleeman Jeanine , Varner Judy
Published: February 2006

Monocytes and macrophages extensively colonize solid tumors, where they are thought to promote tumor angiogenesis. Here, we show that integrin α4β1 (VLA4) promotes the invasion of tumors by myeloid cells and subsequent neovascularization. Antagonists of integrin α4β1, but not of other integrins, blocked the adhesion of monocytes to endothelium in vitro and in vivo as well as their extravasation into tumor tissue. These antagonists prevented monocyte stimulation of angiogenesis in vivo, macrophage colonization of tumors, and tumor angiogenesis. These studies indicate the usefulness of antagonists of integrin α4β1 in suppressing macrophage colonization of tumors and subsequent tumor angiogenesis. These studies further indicate that suppression of myeloid cell homing to tumors could be a useful supplementary approach to suppress tumor angiogenesis and growth. (Cancer Res 2006; 66(4):2146-52)
Identification of the IFITM Family as a New Molecular Marker in Human Colorectal Tumors
Authors: Andreu Pauline , Colnot Sabine , Godard Cécile , Laurent-Puig Pierre , Lamarque Dominique , Kahn Axel , Perret Christine , Romagnolo Béatrice
Published: February 2006

We analyzed the expression profiles of intestinal adenomas from a new murine familial adenomatous polyposis model (ApcΔ14/+) using suppression subtractive hybridization to identify novel diagnostic markers of colorectal carcinogenesis. We identified 18 candidate genes having increased expression levels in the adenoma. Subsequent Northern blotting, real-time reverse transcription-PCR, and in situ hybridization analysis confirmed their induction in β-catenin-activated epithelial cells of murine adenomas. We showed that most of the genes also have altered expression levels in human colonic adenomas and carcinomas. We focused on the IFITM genes that encode IFN-inducible transmembrane proteins. Serial analyses of gene expression levels revealed high levels of expression in early and late intestinal neoplasm in both mice and humans. Using a conditional mouse model of Apc inactivation and a human colon carcinoma cell line, we showed that IFITM gene expression is rapidly induced after activation of the β-catenin signaling. Using a large-scale analysis of human tumors, we showed that IFITM gene expression is significantly up-regulated specifically in colorectal tumors and thus may be a useful diagnostic tool in these tumors. (Cancer Res 2006; 66(4): 1949-55)
Role of Protein Kinase CK2 in the Regulation of Tumor Necrosis Factor–Related Apoptosis Inducing Ligand–Induced Apoptosis in Prostate Cancer Cells
Authors: Wang Guixia , Ahmad Kashif A. , Ahmed Khalil
Published: February 2006

Protein kinase CK2 (formerly casein kinase 2 or II) is a ubiquitous and highly conserved protein Ser/Thr kinase that plays diverse roles such as in cell proliferation and apoptosis. With respect to the latter, we originally showed that elevated CK2 could suppress various types of apoptosis in prostate cancer cells; however, the downstream pathways that respond to CK2 for mediating the suppression of apoptosis have not been fully elucidated. Here, we report studies on the role of CK2 in influencing activities associated with tumor necrosis factor–related ligand (TRAIL/Apo2-L)–mediated apoptosis in prostate carcinoma cells. To that end, we show that both androgen-insensitive (PC-3) and androgen-sensitive (ALVA-41) prostate cancer cells are sensitized to TRAIL by chemical inhibition of CK2 using its specific inhibitor 4,5,6,7-tetrabromobenzotriazole (TBB). Furthermore, we have shown that overexpression of CK2α using pcDNA6-CK2α protected prostatic cancer cells from TRAIL-mediated apoptosis by affecting various activities associated with this process. Thus, overexpression of CK2 resulted in the suppression of TRAIL-induced apoptosis via its effects on the activation of caspases, DNA fragmentation, and downstream cleavage of lamin A. In addition, the overexpression of CK2 blocked the mitochondrial apoptosis machinery engaged by TRAIL. These findings define the important role of CK2 in TRAIL signaling in androgen-sensitive and -insensitive prostatic carcinoma cells. Our data support the potential usefulness of anticancer strategies that may involve the combination of TRAIL and down-regulation of CK2. (Cancer Res 2006; 66(4): 2242-9)
Parathyroid Hormone–Related Protein Localization in Breast Cancers Predict Improved Prognosis
Authors: Henderson Michael A. , Danks Janine A. , Slavin John L. , Byrnes Graham B. , Choong Peter F.M. , Spillane John B. , Hopper John L. , Martin T. John
Published: February 2006

In a prospective study of 526 consecutive patients with operable breast cancer, the significance of positive parathyroid hormone–related protein (PTHrP) staining by immunohistology has been evaluated for a median of 10-year follow-up. Improved survival was observed for the 79% of tumors which stained positively for PTHrP [estimated univariate hazard ratio, 0.43; 95% confidence interval (95% CI), 0.30-0.62; P < 0.001]. Adjustments for N stage, progesterone receptor status, and log tumor size changed this estimate only slightly to 0.47 (95% CI, 0.63-0.69; P = 0.001). Patients with PTHrP-positive primary tumors were less likely to develop bone metastases (hazard ratio, 0.63; 95% CI, 0.41-0.98; P = 0.04). PTHrP status was associated with estrogen receptor (P = 0.01), progesterone receptor (P = 0.03), and menopausal status (P = 0.006) but was not significantly associated with tumor size, vascular invasion, tumor grade, or patient age. Of 19 patients requiring surgery for bone metastases, the primary cancers were PTHrP negative in seven, all but one of whom had PTHrP-positive bone metastases. All 12 patients with PTHrP-positive primary cancers also had positive bone metastases. We conclude that increased production of PTHrP by breast cancers confers on them a less invasive phenotype, an effect distinct from the bone resorption–stimulating action that favors bone metastasis. It is likely that the latter property is influenced by factors in the bone microenvironment. (Cancer Res 2006; 66(4): 2250-6)
Cancer Risk Assessment at the Atomic Level
Authors: Monteiro Alvaro N.A. , Couch Fergus J.
Published: February 2006

A flurry of articles on the structure of different domains of BRCA1 and BRCA2 have not only shed light on the biology of these proteins but have also raised hopes that these data could eventually be used to infer cancer association for a large number of inherited missense mutations whose effect on protein function is unclear. (Cancer Res 2006; 66(4): 1897-9)
3-Methylcholanthrene and Other Aryl Hydrocarbon Receptor Agonists Directly Activate Estrogen Receptor α
Authors: Abdelrahim Maen , Ariazi Eric , Kim Kyounghyun , Khan Shaheen , Barhoumi Rola , Burghardt Robert , Liu Shengxi , Hill Denise , Finnell Richard , Wlodarczyk Bogdan , Jordan V. Craig , Safe Stephen
Published: February 2006

3-Methylcholanthrene (3MC) is an aryl hydrocarbon receptor (AhR) agonist, and it has been reported that 3MC induces estrogenic activity through AhR-estrogen receptor α (ERα) interactions. In this study, we used 3MC and 3,3′,4,4′,5-pentachlorobiphenyl (PCB) as prototypical AhR ligands, and both compounds activated estrogen-responsive reporter genes/gene products (cathepsin D) in MCF-7 breast cancer cells. The estrogenic responses induced by these AhR ligands were inhibited by the antiestrogen ICI 182780 and by the transfection of a small inhibitory RNA for ERα but were not affected by the small inhibitory RNA for AhR. These results suggest that 3MC and PCB directly activate ERα, and this was confirmed in a competitive ERα binding assay and in a fluorescence resonance energy transfer experiment in which PCB and 3MC induced CFP-ERα/YFP-ERα interactions. In a chromatin immunoprecipitation assay, PCB and 3MC enhanced ERα (but not AhR) association with the estrogen-responsive region of the pS2 gene promoter. Moreover, in AhR knockout mice, 3MC increased uterine weights and induced expression of cyclin D1 mRNA levels. These results show that PCB and 3MC directly activate ERα-dependent transactivation and extend the number of ligands that activate both AhR and ERα. (Cancer Res 2006; 66(4): 2459-67)
Cancer Stem Cells: An Old Idea—A Paradigm Shift
Authors: Wicha Max S. , Liu Suling , Dontu Gabriela
Published: February 2006

Although the concept that cancers arise from “stem cells” or “germ cells” was first proposed about 150 years ago, it is only recently that advances in stem cell biology have given new impetus to the “cancer stem cell hypothesis.” Two important related concepts of this hypothesis are that (a) tumors originate in either tissue stem cells or their immediate progeny through dysregulation of the normally tightly regulated process of self-renewal. As a result of this, (b) tumors contain a cellular subcomponent that retains key stem cell properties. These properties include self-renewal, which drives tumorigenesis, and differentiation albeit aberrant that contributes to cellular heterogeneity. Recent experimental evidence in a variety of tumors has lent strong support to the cancer stem cell hypothesis that represents a paradigm shift in our understanding of carcinogenesis and tumor cell biology. This hypothesis has fundamental implications for cancer risk assessment, early detection, prognostication, and prevention. Furthermore, the current development of cancer therapeutics based on tumor regression may have produced agents that kill differentiated tumor cells while sparing the rare cancer stem cell population. The development of more effective cancer therapies may thus require targeting this important cell population. (Cancer Res 2006; 66(4): 1883-90)
p53 Regulates Cellular Resistance to Complement Lysis through Enhanced Expression of CD59
Authors: Donev Rossen M. , Cole Duncan S. , Sivasankar Baalasubramanian , Hughes Timothy R. , Morgan B. Paul
Published: February 2006

It has been recently hypothesized that the CD59 gene has two putative p53-responsive elements that may be involved in defense of host cells from damage by the complement system in inflammation. Here we have examined the roles of these putative p53-binding sequences within the CD59 gene in regulation of CD59 expression. We have shown that both of these potential responsive elements bind p53 in vitro. Knocking down expression of p53 using small interfering RNA led to a 6-fold decrease in CD59 protein expression in HeLa cells. We have previously observed a decrease of CD59 in camptothecin-induced apoptotic IMR32 cells, whereas expression was increased in the surviving fraction compared with untreated cells. Here, we have shown that these changes are associated with altered expression levels and acetylation status of p53. We have also shown that acetylation status of p53 regulates CD59 expression on cells exposed to inflammatory cytokines to model inflammation. Our data suggest that p53 and in vivo positive/negative regulators of p53 could be used to modulate susceptibility of tumor cells to complement lysis in chemotherapy. (Cancer Res 2006; 66(4): 2451-8)
Role of the CXCL12/CXCR4 Axis in Peritoneal Carcinomatosis of Gastric Cancer
Authors: Yasumoto Kazuo , Koizumi Keiichi , Kawashima Atsuhiro , Saitoh Yurika , Arita Yoshihisa , Shinohara Kanna , Minami Takayuki , Nakayama Takashi , Sakurai Hiroaki , Takahashi Yutaka , Yoshie Osamu , Saiki Ikuo
Published: February 2006

Peritoneal carcinomatosis is a frequent cause of death in patients with advanced gastric carcinoma. Because chemokines are now considered to play an important role in the metastasis of various malignancies, we hypothesized that they may be involved in the development of peritoneal carcinomatosis by gastric carcinoma. Human gastric carcinoma cell lines, which were all highly efficient in generating malignant ascites in nude mice upon i.p. inoculation, selectively expressed CXCR4 mRNA and protein. In particular, NUGC4 cells expressed CXCR4 mRNA at high levels and showed vigorous migratory responses to its ligand CXCL12. CXCL12 enhanced proliferation and rapid increases in phosphorylation of protein kinase B/Akt and extracellular signal-regulated kinase of NUGC4 cells. We also showed that AMD3100 (a specific CXCR4 antagonist) effectively reduced tumor growth and ascitic fluid formation in nude mice inoculated with NUGC4 cells. Additionally, we examined human clinical samples. Malignant ascitic fluids from patients with peritoneal carcinomatosis contained high concentrations of CXCL12 (4.67 ng/mL). Moreover, immunohistochemical analysis showed that 22 of 33 primary gastric tumors with peritoneal metastasis were positive for CXCR4 expression (67%), whereas only 4 of 16 with other distant metastasis were positive (25%). Notably, 22 of 26 CXCR4-expressing primary tumors developed peritoneal metastases (85%). CXCR4 positivity of primary gastric carcinomas significantly correlated with the development of peritoneal carcinomatosis (P < 0.001). Collectively, our results strongly suggest that the CXCR4/CXC12 axis plays an important role in the development of peritoneal carcinomatosis from gastric carcinoma. Thus, CXCR4 may be a potential therapeutic target for peritoneal carcinomatosis of gastric carcinoma. (Cancer Res 2006; 66(4): 2181-7)
Identifying Cancer Stem Cells in Solid Tumors: Case Not Proven
Authors: Hill Richard P.
Published: February 2006

Building on studies of leukemia, a number of recent articles have reported data suggesting that cancer stem cells could be isolated from solid human cancers. Some of these reports have speculated that the isolation of these cells will allow the identification of the specific molecular properties that can be targeted for therapeutic purposes. Although previous work with animal model systems also suggests the presence of stem cells in solid tumors, there remain many uncertainties, both theoretical and technical, about the interpretation of the current results. The case that a small proportion of cells in solid tumors are specific cancer stem cells and that these cells can be successfully identified and isolated has not yet been proven. (Cancer Res 2006; 66(4): 1891-6)
Dominant-Stable β-Catenin Expression Causes Cell Fate Alterations and Wnt Signaling Antagonist Expression in a Murine Granulosa Cell Tumor Model
Authors: Boerboom Derek , White Lisa D. , Dalle Sophie , Courty José , Richards JoAnne S.
Published: February 2006

Wnt/β-catenin signaling is normally involved in embryonic development and tissue homeostasis, and its misregulation leads to several forms of cancer. We have reported that misregulated Wnt/β-catenin signaling occurs in ovarian granulosa cell tumors (GCT) and have created the Catnbflox(ex3)/+;Amhr2cre/+ mouse model, which expresses a dominant-stable mutant of β-catenin in granulosa cells and develops late-onset GCT. To study the mechanisms leading to GCT development, gene expression analysis was done using microarrays comparing Catnbflox(ex3)/+;Amhr2cre/+ ovaries bearing pretumoral lesions with control ovaries. Overexpressed genes identified in Catnbflox(ex3)/+;Amhr2cre/+ ovaries included the Wnt/β-catenin signaling antagonists Wif1, Nkd1, Dkk4, and Axin2, consistent with the induction of negative feedback loops that counteract uncontrolled Wnt/β-catenin signaling. Expression of the antagonists was localized to cells forming the pretumoral lesions but not to normal granulosa cells. Microarray analyses also revealed the ectopic expression of bone markers, including Ibsp, Cdkn1c, Bmp4, and Tnfrsf11b, as well as neuronal/neurosecretory cell markers, such as Cck, Amph, Pitx1, and Sp5. Increased expression of the gene encoding the cytokine pleiotrophin was also found in Catnbflox(ex3)/+;Amhr2cre/+ ovaries and GCT but was not associated with increased serum pleiotrophin levels. In situ hybridization analyses using GCT from Catnbflox(ex3)/+;Amhr2cre/+ mice revealed that Wnt/β-catenin antagonists and neuronal markers localized to a particular cell population, whereas the bone markers localized to a distinct cell type associated with areas of osseous metaplasia. Together, these results suggest that misregulated Wnt/β-catenin signaling alters the fate of granulosa cells and that the GCT that arise in Catnbflox(ex3)/+;Amhr2cre/+ mice result from the clonal expansion of metaplastic cells. (Cancer Res 2006; 66(4): 1964-73)
The Tumor Suppressor Smad4 Is Required for Transforming Growth Factor β–Induced Epithelial to Mesenchymal Transition and Bone Metastasis of Breast Cancer Cells
Authors: Deckers Martine , van Dinther Maarten , Buijs Jeroen , Que Ivo , Löwik Clemens , van der Pluijm Gabri , ten Dijke Peter
Published: February 2006

Transforming growth factor β (TGF-β) can act as suppressor and promoter of cancer progression. Intracellular Smad proteins (i.e., receptor regulated Smads and common mediator Smad4) play a pivotal role in mediating antimitogenic and proapoptotic effects of TGF-β, but their function in TGF-β-induced invasion and metastasis is unclear. Here, we have investigated the role of Smad4 in a cellular and mouse model for TGF-β-induced breast cancer progression. Consistent with its tumor suppressor function, specific silencing of Smad4 in NMuMG mammary gland epithelial cells using small hairpin RNA (shRNA)–expressing RNAi vectors strongly mitigated TGF-β-induced growth inhibition and apoptosis. Smad4 knockdown also potently inhibited TGF-β-induced epithelial to mesenchymal transition of NMuMG cells as measured by morphologic transformation from epithelial to fibroblast-like cells, formation of stress fibers, inhibition of E-cadherin expression, and gain of expression of various mesenchymal markers. Furthermore, we show that knockdown of Smad4 in MDA-MB-231 breast cancer cells strongly inhibited the frequency of bone metastasis in nude mice by 75% and significantly increased metastasis-free survival. Communication of MDA-MB-231 cells with the bone microenvironment, which is needed for optimal tumor cell growth and metastasis, may be affected in Smad4 knockdown cells as TGF-β-induced expression of interleukin 11 was attenuated on Smad4 knockdown. Taken together, our results show that Smad4 plays an important role in both tumor suppression and progression of breast cancer cells. (Cancer Res 2006; 66(4): 2202-9)
LXR Activation Reduces Proinflammatory Cytokine Expression in Human CD4-Positive Lymphocytes
Authors: Walcher Daniel , Kümmel Andreas , Kehrle Bettina , Bach Helga , Grüb Miriam , Durst Renate , Hombach Vinzenz , Marx Nikolaus
Published: February 2006

Background—

CD4-positive lymphocytes, the major T-cell population in human atheroma, mainly secrete Th-1-type proinflammatory cytokines, like interferon (IFN)γ, tumor necrosis factor (TNF)α, and interleukin (IL)-2, thus promoting atherogenesis. Recent data suggest that the nuclear transcription factors liver X receptor-alpha and liver X receptor-beta (LXRα and LXRβ) limit plaque formation in animal models by modulating macrophage function. Still, the role of LXRs in CD4-positive lymphocytes is currently unexplored.

Methods and Results—

Human CD4-positive lymphocytes express LXRα and LXRβ mRNA and protein. Activation of CD4-positive cells by anti-CD3 mAbs, anti-CD3/CD28 mAbs, as well as PMA/ionomycin significantly increased Th1-cytokine mRNA and protein expression. Treatment with the LXR activator T0901317 reduced this increase of IFNγ, TNFα, and IL-2 in a concentration-dependent manner with a maximum at 1 μmol/L T0901317. Transient transfection assays revealed an inhibition of IFNγ promoter activity by T0901317 as the underlying molecular mechanism. Such anti-inflammatory actions were also evident in cell–cell interactions with medium conditioned by T0901317-treated CD4-positive cells attenuating human monocyte CD64 expression.

Conclusions—

Human CD4-positive lymphocytes express both LXRα and LXRβ, and LXR activation can reduce Th-1 cytokine expression in these cells. These data provide new insight how LXR activators might modulate the inflammatory process in atherogenesis and as such influence lesion development.
Synthetic Retinoid Am80 Reduces Scavenger Receptor Expression and Atherosclerosis in Mice by Inhibiting IL-6
Authors: Takeda Norifumi , Manabe Ichiro , Shindo Takayuki , Iwata Hiroshi , Iimuro Satoshi , Kagechika Hiroyuki , Shudo Koichi , Nagai Ryozo
Published: February 2006

Background—Macrophage scavenger receptors facilitate the uptake of modified low-density lipoprotein (LDL), formation of foam cells, and development of atherosclerosis. Given that proinflammatory cytokines, including IL-6, can modulate the macrophage foaming process, the aim of the present study was to determine whether the synthetic retinoic acid receptor-α/β-specific agonist Am80, which is also an IL-6 inhibitor, can modulate macrophage lipid accumulation and foam cell formation.

Methods and Results—Am80 suppressed IL-6 production induced by 12-myristate 13-acetate (PMA) or angiotensin II in mouse Raw264 macrophages. It also suppressed expression of the 2 major scavenger receptors (scavenger receptor-A [SR-A] and CD36), in part by inhibiting IL-6, and inhibited macrophage foam cell formation. Systemic administration of Am80 led to reductions in the areas of atherosclerotic lesions and foam cell accumulation in the aortas ofapolipoprotein E (apoE)-deficient mice and reduced serum concentrations of IL-6 and IL-1β without affecting body weights, serum lipid profiles or IL-10 levels.

Conclusions—Am80 suppresses scavenger receptor expression and macrophage foam cell formation in vitro and prevents atherogenesis inapoE-deficient mice in vivo. This suggests Am80 is a novel candidate agent that could be highly useful in the prevention and treatment of atherosclerosis.
The Serum- and Glucocorticoid-Inducible Kinase Sgk-1 Is Involved in Pulmonary Vascular Remodeling
Authors: BelAiba Rachida S. , Djordjevic Talija , Bonello Steve , Artunc Ferruh , Lang Florian , Hess John , Görlach Agnes
Published: February 2006

The stress-responsive serum- and glucocorticoid-inducible kinase Sgk-1 is involved in osmoregulation and cell survival and may contribute to fibrosis and hypertension. However, the function of Sgk-1 in vascular remodeling and thrombosis, 2 major determinants of pulmonary hypertension (PH), has not been elucidated. We investigated the role of Sgk-1 in thrombin signaling and tissue factor (TF) expression and activity in pulmonary artery smooth muscle cells (PASMC). Thrombin increased Sgk-1 activity and mRNA and protein expression. H
2
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2
similarly induced Sgk-1 expression. Antioxidants, dominant-negative Rac, and depletion of the NADPH oxidase subunit p22phox diminished thrombin-induced Sgk-1 expression. Inhibition of p38 mitogen-activated protein kinase, phosphatidylinositol 3-kinase, and phosphoinositide-dependent kinase-1 prevented thrombin-induced Sgk-1 expression. Thrombin or Sgk-1 overexpression enhanced TF expression and procoagulant activity, whereas TF upregulation by thrombin was diminished by kinase-deficient Sgk-1 and was not detectable in fibroblasts from mice deficient in sgk-1 (sgk1
−/−
). Similarly, dexamethasone treatment failed to induce TF expression and activity in lung tissue from sgk1
−/−
mice. Transcriptional induction of TF by Sgk-1 was mediated through nuclear factor κB. Finally, Sgk-1 and TF proteins were detected in the media of remodeled pulmonary vessels associated with PH. These data show that thrombin potently induces Sgk-1 involving NADPH oxidases, phosphatidylinositol 3-kinase, p38 mitogen-activated protein kinase, and phosphoinositide-dependent kinase-1, and that activation of nuclear factor κB by Sgk-1 mediates TF expression and activity by thrombin. Because enhanced procoagulant activity can promote pulmonary vascular remodeling, and Sgk-1 and TF were present in the media of remodeled pulmonary vessels, this pathway may play a critical role in vascular remodeling in PH.
Embryonic Growth-Associated Protein Is One Subunit of a Novel N-Terminal Acetyltransferase Complex Essential for Embryonic Vascular Development
Authors: Wenzlau Janet M. , Garl Pamela J. , Simpson Peter , Stenmark Kurt R. , West James , Artinger Kristin B. , Nemenoff Raphael A. , Weiser-Evans Mary C.M.
Published: February 2006

N-terminal protein acetylation, catalyzed by N-terminal acetyltransferases (NATs) recognizing distinct N-terminal sequences, is gaining recognition as an essential regulator of normal cell function, but little is known of its role in vertebrate development. We previously cloned a novel gene, embryonic growth-associated protein (EGAP), the expression of which is associated with rapid vascular smooth muscle cell proliferation during development. We show herein EGAP is the mammalian/
zebrafish
homologue of yeast Mak10p, one subunit of the yeast NatC complex, and describe the cloning of its binding partners Mak3 and Mak31. The EGAP NAT forms a functional complex in mammalian cells, is evolutionarily conserved, and developmentally regulated. It is widely but not ubiquitously expressed during early
zebrafish
development but undetectable in later developmental stages. We demonstrate EGAP- and Mak3-deficient
zebrafish
fail to develop because of, in part, decreased cell proliferation, increased apoptosis, and poor blood vessel formation contributing to embryonic lethality. We examined the role of target of rapamycin (TOR), a highly conserved protein kinase controlling cell growth, as a physiological target of EGAP NAT acetylation. Compared with controls, TOR expression and signaling is significantly reduced in EGAP morphants. Pharmacological inhibition of TOR with rapamycin phenocopied the EGAP morpholino oligonucleotide-induced growth and vessel defects. Overexpression of constitutively active TOR rescued EGAP morphants, suggesting TOR is a direct or indirect endogenous substrate of the EGAP NAT complex. These data suggest the EGAP NAT complex is an essential regulatory enzyme controlling the function of a subset of proteins required for embryonic growth control and vessel development.
Preeclampsia and the Risk of Ischemic Stroke Among Young Women
Authors: Brown David W. , Dueker Nicole , Jamieson Denise J. , Cole John W. , Wozniak Marcella A. , Stern Barney J. , Giles Wayne H. , Kittner Steven J.
Published: February 2006

Background and Purpose—

Preeclampsia is a pregnancy-specific systemic syndrome of unknown cause that affects 3% to 8% of pregnancies in the United States. Although preeclampsia is known to be an important risk factor for pregnancy-associated stroke, few data exist with regard to its association with stroke not occurring during pregnancy or the postpartum period.

Methods—

Using data from the Stroke Prevention in Young Women Study (SPYW), a population-based case-control study of risk factors for ischemic stroke in women aged 15 to 44 years (recruitment period: 1992 to 1996, SPYW-1; 2001 to 2003, SPYW-2), we examined the independent association between a history of preeclampsia and the likelihood of ischemic stroke. Odds ratios (ORs) and 95% CIs were estimated using logistic regression. Cases (n=261) were women with stroke in the greater Baltimore-Washington area, and controls (n=421) were women free of a history of stroke identified by random digit dialing. Women who were pregnant at the time of stroke, those whose stroke occurred within 42 days postpartum, and nulligravida women were excluded from the analysis.

Results—

The prevalence of preeclampsia among cases and controls was 15% (SPYW-1: 16%; SPYW-2: 15%) and 10% (SPYW-1: 10%; SPYW-2: 11%), respectively. Preeclampsia was associated with an increased likelihood of ischemic stroke (crude OR: 1.59; 95% CI: 1.00 to 2.52). After multivariable adjustment for age, race, education, and number of pregnancies, women with a history of preeclampsia were 60% more likely to have a nonpregnancy-related ischemic stroke than those without a history of preeclampsia (OR: 1.63; 95% CI: 1.02 to 2.62). Similar patterns were observed for women who reported symptoms of preeclampsia (elevated blood pressure and proteinuria).

Conclusion—

These results suggest an association between a history of preeclampsia and ischemic stroke remote from pregnancy. If these results are confirmed in other studies, evaluation of the importance of targeting women with preeclampsia for close risk factor monitoring and control beyond the postpartum period may be warranted.
Complex by Design
Authors: Boyd Donald J. , Grossman Pam , Lankford Hamilton , Loeb Susanna , Michelli Nicholas M. , Wyckoff Jim
Published: February 2006

New York City represents a microcosm of the changes that are shaking the very foundations of teacher education in this country. In their efforts to find teachers for hard-to-staff schools by creating multiple pathways into teaching, districts from New York City to Los Angeles are in the midst of what amounts to a national experiment in how best to recruit, prepare, and retain teachers. This article provides an overview of a research project that examines features of these different pathways into teaching in New York City schools and the impact of these features on where teachers teach, how long they remain in the classroom, and student achievement in reading and math as measured by value-added analyses. The article provides both a conceptual framework for the study and a discussion of some of the methodological challenges involved in such research, including problems of selection bias, difficulties in documenting programmatic features, and challenges of estimating teacher effects on student achievement.
Views of Disability in the United States and Singapore
Authors: Verbrugge Lois M. , Mehta Kalyani K. , Wagenfeld-Heintz Ellen
Published: February 2006

How do older people with disabilities feel about assistance? What do “independence,” “dependence,” and “disability” mean to them? The authors interviewed 34 American and 30 Singaporean people aged 70 years and older and compared their responses using quantitative and qualitative analyses. The U.S. seniors insisted on being in charge of their daily lives with minimal help of any kind. The Singaporeans received family help daily but felt that they were a burden and yearned for more personal freedom. In both countries, independence meant receiving no personal help for tasks or having personal autonomy. Dependence did not necessarily refer to the opposite situation. The Americans had broad criteria for a “person with disability”; the Singaporeans had narrow criteria. Singaporeans expressed great empathy for persons with disabilities, whereas Americans evaluated society's progress concerning them. Common research concepts appear to have different embedded cultural meanings in the two societies.
The pathogenesis of childhood anxiety disorders: Considerations from a developmental psychopathology perspective
Authors: Muris Peter
Published: February 2006

Anxiety disorders are among the most prevalent psychiatric problems in children and adolescents. The present article summarizes the main evidence that has accumulated on the pathogenesis of childhood anxiety disorders during the past two decades. Various risk and vulnerability factors (e.g., genetics, behavioral inhibition, disgust sensitivity, negative life events, family influences), protective factors (e.g., effortful control, perceived control), and maintaining factors (e.g., avoidance, cognitive biases) will be discussed. The information will be described in terms of a developmental psychopathology perspective, which assumes that (a) most forms of psychopathology are the result of multiple causal influences; (b) both successful and unsuccessful adaptation are important for understanding the origins of psychopathology; and (c) psychopathology occurs in a developing organism.
Subtypes of aggressive behaviors: A developmental perspective
Authors: Vitaro Frank , Brendgen Mara , Barker Edward D.
Published: February 2006

Aggressive behaviors in children and adolescents have undergone important conceptual and definitional modifications in the past two decades. In particular, subtypes of aggression have been proposed that separate the form and the function of the aggressive behaviors (i.e., social vs. physical aggression; reactive vs. proactive aggression). Moreover, new methodological tools have been developed to examine the developmental course of these subtypes, as well as their correlates. These conceptual and methodological innovations, in turn, have introduced new views of the development of aggressive behaviors. These “new views” contrast with more traditional perspectives about the evolution of aggressive behaviors from infancy to young adulthood, particularly with respect to the existence of individuals who begin to become aggressive by adolescence only. This article gives an overview of these definitional, conceptual, and methodological innovations. It also tries to reconcile different views about the development of aggressive behaviors from infancy through early adulthood. Theoretical and practical/clinical implications are also reviewed. The conclusion describes an integrative framework and identifies possible areas of research for the future.
Translation of research into interventions
Authors: Lochman John E.
Published: February 2006

This article discusses distinct ways in which research plays pivotal roles in the development, evaluation, refinement and dissemination of interventions for children and adolescents. A key challenge in interventions for high-risk children is to identify screening criteria for risk status. Longitudinal research is essential in creating a screening system with adequate sensitivity and specificity. Research-based developmental models should provide the framework for interventions as they are developed. These models can be then tested with the interventions, and ongoing developmental research can lead to a series of refinements of the interventions. Research can also provide essential information about who the programs succeed with and who they do not, and a newer phase of intervention research can rigorously identify factors which can bridge the “research-to-practice” gap, maximizing the effectiveness of interventions when they are disseminated into real-world settings.
Conducting policy-relevant developmental psychopathology research
Authors: Petersen Anne C.
Published: February 2006

Policy, defined broadly to include public policy as well as institutional or organizational policy, is useful for sustaining change in human development and its contexts and systems. The role for developmental psychopathology research in policy analysis and policy making is discussed. To assure that developmental psychopathology research is useful for policy (or practice) requires rigorous strategic thinking, commonly called “systems thinking”. Systems thinking is described and its usefulness tested with a specific example of human development change - that of delinquency career crime prevention. Policy implications are then drawn from the example and generalized to broader human developmental change.