bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractA 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 However, when zebularine is withdrawn from the cells, the reestablishment of the original CpG island methylation within the p53 promoter does not occur in the absence of IL-6, and cells which do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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

AbstractThe 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 &gt;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 &lt; 0.005). These studies reveal a new role for Egr1 as an in vivo tumor suppressor.
Inhibition of DNA Repair by a Herpes Simplex Virus Vector Enhances the Radiosensitivity of Human Glioblastoma Cells
Authors: Hadjipanayis Costas G. , DeLuca Neal A. 
Published: September 2005

Abstract
Expression of the herpes simplex virus (HSV) protein, ICP0, from the viral genome, rendered two radioresistant human glioblastoma multiforme cell lines more sensitive to the effects of ionizing radiation. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and clonogenic survival assays, U87-MG and T98 cell survival was more greatly decreased as a function of ionizing radiation dose when ICP0 was preexpressed in cells compared with when ICP0 was not expressed. Consistent with previous results, we found that the catalytic subunit of DNA-dependent protein kinase was degraded as a function of ICP0 in both cell types. This most likely resulted in the inhibition of DNA repair as inferred by the persistence of γH2AX foci or DNA double-strand breaks. Enhanced apoptosis was also found to occur following irradiation of U87-MG cells preinfected with the ICP0-producing HSV-1 mutant, d106. Our results suggest that expression of ICP0 in human glioblastoma multiforme cells inhibits the repair of DNA double-strand breaks after ionizing radiation treatment, decreasing the survival of these cells in part by induction of apoptosis.