bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract A07: The RAD51 paralog complex SWS1-SWSAP1 is critical for homologous recombination in the mouse
Authors: Prakash Rohit , Abreu Carla Manuela , Keeney Scott , Jasin Maria 
Published: April 2017

Abstract
Homologous recombination (HR), also termed homology-directed repair, is a major pathway for the repair of DNA double-strand breaks (DSBs) generated by DNA damaging agents, replication fork collapse and during meiosis. Failure to repair DSBs correctly causes genomic instability, leading to mutagenesis, and developmental defects. Moreover, defects in HR impact the response to many therapeutics. Components of the HR machinery include BRCA2 and five RAD51 paralogs, which are critical for RAD51 assembly onto single-stranded DNA, an important intermediate for homologous strand invasion. Disruption of these HR genes in mice results in embryonic lethality (pre-implantation to mid-gestation defects), developmental defects (e.g., sterility), and tumorigenesis. Recently, the Shu complex, composed of SWS1 and SWSAP1 subunits, was identified in human cells as a potential RAD51 paralog complex, since it functions with RAD51 to promote mitotic HR like its ortholog in yeast. Here, we show that the mouse Shu complex interacts with the ubiquitously expressed RAD51 recombinase and also with the meiosis-specific DMC1 recombinase. Knockout mice lacking one or both Shu complex subunits are viable and show no obvious developmental defects, except in gonads of both female and male mice, which are infertile. Analyses in males demonstrate that Shu complex is required for proper homologous synapsis and for the formation of RAD51 and DMC1 foci very early in meiotic prophase I. Our preliminary results indicate that the mouse Shu complex is also important for mitotic HR. Therefore, we propose that Shu complex ensures the assembly of RAD51 and DMC1 proteins into nucleoprotein filaments on resected DSBs to promote successful homology search and strand invasion, for completion of meiotic and mitotic recombination.
Citation Format: Rohit Prakash, Carla Manuela Abreu, Scott Keeney, Maria Jasin. The RAD51 paralog complex SWS1-SWSAP1 is critical for homologous recombination in the mouse [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr A07.
Abstract A12: CTCF facilitates DNA double-strand break repair by homologous recombination
Authors: Hilmi Khalid , Zhang Chenxi , Yu Zhenbao , Saad Amine , Richard Stephane , McCaffrey Luke , Alaoui-Jamali Moulay A. , Witcher Michael 
Published: April 2017

Abstract
The repair of DNA double strand breaks (DSB) is mediated via two major pathways, non-homologous end joining (NHEJ) or homologous recombination repair (HRR). Such repair is critical for cell survival and genome stability. Here, we report a new role for the multifunctional protein CTCF in facilitating the repair of DSB via the HRR pathway. CTCF is recruited to DSB through its zinc finger domain independently of poly(ADP-ribose) polymers catalyzed by PARP-1. CTCF ensures proper DSB repair kinetics in response to gamma-irradiation, and potentiates activation of the G2/M checkpoint. We find that CTCF regulates HRR through facilitating the recruitment of BRCA2, which is dependent on CTCF PARylation. In contrast, CTCF does not influence the recruitment, or retention, of the NHEJ protein 53BP1 to DSB. We also see that loss of CTCF is associated with hypersensitivity to DNA damaging inducing agents and inhibitors of PARP-1. Taken together, our findings establish for the first time that CTCF is an important regulator of the HRR pathway and indicate that tumors harboring hypo-PARylated CTCF may show elevated sensitivity to PARP inhibition.
Citation Format: Khalid Hilmi, Chenxi Zhang, Zhenbao Yu, Amine Saad, Stephane Richard, Luke McCaffrey, Moulay A. Alaoui-Jamali, Michael Witcher. CTCF facilitates DNA double-strand break repair by homologous recombination [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr A12.
Abstract A24: A genome-wide RNAi screen identifies synthetic lethality of CX-5461 with homologous recombination repair deficiency in ovarian cancer
Authors: Yan Shunfei , Chan Keefe T. , Simpson Kaylene J. , Sanij Elaine , Sheppard Karen E. , Hannan Katherine M. , Hannan Ross D. , Pearson Richard B. 
Published: April 2017

Abstract
Cancer is characterized by deregulated cell growth and proliferation, both of which are associated with hyperactivation of ribosome biogenesis. Inhibition of ribosome biogenesis using CX-5461, a specific inhibitor of RNA polymerase I-dependent transcription, has shown therapeutic efficacy in a MYC driven B-cell lymphoma mouse model, which is enhanced when used in combination with the mTORC1 inhibitor Everolimus. However, the therapeutic potential of CX-5461 in solid cancers is yet to be determined.
Our preliminary data utilizing a panel of 36 ovarian cancer (OVCA) cell lines suggest that acute CX-5461 treatment results in cell cycle arrest and does not induce apoptosis. We hypothesize that the identification of genes that can be targeted to cooperate with CX-5461 will define novel drug combinations for the improved treatment of OVCA. Therefore, we performed a genome-wide RNAi screen to identify synthetic lethal genes with CX-5461 in the high-grade serous ovarian cancer (HGSOC) cell line OVCAR4. Pathway enrichment analysis of the candidate hits showed significant enrichment in the homologous recombination DNA repair (HR) pathway. Synergy with CX-5461 was validated in multiple HGSOC cell lines by both genetic and pharmacological inhibition of HR pathway components. We are currently investigating the mechanism of this synergy and will further assess efficacy in vivo.
As HR deficiency is observed in 20% of OVCA patients, we suggest that future application of our studies will lead to new therapeutic options to improve the survival of this cohort of patients.
Citation Format: Shunfei Yan, Keefe T. Chan, Kaylene J. Simpson, Elaine Sanij, Karen E. Sheppard, Katherine M. Hannan, Ross D. Hannan, Richard B. Pearson. A genome-wide RNAi screen identifies synthetic lethality of CX-5461 with homologous recombination repair deficiency in ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr A24.
Abstract A32: Exploring the interplay between nucleotide excision repair and DNA replicative stress
Authors: Drobetsky Elliot , Bélanger François , Angers Jean-Philippe , Fortier Émile , Costantino Santiago , Wurtele Hugo 
Published: April 2017

Abstract
Ultraviolet (UV) light causes highly genotoxic DNA lesions that are removed by nucleotide excision repair (NER), and NER is critical for preventing UV-associated skin cancers. UV-induced DNA lesions block the progression of DNA polymerases, leading to replicative stress and genomic instability. Upon UV, the ataxia-telangectasia and rad3 related (ATR) kinase is rapidly activated, leading to cell-cycle arrest, inhibition of replication origin firing, and stabilization of blocked replication forks. Intriguingly, previous data indicated that reduced ATR activity causes profound NER defects specifically in S phase cells. Moreover many model cancer cell lines, including a majority of melanoma lines, present striking S phase-specific NER defects.
We used the yeast S. cerevisiae as model to investigate NER activity during S phase. We optimized a novel flow cytometry-based assay to quantify NER as a function of cell cycle in this organism. Using this assay we demonstrate that, as for human cells, deletion of the yeast ATR homolog Mec1 causes NER defects uniquely in S, and that initiation of DNA replication is prerequisite for manifestation of this defect. S phase-specific NER was perturbed by mutations in various genes encoding key DNA damage response factors that regulate, e.g. cell cycle checkpoints, chromatin remodeling, and homologous recombination. Our data also reveal a strong correlation between S phase-specific NER defects and elevated RPA focus formation in mutants that are sensitive to replicative stress. Finally we demonstrate that modulation of RPA levels strongly influences NER activity specifically during S in human cancer cell lines. Overall, our data indicate that mutations in a multitude of DNA damage response pathways cause inordinate sequestration of RPA at stalled replication forks, thereby reducing the availability of this factor to perform its essential role in NER. This has important implications for our understanding of UV-induced skin cancer development in humans.
Citation Format: Elliot Drobetsky, François Bélanger, Jean-Philippe Angers, Émile Fortier, Santiago Costantino, Hugo Wurtele. Exploring the interplay between nucleotide excision repair and DNA replicative stress [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr A32.
Abstract A33: Defect in S phase cell cycle checkpoint renders tumours vulnerable to CHK1 inhibitor single-agent treatment in vitro and in vivo
Authors: Oo Zay Yar , Stevenson Alexander , Lanagan Catherine , Spoerri Loredana , Larsen Jill , Gabrielli Brian 
Published: April 2017

Abstract
CHK1 inhibitors are being investigated as chemosensitizing agents with agents that increase replication stress. Here we have investigated the molecular basis of sensitivity to CHK1 inhibitors as single agents in melanoma and lung cancer. We have found that sensitivity in vitro and in vivo to single agent CHK1 inhibitor is loss of the S phase cell cycle checkpoint response. This is through a number of mechanisms including the uncoupling of CHK1 activation with the destabilization of CDC25A. Loss of checkpoint by over-expressing components of the checkpoint or inhibition of Wee1, covert CHK1 inhibitor insensitive cells to sensitive, and similarly depletion of CDC25A reduces CHK1 inhibitor sensitivity in sensitive lines. Loss of the S phase checkpoint provides cells with an adaptive advantage through introduction of moderate levels of genomic instability. The increased DNA damage found with CHK1 inhibitor treatment is not sufficient to induce cell death, but also involves a mechanism that is dependent in part on DNA-PK activity. Loss of S phase checkpoint function is predicted for &lt;25% of melanomas and non-small cell lung squamous cell cancers. This is independent of other known risk factors, suggesting a significant proportion of melanoma and lung cancer patients could benefit from treatment with these drugs.
Note: This abstract was not presented at the conference.
Citation Format: Zay Yar Oo, Alexander Stevenson, Catherine Lanagan, Loredana Spoerri, Jill Larsen, Brian Gabrielli. Defect in S phase cell cycle checkpoint renders tumours vulnerable to CHK1 inhibitor single-agent treatment in vitro and in vivo [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr A33.
Abstract A37: Development of screening methods to identify Translesion DNA Synthesis inhibitors
Authors: Villafañez Florencia , García Alejandra Iris , Pansa María Florencia , Carbajosa Sofía , Bocco José Luis , Soria Gastón 
Published: April 2017

Abstract
Translesion DNA synthesis (TLS) is a DNA damage tolerance process that employs specialized polymerases to bypass DNA damage during replication. Recent evidence indicates that TLS is a key process that promotes the development of resistance to cancer treatments that induce DNA damage (i.e. Cisplatin). Thus, the inhibition of TLS emerges as a promising strategy for cancer therapy. However, to date, specific chemical inhibitors of TLS are not available.
The main goal of our project is to identify specific inhibitors of TLS that can be used as a proof of concept in cancer therapy by developing cell-based assays that explore TLS markers. Our rational is that since TLS polymerases recruitment to sites of DNA damage is a key step for TLS success, we can indirectly monitor TLS efficiency in a given context by studying two key markers of TLS polymerases recruitment: 1) The mono-ubiquitylation of the replication auxiliary factor PCNA and 2) the accumulation of a TLS polymerase into replication foci. We thus developed two screening methods that allow us to promptly identify inhibitors of PCNA ubiquitylation and TLS polymerases recruitment into DNA damage sites. The first marker, PCNA mono-ubiquitylation, is assessed through a western-Blot-based platform where the identification of unmodified PCNA and mono-ubiquitylated PCNA are achieved by two different antibodies coupled to fluorescent infrared detection using a fluorescence scanner. For the second marker, TLS polymerase recruitment to damage sites, we developed stable cell lines expressing TLS polymerases fused to fluorescent proteins and we analyze polymerases recruitment through an imaging-based assay.
In this poster we describe the results of a pilot screening using an open source library of kinase inhibitors from GlaxoSmithKline (known as PKIS2), and the early validation of the identified hits.
Citation Format: Florencia Villafañez, Alejandra Iris García, María Florencia Pansa, Sofía Carbajosa, José Luis Bocco, Gastón Soria. Development of screening methods to identify Translesion DNA Synthesis inhibitors [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr A37.
Abstract A42: Identification of glutamate and aspartate ADP-ribosylation sites onto histones by mass mass spectrometry
Authors: Gagné Jean-Philippe , Roux-Dalvai Florence , Defoy Daniel , Droit Arnaud , Michael Hendzel J. , Poirier Guy G. 
Published: April 2017

Abstract
Chromatin structure and function is regulated by histone post-translational modifications. Histone proteins are subject to a variety of post-translational modifications that can work combinatorially to alter the transcriptional state or the repair of DNA damage. The landscape of histone modifications includes mono- and poly(ADP-ribosylation), which can directly alter nucleosome structure and DNA accessibility. ADP-ribosylation occuring on glutamate and aspartate residues was the most intensively studied histone ADP-ribosylation modification in the past, primarily because these carboxylester-type ADP-ribose–protein bonds were the most susceptible to hydroxylamine hydrolysis, a particularly fast and efficient method of protein de-ADP-ribosylation. Taking advantage of hydroxylamine-based developments in the identification of ADP-ribosylated residues by liquid-chromatography tandem mass spectrometry (LC-MS/MS), we generated a repertoire of glutamate- and aspartate-specific ADP-ribosylation sites onto histones. In our study, high confidence MS/MS-assigned ADP-ribosylation site identification onto a combination of in vitro and in vivo ADP-ribosylated histones revealed that all five major classes of histones are targets for D/E ADP-ribosylation. We found that the histone tails are not the sole location of the sites of ADP-ribosylation. Significant ADP-ribosylation sites were located in central globular regions of histones adding to the complexity of the histone modification landscape.
Citation Format: Jean-Philippe Gagné, Florence Roux-Dalvai, Daniel Defoy, Arnaud Droit, Hendzel J. Michael, Guy G. Poirier. Identification of glutamate and aspartate ADP-ribosylation sites onto histones by mass mass spectrometry [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr A42.
Abstract A43: TFG-TEC oncogene modulates beta-enolase expression via both promoter activation and epigenetic modification
Authors: Kim Ah-young , Lim Bobae , Choi JeeHyun , Kim Jungho 
Published: April 2017

Abstract
Recurrent chromosome translocations are the hallmark of many human cancers. A proportion of human extraskeletal myxoid chondrosarcomas (EMCs) are associated with the characteristic chromosomal translocation t(3;9)(q11-12;q22), which results in the formation of a chimeric protein in which the N-terminal domain of the TRK-fused gene (TFG) is fused to the translocated in extraskeletal chondrosarcoma (TEC; also called CHN, CSMF, MINOR, NOR1, and NR4A3) gene. The oncogenic effect of this translocation may be due to the higher transactivation ability of the TFG-TEC chimeric protein; however, downstream target genes of TFG-TEC have not yet been identified. The results presented here demonstrate that TFG-TEC activates the human beta-enolase promoter. EMSAs, ChIP assays, and luciferase reporter assays revealed that TFG-TEC upregulates beta-enolase transcription by binding to two NGFI-B response element motifs located upstream of the putative transcription start site. In addition, northern blot, quantitative real-time PCR, and western blot analyses showed that overexpression of TFG-TEC up-regulated beta-enolase mRNA and protein expression in cultured cell lines. Finally, ChIP analyses revealed that TFG-TEC controls the activity of the endogenous beta-enolase promoter by promoting histone H3 acetylation. Overall, the results presented here indicate that TFG-TEC triggers a regulatory gene hierarchy implicated in cancer cell metabolism. This finding may aid the development of new therapeutic strategies for the treatment of human EMCs.
Citation Format: Ah-young Kim, Bobae Lim, JeeHyun Choi, Jungho Kim. TFG-TEC oncogene modulates beta-enolase expression via both promoter activation and epigenetic modification [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr A43.
Abstract B13: Involvement of PAF1 complex in the DNA damage response
Authors: Park Garin , Kim Nari , Yoo Joo-Yeon 
Published: April 2017

Abstract
PAF1 complex is a transcriptional complex composed of PAF1, CTR9, CDC73, LEO1, RTF1 and SKI8 in human. It plays a key role in the regulation of every step of transcription, from initiation to termination. PAF1 complex associates with RNA polymerase ΙΙ during transcription, and regulates modification patterns of surrounding histones or chromatin structure via recruitment of histone modifying enzymes or chromatin remodeling factors to the actively transcribed site. In yeast, PAF1 complex has been also proposed to involve in other DNA associated processes, like DNA recombination, replication, and repair. However, detailed molecular mechanism of this regulation has not been fully understood. We recently observed significant DNA breakage in the PAF1 complex depleted cells. DNA repair of artificially introduced DNA break by I-SceI endonuclease was less efficiently repaired in these cells, indicating the connection between the DNA damage repair and active transcription. The molecular mechanism of this regulation will be discussed.
Citation Format: Garin Park, Nari Kim, Joo-Yeon Yoo. Involvement of PAF1 complex in the DNA damage response [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr B13.
Abstract B34: Development of novel small molecule inhibitors targeting DNA repair proteins
Authors: Pawelczak Katherine S. , Gavande Navnath , VanderVere-Carozza Pamela , Turchi John 
Published: April 2017

Abstract
More than 1.6 million new cases of cancer will be diagnosed in the US in 2016 and a third of these will be from solid tumor of the lung, pancreas, breast, and ovary. These cancers represent a continuing clinical challenge in treatment and together account for over 250,000 deaths in the US alone, representing over 40% of all cancer deaths. There are limited therapeutic options for these patients, and targeted and combination therapies remain necessary for treating these aggressive cancers. The opportunity exists to exploit recent scientific advances in our knowledge of the underlying biology behind these cancers to create novel targeted therapeutics to dramatically enhance patient response to therapy and ultimately survival. To this end, we have developed a series of novel small chemical molecules that disrupt critical protein-DNA interactions in the nucleotide excision and non-homologous end joining DNA repair pathways. It is well understood that various cancer treatments like cisplatin, etoposide and ionizing radiation impart their chemotherapeutic effect by the formation of direct DNA damage which block DNA replication and transcription culminating in apoptosis. It is also well established that repair of this DNA damage by various DNA repair pathways reduces the effectiveness of chemo- or radio- therapy. It is our contention, borne out by analysis of clinical data to be presented on the development of our DNA repair inhibitors, that inhibition of these DNA repair pathways sensitizes these difficult to treat cancers to traditional DNA-damaging therapy. We anticipate both direct mechanisms of action on the repair pathways and synthetic lethal interactions can be exploited for therapeutic benefit. The series of novel small molecule inhibitors that we have developed targeting DNA repair proteins exhibit single-agent anti-cancer activity in cancer cell lines, and potentiate cellular sensitivity to chemotherapy and ionizing radiation treatment. Our data demonstrate that this class of inhibitors can be further developed as anti-cancer therapeutics with considerable potential to be used in conjunction with radiation therapy and other cancer therapies that induce DNA damage.
Citation Format: Katherine S. Pawelczak, Navnath Gavande, Pamela VanderVere-Carozza, John Turchi. Development of novel small molecule inhibitors targeting DNA repair proteins [abstract]. In: Proceedings of the AACR Special Conference on DNA Repair: Tumor Development and Therapeutic Response; 2016 Nov 2-5; Montreal, QC, Canada. Philadelphia (PA): AACR; Mol Cancer Res 2017;15(4_Suppl):Abstract nr B34.