bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract B21: Defining the DNA damage response-mediated barrier to ErbB2-induced transformation of somatic mammary cells in vivo
Authors: Reddy Jay P. , Peddibhotla Sirisha , Bu Wen , Zhao Jing , Haricharan Svasti , Du Yi-Chieh Nancy , Podyspanina Katrina , Rosen Jeffrey M. , Donehower Larry A. , Li Yi 
Published: May 2012

Abstract
The DNA damage response (DDR) represents a signaling cascade, which is comprised of DNA damage sensors (such as γH2AX and 53BP1), ATM, Chk2, p53, among others, that becomes activated when confronted with DNA double strand breaks and other forms of DNA damage. The activation of the DDR, in addition to the ARF pathway, has recently been found to elicit apoptosis and senescence in response to oncogene activation. However, the significance of a DDR in blocking cancer progression has not been tested in breast carcinogenesis. Preneoplastic lesions in four germline transgenic models of breast cancer that express polyoma middle T antigen (PyMT), ErbB2, c-Myc, or H-Ras do not exhibit a DDR. We have previously reported a novel mouse model of mammary cancer, where oncogenes can be introduced into somatic mammary epithelial cells via retroviral infection of RCAS vectors into MMTV-tva mice (termed RCAS-TVA). Hyperplastic lesions in the mammary gland induced by somatic introduction of PyMT using the RCAS-TVA system display a robust DDR accompanied by increased p53 and apoptosis. This observation represents the first study, to our knowledge, to fully recapitulate DDR signaling in response to acute oncogenic stress in the in vivo mammary gland.
20–30% of all breast cancers display amplification of ErbB2, a cellular oncogene which, when activated in somatic murine mammary cells, forms sporadic tumors with a long latency. Like RCAS-PyMT, we found that p53 stabilization and apoptosis, as well as senescence, are induced by somatic activation of RCAS-ErbB2. In advanced RCAS-ErbB2-induced tumors, DDR signaling and ARF induction persist, yet p53 stabilization and apoptosis are lost. Surprisingly, attributes of senescence remain in some of the ErbB2 tumor cells. To demonstrate that the DDR is critical for oncogene-induced apoptosis and senescence, we generated RCAS-ErbB2 lesions in ATM-deficient mice. Strikingly, p53 stabilization, apoptosis, and senescence were no longer activated following ErbB2 activation in the absence of ATM signaling. These data suggest that a DDR plays a critical role in inhibiting breast carcinogenesis by inducing senescence and apoptosis, the latter, but not the former, of which is lost in progression to tumors. Furthermore, these findings indicate that therapies designed to bolster the activity of DDR signaling kinases and effectors may have a broad role in breast cancer prevention.
Citation Information: Cancer Res 2009;69(23 Suppl):B21.
Abstract B29: Inactivation of suppressor of fused alone is not sufficient to cause medulloblastoma
Authors: Satkunendran Thevagi , Ward Ryan J. , Dirks Peter B. , Hui Chi-chung 
Published: May 2012

Abstract
Hedgehog (Hh) signaling is essential for embryonic development and adult homeostasis. Aberrant pathway activity can result in various developmental disorders and tumors. The Hh receptor Patched (PTCH1) is a negative regulator of the pathway and acts as a tumor suppressor. We and others have shown that suppressor of fused (SU(FU)) and KIF7 are two major negative regulators of the pathway downstream of PTCH1.
Medulloblastoma (MB), the most common and aggressive pediatric brain tumor arising in the cerebellum, involves deregulation of Hh signaling. Similar to those observed in patients with PTCH1 mutations, Ptc1+/− mice spontaneously develop MB. In Ptc1+/− mice, the incidence of MB increases upon exposure to DNA damaging agents or a compounded loss of other tumor suppressor genes, such as p53. SU(FU) mutations have been found in MB, suggesting that SU(FU) is also a tumor suppressor in the cerebellum. However, we found that Su(fu)+/− mice do not develop any spontaneous MB, and that upon neonatal exposure to X-ray irradiation as well as a chemical carcinogen, these mice do not form any tumors. To examine the potential tumor suppressor function of Su(fu) in the brain, we performed conditional deletion of Su(fu) in neural progenitors. In mice, deletion of Su(fu) in neural progenitors using the Nestin-Cre line resulted in a disorganized cerebellum and motor defects. Unexpectedly, unlike Nestin-Cre;Ptc1f/- mice which developed MB, MB formation was not observed in Nestin-Cre;Su(fu)f/- mice. In contrast, similar to those reported previously, 100% of Su(fu)+/−;p53−/− mice developed MB between 2.5–4 months of age. Molecular analysis of primary tumor cell lines from these MBs revealed a loss of the wild type Su(fu) allele in the tumors. Together, these observations indicate that loss of Su(fu) alone is not sufficient for transformation into MB and suggest that other molecules, such as Kif7, may possess compensatory functions in the suppression of the tumor phenotype. Currently, we are examining the effects of Kif7 inactivation alone and in conjunction with Su(fu) inactivation on MB formation.
Citation Information: Cancer Res 2009;69(23 Suppl):B29.
Abstract B37: PSCA haploinsufficiency enhances prostate tumor growth in prostate-specific Pten knockout mice
Authors: Moore Miranda L. , Tang Shuai , Willingham Mark C. , Dubey Purnima 
Published: May 2012

Abstract
Prostate cancer is a heterogeneous disease, with multiple stages of cancer evident within an individual organ. Although some of the genetic changes necessary to initiate or advance prostate cancer have been identified, in order to develop effective therapies, it is critical to understand the different means by which this disease develops and progresses. Prostate Stem Cell Antigen (PSCA) is a GPI-anchored cell surface protein that is expressed in the normal epithelial cells of a restricted set of organs, including prostate, bladder, stomach, kidney and pancreas. Over-expression of PSCA is found in all stages of prostate cancer, from PIN to metastasis.
We are investigating the biological function of PSCA in prostate tumorigenesis. We recently reported that deletion of PSCA increases metastasis of TRAMP-induced prostate tumors in mice, suggesting that PSCA may function as a tumor suppressor. To determine the effect of modulating PSCA dosage in the context of another oncogenic signal implicated in human prostate cancer development, we crossed PSCA knockout mice to prostate-specific Pten knockout mice, and analyzed the animals at 30 weeks of age. Pten −/−;PSCA +/− mice developed significantly larger prostate tumors than Pten −/− mice that are wild-type for PSCA. These results also suggest that PSCA may function as a tumor suppressor. In contrast, mice with deletion of both copies of the PSCA gene (Pten −/−; PSCA −/− mice) developed tumors similar in size to Pten −/−;PSCA +/+ animals, consistent with the possibility that PSCA function may contribute to the early stages of cancer development.
Together, our results suggest that modulation of PSCA gene dosage affects cancer initiation and progression, indicating a putative dual role for PSCA in epithelial cancer. Our current experiments are designed to determine the molecular mechanism of PSCA function.
Citation Information: Cancer Res 2009;69(23 Suppl):B37.
Abstract B53: Post-translational modification of p53 by HDAC inhibitors leads to selective assembly of transcriptional complexes at the p21 locus
Authors: Keith James , Roy Somdutta , Tenniswood Martin 
Published: May 2012

Abstract
CG-1521 is a novel histone deacetylase (HDAC) inhibitor that stabilizes the acetylation of p53 at lysine 373, triggering G2/M phase arrest and apoptosis in LNCaP cells. This is in contrast to the well known HDAC inhibitor trichostatin A (TSA) which stabilizes the acetylation of lysine 382 on p53 and triggers G1/S phase arrest and senesence. The known p53 target gene, p21, contains two p53 response elements (RE) and 6 Sp1 binding sites in its promoter. Previous work in LNCaP cells indicates acetylated p53 isoform-modulated assembly of an active or inactive transcriptional complex at these p53REs in response to CG-1521 or TSA, respectively. Consistent with this finding, p21 mRNA levels were increased only upon treatment with CG-1521. Treatment with either HDAC inhibitor led to the upregulation of p21 protein levels, with a difference in the speed and duration of this increase. A second protein, p21B, coded within the exons and introns of the classical p21 protein, has been implicated in the apoptotic response, should the cellular DNA repair machinery fail to resolve a genomic insult. p21B appears to be controlled by a p53RE within the first intron of p21. This RE exhibits the same qualitative loading characteristics of the classical p21 p53RE in response to cellular stress and the acetylation state of p53, yet is temporally expressed later than p21. Using chromatin immunoprecipitation assays at narrow timepoints, we have determined the temporal loading characteristics of this region upon treatment with the HDAC inhibitors CG-1521 and TSA. Our results demonstrate a clear difference in the components of the basal transcriptional complex depending on the HDAC-stabilized acetylation state of p53. This indicates the acetylation state of the p53 protein is an important regulator of the cellular response to stress and suggests HDAC inhibitors may have an important role as cancer therapeutics beyond their traditional role in histone modification.
Citation Information: Cancer Res 2009;69(23 Suppl):B53.
Abstract B58: Neurofibromin: A required GAP in lens development
Authors: Carbe Christian J. , Zhang Xin 
Published: May 2012

Abstract
Human neurofibromatosis 1 (NF1) is an autosomal dominant genetic disease characterized by multiple discrete dermal neurofibromas as well as optic and other central nervous system gliomas. NF1 patients have a high incidence of additional clinical symptoms including cafe-au-lait spots, hamartomas in the iris (Lisch nodules), macrocephaly, short stature, seizures, and learning disabilities. Neurofibromin, the protein product of the Nf1 gene has been shown to function as a Ras-GTPase activating protein (GAP), thus making it a tumor suppressor protein. Neurofibromin may also regulate adenyl cyclase activity and intracellular cyclic-AMP generation. Here, we show that neurofibromin, as a functional GAP protein, is required for normal murine lens induction. Utilizing a previously developed strain of Nf1-deficient mice, we demonstrate that Nf1−/− embryos exhibit severe lens hypoplasia, and in some cases, anophthalmia. By analyzing RNA (Ras target gene expression) as well as target protein expression patterns (Phopho-ERK), we demonstrate that MAPK signaling is indeed upregulated in the lens region of the developing Nf1−/− embryo at E9, but down regulated after E10. Interestingly we observe a simultaneous down-regulation of transcription factors Pax6, and Sox2, both necessary for normal lens development after E10, which, is the same time we begin to observe poor or absent lens induction. However, the smaller deformed lenses that do form in the Nf1 mutants still express key lens marker proteins (alpha-A crystalline, Prox1), indicating that lens cell differentiation appears to occur normally after lens induction. Cell proliferation studies (BrdU immunohistochemistry) at both E9 and E10 revealed E9 Nf1−/− lens cell proliferation to be normal, however, significantly decreased at E10. In addition, TUNNEL staining performed at both E9 and E10 indicate normal apoptosis in the developing Nf1−/− lens. To test our hypothesis that increased MAPK signaling is the mechanistic cause of the hypoplastic lens, we initiated rescue experiments by injecting E10-pregnant females with MEK inhibitor UO126 and then analyzed the lenses of E12-harvested embryos. Our results do show that attenuation of the MAPK pathway does indeed rescue the mutant lens phenotype, thus confirming our assertion that neurofibromin is an essential GAP protein required for normal lens development.
Citation Information: Cancer Res 2009;69(23 Suppl):B58.
Abstract B64: Telomeric DNA sequence determines the mechanism of dysfunctional telomere fusion in human cancer cells
Authors: Stohr Bradley A. , Xu Lifeng , Blackburn Elizabeth H. 
Published: May 2012

Abstract
Cancer cells rely on the ribonucleoprotein enzyme telomerase to maintain their telomeres, which consist of tandem DNA repeats bound to protective protein factors collectively termed shelterin. Experimentally-induced telomere dysfunction in cancer cells, either through critical telomere shortening or disruption of shelterin binding, typically leads to telomere fusions, ultimately resulting in genome instability and cell death. For reasons that are not well understood, the mechanism of telomere fusion varies depending on the cause of telomere dysfunction. We have investigated telomere fusions caused by overexpression of mutant telomerases that add mutated telomeric repeats, thereby disrupting shelterin binding and inhibiting cancer cell proliferation. We previously showed that the effect of one such telomerase in human cancer cells is ATM dependent (Stohr BA and Blackburn EH, Cancer Research 68:5309–5317, 2008). Here, we have tested additional mutant telomerases that add either palindromic or non-palindromic telomeric repeats. We show that while all mutant telomeric sequences tested induce heterodicentric chromosome fusions, only palindromic telomeric repeats induce ATM-independent sister chromatid and isodicentric chromosome fusions in human cancer cells. Thus, the telomeric sequence itself influences the fate of telomeres that have become dysfunctional. These results implicate DNA strand annealing in an alternative telomere fusion pathway in human cells. The need to avoid genome instability caused by such fusions is one explanation for the characteristic lack of self-complementarity in naturally-occurring telomeric sequences. Finally, our results have significant implications for the translational application of mutant telomerases as a cancer therapeutic strategy.
Citation Information: Cancer Res 2009;69(23 Suppl):B64.
Abstract B70: Conexic: A Bayesian framework to detect drivers and their function uncovers an endosomal signature in melanoma
Authors: Akavia Uri-David , Litvin Oren , Kim Jessica , Mozes Eyal , Kotliar Dylan , Tzur Yossi , Garraway Levi , Pe'er Dana 
Published: May 2012

Abstract
Genomics is revolutionizing our understanding of cancer biology. Tumor samples assayed for comprehensive chromosomal and gene expression data are accumulating at a staggering rate. A major challenge involves the development of analysis methods to uncover biological insights from these data, including the identification of the key mutations that drive cancer and how these events alter cellular regulation.
We have developed Conexic, a novel computational framework to integrate chromosomal copy number and gene expression data to detect genetic alterations in tumors that drive proliferation, and to model how these alterations perturb normal cell growth/survival. The underlying assumption to our approach is that significantly recurring copy number change, coinciding with its ability to predict the expression patterns varying across tumors, strengthens the evidence of a gene's causative role in cancer. This method not only pinpoints specific regulators within an a large region of copy number variation, but can shed light on the way in which gene regulation is altered
We applyed our Conexic framework to a melanoma dataset (Lin et al, Cancer Research, 2007) comprising 65 paired measurements of gene expression and copy number, with interesting results. Our analysis correctly identified many known ‘driver’ events, while also connecting these to many of their known targets (e.g. MITF). Our global integrative analysis reveals insight into how the drivers alter transcriptional programs. An interesting recurring characteristic is that there are a number of different ways by which drivers can be altered; e.g., the expression of a driver may be altered through copy number variation or other mechanisms, but its influence downstream remains the same.
In addition to confirming the role of known drivers in melanoma, our analysis suggests a number of novel drivers. Most strikingly, these point to a major role in regulation of protein trafficking and endosome biology in this malignancy. These results have linked endosomal processing and sorting to adhesion and survival. Preliminary experimental validation supports three novel drivers including TBC1D16, RAB7A and RAB27A. Together, these results affirm the potential of Conexic to elaborate novel driver modules with biological and possibly therapeutic importance in melanoma and other cancers.
Citation Information: Cancer Res 2009;69(23 Suppl):B70.
Abstract B71: A systems biology approach to study Ewing's sarcoma
Authors: Surdez Didier , Stoll Gautier , Tirode Franck , Laud Karine , Zinovyev Andrei , Barillot Emmanuel , Delattre Olivier 
Published: May 2012

Abstract
Ewing's sarcoma is the second most frequent pediatric bone tumor. It is characterized in 85% of cases by a chromosomal translocation which leads to the expression of a chimeric transcription factor: EWS-FLI1. This oncogene is transforming in various cell and animal models. Although important EWS-FLI1 transcription targets and altered pathways have been described, a comprehensive understanding of the disease remains to be achieved. For this purpose, a systems biology approach was used. In this project, gene profiling of (1) primary tumors and (2) of EWS-FLI1-inducible cell models were performed. Based on these experimental data and on literature knowledge, we constructed an annotated influence network of EWS-FLI1 effects that was validated using small scale silencing/qPCR experiments and home-made software. In a second step, in order to better understand the global impact of EWS-FLI1 in Ewing sarcoma context, EWS-FLI1 ChIP-seq experiments were performed. These results were combined to the gene expression profile data using rational approaches and/or PCA based analyses. This resulted in a genome wide analysis in which the genes were ranked upon their implication/significance in Ewing sarcoma. In the future, we intend to integrate these results to an extended version of our annotated influence network and confront high-throughput experimental results (siRNA screen) with predictive computational models of this network. This should allow identifying novel crucial genes/pathways in Ewing's sarcoma.
Citation Information: Cancer Res 2009;69(23 Suppl):B71.
Abstract B75: TWISTing Stemness, Inflammation, and Proliferation of Epithelial Ovarian Cancer Cells through MIR199A2/214
Authors: Yin Gang , Chen Rui , Fu Han-Hsuan , Alvero Ayesha , Glackin Carlotta , Mor Gil 
Published: May 2012

Abstract
Introduction: Twist1, a basic helix-loop-helix (bHLH) transcription factor, has an important role in tumor biology by regulating epithelial-mesenchymal transition. It also functions as a transcription repressor in NFκB-dependent cytokine expression. Recently, we reported the identification and characterization of epithelial ovarian cancer (EOC) cells with stem-like properties (Type I EOC cells). At the microRNA level, Type I EOC cells are characterized by low levels of hsa-miR-199a2 and hsa-miR-214. We also demonstrated the capacity of Type I EOC cells to differentiate into mature ovarian cancer cells (Type II EOC cells), which has lost stemness potential and express high levels of both hsa-miR-199a2 and hsa-miR-214. We also showed previously that hsa-miR-199a2 is able to regulate the levels of IKKβ and therefore have a direct effect on the NFκB pathway. Still, another group reported the regulatory control of hsa-miR-214 on the Akt pathway. In this study, we show that Twist1 is able to regulate the miR-199a2/214 cluster in EOC cells and can therefore control both NFκB and Akt pathways.
Methods: 5′-RACE and 3′-RACE was used to clone the full length pre-miR-199a gene. Real-time PCR was used to determine the levels of Twist1 and miR-199a2/214. Twist1 was knocked-down in Type II EOC cells using siRNA. The effect of Twist1 knockdown on levels of IKKβ was determined by Western blot analysis. Cytokines were quantified using Luminex technology.
Results: Characterization of full length of pre-miR-199a2 transcript reveals that the MIR199A2 gene contains a human microRNA cluster, miR-199a2/214, and pre-miR-199a2 within the human Dnm3os gene (NCBI GeneID 474332). PCR analysis showed low levels of Twist1 and miR-199a2/214 in Type I EOC cells but high levels of expression in Type II EOC cells. Knockdown of Twist1 in Type II cells induce a significant decrease in the levels both hsa-miR-199a2 and hsa-miR-214, and significant increase in IKKβ expression. Ectopic expression of hsa-miR-199a2 partially reverse the effect of Twist-1 knockdown on the levels of IKKβ. The combination of knockdown Twist1 and TNFα stimulation in Type II EOC cells significantly increase Rantes, an NFκB-dependent cytokine.
Conclusion: We demonstrate for the first time that Twist1 plays a feedback role for the NFkB pathway by repressing IKKβ expression through hsa-miR-199a2. Twist1 inhibition of IKKβ expression through regulating hsa-miR-199a2, represents a novel negative feedback loop for the NFκB pathway. The demonstration that Twist1 can regulate the miR-199a2/214 cluster and therefore both the IKKβ and Akt survival pathways, suggests the potential role of Twist1 in EOC differentiation. Furthermore it opens the opportunity to develop new approaches for targeting the ovarian cancer stem cells.
Citation Information: Cancer Res 2009;69(23 Suppl):B75.
Abstract B9: Arm1: A glutamate methyltransferase capable of methyl esterifying PCNA
Authors: Hoelz Derek J. , Albert Alexandra , Dobrolecki Lacey , Arnold Randy , Novotny Milos , Schnaper Lauren , Hickey Robert , Malkas Linda 
Published: May 2012

Abstract
Recently we reported on a novel post-translational modification (PTM) present on proliferating cell nuclear antigen (PCNA). This PTM (methyl esterification) was found acidic residues, primarily glutamic acids. Interestingly, methyl esterification of glutamic acids in proteins has only been observed in bacteria where a specialized glutamate carboxyl O-methyltransferase, CheR, has been shown to methyl esterify specific glutamic acid residues of receptors during chemotaxis signaling. In eukaryotic cells, however, only three carboxyl O-methyltransferases are known to exist and none of them have specificity for glutamic acid residues. Here we describe the isolation and identification of a protein encoded by an unknown open reading frame and expressed in human cells that may represent the first eukaryotic glutamate carboxyl O-methyltransferase, which can modify PCNA. Sequence alignment of this protein with other protein carboxyl O-methyltransferases has demonstrated the existence of multiple consensus and conserved regions, and secondary structural predictions confirm a potential to form a SAM-dependent methyltransferase fold in its C-terminus. We therefore named this protein acidic residue methyltransferase 1 (Arm1). The biological significance of this discovery and its potential role(s) in DNA replication and repair will be discussed.
Citation Information: Cancer Res 2009;69(23 Suppl):B9.