bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 4966: Identification of deubiquitinating enzyme USP19 as a regulator of EWS/FLI1 protein turnover in Ewing sarcoma
Authors: Gierisch Maria E. , Lopez-Garcia Laura A. , Pfistner Franziska , Niggli Felix K. , Schaefer Beat W. 
Published: August 2015

Abstract
Ewing sarcoma belongs to the family of pediatric tumors which arise most commonly in bone. The majority of Ewing sarcoma is characterized by a balanced translocation between chromosomes 11 and 22 which encodes for the uniquely expressed fusion protein EWS/FLI1. Tumor cells are crucially dependent on expression of the fusion protein. Protein degradation is an important and highly regulated process in all cells and novel insights are beginning to be applied for cancer therapy. We aim to investigate the mechanism of turnover with the goal to diminish EWS/FLI1 protein and thereby identify novel targets for Ewing sarcoma treatment.
Here, we show first that EWS/FLI1 protein stabilizes upon proteasome inhibition. Co-immunoprecipitation of EWS/FLI1 with ubiquitin shows a characteristic ubiquitination smear indicating that EWS/FLI1 is ubiquitinated and a substrate of the ubiquitin-proteasome system. We characterized the turnover itself as rather slow. Interestingly, the half-life time of the fusion protein is increased by four-fold compared to the full length protein FLI1. This increased stability possibly contributes to the oncogenic and resistant features of the fusion protein.
To identify a deubiquitinating enzyme capable of regulating EWS/FLI1 turnover, we selected 20 deubiquitinating enzymes based on their expression in Ewing cell lines and tumors in-silico. Then, we established a screening approach directly measuring EWS/FLI1 protein levels as a read-out by an ELISA-like assay, allowing us to monitor the amount of 3x flag-tagged EWS/FLI1 protein. After transient knocked down of the 20 candidates, the screening revealed ubiquitin specific protease 19 (USP19) as a promising candidate. Depletion of USP19 via siRNA or shRNA was capable to diminish endogenous EWS/FLI1 protein level which led to modulation of its target gene levels. Vice versa, USP19 overexpression stabilized EWS/FLI1 protein level by twofold. Most importantly, stable knockdown of USP19 in Ewing cell lines led to a 40% reduction of cell growth and proliferation. Currently, we further characterize the influence of USP19 on EWS/FLI1 turnover and Ewing cell viability in vivo to identify novel possibilities for therapeutic interventions.
Citation Format: Maria E. Gierisch, Laura A. Lopez-Garcia, Franziska Pfistner, Felix K. Niggli, Beat W. Schaefer. Identification of deubiquitinating enzyme USP19 as a regulator of EWS/FLI1 protein turnover in Ewing sarcoma. [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 4966. doi:10.1158/1538-7445.AM2015-4966
Abstract 4970: USP15 regulates SMURF2 kinetics through C-lobe mediated deubiquitination
Authors: Eichhorn Pieter J.A. , Iyengar Prasanna , Jaynes Patrick , Verma Chandra 
Published: August 2015

Abstract
Transforming growth factor-β (TGFβ) is a multifunctional cytokine that acts as a tumour suppressor in normal cells and as an oncogene in advanced tumour cells. In the later scenario, TGFβ signaling enhances pro-invasive and pro-metastatic properties of the cancer cell. Ubiquitin modification of the TGF-β pathway components is emerging as a key mechanism of TGF-β pathway regulation. To limit TGF-β responses, TGF-β signaling is regulated through a negative feedback loop whereby the E3 ligase SMURF2 targets the TGF-β receptor (TβR) complex for ubiquitin-mediated degradation. Counteracting this process, a number of deubiquitinating (DUBs) enzymes have recently been identified that deubiquitinate and stabilize the TβR. However the precise mechanism by which these DUBs act on TβR function remains poorly defined. Here, we demonstrate that apart from targeting the TBR complex directly USP15 also deubiquitinates SMURF2 resulting in enhanced TβR stability and downstream pathway activation. Through proteomic analysis, we show that USP15 modulates the ubiquitination of Lys734, a residue required for SMURF2 catalytic activity. Our results show that SMURF2 is a critical target of USP15 in the TGF-β pathway and may also explain how USP15 and SMURF2 target multiple complementary protein complexes in other pathways.
Citation Format: Pieter J.A. Eichhorn, Prasanna Iyengar, Patrick Jaynes, Chandra Verma. USP15 regulates SMURF2 kinetics through C-lobe mediated deubiquitination. [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 4970. doi:10.1158/1538-7445.AM2015-4970
Abstract 4971: Detection of receptor and non receptor tyrosine kinases in the culture filtrates of astrocytes and cancer cells
Authors: Gogineni Venkateswara Rao 
Published: August 2015

Abstract
As demonstrated in our previous work, meningioma cells shed their membrane receptors and these receptors function in a cell-free environment. The purpose of this study was to determine if receptor and non-receptor kinases were similarly being released in different cancers. Using antibody arrays, cell culture filtrates from glioma and prostate cancer cell lines were assessed to determine if solubilized receptors and kinases were present. Supernatants from cells treated with Brefeldin-A were analyzed similarly. Further, culture filtrates concentrated by ultrafiltration were subjected to luminescence based kinase assays and western blotting to assess the active forms. Cell viability was measured with Trypan blue staining in all the experiments. Our results demonstrate that an array of receptors are solubilized into culture filtrates of brain and prostate cancer cell lines within the first 24 hours. Simultaneously, soluble receptors in the culture filtrates of astrocytes within 48 hours of culture were also detected. Compared to astrocytes, cancer cells showed elevated levels of receptors and kinases released at 48 hours. As many as 15 receptor or non-receptor tyrosine kinases including Src family of kinases were found in the culture filtrates of the brain and prostate cancer cell lines. Treatment with Brefeldin-A inhibited the release of receptors and kinases partially, but markedly, within first 24 hours suggesting a secretory pathway for their release. Additionally, phosphorylation of tyrosine kinases was detected in the western blots within 24 hours. Kinase assays further confirmed active nature of the extracellular kinases, particularly, when checked for the active form of Lyn kinase in the culture filtrates, phosphorylation on Tyrosine-507 was detected along with the total forms. Cell viability assays on the cultured cells revealed more than 98% viability, thus eliminating the possibility of the release of detected kinases from dead cells. In light of this study, we propose a new niche for solubilized receptor and tyrosine kinase functioning that might have a role in intercellular signaling in cell-free conditions both in disease and physiological statuses.
Note: This abstract was not presented at the meeting.
Citation Format: Venkateswara Rao Gogineni. Detection of receptor and non receptor tyrosine kinases in the culture filtrates of astrocytes and cancer 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 4971. doi:10.1158/1538-7445.AM2015-4971
Abstract 4985: Notch1 as a key mediator in promoting advanced castration-resistant prostate cancer
Authors: Stoyanova Tanya , Faltermeier Claire , Smith Bryan , Goldstein Andrew , Zhang Xi , Drake Justin , Lee John , Orellana Sandra , Blum Steven , Cheng Donghui , Pienta Kenneth , Huang Jiaoti , Witte Owen 
Published: August 2015

Abstract
The first line of treatment for men with advanced prostate cancers is androgen deprivation therapy. However, the disease commonly relapses in its lethal metastatic form referred to as castration-resistant prostate cancer (CRPC). CRPC is the primary cause of prostate cancer specific mortality in men. Current therapies including chemotherapeutic agents improve median overall survival by only few months. The mechanisms that distinguish clinically localized indolent tumors from lethal CRPC are unclear. Here we demonstrate that ectopic expression of Notch1 promotes progression to poorly differentiated carcinoma when combined with pathways that are altered in advanced disease but are insufficient to drive aggressive prostate cancer alone. Notch1 driven tumors are resistant to androgen deprivation. Transcriptional profiling reveals that these tumors display features of epithelial to mesenchymal transition, a morphological change associated with tumor aggressiveness and metastasis. Our study provides the first functional evidence that Notch1 signaling axis is a key mediator in promoting advanced prostate cancer and may represent a new therapeutic target for the advanced disease.
Note: This abstract was not presented at the meeting.
Citation Format: Tanya Stoyanova, Claire Faltermeier, Bryan Smith, Andrew Goldstein, Xi Zhang, Justin Drake, John Lee, Sandra Orellana, Steven Blum, Donghui Cheng, Kenneth Pienta, Jiaoti Huang, Owen Witte. Notch1 as a key mediator in promoting advanced castration-resistant prostate 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 4985. doi:10.1158/1538-7445.AM2015-4985
Abstract 4989: Cannabinoid receptor 2 and C-X-C chemokine receptor 4 interact to abrogate CXCL12-mediated cellular response
Authors: Coke Christopher , Johnson Ahriea , Jones Kia , Hinton Cimona 
Published: August 2015

Abstract
The expression of C-X-C Chemokine Receptor 4 (CXCR4) has been correlated with increased metastatic potential of cancer cells. CXCR4 increases tumor malignancy by encouraging tumors cells to migrate to distal organs expressing its cognate ligand, CXCL12, facilitating metastasis. Thus, targeting the CXCR4/CXCL12 signaling axis provides a good strategy to inhibit the metastatic spread of tumor cells and slow cancer progression. Recent studies suggest that cannabis may have anti-proliferative as well as anti-metastatic properties, though a biochemical mechanism describing how this occurs has yet to be discovered. Our lab has confirmed that an interaction between agonist-bound CXCR4 and agonist-bound Cannabinoid Receptor 2 (CB2) can decrease cancer cell migration. Simultaneous treatment of the breast cancer cell line, MDA-MB-231 with CXCL12 and AM1241, a synthetic ligand for CB2, desensitized the intrinsic cellular response to migrate toward areas of high CXCL12 concentration. Furthermore, through co-immunoprecipitation, we determined that there was increased interaction between the two receptors with co-stimulation. When CXCR4 and CB2 were activated simultaneously with various agonists, decreases in migration were observed, confirming that the regulatory activity was receptor-based, not agonist-based. Moreover, when cells were treated with the CB2 antagonist (AM630) and CXCL12 simultaneously, the decrease in migration was no longer seen, as CXCL12 was able to induce cell movement. In order to determine whether receptors were activated in response to simultaneous stimulation, calcium mobilization assays were performed and results showed that transiently activated calcium levels were significantly lower in response to simultaneous treated cells when compared to cells treat with their individual ligands. Therefore, we propose that the interaction of CB2 with CXCR4 may play a role in inhibiting the cells response to CXCL12, leading to a loss in metastatic potential and presenting a new mechanism for regulating oncogenic signaling.
Citation Format: Christopher Coke, Ahriea Johnson, Kia Jones, Cimona Hinton. Cannabinoid receptor 2 and C-X-C chemokine receptor 4 interact to abrogate CXCL12-mediated cellular response. [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 4989. doi:10.1158/1538-7445.AM2015-4989
Abstract 499: Characterization of the cell death mechanism after silencing of PAX3-FOXO1 in alveolar rhabdomyosarcoma using a CRISPR-Cas mediated knockout approach
Authors: Wachtel Marco , Niggli Felix , Schäfer Beat 
Published: August 2015

Abstract
Chromosomal translocations leading to the generation of PAX-FOXO1 fusion oncogenes are found in about 80 percent of all alveolar Rhabdomyosarcoma (aRMS). Recent whole genome sequencing studies revealed that apart from these translocations mutation frequency is generally very low in aRMS, with no other genetic changes detected in some cases. aRMS tumor cells depend on the fusion protein and exhibit cell cycle arrest or undergo cell death upon blocking of its activity. Taken together this strongly suggests that the PAX-FOXO1 fusion represents the tumor initiating event and that it remains the most important tumorigenic factor for aRMS maintenance at later tumor stages.
However, the molecular mechanisms involved in tumorigenesis downstream of PAX3-FOXO1 are only partially understood yet, including the ones involved in oncogene addiction. We therefore aimed to further characterize the molecular events leading to cell death after silencing of PAX3-FOXO1. Towards this aim, we used an inducible shRNA system to silence PAX3-FOXO1 in different aRMS cell lines. Reduction of PAX3-FOXO1 below a threshold of about 20 percent of its basal level efficiently induced Caspase-dependent cell death. CRISPR-Cas mediated knock-out of individual members of the apoptotic cascade was then used to further characterize the involved apoptotic mechanism. BH3-only proteins including Bim were found as relevant sensors detecting cellular stress after silencing of PAX3-FOXO1.
This data suggests that combined interference with PAX-FOXO1 activity and anti-apoptotic Bcl-2 family members might accelerate tumor cell death.
Citation Format: Marco Wachtel, Felix Niggli, Beat Schäfer. Characterization of the cell death mechanism after silencing of PAX3-FOXO1 in alveolar rhabdomyosarcoma using a CRISPR-Cas mediated knockout approach. [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 499. doi:10.1158/1538-7445.AM2015-499
Abstract 5: Mcl-1-mediated resistance to ABT-263 is combated by mTOR inhibition in luminal breast cancers
Authors: Williams Michelle M. , Lee Linus , Sanchez Violeta , Morrison Meghan M. , Hicks Donna , Cook Rebecca S. 
Published: August 2015

Abstract
We found that 8.1% of luminal breast cancer cases curated by The Cancer Genome Atlas (TCGA), harbor gene amplification of anti-apoptotic Bcl-2 family members, warranting further study of anti-apoptotic Bcl-2 family proteins (A1, Bcl-2, Bcl-xL, Bcl-w and Mcl-1) in luminal breast cancers. A complex balance of pro- and anti-apoptotic Bcl-2 proteins guides activation versus repression of the intrinsic apoptotic pathway, with overexpression of anti-apoptotic factors tipping the balance towards cell survival. This mechanism is commonly used by cancers to evade apoptosis.
We used the BH3-mimetic ABT-263 to inhibit Bcl-2, Bcl-xL and Bcl-w in a panel of human luminal breast cancer lines, causing only modest apoptosis in monolayer and growth inhibition in three-dimensional (3D) matrix. Expression and activity of Mcl-1, another anti-apoptotic Bcl-2 family member, was rapidly upregulated in response to ABT-263 through increased cap-dependent MCL1 translation. Mcl-1 knock-down decreased tumor cell growth and improved ABT-263-mediated tumor cell killing. Inhibition of cap-dependent translation using the mTOR inhibitor RAD001/everolimus or the EIF4 complex inhibitor 4E1RCat blocked Mcl-1 induction in ABT-263 treated cells, enhancing apoptosis and growth inhibition. In vivo, single agent ABT-263 was ineffective at reducing tumor growth in xenografted human breast cancers and in transgenic WAP-Myc luminal mammary tumors. However, RAD001 decreased Mcl-1 levels and decreased WAP-Myc tumor growth by 40%. These results demonstrate that heightened cap-dependent translation of Mcl-1 prevents therapeutically induced tumor cell killing in ABT-263 treated luminal tumors, highlighting the importance of Mcl-1 regulation in therapeutic resistance, and identifying Mcl-1 as a potential therapeutic target in luminal breast cancers. These studies suggest that targeted inhibition of Mcl-1 alone or in combination with other Bcl-2 family inhibitors will enhance tumor cell killing in luminal breast cancers.
Citation Format: Michelle M. Williams, Linus Lee, Violeta Sanchez, Meghan M. Morrison, Donna Hicks, Rebecca S. Cook. Mcl-1-mediated resistance to ABT-263 is combated by mTOR inhibition in luminal breast cancers. [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 5. doi:10.1158/1538-7445.AM2015-5
Abstract 5002: Abstract Submission
Authors: Acharya Swati , Petersen Kira Y.D , Golubkov Vladislav , Kwong Mandy , Adams Christopher M. , Jackson Peter K. , Lewis David B. 
Published: August 2015

Abstract
Protein tyrosine kinase 7 (PTK7), a catalytically inactive receptor tyrosine kinase (RTK) that is highly expressed by T-lineage cells during intrathymic development, is a novel marker for human CD4+ recent thymic emigrants (RTEs), and is also highly expressed on some T-lineage thymomas, e.g., Jurkat cells as well as inprimary T-Acute Lymphoblastic leukemia. The function of PTK7 in normal human T-cell development and in oncogenesis remains unclear. Here, using RNAi-mediated gene silencing in T-lineage tumor cells, primary human peripheral T-cells, and thymocytes, we found that targeting PTK7 consistently decreased cell survival by augmenting caspase-3 activation of apoptosis. The PTK7 knockdown also decreased AKT phosphorylation and PI3 kinase activity, suggesting an essential role for PTK7 in survival of RTEs and developing thymocytes involving the PI3K/AKT pathway. Using mass spectrometry we identified insulin-like growth factor-1 (IGF-1) receptor as an active kinase partner of PTK7. This interaction was biologically relevant in that PTK7 downregulation also reduced IGF-1R-dependent survival signals in T-lineage cells. As enhanced IGF-1-dependent signaling is a frequent event in oncogenesis, the intersection of PTK7 with the IGF-1 signaling pathway suggests the potential of PTK7-directed therapy of T-lineage tumors.
Citation Format: Swati Acharya, Kira Y.D Petersen, Vladislav Golubkov, Mandy Kwong, Christopher M. Adams, Peter K. Jackson, David B. Lewis. Abstract Submission. [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 5002. doi:10.1158/1538-7445.AM2015-5002
Abstract 5004: Expression profiling of receptor tyrosine kinases in high-grade neuroendocrine carcinoma of the lung: A comparative analysis with adenocarcinoma and squamous cell carcinoma
Authors: Matsumura Yuki , Umemura Shigeki , Ishii Genichiro , Tsuta Koji , Mastsumoto Shingo , Aokage Keiju , Hishida Tomoyuki , Yoshida Junji , Ohe Yuichiro , Suzuki Hiroyuki , Ochiai Atsushi , Goto Koichi , Nagai Kanji , Tsuchihara Katsuya 
Published: August 2015

Abstract
Background:
As the comprehensive genomic analysis of small cell lung cancer (SCLC) progresses, novel treatments for this disease need to be explored. With attention to the direct connection between the receptor tyrosine kinases (RTKs) of tumor cells and the pharmacological effects of specific inhibitors, we systematically assessed the RTK expressions of high-grade neuroendocrine carcinomas of the lung (HGNEC), including SCLC and large cell neuroendocrine carcinoma (LCNEC).
Patients and Methods:
Fifty-one LCNEC and 61 SCLC patients who underwent surgical resection were enrolled in this research. As a control group, 202 patients with adenocarcinomas (ADCs) and 122 patients with squamous cell carcinomas (SQCCs) were also analyzed. Using immunohistochemical staining (IHC), we stained all tumors with antibodies for 10 RTKs; c-Kit, EGFR, IGF1R, KDR, ERBB2, FGFR1, c-Met, ALK, RET and ROS1. We scored the expression of these RTKs for all enrolled tumors, and compared them according to the histological types.
Results:
The LCNEC and SCLC patients exhibited similar clinicopathological characteristics. The IHC scores for each RTK were almost equivalent between the LCNEC and SCLC groups, but they were significantly different from those of the ADC or SQCC groups. Especially, c-Kit was the only RTK that was remarkably expressed in both LCNECs and SCLCs. On the other hand, about 20% of the HGNEC tumors exhibited strongly positive RTK expression, and this rate was similar to those for the ADC and SQCC tumors. Intriguingly, strongly positive RTKs were almost mutually exclusive in individual tumors.
Conclusions:
Compared with ADC or SQCC, LCNEC and SCLC had similar expression profiles for the major RTKs. The exclusive c-Kit positivity observed among HGNECs suggested that c-Kit might be a distinctive RTK in HGNEC. These HGNECs which have strongly positive RTKs could be the targets of personalized therapies.
Citation Format: Yuki Matsumura, Shigeki Umemura, Genichiro Ishii, Koji Tsuta, Shingo Mastsumoto, Keiju Aokage, Tomoyuki Hishida, Junji Yoshida, Yuichiro Ohe, Hiroyuki Suzuki, Atsushi Ochiai, Koichi Goto, Kanji Nagai, Katsuya Tsuchihara. Expression profiling of receptor tyrosine kinases in high-grade neuroendocrine carcinoma of the lung: A comparative analysis with adenocarcinoma and squamous cell carcinoma. [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 5004. doi:10.1158/1538-7445.AM2015-5004