bluuebunny/crossref_metadata_2025 huggingface dataset:
Real-time Detection of Gene Expression in Cancer Cells Using Molecular Beacon Imaging: New Strategies for Cancer Research
Authors: Peng Xiang-Hong , Cao Ze-Hong , Xia Jin-Tang , Carlson Grant W. , Lewis Melinda M. , Wood William C. , Yang Lily
Published: September 2005

Development of novel approaches for quantitative analysis of gene expression in intact tumor cells should provide new means for cancer detection and for studying the response of cancer cells to biological and therapeutic reagents. We developed procedures for detecting the levels of expression of multiple genes in fixed as well as viable cells using molecular beacon imaging technology. We found that simultaneous delivery of molecular beacons targeting survivin and cyclin D1 mRNAs produced strong fluorescence in breast cancer but not in normal breast cells. Importantly, fluorescence intensity correlated well with the level of gene expression in the cells detected by real-time reverse transcription–PCR or Western blot analysis. We further show that molecular beacons can detect changes of survivin gene expression in viable cancer cells following epidermal growth factor stimulation, docetaxel treatment, and overexpression of p53 gene. Thus, molecular beacon imaging is a simple and specific method for detecting gene expression in cancer cells. It has great potential for cancer detection and drug development.
Targeted Replacement of Hypoxia-Inducible Factor-1α by a Hypoxia-Inducible Factor-2α Knock-in Allele Promotes Tumor Growth
Authors: Covello Kelly L. , Simon M. Celeste , Keith Brian
Published: September 2005

Hypoxia-inducible factors (HIF) are essential transcriptional regulators that mediate adaptation to hypoxic stress in rapidly growing tissues such as tumors. HIF activity is regulated by hypoxic stabilization of the related HIF-1α and HIF-2α subunits, which are frequently overexpressed in cancer cells. To assess the relative tumor-promoting functions of HIF-1α and HIF-2α directly, we replaced HIF-1α expression with HIF-2α by creating a novel “knock-in” allele at the Hif-1α locus through homologous recombination in primary murine embryonic stem cells. Compared with controls, s.c. teratomas derived from knock-in embryonic stem cells were larger and more proliferative, had increased microvessel density, and exhibited increased expression of vascular endothelial growth factor, transforming growth factor-α, and cyclin D1. These and other data indicate that HIF-2α promotes tumor growth more effectively than HIF-1α in multiple contexts.
Conditional BRAFV600E Expression Induces DNA Synthesis, Apoptosis, Dedifferentiation, and Chromosomal Instability in Thyroid PCCL3 Cells
Authors: Mitsutake Norisato , Knauf Jeffrey A. , Mitsutake Shin , Mesa Cleo , Zhang Lei , Fagin James A.
Published: September 2005

The activating mutation BRAFT1796A is the most prevalent genetic alteration in papillary thyroid carcinomas (PTC). It is associated with advanced PTCs, suggesting that this oncoprotein confers thyroid cancers with more aggressive properties. BRAFT1796A is also observed in thyroid micropapillary carcinomas and may thus be an early event in tumor development. To explore its biological consequences, we established doxycycline-inducible BRAFV600E-expressing clonal lines derived from well-differentiated rat thyroid PCCL3 cells. Expression of BRAFV600E did not induce growth in the absence of thyrotropin despite increasing DNA synthesis, which is likely explained because of a concomitant increase in apoptosis. Thyrotropin-dependent cell growth and DNA synthesis were reduced by BRAFV600E because of decreased thyrotropin responsiveness associated with inhibition of thyrotropin receptor gene expression. These results are similar to those obtained following conditional expression of RET/PTC. However, in contrast to RET/PTC, BRAF activation did not impair key activation steps distal to the thyrotropin receptor, such as forskolin-induced adenylyl cyclase activity or cyclic AMP–induced DNA synthesis. We reported previously that acute RET/PTC expression in PCCL3 cells did not induce genomic instability. By contrast, induction of BRAFV600E expression increased the frequency of micronuclei by both clastogenic and aneugenic events. These data indicate that BRAFV600E expression confers thyroid cells with little growth advantage because of concomitant activation of DNA synthesis and apoptosis. However, in contrast to RET/PTC, BRAFV600E may facilitate the acquisition of secondary genetic events through induction of genomic instability, which may account for its aggressive properties.
p53CSV, a Novel p53-Inducible Gene Involved in the p53-Dependent Cell-Survival Pathway
Authors: Park Woong-Ryeon , Nakamura Yusuke
Published: September 2005

Although a number of p53 target genes have been identified, the mechanisms of p53-dependent activities that determine cellular survival or death are still not fully understood. Here we report isolation of a novel p53 target gene, designated p53-inducible cell-survival factor (p53CSV). p53CSV contains a p53-binding site within its second exon and the reduction of expression by small interfering RNA enhanced apoptosis, whereas overexpression protected cells from apoptosis caused by DNA damage. p53CSV is induced significantly when cells have a low level of genotoxic stresses, but not when DNA damage is severe. p53CSV can modulate apoptotic pathways through interaction with Hsp70 that probably inhibits activity of apoptosis protease activating factor-1. Our results imply that under specific conditions of stress, p53 regulates transcription of p53CSV and that p53CSV is one of the important players in the p53-mediated cell survival.
Discovery of Aberrant Expression of R-RAS by Cancer-Linked DNA Hypomethylation in Gastric Cancer Using Microarrays
Authors: Nishigaki Michiko , Aoyagi Kazuhiko , Danjoh Inaho , Fukaya Masahide , Yanagihara Kazuyoshi , Sakamoto Hiromi , Yoshida Teruhiko , Sasaki Hiroki
Published: September 2005

Although hypomethylation was the originally identified epigenetic change in cancer, it was overlooked for many years in preference to hypermethylation. Recently, gene activation by cancer-linked hypomethylation has been rediscovered. However, in gastric cancer, genome-wide screening of the activated genes has not been found. By using microarrays, we identified 1,383 gene candidates reactivated in at least one cell line of eight gastric cancer cell lines after treatment with 5-aza-2′deoxycytidine and trichostatin A. Of the 1,383 genes, 159 genes, including oncogenes ELK1, FRAT2, R-RAS, RHOB, and RHO6, were further selected as gene candidates that are silenced by DNA methylation in normal stomach mucosa but are activated by DNA demethylation in a subset of gastric cancers. Next, we showed that demethylation of specific CpG sites within the first intron of R-RAS causes activation in more than half of gastric cancers. Introduction of siRNA into R-RAS-expressing cells resulted in the disappearance of the adhered cells, suggesting that functional blocking of the R-RAS-signaling pathway has great potential for gastric cancer therapy. Our extensive gene list provides other candidates for this class of oncogene.
CD4+ T Cells Are Able to Promote Tumor Growth through Inhibition of Tumor-Specific CD8+ T-Cell Responses in Tumor-Bearing Hosts
Authors: den Boer Annemieke Th. , van Mierlo Geertje J.D. , Fransen Marieke F. , Melief Cornelis J.M. , Offringa Rienk , Toes René E.M.
Published: September 2005

Modulation of the immune response by established tumors may contribute to the limited success of therapeutic vaccination for the treatment of cancer compared with vaccination in a preventive setting. We analyzed the contribution of the CD4+ T-cell population to the induction or suppression of tumor-specific CD8+ T cells in a tumor model in which eradication of tumors crucially depends on CD8+ T cell–mediated immunity. Vaccine-mediated induction of protective antitumor immunity in the preventive setting (i.e., before tumor challenge) was CD4+ T cell dependent because depletion of this T-cell subset prevented CD8+ T-cell induction. In contrast, depletion of CD4+ cells in mice bearing established E1A+ tumors empowered the mice to raise strong CD8+ T-cell immunity capable of tumor eradication without the need for tumor-specific vaccination. Spontaneous eradication of tumors, which had initially grown out, was similarly observed in MHC class II–deficient mice, supporting the notion that the tumor-bearing mice harbor a class II MHC–restricted CD4+ T-cell subset capable of suppressing a tumor-specific CD8+ T-cell immune response. The deleterious effects of the presence of CD4+ T cells in tumor-bearing hosts could be overcome by CD40-triggering or injection of CpG. Together these results show that CD4+ T cells with a suppressive activity are rapidly induced following tumor development and that their suppressive effect can be overcome by agents that activate professional antigen-presenting cells. These observations are important for the development of immune interventions aiming at treatment of cancer.
Tumor Suppressor Activity and Epigenetic Inactivation of Hepatocyte Growth Factor Activator Inhibitor Type 2/SPINT2 in Papillary and Clear Cell Renal Cell Carcinoma
Authors: Morris Mark R. , Gentle Dean , Abdulrahman Mahera , Maina Esther N. , Gupta Kunal , Banks Rosamonde E. , Wiesener Michael S. , Kishida Takeshi , Yao Masahiro , Teh Bin , Latif Farida , Maher Eamonn R.
Published: September 2005

Following treatment with a demethylating agent, 5 of 11 renal cell carcinoma (RCC) cell lines showed increased expression of hepatocyte growth factor (HGF) activator inhibitor type 2 (HAI-2/SPINT2/Bikunin), a Kunitz-type protease inhibitor that regulates HGF activity. As activating mutations in the MET proto-oncogene (the HGF receptor) cause familial RCC, we investigated whether HAI-2/SPINT2 might act as a RCC tumor suppressor gene. We found that transcriptional silencing of HAI-2 in RCC cell lines was associated with promoter region methylation and HAI-2/SPINT2 protein expression was down-regulated in 30% of sporadic RCC. Furthermore, methylation-specific PCR analysis revealed promoter region methylation in 30% (19 of 64) of clear cell RCC and 40% (15 of 38) of papillary RCC, whereas mutation analysis (in 39 RCC cell lines and primary tumors) revealed a missense substitution (P111S) in one RCC cell line. Restoration of HAI-2/SPINT2 expression in a RCC cell line reduced in vitro colony formation, but the P111S mutant had no significant effect. Increased cell motility associated with HAI-2/SPINT2 inactivation was abrogated by treatment with extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) and phospholipase C-γ inhibitors, but not by an inhibitor of atypical protein kinase C. These findings are consistent with frequent epigenetic inactivation of HAI-2/SPINT2, causing loss of RCC tumor suppressor activity and implicate abnormalities of the MET pathway in clear cell and papillary sporadic RCC. This information provides opportunities to develop novel targeted approaches to the treatment of RCC.
Identification of Metastasis-Associated Receptor Tyrosine Kinases in Non–Small Cell Lung Cancer
Authors: Müller-Tidow Carsten , Diederichs Sven , Bulk Etmar , Pohle Thorsten , Steffen Björn , Schwäble Joachim , Plewka Sylvia , Thomas Michael , Metzger Ralf , Schneider Paul M. , Brandts Christian H. , Berdel Wolfgang E. , Serve Hubert
Published: September 2005

Development of distant metastasis after tumor resection is the leading cause of death in early-stage non–small cell lung cancer (NSCLC). Receptor tyrosine kinases (RTK) are involved in tumorigenesis but only few RTKs have been systematically studied in NSCLC. Here, we provide quantitative real-time reverse transcription-PCR expression data of all RTKs (n = 56) in primary tumors of 70 patients with early-stage (I-IIIA) NSCLC. Overall, 33 RTKs were expressed in at least 25% of the patients. Several RTKs were significantly expressed higher in tumors that ultimately metastasized. The hazard risk for metastasis development in stage I/II disease was increased at least 3-fold for tumors with high expression levels of insulin receptor, neurotrophic tyrosine receptor kinase 1, epidermal growth factor receptor, ERBB2, ERBB3, platelet-derived growth factor receptor β, fibroblast growth factor receptor 1, or leukocyte tyrosine kinase. Relative risks were reduced 3-fold by expression of EPHB6 or DKFZ1. Three members of the epidermal growth factor receptor family were associated with a high risk of metastasis, emphasizing the validity of our data. High ERBB3 expression was significantly associated with decreased survival. Taken together, our genome-wide RTK expression map uncovered the previously unknown value of several RTKs as potential markers for prognosis and metastasis prediction in early-stage NSCLC. The identified RTKs represent promising novel candidates for further functional analyses.
Functional Loss of the γ-Catenin Gene through Epigenetic and Genetic Pathways in Human Prostate Cancer
Authors: Shiina Hiroaki , Breault Julia E. , Basset William W. , Enokida Hideki , Urakami Shinji , Li Long-Cheng , Okino Steven T. , Deguchi Masao , Kaneuchi Masanori , Terashima Masaharu , Yoneda Tatsuaki , Shigeno Kazushi , Carroll Peter R. , Igawa Mikio , Dahiya Rajvir
Published: September 2005

γ-Catenin is a cell adhesion molecule and a candidate mediator of Wnt signal transduction. We hypothesized that impaired regulation of γ-catenin through genetic and epigenetic pathways is associated with the pathogenesis of prostate cancer. To test this hypothesis, cytosine-phosphate-guanine methylation, loss of heterozygosity (LOH), and mutation status of the γ-catenin gene were analyzed in cultured prostate cancer cell lines, 180 localized prostate cancers, 69 benign prostatic hyperplasias, and 11 hormone refractory prostate cancers (HRPC). In prostate cancer cell lines (DuPro, LNCaP, ND-1, and PC3), γ-catenin mRNA transcripts were increased after 5-aza-2′-deoxycytidine treatment. In localized prostate cancer, γ-catenin expression was lower but prevalence of γ-catenin methylation was higher compared with benign prostatic hyperplasia. However, γ-catenin methylation did not correlate with Gleason sum, pT category, or capsular penetration. Among localized prostate cancers with positive γ-catenin methylation, the presence of LOH at chromosome 17q21 was closely related to down-regulation of γ-catenin mRNA expression. The γ-catenin mutations were not found in localized prostate cancers, whereas six mutations were found in five HRPCs within or close to the GSK-3β consensus motif phosphorylation site, among which four HRPCs showed strong nuclear γ-catenin accumulation. In these four HRPCs, Bcl-2 expression was increased, whereas the target of the Wnt signal, c-myc, was only expressed in one HRPC. Therefore, although epigenetic γ-catenin methylation is an early event in the development of prostate cancer, simultaneous events of epigenetic cytosine-phosphate-guanine methylation and genetic LOH may be responsible for functional loss of γ-catenin. The γ-catenin mutation related to Bcl-2 overexpression has a significant effect on the pathogenesis of HRPC. This is the first report to characterize the epigenetic and genetic regulation of γ-catenin in human prostate cancer.
Functional Idiotopes: Tumor Antigen–Directed Expression of CD8+ T-Cell Epitopes Nested in Unique NH2-terminal VH Sequence of Antiidiotypic Antibodies?
Authors: Kawano Kouichiro , Ferrone Soldano , Ioannides Constantin G.
Published: September 2005

Antiidiotypic antibodies have been and are being used for cancer immunotherapy based on the rationale that Ab2 carrying an “internal image” of the corresponding tumor antigen can induce tumor antigen–specific antibodies (i.e., Ab3 and inhibit tumor growth). Recent evidence indicates that Ab2 also induces cellular responses by CD4+ and CD8+ T cells. This finding has raised the question of where the short peptides, which express CD8+ T-cell–defined epitopes, are located and their relationship with the tumor antigen. We found that two of the four known Ab2 associated with tumor antigen, with known amino acid sequence, express unique NH2-terminal VH sequences which precede the framework regions. Both the unique and the shared NH2-terminal VH sequences are nested MHC class I antigen–binding peptides. These peptides were highly homologous with peptides from corresponding tumor antigen (carcinoembryonic antigen, CD55, and human high molecular weight melanoma–associated antigen) but differed from the tumor antigen peptides by the presence of the side chain known to mediate stronger forces of interaction with other atoms. The presence of candidate CTL epitopes in NH2-terminal VH of Ab2 homologous with tumor antigen may be important for the development of novel immunotherapeutic strategies for cancer.
Pulmonary Radiation Injury: Identification of Risk Factors Associated with Regional Hypersensitivity
Authors: Novakova-Jiresova Alena , van Luijk Peter , van Goor Harry , Kampinga Harm H. , Coppes Robert P.
Published: September 2005

Effective radiation treatment of thoracic tumors is often limited by radiosensitivity of surrounding tissues. Several experimental studies have suggested variations in radiosensitivity of different pulmonary regions. Mice and rat studies in part contradict each other and urge for a more detailed analysis. This study was designed to obtain a more comprehensive insight in radiation injury development, expression, and its regional heterogeneity in lung. The latter is obviously highly critical for optimization of radiotherapy treatment plans and may shed light on the mechanisms of lung dysfunction after irradiation. Six different but volume-equal regions in rat lung were irradiated. Whereas the severity of damage, as seen in histologic analysis, was comparable in all regions, the degree of lung dysfunction, measured as breathing rates, largely varied. During the pneumonitic phase (early: 6-12 weeks), the most sensitive regions contained a substantial part of alveolar lung parenchyma. Also, a trend for hypersensitivity was observed when the heart lay in the irradiation field. In the fibrotic phase (late: 34-38 weeks), lung parenchyma and heart-encompassing regions were the most sensitive. No impact of the heart was observed during the intermediate phase (16-28 weeks). The severity of respiratory dysfunction after partial thoracic irradiation is likely governed by an interaction between pulmonary and cardiac functional deficits. As a repercussion, more severe acute and delayed toxicity should be expected after combined lung and heart irradiation. This should be considered in the process of radiotherapy treatment planning of thoracic malignancies.
Estrogen Receptor–Binding Fragment–Associated Antigen 9 Is a Tumor-Promoting and Prognostic Factor for Renal Cell Carcinoma
Authors: Ogushi Tetsuo , Takahashi Satoru , Takeuchi Takumi , Urano Tomohiko , Horie-Inoue Kuniko , Kumagai Jinpei , Kitamura Tadaichi , Ouchi Yasuyoshi , Muramatsu Masami , Inoue Satoshi
Published: September 2005

The estrogen receptor–binding fragment–associated antigen 9 (EBAG9) has been identified as a primary estrogen-responsive gene in human breast cancer MCF7 cells. A high expression of EBAG9 has been observed in invasive breast cancer and advanced prostate cancer, suggesting a tumor-promoting role of the protein in malignancies. Here we show that intratumoral (i.t.) administration of small interfering RNA against EBAG9 exerted overt regression of tumors following s.c. implantation of murine renal cell carcinoma (RCC) Renca cells. Overexpression of EBAG9 did not promote the proliferation of culture Renca cells; however, the inoculated Renca cells harboring EBAG9 (Renca-EBAG9) in BALB/c mice grew faster and developed larger tumors compared with Renca cells expressing vector alone (Renca-vector). After renal subcapsular implantation, Renca-EBAG9 tumors significantly enlarged compared with Renca-vector tumors in BALB/c mice, whereas both Renca-EBAG9 and Renca-vector tumors were developed with similar volumes in BALB/c nude mice. No apparent difference was observed in specific cytotoxic T-cell responses against Renca-EBAG9 and Renca-vector cells; nonetheless, the number of infiltrating CD8+ T lymphocytes was decreased in Renca-EBAG9 subcapsular tumors. Furthermore, immunohistochemical study of EBAG9 in 78 human RCC specimens showed that intense and diffuse cytoplasmic immunostaining was observed in 87% of the cases and positive EBAG9 immunoreactivity was closely correlated with poor prognosis of the patients. Multivariate analysis revealed that high EBAG9 expression was an independent prognostic predictor for disease-specific survival (P = 0.0485). Our results suggest that EBAG9 is a crucial regulator of tumor progression and a potential prognostic marker for RCC.
Synergy of Epidermal Growth Factor Receptor Kinase Inhibitor AG1478 and ErbB2 Kinase Inhibitor AG879 in Human Colon Carcinoma Cells Is Associated with Induction of Apoptosis
Authors: Zhou Yunfei , Brattain Michael G.
Published: September 2005

Previous studies have shown that constitutive activation of epidermal growth factor receptor (EGFR) and ErbB2 by elevated autocrine transforming growth factor-α (TGF-α) expression plays an important role in colon cancer progression. Coexpression of EGFR and ErbB2 is found in a subset of colon cancers and may cooperatively promote cancer cell growth and survival, as heterodimerization is known to provide for diversification of signal transduction. In this study, the EGFR-selective tyrosine kinase inhibitor (TKI) AG1478 inhibited cell growth of an aggressive human colon carcinoma cell line, FET6αS26X, which harbors constitutively activated EGFR after stable transfection with TGF-α cDNA. However, AG1478 failed to induce apoptosis in FET6αS26X cells at concentrations sufficient for cell growth inhibition and complete suppression of EGFR phosphorylation. Similarly, AG879, a selective ErbB2 TKI, was incapable of inducing apoptosis in FET6αS26X cells at concentrations sufficient to inhibit cell growth and ErbB2 phosphorylation. To test the hypothesis that targeting both ErbB family members would show better efficacy than targeting the single receptors, combinations of inhibitors at fixed ratios of 1:1, 5:1, and 10:1 of AG1478 and AG879, respectively, were compared with single drugs for inhibition of cell growth. All combinations resulted in synergistic effects as indicated by combination index analysis. Synergistic inhibition was associated with induction of apoptosis as reflected by poly(ADP-ribose) polymerase cleavage, caspase-3 activation, and Annexin V staining. Finally, Western blot analysis showed significant inhibition of phosphorylation of both EGFR and ErbB2 by the combination treatment. These data suggest that the strategy to target both EGFR and ErbB2 simultaneously might result in more efficient inhibition of tumor growth than to target single receptor alone.
Assessment of a Combined, Adenovirus-Mediated Oncolytic and Immunostimulatory Tumor Therapy
Authors: Bernt Kathrin Maria , Ni Shaoheng , Tieu Anh-Thu , Lieber André
Published: September 2005

In this study, we identified murine breast cancer cell lines that support DNA replication of E1-deleted adenovirus vectors and which can be killed by an oncolytic adenovirus expressing adenovirus E1A and tumor necrosis factor (TNF)–related apoptosis inducing ligand (TRAIL) in a replication-dependent manner (Ad.IR-E1A/TRAIL). We showed that systemic or intratumoral (i.t.) injection of adenovirus vectors into mice increases plasma levels of proinflammatory cytokines and chemokines, including TNF-α, INF-γ, and MCP-1, which are potent inducers of dendritic cell maturation. Furthermore, we showed that in vivo expression of Flt3L from an adenovirus vector increases the number of CD11b+ and CD11c+ cells (populations that include dendritic cells) in the blood circulation. Based on these findings, we tested whether Ad.IR-E1A/TRAIL induced killing of tumor cells in combination with dendritic cell mobilization by Ad.Flt3L or, for comparison, Ad.GM-CSF would have an additive antitumor effect. As a model, we used immunocompetent C3H mice with syngeneic s.c. tumors derived from C3L5 cells. We found that vaccination of mice with C3L5 cells that underwent viral oncolysis in combination with Flt3L or granulocyte-macrophage colony-stimulating factor (GM-CSF) expression induces a systemic antitumor immune response. I.t. injection of the oncolytic and Flt3L expressing vectors into established tumors delayed tumor growth but did not cause efficient tumor elimination. This study shows the effectiveness of a combined oncolytic/immunostimulatory tumor therapy approach.
Cell Type-Specific Tumor Suppression by Ink4a and Arf in Kras-Induced Mouse Gliomagenesis
Authors: Uhrbom Lene , Kastemar Marianne , Johansson Fredrik K. , Westermark Bengt , Holland Eric C.
Published: September 2005

Homozygous deletion of the INK4a-ARF locus is one of the most frequent mutations found in human glioblastoma. We have previously shown that combined Ink4a-Arf loss can increase tumor incidence in both glial progenitor cells and astrocytes during mouse gliomagenesis. Here we have investigated the separate contribution of loss of each of the tumor suppressor genes in glial progenitor cells and astrocytes in Akt + Kras–induced gliomagenesis. We show that Arf is the major tumor suppressor gene in both cell types. Arf loss generated glioblastomas from both nestin-expressing glial progenitor cells and glial fibrillary acidic protein–expressing astrocytes, with a significantly higher incidence in astrocytes. Ink4a loss, on the other hand, could only significantly contribute to gliomagenesis from glial progenitor cells and the induced tumors were of lower malignancy than those seen in Arf-deficient mice. Thus, Ink4a and Arf have independent and differential tumor suppressor functions in vivo in the glial cell compartment.
Interleukin 6 Supports the Maintenance of p53 Tumor Suppressor Gene Promoter Methylation
Authors: Hodge David R. , Peng Benjamin , Cherry James C. , Hurt Elaine M. , Fox Stephen D. , Kelley James A. , Munroe David J. , Farrar William L.
Published: September 2005

A strong association exists between states of chronic inflammation and cancer, and it is believed that mediators of inflammation may be responsible for this phenomenon. Interleukin 6 (IL-6) is an inflammatory cytokine known to play a role in the growth and survival of many types of tumors, yet the mechanisms employed by this pleomorphic cytokine to accomplish this feat are still poorly understood. Another important factor in tumor development seems to be the hypermethylation of CpG islands located within the promoter regions of tumor suppressor genes. This common epigenetic alteration enables tumor cells to reduce or inactivate the expression of important tumor suppressor and cell cycle regulatory genes. Here we show that in the IL-6–responsive human multiple myeloma cell line KAS 6/1, the promoter region of p53 is epigenetically modified by methyltransferases, resulting in decreased levels of expression. Furthermore, cells treated with IL-6 exhibit an increase in the expression of the DNA maintenance methylation enzyme, DNMT-1. The DNA methyltransferase inhibitor zebularine reverses the methylation of the p53 promoter, allowing the resumption of its expression. However, when zebularine is withdrawn from the cells, the reestablishment of the original CpG island methylation within the p53 promoter does not occur in the absence of IL-6, and cells which do not receive IL-6 eventually die, as p53 expression continues unchecked by remethylation. Interestingly, this loss of viability seems to involve not the withdrawal of cytokine, but the inability of the cell to resilence the promoter. Consistent with this model, when cells that express IL-6 in an autocrine fashion are subjected to identical treatment, p53 expression is reduced shortly after withdrawal of zebularine. Therefore, it seems IL-6 is capable of maintaining promoter methylation thus representing one of the possible mechanisms used by inflammatory mediators in the growth and survival of tumors.
Aberrant Stat3 Signaling by Interleukin-4 in Malignant Glioma Cells: Involvement of IL-13Rα2
Authors: Rahaman Shaik Ohidar , Vogelbaum Michael A. , Haque S. Jaharul
Published: September 2005

Interleukin (IL)-4 exhibits antitumor activity in rodent experimental gliomas, which is likely mediated by the actions of IL-4 on a variety of immune cells present in and around the tumor masses. Here, we show that IL-4, which activates Stat6 in normal human astrocytes and in a variety of other cells, induces an aberrant activation of Stat3 in glioblastoma multiforme (GBM) cells but not in normal human astrocytes. Previously, we have shown that autocrine IL-6 signaling induces a persistent activation of Stat3. Now, we show that Stat3 is further activated by IL-4 stimulation of GBM cells. Expression of IL-13Rα2, a decoy receptor for IL-13 that partly blocks IL-4–mediated activation of Stat6 in GBM cells, up-regulates the activation of Stat3 as shown by a small interfering RNA–mediated inhibition of IL-13Rα2 expression. In addition, transient expression of the IL-13Rα2 transgene in 293T cells increases the IL-4–mediated activation of Stat3 and subsequent expression of Stat3-targeted gene. Coimmunoprecipitation results reveal that IL-13Rα2–mediated activation of Stat3 does not require a direct physical interaction between Stat3 and IL-13Rα2. Chromatin immunoprecipitation assay employing anti-Stat3 antibody confirms the in vivo binding of activated Stat3 to the promoters of genes that encode antiapoptotic proteins Bcl-2, Bcl-xL, and Mcl-1. IL-4 significantly up-regulates of the steady-state levels of Bcl-2, Bcl-xL, and Mcl-1 in GBM cells. These results indicate that IL-4/IL-13 receptor-mediated Stat3 signaling may contribute to the pathogenesis of GBM cells by modulating the expression of the Bcl-2 family of antiapoptotic proteins.
Genetic and Pharmacologic Identification of Akt as a Mediator of Brain-Derived Neurotrophic Factor/TrkB Rescue of Neuroblastoma Cells from Chemotherapy-Induced Cell Death
Authors: Li Zhijie , Jaboin Jerry , Dennis Phillip A. , Thiele Carol J.
Published: September 2005

Patients whose neuroblastoma tumors express high levels of brain-derived neurotrophic factor (BDNF) and TrkB have an unfavorable prognosis. Our previous studies indicated that BDNF activation of the TrkB signal transduction pathway blocked the cytotoxic effects of chemotherapeutic drugs via the phosphatidylinositol 3-kinase pathway. Akt is an important downstream target of phosphatidylinositol 3-kinase and functions to regulate cell survival, proliferation, and protein synthesis. In this study, we examined whether Akt is required and sufficient to mediate BDNF/TrkB protection of neuroblastoma cells from chemotherapy. Transient transfection of a constitutively active Akt (Akt-Myr) into TrkB-expressing SY5Y cells (TB8 cells) increases Akt activation and attenuates the cell death induced by chemotherapeutic reagents in the absence of BDNF. Furthermore, expression of a dominant-negative Akt (Akt-K179A) blocks the ability of BDNF to rescue TB8 cells from chemotherapy-induced cell death. Pharmacologic inhibition of Akt, with PIA6, a phosphatidylinositol ether lipid analogue (PIA), blocks BDNF-induced phosphorylation of Akt and the downstream target of Akt. PIA6 sensitizes neuroblastoma cells to chemotherapy and attenuates BDNF protection of neuroblastoma cells from chemotherapy-induced cell death. These results indicate that Akt is a key signaling component by which BDNF activation of the TrkB signal transduction pathway protects neuroblastoma cells from chemotherapy-induced cell death. This study raises the possibility that novel pharmacologic inhibitors of Akt may enhance the effectiveness of chemotherapeutic agents in the treatment of neuroblastoma tumors.
Bax and Bak Are Required for Apoptosis Induction by Sulforaphane, a Cruciferous Vegetable–Derived Cancer Chemopreventive Agent
Authors: Choi Sunga , Singh Shivendra V.
Published: September 2005

Sulforaphane, a constituent of many edible cruciferous vegetables, including broccoli, effectively suppresses proliferation of cancer cells in culture and in vivo by causing apoptosis induction, but the sequence of events leading to cell death is poorly defined. Here, we show that multidomain proapoptotic Bcl-2 family members Bax and Bak play a critical role in apoptosis induction by sulforaphane. This conclusion is based on the following observations: (a) sulforaphane treatment caused a dose- and time-dependent increase in the protein levels of both Bax and Bak and conformational change and mitochondrial translocation of Bax in SV40-transformed mouse embryonic fibroblasts (MEF) derived from wild-type mice to trigger cytosolic release of apoptogenic molecules (cytochrome c and Smac/DIABLO), activation of caspase-9 and caspase-3, and ultimately cell death; (b) MEFs derived from Bax or Bak knockout mice resisted cell death by sulforaphane, and (c) MEFs derived from Bax and Bak double knockout mice exhibited even greater protection against sulforaphane-induced cytochrome c release, caspase activation, and apoptosis compared with wild-type or single knockout cells. Interestingly, sulforaphane treatment also caused a dose- and time-dependent increase in the protein level of Apaf-1 in wild-type, Bax−/−, and Bak−/− MEFs but not in double knockout, suggesting that Bax and Bak might regulate sulforaphane-mediated induction of Apaf-1 protein. A marked decline in the protein level of X-linked inhibitor of apoptosis on treatment with sulforaphane was also observed. Thus, it is reasonable to postulate that sulforaphane-induced apoptosis is amplified by a decrease in X-linked inhibitor of apoptosis level, which functions to block cell death by inhibiting activities of caspases. In conclusion, the results of the present study indicate that Bax and Bak proteins play a critical role in initiation of cell death by sulforaphane.
An Expression-Based Site of Origin Diagnostic Method Designed for Clinical Application to Cancer of Unknown Origin
Authors: Tothill Richard W. , Kowalczyk Adam , Rischin Danny , Bousioutas Alex , Haviv Izhak , van Laar Ryan K. , Waring Paul M. , Zalcberg John , Ward Robyn , Biankin Andrew V. , Sutherland Robert L. , Henshall Susan M. , Fong Kwun , Pollack Jonathan R. , Bowtell David D.L. , Holloway Andrew J.
Published: September 2005

Gene expression profiling offers a promising new technique for the diagnosis and prognosis of cancer. We have applied this technology to build a clinically robust site of origin classifier with the ultimate aim of applying it to determine the origin of cancer of unknown primary (CUP). A single cDNA microarray platform was used to profile 229 primary and metastatic tumors representing 14 tumor types and multiple histologic subtypes. This data set was subsequently used for training and validation of a support vector machine (SVM) classifier, demonstrating 89% accuracy using a 13-class model. Further, we show the translation of a five-class classifier to a quantitative PCR–based platform. Selecting 79 optimal gene markers, we generated a quantitative-PCR low-density array, allowing the assay of both fresh-frozen and formalin-fixed paraffin-embedded (FFPE) tissue. Data generated using both quantitative PCR and microarray were subsequently used to train and validate a cross-platform SVM model with high prediction accuracy. Finally, we applied our SVM classifiers to 13 cases of CUP. We show that the microarray SVM classifier was capable of making high confidence predictions in 11 of 13 cases. These predictions were supported by comprehensive review of the patients' clinical histories.
The Integrity of the Charged Pocket in the BTB/POZ Domain Is Essential for the Phenotype Induced by the Leukemia-Associated t(11;17) Fusion Protein PLZF/RARα
Authors: Puccetti Elena , Zheng Xiaomin , Brambilla Daria , Seshire Anita , Beissert Tim , Boehrer Simone , Nürnberger Heike , Hoelzer Dieter , Ottmann Oliver Gerhard , Nervi Clara , Ruthardt Martin
Published: September 2005

Acute myeloid leukemia is characterized by a differentiation block as well as by an increased self-renewal of hematopoietic precursors in the bone marrow. This phenotype is induced by specific acute myeloid leukemia–associated translocations, such as t(15;17) and t(11;17), which involve an identical portion of the retinoic acid receptor α (RARα) and either the promyelocytic leukemia (PML) or promyelocytic zinc finger (PLZF) genes, respectively. The resulting fusion proteins form high molecular weight complexes and aberrantly bind several histone deacetylase–recruiting nuclear corepressor complexes. The amino-terminal BTB/POZ domain is indispensable for the capacity of PLZF to form high molecular weight complexes. Here, we studied the role of dimerization and binding to histone deacetylase–recruiting nuclear corepressor complexes for the induction of the leukemic phenotype by PLZF/RARα and we show that (a) the BTB/POZ domain mediates the oligomerization of PLZF/RARα; (b) mutations that inhibit dimerization of PLZF do the same in PLZF/RARα; (c) the PLZF/RARα-related block of differentiation requires an intact BTB/POZ domain; (d) the mutations interfering with either folding of the BTB/POZ domain or with its charged pocket prevent the self-renewal of PLZF/RARα-positive hematopoietic stem cells. Taken together, these data provide evidence that the dimerization capacity and the formation of a functionally charged pocket are indispensable for the PLZF/RARα-induced leukemogenesis.
Generation and Molecular Characterization of Head and Neck Squamous Cell Lines of Fanconi Anemia Patients
Authors: van Zeeburg Hester J.T. , Snijders Peter J.F. , Pals Gerard , Hermsen Mario A.J.A. , Rooimans Martin A. , Bagby Grover , Soulier Jean , Gluckman Eliane , Wennerberg Johan , Leemans C. René , Joenje Hans , Brakenhoff Ruud H.
Published: September 2005

Patients with Fanconi anemia (FA) are prone to develop malignancies at an early age. Besides hematologic malignancies, squamous cell carcinomas in the anogenital region and head and neck are also frequently found in these patients. The aim of this study was to generate a panel of head and neck squamous cell carcinoma (HNSCC) cell lines and xenografts of FA HNSCC, and to characterize these cell lines in comparison with a panel of seven cell lines from patients with sporadic HNSCC. Analyses have been done on sensitivity to DNA cross-linking agents, loss of heterozygosity profile, TP53 mutations, TP53 polymorphisms and the presence of human papillomavirus. Four FA HNSCC cell lines were established. Sensitivity to DNA cross-linking agents (cisplatin) in the FA HNSCC cell lines was on average 10 times higher as compared with the sporadic HNSCC cell lines. Human papillomavirus was not detected in any of the FA or sporadic cell lines. No differences were found in loss of heterozygosity pattern, TP53 mutation frequency and TP53 polymorphism between FA and sporadic HNSCC cell lines. This is the first report on the generation of squamous cell lines of FA patients. The FA HNSCC cell lines we have generated may be utilized for future studies and might aid in the development of new preventive therapies for FA patients. The genetic characteristics of these cell lines suggest that FA HNSCC are not very different from sporadic HNSCC, except for the sensitivity to cisplatin which is consistent with the known cellular FA phenotype.
Gene Therapy for Prostate Cancer by Controlling Adenovirus E1a and E4 Gene Expression with PSES Enhancer
Authors: Li Xiong , Zhang Yan-Ping , Kim Hong-Sup , Bae Kyung-Hee , Stantz Keith M. , Lee Sang-Jin , Jung Chaeyong , Jiménez Juan A. , Gardner Thomas A. , Jeng Meei-Huey , Kao Chinghai
Published: September 2005

PSES is a chimeric enhancer containing enhancer elements from prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSMA) genes that are prevalently expressed in androgen-independent prostate cancers. PSES shows strong activity equivalent to cytomegalovirus (CMV) promoter, specifically in PSA/PSMA-positive prostate cancer cells, the major cell types in prostate cancer in the absence of androgen. We developed a recombinant adenovirus (AdE4PSESE1a) by placing adenoviral E1a and E4 genes under the control of the bidirectional enhancer PSES and enhanced green fluorescent protein gene for the purpose of intratumoral virus tracking under the control of CMV promoter. Because of PSES being very weak in nonprostatic cells, including HEK293 and HER911 that are frequently used to produce recombinant adenovirus, AdE4PSESE1a can only be produced in the HER911E4 cell line which expresses both E1 and E4 genes. AdE4PSESE1a showed similar viral replication and tumor cell killing activities to wild-type adenovirus in PSA/PSMA-positive prostate cancer cells. The viral replication and tumor cell killing activities were dramatically attenuated in PSA/PSMA-negative cells. To test whether AdE4PSESE1a could be used to target prostate tumors in vivo, CWR22rv s.c. tumors were induced in nude mice and treated with AdE4PSESE1a via intratumoral and tail vein injection. Compared to tumors treated with control virus, the growth of CWR22rv tumors was dramatically inhibited by AdE4PSESE1a via tail vein injection or intratumoral injection. These data show that adenoviral replication can be tightly controlled in a novel fashion by controlling adenoviral E1a and E4 genes simultaneously with a single enhancer.
Reconstitution of Human Telomerase Reverse Transcriptase Expression Rescues Colorectal Carcinoma Cells from In vitro Senescence: Evidence against Immortality as a Constitutive Trait of Tumor Cells
Authors: Dalerba Piero , Guiducci Cristiana , Poliani Pietro Luigi , Cifola Ingrid , Parenza Mariella , Frattini Milo , Gallino Gianfrancesco , Carnevali Ileana , Di Giulio Ilvia , Andreola Salvatore , Lombardo Claudia , Rivoltini Licia , Schweighoffer Tamás , Belli Filiberto , Colombo Mario P. , Parmiani Giorgio , Castelli Chiara
Published: September 2005

Although in vitro establishment of new colorectal carcinoma (CRC) cell lines is an infrequent event, we have observed that primary cultures of CRC can be repeatedly and reproducibly initiated following in vitro plating of tumor-derived epithelial cells. These cultures, however, usually display a short life span as they undergo a limited number of cell passages before entering a state of irreversible growth arrest. In this study, we show that short-lived CRC primary cultures lack constitutive telomerase activity and undergo a senescence process characterized by progressive telomere shortening. Moreover, transduction of these cells with a retroviral vector encoding human telomerase reverse transcriptase (hTERT) is sufficient to reconstitute telomerase activity and allow immortalization. Detailed molecular characterization of hTERT-immortalized CRC cell lines confirms their individual tumor origin by showing expression of colonic epithelial differentiation markers, such as cytokeratin-20 (CK20), full match with class I and class II human leukocyte antigen genotyping of autologous B-lymphoblastoid cells, and presence of somatic mutations in key cancer genes (KRAS2, APC) identical to those of the corresponding autologous original tumor tissues. Moreover, functional characterization of hTERT-immortalized CRC cell lines shows that they have a transformed phenotype, being able to form colonies in soft agar and tumors in severe combined immunodeficient mice. Most interestingly, immunohistochemical analysis of original tumor tissues indicates that short-lived CRC primary cultures, although hTERT-negative in vitro, derive from hTERT-positive tumors. Taken together, our data show that, in a least subset of CRC, biochemical pathways involved in maintenance of telomere length, such as telomerase, are not activated in a constitutive way in all tumor cells.
Mitochondrial-Mediated Disregulation of Ca2+ Is a Critical Determinant of Velcade (PS-341/Bortezomib) Cytotoxicity in Myeloma Cell Lines
Authors: Landowski Terry H. , Megli Christina J. , Nullmeyer Kevin D. , Lynch Ronald M. , Dorr Robert T.
Published: September 2005

The proteasome inhibitor bortezomib (also known as PS-341/Velcade) is a dipeptidyl boronic acid that has recently been approved for use in patients with multiple myeloma. Bortezomib inhibits the activity of the 26S proteasome and induces cell death in a variety of tumor cells; however, the mechanism of cytotoxicity is not well understood. In this report, oligonucleotide microarray analysis of the 8226 multiple myeloma cell line showed a predominant induction of gene products associated with the endoplasmic reticulum secretory pathway following short-term, high-dose exposure to bortezomib. Examination of mediators of endoplasmic reticulum stress–induced cell death showed specific activation of caspase 12, as well as of caspases 8, 9, 7, and 3, and cleavage of bid. Treatment of myeloma cells with bortezomib also showed disregulation of intracellular Ca2+ as a mechanism of caspase activation. Cotreatment with a panel of Ca2+-modulating agents identified the mitochondrial uniporter as a critical regulatory factor in bortezomib cytotoxicity. The uniporter inhibitors ruthenium red and Ru360 prevented caspase activation and bid cleavage, and almost entirely inhibited bortezomib-induced cell death, but had no effect on any other chemotherapeutic drug examined. Additional Ca2+-modulating agents, including 2-amino-ethoxydiphenylborate, 1,2-bis (o-aminophenoxy) ethane-tretraacetic acid (acetoxymethyl) ester, and dantrolene, did not alter bortezomib cytotoxicity. Analysis of intracellular Ca2+ showed that the ruthenium-containing compounds inhibited Ca2+ store loading and abrogated the desensitized capacitative calcium influx associated with bortezomib treatment. These data support the hypothesis that intracellular Ca2+ disregulation is a critical determinant of bortezomib cytotoxicity.
Early Growth Response 1 Acts as a Tumor SuppressorIn vivoandIn vitrovia Regulation of p53
Authors: Krones-Herzig Anja , Mittal Shalu , Yule Kelly , Liang Hongyan , English Chris , Urcis Rafael , Soni Tarun , Adamson Eileen D. , Mercola Dan
Published: September 2005

The early growth response 1 (Egr1) gene is a transcription factor that acts as both a tumor suppressor and a tumor promoter. Egr1-null mouse embryo fibroblasts bypass replicative senescence and exhibit a loss of DNA damage response and an apparent immortal growth, suggesting loss of p53 functions. Stringent expression analysis revealed 266 transcripts with >2-fold differential expression in Egr1-null mouse embryo fibroblasts, including 143 known genes. Of the 143 genes, program-assisted searching revealed 66 informative genes linked to Egr1. All 66 genes could be placed on a single regulatory network consisting of three branch points of known Egr1 target genes: TGFβ1, IL6, and IGFI. Moreover, 19 additional genes that are known targets of p53 were identified, indicating that p53 is a fourth branch point. Electrophoretic mobility shift assay as well as chromatin immunoprecipitation confirmed that p53 is a direct target of Egr1. Because deficient p53 expression causes tumors in mice, we tested the role of Egr1 in a two-step skin carcinogenesis study (144 mice) that revealed a uniformly accelerated development of skin tumors in Egr1-null mice (P < 0.005). These studies reveal a new role for Egr1 as an in vivo tumor suppressor.