bluuebunny/crossref_metadata_2025 huggingface dataset:
Dietary Genistein Inhibits Metastasis of Human Prostate Cancer in Mice
Authors: Lakshman Minalini , Xu Li , Ananthanarayanan Vijayalakshmi , Cooper Joshua , Takimoto Chris H. , Helenowski Irene , Pelling Jill C. , Bergan Raymond C.
Published: March 2008

Dietary genistein has been linked to lower prostate cancer (PCa) mortality. Metastasis is the ultimate cause of death from PCa. Cell detachment and invasion represent early steps in the metastatic cascade. We had shown that genistein inhibits PCa cell detachment and cell invasion in vitro. Genistein-mediated inhibition of activation of focal adhesion kinase (FAK) and of the p38 mitogen-activated protein kinase (MAPK)–heat shock protein 27 (HSP27) pathway has been shown by us to regulate PCa cell detachment and invasion effects, respectively. To evaluate the antimetastatic potential of genistein, we developed an animal model suited to evaluating antimetastatic drug efficacy. Orthotopically implanted human PC3-M PCa cells formed lung micrometastasis by 4 weeks in >80% of inbred athymic mice. Feeding mice dietary genistein before implantation led to blood concentrations similar to those measured in genistein-consuming men. Genistein decreased metastases by 96%, induced nuclear morphometric changes in PC3-M cells indicative of increased adhesion (i.e., decreased detachment) but did not alter tumor growth. Genistein increased tumor levels of FAK, p38 MAPK, and HSP27 “promotility” proteins. However, the ratio of phosphorylated to total protein trended downward, indicating a failure to increase relative amounts of activated protein. This study describes a murine model of human PCa metastasis well suited for testing antimetastatic drugs. It shows for the first time that dietary concentrations of genistein can inhibit PCa cell metastasis. Increases in promotility proteins support the notion of cellular compensatory responses to antimotility effects induced by therapy. Studies of antimetastatic efficacy in man are warranted and are under way. [Cancer Res 2008;68(6):2024–32]
NOTCH3 Signaling Pathway Plays Crucial Roles in the Proliferation of ErbB2-Negative Human Breast Cancer Cells
Authors: Yamaguchi Noritaka , Oyama Tetsunari , Ito Emi , Satoh Hitoshi , Azuma Sakura , Hayashi Mitsuhiro , Shimizu Ken , Honma Reiko , Yanagisawa Yuka , Nishikawa Akira , Kawamura Mika , Imai Jun-ichi , Ohwada Susumu , Tatsuta Kuniaki , Inoue Jun-ichiro , Semba Kentaro , Watanabe Shinya
Published: March 2008

ErbB2-negative breast tumors represent a significant therapeutic hurdle because of a lack of effective molecular targets. Although NOTCH proteins are known to be involved in mammary tumorigenesis, the functional significance of these proteins in ErbB2-negative breast tumors is not clear. In the present study, we examined the expression of activated NOTCH receptors in human breast cancer cell lines, including ErbB2-negative and ErbB2-positive cell lines. Activated NOTCH1 and NOTCH3 proteins generated by γ-secretase were detected in most of the cell lines tested, and both proteins activated CSL-mediated transcription. Down-regulation of NOTCH1 by RNA interference had little or no suppressive effect on the proliferation of either ErbB2-positive or ErbB2-negative cell lines. In contrast, down-regulation of NOTCH3 significantly suppressed proliferation and promoted apoptosis of the ErbB2-negative tumor cell lines. Down-regulation of NOTCH3 did not have a significant effect on the ErbB2-positive tumor cell lines. Down-regulation of CSL also suppressed the proliferation of ErbB2-negative breast tumor cell lines, indicating that the NOTCH-CSL signaling axis is involved in cell proliferation. Finally, NOTCH3 gene amplification was detected in a breast tumor cell line and one breast cancer tissue specimen even though the frequency of NOTCH3 gene amplification was low (<1%). Taken together, these findings indicate that NOTCH3-mediated signaling rather than NOTCH1-mediated signaling plays an important role in the proliferation of ErbB2-negative breast tumor cells and that targeted suppression of this signaling pathway may be a promising strategy for the treatment of ErbB2-negative breast cancers. [Cancer Res 2008;68(6):1881–8]
PTEN Has Tumor-Promoting Properties in the Setting of Gain-of-Function p53 Mutations
Authors: Li Yunqing , Guessous Fadila , Kwon Sherwin , Kumar Manish , Ibidapo Opeyemi , Fuller Lauren , Johnson Elizabeth , Lal Bachchu , Hussaini Isa , Bao Yongde , Laterra John , Schiff David , Abounader Roger
Published: March 2008

We show, for the first time, that the tumor suppressor PTEN can have tumor-promoting properties. We show that PTEN acquires these unexpected properties by enhancing gain-of-function mutant p53 (mut-p53) protein levels. We find that PTEN restoration to cells harboring mut-p53 leads to induction of G1-S cell cycle progression and cell proliferation and to inhibition of cell death. Conversely, PTEN inhibition in cells expressing wild-type PTEN and mut-p53 leads to inhibition of cell proliferation and inhibition of in vivo tumor growth. We show the dependency of the tumor-promoting effects of PTEN on mut-p53 by showing that knockdown of mut-p53 expression inhibits or reverses the tumor-promoting effects of PTEN. Mechanistically, we show that PTEN expression enhances mut-p53 protein levels via inhibition of mut-p53 degradation by Mdm2 and possibly also via direct protein binding. These findings describe a novel function of PTEN and have important implications for experimental and therapeutic strategies that aim at manipulating PTEN or p53 in human tumors. They suggest that the mutational status of PTEN and p53 should be considered to achieve favorable therapeutic outcomes. The findings also provide an explanation for the low frequency of simultaneous mutations of PTEN and p53 in human cancer. [Cancer Res 2008;68(6):1723–31]
Lipid Bodies Are Reservoirs of Cyclooxygenase-2 and Sites of Prostaglandin-E2 Synthesis in Colon Cancer Cells
Authors: Accioly Maria T. , Pacheco Patricia , Maya-Monteiro Clarissa M. , Carrossini Nina , Robbs Bruno K. , Oliveira Silvia S. , Kaufmann Cristiane , Morgado-Diaz José A. , Bozza Patricia T. , Viola João P.B.
Published: March 2008

Lipid bodies (lipid droplets) are emerging as dynamic organelles involved in lipid metabolism and inflammation. Increased lipid body numbers have been described in tumor cells; however, its functional significance in cancer has never been addressed. Here, we showed increased number of lipid bodies in tumor tissues from patients with adenocarcinoma of colon submitted to surgical resection when compared with an adjacent normal tissue. Accordingly, increased numbers of lipid bodies were observed in human colon adenocarcinoma cell lines and in a H-rasV12–transformed intestinal epithelial cell line (IEC-6 H-rasV12) compared with nontransformed IEC-6 cells. The functions of lipid bodies in eicosanoid synthesis in cancer cells were investigated. CACO-2 cells have increased expression of cyclooxygenase-2 (COX-2) when compared with IEC-6 cells. We showed by immunolocalization that, in addition to perinuclear stain, COX-2 and prostaglandin E (PGE) synthase present punctate cytoplasmic localizations that were concordant with adipose differentiation–related protein–labeled lipid bodies. The colocalization of COX-2 at lipid bodies was confirmed by immunoblot of subcellular fractionated cells. Direct localization of PGE2 at its synthesis locale showed that lipid bodies are sources of eicosanoids in the transformed colon cancer cells. Treatment with either aspirin or the fatty acid synthase inhibitor C75 significantly reduced the number of lipid bodies and PGE2 production in CACO-2 and in IEC-6 H-rasV12 cells with effects in cell proliferation. Together, our results showed that lipid bodies in colon cancer cells are dynamic and functional active organelles centrally involved in PGE2 synthesis and may potentially have implications in the pathogenesis of adenocarcinoma of colon. [Cancer Res 2008;68(6):1732–40]
Human Tumor Antigens Tn and Sialyl Tn Arise from Mutations inCosmc
Authors: Ju Tongzhong , Lanneau Grainger S. , Gautam Tripti , Wang Yingchun , Xia Baoyun , Stowell Sean R. , Willard Margaret T. , Wang Wenyi , Xia Jonathan Y. , Zuna Rosemary E. , Laszik Zoltan , Benbrook Doris M. , Hanigan Marie H. , Cummings Richard D.
Published: March 2008

Neoplastic lesions typically express specific carbohydrate antigens on glycolipids, mucins, and other glycoproteins. Such antigens are often under epigenetic control and are subject to reversion and loss upon therapeutic selective pressure. We report here that two of the most common tumor-associated carbohydrate antigens, Tn and sialyl Tn (STn), result from somatic mutations in the gene Cosmc that encodes a molecular chaperone required for formation of the active T-synthase. Diverse neoplastic lesions, including colon cancer and melanoma-derived cells lines, expressed both Tn and STn antigen due to loss-of-function mutations in Cosmc. In addition, two human cervical cancer specimens that showed expression of the Tn/STn antigens were also found to have mutations in Cosmc and loss of heterozygosity for the cross-linked Cosmc locus. This is the first example of somatic mutations in multiple types of cancers that cause global alterations in cell surface carbohydrate antigen expression. [Cancer Res 2008;68(6):1636–46]
EphA2 Is an Essential Mediator of UV Radiation–Induced Apoptosis
Authors: Zhang Guoqi , Njauw Ching-Ni , Park Jong Min , Naruse Chie , Asano Masahide , Tsao Hensin
Published: March 2008

One of the physiologic consequences of excessive UV radiation (UVR) exposure is apoptosis. This critical response serves to eliminate genetically injured cells and arises, in part, from activation of DNA damage and p53 signaling. Other contributory pathways, however, likely exist but have not been fully characterized. In a recent global screen of UVR response genes in melanocytes, we identified the receptor tyrosine kinase EPHA2. Using a combination of genetic and pharmacologic approaches, we set out to investigate the upstream regulation of EphA2 by UVR and the functional consequences of this effect. We found that the UVR-associated increase in EphA2 occurs in melanocytes, keratinocytes, and fibroblasts from both human and murine sources. More specifically, UVR effectively up-regulated EphA2 individually in p53-null, p63-null, and p73-null murine embryonic fibroblasts (MEF), suggesting that the p53 family of transcription factors is not essential for the observed effect. However, inhibition of mitogen-activated protein kinase (MAPK) signaling by U0126 and PD98059 significantly reduced the UVR response whereas overexpression of oncogenic NRAS led to an increase in EphA2. These results confirm that UVR induces EphA2 by a p53-independent, but MAPK-dependent, mechanism. In response to UV irradiation, Epha2−/− MEFs were highly resistant to UVR-mediated cytotoxicity and apoptosis whereas introduction of EphA2 into both wild-type and p53-null MEFs led to activation of an apoptotic program that can be blocked by caspase-8 inhibition. These functional findings suggest that EphA2 is in fact an essential p53-independent, caspase-8–dependent proapoptotic factor induced by UVR. [Cancer Res 2008;68(6):1691–6]
Histamine Suppresses Fibulin-5 and Insulin-like Growth Factor-II Receptor Expression in Melanoma
Authors: Pos Zoltan , Wiener Zoltan , Pocza Peter , Racz Melinda , Toth Sara , Darvas Zsuzsanna , Molnar Viktor , Hegyesi Hargita , Falus Andras
Published: March 2008

We previously showed that transgenic enhancement of histamine production in B16-F10 melanomas strongly supports tumor growth in C57BL/6 mice. In the present study, gene expression profiles of transgenic mouse melanomas, secreting different amounts of histamine, were compared by whole genome microarrays. Array results were validated by real-time PCR, and genes showing histamine-affected behavior were further analyzed by immunohistochemistry. Regulation of histamine-coupled genes was investigated by checking the presence and functional integrity of all four known histamine receptors in experimental melanomas and by administering histamine H1 receptor (H1R) and H2 receptor (H2R) antagonists to tumor-bearing mice. Finally, an attempt was made to integrate histamine-affected genes in known gene regulatory circuits by in silico pathway analysis. Our results show that histamine enhances melanoma growth via H1R rather than through H2R. We show that H1R activation suppresses RNA-level expression of the tumor suppressor insulin-like growth factor II receptor (IGF-IIR) and the antiangiogenic matrix protein fibulin-5 (FBLN5), decreases their intracellular protein levels, and also reduces their availability in the plasma membrane and extracellular matrix, respectively. Pathway analysis suggests that because plasma membrane-bound IGF-IIR is required to activate matrix-bound, latent transforming growth factor-β1, a factor suggested to sustain FBLN5 expression, the data can be integrated in a known antineoplastic regulatory pathway that is suppressed by H1R. On the other hand, we show that engagement of H2R also reduces intracellular protein pools of IGF-IIR and FBLN5, but being a downstream acting posttranslational effect with minimal consequences on exported IGF-IIR and FBLN5 protein levels, H2R is rather irrelevant compared with H1R in melanoma. [Cancer Res 2008;68(6):1997–2005]
Capture of Tumor Cell Membranes by Trogocytosis Facilitates Detection and Isolation of Tumor-Specific Functional CTLs
Authors: Machlenkin Arthur , Uzana Ronny , Frankenburg Shoshana , Eisenberg Galit , Eisenbach Lea , Pitcovski Jacob , Gorodetsky Raphael , Nissan Aviram , Peretz Tamar , Lotem Michal
Published: March 2008

The success of adoptive cell transfer in the treatment of metastatic cancer in humans is dependent on the selection of highly active tumor-specific cytotoxic T cells. We report here that CTLs capture membrane fragments from their targets while exerting cytotoxic activity and thus gain a detectable functional signature by which they can be identified. Fluorochrome labeling or biotinylation was used to tag tumor cells. CD8+ T cells were coincubated with the tagged targets, sorted, and functionally evaluated. Our results show that membrane capture by CD8+ lymphocytes is T-cell receptor dependent, epitope specific, and preferentially associated with highly cytotoxic clonal subsets. CTLs that captured membranes from unmodified melanoma exhibited enhanced cytotoxic activity against tumor cell lines and autologous melanoma. In a human melanoma in vivo model, adoptive transfer of membrane-capturing, peptide-specific T cells, but not noncapturing or bulk CD8+ T cells, inhibits tumor progression. Membrane capture is therefore a signature of antigen-specific CTLs endowed with high functional avidity and may have direct relevance in the clinical application of adoptive immunotherapy. [Cancer Res 2008;68(6):2006–13]
Enzastaurin, a Protein Kinase Cβ Inhibitor, Suppresses Signaling through the Ribosomal S6 Kinase and Bad Pathways and Induces Apoptosis in Human Gastric Cancer Cells
Authors: Lee Keun-Wook , Kim Sang Gyun , Kim Hwang-Phill , Kwon Euna , You Jiran , Choi Hyung-Jun , Park Jung-Hyun , Kang Byeong-Cheol , Im Seock-Ah , Kim Tae-You , Kim Woo Ho , Bang Yung-Jue
Published: March 2008

Activation of protein kinase C (PKC) has been implicated in gastric carcinogenesis. Enzastaurin is an oral ATP-competitive inhibitor of the PKCβ isozyme. Although enzastaurin was initially advanced to the clinic based on its antiangiogenic activity, it is also known to have a direct effect on a variety of human cancer cells, inducing apoptosis by inhibiting the Akt signal pathway. However, data on enzastaurin for gastric cancer are limited. Therefore, this study was performed to assess the antitumor activity of enzastaurin on gastric cancer cells and to investigate the underlying antitumor mechanisms. Enzastaurin suppressed the proliferation of cultured gastric cancer cells and the growth of gastric carcinoma xenografts. Enzastaurin did not have an effect on gastric cancer cell cycle progression; however, it had a direct apoptosis-inducing effect through the caspase-mediated mitochondrial pathway. Glycogen synthase kinase 3β phosphorylation, a reliable pharmacodynamic marker of enzastaurin activity, and Akt phosphorylation were both decreased after treatment with enzastaurin. Although the p90 ribosomal S6 kinase (Rsk) was also dephosphorylated, Erk phosphorylation was not affected in the enzastaurin-treated gastric cancer cells. Enzastaurin activated Bad, one of the Bcl-2 proapoptotic proteins, through dephosphorylation at Ser112, and depletion of Bad activity resulted in resistance to enzastaurin-induced apoptosis and cytotoxicity in gastric cancer cells. These data suggest that enzastaurin induces apoptosis through Rsk-mediated and Bad-mediated pathways, besides inhibiting the Akt signal cascade. Furthermore, enzastaurin had synergistic or additive effects when combined with 5-fluorouracil, cisplatin, paclitaxel, or irinotecan. These results warrant further clinical investigation of enzastaurin for gastric cancer treatment. [Cancer Res 2008;68(6):1916–26]
Roles of Achaete-Scute Homologue 1 in DKK1 and E-cadherin Repression and Neuroendocrine Differentiation in Lung Cancer
Authors: Osada Hirotaka , Tomida Shuta , Yatabe Yasushi , Tatematsu Yoshio , Takeuchi Toshiyuki , Murakami Hideki , Kondo Yutaka , Sekido Yoshitaka , Takahashi Takashi
Published: March 2008

The proneural basic-helix-loop-helix protein achaete-scute homologue 1 (ASH1) is expressed in a very limited spectrum of normal and cancerous cells in a lineage-specific manner, including normal pulmonary neuroendocrine cells and lung cancer cells with neuroendocrine features. Our previous results indicated that ASH1 may play a crucial role in the growth and survival of lung cancers with neuroendocrine features, which prompted us to investigate the molecular function of ASH1 in relation to its involvement in carcinogenic processes. Herein, we report for the first time that ASH1 functions as a dual transcription factor by activating neuroendocrine differentiation markers and also repressing putative tumor suppressors. This protein was found to inactivate DKK1 and DKK3, negative regulators of Wnt/β-catenin signaling, E-cadherin, and integrin β1 through ASH1-mediated deacetylation and repressive trimethylation of lysine 27 (H3K27me3) of histone H3 in the promoter regions of DKK1 and E-cadherin. In addition, ASH1-transduced A549 adenocarcinoma cells exhibited markedly altered morphology characteristics compared with lung cancer cells with neuroendocrine features both in vitro and in vivo and also grew faster in vivo. Our results provide important clues for a better understanding of the molecular and cellular biological roles of ASH1 in the process of carcinogenesis of lung cancers with neuroendocrine features and warrant future investigations to shed light on the lineage-specific dependency of this transcription factor with dual functions. [Cancer Res 2008;68(6):1647–55]
The Smo/Smo Model: Hedgehog-Induced Medulloblastoma with 90% Incidence and Leptomeningeal Spread
Authors: Hatton Beryl A. , Villavicencio Elisabeth H. , Tsuchiya Karen D. , Pritchard Joel I. , Ditzler Sally , Pullar Barbara , Hansen Stacey , Knoblaugh Sue E. , Lee Donghoon , Eberhart Charles G. , Hallahan Andrew R. , Olson James M.
Published: March 2008

Toward the goal of generating a mouse medulloblastoma model with increased tumor incidence, we developed a homozygous version of our ND2:SmoA1 model. Medulloblastomas form in 94% of homozygous Smo/Smo mice by 2 months of age. Tumor formation is, thus, predictable by age, before the symptomatic appearance of larger lesions. This high incidence and early onset of tumors is ideal for preclinical studies because mice can be enrolled before symptom onset and with a greater latency period before late-stage disease. Smo/Smo tumors also display leptomeningeal dissemination of neoplastic cells to the brain and spine, which occurs in many human cases. Despite an extended proliferation of granule neuron precursors (GNP) in the postnatal external granular layer (EGL), the internal granular layer formed normally in Smo/Smo mice and tumor formation occurred only in localized foci on the superficial surface of the molecular layer. Thus, tumor formation is not simply the result of over proliferation of GNPs within the EGL. Moreover, Smo/Smo medulloblastomas were transplantable and serially passaged in vivo, demonstrating the aggressiveness of tumor cells and their transformation beyond a hyperplastic state. The Smo/Smo model is the first mouse medulloblastoma model to show leptomeningeal spread. The adherence to human pathology, high incidence, and early onset of tumors thus make Smo/Smo mice an efficient model for preclinical studies. [Cancer Res 2008;68(6):1768–76]
Antitumor Activity and Pharmacology of a Selective Focal Adhesion Kinase Inhibitor, PF-562,271
Authors: Roberts Walter Gregory , Ung Ethan , Whalen Pamela , Cooper Beth , Hulford Catherine , Autry Christofer , Richter Daniel , Emerson Earling , Lin Jing , Kath John , Coleman Kevin , Yao Lili , Martinez-Alsina Luis , Lorenzen Marianne , Berliner Martin , Luzzio Michael , Patel Nandini , Schmitt Erika , LaGreca Susan , Jani Jitesh , Wessel Matt , Marr Eric , Griffor Matt , Vajdos Felix
Published: March 2008

Cancer cells are characterized by the ability to grow in an anchorage-independent manner. The activity of the nonreceptor tyrosine kinase, focal adhesion kinase (FAK), is thought to contribute to this phenotype. FAK localizes in focal adhesion plaques and has a role as a scaffolding and signaling protein for other adhesion molecules. Recent studies show a strong correlation between increased FAK expression and phosphorylation status and the invasive phenotype of aggressive human tumors. PF-562,271 is a potent, ATP-competitive, reversible inhibitor of FAK and Pyk2 catalytic activity with a IC50 of 1.5 and 14 nmol/L, respectively. Additionally, PF-562,271 displayed robust inhibition in an inducible cell-based assay measuring phospho-FAK with an IC50 of 5 nmol/L. PF-562,271 was evaluated against multiple kinases and displays >100× selectivity against a long list of nontarget kinases. PF-562,271 inhibits FAK phosphorylation in vivo in a dose-dependent fashion (calculated EC50 of 93 ng/mL, total) after p.o. administration to tumor-bearing mice. In vivo inhibition of FAK phosphorylation (>50%) was sustained for >4 hours with a single p.o. dose of 33 mg/kg. Antitumor efficacy and regressions were observed in multiple human s.c. xenograft models. No weight loss, morbidity, or mortality were observed in any in vivo experiment. Tumor growth inhibition was dose and drug exposure dependent. Taken together, these data show that kinase inhibition with an ATP-competitive small molecule inhibitor of FAK decreases the phospho-status in vivo, resulting in robust antitumor activity. [Cancer Res 2008;68(6):1935–44]
Oxidative Stress Is Inherent in Prostate Cancer Cells and Is Required for Aggressive Phenotype
Authors: Kumar Binod , Koul Sweaty , Khandrika Lakshmipathi , Meacham Randall B. , Koul Hari K.
Published: March 2008

Reactive oxygen species (ROS) and the coupled oxidative stress have been associated with tumor formation. Several studies suggested that ROS can act as secondary messengers and control various signaling cascades. In the present studies, we characterized the oxidative stress status in three different prostate cancer cells (PC3, DU145, and LNCaP) exhibiting various degree of aggressiveness and normal prostate cells in culture (WPMY1, RWPE1, and primary cultures of normal epithelial cells). We observed increased ROS generation in cancer cells compared with normal cells, and that extramitochondrial source of ROS generator, NAD(P)H oxidase (Nox) systems, are associated with the ROS generation and are critical for the malignant phenotype of prostate cancer cells. Moreover, diphenyliodonium, a specific Nox inhibitor, blocked proliferation, modulated the activity of growth signaling cascades extracellular signal-regulated kinase (ERK)1/ERK2 and p38 mitogen-activated protein kinase as well as AKT protein kinaseB, and caused cyclin B–dependent G2-M cell cycle arrest. We also observed higher degrees of ROS generation in the PC3 cells than DU145 and LNCaP, and that ROS generation is critical for migratory/invasiveness phenotypes. Furthermore, blocking of the ROS production rather than ROS neutralization resulted in decreased matrix metalloproteinase 9 activity as well as loss of mitochondrial potential, plausible reasons for decreased cell invasion and increased cell death. Taken together, these studies show, for the first time, the essential role of ROS production by extramitochondrial source in prostate cancer and suggest that therapies aimed at reducing ROS production might offer effective means of combating prostate cancer in particular, and perhaps other malignancies in general. [Cancer Res 2008;68(6):1777–85]
BAF180 Is a Critical Regulator of p21 Induction and a Tumor Suppressor Mutated in Breast Cancer
Authors: Xia Wei , Nagase Satoru , Montia Amy Gerstein , Kalachikov Sergey M. , Keniry Megan , Su Tao , Memeo Lorenzo , Hibshoosh Hanina , Parsons Ramon
Published: March 2008

Screening for tumor suppressor genes in breast cancer revealed multiple truncating mutations of PB1, which encodes the BAF180 subunit of the PBAF chromatin remodeling complex. Mutation was associated with loss of heterozygosity of the wild-type allele. BAF180 complementation of BAF180-mutant tumor cells caused G1 arrest that was dependent on increased expression of the cyclin/cyclin-dependent kinase inhibitor p21/WAF1/CIP1. Endogenous wild-type BAF180 bound to the p21 promoter and was required for proper p21 expression and G1 arrest after transforming growth factor-β and γ-radiation treatment. BAF180 thus functions on two tumor suppressor signaling pathways as a physiologic mediator of p21 expression. We conclude that BAF180 suppresses tumorigenesis, at least in part, through its ability to regulate p21. [Cancer Res 2008;68(6):1667–74]
Epithelial Progeny of Estrogen-Exposed Breast Progenitor Cells Display a Cancer-like Methylome
Authors: Cheng Alfred S.L. , Culhane Aedín C. , Chan Michael W.Y. , Venkataramu Chinnambally R. , Ehrich Mathias , Nasir Aejaz , Rodriguez Benjamin A.T. , Liu Joseph , Yan Pearlly S. , Quackenbush John , Nephew Kenneth P. , Yeatman Timothy J. , Huang Tim H-M.
Published: March 2008

Estrogen imprinting is used to describe a phenomenon in which early developmental exposure to endocrine disruptors increases breast cancer risk later in adult life. We propose that long-lived, self-regenerating stem and progenitor cells are more susceptible to the exposure injury than terminally differentiated epithelial cells in the breast duct. Mammospheres, containing enriched breast progenitors, were used as an exposure system to simulate this imprinting phenomenon in vitro. Using MeDIP-chip, a methylation microarray screening method, we found that 0.5% (120 loci) of human CpG islands were hypermethylated in epithelial cells derived from estrogen-exposed progenitors compared with the non–estrogen-exposed control cells. This epigenetic event may lead to progressive silencing of tumor suppressor genes, including RUNX3, in these epithelial cells, which also occurred in primary breast tumors. Furthermore, normal tissue in close proximity to the tumor site also displayed RUNX3 hypermethylation, suggesting that this aberrant event occurs in early breast carcinogenesis. The high prevalence of estrogen-induced epigenetic changes in primary tumors and the surrounding histologically normal tissues provides the first empirical link between estrogen injury of breast stem/progenitor cells and carcinogenesis. This finding also offers a mechanistic explanation as to why a tumor suppressor gene, such as RUNX3, can be heritably silenced by epigenetic mechanisms in breast cancer. [Cancer Res 2008;68(6):1786–96]
Deletion of Yin Yang 1 Protein in Osteosarcoma Cells on Cell Invasion and CXCR4/Angiogenesis and Metastasis
Authors: de Nigris Filomena , Rossiello Raffaele , Schiano Concetta , Arra Claudio , Williams-Ignarro Sharon , Barbieri Antonio , Lanza Alessandro , Balestrieri Antonio , Giuliano Maria Teresa , Ignarro Louis J. , Napoli Claudio
Published: March 2008

We know that the Yin Yang 1 protein (YY1) overexpression is positively and strongly correlated with the degree of malignancy of bone tumors. Therefore, we questioned whether we could influence cell invasiveness by deleting YY1 in human osteosarcoma cells (SaOs-2), as tested in Matrigel-coated filters and metastasis implantation of such osteosarcoma cells in vivo, by serial analysis with nuclear magnetic resonance. Moreover, we focused our work on the chemokine receptor CXCR4 and its inhibition by T22 antibody, as well as on systemic (direct in vivo assay) and computer-assisted imaging of angiogenesis-related metastasis. Results showed that cell invasiveness and metastasis implantation by wild-type SaOs-2 cells, as evaluated by histology and immunohistochemistry, are associated with up-regulation of CXCR4 expression, which in turn was significantly reduced by T22. In addition, deletion of YY1 (siRNAYY1-SaOs-2) induced a significant decrease of cell invasion and metastasis growth. This phenomenon was associated with decreased vascular endothelial growth factor (VEGF)/angiogenesis and a complex rearrangement of the gene expression profile as evaluated by microarray analysis. In conclusion, YY1 and VEGF/CXCR4 seem to intervene in the pathogenesis of the malignant phenotype of osteosarcoma by acting on cell invasiveness and metastasis growth. [Cancer Res 2008;68(6):1797–808]
Transforming Growth Factor–β Regulates Mammary Carcinoma Cell Survival and Interaction with the Adjacent Microenvironment
Authors: Bierie Brian , Stover Daniel G. , Abel Ty W. , Chytil Anna , Gorska Agnieszka E. , Aakre Mary , Forrester Elizabeth , Yang Li , Wagner Kay-Uwe , Moses Harold L.
Published: March 2008

Transforming growth factor (TGF)–β signaling has been associated with early tumor suppression and late tumor progression; however, many of the mechanisms that mediate these processes are not known. Using Cre/LoxP technology, with the whey acidic protein promoter driving transgenic expression of Cre recombinase (WAP-Cre), we have now ablated the type II TGF-β receptor (TβRII) expression specifically within mouse mammary alveolar progenitors. Transgenic expression of the polyoma virus middle T antigen, under control of the mouse mammary tumor virus enhancer/promoter, was used to produce mammary tumors in the absence or presence of Cre (TβRII(fl/fl);PY and TβRII(fl/fl);PY;WC, respectively). The loss of TGF-β signaling significantly decreased tumor latency and increased the rate of pulmonary metastasis. The loss of TGF-β signaling was significantly correlated with increased tumor size and enhanced carcinoma cell survival. In addition, we observed significant differences in stromal fibrovascular abundance and composition accompanied by increased recruitment of F4/80+ cell populations in TβRII(fl/fl);PY;WC mice when compared with TβRII(fl/fl);PY controls. The recruitment of F4/80+ cells correlated with increased expression of known inflammatory genes including Cxcl1, Cxcl5, and Ptgs2 (cyclooxygenase-2). Notably, we also identified an enriched K5+ dNp63+ cell population in primary TβRII(fl/fl);PY;WC tumors and corresponding pulmonary metastases, suggesting that loss of TGF-β signaling in this subset of carcinoma cells can contribute to metastasis. Together, our current results indicate that loss of TGF-β signaling in mammary alveolar progenitors may affect tumor initiation, progression, and metastasis through regulation of both intrinsic cell signaling and adjacent stromal-epithelial interactions in vivo. [Cancer Res 2008;68(6):1809–19]
Eag1: An Emerging Oncological Target
Authors: Pardo Luis A. , Stühmer Walter
Published: March 2008

Emerging evidence indicates that ion channels act in a variety of physiologic and pathologic processes beyond electronic signal transmission, including in cancer. We recently found that the potassium channel Eag1 can mediate cancer progression and that a monoclonal antibody, which inhibits Eag1 action, can effectively restrict cancer cell proliferation. We discuss how Eag1 targeting may be useful in diagnostic or therapeutic settings. [Cancer Res 2008;68(6):1611–3]
PC3 Human Prostate Carcinoma Cell Holoclones Contain Self-renewing Tumor-Initiating Cells
Authors: Li Hangwen , Chen Xin , Calhoun-Davis Tammy , Claypool Kent , Tang Dean G.
Published: March 2008

Primary keratinocytes exhibit three typical clonal morphologies represented by holoclones, meroclones, and paraclones, with holoclones containing self-renewing stem cells, and meroclones and paraclones containing more mature and differentiated cells. Interestingly, long-term–cultured human epithelial cancer cells in clonal cultures also form holoclones, meroclones, and paraclones, and tumor cell holoclones have been hypothesized to harbor stem-like cells or cancer stem cells. However, the key question of whether tumor cell holoclones genuinely contain tumor-initiating cells has not been directly addressed. Here, using PC3 human prostate carcinoma cells as a model, we provide direct experimental evidence that tumor cell holoclones contain stem-like cells that can initiate serially transplantable tumors. Importantly, holoclones derived from either cultured PC3 cells or holoclone-initiated tumors can be serially passaged and regenerate all three types of clones. In contrast, meroclones and paraclones cannot be continuously propagated and fail to initiate tumor development. Phenotypic characterizations reveal high levels of CD44, α2β1 integrin, and β-catenin expression in holoclones, whereas meroclones and paraclones show markedly reduced expression of these stem cell markers. The present results have important implications in understanding morphologic heterogeneities and tumorigenic hierarchies in human epithelial cancer cells. [Cancer Res 2008;68(6):1820–5]
Gambogic Acid Inhibits Angiogenesis and Prostate Tumor Growth by Suppressing Vascular Endothelial Growth Factor Receptor 2 Signaling
Authors: Yi Tingfang , Yi Zhengfang , Cho Sung-Gook , Luo Jian , Pandey Manoj K. , Aggarwal Bharat B. , Liu Mingyao
Published: March 2008

Gambogic acid (GA), the main active compound of Gamboge hanburyi, has been previously reported to activate apoptosis in many types of cancer cell lines by targeting transferrin receptor and modulating nuclear factor-κB signaling pathway. Whether GA inhibits angiogenesis, which is crucial for cancer and other human diseases, remains unknown. Here, we found that GA significantly inhibited human umbilical vascular endothelial cell (HUVEC) proliferation, migration, invasion, tube formation, and microvessel growth at nanomolar concentration. In a xenograft prostate tumor model, we found that GA effectively inhibited tumor angiogenesis and suppressed tumor growth with low side effects using metronomic chemotherapy with GA. GA was more effective in activating apoptosis and inhibiting proliferation and migration in HUVECs than in human prostate cancer cells (PC3), suggesting GA might be a potential drug candidate in cancer therapy through angioprevention with low chemotoxicity. Furthermore, we showed that GA inhibited the activations of vascular endothelial growth factor receptor 2 and its downstream protein kinases, such as c-Src, focal adhesion kinase, and AKT. Together, these data suggest that GA inhibits angiogenesis and may be a viable drug candidate in antiangiogenesis and anticancer therapies. [Cancer Res 2008;68(6):1843–50]
Bin3 Deletion Causes Cataracts and Increased Susceptibility to Lymphoma during Aging
Authors: Ramalingam Arivudainambi , Duhadaway James B. , Sutanto-Ward Erika , Wang Yan , Dinchuk Joseph , Huang Minzhou , Donover Preston S. , Boulden Janette , McNally Lois M. , Soler Alejandro P. , Muller Alexander J. , Duncan Melinda K. , Prendergast George C.
Published: March 2008

Bin3 encodes an evolutionarily conserved and ubiquitously expressed member of the BAR superfamily of curved membrane and GTPase-binding proteins, which includes the BAR, PCH/F-BAR, and I-BAR adapter proteins implicated in signal transduction and vesicular trafficking. In humans, Bin3 maps to chromosome 8p21.3, a region widely implicated in cancer suppression that is often deleted in non–Hodgkin's lymphomas and various epithelial tumors. Yeast studies have suggested roles for this gene in filamentous actin (F-actin) organization and cell division but its physiologic functions in mammals have not been investigated. Here we report that homozygous inactivation of Bin3 in the mouse causes cataracts and an increased susceptibility to lymphomas during aging. The cataract phenotype was marked by multiple morphologic defects in lens fibers, including the development of vacuoles in cortical fibers and a near total loss of F-actin in lens fiber cells but not epithelial cells. Through 1 year of age, no other phenotypes were apparent; however, by 18 months of age, Bin3−/− mice exhibited a significantly increased incidence of lymphoma. Bin3 loss did not affect normal cell proliferation, F-actin organization, or susceptibility to oncogenic transformation. In contrast, it increased the proliferation and invasive motility of cells transformed by SV40 large T antigen plus activated ras. Our findings establish functions for Bin3 in lens development and cancer suppression during aging. Further, they define Bin3 as a candidate for an unidentified tumor suppressor that exists at the human chromosome 8p21.3 locus. [Cancer Res 2008;68(6):1683–90]
Targeted Delivery of Gemcitabine to Pancreatic Adenocarcinoma Using Cetuximab as a Targeting Agent
Authors: Patra Chitta Ranjan , Bhattacharya Resham , Wang Enfeng , Katarya Aaron , Lau Julie S. , Dutta Shamit , Muders Michael , Wang Shanfeng , Buhrow Sarah A. , Safgren Stephanie L. , Yaszemski Michael J. , Reid Joel M. , Ames Matthew M. , Mukherjee Priyabrata , Mukhopadhyay Debabrata
Published: March 2008

One of the key challenges in anticancer therapy is the toxicity and poor bioavailability of the anticancer drugs. Nanotechnology can play a pivotal role by delivering drugs in a targeted fashion to the malignant cells that will reduce the systemic toxicity of the anticancer drug. In this report, we show a stepwise development of a nanoparticle-based targeted delivery system for in vitro and in vivo therapeutic application in pancreatic cancer. In the first part of the study, we have shown the fabrication and characterization of the delivery system containing gold nanoparticle as a delivery vehicle, cetuximab as a targeting agent, and gemcitabine as an anticancer drug for in vitro application. Nanoconjugate was first characterized physico-chemically. In vitro targeting efficacy, tested against three pancreatic cancer cell lines (PANC-1, AsPC-1, and MIA Paca2) with variable epidermal growth factor receptor (EGFR) expression, showed that gold uptake correlated with EGFR expression. In the second part, we showed the in vivo therapeutic efficacy of the targeted delivery system. Administration of this targeted delivery system resulted in significant inhibition of pancreatic tumor cell proliferation in vitro and orthotopic pancreatic tumor growth in vivo. Tumor progression was monitored noninvasively by measuring bioluminescence of the implanted tumor cells. Pharmacokinetic experiments along with the quantitation of gold both in vitro and in vivo further confirmed that the inhibition of tumor growth was due to targeted delivery. This strategy could be used as a generalized approach for the treatment of a variety of cancers characterized by overexpression of EGFR. [Cancer Res 2008;68(6):1970–8]
Product Units: A Computationally Powerful and Biologically Plausible Extension to Backpropagation Networks
Authors: Durbin Richard , Rumelhart David E.
Published: March 2008

We introduce a new form of computational unit for feedforward learning networks of the backpropagation type. Instead of calculating a weighted sum this unit calculates a weighted product, where each input is raised to a power determined by a variable weight. Such a unit can learn an arbitrary polynomial term, which would then feed into higher level standard summing units. We show how learning operates with product units, provide examples to show their efficiency for various types of problems, and argue that they naturally extend the family of theoretical feedforward net structures. There is a plausible neurobiological interpretation for one interesting configuration of product and summing units.
Deterministic Boltzmann Learning Performs Steepest Descent in Weight-Space
Authors: Hinton Geoffrey E.
Published: March 2008

The Boltzmann machine learning procedure has been successfully applied in deterministic networks of analog units that use a mean field approximation to efficiently simulate a truly stochastic system (Peterson and Anderson 1987). This type of “deterministic Boltzmann machine” (DBM) learns much faster than the equivalent “stochastic Boltzmann machine” (SBM), but since the learning procedure for DBM's is only based on an analogy with SBM's, there is no existing proof that it performs gradient descent in any function, and it has only been justified by simulations. By using the appropriate interpretation for the way in which a DBM represents the probability of an output vector given an input vector, it is shown that the DBM performs steepest descent in the same function as the original SBM, except at rare discontinuities. A very simple way of forcing the weights to become symmetrical is also described, and this makes the DBM more biologically plausible than back-propagation (Werbos 1974; Parker 1985; Rumelhart et al. 1986).
Criteria for Robust Stability In A Class Of Lateral Inhibition Networks Coupled Through Resistive Grids
Authors: Wyatt John L. , Standley David L.
Published: March 2008

In the analog VLSI implementation of neural systems, it is sometimes convenient to build lateral inhibition networks by using a locally connected on-chip resistive grid to interconnect active elements. A serious problem of unwanted spontaneous oscillation often arises with these circuits and renders them unusable in practice. This paper reports on criteria that guarantee these and certain other systems will be stable, even though the values of designed elements in the resistive grid may be imprecise and the location and values of parasitic elements may be unknown. The method is based on a rigorous, somewhat novel mathematical analysis using Tellegen's theorem (Penfield et al. 1970) from electrical circuits and the idea of a Popov multiplier (Vidyasagar 1978; Desoer and Vidya sagar 1975) from control theory. The criteria are local in that no overall analysis of the interconnected system is required for their use, empirical in that they involve only measurable frequency response data on the individual cells, and robust in that they are insensitive to network topology and to unmodelled parasitic resistances and capacitances in the interconnect network. Certain results are robust in the additional sense that specified nonlinear elements in the grid do not affect the stability criteria. The results are designed to be applicable, with further development, to complex and incompletely modeled living neural systems.
Two Stages of Curve Detection Suggest Two Styles of Visual Computation
Authors: Zucker Steven W. , Dobbins Allan , Iverson Lee
Published: March 2008

The problem of detecting curves in visual images arises in both computer vision and biological visual systems. Our approach integrates constraints from these two sources and suggests that there are two different stages to curve detection, the first resulting in a local description, and the second in a global one. Each stage involves a different style of computation: in the first stage, hypotheses are represented explicitly and coarsely in a fixed, preconfigured architecture; in the second stage, hypotheses are represented implicitly and more finely in a dynamically constructed architecture. We also show how these stages could be related to physiology, specifying the earlier parts in a relatively fine-grained fashion and the later ones more coarsely.
Computing Optical Flow in the Primate Visual System
Authors: Wang H. Taichi , Mathur Bimal , Koch Christof
Published: March 2008

Computing motion on the basis of the time-varying image intensity is a difficult problem for both artificial and biological vision systems. We show how gradient models, a well-known class of motion algorithms, can be implemented within the magnocellular pathway of the primate's visual system. Our cooperative algorithm computes optical flow in two steps. In the first stage, assumed to be located in primary visual cortex, local motion is measured while spatial integration occurs in the second stage, assumed to be located in the middle temporal area (MT). The final optical flow is extracted in this second stage using population coding, such that the velocity is represented by the vector sum of neurons coding for motion in different directions. Our theory, relating the single-cell to the perceptual level, accounts for a number of psychophysical and electrophysiological observations and illusions.
A Neural Model for Generation of Some Behaviors in the Fictive Scratch Reflex
Authors: Shadmehr Reza
Published: March 2008

We have studied the scratch reflex in order to better understand the strategy that the spinal neural structures use to program limb movements. A network is proposed for the positioning and rhythmic portions of the scratch reflex in the deafferented preparation. This model is based on Berkinblit's hypotheses regarding organization of neurons constituting the spinal central pattern generator (CPG) for this behavior. We offer a mechanism by which the initial position of the hindlimb can influence the output of the CPG in the immobilized animal.
Learning State Space Trajectories in Recurrent Neural Networks
Authors: Pearlmutter Barak A.
Published: March 2008

Many neural network learning procedures compute gradients of the errors on the output layer of units after they have settled to their final values. We describe a procedure for finding ∂E/∂wij, where E is an error functional of the temporal trajectory of the states of a continuous recurrent network and wij are the weights of that network. Computing these quantities allows one to perform gradient descent in the weights to minimize E. Simulations in which networks are taught to move through limit cycles are shown. This type of recurrent network seems particularly suited for temporally continuous domains, such as signal processing, control, and speech.
Surface Interpolation in Three-Dimensional Structure-from-Motion Perception
Authors: Husain Masud , Treue Stefan , Andersen Richard A.
Published: March 2008

Although it is appreciated that humans can use a number of visual cues to perceive the three-dimensional (3-D) shape of an object, for example, luminance, orientation, binocular disparity, and motion, the exact mechanisms employed are not known (De Yoe and Van Essen 1988). An important approach to understanding the computations performed by the visual system is to develop algorithms (Marr 1982) or neural network models (Lehky and Sejnowski 1988; Siegel 1987) that are capable of computing shape from specific cues in the visual image. In this study we investigated the ability of observers to see the 3-D shape of an object using motion cues, so called structure-from-motion (SFM). We measured human performance in a two-alternative forced choice task using novel dynamic random-dot stimuli with limited point lifetimes. We show that the human visual system integrates motion information spatially and temporally (across several point lifetimes) as part of the process for computing SFM. We conclude that SFM algorithms must include surface interpolation to account for human performance. Our experiments also provide evidence that local velocity information, and not position information derived from discrete views of the image (as proposed by some algorithms), is used to solve the SFM problem by the human visual system.