bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 5059: Detection of K-RAS mutation in clinical samples by one-step PNA-mediated real-time PCR clamping techniques
Authors: Cho Minhye , Choi Jae-Jin , Park Heekyung 
Published: February 2011

Abstract
Mutations in the K-RAS oncogene are frequently found in human cancers. K-RAS mutations may indicate prognosis and drug response, and many new cancer therapies are being targeted to the K-RAS pathway. Many researchers suggest that in colon cancer patients the K-RAS mutation status is strong predictor of resistance to therapy with tyrosine kinase inhibitors such as Erbitux® (cetuximab/ Imclone system Inc) or Vectibix® (panitumumab/ Amgen Inc). Therefore, it is important that detection of K-RAS mutations is fast and simple with high accuracy and high sensitivity for predict drug response and prognosis.
To detect a minority of mutant K-RAS among abundant wild-type alleles, we developed a high sensitivity and simple method for detection of K-RAS mutations using PNA-mediated real-time PCR clamping. PNA mediated real-time PCR clamping relies on the following two unique properties of PNA probes. 1) PNA-DNA duplexes generally have greater thermal stability than the corresponding DNA-DNA duplex and 2) PNA oligomers are not recognized by DNA polymerases and consequently can serve as sequence selective clamp during PCR amplification.
One-step PNA-mediated real-time PCR clamping method was optimized for detection of K-RAS mutations in exon 12 and 13 with high sensitivity. This method was simple and correct with detection limit approximately 0.1% mutant alleles using 10ng to 50ng of normal DNA as the template. The turnaround time for performing this assay was only 2.5hrs.
K-RAS mutations were detected in 24.4% (22/90) of clinical samples, of which 18 had mutations in codon 12 and 4 had these in codon 13. To confirm these results, same clinical samples were analyzed with sequencing assay. The concordant results were obtained from 88 (98%) of the 90 clinical samples by the two assays. The PNA-mediated real-time PCR clamping is a rapid and reliable tool for K-RAS mutation detection and allowed a minority of mutant in clinical field.
Keywords: K-RAS, Mutation, PNA, cancer, PCR clamping
This work was supported be the Small and Medium Business Administration funded by the Korean Government. (S1060400)
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5059.
Abstract 506: A time-dependent genome-wide gene interaction signature in U251 human glioma cell line exposed to ionizing radiation
Authors: Zach Leor , Hakim Ofir , Sung Myong Hee , Hager Gordon , Kevin Camphausen 
Published: February 2011

Abstract
Background: The effects of ionizing radiation on DNA integrity and functionality are well studied and reported. However, little is known about how irradiation affects large-scale nuclear architecture. We sought to investigate the latter using Chromosome Conformation Capture on Chip (4C) which assesses the spatial genomic organization around a locus of interest. Methods: U251 glioma cells were grown in standard media to 70% confluence, irradiated (6Gy) and harvested 6 and 24 hours after irradiation. We obtained all genomic loci in close physical proximity to an irradiation induced gene Alf1 on chromosome 6 as bait. 4C was performed in duplicate samples on control or irradiated cells, using custom NimbleGen microarrays that contained probes for all potential partner sites in the genome. Results: Alf1 locus was found to be engaged in multiple intra-chromosomal interactions with other regions in chromosome 6, and inter-chromosomal interactions with multiple areas in chromosomes 1,2,5,7,10 15 and 17 prior to irradiation. Irradiation induced changes in the Alf1 spatial environment as many of the contacts were lost, while additional interactions were induced. A partial recovery to the baseline nuclear architecture was evident 24 hrs after irradiation. Conclusions: Our preliminary results are intriguing and might suggest a new tool to investigate the effects of ionizing irradiation on nuclear high-order structure. A specific, time dependent post irradiation DNA architecture changes in tumor cells may correlate to the (and reproducible) levels of sensitivity to ionizing irradiation of different areas of the DNA in a specific tumor cell population.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 506.
Abstract 5063: Signatures of Ral GTPase status define key clinicopathologic characteristics and outcomes in cancer
Authors: Smith Steven C. , Baras Alexander S. , Wang Hong , Owens Charles R. , Theodorescu Dan 
Published: February 2011

Abstract
Ral GTPases, which include RalA and RalB, mediate essential phenotypes in model cancer systems; however, demonstration of the clinical relevance of these molecules has been lacking. To address this concern, we develop two types of gene expression signatures as surrogates for Ral GTPase status in tumors and characterize their nosologic and prognostic performance across several epithelial malignancies. Given Ral's well characterized role in regulating a variety of transcriptional pathways including AP1, NFkB, STAT3B, forkhead family members, and RREB1, the first type of signature is related to transcription downstream of RalA and RalB and was derived empirically from expression profiling of cells depleted of these molecules. This signature was then applied to human tumor gene expression data by using a nearest neighbor algorithm for classification. Consistent with prior findings of a role for these molecules in model surrogates of cancer progression(1,2), presence of the Ral transcriptional signature characterized the muscle invasive status of human bladder cancer (P&lt;0.001), including prediction of subsequent development of invasion in non-invasive tumors (P&lt;0.01). In prostate cancer, the signature characterized androgen independent status, and estrogen receptor status in human breast cancer, both datasets P&lt;0.05. Supportive of a recent report of tumor suppressor function of Ral in a model of squamous cell cancer (3), the signature was inversely associated with stage in this tumor type.
Secondly, we have assayed constitutively-active RalA and RalB mutants, finding that either induces accelerated experimental metastasis of UMUC3 bladder cancer cells in mice (logrank P=0.01), similar to results for other tumor types (4). This made us question whether signatures of metastasis from tumor profiling could be associated with differential Ral activation. We assayed the activation of RalA and RalB across 40 cell lines, then mapped individual tumor expression of metastatic genes to these cell lines in silico. Using this methodology to compare tumors to cell lines of known Ral activation, we found association of higher Ral activation with nodal metastasis in bladder cancer and with visceral metastasis in breast cancer, both P&lt;0.05. Taken together, these findings begin to make the as yet missing clinical case for the Ral pathway in human tumors and call for aggressive investigation of therapies to interrupt this pathway.
(1) Oxford, Cancer Res, 2005
(2) Lim, Curr Biol, 2006
(3) Sowalsky, Oncogene, 2009
(4) Yin, Mol Cell Biol, 2007
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5063.
Abstract 5068: Identification of RASSF1A as a novel RhoA antagonist: direct interaction with and Smurf1-mediated ubiquitination of RhoA
Authors: Ryu Byung-Kyu , Lee Min-Goo , Kang Min-Ju , Ha Tae-Kyu , Han Jikhyon , Her Nam-Gu , Chung Seong-In , Chi Sung-Gil 
Published: February 2011

Abstract
RASSF1A is a tumor suppressor which plays a critical role in the regulation of various aspects of cellular functions, including cell proliferation, apoptosis, and motility. RASSF1A is frequently inactivated in various types of human cancers by transcriptional silencing of the gene due to aberrant promoter hypermethylation. However, molecular mechanisms underlying its tumor suppressive functions were largely undefined. We characterized RASSF1A regulation of a small GTPase RhoA and its implication in tumor cell migration and invasion. Effect of RASSF1A expression on RhoA activity was examined by immunoblot, immunopricipitation, and ubiquitinylation assays, and RASSF1A modulation of RhoA-mediated cell migration and invasion was determined using wound healing and in vitro invasion assay. We identified that RASSF1A inhibits serum- or LPA-induced RhoA activation in both cancer cells and noncancerous cells. SiRNA-mediated knockdown of RASSF1A increases RhoA activity and RhoA-mediated tumor cell migration. RASSF1A promotes the protesomal degradation of GTP-bound RhoA via Smurf1-mediated ubiquitinylation, but does not affect the activity and stability of Rac1 and CDC42. Immunofluoroscence and immunopricipitation assays revealed that RASSF1A colocalizes and interacts with RhoA and Smurf1. The N-terminal region of RASSF1A interacts with Smurf1, and its C-terminal residues (amino acids 266-272) are critical for the interaction with RhoA. The mutant RASSF1A (delNC-RASSF1A) having a sequence alteration in the Smurf1 and RhoA binding region fails to inhibit the RhoA-mediated tumor cell migration and invasion. Consistent with theses results, loss or abnormal reduction of RASSF1A expression exhibits a tight correlation with RhoA activation in both cancer cell lines and primary tumors of various tissues origins. Our study demonstrates first that RASSF1A regulates cell motility through the proteosomal degradation of activated RhoA through Smurf1-mediated ubiquitinylation, indicating that genetic and epigenetic inactivation of RASSF1A during tumorigenic process increases the invasive and metastatic potential of tumor cells by deregulation of RhoA.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5068.
Abstract 5069: c-Abl contributes to Mdm2-Mdmx complex formation protecting p53 levels
Authors: Waning David L. , Mayo Lindsey D. 
Published: February 2011

Abstract
This study was designed to better understand the signaling events through c-Abl kinase that impact p53 activity. The p53 tumor suppressor protein is a key protein in maintaining the integrity of the genome by inducing either cell cycle arrest or apoptosis following cellular stress signals. Two human family members, Mdm2 and Mdmx, are primarily responsible for inactivating transcription initiation of p53 or destabilizing p53 through ubiquitination. In response to genotoxic stress, post-translational modifications to Mdm2 and Mdmx relieve inhibition on p53, which is in part mediated through the c-Abl kinase. c-Abl is necessary for maintaining p53 expression levels and for maximal accumulation of p53 following DNA damage. While p53 is not a direct substrate of c-Abl there are c-Abl phosphorylation sites present in Mdm2 and Mdmx. Considering that c-Abl regulates both Mdm2 and Mdmx, we designed this study to understand the role of c-Abl phosphorylation of Mdm2 in protecting p53 activity. We hypothesized that protection of p53 would be linked to Mdm2-Mdmx complex formation and modulated by c-Abl phosphorylation. Here we present a mechanism of p53 stabilization whereby c-Abl promotes Mdm2-Mdmx heterodimer complex formation. For this study we used multiple complementary approaches including: recombinant in vitro protein assays, therapeutic drug treatments of cells and targeted mutagenesis of Mdm2 phosphorylation sites to show the role of c-Abl in protecting p53. Additionally, blocking c-Abl phosphorylation has therapeutic implications in treatment of disease through modulation of p53 activity. There are several small molecule inhibitors that affect c-Abl activity, such as imatinib, and a better understanding of the mechanistic role of c-Abl in the stoichiometric balance between Mdm2 and Mdmx may lead to better approaches for engaging p53 activity. This could lead to improvements in current disease treatment and the development of novel therapeutics for cancers harboring wild-type p53.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5069.
Abstract 507: Elevated manganese superoxide dismutase (SOD2) activity as a mechanism for the low dose dadiation- and thiol-induced adaptive responses in human RKO36 colon carcinoma cells and BFS2C mouse fibrosarcoma cells
Authors: Murley Jeffrey S. , Baker Kenneth L. , Kataoka Yasushi , Weichselbaum Ralph R. , Grdina David J. 
Published: February 2011

Abstract
Exposure of cells to low non-lethal doses of ionizing radiation (≤ 10 cGy) or WR1065, the active free thiol form of amifostine, can induce pro-survival pathways that result in protection against the damaging effects of a 2 Gy dose of ionizing radiation. One such signaling pathway involves the elevation of active manganese superoxide dismutase (SOD2). SOD2 is a mitochondrial matrix protein that serves as the primary mitochondrial defense against superoxide formation. Its primary function is to facilitate the dismutation of two molecules of superoxide anion (O2−) produced by normal respiratory processes or following exposure to ionizing radiation into water and hydrogen peroxide. To characterize the role of SOD2 in the radiation- and thiol-induced adaptive responses, RKO36 human colon carcinoma cells and BFS2C mouse fibrosarcoma cells were exposed to 10 cGy x-rays and 40 μM or 4 mM WR1065 and SOD2 activity measured 24 h later. Significant increases in SOD2 activity in RKO36 cells (3.7-fold, P &lt; 0.001) and BFS2C cells (3.0-fold, P = 0.005) were observed 24 h after exposure to 10 cGy. SOD2 activity was also observed to be significantly elevated in RKO36 cells (3.5-fold, P = 0.014 and 3.4-fold, P = 0.017) and BFS2C cells (3.7-fold, P = 0.007 and 2.5 fold, P = 0.021) 24 h after treatment with 40 μM or 4 mM WR1065, respectively. The protective effect of the low dose radiation- and thiol-induced elevation in active SOD2 was examined using the endpoint of micronuclei formation as a measure of chromosomal damage. Exposure of RKO36 and BFS2C cells to 2 Gy resulted in a significant increase in the mean number of micronuclei observed relative to unirradiated control cells (8.8 versus 2.2, P &lt; 0.001; 5.4 versus 2.1, P &lt; 0.001, respectively). The frequency of micronuclei formation was significantly reduced in both RKO36 cells (P = 0.003) and BFS2C cells (P = 0.011) exposed to 10 cGy 24 h prior to the 2 Gy dose. A significant reduction in micronuclei formation was also observed in RKO36 and BFS2C cells treated with 40 μM or 4 mM WR1065 30 min or 24 h prior to irradiation with 2 Gy. Treatment of both cell lines with SOD2 siRNA reduced SOD2 activity relative to mock-transfected control cells which resulted in the abrogation of both the radiation- and thiol-induced protective effect. This work was supported by NIH/NCI grant R01 CA132998 and DOE grant DE- PS02-08ER08-21 (D.J.G.).
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 507.
Abstract 5070: Identification of DKK2 as a candidate gene that facilitates tumor reoccurrence upon MYC inactivation
Authors: Adam Stacey J. , Xu Liwen , Karlsson Asa , Felsher Dean W. 
Published: February 2011

Abstract
The MYC oncogene is prevalently activated in human hematopoietic cancers, especially T-cell acute lymphoblastic leukemia (T-ALL) and Burkitt's lymphoma. Utilizing the Tet-system to generate a conditional model of MYC-induced T-ALL, our laboratory has demonstrated that MYC inactivation induces sustained tumor regression. However, after prolonged MYC inactivation some tumors eventually escape MYC dependence and reoccur. Our results support the hypothesis that tumors escape complete dependence on MYC by acquiring additional genetic or epigenetic changes, leading to altered gene function that may substitute totally or partially for MYC. Specifically, using Spectral Karyotypic Analysis (SKY) and array Comparative Genomic Hybridization (aCGH) we have obtained evidence that the Wnt/ β-catenin related gene, DKK2, may play a role in the mechanism by which tumors escape dependence upon MYC. We demonstrate DKK2 facilitates the ability of MYC-driven lymphomas to reoccur even in the presence of sustained oncogene inactivation. We have evidence that cellular context may play a pivotal role in DKK2's ability to aid tumor reoccurrence. Our data also suggest a mechanism by which DKK2 functions, alone or in conjunction with other Wnt/β-catenin pathway members, to maintain tumorigenesis or facilitate tumor reoccurrence in murine and human MYC-driven tumors in the presence of sustained MYC inactivation. Discovering that DKK2 overexpression may aid in lymphoma reoccurrence is a highly novel finding as DKK2 has never been implicated as an oncogene in lymphoma. Results presented here provide critical new insights into the mechanism by which MYC-driven cancers may obtain chemotherapeutic resistance and reoccur even in the presence of sustained drug therapy.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5070.
Abstract 5071: Defining the role of canonical MAPK signaling in glioma initiation and maintenance
Authors: Lastwika Kristin J. , Robinson James P. , VanBrocklin Mathew W. , Brandner Sebastian , Homen Sheri L. 
Published: February 2011

Abstract
Mutations in receptor tyrosine kinase (RTK) growth factor receptors e.g., EGFR, PDGFR, MET and ERBB2 which result in constitutive downstream signaling of the canonical mitogen activated protein kinase (MAPK) (e.g., RAS/RAF/MEK/ERK) and phosphatidylinositol 3-kinase (PI3K)/AKT pathways, are found in almost all World Health Organization (WHO) grade II, III, and IV astrocytomas. KRAS, BRAF and CRAF mutations occur in approximately 6%, 72% and 2% of low grade gliomas (WHO Grade I), respectively. A recent study also found a 5-fold increase in RAF serine/threonine kinase activity in a significant series of grade III and IV gliomas, coupled with a 12-fold increase in BRAF and a 2-fold increase in CRAF protein levels. By using an established glioma mouse model, it has been demonstrated that KRas, CRAF or BRAF expression in nestin expressing neural progenitor cells, combined with either Akt activation or Ink4a/Arf loss, leads to the development of high grade gliomas. Together, these data clearly demonstrate the importance of MAPK signaling in glioma development. However, KRAS, BRAF and CRAF are all differently regulated. To further validate a role for canonical MAPK signaling in glioma formation, we have evaluated the effect of constitutive MEK1 activity in glioma formation in vitro and in vivo. While expression of activated MEK1 alone is not sufficient for tumorigenesis, the combination of activated MEK1 and Akt, or MEK1 with Ink4a/Arf loss leads to glioma formation. To assess the efficacy of targeting MAPK signaling in gliomas, we treated a large panel human GBM cell lines with the MEK inhibitor PD0325901 alone and in combination with the PI3K/mTOR inhibitor BEZ235. Cell lines with the highest levels of ERK activation were the most sensitive to MEK inhibition while those with the highest levels of AKT activation were protected from apoptosis following MAPK inhibition. Treatment with BEZ235, in combination with PD0325901, caused significantly higher levels of apoptosis in the glioma cell lines. Importantly, neither treatment induced apoptosis in normal human astrocytes. Our studies demonstrate that activation and signaling through the MAPK pathway following Ink4a/Arf loss or Akt activation can give rise to high grade gliomas; moreover MAPK inhibition, when combined with PI3K/mTOR inhibition may prove to be an effective treatment for gliomas.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5071.
Abstract 5073: SIAH2 antagonizes the growth-inhibitory activity of the TGFβ signaling pathway and enhances the growth-promoting activity of the RAS signaling pathway during the genesis and progression of human cancer
Authors: Liao Yang , Edens Maryanne , Leof Edward B. , Tang Amy H. 
Published: February 2011

Abstract
A better understanding of the antagonistic interaction and cross-talk between the pivotal oncogenic and tumor suppressor signaling pathways, and the concerted cancer signaling networks that control tumorigenesis and metastasis should give rise to novel therapeutic interventions. Hyperactivated ERBB/RAS is known to drive neoplastic transformation, tumorigenesis and metastasis in a large percentage of human cancers, and thus finding novel measures to countervail activated EGFR/HER2/RAS signals to reverse tumorigenesis and metastasis remains an important goal in cancer biology. Instead of targeting an upstream signaling component, we targeted the most downstream signaling module in the ERBB/RAS pathway, the SIAH-dependent proteolytic machinery. SIAHs are evolutionarily conserved RING E3 ligases that are the critical downstream “gatekeeper” signaling modules in the RAS signal transduction pathway. We show that human SIAH E3 ligase is upregulated in proliferating tumor cells in human tumor specimens, and that proper SIAH function is required for RAS signal transduction. By inhibiting SIAH2 E3 ligase, we have blocked both tumorigenesis and metastasis in eleven of the most aggressive human cancer cell lines known in athymic nude mice. Our observations highlight the important roles that SIAH2 plays in RAS-dependent tumorigenesis and metastasis in human cancer. In this study, we aim to identify the molecular mechanism underlying SIAH2 deficiency-mediated growth inhibition in human cancer cells. We have found that SMAD2/3/4 - the essential downstream mediators of TGFβ signaling, are novel SIAH2 substrates in that SIAH2 physically interacts with, ubiquitinates and degrades SMAD2/3/4 (not SMAD1). The identification of SIAH2-mediated SMAD2/3/4 modulation may provide an additional molecular mechanism to explain the well documented, but less understood RAS-TGFβ antagonism described in normal development, tumorigenesis and metastasis. We propose that the tumor promoting activity of SIAH2 may be mediated through the degradation of SMAD2/3/4 proteins which enhancing the growth-promoting activity of the RAS pathway while suppressing the growth inhibitory action of the TGFβ pathway. Since the substrate specificity of ubiquitin-mediated proteolysis is primarily determined by the E3 ligase, our results provide new insights into the role of altered proteolysis in mediating the RAS-TGFβ antagonism and cross-talk observed in the genesis and progression of human cancers.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5073.