bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract B57: Regulation of Eag expression by p53 and Rb in tumoral cells
Authors: Chavez-Lopez Maria de Guadalupe , Garcia-Villa Enrique , Gariglio Patricio , Garrido E. , Hernandez-Gallegos Elizabeth , Ponce Veronica , Camacho Javier 
Published: May 2012

Abstract
Introduction: Ether à go-go (Eag) potassium channels display oncogenic properties. Their expression in healthy tissues is limited almost exclusively to the brain; however, it is highly expressed in several types of cancer. In addition, the inhibition of its activity or expression remarkably diminishes cellular proliferation and tumor progression. Our group found the expression of Eag in cells having alterations in p53 and Rb including C-33 and HeLa from cervical cancer. On the other hand, we have observed that Eag gene expression is regulated by factors that inhibit Rb or p53, such as, E6 and E7 oncogenes of the human papilloma virus and estradiol. Therefore, we have considered p53 and Rb like possible pathways for Eag regulation. To our knowledge, there are no reports on Eag regulation by tumor suppressor proteins. Thus in this work we evaluated the effect of p53 and Rb overexpression on the expression of Eag in C-33, HeLa (cervix) and A549 (lung cancer) cells. We also analyzed the expression of Eag in tumor samples from patients with retinoblastoma (a malignant tumor characterized by the loss of the gene Rb and alterations in the p53 pathway).
Methods: C-33, HeLa and A549 cells were obtained from American Type Culture Collection (ATCC) and the RNA's of patients with retinoblastoma from the Hospital of Pediatrics of the Medical Centre XXI century. In order to evaluate the expression of Eag, retrotranscription was performed and the analysis of gene expression was carried out by real time PCR, the results were analyzed by the method of ΔΔ-CT. In order to evaluate the effect of p53 and Rb overexpression on Eag, HeLa and C-33 cells were grown in DMEM and A549 cells on F12-K medium, supplemented with 10% of bovine fetal serum; later they were transfected with 1 µg of plasmid containing p53 and/or Rb. The RNA was obtained 72 hours later and then subjected to retrotranscription. Eag gene expression was then analyzed by real time PCR.
Results: We found that p53 and Rb transfection in C-33 cells does not affect the expression of Eag. However, Eag expression in HeLa cells was clearly down-regulated when transfected with p53 and/or Rb. Transfection of p53 in A549 cells diminished the expression of Eag, in contrast to Rb transfection which increased expression. Interestingly, we observed a very high expression of Eag in samples of retinoblastoma in comparison with the Eag expression in HeLa cells and in normal retina.
Conclusions: Our results suggest that tumor suppressor proteins p53 and Rb regulate the expression of Eag. In addition, our results also suggest Eag as a retinoblastoma potential therapeutic target for this type of tumors.
This project was partially supported by ICyT DF.
Citation Information: Cancer Res 2009;69(23 Suppl):B57.
Abstract B6: Revealing DAPK1 transcriptional regulation by RNA interference screening with an integrated BAC-reporter system
Authors: Oakes Christopher C. , Park Yoon Jung , Boutros Michael , Plass Christoph 
Published: May 2012

Abstract
High-throughput RNA interference screening has been used successfully to reveal novel gene function. Currently used expression reporter systems employ small constructs of synthetic or endogenous sequences containing pathway-specific response elements. The use of these small reporter systems does not allow for the recapitulation of the regulatory complexity that controls an individual gene of interest. Death-associated protein kinase 1 (DAPK1) is a tumor suppressor gene that is silenced in a broad variety of cancers. Specifically, we have previously found DAPK1 to be silenced in virtually all cases of chronic lymphocytic leukemia and silencing is associated with promoter DNA methylation. Although epigenetic silencing is indicative of a transcriptional defect, the basis for this silencing is unknown. Here, we have employed a novel approach to elucidate genes involved in the transcriptional regulation of DAPK1. Using BAC recombineering and stable transgene integration, we have engineered human cells to express a DAPK1-luciferase reporter under the control of approximately 180 Kb of sequence surrounding the DAPK1 transcriptional start site. By performing genome-wide siRNA high-throughout screening, we have been able to determine candidate genes involved in DAPK1 regulation. We have also performed screens in parallel using small, plasmid-based promoter reporter constructs by transient transfection and stable integration. Evaluation of these reporter systems has revealed significant drawbacks of plasmid-based reporters which include nonspecific effects arising from proximal vector backbone sequences. In conclusion, an integrated BAC-reporter system is useful for the assessment of gene-specific transcriptional regulation. Future work will involve determining the disease-specific roles for novel DAPK1 regulatory genes.
Citation Information: Cancer Res 2009;69(23 Suppl):B6.
Abstract B67: A mechanistic link between whole-chromosome aneuploidy and DNA damage
Authors: Crasta Karen , Nezi Luigi , Hennessy Morgan , Cameron Lisa , Pan Yunfeng , Chowdhury Dipanjan , Pellman David 
Published: May 2012

Abstract
Cancer is associated with aneuploidy—both structural defects in chromosomes and abnormal numbers of intact chromosomes. The contribution of chromosome breaks to tumorigenesis is well accepted because of the possibility of generating cancer-causing mutations. However, the role of alterations of intact chromosome numbers remains a subject of debate, principally because mechanisms by which whole chromosome aneuploidy would affect cancer pathogenesis are poorly understood. We now have evidence to support one mechanism by which whole chromosome aneuploidy can lead to DNA breaks, via mis-segregation of chromosomes into micronuclei, structures commonly observed in cancer cells. Micronuclei containing intact chromosomes can form after mitotic errors, when the nuclear envelope reforms around a lagging chromosome. We have developed procedures to monitor the fate of micronuclei. Strikingly, whole chromosome-containing micronuclei develop evidence of DNA breaks during the first S phase after they are formed. Blocking DNA replication blocks the formation of these breaks. Defective DNA replication may be due to defective nucleocytoplasmic transport because micronuclei display a marked defect in assembling nuclear pore complexes. These findings suggest one mechanism by which mitotic errors result in DNA damage and thus potentially promote tumorigenesis.
Citation Information: Cancer Res 2009;69(23 Suppl):B67.
Abstract B69: SUMO-binding proteins as effectors and regulators of SUMO modification
Authors: Guzzo Catherine M. , Uzoma Ijeoma , Zhu Heng , Cox Eric , Blackshaw Seth , Matunis Michael J. 
Published: May 2012

Abstract
SUMOs (Small Ubiquitin-related Modifiers) are reversibly conjugated to other proteins in the cell, thereby regulating a wide range of essential functions. Many of the functions regulated by SUMOylation are intimately tied to processes directly relevant to cancer, including maintenance of genome integrity and cell cycle regulation. Studies in the past several years have in fact linked SUMOylation to a variety of human cancers, including leukemia, prostrate, breast, and colon cancers. In addition, SUMOylation has a direct role in promoting cancer metastasis. Thus, developing a fundamental understanding of the signals and factors that regulate SUMOylation, as well as how SUMOylation affects protein function, has the potential to lead to important new insights into cancer development, diagnosis, and treatment. We hypothesize that the three SUMO paralogues expressed in vertebrate cells (SUMO-1, SUMO-2 and SUMO-3), as well as their polymeric forms, represent unique signals recognized by unique proteins. Moreover, we propose that SUMOylation often promotes interactions between modified proteins and downstream factors containing SUMO-interacting motifs (SIMs). To test this hypothesis, we have initiated high throughput studies to identify novel SUMO-1, SUMO-2 and SUMO-2 polymeric chain binding proteins. Using protein microarray analysis, we identified ∼400 mostly nuclear proteins, many with preferential affinity for specific SUMO paralogues. Among these 400 putative SUMO-binding proteins was a family of zinc finger proteins that we have determined to possess a novel SIM. This family includes human proteins ZNF261, ZNF198, ZNF237, ZNF262, and ZNF258 and each protein contains a stretch of unique tandem zinc fingers called MYM (myeloproliferative and mental retardation) domains. Although the exact functions of MYM-type zinc finger motifs are not known, proteins containing these motifs are linked to myeloproliferative syndromes, X-linked mental retardation, and transcriptional regulation. We have found that although ZNF261 contains four canonical SIMs, these SIMs do not mediate SUMO binding. Rather, analysis of a series of truncation mutants of ZNF261 revealed that the MYM-type zinc finger motifs are both necessary and sufficient for SUMO-binding. MYM-type zinc finger motifs represent only the second known class of SUMO-binding motifs.
Citation Information: Cancer Res 2009;69(23 Suppl):B69.
Abstract B74: A microRNA expression signature of response to EGFR inhibition targets EMT in both lung and pancreatic cell lines
Authors: Balko Justin M. , Coakley Virginia L. , Britson Joel S. , Willian Michael C. , Frolov Andrey , Black Esther P. 
Published: May 2012

Abstract
Purpose: The intent of the study described herein is to develop and characterize a microRNA gene expression signature of response to EGFR inhibition portable to solid tumors for which treatment with an EGFR inhibitor is indicated.
Experimental Design: Treatment with inhibitors of the epidermal growth factor receptor (EGFR) can result in clinical response in both non-small cell lung cancer (NSCLC) and pancreatic ductal adenocarcinoma (PDAC), but only in a minority of unselected patients. Identification of biomarkers that can direct treatment to the responsive population is essential and here we describe generation of a microRNA gene signature of response to EGFR inhibition. Using a Taqman MicroRNA Array of 381 probes, we demonstrate that a 20-gene microRNA signature derived from NSCLC cell lines can predict sensitivity of both lung and pancreatic cancer cell lines to erlotinib, a small molecule inhibitor of EGFR. Overlap of independently generated microRNA expression signatures of NSCLC and pancreatic cell lines produces a fourgene signature. We characterize a target of the reduced signature, ZEB1, in NSCLC and pancreatic cancer cell lines by evaluation of mRNA and protein expression. We evaluated ZEB1 protein and the ZEB1 target, E-cadherin, after transfection of mir-200c into inhibitor-resistant NSCLC cell line, A549.
Results: We have identified a 20-gene microRNA signature of response to EGFR inhibition that predicts both inhibitor-sensitive NSCLC and pancreatic cell lines. By overlapping independent signatures of response in NSCLC and pancreatic cancer cell lines, a four gene microRNA signature is identified that targets proteins responsible for epithelial to mesenchymal transition (EMT). Of those proteins, ZEB1 is a transcription factor responsible for repression of E-cadherin expression. Both ZEB1 mRNA and protein expression are down-regulated in erlotinib-sensitive NSCLC in which the microRNA genes 200b, 200c, and 141 are up-regulated. Ectopic expression of mir-200c in inhibitor-resistant lines induces cell death, suggesting that down-regulation of this microRNA is essential for viability in these NSCLC lines.
Conclusions: The 20-gene miRNA signature of sensitivity provides a means for defining response that can be generated from FFPE samples of tumor rather than fresh tumor samples. Whereas mRNA is difficult to isolate from FFPE samples due to degradation, microRNA may survive the fixation process. Thus, response to EGFR inhibition in the second- or third-line can be predicted from fixed tumor samples collected early in the treatment of an individual patient, eliminating the need for acquisition of fresh tumor. Further, the microRNA signature identifies the well-studied EMT pathway indicative of EGFR-inhibitor sensitivity and provides biological significance for the members of the signature.
Citation Information: Cancer Res 2009;69(23 Suppl):B74.
Abstract B77: Chk1-Lats2-14-3-3 is a novel signaling pathway that regulates the P-body formation in response to DNA damage
Authors: Okada Nobuhiro , Yabuta Norikazu , Nojima Hiroshi 
Published: May 2012

Abstract
Purpose: Lats2 (Large tumor suppressor 2), a member of the conserved Lats kinase family, is a human tumor suppressor gene. We previously reported that Lats2 knockout in mice displays embryonic lethality and the MEFs from Lats2−/− mice causes mitotic defects including centrosome fragmentation and cytokinesis defects associated with nuclear enlargement and multinucleation. DNA damage response (DDR) plays an essential role in maintaining the integrity of the genome and is crucial for cancer avoidance. The purpose of this study is to investigate the role of Lats2 in DDR, which prevents chromosome instability and malignant progression of human cancer by keeping the chromosome stability. MicroRNAs (miRNAs), endogenous RNAs of approximately 22 nucleotides, play an important role in the regulation of gene expression: miRNAs are incorporated into miRNA-induced silencing complexes (miRISCs), which leads to either cleavage or translational repression of targeted mRNAs. mRNA processing bodies (P-bodies) are sites where untranslated mRNAs accumulate, and mRNA degradation, translational repression, and mRNA surveillance take place.
Methods: We raised two phospho-specific antibodies against the phosphorylation sites of Lats2 by Chk1 and 14-3-3 by Lats2 to analyze the phosphorylation status and localization by Western blot and immunocytochemical analyses. Moreover, we established myc-tagged U2OS/siLats2 strains that stably expressed Lats2 mutated the phosphorylation site to alanine or aspartic acid, and examined the effects of those on DNA damage signaling pathway.
Results: We found that Lats2 is phophorylated by Chk1 and/or Chk2 in response to DNA damage, which induced the phosphorylation of 14-3-3 by Lats2. Immunocytochemical analysis using a phospho-specific antibody against 14-3-3 revealed that the phosphorylated 14-3-3 localized to the P-body, and these signals are enhanced in response to DNA damage. We propose here that 14-3-3 is a novel regulatory protein for P-body formation that promotes the miRNA-mediated gene silencing. Indeed, depletion of 14-3-3 or Lats2 reduced the localization to the P-body of both 14-3-3 and a putative P-body scaffold protein, GW182. Eventually, this pathway regulates the translesion synthesis (TLS), a process that synthesizes DNA across DNA lesion, through p21 translational repression by miRNA.
Conclusion: We conclude that Chk1-Lats2-14-3-3 axis is a novel DNA damage signaling pathway that regulates the P-body assembly, thereby causing the translational repression of target genes via miRNA. These results provide the first evidence for a mechanism in which the DNA damage response pathway regulates miRNA-mediated translational repression through P-body assembly.
Citation Information: Cancer Res 2009;69(23 Suppl):B77.
Abstract B8: The two isoforms of ADAM9 have opposing roles in breast cancer cell migration
Authors: Fry Jessica L. , Toker Alex 
Published: May 2012

Abstract
Tumor cell migration is a complex event mediated by the genetic characteristics of the tumor cells themselves in cooperation with changes in the tissue microenvironment. ADAM9, a member of a family of transmembrane matrix-metalloproteases named for their integrin-binding Disintegrin And Metalloprotease domains, is implicated in cell-cell and cell-matrix interactions as well as in shedding of receptors and ligands. ADAM9 is present in breast cancer tumors and cell lines as two alternatively spliced isoforms—ADAM9-L and the truncated, secreted, ADAM9-S. We find that ADAM9-S is expressed primarily in the more migratory basal subtype of breast cancer cell lines, and exogenous and endogenous overexpression of ADAM9-S increases breast cancer cell migration, leading to our hypothesis that ADAM9 present in the breast tumor environment mediates tumor cell migration. Using lentiviral-shRNA constructs, we silenced expression of endogenous human ADAM9 protein in the BT549, ZR75-1 and CAMA-1 breast cancer cell lines, resulting in an increase in cell migration measured by transwell assay. This enhanced migration is reversed by reintroduction of ADAM9-L protein into these cells, while reintroduction of ADAM9-S enhances this migration phenotype in a metalloprotease-dependent manner, showing opposing roles for the two isoforms of ADAM9 in breast cancer cell migration. Furthermore, analysis of functional domain mutants of ADAM9-L shows that ADAM9-L suppresses cell migration in a metalloprotease-independent manner. We also find that ADAM9-L expression alters the migratory phenotype of α-6 integrin-blocking antibody GOH-indicating a role for ADAM9-L in integrin signaling. Future analysis of the proteolytic substrates of ADAM9-S, as well as the subcellular localization and downstream signaling of ADAM9-will further illuminate the mechanisms by which ADAM9 isoforms differentially mediate cell migration.
Citation Information: Cancer Res 2009;69(23 Suppl):B8.
Abstract C11: CD117 and Stro-1 identify osteosarcoma stem cells associated with metastasis and chemotherapy-drug resistance
Authors: Adhikari Amit S. , Agarwal Neeraj , Wood Byron M. , Porretta Constance , Ruiz Bernardo , Pochampally Radhika , Iwakuma Tomoo 
Published: May 2012

Abstract
Osteosarcoma, the most common bone cancer, is the second highest cause of cancer-related death in children and adolescents. Approximately 90% of cases show micro-metastasis at diagnosis, making systematic chemotherapy the first choice of treatment. Despite intensive chemotherapy, the survival rate for high-grade osteosarcomas remains only 50-80%. The inadequacy of current treatments may result from the inability to effectively target cancer stem cells (CSCs) or tumor initiating cells (TI-Cs) of osteosarcoma. Thus, novel therapies targeting cancer stem cells (CSCs) in osteosarcoma is an urgent requirement for eradicating this dreadful disease. Here, we have identified mouse and human osteosarcoma CSCs using mesenchymal stem cell markers CD117 and Stro-1. These markers were preferentially expressed in spheres and doxorubicin-resistant cells. CD117+Stro-1+ cells efficiently formed serially transplantable tumors, whereas CD117-Stro-1-cells rarely initiated tumors. Upon orthotopic injections, CD117+Stro-1+-derived tumors metastasized at a high frequency. Further, CD117+Stro-1+ cells were capable of differentiating into adipogenic lineage, and were enriched for CXCR4 and ABCG2, respectively associated with metastasis and drug-resistance. Thus, CD117 and Stro-1 identify osteosarcoma CSCs with the most lethal characteristics of the disease—metastasis and drug-resistance—proposing these markers as potential candidates for CSC-targeted drug delivery towards eradication of osteosarcoma.
Citation Information: Cancer Res 2009;69(23 Suppl):C11.
Abstract C12: EGFR signaling controls the chromatin binding status of BMI1 through a CK2/PP1 phosphorylation/dephosphorylation pathway and affects astrocytoma proliferation and neural stem cell differentiation
Authors: Hawes Jessica H. , Tuskan Robert G. , Agaki Keiko , Reilly Karlyne M. 
Published: May 2012

Abstract
Studies of brain tumors demonstrate the importance of a rare tumor cell population with the capability of regenerating tumors upon transplantation. These cancer stem cells (CSC) are believed to be more resistant to therapy than the bulk of brain tumor cells. Studies in mouse brain tumor models demonstrate that neural stem cells (NSC) can be an important initiating cell type for brain tumors, but the relationship between NSC and CSC is unclear. EGF is a critical growth factor for NSC maintenance in culture and EGFR signaling is upregulated in glioblastoma. Similarly, the chromatin modulator BMI1 is necessary for NSC maintenance, and has been implicated in glioblastoma. We present studies linking cell surface EGF signaling and nuclear BMI1 chromatin binding. We demonstrate that BMI1 is specifically phosphorylated by EGFR signaling using EGF and TGFα, but not by other ligands tested. We have identified three amino acids encompassing the phosphorylation site in response to EGFR signaling, and show that CK2 and PP1 are necessary for control of BMI1 phosphorylation. This phosphorylation alters the chromatin binding state of BMI1 and transcriptional regulation in astrocytoma cells. Interestingly we find that BMI1 can alter transcriptional profiles in both EGF-dependent and independent ways, suggesting that different signaling pathways could have specific effects on changing the BMI1-dependent epigenetic state of subsets of genes. Furthermore, EGF-induced phosphorylation of BMI1 is important for astrocytoma growth in vitro and in vivo, as well as maintenance of NSC.
Our data link signals outside the cell to the nucleus important for NSC maintenance and astrocytoma proliferation. These data represent a common pathway in NSC and CSC that may explain the importance of EGF signaling for NSC maintenance and gliomagenesis, and suggest a novel downstream pathway (CK2/PP1) involved in these processes.
Citation Information: Cancer Res 2009;69(23 Suppl):C12.