bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 3771: Tank-binding kinase 1 associates with centrosomes and regulates microtubule dynamics and mitosis
Authors: Pillai Smitha R. , Nguyen Jonathan , Johnson Joseph , Haura Eric , Coppola Domenico , Chellappan Srikumar 
Published: August 2015

Abstract
TANK Binding Kinase 1 (TBK1) regulates interferon signaling and NFκB function by acting as a non-canonical IκB kinase. TBK1 also participates in RalB-mediated inflammatory responses and contributes to the survival of non-small cell lung cancers (NSCLC) driven by oncogenic KRAS. In addition, TBK1 could phosphorylate and activate Akt, modulate autophagy and alter the autocrine cytokine network in cancer cells indicating oncogenic roles in addition to its immune regulatory functions. Our studies reveal that TBK1 plays a novel and direct role in promoting mitotic progression of lung cancer cells by phosphorylating multiple substrates during mitosis as well as by modulating microtubule dynamics. Levels of active phospho-TBK1 are elevated in mitotic cells where it localized to centrosomes, mitotic spindles and midbody as seen by confocal microscopy. Inhibition of TBK1 by kinase inhibitors such as BX795, Amlexanox, MRT67037 or depletion of TBK1 by shRNA resulted in mitotic defects and decreased the number of mitotic cells. TBK1 could interact with the centrosomal protein CEP170 and the nuclear mitotic apparatus protein NuMA as seen by GST binding assays, immunoprecipitation-western blot assays and proximity ligation assays. In addition, TBK1 could phosphorylate CEP170 and NuMA in in vitro kinase assays; mass spectrometry analysis revealed that TBK1 phosphorylated 12 serine residues and a threonine residue of CEP170 and five serine residues of NuMA. Inhibition or depletion of TBK1 prevented the centrosomal localization of CEP170 and the association of NuMA with the spindle poles. TBK1 depletion in A549 and H1650 cells resulted in more stable microtubules; further, depletion of TBK1 inhibited the interaction of CEP170 with the microtubule depolymerase Kif2b and the binding of NuMA to Dynein, resulting in mitotic abnormalities or mitotic arrest. In addition, inhibition of specific interaction between TBK1 and CEP170 using a 13 amino acid peptide resulted in inhibition of mitosis, enhanced microtubule stability and mitotic defects. These results are paradigm shifting that suggest TBK1 plays a significant role in regulating microtubule dynamics and mitotic progression of cells and this might have significant relevance to cancer as well as innate immune response.
Citation Format: Smitha R. Pillai, Jonathan Nguyen, Joseph Johnson, Eric Haura, Domenico Coppola, Srikumar Chellappan. Tank-binding kinase 1 associates with centrosomes and regulates microtubule dynamics and mitosis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3771. doi:10.1158/1538-7445.AM2015-3771
Abstract 3773: Plk1-mediated stabilization of 53BP1 suppresses centrosome abnormal amplification
Authors: Yim Hyungshin , Woo Sang-Uk , Shin Sol-Bi , Erikson Raymond L. 
Published: August 2015

Abstract
Mammalian Plk1 has been studied as an essential factor in regulating mitotic events through the phosphorylation of several Plk1-specific substrates. Here we show that in mitosis 53BP1 binds to the C-terminal polo-box domain of Plk1 and is a substrate for Plk1 in vitro. 53BP1 is hyper-phosphorylated and its level is up-regulated in cells expressing wild type Plk1 (Plk1-WT), but not in cells expressing a kinase-defective mutant (Plk1-KM). Depletion of Plk1 reduces the level of 53BP1 which is restored in cells treated with MG132. In cells expressing Plk1-KM but not in Plk1-WT cells, 53BP1 interacts with Mdm2 suggesting that 53BP1 turnover is regulated by Plk1-mediated phosphorylation. In mitosis, 53BP1 colocalizes with Plk1 to the centrosome and the spindle pole. Down-regulation of 53BP1 by shRNA induces multiple centrioles, multiple spindle poles, and mis-orientation of poles in HeLa cells. The data suggest that the phosphorylation of 53BP1 by Plk1 regulates its stability, and that this biochemical event plays a crucial role in modulating chromosomal amplification which ensures bipolarity in mitosis.
Citation Format: Hyungshin Yim, Sang-Uk Woo, Sol-Bi Shin, Raymond L. Erikson. Plk1-mediated stabilization of 53BP1 suppresses centrosome abnormal amplification. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3773. doi:10.1158/1538-7445.AM2015-3773
Abstract 3774: Investigating the role of CDC25B in inhibition of cellular proliferation
Authors: Lee Caleb C. , Manfredi James 
Published: August 2015

Abstract
CDC25B is a dual specificity phosphatase that activates cyclin-dependent kinases to trigger entry into mitosis and is required for re-entry into mitosis after DNA damage. Four isoforms of CDC25B are known to be expressed and some differences in their role in dividing cells versus continuation of the cell cycle after DNA damage have been shown.
As an oncogene, CDC25B is upregulated by c-Myc and activated by Aurora-A. In humans, CDC25B is overexpressed in multiple tumor types and increased levels correlate with worsening tumor grade. In a transgenic mouse model, overexpression of CDC25B in the mammary glands led to accelerated mammary epithelial proliferation resulting in hyperplasia and the formation of tumors when exposed to the carcinogen DMBA. In vitro, co-transfection of CDC25B with Ras allows for transformation of MEF’s.
Surprisingly, given the establishment of CDC25B as an oncogene, colony formation assays using ectopic expression of CDC25B in transformed cell lines reveal an anti-proliferative effect. Although CDC25B has been shown to cause DNA damage and activates p53, our data show that colony formation is decreased independent of p53 status. Preliminary data reveal a role for Ras inhibition as a cause of this anti-proliferative effect. Co-transfection of CDC25B and activated Ras results in decreased expression of the ectopic Ras protein in several cell lines tested. Furthermore overexpression of CDC25B abrogates the G2 arrest and decreases cell viability after pulse treatment with doxorubicin. Taken together, these data suggest a novel mechanism by which CDC25B may inhibit proliferation by decreasing Ras expression.
Citation Format: Caleb C. Lee, James Manfredi. Investigating the role of CDC25B in inhibition of cellular proliferation. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3774. doi:10.1158/1538-7445.AM2015-3774
Abstract 3778: Inhibition of NF-κB translocation induces G0/G1 arrest and downregulates thymidylate synthase in colorectal cancer
Authors: Nagaraju Ganji Purnachandra , Olatunji Alese , Gupta Sandhya , Shoji Mamoru , El-Rayes Bassel F. 
Published: August 2015

Abstract
Purpose Objectives: Cell cycle progression and DNA synthesis are essential steps in cancer cell growth and resistance. Thymidylate synthase (TS) is a therapeutic target for 5FU. Curcumin is a potent inhibitor of NF-κB. We tested the hypothesis that NF-κB translocation inhibition by curcumin and its analogs can inhibit cell cycle progression and downregulate TS levels in colorectal cell lines.
Methods: Two colorectal cancer cell lines were usedHCT-116 and HT-29. Cells were either untreated (control) or treated with curcumin (20μM), EF31 (7.5μM for HCT-116 and 2.5μM for HT-29) and UBS109 (620nM for HCT-116 and 1.25μM for HT-29) for 24 hours. Western blot and RT-PCR analyses were carried out to determine the effect of curcumin and its analogues EF31 and UBS109 on different signal molecules involved in cell cycle arrest and DNA synthesis. Electromobility shift assay (EMSA) was performed in colon cancer cells to evaluate the effects of curcumin and its analogues on NF-κB activity. A subcutaneous xenograft mouse model was used to evaluate the in vivo effects of curcumin analogues.
Results: Treatment with curcumin and its analogues inhibited cyclin D1, pRb and E2F-1 at the transcriptional and translational level and induced p21, leading to G0/G1 cell cycle arrest. NF-κB over-expression induced E2F-1 and TS protein and mRNA levels in both cell lines. Arrest in the G0/G1 phase was associated with downregulation of the transcription factor E2F-1 and its target gene TS. Similar effects were observed in tumors from animals treated with EF31 and UBS109. Further, EF31 and UBS109 treatment significantly decreased the tumor growth compared to untreated tumors.
Conclusion: In this study, we present in vitro and in vivo data to support the use of curcumin analogs in colorectal cancer based on their ability to reduce expression of proteins important for DNA repair and cell cycle progression leading to cell cycle arrest and tumor shrinkage. Accordingly, combining curcumin analogs with chemotherapy is a rational approach for future drug development in colorectal cancer.
Citation Format: Ganji Purnachandra Nagaraju, Alese Olatunji, Sandhya Gupta, Mamoru Shoji, Bassel F. El-Rayes. Inhibition of NF-κB translocation induces G0/G1 arrest and downregulates thymidylate synthase in colorectal cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3778. doi:10.1158/1538-7445.AM2015-3778
Abstract 3779: Mutational analysis of MCPH1 C-terminal tandem BRCT domain reveals residues essential for cell cycle arrest
Authors: Golubeva Volha A. , Woods Nicholas T. , Monteiro Alvaro N.A. 
Published: August 2015

Abstract
In this study, the C-terminal tandem BRCT domain of human microcephalin 1 protein (MCPH1) was mutagenized in Saccharomyces cerevisiae yeast to identify residues critical for the cell cycle arrest. Deleterious variants in MCPH1 causing the loss of the protein function are associated with primary microcephaly, characterized by decreased cerebral cortex size and mild mental retardation. The tandem BRCT domain of MCPH1 (amino acids 640-833) recognizes phospho-serine/threonine motifs, including □-H2AX, necessary for DNA damage response and cell cycle regulation. Expression of this region of human MCPH1 tethered to DNA in yeast through the Gal4 DNA binding domain (and not through the interaction with the Gal4 activation domain), results in growth inhibition and a small colony phenotype. To detect the essential residues of the MCPH1 tandem BRCT, mutations were randomly introduced into this region using error-prone polymerase chain reaction. The mutants were then transformed into yeast and transformants showing abrogation of the small colony phenotype were isolated and the specific mutations were assessed by sequencing. Screening revealed 34 missense, 4 nonsense, and 8 frameshift variants, and one large deletion of 72 base pairs. The 34 missense variants were further analyzed in silico by alignment with the BRCA1 tandem BRCT. Out of 34 missense variants, four (T694A, L755P, F756V, and S819P) were identified in two or more colonies. One of the mutated residues (T653) is involved in direct hydrogen bonding with □-H2AX, which is likely disrupted by the amino acid change induced during mutagenesis (T653I). Interestingly, when aligned with BRCA1, 16 (47%) of MCPH1 missense variants matched to a corresponding site in BRCA1 previously reported as a missense variant with a functional impact. MCPH1 residues 653, 756, and 819 all corresponded to amino acids in BRCA1 known for their likely pathogenicity. Thus, this study identifies functional determinants in MCPH1 C-terminal domain potentially involved in cell cycle regulation. Taken together, our results suggest that variants in BRCT domain containing proteins, can be clinically annotated by making comparative alignments with the conserved residues of BRCA1 BRCT. Structural inference using BRCT paralogs might aid in the clinical annotation for variants lacking genetic data.
Citation Format: Volha A. Golubeva, Nicholas T. Woods, Alvaro N.A. Monteiro. Mutational analysis of MCPH1 C-terminal tandem BRCT domain reveals residues essential for cell cycle arrest. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3779. doi:10.1158/1538-7445.AM2015-3779
Abstract 3781: Effects of a novel microtubule inhibitor, AK301 on Apc heterozygote colon cells
Authors: Chopra Avijeet , Anderson Amy , Rosenberg Daniel , Giardina Charles 
Published: August 2015

Abstract
Over 80% of the sporadic colon cancers harbor somatic mutations of APC, predominantly resulting in APC protein lacking its C-terminal end. The basic region within the C-terminus of APC interacts with microtubules to promote polymerization, a process essential for establishment of cell polarity and faithful segregation of chromosomes during mitosis. Truncation mutations of Apc have been proposed to act in a dominant negative manner to slow microtubule growth and anchoring. We recently identified a novel microtubule inhibitor, 4-(3-chlorophenyl)piperazin-1-yl) (2-ethoxyphenyl)methanone, referred to as AK301. Our in vitro tubulin polymerization assay indicates that AK301 disrupts microtubule polymerization, but does not completely abrogate microtubule growth. In addition, in silico molecular docking predicts a novel and unique binding orientation of AK301 to the colchicine-binding domain of β-tubulin. We examined the effects of AK301 on microtubule dynamics in Apc+/+ and ApcMin/+ cells. Here we show that ApcMin/+ cells normally maintain shorter microtubules under normal growth conditions. Following treatment with AK301, mutant cells show more extensive cytoskeletal and mitotic spindle abnormalities. Moreover, AK301-treated ApcMin/+ cells showed centrosome declustering, evident from multiple Aurora A kinase foci; bipolar assembly was observed in the corresponding untreated ApcMin/+ cells or treated Apc+/+ cells. Overall, AK301 and its derivatives may help illuminate the regulation of microtubule dynamics in Apc mutant cells and provide insight into the consequences of targeting their microtubule assembly defect.
Note: This abstract was not presented at the meeting.
Citation Format: Avijeet Chopra, Amy Anderson, Daniel Rosenberg, Charles Giardina. Effects of a novel microtubule inhibitor, AK301 on Apc heterozygote colon cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3781. doi:10.1158/1538-7445.AM2015-3781
Abstract 3785: Cdk1 coordinates telomere replication by regulating the temporal recruitment of telomerase and the CST complex
Authors: Gopalakrishnan Veena , Liu Chang-Ching , Poon Lai Fong , Yan Tingdong , Li Shang 
Published: August 2015

Abstract
Telomeres are nucleoprotein structures that cap the ends of linear chromosomes. They ensure genomic stability and complete replication of the genome. The enzyme telomerase mediates telomere elongation. Considering that telomerase is up-regulated in about 90% of human cancers and telomerase-mediated telomere elongation is significantly deregulated in cancers, insights from our study can be used to target the telomere replication machinery for therapeutic intervention in cancer. In our study, we use budding yeast to understand the mechanism of telomere maintenance. In budding yeast, Cdk1 coordinates the cell cycle-dependent elongation of telomere by telomerase. Cdk1 phosphorylates the telomere-specific ssDNA binding protein, Cdc13, which promotes the recruitment of telomerase to the telomere and thereby, telomere elongation. Cdc13 is also an integral part of the CST (Cdc13-Stn1-Ten1) complex, which provides the protective cap at the telomere and inhibits telomere elongation by telomerase. Therefore, the telomere length homeostasis is balanced between these two telomerase-extendable and CST-unextendable states. However, the cellular signaling that regulates the switch between these two states is largely unknown. Here we show that Cdk1 phosphorylates Stn1 sequentially to that of Cdc13. Cdk1-dependant phosphorylation of Stn1 is essential for telomere maintenance in vivo, CST stability and the inhibition of telomerase at the telomeres. By controlling the timing of Cdc13 and Stn1 phosphorylation during cell cycle progression, Cdk1 coordinates the recruitment of telomerase holoenzyme and CST complex to the telomeres respectively and hence the switch between the telomerase-extendable and CST-unextendable states of the telomeres in budding yeast. With increasing evidence of human CST complex being involved in telomere length maintenance, the results from my study will provide insights into telomere homeostasis in humans and its disruption in cancers.
Citation Format: Veena Gopalakrishnan, Chang-Ching Liu, Lai Fong Poon, Tingdong Yan, Shang Li. Cdk1 coordinates telomere replication by regulating the temporal recruitment of telomerase and the CST complex. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3785. doi:10.1158/1538-7445.AM2015-3785
Abstract 3787: EphrinB1 is a novel microtubule associated protein whose expression may predict sensitivity to taxane
Authors: Vermeer Paola D. , Colbert Paul L. , Vermeer Daniel W. , Wieking Bryant G. , Lee John H. 
Published: August 2015

Abstract
Mitosis is a complex sequence of highly regulated events that ensures the proper segregation of sister chromatids into daughter cells. At the heart of the mitotic machinery lie the microtubules. Microtubules (MTs) are components of the cytoskeleton made up of polymerized alpha and beta tubulin dimers. MT structure and function must be maintained throughout the cell cycle to ensure proper execution of mitosis and cellular homeostasis. It has previously been reported that the protein tyrosine phosphatase, PTPN13, localizes at centrosomes from interphase, through metaphase and dramatically shifts to the spindle midzone during anaphase. During telophase, PTPN13 accumulates at the midzone, becoming concentrated at the center of the midbody during cytokinesis. We have previously demonstrated that the HPV16 E6 oncoprotein binds PTPN13 and leads to its degradation. Given PTPN13's localization to distinct compartments during mitosis/cytokinesis, we speculated that HPV infection may affect the process of mitosis. In addition, the newly appreciated roles of the PTPN13 phosphatase substrate, EphrinB1, in oncogenesis, further prompted us to define its role in mitosis. Here we report that EphrinB1 co-localizes with MTs during all phases of the cell cycle. Specifically, unphosphorylated EphrinB1 directly binds tubulin, while its phosphorylated form lacks MT binding. These characteristics are hallmarks of microtubule associated proteins (MAPs) and suggest that EphrinB1 is a novel MAP. Importantly, we demonstrate that expression of PTPN13 correlates with sensitivity to taxanes while its absence may confer resistance. In addition, we show that EphrinB1 expression affects taxane response in vitro and in vivo. We speculate that this reflects PTPN13's modulation of EphrinB1 phosphorylation and suggest that EphrinB1 is an important contributor to taxane sensitivity/resistance phenotypes in epithelial cancers. HPV infection or functional mutations of PTPN13 in non-viral cancers may predict taxane sensitivity.
Note: This abstract was not presented at the meeting.
Citation Format: Paola D. Vermeer, Paul L. Colbert, Daniel W. Vermeer, Bryant G. Wieking, John H. Lee. EphrinB1 is a novel microtubule associated protein whose expression may predict sensitivity to taxane. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3787. doi:10.1158/1538-7445.AM2015-3787
Abstract 3792: SKP2 supports cell proliferation and is regulated by Notch signaling in myoblasts and embryonal rhabdomyosarcoma
Authors: Rota Rossella , Adesso Laura , Conti Beatrice , Ciarapica Roberta , De Raimondi Lavinia , Salvo Maria , Rodriguez Sonia , Carlesso Nadia , Miele Lucio , Locatelli Franco 
Published: August 2015

Abstract
Background:
Rhabdomyosarcoma (RMS) in a pediatric tumor of myogenic origin. It includes two subtypes: embryonal and alveolar. Embryonal RMS (ERMS) cells express key myogenic factors such as MyoD and Myogenin, but proliferate indefinitely and have lost the ability to terminally differentiate into skeletal myofibers. Differently from the alveolar tumors bearing specific chromosomal translocations, ERMS has cytogenetic aberrations and molecular deregulations of pathways regulating senescence, proliferation and differentiation. It has been shown that SKP2, an F-box protein and a component of the ubiquitin protein ligase complex SCFs (SKP1-cullin-F-box), is over-expressed in RMS primary samples and correlates with a dismal outcome. Therefore, we sought here to investigate the regulation of SKP2 and its role in ERMS.
Methods:
We modulated SKP2 expression through silencing, by using a siRNA validated in the literature, and forcing its expression through retroviral infection. In parallel, we investigate the effect of Notch signaling modulation on SKP2 expression.
Results:
SKP2 silencing resulted in cell cycle slowdown in both normal myoblasts and ERMS cells. Down-regulation of Notch1 led to SKP2 reduction while that of Notch3 supported SKP2 expression. Cosilencing SKP2 and Notch3 gave raise to myoblast-like structure formation in ERMS and facilitated myoblasts fusion. Finally, using a SKP2 inhibitor ERMS cell proliferation was completely blocked.
Conclusion:
Altogether, these preliminary experiments suggest that SKP2 could be regulated by Notch signaling in ERMS and that its inhibition hampers tumor cell proliferative capability.
Note: This abstract was not presented at the meeting.
Citation Format: Rossella Rota, Laura Adesso, Beatrice Conti, Roberta Ciarapica, Lavinia Raimondi, Maria De Salvo, Sonia Rodriguez, Nadia Carlesso, Lucio Miele, Franco Locatelli. SKP2 supports cell proliferation and is regulated by Notch signaling in myoblasts and embryonal rhabdomyosarcoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3792. doi:10.1158/1538-7445.AM2015-3792