bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 5021: Temozolomide-induced conversion of glioma cells into glioma “stem-like” cells with enhanced invasion properties.
Authors: Ahmed Atique U. , Auffinger Brenda , Tobias Alex , Thaci Bart , Han Yu , Lesniak Maciej S. 
Published: August 2014

Abstract
Glioblastoma multiforme patients present a poor prognosis due to therapeutic resistance and tumor recurrence after surgical resection. It has been suggested that gliomas are driven by a rare subset of tumor cells, known as cancer stem cells (CSCs). These tumor-initiating cells are considered to be responsible for sustaining long-term tumor growth and disease recurrence. Today, two popular hypotheses try to explain the origin of CSCs: one postulates that CSCs represent an adult stem cell population with tumorigenic alterations, while the second argues that CSCs were once differentiated tumor cells that have re-initiated a self-renewal program. In this study, we first show that exposure to the therapeutic dose of 5 μM (the peak concentration in patient's cerebral spinal fluid) or 50 μM (the concentration in patient's blood) of temozolamide (TMZ), the most commonly used alkylating agent to treat GBM patients, consistently increase the CSC pool over time both in vitro and in vivo. Second, lineage-tracing analysis of genetically tagged glioma cells suggests that TMZ induces a phenotypic shift in the non-CSC population to mimic that of CSCs. These newly formed CSC-like cells co-express markers of pluripotency and stemness (CD133, CD15, Sox-2, Oct-4 and Nestin), a classical characteristic of CSCs. We further show that intracranial implantation of TMZ-treated non-CSC cells in athymic nude mice result in more efficient grafting (100% grafting as compared to 60% for DMSO treated control group). Moreover, these TMZ-treated non-CSC xenografts demonstrate extremely invasive characteristics, which is similar to the CSC enriched xenografts. In addition, they express elevated levels of HIF2α, a critical factor for maintaining the CSC pool. These findings strongly corroborate that chemotherapy-induced selection pressure can facilitate a CSC specific ‘niche’, which may provide the necessary signals to induce an interconversion between differentiated tumor cells and cancer “stem like” cells, leading to a more infiltrative glioma phenotype thereby resulting in therapeutic relapse and may frustrate our attempts to develop effective anti-glioma therapy.
Citation Format: Atique U. Ahmed, Brenda Auffinger, Alex Tobias, Bart Thaci, Yu Han, Maciej S. Lesniak. Temozolomide-induced conversion of glioma cells into glioma “stem-like” cells with enhanced invasion properties. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5021. doi:10.1158/1538-7445.AM2013-5021
Abstract 5033: Modeling Ewing's sarcoma and tolerance of EWS-FLI1 with neural crest stem cells.
Authors: Mosher Jack T. , Chen Victor S. , Lawlor Elizabeth R. 
Published: August 2014

Abstract
Ewing's sarcoma (ES) is a highly malignant bone and soft tissue tumor that primarily affects children and young adults. These tumors are characterized by chromosomal translocations, most commonly t(11;22)(q24;q12), which generates the EWS-FLI1 fusion oncogene. Despite its oncogenic potential, the fusion protein induces cell cycle arrest or apoptosis in most non-transformed cells unless mutations in tumor suppressors such as p16 are also present. However, only a minority of patients (∼25%) have such mutations at diagnosis, suggesting other mechanisms for cellular tolerance must be present in the cell of origin. Currently, the cell of origin of these tumors is controversial, with data supporting both a mesenchymal and/or neural crest origin. To assess the potential to model ES using mouse neural crest stem cells (NCSCs) and elucidate the mechanism(s) of EWS-FLI1 tolerance, primary fetal and adult mouse NCSCs were transduced with a V5-tagged EWS-FLI1 2a eGFP construct. Both wild-type fetal and postnatal NCSCs tolerated EWS-FLI1 expression, with 40-60% of the stem cell-derived neurospheres positive for GFP. There was no difference in neurosphere forming ability between cells infected with EWS-FLI1 or an empty vector, suggesting EWS-FLI1 expression was not toxic to these cells. EWS-FLI1 expression was maintained as the stem cells self-renewed, with GFP-positive primary neurospheres giving rise to GFP-positive secondary and tertiary neurospheres but there was no difference in the frequency of GFP-positive and -negative secondary neurospheres. EWS-FLI1 expression was confirmed by quantitative PCR and the V5 tag was localized to the nucleus by immunocytochemistry, consistent with transcription factor function. EWS-FLI1-mediated gene expression analysis is currently ongoing. Interestingly, the tolerance of EWS-FLI1 was dramatically reduced in Bmi-1 deficient NCSCs. Bmi-1 is known to function cooperatively with multiple other oncogenes to mediate transformation but its role in tolerance has not been studied. In the absence of Bmi-1 only 8% of the fetal neurospheres were positive for GFP, a large decrease compared to 40% of the wild-type neurospheres. Taken together, these data are consistent with a neural crest origin for ES and demonstrate a critical role for Bmi-1-mediated tolerance to EWS-FLI1. Work is ongoing to determine whether EWS-FLI1 can transform these cells and to assess the full utility of this novel system to model ES and genetically assess important regulators of EWS-FLI1 function.
Citation Format: Jack T. Mosher, Victor S. Chen, Elizabeth R. Lawlor. Modeling Ewing's sarcoma and tolerance of EWS-FLI1 with neural crest stem cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5033. doi:10.1158/1538-7445.AM2013-5033
Abstract 5038: Probing network fragilities in neuroblastoma by synergistic drug combinations.
Authors: Radic Branka , Rix Uwe , Kubicek Stefan , Superti-Furga Giulio 
Published: August 2014

Abstract
Neuroblastoma is the most common tumor in infants younger than 1 year of age and one of the most common solid tumors in childhood. The disease is highly variable: while spontaneous tumor regression occurs more often than in any other cancer type, patients with more severe variant face therapy-resistant recurrence. Therefore we have set out to develop new therapeutic approaches to the disease with a particular focus on aggressive subtypes. Using a high-throughput systems level approach we have identified a novel synergistic combination of approved drugs and compounds in clinical trials.
Our initial screen assessed the potency of a panel of clinically applicable drugs by proliferation assays versus a defined panel of isogenic cell lines that are representative of the different neuroblastoma variants. We identified potential drugs combinations by three-dimensional dose response matrices and adopted Bliss values as a quantitative measure of the synergy. The striking synergy was observed in SH-SY5Y cell line using combinations of EGFR/HER2 inhibitors with the apoptosis inducing agents. We were able to validate the observation using colony formation assay. In contrast to single drug treatment, the combination completely abolished the clonogenic growth of neuroblastoma cells, showing the most tangible evidence of the synergy.
In order to evaluate our results in more aggressive disease subtypes, we tested our combination in SH-SY5Y cell line with transiently overexpressed N-Myc and in N-Myc-amplified IMR5-75 cell line. Notably, even in this setting we could recapitulate our findings, suggesting that this combination of drugs is highly potent in the chemo-resistant tumor subtypes as well. The same effect was observed when we transiently overexpressed TrkA in SH-SY5Y, mimicking yet another neuroblastoma variant.
Pursuing the exact mechanism of the synergy, we have tested the combination in breast cancer cells. To our surprise, the synergistic effect was still present in HER2 negative cell line, but completely absent in the HER2 positive one. We also exchanged the dual EGFR/HER2 inhibitor drug with more potent EGFR inhibitors to conclude that a combination seems to be specific to a particular set of compounds and not necessarily to their main target spectra.
Our synergistic combination is highly potent in a large number of neuroblastoma conditions. Strong synergistic effect can be reached at doses much lower than required for the single drug treatment. Animal models that we are currently testing will enable quick translation of our data in clinics.
Citation Format: Branka Radic, Uwe Rix, Stefan Kubicek, Giulio Superti-Furga. Probing network fragilities in neuroblastoma by synergistic drug combinations. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5038. doi:10.1158/1538-7445.AM2013-5038
Abstract 5047: Impact of kidney progenitor cell differentiation status in Wilms tumorigenesis.
Authors: Huang Le , Mokkapati Sharada , Hu Qianghua , Huff Vicki 
Published: August 2014

Abstract
Wilms Tumor (WT) is a pediatric cancer of the kidney and one of the most common solid tumors of childhood. It is thought to arise from the undifferentiated renal mesenchyme, however, it is unknown which mesenchymal cell type can give rise to WT. The recent identification of different subsets of human WTs with defined gene expression signature, histology and clinical outcomes suggests that the cell differentiation status may be an important factor in the etiology of these subsets. Therefore, we hypothesize that WT can arise from fetal kidney cells at different differentiation stages and that different progenitor populations will result in different types of tumors in biology, pathology and molecular signature.
Our lab has generated the first genetic WT mouse model via somatic and mosaic ablation of Wilms Tumor 1 (Wt1), using a Wt1 conditional knockout allele with a ubiquitous tamoxifen-inducible CGH-Cre, and Igf2 biallelic expression. In this model, all types of embryonic kidney cells were randomly targeted. With this successful approach, we now have the ability to test the effect of introducing these alterations (Wt1 ablation in the context of Igf2 up-regulation or activation of β-Catenin) into kidney nephrogenic (Cited1-CreERT2) or stromagenic (Foxd1-CreERT2) progenitor cells. Very interestingly, when the mutations were introduced into the nephrogenic progenitors (Cited1-CreERT), WTs develop. These tumors express human WT markers and show a tubular histology with predominant epithelial cells, which histologically corresponds to the epithelial subset of human WTs. To further characterize the biology of these tumors, we will perform gene expression analysis and proteomic microarray analysis to identify aberrantly dysregulated signaling pathways.
This study will provide insight into the cellular etiology of WT which may help to identify new therapeutic approaches.
Citation Format: Le Huang, Sharada Mokkapati, Qianghua Hu, Vicki Huff. Impact of kidney progenitor cell differentiation status in Wilms tumorigenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5047. doi:10.1158/1538-7445.AM2013-5047
Abstract 5048: mTORC1/mTORC2 signaling in pediatric low grade glioma and pilocytic astrocytoma.
Authors: Shah Smit , Hutt Marianne , Karajannis Matthias A. , Raabe Eric , Eberhart Charles G. , Rodriguez Fausto J. 
Published: August 2014

Abstract
Pilocytic astrocytoma is the most frequent low grade glioma in children and young adults. Previous studies support a role for MAPK pathway signaling, and more recently AKT/mTOR, in its biology. mTOR operates as part of two different multiprotein signaling complexes, mTORC1 and mTORC2. In the current study we evaluated mTORC1/mTORC2 pathway activity in pediatric low grade astrocytoma. We used formalin-fixed paraffin embedded human pilocytic astrocytomas for immunohistochemical studies in tissue microarrays. Moderate (2+) to strong (3+) immunostaining was observed for pS6 in 66/114(58%), p4EBP1 in 35/116(30%), pElF4G in 66/113 (58%), and mTOR (total) in 52/114 (46%), supporting mTOR pathway activation in a subset of pediatric astrocytomas. Specifically, there was increased immunoreactivity in pilocytic astrocytomas of the optic nerve proper (pS6 39/54(72%), p4EBP1 22/54 (41%), 4IF4G 41/53 (77%), and mTOR 28/54 (52%)), a difference that was statistically significant for pS6, p4E-BP1 and pEIF4G (p&lt;0.05, Chi Square). Next, we studied total levels of Raptor (mTORC1 component) and Rictor (mTORC2 component). We observed moderate to strong Raptor reactivity in 81/142 (57%) and Rictor in 69/141(49%) pilocytic astrocytomas. By contrast, we observed increased Rictor immunostaining in 90/144 (63%) diffuse gliomas grade II-IV and Raptor in 28/147 (19%), a difference that was statistically significant between the two groups (p&lt;0.001, Chi Square). Next we studied in vitro the effect of mTORC1 blockade in pediatric low grade glioma cell lines Res 186 and Res 259 with a TORC1 inhibitor. Using the MTT assay, Res 186 cell growth was inhibited with 1nM and 10nM drug concentrations, compared with DMSO (p&lt;0.005, t-test), but the effect was less pronounced in Res 259. Additionally, pS6 levels were decreased by Western Blot in Res 186 cells, but not in Res 259, consistent with mTORC1 inhibition of Res 186 cells. The findings suggest that the mTOR pathway is active in a subset of pediatric low grade gliomas, that it varies by clinicopathologic subtype, and that it is primarily mediated by mTORC1 compared with other glioma subtypes. Furthermore, mTOR may represent a therapeutic target in pediatric low grade glioma that merits further investigation.
Citation Format: Smit Shah, Marianne Hutt, Matthias A. Karajannis, Eric Raabe, Charles G. Eberhart, Fausto J. Rodriguez. mTORC1/mTORC2 signaling in pediatric low grade glioma and pilocytic astrocytoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5048. doi:10.1158/1538-7445.AM2013-5048
Abstract 5052: Maximal SHH-driven medulloblastoma growth requires coordinate CXCR4 activation.
Authors: Ward Stacey , Sengupta Rajarshi , Rubin Josh 
Published: August 2014

Abstract
Medulloblastoma is the most common malignant brain tumor of childhood. Even with current intensive treatments there is still significant morbidity and mortality associated with this diagnosis. Recent hope for improved outcome derives from the stratification of medulloblastoma into four molecular subtypes and the promise that subtype-specific targeted therapy will be more efficacious and less toxic. However, even within specific subtypes there can be variable outcomes suggesting that further subclasification will be required. We have shown that CXCR4, a G-protein coupled receptor important for neuronal cell migration, is differentially expressed within the Sonic hedgehog (SHH) subtype of medulloblastoma (CXCR4hi and CXCR4lo) and that activation of CXCR4 was required for maximal medulloblastoma growth in vitro and in vivo. Here we investigate the molecular basis for the interaction between the SHH and CXCR4 pathways and the therapeutic potential of combined SHH and CXCR4 antagonism for the treatment of medulloblastoma.
Using primary cultures of SHH-driven medulloblastoma cells as well as their normal developmental counterpart, cerebellar granule precursor cells (GPCs), we found that SHH activation enhances CXCR4 surface localization and promotes prolonged CXCL12-induced GαI signaling. We hypothesized that this was due to SHH inhbition of CXCR4 desensitization and investigated the effects of SHH treatment on proteins involved in CXCR4 trafficking including: ferritin heavy chain, GRKs, arrestins and CXCR7. We found that while SHH had no effect on ferritin heavy chain expression, It did alter the abundance of a subset of GRKs, arrestins and CXCR7. In light of these data we developed a model for multi-tiered regulation of CXCR4 signaling by the SHH pathway that suggested combined SHH and CXCR4 antagonism would have a superior anti-tumor effect compared to SHH antagonism alone. We verified this by in vivo treatment of primary murine SHH-driven (SmoA1) medulloblastoma xenografts with the SHH and CXCR4 antagonists vismodegib and plexiflor. Together these data identify new targets and a new approach for the treatment of SHH-driven medulloblastoma.
Citation Format: Stacey Ward, Rajarshi Sengupta, Josh Rubin. Maximal SHH-driven medulloblastoma growth requires coordinate CXCR4 activation. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5052. doi:10.1158/1538-7445.AM2013-5052
Abstract 5072: Human tumor derived Oncoprint® platform predicts molecular mechanism of sensitivity and resistance to Fragmin in pancreatic cancer.
Authors: Sundaram Mallikarjun , Thiyagarajan Saravanan , Dhandapani Muthu , Brijwani Nilesh , Prasath Arun , Thayakumar Allen , Kamal Ameer , Radhakrishnan Padhma , Majumder Biswanath , Ulaganathan Baraneedharan , Majumder Pradip K. 
Published: August 2014

Abstract
One of the formidable challenges in cancer therapeutics is developing and validating a highly effective preclinical testing platform. However, existing in vitro and in vivo testing platforms show limited success. In this context, we have developed Oncoprint®, a novel clinically relevant preclinical platform demonstrated to have very high correlation to clinical outcome for chemotherapeutics as well as targeted drugs in multiple solid and hematological cancers (with overall sensitivity of 88% and specificity of 90% in more than 500 patients). Oncoprint® is a rapid reproducible ex-vivo tumor explant system, developed to mimic native tumor microenvironment. By including autologous paracrine growth factors, cancer specific customized matrix support, autologous immune environment along with other growth promoting conditions, significant improvements were observed in viability, proliferation of tumors including retention of tumor/stroma, cancer phenotypes, integrity at micro-architecture level and maintenance of functional signaling network. Using this platform we assessed the anti-tumor efficacy of Fragmin (a low molecular weight heparin-LMWH) alone as well as in combination with various Standard-Of-Care drugs (SOCs) and compared the outcome with efficacy derived from the use of SOCs alone in twenty patient derived pancreatic tumors. Clinical trial data indicates that Fragmin when administered in patients with advanced pancreatic cancer decreased levels of circulating-tissue factor antigen and attenuated induction of cellular invasion in their blood.
Oncoprint data indicates that Fragmin has potent anti-angiogenic activity as a single agent (in ∼ 77% tumor samples) and enhanced anti-proliferative and apoptotic effect in combination with SOC (Cisplatin and Gemcitabine) compared to SOC alone in ∼ 30% of these pancreatic tumors. . Our study has been powered to include 75-100 patient derived refractory pancreatic tumors for further evaluation. Detailed molecular profiling studies are underway to understand the mechanism of action of this drug to delineate the biology behind response in the responder sub-population.
Citation Format: Mallikarjun Sundaram, Saravanan Thiyagarajan, Muthu Dhandapani, Nilesh Brijwani, Arun Prasath, Allen Thayakumar, Ameer Kamal, Padhma Radhakrishnan, Biswanath Majumder, Baraneedharan Ulaganathan, Pradip K. Majumder. Human tumor derived Oncoprint® platform predicts molecular mechanism of sensitivity and resistance to Fragmin in pancreatic cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5072. doi:10.1158/1538-7445.AM2013-5072
Abstract 509: RNF115/BCA2 E3 ubiquitin ligase promotes breast cancer cell proliferation through targeting p21Waf1/Cip1 for ubiquitin-mediated degradation .
Authors: Wang Zehua , Seth Arun , Chen Ceshi 
Published: August 2014

Abstract
The E3 ubiquitin ligase Ring Finger Protein 115 (RNF115), also known as Breast Cancer Associated gene 2 (BCA2), has previously been reported to be overexpressed in estrogen receptor (ERα) positive breast tumors and to promote breast cell proliferation; however, the mechanism is unknown. In this study, we demonstrated that silencing of BCA2 by siRNA in two ERα-positive breast cancer cell lines MCF7 and T47D decreases cell proliferation and increases the protein levels of the cyclin-dependent kinases inhibitor p21Waf/Cip1. The protein stability of p21 was negatively regulated by BCA2. BCA2 directly interacts with p21 and promotes p21 ubiquitination and proteasomal degradation. Knockdown of p21 partially rescues the cell growth arrest induced by the BCA2 siRNA. These results suggest that BCA2 promotes ERα-positive breast cancer cell proliferation at least partially through down-regulating the expression of p21.
This study was supported by National Nature Science Foundation of China (81072162, 81120108019, and U1132605) .
Citation Format: Zehua Wang, Arun Seth, Ceshi Chen. RNF115/BCA2 E3 ubiquitin ligase promotes breast cancer cell proliferation through targeting p21Waf1/Cip1 for ubiquitin-mediated degradation . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 509. doi:10.1158/1538-7445.AM2013-509