bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 2707: Quantitative analysis of the role of androgen receptor in radiation treatment for prostate cancer
Authors: Qian Mengdi , Almasan Alexandru , Gurkan-Cavusoglu Evren 
Published: July 2016

Abstract
The purpose of this study is to quantitatively investigate the mechanism of androgen receptor (AR) and non-homologous end joining (NHEJ) interaction after and ionizing radiation (IR) and androgen deprivation therapy (ADT) treatment. In most clinical treatment approaches, a combination of ADT and IR is used in order to improve prostate patients’ overall survival probability. It is found that AR interacts with NHEJ pathway, a major double strand break (DSB) repair pathway. We have developed a mathematical model of the NHEJ pathway that is composed of a series of ordinary differential equations. The kinetic rate constants constitute the unknown parameters of the model and we have estimated these parameters using least square estimation. The data sets used in the parameter estimation were obtained from the literature and they were from both in vitro experiments as well as clinical data from prostate cancer patients. Both sets of data demonstrated the effects of AR on DSB repair by NHEJ. The in vitro data suggest that AR enhances DSB repair by inducing expression/activity of DNA-PKcs, which is a key protein in NHEJ. The clinical data show that the effect is through the first NHEJ protein complex that is recruited to DSB, Ku70/80. We have developed the models for IR treatment alone or in combination with ADT to determine which of these mechanisms can explain the behavior in both data sets simultaneously. We have carried out sensitivity analysis and identifiability tests on all the parameters from both models in order to determine the parameters that are reliably estimated. We have shown that when the rate constant for the initiation protein Ku70/80 is decreased to half in the IR+ADT case compared to the IR only case, the model outputs captured the observations in both experimental and clinical data. The rate constant for Ku70/80 is proved to be both sensitive and identifiable, indicating that the two-fold difference in the rate constants of IR only and IR+ADT cases is biologically relevant. Therefore, we conclude that when ADT is applied, AR significantly slows down the kinetic activity of Ku70/80, thus the DSB repair by NHEJ. The suppression of AR activity through ADT has the potential to enhance the IR treatment outcomes for the prostate cancer patients that are resistant to IR-only treatment.
Citation Format: Mengdi Qian, Alexandru Almasan, Evren Gurkan-Cavusoglu. Quantitative analysis of the role of androgen receptor in radiation treatment for prostate cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2707.
Abstract 2725: Probing mitotic functions of BUB1 kinase using the small molecule inhibitors BAY-320 and BAY-524
Authors: Baron Anna P. , von Schubert Conrad , Cubizolles Fabien , Siemeister Gerhard , Hitchcock Marion , Mengel Anne , Schröder Jens , Fernández-Montalván Amaury , Lange Martin , von Nussbaum Franz , Mumberg Dominik , Nigg Erich 
Published: July 2016

Abstract
The maintenance of correct chromosome number (euploidy) during cell division is ensured by a highly conserved surveillance mechanism termed ‘spindle assembly checkpoint’ which safeguards correct chromosome segregation by delaying anaphase onset until all chromosomes are properly bi-oriented on the spindle apparatus. The mitotic kinase BUB1 (budding uninhibited by benzimidazoles 1) was reported to contribute to both chromosome congression and checkpoint function, yet the role of BUB1 catalytic activity in these processes remains a matter of debate.
To differentiate between catalytic and non-catalytic functions of BUB1 we compared phenotypes provoked by BUB1 protein depletion with specific BUB1 kinase inhibition using two novel small molecule inhibitors of BUB1, termed BAY-320 and BAY-524.
BAY-320 and BAY-524 were highly potent and selective ATP-competitive inhibitors of BUB1 kinase activity with IC50 values in the single digit nanomolar range (at 10 micromolar ATP concentration). By monitoring phosphorylation of Thr120 in histone H2A, we showed that both compounds acted as potent BUB1 kinase inhibitors both biochemically and in human cells. We found that BUB1 inhibition substantially altered the chromosomal association of Shugoshin and the chromosomal passenger complex without major effects on global Aurora B function. Consequently, inhibition of BUB1 kinase clearly impaired chromosome arm resolution but, in stark contrast to depletion of BUB1 protein, only had a minor effect on cell cycle and SAC function. Importantly, BAY-320 and BAY-524 treatment sensitized cells to low doses of paclitaxel, synergistically affecting chromosome segregation and cell proliferation.
These findings are highly relevant to both our understanding of BUB1 kinase function during mitosis and the prospects of BUB1 as a target of anti-cancer therapies. In this regard, BAY-320 and BAY-524 are first-in-class inhibitors of BUB1 kinase and their potential utility as anti-cancer agents is being explored.
Citation Format: Anna P. Baron, Conrad von Schubert, Fabien Cubizolles, Gerhard Siemeister, Marion Hitchcock, Anne Mengel, Jens Schröder, Amaury Fernández-Montalván, Martin Lange, Franz von Nussbaum, Dominik Mumberg, Erich Nigg. Probing mitotic functions of BUB1 kinase using the small molecule inhibitors BAY-320 and BAY-524. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2725.
Abstract 2726: WWP2 is required for normal cell cycle progression
Authors: Choi Byeong Hyeok , Che Xun , Chen Changyan , Lu Luo , Dai Wei 
Published: July 2016

Abstract
WWP2 is a ubiquitin E3 ligase belonging to the Nedd4-like family. Given that WWP2 target proteins including PTEN that are crucial for regulating cell proliferation or suppressing tumorigenesis, we have asked whether WWP2 plays a role in controlling cell cycle progression. Here we report that WWP2 is necessary for normal cell cycle progression as its silencing significantly reduces the cell proliferation rate. We have identified that an isoform of WWP2 (WWP2-V4) is highly expressed in the M phase of the cell cycle. Silencing of WWP2 accelerates the turnover of cyclin E, which is accompanied by increased levels of phospho-histone H3 (p-H3) and cyclin B. Moreover, silencing of WWP2 results in compromised phosphorylation of AktS473, a residue whose phosphorylation is tightly associated with the activation of the kinase. Combined, these results strongly suggest that WWP2 is an important component in regulating the Akt signaling cascade, as well as cell cycle progression.
Citation Format: Byeong Hyeok Choi, Xun Che, Changyan Chen, Luo Lu, Wei Dai. WWP2 is required for normal cell cycle progression. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2726.
Abstract 2728: In silico identification of a MAD2-interacting motif in MAD2 spliced isoforms suggest a functional interaction with the spindle assemble checkpoint in cancer
Authors: Ramirez-Otero Miguel , Lopez-Saavedra Alejandro , Andonegui Marco , Diaz-Chavez Jose , Herrera Luis Alonso 
Published: July 2016

Abstract
Abnormal chromosome segregation plays a key role in cancer development. MAD2 is a component of the spindle assembly checkpoint (SAC), a cell cycle control mechanism that ensures an accurate segregation of chromosomes during mitosis. Changes in MAD2 expression have been associated with chemo-resistance both to spindle inhibitors and to DNA damaging agents. Also, a previous study has shown that the exogenous expression of MAD2β, a splicing variant of MAD2, was associated with resistance to Adriamycin and Vincristine in gastric cell lines. Additionally, we have previously identified that exogenous overexpression of MAD2γ upon paclitaxel-induced SAC activation in the colorectal cancer cell HCT116, reduces drug-induced mitotic arrest. These findings suggested a possible structural interaction of MAD2 isoforms with SAC components. To determine possible structural interactions between MAD2 isoforms and key SAC components (i.e. MAD1 and CDC20), we performed an in silico analysis of MAD2 isoforms, Interestingly, we found that alternative splicing of MAD2 generates a premature stop codon and a frameshift in exon 4 in MAD2γ and MAD2β. This change generates a new C-terminal region in MAD2γ and MAD2β isoforms that comprise 16 amino acids, which are not present in the major isoform (MAD2α). We aligned this region with the amino acid sequence of CDC20 from various species and identified a MAD2-interacting motif (MIM). This finding suggests that MAD2 isoforms may interact with the active conformation of MAD2 (C-MAD2). Since MAD2 isoforms and CDC20 may compete for the same region in MAD2, we propose a new model whereby MAD2 isoforms inhibits SAC by interfering with C-MAD2/CDC20 formation. This model helps to explain previous results where MAD2 isoforms over expression seem to have an opposite role in SAC signaling.
Citation Format: Miguel Ramirez-Otero, Alejandro Lopez-Saavedra, Marco Andonegui, Jose Diaz-Chavez, Luis Alonso Herrera. In silico identification of a MAD2-interacting motif in MAD2 spliced isoforms suggest a functional interaction with the spindle assemble checkpoint in cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2728.
Abstract 2734: Click colorimetric EdU proliferation and TUNEL assay: Conversion of click chemistry from fluorescent to colorimetric for use with bright field microscopy
Authors: Clarke Scott T. , Finnessy Carmen , Bosada Fernada M. , Armstrong Ben , O’Grady Michael 
Published: July 2016

Abstract
We present here the conversion of click chemistry fluorescence-based EdU proliferation assay and TUNEL apoptosis assay to use with bright field microscopy. Advantages of having a colorimetric signal are the retention of the click chemistry work flow while allowing for compatibility with standard H&E staining and protocols.
Proliferation using copper-catalyzed labeling of the thymidine analog EdU (ethynyl deoxyuridine) was introduced in 2007. This click-based assay has advantages over the traditional antibody based BrdU assay. The small molecule detection is simple, rapid and gives a bright signal useful for multiplexing. Additionally, recent improvements to the chemistry allow for GFP and R-PE compatibly with the EdU and TUNEL assays.
Several approaches for creating a colorimetric signal for EdU proliferation were attempted. The method presented here had the shortest protocol and uses a biotin-based click reaction followed by streptavidin -horseradish peroxidase (HRP) step. This two-step reaction creates an essentially covalent link between the EdU incorporated in the DNA and the enzyme reporter. Then standard HRP chromogens such as DAB were used to produce a signal marking the proliferating cells. Examples of proliferation using colorimetric EdU labeling in adult Zebrafish caudal fin, mouse cardiac, and rat intestine, mammary and uterine FFPE treated tissue are presented. Multiplexing with alkaline phosphatase for two color detection are also presented. Two color detection of EdU with BrdU or EdU with progesterone receptor (PR) are shown. Most HIER protocols are compatible with EdU detection. For EdU alone no HCl treatment is required. For EdU/BrdU double labeling the BrdU protocol for DNA revelation is used. Anti-BrdU mouse antibody clone MoBU-1 is used because of its lack of cross-reactivity with EdU.
Additionally, we present the click chemistry-based apoptotic TUNEL assay colorimetric detection using the same approach. Clickable biotin adapters are used to couple HRP to the ethynyl tails created by TdT enzyme extension at 3′ end of double stranded breaks. We provide examples of this late stage indicator of apoptosis visualized with DAB substrate and stained with standard H&E and other histological stains.
Citation Format: Scott T. Clarke, Carmen Finnessy, Fernada M. Bosada, Ben Armstrong, Michael O’Grady. Click colorimetric EdU proliferation and TUNEL assay: Conversion of click chemistry from fluorescent to colorimetric for use with bright field microscopy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2734.
Abstract 2745: A genetic screen to identify tumor suppressive DDR genes in breast cancer
Authors: Fagan-Solis Katerina D. , Gupta Gaorav P. 
Published: July 2016

Abstract
To maintain genomic integrity, cells utilize a DNA damage response (DDR) mechanism that 1) functions to repair damaged DNA efficiently and 2) commits cells to apoptosis if damage is irreparable. Failure of this mechanism results in genomic instability and cancer predisposition. Defects in DDR have been implicated in both sporadic and familial breast and ovarian cancer predisposition syndromes (e.g. BRCA1, BRCA2, and PALB2), although the specific pathway components that are disrupted have not been elucidated. In particular, an impaired DDR may contribute to the pathophysiology of triple-negative (ER-/PR-/HER2-) breast cancer (TNBC) due to the extent and complexity of the genomic instability that is observed. We identified the DNA damage sensing Mre11- Rad50-Nbs1 (MRN) complex as an essential mediator of the oncogene-induced DDR. Disrupting the MRN complex in mouse models promotes the development of genomically unstable, metastatic breast cancer. The clinical relevance of this pathway is highlighted by the observation that components of the Mre11 complex are perturbed in a significant fraction of human TNBCs, which correlates with clinical outcomes. However, lack of MRN suppression in a majority of TNBCs indicates that alternative DDR components may also be inactivated to promote breast cancer development. Our goal is to identify additional DDR genes that, when perturbed, promote the development of genomically unstable breast cancers. In order to accurately distinguish driver genes from bystander genes we have developed a platform to identify DDR genes that mediate oncogene-induced senescence in mammary epithelial cells using both shRNA and CRISPR pooled libraries. Analysis of newly identified tumor suppressor genes, compared to what is already known about Mre11 and p53 (positive controls), will enable us to determine causality of specific DDR mutations in breast cancer development and importantly, the genomic instability phenotype that is typical for TNBC. The insights gleaned from this study may ultimately provide the means to determine the optimal treatment regimen for each patient with TNBC, and to prevent over-treatment of patients where certain chemotherapies may not be effective.
Citation Format: Katerina D. Fagan-Solis, Gaorav P. Gupta. A genetic screen to identify tumor suppressive DDR genes in breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2745.
Abstract 2752: Characterization of the ATM-SPOP pathway in prostate cancer tumorigenesis
Authors: Fried Joshua , Boohaker Rebecca , Zeng Qinghua , Zhang Wei , Xu Bo 
Published: July 2016

Abstract
The Speckle type Poz Protein (SPOP), an E3 ubiquitin ligase adaptor, has recently been identified as the gene that has the most common somatic point mutations in prostate cancer. SPOP mutations are associated with genomic alterations, indicating a role for SPOP in the maintenance of genome stability. We, and others, have recently demonstrated a critical role of SPOP in the DNA damage response (DDR), suggesting SPOP mutants may represent a subgroup of patients that have hyper sensitivity to DNA damaging therapies. However, how SPOP mutations might impact its function and their roles in the progress of prostate tumorigenesis remain to be extensively studied. Genomic studies have found that SPOP mutations are clustered within its substrate binding pocket. Of a particular interest, Serine119 is found to be frequently mutated to Asparagine (S119N). Using computational modeling, we found that Ser119 resides in the SBC-MATH binding interface and is in close contact with the non-polar residue of the SPOP-binding consensus motif. Therefore we hypothesized that phosphorylation of Serine 119 might directly affect substrate binding. First we characterized prostate cancer cells expressing this mutation and we found that they displayed a suboptimal DNA damage response with prolonged DNA repair. Using an in situ proximity ligation assay, we demonstrate that Serine 119 is essential for SPOP ionizing irradiation induced interaction with the Ataxia Telangiectasia Mutated kinase (ATM), a major hub protein in the DDR. With the evidence of SPOP being a phospho-protein, we further provide in vitro evidence that ATM phosphorylates SPOP on Serine 119 in response to DNA damage. Characterization of the functional significance of ATM-mediated SPOP phosphorylation indicates a wide range of downstream targets regulating cell cycle progression and DNA repair. Taken together, our data reveal a critical pathway linking ATM and SPOP in regulation of prostate cancer initiation and therapeutic responses to DNA damage. This also provides the first evidence of a pathophysiological relevant mutation linked to ATM phosphorylation in the DDR.
Citation Format: Joshua Fried, Rebecca Boohaker, Qinghua Zeng, Wei Zhang, Bo Xu. Characterization of the ATM-SPOP pathway in prostate cancer tumorigenesis. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2752.
Abstract 2755: Regulation of 53BP1 by the structural nuclear protein NuMA
Authors: Salvador Moreno Naike 
Published: July 2016

Abstract
DNA double-strand breaks (DSBs) can cause genomic instability and cancer through point mutations and genomic translocations if they are not properly repaired. DSBs are repaired by two major pathways: homologous recombination (HR) or nonhomologous end joining (NHEJ). The cellular choice between these two pathways is critical to cell survival and is altered in cancers. 53BP1, which promotes NHEJ by blocking CtIP-dependent DNA resection, is a key protein mediating repair pathway choice. Here, we present a new negative regulation mechanism of 53BP1 that relies on the structural nuclear protein NuMA. Apart from its role in mitotic spindle assembly, NuMA influences chromatin organization during the interphase and modulates the chromatin response to DNA damage. We identified an interaction between NuMA and 53BP1 by proteomics analysis of a 53BP1 pull-down and confirmed this interaction by NuMA immunoprecipitation. We measured greater than 50% decreased 53BP1-NuMA binding in response to DSB, which suggest that, in the absence of DNA damage, NuMA may restrain 53BP1 diffusion. This hypothesis is supported by fluorescence correlation spectroscopy (FCS) measurements in cells expressing GFP-tagged 53BP1, as well as by microirradiation experiments in which NuMA overexpression or silencing inhibited or promoted 53BP1 recruitment at DNA damage sites, respectively. 53BP1 has an essential role in B cell class switch recombination (CSR) and mediates PARPi sensitivity in BRCA1-null cells. We will present how modulating NuMA expression affects both aspects of 53BP1 function. The results from our work will help to understand how 53BP1 is controlled, and shed light on the mechanisms regulating this modulator of PARPi sensitivity in the presence or absence of DNA damage.
Citation Format: Naike Salvador Moreno. Regulation of 53BP1 by the structural nuclear protein NuMA. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2755.
Abstract 2757: Mcl-1 dictates DNA double-strand break repair pathway choice
Authors: Chen Guo , Xu Ke , Xie Maohua , Owonikoko Taofeek K. , Ramalingam Suresh S. , Doetsch Paul W. , Deng Xingming 
Published: July 2016

Abstract
DNA double-strand breaks (DSBs) are mainly repaired by homologous recombination (HR) and non-homologous end-joining (NHEJ) pathways. The choice of pathway is a critical aspect of DSB repair that is poorly understood. We show that Mcl-1 acts as a functional switch in pathway choice between HR and NHEJ. Mcl-1 is cell cycle-regulated, with expression peaking in S/G2 phase via reduction of its ubiquitination when HR occurs. Mcl-1 depletion reduces HR and enhances NHEJ. Mcl-1 overexpression results in a net increase in HR over NHEJ. Mcl-1 promotes HR-dependent DSB repair following DNA replication stress, which contributes to maintenance of genomic integrity. Mcl-1 directly interacts with Ku via its BH1 and BH3 domains. This interaction is required for Mcl-1 to inhibit Ku-mediated NHEJ, and promote Mre11 complex-mediated DNA resection and HR-dependent DSB repair. Thus, Mcl-1, in addition to its antiapoptotic function, plays an unexpected role in directing DSB repair pathway choice by skewing the balance toward HR during cell cycle progression.
Citation Format: Guo Chen, Ke Xu, Maohua Xie, Taofeek K. Owonikoko, Suresh S. Ramalingam, Paul W. Doetsch, Xingming Deng. Mcl-1 dictates DNA double-strand break repair pathway choice. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2757.
Abstract 2759: USP21 stabilizes the BRCA2/Rad51 complex to ensure cancer genome maintenance
Authors: Liu Jinping , Kruswick Alex J. , Dang Hien , Tran Andy D. , Wang Xin W. , Philipp Philipp 
Published: July 2016

Abstract
Cancer is a disease of defective genome maintenance. Paradoxically, however, tumor growth relies on efficient DNA repair to mitigate the detrimental impact of replication-associated DNA double-strand breaks (DSBs). Deleterious mutations in BRCA2, a tumor suppressor that promotes homologous recombination (HR), consequently result in increased susceptibility to genotoxic stress in rapidly dividing tumor cells. While these findings underscore the importance of tightly controlled BRCA2 function for tumor growth, little is known about the factors that regulate this process. Here, we establish the ubiquitin-specific protease USP21 as a positive regulator of BRCA2 stability. USP21 interacts with, deubiquitinates and stabilizes the BRCA2/Rad51 complex and promotes efficient Rad51 loading to DSBs. As a result, depletion of USP21 decreases HR efficiency, causes an increase in DNA damage load and impairs tumor cell survival. Importantly, BRCA2 overexpression partially restores the USP21-associated HR defect. Moreover, we show that USP21 is overexpressed in hepatocellular carcinoma (HCC), where it promotes BRCA2 stability and inversely correlates with patient survival. These findings demonstrate a novel deubiquitination mechanism to control BRCA2 levels and point to USP21 as a potential therapeutic target in BRCA2-proficient tumors.
Citation Format: Jinping Liu, Alex J. Kruswick, Hien Dang, Andy D. Tran, Xin W. Wang, Philipp Philipp. USP21 stabilizes the BRCA2/Rad51 complex to ensure cancer genome maintenance. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2759.