bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Prenatal Protein Malnutrition on Long-Term Potentiation and BDNF Protein Expression in the Rat Entorhinal Cortex after Neocortical and Hippocampal Tetanization
Authors: Hernández Alejandro , Burgos Héctor , Mondaca Mauricio , Barra Rafael , Núñez Héctor , Pérez Hernán , Soto-Moyano Rubén , Sierralta Walter , Fernández Victor , Olivares Ricardo , Valladares Luis
Published: July 2008

Reduction of the protein content from 25 to 8% casein in the diet of pregnant rats results in impaired neocortical long-term potentiation (LTP) of the offspring together with lower visuospatial memory performance. The present study was aimed to investigate whether this type of maternal malnutrition could result in modification of plastic capabilities of the entorhinal cortex (EC) in the adult progeny. Unlike normal eutrophic controls, 55–60-day-old prenatally malnourished rats were unable to develop LTP in the medial EC to tetanizing stimulation delivered to either the ipsilateral occipital cortex or the CA1 hippocampal region. Tetanizing stimulation of CA1 also failed to increase the concentration of brain-derived neurotrophic factor (BDNF) in the EC of malnourished rats. Impaired capacity of the EC of prenatally malnourished rats to develop LTP and to increase BDNF levels during adulthood may be an important factor contributing to deficits in learning performance having adult prenatally malnourished animals.
Automated Quantitative Assessment of Proteins′ Biological Function in Protein Knowledge Bases
Authors: Mayr Gabriele , Lepperdinger Günter , Lackner Peter
Published: July 2008

Primary protein sequence data are archived in databases together with information regarding corresponding biological functions. In this respect, UniProt/Swiss‐Prot is currently the most comprehensive collection and it is routinely cross‐examined when trying to unravel the biological role of hypothetical proteins. Bioscientists frequently extract single entries and further evaluate those on a subjective basis. In lieu of a standardized procedure for scoring the existing knowledge regarding individual proteins, we here report about a computer‐assisted method, which we applied to score the present knowledge about any given Swiss‐Prot entry. Applying this quantitative score allows the comparison of proteins with respect to their sequence yet highlights the comprehension of functional data. pfs analysis may be also applied for quality control of individual entries or for database management in order to rank entry listings.
C-Myc Is a Critical Mediator of the Phenotypes of Apc Loss in the Intestine
Authors: Wilkins Julie A. , Sansom Owen J.
Published: July 2008

The Adenomatous polyposis coli (Apc) gene is mutated in up to 80% of sporadic colorectal cancers. After Apc loss, there is deregulation of the Wnt signaling pathway and transactivation of T-cell factor/leukemia enhancing factor target genes such as C-Myc. This review focuses on recent data highlighting the importance of the C-Myc oncogene and its transcriptional targets in establishing all of the phenotypes caused by the deletion of the Apc tumor suppressor gene within the intestinal epithelium. The importance of investigating Apc and C-Myc gene function in the correct tissue context is also discussed. [Cancer Res 2008;68(13):4963–6]
Loss of the ssecks/gravin/akap12 Gene Results in Prostatic Hyperplasia
Authors: Akakura Shin , Huang Changhui , Nelson Peter J. , Foster Barbara , Gelman Irwin H.
Published: July 2008

SSeCKS/Gravin/AKAP12 (SSeCKS) is a kinase scaffolding protein that encodes metastasis-suppressor activity through the suppression of Src-mediated oncogenic signaling and vascular endothelial growth factor expression. SSeCKS expression is down-regulated in Src- and Ras-transformed fibroblasts, in human cancer cell lines and in several types of human cancer, including prostate. Normal human and mouse prostates express abundant SSeCKS in secretory epithelial cells and, to a lesser extent, in the surrounding mesenchyme. Here, we show that the loss of SSeCKS results in prostatic hyperplasia in the anterior and ventral lobes as well as increased levels of apoptosis throughout the prostate. Dysplastic foci were observed less frequently but were associated with the loss of E-cadherin staining and the loss of high molecular weight cytokeratin-positive basal epithelial cells. SSeCKS-null prostate tissues expressed significantly higher relative levels of AKTpoS473 compared with wild-type controls, suggesting that SSeCKS attenuates phosphatidylinositol-3-OH kinase signaling. The data suggest that SSeCKS-null mice have increased susceptibility for oncogenic transformation in the prostate. [Cancer Res 2008;68(13):5096–103]
Cross-talk between Notch and the Estrogen Receptor in Breast Cancer Suggests Novel Therapeutic Approaches
Authors: Rizzo Paola , Miao Haixi , D'Souza Gwendolyn , Osipo Clodia , Yun Jieun , Zhao Huiping , Mascarenhas Joaquina , Wyatt Debra , Antico Giovanni , Hao Lu , Yao Katharine , Rajan Prabha , Hicks Chindo , Siziopikou Kalliopi , Selvaggi Suzanne , Bashir Amina , Bhandari Deepali , Marchese Adriano , Lendahl Urban , Qin Jian-Zhong , Tonetti Debra A. , Albain Kathy , Nickoloff Brian J. , Miele Lucio
Published: July 2008

High expression of Notch-1 and Jagged-1 mRNA correlates with poor prognosis in breast cancer. Elucidating the cross-talk between Notch and other major breast cancer pathways is necessary to determine which patients may benefit from Notch inhibitors, which agents should be combined with them, and which biomarkers indicate Notch activity in vivo. We explored expression of Notch receptors and ligands in clinical specimens, as well as activity, regulation, and effectors of Notch signaling using cell lines and xenografts. Ductal and lobular carcinomas commonly expressed Notch-1, Notch-4, and Jagged-1 at variable levels. However, in breast cancer cell lines, Notch-induced transcriptional activity did not correlate with Notch receptor levels and was highest in estrogen receptor α–negative (ERα−), Her2/Neu nonoverexpressing cells. In ERα+ cells, estradiol inhibited Notch activity and Notch-1IC nuclear levels and affected Notch-1 cellular distribution. Tamoxifen and raloxifene blocked this effect, reactivating Notch. Notch-1 induced Notch-4. Notch-4 expression in clinical specimens correlated with proliferation (Ki67). In MDA-MB231 (ERα−) cells, Notch-1 knockdown or γ-secretase inhibition decreased cyclins A and B1, causing G2 arrest, p53-independent induction of NOXA, and death. In T47D:A18 (ERα+) cells, the same targets were affected, and Notch inhibition potentiated the effects of tamoxifen. In vivo, γ-secretase inhibitor treatment arrested the growth of MDA-MB231 tumors and, in combination with tamoxifen, caused regression of T47D:A18 tumors. Our data indicate that combinations of antiestrogens and Notch inhibitors may be effective in ERα+ breast cancers and that Notch signaling is a potential therapeutic target in ERα− breast cancers. [Cancer Res 2008;68(13):5226–35]
Dissecting and Targeting the Growth Factor–Dependent and Growth Factor–Independent Extracellular Signal-Regulated Kinase Pathway in Human Schwannoma
Authors: Ammoun Sylwia , Flaiz Christine , Ristic Natalia , Schuldt Jennifer , Hanemann C. Oliver
Published: July 2008

Schwannomas are tumors of the nervous system that occur sporadically and in patients with the cancer predisposition syndrome neurofibromatosis type 2 (NF2). Schwannomas and all NF2-related tumors are caused by loss of the tumor suppressor merlin. Using our human in vitro model for schwannoma, we analyzed extracellular signal-regulated kinase 1/2 (ERK1/2) and AKT signaling pathways, their upstream growth factor receptors, and their role in schwannoma cell proliferation and adhesion to find new systemic therapies for these tumors that, to date, are very difficult to treat. We show here that human primary schwannoma cells show an enhanced basal Raf/mitogen-activated protein/ERK kinase/ERK1/2 pathway activity compared with healthy Schwann cells. Due to a strong and prolonged activation of platelet-derived growth factor receptor β (PDGFRβ), which is highly overexpressed, ERK1/2 and AKT activation was further increased in schwannoma, leading to increased proliferation. Using specific inhibitors, we discovered that ERK1/2 activation involves the integrin/focal adhesion kinase/Src/Ras signaling cascades and PDGFRβ-mediated ERK1/2 activation is triggered through the phosphatidylinositol 3-kinase/protein kinase C/Src/c-Raf pathway. Due to the complexity of signals leading to schwannoma cell proliferation, potential new therapeutic agents should target several signaling pathways. The PDGFR and c-Raf inhibitor sorafenib (BAY 43-9006; Bayer Pharmaceuticals), currently approved for treatment of advanced renal cell cancer, inhibits both basal and PDGFRβ-mediated ERK1/2 and AKT activity and decreases cell proliferation in human schwannoma cells, suggesting that this drug constitutes a promising tool to treat schwannomas. We conclude that our schwannoma in vitro model can be used to screen for new therapeutic targets in general and that sorafenib is possible candidate for future clinical trials. [Cancer Res 2008;68(13):5236–45]
Noninvasive Imaging and Quantification of Epidermal Growth Factor Receptor Kinase Activation In vivo
Authors: Li Wenrong , Li Fang , Huang Qian , Frederick Barbara , Bao Shideng , Li Chuan-Yuan
Published: July 2008

Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase (RTK) critical in tumor growth and a major target for anticancer drug development. However, thus far, there is no effective system to monitor its activities in vivo. Here, we report a novel approach to monitor EGFR activation based on the bifragment luciferase reconstitution system. The EGFR receptor and its interacting partner proteins (EGFR, growth factor receptor binding protein 2, and Src homology 2 domain-containing) were fused to NH2 terminal and COOH terminal fragments of the firefly luciferase. After establishing tumor xenograft from cells transduced with the reporter genes, we show that the activation of EGFR and its downstream factors could be quantified through optical imaging of reconstituted luciferase. Changes in EGFR activation could be visualized after radiotherapy or EGFR inhibitor treatment. Rapid and sustained radiation-induced EGFR activation and inhibitor-mediated signal suppression were observed in the same xenograft tumors over a period of weeks. Our data therefore suggest a new methodology where activities of RTKs can be imaged and quantified optically in mice. This approach should be generally applicable to study biological regulation of RTK, as well as to develop and evaluate novel RTK-targeted therapeutics. [Cancer Res 2008;68(13):4990–7]
Mitochondrial Cholesterol Contributes to Chemotherapy Resistance in Hepatocellular Carcinoma
Authors: Montero Joan , Morales Albert , Llacuna Laura , Lluis Josep M. , Terrones Oihana , Basañez Gorka , Antonsson Bruno , Prieto Jesús , García-Ruiz Carmen , Colell Anna , Fernández-Checa José C.
Published: July 2008

Cholesterol metabolism is deregulated in carcinogenesis, and cancer cells exhibit enhanced mitochondrial cholesterol content whose role in cell death susceptibility and cancer therapy has not been investigated. Here, we describe that mitochondria from rat or human hepatocellular carcinoma (HC) cells (HCC) or primary tumors from patients with HC exhibit increased mitochondrial cholesterol levels. HCC sensitivity to chemotherapy acting via mitochondria is enhanced upon cholesterol depletion by inhibition of hydroxymethylglutaryl-CoA reductase or squalene synthase (SS), which catalyzes the first committed step in cholesterol biosynthesis. HCC transfection with siRNA targeting the steroidogenic acute regulatory protein StAR, a mitochondrial cholesterol–transporting polypeptide which is overexpressed in HCC compared with rat and human liver, sensitized HCC to chemotherapy. Isolated mitochondria from HCC with increased cholesterol levels were resistant to mitochondrial membrane permeabilization and release of cytochrome c or Smac/DIABLO in response to various stimuli including active Bax. Similar behavior was observed in cholesterol-enriched mitochondria or liposomes and reversed by restoring mitochondrial membrane order or cholesterol extraction. Moreover, atorvastatin or the SS inhibitor YM-53601 potentiated doxorubicin-mediated HCC growth arrest and cell death in vivo. Thus, mitochondrial cholesterol contributes to chemotherapy resistance by increasing membrane order, emerging as a novel therapeutic niche in cancer therapy. [Cancer Res 2008;68(13):5246–56]
A Syngeneic Variance Library for Functional Annotation of Human Variation: Application toBRCA2
Authors: Hucl Tomas , Rago Carlo , Gallmeier Eike , Brody Jonathan R. , Gorospe Myriam , Kern Scott E.
Published: July 2008

The enormous scope of natural human genetic variation is now becoming defined. To accurately annotate these variants, and to identify those with clinical importance, is often difficult to assess through functional assays. We explored systematic annotation by using homologous recombination to modify a native gene in hemizygous (wt/Δexon) human cancer cells, generating a novel syngeneic variance library (SyVaL). We created a SyVaL of BRCA2 variants: nondeleterious, proposed deleterious, deleterious, and of uncertain significance. We found that the null states BRCA2Δex11/Δex11 and BRCA2Δex11/Y3308X were deleterious as assessed by a loss of RAD51 focus formation on genotoxic damage and by acquisition of toxic hypersensitivity to mitomycin C and etoposide, whereas BRCA2Δex11/Y3308Y, BRCA2Δex11/P3292L, and BRCA2Δex11/P3280H had wild-type function. A proposed phosphorylation site at codon 3291 affecting function was confirmed by substitution of an acidic residue (glutamate, BRCA2Δex11/S3291E) for the native serine, but in contrast to a prior report, phosphorylation was dispensable (alanine, BRCA2Δex11/S3291A) for BRCA2-governed cellular phenotypes. These results show that SyVaLs offer a means to comprehensively annotate gene function, facilitating numerical and unambiguous readouts. SyVaLs may be especially useful for genes in which functional assays using exogenous expression are toxic or otherwise unreliable. They also offer a stable, distributable cellular resource for further research. [Cancer Res 2008;68(13):5023–30]
OX40 Agonist Therapy Enhances CD8 Infiltration and Decreases Immune Suppression in the Tumor
Authors: Gough Michael J. , Ruby Carl E. , Redmond William L. , Dhungel Birat , Brown Alexis , Weinberg Andrew D.
Published: July 2008

Acquisition of full T-cell effector function and memory differentiation requires appropriate costimulatory signals, including ligation of the costimulatory molecule OX40 (TNFRSF4, CD134). Tumors often grow despite the presence of tumor-specific T cells and establish an environment with weak costimulation and immune suppression. Administration of OX40 agonists has been shown to significantly increase the survival of tumor-bearing mice and was dependent on the presence of both CD4 and CD8 T cells during tumor-specific priming. To understand how OX40 agonists work in mice with established tumors, we developed a model to study changes in immune cell populations within the tumor environment. We show here that systemic administration of OX40 agonist antibodies increased the proportion of CD8 T cells at the tumor site in three different tumor models. The function of the CD8 T cells at the tumor site was also increased by administration of OX40 agonist antibody, and we observed an increase in the proportion of antigen-specific CD8 T cells within the tumor. Despite decreases in the proportion of T regulatory cells at the tumor site, T regulatory cell function in the spleen was unaffected by OX40 agonist antibody therapy. Interestingly, administration of OX40 agonist antibody caused significant changes in the tumor stroma, including decreased macrophages, myeloid-derived suppressor cells, and decreased expression of transforming growth factor-β. Thus, therapies targeting OX40 dramatically changed the tumor environment by enhancing the infiltration and function of CD8 T cells combined with diminished suppressive influences within the tumor. [Cancer Res 2008;68(13):5206–15]
A Gene Signature Predicting for Survival in Suboptimally Debulked Patients with Ovarian Cancer
Authors: Bonome Tomas , Levine Douglas A. , Shih Joanna , Randonovich Mike , Pise-Masison Cindy A. , Bogomolniy Faina , Ozbun Laurent , Brady John , Barrett J. Carl , Boyd Jeff , Birrer Michael J.
Published: July 2008

Despite the existence of morphologically indistinguishable disease, patients with advanced ovarian tumors display a broad range of survival end points. We hypothesize that gene expression profiling can identify a prognostic signature accounting for these distinct clinical outcomes. To resolve survival-associated loci, gene expression profiling was completed for an extensive set of 185 (90 optimal/95 suboptimal) primary ovarian tumors using the Affymetrix human U133A microarray. Cox regression analysis identified probe sets associated with survival in optimally and suboptimally debulked tumor sets at a P value of <0.01. Leave-one-out cross-validation was applied to each tumor cohort and confirmed by a permutation test. External validation was conducted by applying the gene signature to a publicly available array database of expression profiles of advanced stage suboptimally debulked tumors. The prognostic signature successfully classified the tumors according to survival for suboptimally (P = 0.0179) but not optimally debulked (P = 0.144) patients. The suboptimal gene signature was validated using the independent set of tumors (odds ratio, 8.75; P = 0.0146). To elucidate signaling events amenable to therapeutic intervention in suboptimally debulked patients, pathway analysis was completed for the top 57 survival-associated probe sets. For suboptimally debulked patients, confirmation of the predictive gene signature supports the existence of a clinically relevant predictor, as well as the possibility of novel therapeutic opportunities. Ultimately, the prognostic classifier defined for suboptimally debulked tumors may aid in the classification and enhancement of patient outcome for this high-risk population. [Cancer Res 2008;68(13):5478–86]
Molecular Dependence of Estrogen Receptor–Negative Breast Cancer on a Notch-Survivin Signaling Axis
Authors: Lee Connie W. , Raskett Christopher M. , Prudovsky Igor , Altieri Dario C.
Published: July 2008

Despite progress in the management of breast cancer, the molecular underpinnings of clinically aggressive subtypes of the disease are not well-understood. Here, we show that activation of Notch developmental signaling in estrogen receptor (ER)–negative breast cancer cells results in direct transcriptional up-regulation of the apoptosis inhibitor and cell cycle regulator survivin. This response is associated with increased expression of survivin at mitosis, enhanced cell proliferation, and heightened viability at cell division. Conversely, targeting Notch signaling with a peptidyl γ-secretase inhibitor suppressed survivin levels, induced apoptosis, abolished colony formation in soft agar, and inhibited localized and metastatic tumor growth in mice, without organ or systemic toxicity. In contrast, ER+ breast cancer cells, or various normal cell types, were insensitive to Notch stimulation. Therefore, ER− breast cancer cells become dependent on Notch-survivin signaling for their maintenance, in vivo. Therapeutic targeting of this pathway may be explored for individualized treatment of patients with clinically aggressive, ER− breast cancer. [Cancer Res 2008;68(13):5273–81]
Activation of Protein Kinase G Increases the Expression of p21CIP1, p27KIP1, and Histidine Triad Protein 1 through Sp1
Authors: Cen Bo , Deguchi Atsuko , Weinstein I. Bernard
Published: July 2008

The anticancer role of cyclic guanosine 3′,5′-monophosphate (cGMP)–dependent protein kinase G (PKG) has become of considerable interest, but the underlying mechanisms are not fully established. In this study, we examined the effects of activation of PKG on the expression of three tumor suppressor proteins in human SW480 colon cancer cells. Our results revealed that treatment with cell permeable cGMP derivatives, or the cGMP phosphodiesterase inhibitor sulindac sulfone (exisulind, aptosyn, hereafter called exisulind) led to increased expression of the tumor suppressor proteins p21CIP1, p27KIP1, and Histidine triad protein 1 (HINT1), and their corresponding mRNAs. Overexpression of PKG Iβ also caused increased expression of the p21CIP1, p27KIP1, and HINT1 proteins. Both the p21CIP1 and p27KIP1 promoters contain Sp1 binding sites and they were activated by PKG in luciferase reporter assays. Specific Sp1 sites in the p21 and p27 promoters were sufficient to mediate PKG-induced luciferase reporter activity, suggesting an interaction between Sp1 and PKG. Indeed, we found that PKG can phosphorylate Sp1 on serine residue(s) and this resulted in transcriptional activation of Sp1. Knockdown of Sp1 expression with siRNA inhibited the increased expression of p21CIP1, p27KIP1, and HINT1 induced by the cGMP derivative 8-pCPT-cGMP in SW480 cells. These novel effects of PKG activation on the expression of three tumor suppressor genes may explain, at least in part, the anticancer effects of activation of PKG. They also provide a rationale for further developing activators of PKG for the prevention and treatment of cancer. [Cancer Res 2008;68(13):5355–62]
Zebrafish with Mutations in Mismatch Repair Genes Develop Neurofibromas and Other Tumors
Authors: Feitsma Harma , Kuiper Raoul V. , Korving Jeroen , Nijman Isaac J. , Cuppen Edwin
Published: July 2008

Defective mismatch repair (MMR) in humans causes hereditary nonpolyposis colorectal cancer. This genetic predisposition to colon cancer is linked to heterozygous familial mutations, and loss-of-heterozygosity is necessary for tumor development. In contrast, the rare cases with biallelic MMR mutations are juvenile patients with brain tumors, skin neurofibromas, and café-au-lait spots, resembling the neurofibromatosis syndrome. Many of them also display lymphomas and leukemias, which phenotypically resembles the frequent lymphoma development in mouse MMR knockouts. Here, we describe the identification and characterization of novel knockout mutants of the three major MMR genes, mlh1, msh2, and msh6, in zebrafish and show that they develop tumors at low frequencies. Predominantly, neurofibromas/malignant peripheral nerve sheath tumors were observed; however, a range of other tumor types was also observed. Our findings indicate that zebrafish mimic distinct features of the human disease and are complementary to mouse models. [Cancer Res 2008;68(13):5059–66]
Frequent Inactivation of a Putative Tumor Suppressor, Angiopoietin-Like Protein 2, in Ovarian Cancer
Authors: Kikuchi Ryoko , Tsuda Hitoshi , Kozaki Ken-ichi , Kanai Yae , Kasamatsu Takahiro , Sengoku Kazuo , Hirohashi Setsuo , Inazawa Johji , Imoto Issei
Published: July 2008

Angiopoietin-like protein 2 (ANGPTL2) is a secreted protein belonging to the angiopoietin family, the members of which are implicated in various biological processes, although its receptor remains unknown. We identified a homozygous loss of ANGPTL2 (9q33.3) in the course of screening a panel of ovarian cancer (OC) cell lines for genomic copy-number aberrations using in-house array-based comparative genomic hybridization. ANGPTL2 mRNA expression was observed in normal ovarian tissue and immortalized normal ovarian epithelial cells, but was reduced in some OC lines without its homozygous deletion (18 of 23 lines) and restored after treatment with 5-aza 2′-deoxycytidine. The methylation status of sequences around the ANGPTL2 CpG-island with clear promoter activity inversely correlated with expression. ANGPTL2 methylation was frequently observed in primary OC tissues as well. In an immunohistochemical analysis of primary OCs, ANGPTL2 expression was frequently reduced (51 of 100 cases), and inversely correlated with methylation status. Patients with OC showing reduced ANGPTL2 immunoreactivity had significantly worse survival in the earlier stages (stages I and II), but better survival in advanced stages (stages III and IV). The restoration of ANGPTL2 expression or treatment with conditioned medium containing ANGPTL2 inhibited the growth of OC cells originally lacking the expression of this gene, whereas the knockdown of endogenous ANGPTL2 accelerated the growth of OC cells with the expression of ANGPTL2. These results suggest that, at least partly, epigenetic silencing by hypermethylation of the ANGPTL2 promoter leads to a loss of ANGPTL2 function, which may be a factor in the carcinogenesis of OC in a stage-dependent manner. [Cancer Res 2008;68(13):5067–75]
iASPP Inhibition: Increased Options in Targeting the p53 Family for Cancer Therapy
Authors: Bell Helen S. , Ryan Kevin M.
Published: July 2008

Strategies to induce p53 for cancer therapy offer appeal but many tumors harbor inactivating p53 mutations. One way to address this situation may be to activate the p53-related protein p73, which functions similarly, but unlike p53, is rarely lost or mutated in cancer. Along these lines, a recent study reports that a p53-derived peptide that targets iASPP—a common negative regulator of p53 family members—can effectively trigger tumor cell death by a p73-dependent mechanism. These findings promote further study of iASPP targeting as a therapeutic strategy to activate p73. [Cancer Res 2008;68(13):4959–62]
Functional Genomics Identifies ABCC3 as a Mediator of Taxane Resistance in HER2-Amplified Breast Cancer
Authors: O'Brien Carol , Cavet Guy , Pandita Ajay , Hu Xiaolan , Haydu Lauren , Mohan Sankar , Toy Karen , Rivers Celina Sanchez , Modrusan Zora , Amler Lukas C. , Lackner Mark R.
Published: July 2008

Breast cancer is a heterogeneous disease with distinct molecular subtypes characterized by differential response to targeted and chemotherapeutic agents. Enhanced understanding of the genetic alterations characteristic of different subtypes is needed to pave the way for more personalized administration of therapeutic agents. We have taken a functional genomics approach using a well-characterized panel of breast cancer cell lines to identify putative biomarkers of resistance to antimitotic agents such as paclitaxel and monomethyl-auristatin-E (MMAE). In vitro studies revealed a striking difference in sensitivity to these agents between cell lines from different subtypes, with basal-like cell lines being significantly more sensitive to both agents than luminal or HER2-amplified cell lines. Genome-wide association studies using copy number data from Affymetrix single nucleotide polymorphism arrays identified amplification of the chromosome 17q21 region as being highly associated with resistance to both paclitaxel and MMAE. An unbiased approach consisting of RNA interference and high content analysis was used to show that amplification and concomitant overexpression of the gene encoding the ABCC3 drug transporter is responsible for conferring in vitro resistance to paclitaxel and MMAE. We also show that amplification of ABCC3 is present in primary breast tumors and that it occurs predominantly in HER2-amplified and luminal tumors, and we report on development of a specific fluorescence in situ hybridization assay that may have utility as a predictive biomarker of taxane resistance in breast cancer. [Cancer Res 2008;68(13):5380–9]
Improved Cellular Pharmacokinetics and Pharmacodynamics Underlie the Wide Anticancer Activity of Sagopilone
Authors: Hoffmann Jens , Vitale Ilio , Buchmann Bernd , Galluzzi Lorenzo , Schwede Wolfgang , Senovilla Laura , Skuballa Werner , Vivet Sonia , Lichtner Rosemarie B. , Vicencio José M. , Panaretakis Theocharis , Siemeister Gerhard , Lage Hermann , Nanty Lisa , Hammer Stefanie , Mittelstaedt Kevin , Winsel Sebastian , Eschenbrenner Julia , Castedo Maria , Demarche Carine , Klar Ulrich , Kroemer Guido
Published: July 2008

Sagopilone (ZK-EPO) is the first fully synthetic epothilone undergoing clinical trials for the treatment of human tumors. Here, we investigate the cellular pathways by which sagopilone blocks tumor cell proliferation and compare the intracellular pharmacokinetics and the in vivo pharmacodynamics of sagopilone with other microtubule-stabilizing (or tubulin-polymerizing) agents. Cellular uptake and fractionation/localization studies revealed that sagopilone enters cells more efficiently, associates more tightly with the cytoskeleton, and polymerizes tubulin more potently than paclitaxel. Moreover, in contrast to paclitaxel and other epothilones [such as the natural product epothilone B (patupilone) or its partially synthetic analogue ixabepilone], sagopilone is not a substrate of the P-glycoprotein efflux pumps. Microtubule stabilization by sagopilone caused mitotic arrest, followed by transient multinucleation and activation of the mitochondrial apoptotic pathway. Profiling of the proapoptotic signal transduction pathway induced by sagopilone with a panel of small interfering RNAs revealed that sagopilone acts similarly to paclitaxel. In HCT 116 colon carcinoma cells, sagopilone-induced apoptosis was partly antagonized by the knockdown of proapoptotic members of the Bcl-2 family, including Bax, Bak, and Puma, whereas knockdown of Bcl-2, Bcl-XL, or Chk1 sensitized cells to sagopilone-induced cell death. Related to its improved subcellular pharmacokinetics, however, sagopilone is more cytotoxic than other epothilones in a large panel of human cancer cell lines in vitro and in vivo. In particular, sagopilone is highly effective in reducing the growth of paclitaxel-resistant cancer cells. These results underline the processes behind the therapeutic efficacy of sagopilone, which is now evaluated in a broad phase II program. [Cancer Res 2008;68(13):5301–8]
Berberine Modifies Cysteine 179 of IκBα Kinase, Suppresses Nuclear Factor-κB–Regulated Antiapoptotic Gene Products, and Potentiates Apoptosis
Authors: Pandey Manoj K. , Sung Bokyung , Kunnumakkara Ajaikumar B. , Sethi Gautam , Chaturvedi Madan M. , Aggarwal Bharat B.
Published: July 2008

Berberine, an isoquinoline alkaloid derived from a plant used traditionally in Chinese and Ayurvedic medicine, has been reported to exhibit chemopreventive and anti-inflammatory activities through unknown mechanism. Because of the critical role of the transcription factor nuclear factor-κB (NF-κB) in these processes, we investigated the effect of berberine on this pathway. We found that berberine suppressed NF-κB activation induced by various inflammatory agents and carcinogens. This alkaloid also suppressed constitutive NF-κB activation found in certain tumor cells. Suppression of NF-κB activation occurred through the inhibition of phosphorylation and degradation of IκBα by the inhibition of IκB kinase (IKK) activation, leading to suppression of phosphorylation and nuclear translocation of p65, and finally to inhibition of NF-κB reporter activity. Inhibition of IKK by berbeine was direct and could be reversed by reducing agents. Site-specific mutagenesis suggested the involvement of cysteine residue 179 in IKK. Berberine also suppressed the expression of NF-κB–regulated gene products involved in antiapoptosis (Bcl-xL, Survivin, IAP1, IAP2, and cFLIP), proliferation (cyclin D1), inflammation (cyclooxygenase-2), and invasion (matrix metalloproteinase-9). Suppression of antiapoptotic gene products correlated with enhancement of apoptosis induced by tumor necrosis factor (TNF)-α and chemotherapeutic agents and with inhibition of TNF-induced cellular invasion. Overall, our results indicate that chemopreventive, apoptotic, and anti-inflammatory activities displayed by berberine may be mediated in part through the suppression of the NF-κB activation pathway. This may provide the molecular basis for the ability of berberine to act as an anticancer and anti-inflammatory agent. [Cancer Res 2008;68(13):5370–9]
Loss of the Transmembrane but not the Soluble Kit Ligand Isoform Increases Testicular Germ Cell Tumor Susceptibility in Mice
Authors: Heaney Jason D. , Lam Man-Yee J. , Michelson Megan V. , Nadeau Joseph H.
Published: July 2008

Several genetic variants act as modifiers of testicular germ cell tumor (TGCT) susceptibility in the 129/Sv mouse model of human pediatric TGCTs. One such modifier, the Steel locus, encodes the transmembrane-bound and soluble ligand of the kit receptor. Some (Sl and SlJ) but not all (Sld) mutations of the Steel locus increase TGCT incidence in heterozygous mutant mice. Because Sl and SlJ are large deletions that affect multiple transcripts and Sld is an intragenic deletion of the kit ligand (Kitl) from which only the soluble protein is produced, it was uncertain whether Kitl or a neighboring gene is a modifier of TGCT susceptibility. We tested the effect of the small Steel grizzle-belly (Slgb) deletion on TGCT susceptibility to determine whether Kitl is a TGCT modifier gene. An increase in TGCT incidence was observed in Slgb/+ heterozygotes, and fine mapping of the deletion breakpoints revealed that Kitl is the only conventional gene deleted by the mutation, suggesting that Kitl is the TGCT modifier gene at the Steel locus. Additionally, we propose that soluble KITL in Sld/+ heterozygous mutant mice complements a dosage effect of transmembrane-associated kit ligand on TGCT susceptibility and that the kit receptor (Kit) is haplosufficient for primordial germ cell development. [Cancer Res 2008;68(13):5193–7]
Mitogen-Activated Protein Kinase Activation in Lung Adenocarcinoma: A Comparative Study between Ever Smokers and Never Smokers
Authors: Mountzios Giannis , Planchard David , Besse Benjamin , Validire Pierre , Girard Philippe , Devisme Christine , Dimopoulos Meletios-Athanasios , Soria Jean-Charles , Fouret Pierre
Published: July 2008

Purpose: There are major differences affecting genes in adenocarcinomas in ever and never smokers. However, data on whether mitogen-activated protein kinase (MAPK) activation state differs according to smoking status are limited.

Experimental Design: Expression of activated extracellular signal–regulated kinases, c-Jun NH2-terminal kinases, and P38 enzymes (pP38) were evaluated by means of immunohistochemistry in 188 chemonaïve patients with surgically resected lung adenocarcinoma. Cell viability of the lung adenocarcinoma cell line HCC827 was studied after treatment with cisplatin or the P38 MAPK inhibitor SB 203580.

Results: Thirty-seven of 44 never smokers [84%; 95% confidence intervals (95% CI), 70-92%] expressed high pP38 levels compared with 45 of 104 ever smokers (43%; 95% CI, 34-53%; P < 0.0001). The proportion of never smokers expressing high c-Jun NH2-terminal kinase levels (72%; 95% CI, 57-83%) was greater than that of ever smokers (53%; 95% CI, 44-62%; P = 0.03). The proportion of ever smokers expressing high extracellular signal–regulated kinase levels (51%; 95% CI, 42-59%) was similar to that of never smokers (57%; 95% CI, 42-71%; P = 0.47). Never smokers were 10.5 times (95% CI, 3.5-31.5) more likely to express high pP38 levels after adjustment for variables linked to smoking status, including age, sex, and histologic subtype. None of the activated MAPKs predicted for overall survival. Cell viability of HCC827 was significantly reduced after exposure to SB203580 alone or when combined with cisplatin.

Conclusions: Life-long nonsmoking is associated with high activated P38 levels in patients with lung adenocarcinoma. Activated P38 can contribute to the viability of adenocarcinoma cells in never smokers, but is not predictive for overall survival.
Decreased Expression of Gastrokine 1 and the Trefoil Factor Interacting Protein TFIZ1/GKN2 in Gastric Cancer: Influence of Tumor Histology and Relationship to Prognosis
Authors: Moss Steven F. , Lee Jin-Woo , Sabo Edmond , Rubin Anna K. , Rommel John , Westley Bruce R. , May Felicity E.B. , Gao John , Meitner Patricia A. , Tavares Rose , Resnick Murray B.
Published: July 2008

Purpose: Transcriptional profiling showed decreased expression of gastrokine 1 (GKN1) and the related trefoil factor interacting protein (TFIZ1/GKN2) in Helicobacter pylori infection. Decreased GKN1 and GKN2 mRNA expression has been reported in gastric adenocarcinoma. We have examined GKN1 and GKN2 protein expression in a large gastric cancer series, correlated expression with tumor subtype, and evaluated their utility as prognostic biomarkers.

Experimental Design: GKN1, GKN2, and the trefoil factors TFF1 and TFF3 were examined in tissue microarrays from 155 distal gastric adenocarcinomas. Immunohistochemical expression was correlated with clinical outcome. GKN1 and GKN2 expression was measured by real-time PCR and Western analysis in samples of gastric cancer and adjacent nonneoplastic mucosa.

Results: GKN1 was lost in 78% of diffuse and 42% of intestinal cancers (P < 0.0001, diffuse versus intestinal). GKN2 expression was lost in 85% of diffuse and 54% of intestinal type cancers (P < 0.002). GKN1 and GKN2 down-regulation were confirmed by Western and real-time PCR analysis. Loss of either protein was associated with significantly worse outcome in intestinal-type tumors by univariate analysis; and GKN2 loss remained a predictor of poor outcome in multivariate analysis (P < 0.033). TFF1 was lost in >70%, and TFF3 was expressed in ∼50% of gastric cancers.

Conclusions: Loss of GKN1 and GKN2 expression occurs frequently in gastric adenocarcinomas, especially in the diffuse subtype. GKN1 and GKN2 loss are associated with shorter overall survival in the intestinal subtype.
Positive Correlations of Oct-4 and Nanog in Oral Cancer Stem-Like Cells and High-Grade Oral Squamous Cell Carcinoma
Authors: Chiou Shih-Hwa , Yu Cheng-Chia , Huang Chi-Yang , Lin Shu-Chun , Liu Chung-Ji , Tsai Tung-Hu , Chou Shiu-Huey , Chien Chian-Shiu , Ku Hung-Hai , Lo Jeng-Fan
Published: July 2008

Purpose: Oral squamous cell carcinoma (OSCC), like many solid tumors, contains a heterogeneous population of cancer cells. Recent data suggest that a rare subpopulation of cancer cells, termed cancer stem cells (CSC), is capable of initiating, maintaining, and expanding the growth of tumor. Identification and characterization of CSC from OSCC facilitates the monitoring, therapy, or prevention of OSCC.

Experimental Design: We enriched oral cancer stem-like cells (OC-SLC) through sphere formation by cultivating OSCC cells from established OSCC cell lines or primary cultures of OSCC patients within defined serum-free medium. Differential expression profile of stemness genes between enriched OC-SLC and parental OSCC was elucidated. Furthermore, immunohistochemical staining of stemness markers on OSCC patient tissues was examined to evaluate the association between stemness genes and prognosis of OSCC.

Results: Enriched OC-SLC highly expressed the stem/progenitor cell markers and ABC transporter gene (Oct-4, Nanog, CD117, Nestin, CD133, and ABCG2) and also displayed induced differentiation abilities and enhanced migration/invasion/malignancy capabilities in vitro and in vivo. Elevated expression of CD133 was shown in the enriched OC-SLC from OSCC patients' tumors. Positive correlations of Oct-4, Nanog, or CD133 expression on tumor stage were shown on 52 OSCC patient tissues. Kaplan-Meier analyses exhibited that Nanog/Oct-4/CD133 triple-positive patients predicted the worst survival prognosis of OSCC patients.

Conclusion: We enriched a subpopulation of cancer stem-like cell from OSCC by sphere formation. The enriched OC-SLC possesses the characteristics of both stem cells and malignant tumors. Additionally, expression of stemness markers (Nanog/Oct-4/CD133) contradicts the survival prognosis of OSCC patients.
Bortezomib-Induced Apoptosis with Limited Clinical Response Is Accompanied by Inhibition of Canonical but not Alternative Nuclear Factor-κB Subunits in Head and Neck Cancer
Authors: Allen Clint , Saigal Kunal , Nottingham Liesl , Arun Pattatheyil , Chen Zhong , Van Waes Carter
Published: July 2008

Purpose: Nuclear factor-κB (NF-κB)/REL transcription factors promote cancer cell survival and progression. The canonical (NF-κB1/RELA or cREL) and alternate (NF-κB2/RELB) pathways require the proteasome for cytoplasmic-nuclear translocation, prompting the investigation of bortezomib for cancer therapy. However, limited clinical activity of bortezomib has been observed in many epithelial malignancies, suggesting this could result from incomplete inhibition of NF-κB/RELs or other prosurvival signal pathways.

Experimental Design: To examine these possibilities, matched biopsies from 24 h posttreatment were obtained from accessible tumors of patients who received low-dose bortezomib (0.6 mg/m2) before reirradiation in a phase I trial for recurrent head and neck squamous cell carcinoma (HNSCC). Effects of bortezomib on apoptosis and proliferation by TUNEL and Ki67 staining were compared with nuclear staining for all five NF-κB subunits, phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2), and phosphorylated signal transducers and activators of transcription 3 (STAT3) in tumor biopsies, and by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTP) and DNA binding assay for the five NF-κB subunits in HNSCC cell lines.

Results: HNSCC showed increased nuclear staining for all five NF-κB subunits, phosphorylated ERK1/2, and phosphorylated STAT3. Bortezomib treatment significantly enhanced apoptosis with inhibition of nuclear RELA in three of four tumors, but other NF-κB subunits, ERK1/2, and STAT3 were variably or not affected, and tumor progression was observed within 3 months. In HNSCC cell lines, 10−8 mol/L bortezomib inhibited cell density while inhibiting tumor necrosis factor-α–induced and partially inhibiting basal activation of NF-κB1/RELA, but not NF-κB2/RELB.

Conclusions: Although low-dose bortezomib inhibits activation of subunits of the canonical pathway, it does not block nuclear activation of the noncanonical NF-κB or other prosurvival signal pathways, which may contribute to the heterogeneous responses observed in HNSCC.
Randomized Crossover Pharmacokinetic Study of Solvent-Based Paclitaxel andnab-Paclitaxel
Authors: Gardner Erin R. , Dahut William L. , Scripture Charity D. , Jones Jacquin , Aragon-Ching Jeanny B. , Desai Neil , Hawkins Michael J. , Sparreboom Alex , Figg William D.
Published: July 2008

Purpose: Abraxane (ABI-007) is a 130-nm albumin-bound (nab) particle formulation of paclitaxel, devoid of any additional excipients. We hypothesized that this change in formulation alters the systemic disposition of paclitaxel compared with conventional solvent-based formulations (sb-paclitaxel; Taxol), and leads to improved tolerability of the drug.

Patients and Methods: Patients with malignant solid tumors were randomized to receive the recommended single-agent dose of nab-paclitaxel (260 mg/m2 as a 30-minute infusion) or sb-paclitaxel (175 mg/m2 as a 3-hour infusion). After cycle 1, patients crossed over to the alternate treatment. Pharmacokinetic studies were carried out for the first cycle of sb-paclitaxel and the first two cycles of nab-paclitaxel.

Results: Seventeen patients were treated, with 14 receiving at least one cycle each of nab-paclitaxel and sb-paclitaxel. No change in nab-paclitaxel pharmacokinetics was found between the first and second cycles (P = 0.95), suggesting limited intrasubject variability. Total drug exposure was comparable between the two formulations (P = 0.55) despite the dose difference. However, exposure to unbound paclitaxel was significantly higher after nab-paclitaxel administration, due to the increased free fraction (0.063 ± 0.021 versus 0.024 ± 0.009; P < 0.001).

Conclusion: This study shows that paclitaxel disposition is subject to considerable variability depending on the formulation used. Because systemic exposure to unbound paclitaxel is likely a driving force behind tumoral uptake, these findings explain, at least in part, previous observations that the administration of nab-paclitaxel is associated with augmented antitumor efficacy compared with solvent-based paclitaxel.
Effect of Food on the Pharmacokinetic Behavior of the Potent Oral Taxane BMS-275183
Authors: Bröker Linda E. , Valdivieso Manual , Pilat Mary Jo , DeLuca Pamela , Zhou Xiaofei , Parker Susan , Giaccone Giuseppe , LoRusso Patricia M.
Published: July 2008

Purpose: BMS-275183 is a potent oral paclitaxel analogue that previously showed promising activity. The goal of the present trial was to investigate whether food affects the pharmacokinetics of BMS-275183. Additionally, we evaluated its pharmacokinetic variability using flat-fixed dosing compared with dosing individualized by body surface area (BSA).

Patients and Methods: The patients were treated with 200 mg of BMS-275183 under fasting condition (A), after a standard low-fat meal (B), or after a high-fat meal (C). The patients were randomized to one of six treatment sequences (ABC, ACB, BAC, BCA, CAB, or CBA). The fourth (D) and consecutive weekly doses were normalized by BSA and consisted of 200 mg/m2. Pharmacokinetic sampling was done up to 72 hours after the first four doses and analyzed with a validated liquid chromatography/mass spectrometry assay.

Results: A total of 31 patients were treated. Pharmacokinetic data were available for 26 patients (A and C), 24 patients (B), and 21 patients (D). Compared with administration under fasted conditions, a decrease of 39% and 63% in the maximal observed drug concentration was observed when BMS-275183 was administered after a low-fat and a high-fat meal, respectively. There was no change in systemic exposure as measured by the area under the plasma concentration versus time curve extrapolated to infinity (AUCinf). No apparent relationship was observed between AUCinf and BSA for either the 200 mg or the 200 mg/m2 regimen. BMS-275183 was well tolerated with grade 3 and 4 toxicity in eight patients. One partial response was observed in a non–small cell lung cancer patient.

Conclusions: Food intake does not affect the pharmacologic exposure to BMS-275183. BMS-275183 can be given orally by flat dosing instead of BSA-normalized dosing.
Synergistic Inhibition of ErbB Signaling by Combined Treatment with Seliciclib and ErbB-Targeting Agents
Authors: Fleming Ian N. , Hogben Morag , Frame Sheelagh , McClue Steven J. , Green Simon R.
Published: July 2008

Purpose: The aims of this study were to investigate whether the cyclin-dependent kinase inhibitor seliciclib could synergize with agents that target ErbB receptors and to elucidate the molecular mechanism of the observed synergy.

Experimental Design: Synergy between seliciclib and ErbB receptor targeted agents was investigated in various cell lines using the Calcusyn median effect model. The molecular mechanism of the observed synergy was studied in cultured cells, and the combination of seliciclib and the epidermal growth factor receptor (EGFR) inhibitor erlotinib was evaluated in an H358 xenograft model.

Results: Seliciclib synergized with the anti-HER2 antibody trastuzumab in a breast cancer cell line, which overexpresses the HER2 receptor, and with the erlotinib analogue AG1478 in non–small cell lung cancer cell lines. In the H358 non–small cell lung cancer cell line, synergy involved decreased signaling from the EGFR, with AG1478 directly inhibiting kinase activity while seliciclib decreased the levels of key components of the receptor signaling pathway, resulting in enhanced loss of phosphorylated extracellular signal-regulated kinase and cyclin D1. The combination of seliciclib and erlotinib was evaluated further in an H358 xenograft and shown to be significantly more active than either agent alone. An enhanced loss of cyclin D1 was also seen in vivo.

Conclusions: This is the first report that investigates combining seliciclib with an EGFR inhibitor. The combination decreased signaling from the EGFR in vitro and in vivo and was effective in cell lines containing either wild-type or mutant EGFR, suggesting that it may expand the range of tumors that respond to erlotinib, and therefore, such combinations are worth exploring in the clinic.