bluuebunny/crossref_metadata_2025 huggingface dataset:
Management of Lipids in the Prevention of Cardiovascular Events
Authors: Glassberg Helene , Rader Daniel J.
Published: October 2007

Lipid-modifying therapy has been proven to significantly reduce cardiovascular events and total mortality. Most of the data have come from statin trials. Statin therapy is generally well-tolerated and safe, and for patients who are at higher than average risk of cardiovascular disease, the benefit of lipid-modifying therapy far exceeds the risk. Careful risk assessment is a critical component of effective lipid-modifying therapy. In the foreseeable future, low-density lipoprotein cholesterol (LDL-C) will remain the primary therapeutic target, and combination therapy is likely to become the norm. The major questions are how low to treat and how to achieve increasingly aggressive targets in lipid-lowering therapy. Many patients on LDL-lowering therapy continue to have abnormalities of the triglyceride–high-density lipoprotein (TG-HDL) axis, so additional drug therapy is often considered for such patients. In this review, we briefly discuss new developments in cardiovascular risk assessment, then discuss recent developments in treatment to reduce LDL, and finally discuss current concepts regarding therapy targeting the TG-HDL axis.
Strategic Approach to Fit-for-Purpose Biomarkers in Drug Development
Authors: Wagner John A.
Published: October 2007

The strategic, fit-for-purpose use of the combination of robust target engagement and well-qualified disease-related biomarkers enhances understanding of the mechanism of action, ties together preclinical and clinical data, enables the assessment of target engagement, facilitates early proof of concept and dose focusing, and increases the efficiency of early clinical development with improved quality of decision making. Significant progress in biomarker discovery, validation, and qualification has increased drug-development decision making and regulatory applications. Target engagement biomarkers are present early in a pathophysiologic cascade and inform on physical or biological interactions with the molecular target of the drug. Disease-related biomarkers are present late in the pathophysiologic cascade and are linked to clinical benefit; thus, they assess a drug's effect on a particular disease. Together, these concepts lay the groundwork for high-quality drug-development decision making and a framework for the acceptance and qualification of biomarkers for regulatory use.
Regulation of GPCRs by Endocytic Membrane Trafficking and Its Potential Implications
Authors: Hanyaloglu Aylin C. , Zastrow Mark von
Published: October 2007

The endocytic pathway tightly controls the activity of G protein–coupled receptors (GPCRs). Ligand-induced endocytosis can drive receptors into divergent lysosomal and recycling pathways, producing essentially opposite effects on the strength and duration of cellular signaling via heterotrimeric G proteins, and may also promote distinct signaling events from intracellular membranes. This chapter reviews recent developments toward understanding the molecular machinery and functional implications of GPCR sorting in the endocytic pathway, focusing on mammalian GPCRs whose ligand-induced endocytosis is mediated primarily by clathrin-coated pits. Lysosomal sorting of a number of GPCRs occurs via a highly conserved mechanism requiring covalent tagging of receptors with ubiquitin. There is increasing evidence that additional, noncovalent mechanisms control the sorting of endocytosed GPCRs to lysosomes in mammalian cells. Recycling of several GPCRs to the plasma membrane is also specifically sorted, via a mechanism requiring both receptor-specific and shared sorting proteins. The current data reveal an unprecedented degree of specificity and plasticity in the cellular regulation of mammalian GPCRs by endocytic membrane trafficking. These developments have fundamental implications for GPCR pharmacology, and suggest new mechanisms that could be exploited in GPCR-directed pharmacotherapy.
Targeting Chemokine Receptors in HIV: A Status Report
Authors: Kuhmann Shawn E. , Hartley Oliver
Published: October 2007

Since the identification of CCR5 and CXCR4 as HIV coreceptors a little over a decade ago, there has been hope that coreceptor inhibitors will be able to make an impact on the HIV epidemic, both as novel therapeutic drugs and as agents used in prevention. Significant progress has been made in the understanding of how coreceptor choice might impact HIV pathology and how coreceptor blockade may affect health. In this review, we focus on some of the key issues that are emerging now that CCR5 has been validated as a promising target for HIV prevention strategies and at a time when a CCR5 inhibitor has been approved in the United States as the first in a new class of anti-HIV therapeutic drugs.
Structures, Kinetics, Thermodynamics, and Biological Functions of RNA Hairpins
Authors: Bevilacqua Philip C. , Blose Joshua M.
Published: October 2007

Most RNA comprises one strand and therefore can fold back on itself to form complex structures. At the heart of these structures is the hairpin, which is composed of a stem having Watson-Crick base pairing and a loop wherein the backbone changes directionality. First, we review the structure of hairpins including diversity in the stem, loop, and closing base pair. The function of RNA hairpins in biology is discussed next, including roles for isolated hairpins, as well as hairpins in the context of complex tertiary structures. We describe the kinetics and thermodynamics of hairpin folding including models for hairpin folding, folding transition states, and the cooperativity of folding. Lastly, we discuss some ways in which hairpins can influence the folding and function of tertiary structures, both directly and indirectly. RNA hairpins provide a simple means of controlling gene expression that can be understood in the language of physical chemistry.
Health Psychology: The Search for Pathways between Behavior and Health
Authors: Leventhal Howard , Weinman John , Leventhal Elaine A. , Phillips L. Alison
Published: October 2007

This review of the current status of theoretically based behavioral research for chronic illness management makes the following points: (a) Behavioral interventions have demonstrated effectiveness for improving health outcomes using biomedical indicators, (b) current interventions are too costly and time consuming to be used in clinical and community settings, (c) translation of the conceptual models generated from studies of the problem-solving processes underlying self-management and the relationship of these processes to the self system and cultural and institutional contexts suggest new avenues for developing effective and efficient cognitive-behavioral interventions, and (d) it is proposed that integration of the conceptual developments in self-management with new approaches to the design of clinical trials can generate tailored, behavioral interventions that will improve quality of care.
Increased lipid accumulation and insulin resistance in transgenic mice expressing DGAT2 in glycolytic (type II) muscle
Authors: Levin Malin C. , Monetti Mara , Watt Matthew J. , Sajan Mini P. , Stevens Robert D. , Bain James R. , Newgard Christopher B. , Farese Robert V. , Farese Robert V.
Published: October 2007

Insulin resistance and type 2 diabetes are frequently accompanied by lipid accumulation in skeletal muscle. However, it is unknown whether primary lipid deposition in skeletal muscle is sufficient to cause insulin resistance or whether the type of muscle fiber, oxidative or glycolytic fiber, is an important determinant of lipid-mediated insulin resistance. Here we utilized transgenic mice to test the hypothesis that lipid accumulation specifically in glycolytic muscle promotes insulin resistance. Overexpression of DGAT2, which encodes an acyl-CoA:diacylglycerol acyltransferase that catalyzes triacylglycerol (TG) synthesis, in glycolytic muscle of mice increased the content of TG, ceramides, and unsaturated long-chain fatty acyl-CoAs in young adult mice. This lipid accumulation was accompanied by impaired insulin signaling and insulin-mediated glucose uptake in glycolytic muscle and impaired whole body glucose and insulin tolerance. We conclude that DGAT2-mediated lipid deposition specifically in glycolytic muscle promotes insulin resistance in this tissue and may contribute to the development of diabetes.
Reduced nitric oxide in diabetic kidneys due to increased hepatic arginine metabolism: implications for renomedullary oxygen availability
Authors: Palm Fredrik , Friederich Malou , Carlsson Per-Ola , Hansell Peter , Teerlink Tom , Liss Per
Published: October 2007

Nitric oxide (NO) is a potent regulator of both vascular tone and oxygen utilization. Diabetes is commonly associated with both NO deficiency and reduced renomedullary oxygen availability. Arginine availability as regulator of NO production has gained growing interest. We hypothesized that arginine limitation causes diabetes-induced renomedullary NO deficiency, which directly influences renomedullary oxygen tension (Po2). Medullary NO, Po2, and blood flow were measured in control and streptozotocin-induced diabetic rats, which were treated or not treated with α-tocopherol, and administered l-arginine followed by Nω-nitro-l-arginine methyl ester. Major components of arginine metabolism were also investigated. Diabetic rats had reduced renomedullary NO levels compared with controls. Arginine selectively increased NO levels in diabetic rats and totally restored NO levels in α-tocopherol-treated animals. Tocopherol prevented the reduction in medullary Po2 in the diabetic animals. Although blood flow increased equally in all groups, arginine increased Po2 exclusively in the diabetic groups. Diabetes decreased plasma arginine and asymmetric dimethylarginine concentrations, but increased hepatic CAT-2A and plasma ornithine independently of α-tocopherol treatment. In conclusion, diabetic rats had reduced renomedullary NO due to decreased plasma arginine following increased hepatic arginine uptake and degradation. This was unrelated to oxidative stress. The diabetes-induced reduction in renomedullary Po2 was restored by either acute arginine administration, which also restored NO levels, or long-term antioxidant treatment. Arginine increased medullary NO and Po2 independently of altered hemodynamics in the diabetic groups. This reveals a direct regulatory function of NO for renomedullary Po2 especially during situations of elevated oxidative stress.
Encoding of Action History in the Rat Ventral Striatum
Authors: Kim Yun Bok , Huh Namjung , Lee Hyunjung , Baeg Eun Ha , Lee Daeyeol , Jung Min Whan
Published: October 2007

In a dynamic environment, animals need to update information about the rewards expected from their alternative actions continually to make optimal choices for its survival. Because the reward resulting from a given action can be substantially delayed, the process of linking a reward to its causative action would be facilitated by memory signals related to the animal's previous actions. Although the ventral striatum has been proposed to play a key role in updating the information about the rewards expected from specific actions, it is not known whether the signals related to previous actions exist in the ventral striatum. In the present study, we recorded neuronal ensemble activity in the rat ventral striatum during a visual discrimination task and investigated whether neuronal activity in the ventral striatum encoded signals related to animal's previous actions. The results show that many neurons modulated their activity according to the animal's goal choice in the previous trial, indicating that memory signals for previous actions are available in the ventral striatum. In contrast, few neurons conveyed signals on impending goal choice of the animal, suggesting the absence of decision signals in the ventral striatum. Memory signals for previous actions might contribute to the process of updating the estimates of rewards expected from alternative actions in the ventral striatum.
Divergent evolution of the myosin heavy chain gene family in fish and tetrapods: evidence from comparative genomic analysis
Authors: Ikeda Daisuke , Ono Yosuke , Snell Phil , Edwards Yvonne J. K. , Elgar Greg , Watabe Shugo
Published: October 2007

Myosin heavy chain genes ( MYHs) are the most important functional domains of myosins, which are highly conserved throughout evolution. The human genome contains 15 MYHs, whereas the corresponding number in teleost appears to be much higher. Although teleosts comprise more than one-half of all vertebrate species, our knowledge of MYHs in teleosts is rather limited. A comprehensive analysis of the torafugu ( Takifugu rubripes) genome database enabled us to detect at least 28 MYHs, almost twice as many as in humans. RT-PCR revealed that at least 16 torafugu MYH representatives (5 fast skeletal, 3 cardiac, 2 slow skeletal, 1 superfast, 2 smooth, and 3 nonmuscle types) are actually transcribed. Among these, MYHM743-2and MYHM5of fast and slow skeletal types, respectively, are expressed during development of torafugu embryos. Syntenic analysis reveals that torafugu fast skeletal MYHs are distributed across five genomic regions, three of which form clusters. Interestingly, while human fast skeletal MYHs form one cluster, its syntenic region in torafugu is duplicated, although each locus contains just a single MYH in torafugu. The results of the syntenic analysis were further confirmed by corresponding analysis of MYHs based on databases from Tetraodon, zebrafish, and medaka genomes. Phylogenetic analysis suggests that fast skeletal MYHs evolved independently in teleosts and tetrapods after fast skeletal MYHs had diverged from four ancestral MYHs.
Adoptively Transferred Tumor-Specific T Cells StimulatedEx vivoUsing Herpes Simplex Virus Amplicons Encoding 4-1BBL Persist in the Host and Show Antitumor ActivityIn vivo
Authors: Yi Kyung H. , Nechushtan Hovav , Bowers William J. , Walker Gail R. , Zhang Yu , Pham Dien G. , Podack Eckhard R. , Federoff Howard J. , Tolba Khaled A. , Rosenblatt Joseph D.
Published: October 2007

4-1BB is a T-cell costimulatory receptor which binds its ligand 4-1BBL, resulting in prolonged T cell survival. We studied the antitumor effects of adoptively transferred tumor-specific T cells expanded ex vivo using tumors transduced with herpes simplex virus (HSV) amplicons expressing 4-1BBL as a direct source of antigen and costimulation. We constructed HSV amplicons encoding either the 4-1BBL (HSV.4-1BBL) or B7.1 (HSV.B7.1) costimulatory ligands. Lewis lung carcinoma cells expressing ovalbumin (LLC/OVA) were transduced with HSV.4-1BBL, HSV.B7.1, or control HSV amplicons and used to stimulate GFP+ OVA-specific CD8+ T cells (OT-1/GFP) ex vivo. Naive or ex vivo stimulated OT-1/GFP cells were adoptively transferred into LLC/OVA tumor-bearing mice. Higher percentages of OT-1/GFP cells were seen in the peripheral blood, spleen, and tumor bed of the HSV.4-1BBL–stimulated OT-1/GFP group compared with all other experimental groups. OT-1 cells identified within the tumor bed and draining lymph nodes of the HSV.4-1BBL–stimulated OT-1 group showed enhanced bromodeoxyuridine (BrdUrd) incorporation, suggesting ongoing expansion in vivo. Mice receiving HSV.4-1BBL–stimulated OT-1/GFP had significantly decreased tumor volumes compared with untreated mice (P < 0.001) or to mice receiving naive OT-1/GFP (P < 0.001). Transfer of HSV.B7.1-stimulated OT-1/GFP did not protect mice from tumor. Mice that received HSV.4-1BBL–stimulated OT-1/GFP exhibited increased cytolytic activity against LLC/OVA and higher percentages of Ly-6C+ OT-1/GFP in the spleen and tumor bed compared with controls. Tumor-specific T cells stimulated ex vivo using tumor transduced with HSV.4-1BBL expand in vivo following adoptive transfer, resulting in tumor eradication and the generation of tumor-specific CD44+Ly-6C+CD62L− effector memory T cells. [Cancer Res 2007;67(20):10027–37]
A Cathepsin K Inhibitor Reduces Breast Cancer–Induced Osteolysis and Skeletal Tumor Burden
Authors: Le Gall Céline , Bellahcène Akeila , Bonnelye Edith , Gasser Jürg A. , Castronovo Vincent , Green Jonathan , Zimmermann Johann , Clézardin Philippe
Published: October 2007

Osteoclasts mediate bone destruction in breast cancer skeletal metastases. Cathepsin K is a proteinase that is secreted by osteoclasts and degrades bone. Here, immunohistochemistry revealed that cathepsin K was expressed not only by osteoclasts but also by breast cancer cells that metastasize to bone. Following intratibial injection with cathepsin K–expressing human BT474 breast cancer cells, tumor-bearing mice treated with a clinical dosing regimen of cathepsin K inhibitor (CKI; 50 mg/kg, twice daily) had osteolytic lesions that were 79% smaller than those of tumor-bearing mice treated with the vehicle. The effect of CKI was also studied in a mouse model in which the i.v. inoculation of human B02 breast cancer cells expressing cathepsin K leads to bone metastasis formation. Drug administration was started before (preventive protocol) or after (treatment protocol) the occurrence of osteolytic lesions. In treatment protocols, CKI (50 mg/kg, twice daily) or a single clinical dose of 100 μg/kg zoledronic acid (osteoclast inhibitor) reduced the progression of osteolytic lesions by 59% to 66%. CKI therapy also reduced skeletal tumor burden by 62% compared with vehicle, whereas zoledronic acid did not decrease the tumor burden. The efficacy of CKI at inhibiting skeletal tumor burden was similar in the treatment and preventive protocols. By contrast, CKI did not block the growth of s.c. B02 tumor xenografts in animals. Thus, CKI may render the bone a less favorable microenvironment for tumor growth by inhibiting bone resorption. These findings raise the possibility that cathepsin K could be a therapeutic target for the treatment of bone metastases. [Cancer Res 2007;67(20):9894–902]
Gene Amplification and Overexpression of PRDM14 in Breast Cancers
Authors: Nishikawa Noriko , Toyota Minoru , Suzuki Hiromu , Honma Toshio , Fujikane Tomoko , Ohmura Tousei , Nishidate Toshihiko , Ohe-Toyota Mutsumi , Maruyama Reo , Sonoda Tomoko , Sasaki Yasushi , Urano Takeshi , Imai Kohzoh , Hirata Koichi , Tokino Takashi
Published: October 2007

Several genes that encode PR (PRDI-BF1 and RIZ) domain proteins (PRDM) have been linked to human cancers. To explore the role of the PR domain family genes in breast carcinogenesis, we examined the expression profiles of 16 members of the PRDM gene family in a panel of breast cancer cell lines and primary breast cancer specimens using semiquantitative real-time PCR. We found that PRDM14 mRNA is overexpressed in about two thirds of breast cancers; moreover, immunohistochemical analysis showed that expression of PRDM14 protein is also up-regulated. Analysis of the gene copy number revealed that PRDM14 is a target of gene amplification on chromosome 8q13, which is a region where gene amplification has frequently been detected in various human tumors. Introduction of PRDM14 into cancer cells enhanced cell growth and reduced their sensitivity to chemotherapeutic drugs. Conversely, knockdown of PRDM14 by siRNA induced apoptosis in breast cancer cells and increased their sensitivity to chemotherapeutic drugs, suggesting that up-regulated expression of PRDM14 may play an important role in the proliferation of breast cancer cells. That little or no expression of PRDM14 is seen in noncancerous tissues suggests that PRDM14 could be an ideal therapeutic target for the treatment of breast cancer. [Cancer Res 2007;67(20):9649–57]
Thymic Stromal-Derived Lymphopoietin Induces Proliferation of Pre-B Leukemia and Antagonizes mTOR Inhibitors, Suggesting a Role for Interleukin-7Rα Signaling
Authors: Brown Valerie I. , Hulitt Jessica , Fish Jonathan , Sheen Cecilia , Bruno Marlo , Xu Qing , Carroll Martin , Fang Junjie , Teachey David , Grupp Stephan A.
Published: October 2007

Understanding the pathogenesis of leukemia in the context of lymphopoiesis may reveal novel therapeutic targets. Previously, we have shown that mTOR inhibitors (MTI) show activity in vitro and in preclinical models of both human and murine precursor B acute lymphoblastic leukemia (pre-B ALL), inhibiting cell proliferation and inducing apoptosis. These MTI-mediated effects can be reversed by interleukin-7 (IL-7), an important regulator of early B-cell development. This observation led us to examine the contribution of signaling via the IL-7Rα chain, which is shared by the receptor complexes of IL-7 and thymic stromal-derived lymphopoietin (TSLP). TSLP is closely related to IL-7 and active in lymphopoiesis, but an effect of TSLP on leukemia cells has not been described. We examined the effect of TSLP on pre-B ALL cells and their response to MTIs. Here, we show that TSLP stimulates proliferation of pre-B ALL cell lines. TSLP also partially reverses the effects of MTI on proliferation, apoptosis, and ribosomal protein S6 and 4E-BP1 phosphorylation in cell lines, with similar biological effects seen in some primary human lymphoblast samples. These data show that TSLP can promote survival of pre-B ALL cells and antagonize the effects of MTIs. These findings suggest that IL-7Rα chain is responsible for transducing the survival signal that overcomes MTI-mediated growth inhibition in pre-B ALL. Thus, further exploration of the IL-7Rα pathway may identify potential therapeutic targets in the treatment of ALL. Our data illustrate that growth-factor–mediated signaling may provide one mechanism of MTI resistance. [Cancer Res 2007;67(20):9963–70]
Opposing Roles of Murine Duffy Antigen Receptor for Chemokine and Murine CXC Chemokine Receptor-2 Receptors in Murine Melanoma Tumor Growth
Authors: Horton Linda W. , Yu Yingchun , Zaja-Milatovic Snjezana , Strieter Robert M. , Richmond Ann
Published: October 2007

The Duffy antigen receptor for chemokines (DARC) has been classified as a “silent” receptor, as it can bind CXC and CC chemokines to undergo ligand-induced receptor internalization, but is not coupled to trimeric G proteins required for the classic G protein–coupled receptor–mediated signaling. CXC chemokine receptor-2 (CXCR2) has been shown to play a major role in tumor angiogenesis. To test the hypothesis that these two chemokine receptors might play opposing roles in the growth of melanoma tumors, we developed a transgenic mouse model, where the preproendothelin promoter/enhancer (PPEP) is used to drive expression of either murine DARC (mDARC) or murine CXCR2 (mCXCR2) in endothelial cells. We show herein that the growth of melanoma tumor xenografts, established from s.c. injection of immortalized murine melanocytes overexpressing macrophage inflammatory protein-2, was inhibited or enhanced in the PPEP-mDARC and PPEP-mCXCR2 transgenic mice, respectively, compared with control mice. The early tumors formed in mDARC transgenic mice exhibited a significantly higher number of infiltrating leukocytes compared with either the control or mCXCR2 transgenic mice, suggesting a potential role for DARC expressed on endothelial cells in leukocyte migration. In addition, the tumor-associated angiogenesis in mDARC transgenic mice was reduced when compared with the control. Conversely, tumor angiogenesis was significantly increased in mCXCR2 transgenic mice. Results indicate that endothelial cell overexpression of mDARC increased leukocyte trafficking to the tumor, reduced the growth of blood vessels into the tumor, and reduced the growth rate of the tumor, whereas endothelial cell overexpression of mCXCR2 had the reverse effect on tumor angiogenesis and growth. [Cancer Res 2007;67(20):9791–9]
CUL7 Is a Novel Antiapoptotic Oncogene
Authors: Kim Sam S. , Shago Mary , Kaustov Lilia , Boutros Paul C. , Clendening James W. , Sheng Yi , Trentin Grace A. , Barsyte-Lovejoy Dalia , Mao Daniel Y.L. , Kay Robert , Jurisica Igor , Arrowsmith Cheryl H. , Penn Linda Z.
Published: October 2007

Using an expression cloning approach, we identify CUL7, a member of the cullin family, as a functional inhibitor of Myc-induced apoptosis. Deregulated expression of the Myc oncogene drives cellular proliferation yet also sensitizes cells to undergo p53-dependent and p53-independent apoptosis. Here, we report that CUL7 exerts its antiapoptotic function through p53. CUL7 binds directly to p53, and small interfering RNA–mediated knockdown of CUL7 results in the elevation of p53 protein levels. This antiapoptotic role of CUL7 enables this novel oncogene to cooperate with Myc to drive transformation. Deregulated ectopic expression of c-Myc and CUL7 promotes Rat1a cell growth in soft agar, and knockdown of CUL7 significantly blocks human neuroblastoma SHEP cell growth in an anchorage-independent manner. Furthermore, using public microarray data sets, we show that CUL7 mRNA is significantly overexpressed in non–small cell lung carcinoma and is associated with poor patient prognosis. We provide experimental evidence to show CUL7 is a new oncogene that cooperates with Myc in transformation by blocking Myc-induced apoptosis in a p53-dependent manner. [Cancer Res 2007;67(20):9616–22]
Batracylin (NSC 320846), a Dual Inhibitor of DNA Topoisomerases I and II Induces Histone γ-H2AX as a Biomarker of DNA Damage
Authors: Rao V. Ashutosh , Agama Keli , Holbeck Susan , Pommier Yves
Published: October 2007

Batracylin (8-aminoisoindolo [1,2-b]quinazolin-10(12H)-one; NSC320846) is an investigational clinical anticancer agent. Previous animal studies showed activity against solid tumors and Adriamycin-resistant leukemia. We initially sought to test the proposed Top2-mediated DNA cleavage activity of batracylin and identify potential biomarkers for activity. COMPARE analysis in the NCI-60 cell lines showed batracylin activity to be most closely related to the class of Top2 inhibitors. The 50% growth inhibition (GI50) value for batracylin in HT29 colon carcinoma cells was 10 μmol/L. DNA-protein cross-links, consistent with Top2 targeting, were measured by alkaline elution. DNA single-strand breaks were also detected and found to be protein associated. However, only a weak induction of DNA double-strand breaks was observed. Because batracylin induced almost exclusively DNA single-strand breaks, we tested batracylin as a Top1 inhibitor. Batracylin exhibited both Top1- and Top2α/β-mediated DNA cleavage in vitro and in cells. The phosphorylation of histone (γ-H2AX) was tested to measure the extent of DNA damage. Kinetics of γ-H2AX “foci” showed early activation with low μmol/L concentrations, thus presenting a useful early biomarker of DNA damage. The half-life of γ-H2AX signal reversal after drug removal was consistent with reversal of DNA-protein cross-links. The persistence of the DNA-protein complexes induced by batracylin was markedly longer than by etoposide or camptothecin. The phosphorylated DNA damage–responsive kinase, ataxia telangiectasia mutated, was also found activated at sites of γ-H2AX. The cell cycle checkpoint kinase, Chk2, was only weakly phosphorylated. Thus, batracylin is a dual Top1 and Top2 inhibitor and γ-H2AX could be considered a biomarker in the ongoing clinical trials. [Cancer Res 2007;67(20):9971–9]
A Human CD4 Monoclonal Antibody for the Treatment of T-Cell Lymphoma Combines Inhibition of T-Cell Signaling by a Dual Mechanism with Potent Fc-Dependent Effector Activity
Authors: Rider David A. , Havenith Carin E.G. , de Ridder Ruby , Schuurman Janine , Favre Cedric , Cooper Joanne C. , Walker Simon , Baadsgaard Ole , Marschner Susanne , vandeWinkel Jan G.J. , Cambier John , Parren Paul W.H.I. , Alexander Denis R.
Published: October 2007

Zanolimumab is a human IgG1 antibody against CD4, which is in clinical development for the treatment of cutaneous and nodal T-cell lymphomas. Here, we report on its mechanisms of action. Zanolimumab was found to inhibit CD4+ T cells by combining signaling inhibition with the induction of Fc-dependent effector mechanisms. First, T-cell receptor (TCR) signal transduction is inhibited by zanolimumab through a fast, dual mechanism, which is activated within minutes. Ligation of CD4 by zanolimumab effectively inhibits early TCR signaling events but, interestingly, activates signaling through the CD4-associated tyrosine kinase p56lck. An uncoupling of p56lck from the TCR by anti-CD4 allows the kinase to transmit direct inhibitory signals via the inhibitory adaptor molecules Dok-1 and SHIP-1. Second, CD4+ T cells are killed by induction of antibody-dependent cell-mediated cytotoxicity, to which CD45RO+ cells are more sensitive than CD45RA+ cells. Finally, zanolimumab induces down-modulation of CD4 from cell surfaces via a slow Fc-dependent mechanism. In conclusion, zanolimumab rapidly inhibits T-cell signaling via a dual mechanism of action combined with potent Fc-dependent lysis of CD4+ T cells and may act long-term by down-regulating CD4. [Cancer Res 2007;67(20):9945–53]
A Novel Small Molecule Inhibitor of Signal Transducers and Activators of Transcription 3 Reverses Immune Tolerance in Malignant Glioma Patients
Authors: Hussain S. Farzana , Kong Ling-Yuan , Jordan Justin , Conrad Charles , Madden Timothy , Fokt Isabella , Priebe Waldemar , Heimberger Amy B.
Published: October 2007

Overcoming the profound immunosuppression in patients with solid cancers has impeded efficacious immunotherapy. Signal transducers and activators of transcription 3 (STAT3) has recently emerged as a potential target for effective immunotherapy, and in this study, we describe a novel small molecule inhibitor of STAT3 that can penetrate the central nervous system (CNS) in mice and in physiologically relevant doses in vitro and reverse tolerance in immune cells isolated from glioblastoma multiforme (GBM) patients. Specifically, it induces the expression of costimulatory molecules on peripheral macrophages and tumor-infiltrating microglia, stimulates the production of the immune-stimulatory cytokines interleukin 2 (IL-2), IL-4, IL-12, and IL-15, and induces proliferation of effector T cells from GBM patients that are refractory to CD3 stimulation. We show that the functional enhancement of immune responses after STAT3 inhibition is accompanied by up-regulation of several key intracellular signaling molecules that critically regulate T-cell and monocyte activation. Specifically, the phosphorylation of Syk (Tyr352) in monocytes and ZAP-70 (Tyr319) in T cells are enhanced by the STAT-3 inhibitor in marked contrast to toll-like receptor and T-cell receptor agonists, respectively. This novel small molecule STAT3 inhibitor has tremendous potential for clinical applications with its penetration into the CNS, easy parental administration, direct tumor cytotoxicity, and potent immune adjuvant responses in immunosuppressed cancer patients. [Cancer Res 2007;67(20):9630–6]
In vivo Functional Analysis of the Counterbalance of Hyperactive Phosphatidylinositol 3-Kinase p110 Catalytic Oncoproteins by the Tumor Suppressor PTEN
Authors: Andrés-Pons Amparo , Rodríguez-Escudero Isabel , Gil Anabel , Blanco Ana , Vega Ana , Molina María , Pulido Rafael , Cid Víctor J.
Published: October 2007

The signaling pathways involving class I phosphatidylinositol 3-kinases (PI3K) and the phosphatidylinositol-(3,4,5)-trisphosphate phosphatase PTEN regulate cell proliferation and survival. Thus, mutations in the corresponding genes are associated to a wide variety of human tumors. Heterologous expression of hyperactive forms of mammalian p110α and p110β in Saccharomyces cerevisiae leads to growth arrest, which is counterbalanced by coexpression of mammalian PTEN. Using this in vivo yeast-based system, we have done an extensive functional analysis of germ-line and somatic human PTEN mutations, as well as a directed mutational analysis of discrete PTEN functional domains. A distinctive penetrance of the PTEN rescue phenotype was observed depending on the levels of PTEN expression in yeast and on the combinations of the inactivating PTEN mutations and the activating p110α or p110β mutations analyzed, which may reflect pathologic differences found in tumors with distinct alterations at the p110 and PTEN genes or proteins. We also define the minimum length of the PTEN protein required for stability and function in vivo. In addition, a random mutagenesis screen on PTEN based on this system allowed both the reisolation of known clinically relevant PTEN mutants and the identification of novel PTEN loss-of-function mutations, which were validated in mammalian cells. Our results show that the PI3K/PTEN yeast-based system is a sensitive tool to test in vivo the pathologic properties and the functionality of mutations in the human p110 proto-oncogenes and the PTEN tumor suppressor and provide a framework for comprehensive functional studies of these tumor-related enzymes. [Cancer Res 2007;67(20):9731–9]
Suppression of Epidermal Growth Factor Receptor Signaling by Protein Kinase C-α Activation Requires CD82, Caveolin-1, and Ganglioside
Authors: Wang Xiao-qi , Yan Qiu , Sun Ping , Liu Ji-Wei , Go Linda , McDaniel Shauntae M. , Paller Amy S.
Published: October 2007

Activation of protein kinase C (PKC)-α decreases normal and neoplastic cell proliferation by inhibiting epidermal growth factor receptor (EGFR)-related signaling. The molecular interactions upstream to PKC-α that influence its suppression of EGFR, however, are poorly understood. We have found that caveolin-1, tetraspanin CD82, and ganglioside GM3 enable the association of EGFR with PKC-α, ultimately leading to inhibition of EGFR signaling. GM3- and CD82-induced inhibition of EGFR signaling requires PKC-α translocation and serine/threonine phosphorylation, which eventually triggers EGFR Thr654 phosphorylation and receptor internalization. Within this ordered complex of signaling molecules, the ability of CD82 to associate with PKC-α requires the presence of caveolin-1, whereas the interaction of caveolin-1 or PKC-α with EGFR requires the presence of CD82 and ganglioside GM3. Disruption of the membrane with methyl-β-cyclodextrin dissociates the EGFR/GM3/caveolin-1/CD82/PKC-α complex and prevents the inhibitory effect of PKC-α on EGFR phosphorylation, suggesting that caveolin-1, CD82, and ganglioside interact with EGFR and PKC-α within intact cholesterol-enriched membrane microdomains. Given the role of these membrane molecules in suppressing EGFR signaling, up-regulation of GM3, caveolin-1, and CD82 function may be an effective adjunctive therapy for treating epithelial cell malignancies. [Cancer Res 2007;67(20):9986–95]
MAGE-A, mMage-b, and MAGE-C Proteins Form Complexes with KAP1 and Suppress p53-Dependent Apoptosis in MAGE-Positive Cell Lines
Authors: Yang Bing , O'Herrin Sean M. , Wu Jianqiang , Reagan-Shaw Shannon , Ma Yongsheng , Bhat Kumar M.R. , Gravekamp Claudia , Setaluri Vijayasaradhi , Peters Noel , Hoffmann F. Michael , Peng Hongzhuang , Ivanov Alexey V. , Simpson Andrew J.G. , Longley B. Jack
Published: October 2007

The MAGE-A, MAGE-B, and MAGE-C protein families comprise the class-I MAGE/cancer testes antigens, a group of highly homologous proteins whose expression is suppressed in all normal tissues except developing sperm. Aberrant expression of class I MAGE proteins occurs in melanomas and many other malignancies, and MAGE proteins have long been recognized as tumor-specific targets; however, their functions have largely been unknown. Here, we show that suppression of class I MAGE proteins induces apoptosis in the Hs-294T, A375, and S91 MAGE-positive melanoma cell lines and that members of all three families of MAGE class I proteins form complexes with KAP1, a scaffolding protein that is known as a corepressor of p53 expression and function. In addition to inducing apoptosis, MAGE suppression decreases KAP1 complexing with p53, increases immunoreactive and acetylated p53, and activates a p53 responsive reporter gene. Suppression of class I MAGE proteins also induces apoptosis in MAGE-A–positive, p53wt/wt parental HCT 116 colon cancer cells but not in a MAGE-A–positive HCT 116 p53−/− variant, indicating that MAGE suppression of apoptosis requires p53. Finally, treatment with MAGE-specific small interfering RNA suppresses S91 melanoma growth in vivo, in syngenic DBA2 mice. Thus, class I MAGE protein expression may suppress apoptosis by suppressing p53 and may actively contribute to the development of malignancies and by promoting tumor survival. Because the expression of class I MAGE proteins is limited in normal tissues, inhibition of MAGE antigen expression or function represents a novel and specific treatment for melanoma and diverse malignancies. [Cancer Res 2007;67(20):9954–62]
Nek2 as an Effective Target for Inhibition of Tumorigenic Growth and Peritoneal Dissemination of Cholangiocarcinoma
Authors: Kokuryo Toshio , Senga Takeshi , Yokoyama Yukihiro , Nagino Masato , Nimura Yuji , Hamaguchi Michinari
Published: October 2007

We investigated the role of Nek2, a member of the serine/threonine kinase family, Nek, in the tumorigenic growth of cholangiocarcinoma cells. Expression of Nek2 is elevated in cholangiocarcinoma in a tumor-specific manner as compared with that of normal fibroblast cells. Expression of exogenous Nek2 did not perturb the growth of cholangiocarcinoma cells, whereas suppression of the Nek2 expression with siRNA resulted in the inhibition of cell proliferation and induced cell death. In xenograft-nude mouse model, s.c. injection of Nek2 siRNA around the tumor nodules resulted in reduction of tumor size as compared with those of control siRNA injection. In peritoneal dissemination model, Nek2 siRNA–treated mice showed statistically longer survival periods in comparison with those of the control siRNA–treated mice. Taken together, our data indicate a pivotal role of Nek2 in tumorigenic growth of cholangiocarcinoma. [Cancer Res 2007;67(20):9637–42]
Bcl-2 Orchestrates a Cross-talk between Endothelial and Tumor Cells that Promotes Tumor Growth
Authors: Kaneko Tomoatsu , Zhang Zhaocheng , Mantellini Maria G. , Karl Elisabeta , Zeitlin Benjamin , Verhaegen Monique , Soengas María S. , Lingen Mark , Strieter Robert M. , Nunez Gabriel , Nör Jacques E.
Published: October 2007

The current understanding of the interaction between the endothelium and cancer cells is fundamentally based on the concept that endothelial cells are responsive to differentiation and survival signals originating from the tumor cells. Whereas the effect of tumor cell–secreted factors on angiogenesis is well established, little is known about the effect of factors secreted by endothelial cells on tumor cell gene expression and tumor progression. Here, we show that bcl-2 gene expression is significantly higher in the tumor-associated endothelial cells of patients with head and neck squamous cell carcinomas (HNSCC) as compared with endothelial cells from the normal oral mucosa. Bcl-2 induces vascular endothelial growth factor (VEGF) expression in neovascular endothelial cells through a signal transducer and activator of transcription 3 (STAT3)–mediated pathway. Endothelial cell–derived VEGF signals through VEGFR1 and induces expression of Bcl-2 and the proangiogenic chemokines CXCL1 and CXCL8 in HNSCC cells. Notably, inhibition of Bcl-2 expression in neovascular endothelial cells with RNA interference down-regulates expression of Bcl-2, CXCL8, and CXCL1 in HNSCC cells, and is sufficient to inhibit growth and decrease the microvessel density of xenografted HNSCC in immunodeficient mice. Together, these results show that Bcl-2 is the orchestrator of a cross-talk between neovascular endothelial cells and tumor cells, which has a direct effect on tumor growth. This work identifies a new function for Bcl-2 in cancer biology that is beyond its classic role in cell survival. [Cancer Res 2007;67(20):9685–93]
Transforming Growth Factor-β Promotes Survival of Mammary Carcinoma Cells through Induction of Antiapoptotic Transcription Factor DEC1
Authors: Ehata Shogo , Hanyu Aki , Hayashi Makoto , Aburatani Hiroyuki , Kato Yukio , Fujime Makoto , Saitoh Masao , Miyazawa Keiji , Imamura Takeshi , Miyazono Kohei
Published: October 2007

Transforming growth factor-β (TGF-β) signaling facilitates tumor growth and metastasis in advanced cancer. In the present study, we identified differentially expressed in chondrocytes 1 (DEC1, also known as SHARP2 and Stra13) as a downstream target of TGF-β signaling, which promotes the survival of breast cancer cells. In the mouse mammary carcinoma cell lines JygMC(A) and 4T1, the TGF-β type I receptor kinase inhibitors A-44-03 and SB431542 induced apoptosis of cells under serum-free conditions. Oligonucleotide microarray and real-time reverse transcription-PCR analyses revealed that TGF-β induced DEC1 in these cells, and the increase of DEC1 was suppressed by the TGF-β type I receptor kinase inhibitors as well as by expression of dominant-negative TGF-β type II receptor. Overexpression of DEC1 prevented the apoptosis of JygMC(A) cells induced by A-44-03, and knockdown of endogenous DEC1 abrogated TGF-β–promoted cell survival. Moreover, a dominant-negative mutant of DEC1 prevented lung and liver metastasis of JygMC(A) cells in vivo. Our observations thus provide new insights into the molecular mechanisms governing TGF-β–mediated cell survival and metastasis of cancer. [Cancer Res 2007;67(20):9694–703]
Targeting Cancer with Bugs and Liposomes: Ready, Aim, Fire
Authors: Cheong Ian , Huang Xin , Thornton Katherine , Diaz Luis A. , Zhou Shibin
Published: October 2007

One of the major challenges facing cancer therapy today is achieving specificity. Current efforts to meet this challenge are focused on developing targeted therapeutics specific to the cancer cell. An alternative approach is to selectively deliver cytotoxic agents to the tumor site. With this end in mind, liposomes optimized for physical robustness have been developed and used clinically as drug delivery vehicles. Paradoxically, the effectiveness of these liposomes is hampered by the suboptimal release of bioavailable drug. This article will highlight the recent advance in using a novel lipase secreted by the tumor-colonizing anaerobic bacterium Clostridium novyi-NT to induce the targeted release of liposomal payloads within tumors. [Cancer Res 2007;67(20):9605–8]
Helper Function of Memory CD8+ T Cells: Heterologous CD8+ T Cells Support the Induction of Therapeutic Cancer Immunity
Authors: Nakamura Yutaro , Watchmaker Payal , Urban Julie , Sheridan Brian , Giermasz Adam , Nishimura Fumihiko , Sasaki Kotaro , Cumberland Rachel , Muthuswamy Ravikumar , Mailliard Robbie B. , Larregina Adriana T. , Falo Louis D. , Gooding William , Storkus Walter J. , Okada Hideho , Hendricks Robert L. , Kalinski Pawel
Published: October 2007

In contrast to the well-established efficacy of preventive vaccines, the effectiveness of therapeutic vaccines remains limited. To develop effective vaccination regimens against cancer, we have analyzed the effect of effector and memory CD8+ T cells on the ability of dendritic cells to mediate the immunologic and antitumor effects of vaccination. We show that in contrast to effector CD8+ T cells that kill antigen-carrying dendritic cells, IFNγ-producing memory CD8+ T cells act as “helper” cells, supporting the ability of dendritic cells to produce interleukin-12 (IL-12) p70. Promoting the interaction of tumor antigen-carrying dendritic cells with memory-type “heterologous” (tumor-irrelevant) CD8+ T cells strongly enhances the IL-12p70-dependent immunogenic and therapeutic effects of vaccination in the animals bearing established tumors. Our data show that the suppressive and helper functions of CD8+ T cells are differentially expressed at different phases of CD8+ T-cell responses. Selective performance of helper functions by memory (in contrast to effector) CD8+ T cells helps to explain the phenomenon of immune memory and facilitates the design of effective therapeutic vaccines against cancer and chronic infections. [Cancer Res 2007;67(20):10012–8
Loss of Hepatocyte Growth Factor/c-Met Signaling Pathway Accelerates Early Stages of N-nitrosodiethylamine–Induced Hepatocarcinogenesis
Authors: Takami Taro , Kaposi-Novak Pal , Uchida Koichi , Gomez-Quiroz Luis E. , Conner Elizabeth A. , Factor Valentina M. , Thorgeirsson Snorri S.
Published: October 2007

Hepatocyte growth factor (HGF) has been reported to have both positive and negative effects on carcinogenesis. Here, we show that the loss of c-Met signaling in hepatocytes enhanced rather than suppressed the early stages of chemical hepatocarcinogenesis. c-Met conditional knockout mice (c-metfl/fl, AlbCre+/−; MetLivKO) treated with N-nitrosodiethylamine developed significantly more and bigger tumors and with a shorter latency compared with control (w/w, AlbCre+/−; Cre-Ctrl) mice. Accelerated tumor development was associated with increased rate of cell proliferation and prolonged activation of epidermal growth factor receptor (EGFR) signaling. MetLivKO livers treated with N-nitrosodiethylamine also displayed elevated lipid peroxidation, decreased ratio of reduced glutathione to oxidized glutathione, and up-regulation of superoxide dismutase 1 and heat shock protein 70, all consistent with increased oxidative stress. Likewise, gene expression profiling done at 3 and 5 months after N-nitrosodiethylamine treatment revealed up-regulation of genes associated with cell proliferation and stress responses in c-Met mutant livers. The negative effects of c-Met deficiency were reversed by chronic p.o. administration of antioxidant N–acetyl–l-cysteine. N–acetyl–l-cysteine blocked the EGFR activation and reduced the N-nitrosodiethylamine–initiated hepatocarcinogenesis to the levels of Cre-Ctrl mice. These results argue that intact HGF/c-Met signaling is essential for maintaining normal redox homeostasis in the liver and has tumor suppressor effect(s) during the early stages of N-nitrosodiethylamine–induced hepatocarcinogenesis. [Cancer Res 2007;67(20):9844–51]
Inhibition of MEK Sensitizes Human Melanoma Cells to Endoplasmic Reticulum Stress-Induced Apoptosis
Authors: Jiang Chen Chen , Chen Li Hua , Gillespie Susan , Wang Yu Fang , Kiejda Kelly A. , Zhang Xu Dong , Hersey Peter
Published: October 2007

Past studies have shown that activation of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK is a common cause for resistance of melanoma cells to death receptor–mediated or mitochondria-mediated apoptosis. We report in this study that inhibition of the MEK/ERK pathway also sensitizes melanoma cells to endoplasmic reticulum (ER) stress-induced apoptosis, and this is mediated, at least in part, by caspase-4 activation and is associated with inhibition of the ER chaperon glucose-regulated protein 78 (GRP78) expression. Treatment with the ER stress inducer tunicamycin or thapsigargin did not induce significant apoptosis in the majority of melanoma cell lines, but resistance to these agents was reversed by the MEK inhibitor U0126 or MEK1 small interfering RNA (siRNA). Induction of apoptosis by ER stress when MEK was inhibited was caspase dependent with caspase-4, caspase-9, and caspase-3 being involved. Caspase-4 seemed to be the apical caspase in that caspase-4 activation occurred before activation of caspase-9 and caspase-3 and that inhibition of caspase-4 by a specific inhibitor or siRNA blocked activation of caspase-9 and caspase-3, whereas inhibition of caspase-9 or caspase-3 did not inhibit caspase-4 activation. Moreover, overexpression of Bcl-2 inhibited activation of caspase-9 and caspase-3 but had minimal effect on caspase-4 activation. Inhibition of MEK/ERK also resulted in down-regulation of GRP78, which was physically associated with caspase-4, before and after treatment with tunicamycin or thapsigargin. In addition, siRNA knockdown of GRP78 increased ER stress-induced caspase-4 activation and apoptosis. Taken together, these results seem to have important implications for new treatment strategies in melanoma by combinations of agents that induce ER stress and inhibitors of the MEK/ERK pathway. [Cancer Res 2007;67(20):9750–61]