bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 214: High expression of CKS1B antagonizes MLN4924, a nedd8-activating enzyme inhibitor, that induces myeloma cell growth inhibition through decreased neddylation of SCF complex
Authors: Zhan Fenghuang , Wang He , Zangari Maurizio , Tricot Guido 
Published: August 2012

Abstract
Background: MLN4924 binds to the NEDD8-activating enzyme (NAE), and promotes neddylation of SCF (Skp1-Cul1 / Cdc53-F-box protein) complex resulting in inhibition of proteasomal degradation of several substrates. CKS1B acts as an adaptor of SCF complexes involved in cell cycle progression and DNA damage repair in many cancers, including multiple myeloma (MM). In this study, we investigate the functional role of CKS1B expression on MLN4924 in myeloma and determine whether CKS1B can be used as a potential biomarker for sensitivity to MLN4924 treatment in MM. Methods: Three myeloma cell lines, KMS12, KMS28PE, and OCI-MY5 in which CKS1B was artificially over-expressed (CKS1B-OE) as well as their empty vector (EV) controls were treated with MLN4924 at different concentrations. The IC50 and growth inhibition of cells were analyzed via a fluorencent screeing assay. APC-labeled annexinV and PI were assessed by flow cytometry to detect apoptosis and cell cycle changes. The expression of Cullin-NEDD8 and a series of ubiquitined SCF substrates were analyzed by non-reducing western blot. Results: MLN4924 effectively inhibited cell growth and induced cell apoptosis in both CKS1B-OE and EV MM cells. However, MM cells transfected with EV were more sensitive than those transfected with CKS1B-OE as evidenced by the IC50 values (KMS28PE OE vs. EV 99: 65 nM; KMS12 OE vs. EV 125: 72 nM; and OCI-MY5 OE vs. EV 106:89 nM). The cell viabilities at 100 nM were 49.6% vs. 26.7%, 54.5% vs. 34.2%, and 53.6% vs. 36.8% in CKS1B-OE versus EV KMS28PE, KMS12, and OCI-MY5 cells (P&lt;0.05). Western blots showed that over-expression of CKS1B significantly decreased expression of cullin1, nedd8, and the conjugated complex of cullin-nedd8 in MLN4924 treated cells (100 nM, 24h) compared with EV in all tested three cell lines. We also found that high expression of CKS1B was negatively correlated with SCF substrates including p21, CDT-1, p27 and CDT-1. MLN4924 induced a dose-dependent accumulation of these substrates in all three MM cell lines. Conclusion: High expression of CKS1B induces SCF substrate ubiquitination and degradation in MM cells. The NAE inhibitor MLN4924 induces cell apoptosis through decreased neddylation of SCF complex resulting in increase of p27, p21, CDT-1 and p130. CKS1B can be used as a marker of drug resistance to MLN4924, suggesting that a combination of MLN4924 with other drugs will be necessary to treat myeloma patients with high endogenous expression of CKS1B.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 214. doi:1538-7445.AM2012-214
Abstract 2145: Coupling S100A4 to Rhotekin alters Rho signaling output in breast cancer cells
Authors: Chen Min , Bresnick Anne R. , O'Connor Kathleen L. 
Published: August 2012

Abstract
S100A4 is a calcium binding protein and tumor metastasis associated factor that has been suggested to promote motility and invasiveness of different types of cancer. This migratory promoting effect, in part, is due to the interaction of S100A4 with actin and actin binding proteins, such as myosin IIA. We found that S100A4 interacts with Rho binding domain of Rhotekin (TRBD), one of the Rho effectors, thus suggesting a connection between the Rho and S100A4 pathways. To test whether this interaction is specific, we performed GST pull-down assays using Rho binding domain from different Rho effectors such as Rhotekin, Rhophilin, PKN, ROCK II, and Citron. These results showed that S100A4 specifically interacts with Rho binding domain of Rhotekin but not of other Rho effectors. We further determined that this interaction is direct and calcium-dependant by performing GST-TRBD pull-down assays with purified S100A4 in the presence and absence of calcium. The in vivo interaction of these two proteins was further confirmed by immunoprecipitation of exogenously expressed mutated forms of Rhotekin with endogenous S100A4 from MDA-MB-231 cells. Confocal microscopy showed that Rhotekin and S100A4 co-localize at the edge of membrane ruffles in response to EGF. We demonstrated that S100A4 did not bind TRBD using the same residues as Rho, as determined by using a triple-A mutant of Rhotekin. Interestingly, we found that active Rho, S100A4 and Rhotekin are in a complex by using constitutively active GST-RhoQ63L pull-down assay. To examine the function of this interaction, RNAi was used to suppress Rhotekin and/or S100A4 in MDA-MB-231. F-actin staining showed that suppression of both RTKN and S100A4 leads to the loss of Rho-dependent membrane ruffling in response to EGF stimulation, an increase in contractile F-actin “stress” fibers in the cell body and a reduction in invasive growth in three-dimensional culture. Taken together, we showed that S100A4 specifically and directly interacts with Rhotekin in a calcium-dependent manner. This coupling permits S100A4 to complex with RhoA and switch RhoA function from stress fiber formation to membrane ruffling. Based on the function of this interaction, we propose that interaction of S100A4 and Rhotekin alters the functional output of Rho signaling to confer an invasive phenotype in breast cancer cells.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2145. doi:1538-7445.AM2012-2145
Abstract 2149: Cooperation of Notch and RAS/MAPK pathway leads to poor outcome in breast cancer patients
Authors: Mittal Suruchi , Kumar Rekha V. , Rangarajan Annapoorni 
Published: August 2012

Abstract
Breast cancer is a leading cause of cancer-related deaths in women the world over, particularly in the Western population. However, emerging trends indicate an alarming rise in breast cancer incidences in other parts of the world including India. A major impediment in breast cancer treatment is occurrence of metastasis leading to poor prognosis and survival in certain patients. Therefore understanding the molecular pathways responsible for such phenomenon is critical. Recent studies have implicated aberrant Notch signaling in breast cancers. We undertook an extensive study analysing the expression of the Notch pathway members in breast biopsies of Indian origin. We observed increased expression of several Notch receptors including Notch 1, 2 3, and 4, Notch-ligands including Jagged1, Jagged2, and Delta-like 4, and downstream targets of the Notch pathway Hes1/Hes5 in breast cancer tissues compared to the normal counterpart. Additionally, we detected cleaved (active) Notch1 and Hes1/5 in early precursors of breast cancers - hyperplasia and ductal carcinoma in situ - suggesting that aberrant Notch activation may be an early event in breast cancer progression. In in vitro transformation experiments, we observed that while constitutively active Notch1 alone failed to transform HMLE immortalized breast cells, it synergized with the Ras/MAPK pathway to mediate transformation in vitro. Interestingly, compared to only cleaved Notch positive cases, those positive for both pERK1/2 and Notch showed poor survival, and majority of such cases were triple negative breast cancers. This suggests that in highly aggressive triple negative breast cancers that exhibit poor survival, the Notch and Ras/MAPK pathway cooperation might play a crucial role and thus targeting these two pathways together might offer a novel therapeutic strategy for this aggressive form of cancer.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2149. doi:1538-7445.AM2012-2149
Abstract 2150: The role of SHP2 in HER2+ breast cancer
Authors: Wang Xiaonan 
Published: August 2012

Abstract
Breast cancer is the most common malignancy and the second most common cause of cancer related death in women. HER2+ over-expressing (HER2+) tumors comprise 20% to 25% of all cases and are associated with a poor prognosis. The discovery of HER2 monoclonal antibody-based therapeutics has greatly improved patient prognosis. However, patients suffer relapse and de novo resistance. Thus it is important to determine additional therapeutic targets in HER2+ breast cancer that might be used in combination with current therapies to improve patient survival. SHP2 (PTPN11) is a non-receptor protein-tyrosine phosphatase (PTP) that contains two SH2 domains at its N-terminus, a central PTP domain and a C-terminal proline-rich tail. Previous studies suggest that Shp2 is required for Ras/Erk signaling downstream of most growth factor receptors and integrins. Heterozygous germ-line PTPN11 mutations cause Noonan Syndrome and LEOPARD syndrome, which are associated with leukemia and cancer predisposition. Somatic PTPN11 mutations cause juvenile myelomonocytic leukemia (JMML) and several other neoplasms. We have discovered that Shp2 is required in Neu-mediated tumorigenesis in the MMTV-NIC mouse model; furthermore, SHP2-depleted human HER2+ BT-474 has defective tumorigenesis in nude mice. SHP2 is required in anchorage-independent growth in 4 HER2+ breast cancer cell lines, though its effect on growth on plastics appears minimal. I hypothesize that SHP2 is required for HER2+ breast tumor initiation and maintenance. I further hypothesize that SHP2 functions through specific substrates/interacting proteins in HER2+ breast cancer cells, possibly molecules that are involved in anchorage-independent proliferation.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2150. doi:1538-7445.AM2012-2150
Abstract 2151: Activation of NF-kB and MAP kinases by TNF Family Receptors is regulated by cellular IAPs
Authors: Varfolomeev Evgeny , Goncharov Tatiana , Maecker Heather , Zobel Kerry , Komuves Laszlo , Deshayes Kurt , Vucic Domagoj 
Published: August 2012

Abstract
Activation of NF-kB, JNK and p38 MAPK signaling pathways is innermost activity of TNF receptor protein signaling complexes that is important for proper function of the immune system. However, excessive activation of these signaling pathways may result in tumor development and progression. Therefore, elucidation of the detailed molecular mechanisms of TNF receptor signaling should gain advantage in our understanding of the tumor biology and invention of the novel anticancer therapies. The formation of TNF receptor complexes, as well structural and functional associations between different signaling molecules is regulated by ubiquitination in TRAF-dependent fashion. TNF receptors employ several proteins possessing ubiquitin E3 ligase activities including cellular Inhibitor of Apoptosis, c-IAP1 and c-IAP2 proteins. We demonstrate that c-IAPs are required for canonical NF-kB and MAPK activation by TNF receptors. By regulating the recruitment of Nemo, IKK2 and HOIP to TNFR signaling complexes c-IAPs promote induction of gene expression by TNF ligands. We also found that TNF receptors that stimulate the noncanonical NF-kB pathway trigger c-IAPs, TRAF2 and TRAF3 intracellular translocation followed by their proteasomal and lysosomal degradation. Finally, we establish that BR3-induced cytosolic depletion of TRAF3 results in noncanonical NF-κB activation.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2151. doi:1538-7445.AM2012-2151
Abstract 2156: Preclinical combinations of vemurafenib, a selective BRAF inhibitor, with other targeted therapies in BRAFV600E colorectal cancer models
Authors: Yang Hong , Higgins Brian , Kolinsky Kenneth , Li Jiakui , Margolis Richard , Go Zenaida , Railkar Aruna , Packman Kathryn , Bollag Gideon , Su Fei 
Published: August 2012

Abstract
Mutations in BRAF at codon 600 promote catalytic activity and are associated with 8% of all human (solid) tumors, including about 10% of colorectal cancers (CRCs). Vemurafenib (RG7204, PLX4032) is a first-in-class, BRAF-specific small molecule inhibitor that dose-dependently inhibits tumor growth in BRAFV600E CRC xenografts. Despite these encouraging preclinical findings, unlike the remarkable responses observed in melanoma, single agent vemurafenib in a Phase I extension trial of 21 patients with previously treated metastatic CRC resulted in a modest 5% response rate. We therefore explored a range of combinations of vemurafenib with different novel targeted therapies including a MEK inhibitor, an AKT inhibitor, a PI3K inhibitor, an mTOR/PI3K dual inhibitor and an EGFR inhibitor in BRAFV600E CRC cell lines. The consequences of these combinations on proliferation were analyzed by MTT assay and the combined effect was determined by combination index (CI) calculated using CalcuSyn software. Western analysis and Annexin V staining were utilized to evaluate combination effects on downstream signaling events and apoptosis induction. Optimized doses of both vemurafenib and a MEK inhibitor were tested as single agents and in combination in CRC xenograft models in nude mice. Synergistic anti-proliferative effects were observed with combinations of vemurafenib and other targeted therapies in the BRAFV600E positive CRC cell lines tested. More effective signaling inhibition and apoptosis induction were observed with the combinations than either agent alone. Combining vemurafenib with a MEKi delivered greater anti-tumor activity and increased life span of animals in the LS411N CRC xenograft model. In a BRAF-mutant CRC xenograft model with inherent resistance to vemurafenib (RKO), tumor growth inhibition by vemurafenib was enhanced by combining with an AKT inhibitor. These in vitro and in vivo data suggest that the administration of vemurafenib in combination with novel targeted therapies may be effective in delivering enhanced and sustained clinical antitumor efficacy in colorectal cancers harboring the BRAFV600E mutation.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2156. doi:1538-7445.AM2012-2156
Abstract 2158: RAF signaling and SHOC2 mediate mutant NRAS acquired resistance to RAF inhibitors in melanoma
Authors: Kugel Curtis H. 
Published: August 2012

Abstract
RAS signaling through extracellular signal-regulated kinase 1/2 (ERK1/2)/mitogen-activated kinase (MAPK) pathway is critical for normal cellular homeostasis and is frequently aberrantly regulated in cancerous cells. Although often depicted as a linear sequence of RAS-RAF-MEK-ERK1/2, this pathway is also regulated by expression of multiple isoforms of proteins at each level, scaffold proteins that enhance pathway activation, and negative feedback mechanisms. Some of these factors may also impact on the response of the pathway to pharmacological inhibitors. To test this notion, we analyzed resistance to the RAF inhibitor, PLX4720, using mutant BRAF melanoma cell models. In a screen to isolate cells displaying resistance to the inhibitory effects of PLX4720, we observed a subset of cells harboring an acquired mutation in NRAS. In parental cells, expression of mutant NRAS was sufficient to prevent PLX4720-mediated inhibition of ERK1/2 signaling, entry into S phase and susceptibility to apoptosis in mutant BRAF cells. Effects of mutant NRAS were associated with the maintenance of RAF binding. Analysis of isolated clones of RAF inhibitor-resistant mutant BRAF cells demonstrated that re-activation of the ERK1/2 pathway in the presence of PLX4720 was dependent on NRAS, BRAF, CRAF, and the RAS-RAF scaffold protein, SHOC2/Sur-8. Depletion of SHOC2 also rendered resistant cells susceptible to PLX4720-mediated apoptosis in 3D collagen. Together, these data demonstrate the role of RAF isoforms and a RAS-RAF scaffold protein in the acquired resistance to RAF inhibitors induced by secondary mutations in NRAS.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2158. doi:1538-7445.AM2012-2158
Abstract 2160: Regulation of DHX33 during oncogenic stress and its crucial role in Ras-initiated tumor formation
Authors: Zhang Yandong , Weber Jason D. 
Published: August 2012

Abstract
Previously we found that DHX33 is pivotal for RNA polymerase I transcription, changes in DHX33 levels have a dramatic impact on RNA polymerase I activity. In this report, we explore the regulation of DHX33 protein levels by ARF/p53 pathway and Ras signaling. In wild type primary fibroblasts, Ras V12 infection induced a transient increase in DHX33 protein level as well as rRNA transcriptional rate which was eventually overcome by suppression from ARF/p53 pathway. ARF/p53 dependent reduction of DHX33 occurred at the translational level, while Ras activation induced DHX33 levels both at the level of transcription and translation. The induction of DHX33 by Ras activation is sensitive to inhibitors of PI3K, mTOR as well as MAPK. Induction of DHX33 by Ras V12 is pivotal for enhanced rDNA transcription, enhanced protein translation, and thus, the oncogenecity of Ras V12, as DHX33 knockdown abolished the increase in rRNA transcription and protein translation, and completely inhibited the tumorigenecity of Ras V12 both in semisolid agar and xenografts. Our results implicate that DHX33 level could be an important factor to adjust rDNA transcriptional rate in response to ARF induction and Ras activation. Most importantly, we identified DHX33 as a novel downstream target of Ras signaling to regulate rRNA transcription and pointed toward its pivotal role in Ras-initiated tumor formation and therapeutic value to treat Ras mutated cancer patients.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2160. doi:1538-7445.AM2012-2160
Abstract 2166: In silico identification and biological evaluation of potent small molecule inhibitors targeting GAB1 pleckstrin homology domain
Authors: Dumas Sabrina , Du-Cuny Lei , Moses Sylvestor , Song Zuohe , Zhang Shuxing , Meuillet Emmanuelle J 
Published: August 2012

Abstract
The Grb2-associated binder-1 (GAB1) over-expressed in many cancers represents a novel therapeutic target that integrates signals from different systems such as MET and PI3K/Akt pathways. It mediates processes involved in tumor progression and metastasis. In this study we have identified novel inhibitors targeting the pleckstrin homology (PH) domain of GAB1 for cancer treatment. To this end, a homology model of GAB1 PH domain was constructed, followed by structural refinement using molecular dynamics. The resulting structure was applied to high-throughput virtual screening of 5 million compounds and 19 hits were selected for experimental evaluation. We found that 6 compounds bound to the PH domain of GAB1 as measured by surface plasmon resonance spectroscopy, with a KD. Out of these 6 hits, all of them inhibited the HGF-I induced phosphorylation of GAB1 Tyr627 in T47D and inhibited T47D and MDA-MB-231 breast cancer cell lines proliferation. Three of them exhibited selective binding to GAB1 PH domain as compared to the PH domain of IRS-1 and AKT. This demonstrates for the first time the identification of novel GAB1 PH domain inhibitors which may be used for targeted breast cancer therapy.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2166. doi:1538-7445.AM2012-2166
Abstract 217: Modulation of Hsp90 chaperone activity by hypoxic condition: Hypoxia stimulates ARD1-mediated Hsp90 post-translational modification
Authors: Woo Jong Kyu , Lee Ho-Young 
Published: August 2012

Abstract
Arrest defective-1 protein (ARD1, also known Naa10p) is an N-acetyltransferase known to be involved in cell cycle control. Several reports have implicated ARD1 in regulation of cell proliferation and apoptosis in mammalian cells. Although a potential role for ARD1 in controlling cell proliferation and apoptosis has been identified, little is known about the relevance of ARD1 to cancer development. Heat Shock Protein 90 (Hsp90), an essential molecular chaperone in eukaryotic cells, maintains the functional conformation of a subset of proteins that are typically key components of multiple regulatory and signaling networks mediating cancer cell proliferation, survival and metastasis. Reversible acetylation has been implicated as a regulatory post-translational modification of Hsp90. Although an acetyltransferase responsible for acetylating Hsp90 has yet to be identified, several groups recently identified Histone deacetylase 6 (HDAC6) as an one of the Hsp90 deacetylase. This study, we show that hypoxia leads to increased Hsp90 acetylation via ARD1 binding to Hsp90 and disrupted interaction between Hsp90 and client proteins and co-chaperone proteins. We found that treatment with the HDAC inhibitor trichostatin A (TSA) or sodium butyrate (NaB) enhanced Hsp90 acetylation and led to the dissociation of Hsp90 and client protein Hif-1a. To gain further insight into protein acetylation in the cytoplasm, we searched cellular targets for Hypoxia. By using an immunoprecipitation approach, we identified ARD1 as a prominent Hsp90 interacting partner. Transfection of ARD1 leads to Hsp90 hyperacetylation, its dissociation from an essential co-chaperone proteins and a loss of chaperone activity. Transfected ARD1 and Hsp90 can be abundantly and specifically co-immunoprecipitated under hypoxia condition. Those interactions prevented the formation of the Hsp90 chaperon complex, resulting in reduced chaperone function of Hsp90. We suggest that ARD1 functions as a tumor suppressor by disrupting the function of Hsp90, and thus inactivating of PI3K/Akt pathway and Hif-1a in cancer cells under hypoxic condition. We conclude that a coordinated interaction between Hsp90 and ARD1 under hypoxic condition may be an important mechanism for hypoxic cell signal to homeostasis.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 217. doi:1538-7445.AM2012-217