bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract B47: Potent and selective CK2 kinase inhibitors with effects on Wnt pathway signaling in vivo
Authors: Dowling James E.
Published: May 2016

The serine/threonine protein kinase CK2, which exists as a constitutively active, hetero-tetrameric complex consisting of two catalytic (α or α') and two regulatory (β) subunits, has emerged as an attractive drug discovery target in oncology. Among its diverse functions, CK2 modulates cellular signaling pathways that are frequently activated in cancer, including PI3K/AKT, NFκB and Wnt. In order to explore the reported links between CK2 kinase activity and Wnt pathway signaling we sought to identify a potent, selective inhibitor of CK2 kinase with suitable physicochemical properties and pharmacokinetics for hypothesis testing in vivo. Starting from a pyrazolo[1,5-a]pyrimidine lead (1), we identified compound 2, a potent CK2 inhibitor with picomolar affinity (CK2a KD = 10 pM) that is highly selective against other kinase family enzymes and inhibits Wnt pathway signaling (Wnt luciferase reporter IC50 = 50 nM) in DLD-1 cells. Compound 2 has demonstrated good pharmacokinetics in preclinical species, depletes β-catenin in vivo and exhibits a high level of activity (TGI > 90%) as a monotherapy in HCT-116 xenografts at tolerated doses.

Citation Format: James E. Dowling. Potent and selective CK2 kinase inhibitors with effects on Wnt pathway signaling in vivo. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B47.
Abstract B62: AKT3 expression modulates chemosensitivity to aurora kinase inhibitors
Authors: Noguchi Kohji , Katayama Kazuhiro , Sugimoto Yoshikazu
Published: May 2016

The aurora kinases in human consist of three members, Aurora A, B and C (AURKA, B and C). They are involved in cell cycle progression, especially in mitosis, and aberrant expressions of them are reported in many cancer tissue types. Therefore, AURKs would serve as useful molecular targets for anti-cancer agents and many investigational drugs are currently under development. To understand pharmacological determinants affecting the chemosensitivity to aurora kinase inhibitors, we have established five resistant cell lines to an aurora kinase inhibitor VX 680 by treating human colon cancer HCT 116 cells in vitro with increasing concentrations of VX 680 (40∼200 nmol/L) over a period of 6 months. These VX 680-resistant clones showed aneuploidy and cross-resistance to other aurora kinase inhibitors AZD1152-HQPA and MLN8237. Regarding drug resistance-associated molecules, P-gp and BCRP overexpression were not common to the VX 680-resistant clones, despite the fact that overexpression of P-gp and BCRP conferred strong resistance to VX 680 and AZD1152-HQPA. Gene expression analysis by cDNA microarray indicated that Akt3 was up-regulated in the VX 680-resistant cells. Transient overexpression of myristylated-Akt3 in Hela cells repressed AZD1152-HQPA-induced cell death and polyploidy induction, and stable expression of myristylated-Akt3 in HCT 116 cells induced resistance to both VX 680 and AZD1152-HQPA. In addition, confocal microscopic study showed that endogenous AKT3 was detected during mitosis. These observations suggest that AKT3 activity can affect the mechanism for the chemosensitivity to aurora kinase inhibitors.

Citation Format: Kohji Noguchi, Kazuhiro Katayama, Yoshikazu Sugimoto. AKT3 expression modulates chemosensitivity to aurora kinase inhibitors. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B62.
Abstract B81: Analogues of the chromenone namoline as inhibitors of lysine specific demethylase 1 (LSD1)
Authors: Schulz-Fincke Johannes , Schmitt Martin L. , Carlino Luca , Haydn Tinka , Willmann Dominica , Metzger Eric , Fulda Simone , Schüle Roland , Sippl Wolfgang , Jung Manfred
Published: May 2016

Since it had been discovered in 2004, lysine-specific-demethylase 1 (LSD1) has been emphasized as a potential target for anticancer drugs. The physiological role of LSD1 is versatile which can be seen in its function in different LSD1-related protein complexes such as CoREST with the androgen receptor. Interacting with those various molecular domains, LSD1 leads to e.g. a regulation of gene expression and control of hematopoietic differentiation. So it is hardly surprising that several LSD1 inhibitors are already in clinical trials.

Namoline has been identified in collaboration with other groups using a bioinformatics approach based on active site similarity and a focused library screen. This hit impairs LSD1 activity in-vitro and in-vivo and is a promising starting compound for further investigations. Our latest developed heterogeneous assay-systems are resistant against auto-fluorescence and maybe will give us further insights into biophysiological interactions between inhibitors and the targeted enzyme. Based upon on this, we report structure-activity studies of namoline and its improved analogues which lead up to a 40-fold increased potency and retained selectivity over MAO-A and B. We show that namoline and its potent analogues have antiproliferative activity in Rhabdomyosarcoma cells with slightly improved efficacy for the new analogues.

Citation Format: Johannes Schulz-Fincke, Martin L. Schmitt, Luca Carlino, Tinka Haydn, Dominica Willmann, Eric Metzger, Simone Fulda, Roland Schüle, Wolfgang Sippl, Manfred Jung. Analogues of the chromenone namoline as inhibitors of lysine specific demethylase 1 (LSD1). [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B81.
Abstract C56: Platinum containing anti-cancer agents as targeted therapeutics
Authors: Bruno Peter M. , Park Ga Young , Murai Junko , Liu Yunpeng , Pritchard Justin , Pommier Yves , Lippard Stephen J. , Hemann Michael T.
Published: May 2016

Cisplatin and its analogs are one of the most widely used family of cancer chemotherapeutics. However, despite a diverse array of analogs having been synthesized over the past decades, the underlying assumption has been that they all work similarly by damaging DNA. Utilizing a unique multi-platform genetic approach we show that this is not the case, and that small modifications to the core structure of cisplatin can produce unexpected changes in mechanism of action. Specifically, we found oxaliplatin and a subset of mono-functional cisplatin analogs closely resembled transcription and translation inhibitors. This set of platinum-based agents do not rely on traditional cisplatin repair and tolerance pathways such as nucleotide excision repair, homologous recombination and inter-strand cross-link repair. Instead, we've demonstrated oxaliplatin treatment kills cells by eliciting a ribosome biogenesis stress response. Additionally, across a panel of human cell lines, we've shown that higher expression of ribosomal proteins correlates with resistance to these transcription/translation inhibitor-like platinum agents. From this analysis, and by analyzing and comparing human patient tumor expression data, we've concluded that oxaliplatin treatment is best applied in tumors that have developed a heightened dependence on translation. Thus, while commonly regarded as “blunt weapons”, our current arsenal of genotoxic anti-cancer agents utilizes surprisingly diverse mechanisms that suggest new paradigms for their application in patients.

Citation Format: Peter M. Bruno, Ga Young Park, Junko Murai, Yunpeng Liu, Justin Pritchard, Yves Pommier, Stephen J. Lippard, Michael T. Hemann. Platinum containing anti-cancer agents as targeted therapeutics. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C56.
Abstract C57: Discovery and development of replication protein A (RPA)-DNA interaction inhibitors for cancer chemotherapy
Authors: Gavande Navnath , VanderVere-Carozza Pamela S. , Mishra Akaash , Turchi John J.
Published: May 2016

Platinum (Pt)-based chemotherapeutics exert their efficacy via the formation of DNA adducts which interfere with DNA replication, transcription and cell division and ultimately induce cell death. DNA repair of Pt-DNA adducts via nucleotide excision repair (NER) or homologous recombination repair (HRR) can substantially reduce the effectiveness of the Pt therapy, which is a major contributor for cellular resistance. Inhibition of these repair pathways, therefore, holds the potential to sensitize cancer cells to Pt-treatment and increase the clinical efficacy. Replication protein A (RPA) is a single-stranded DNA binding protein that plays a crucial role in the NER and HRR pathways apart from its role in replication and DNA damage checkpoint activation. We have pursued the development of small molecule inhibitors of the RPA-DNA interaction as a mechanism to target RPA activity and increase the efficacy of Pt-based cancer chemotherapy. We have developed an inhibitor, TDRL-551, that targets the central oligonucleotide/oligosaccharide binding folds in DNA binding domains A and B (DBD-A/B) of the 70 kDa RPA subunit. This lead compound shows synergy with cisplatin in tissue culture models of epithelial ovarian cancer (EOC) and in vivo efficacy, as a single agent as well as in a combination with platinum, in a lung cancer xenograft model. We have expanded our synthetic scheme and defined structure-activity relationships (SAR) towards optimization of TRDL-551 as an anticancer therapeutic for the treatment of lung and ovarian cancer.

Supported by NIH grants R01 CA180710 and R41CA162648 to JJT.

Citation Format: Navnath Gavande, Pamela S. VanderVere-Carozza, Akaash Mishra, John J. Turchi. Discovery and development of replication protein A (RPA)-DNA interaction inhibitors for cancer chemotherapy. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C57.
Abstract C77: Oncogenic drivers reactivate kinase-inhibited focal adhesion kinase (FAK) through phosphorylation of effector residues
Authors: Figel Sheila , Lenzo Felicia , Marlowe Timothy , Cance William
Published: May 2016

Introduction: Focal Adhesion Kinase (FAK) is a critical signaling molecule showing elevated expression in nearly all tumor types. Phosphorylation of key tyrosine residues within FAK underlies its dual roles as both a kinase and a molecular scaffold that integrates signals from major oncogenes. Though FAK has emerged as a major drug target, inhibitors developed to date singularly target its kinase activity, leaving the scaffolding of oncogenic drivers intact. Our studies demonstrate that cells treated with FAK kinase inhibitors PF-573228, PF-562271, and defactinib retain phosphorylation of several key tyrosine residues downstream of oncogenic receptor tyrosine kinases (RTKs).

Methods: We examined the phosphorylation status of key FAK scaffolding sites Y861 and Y925 in RTK expressing normal and cancer cells treated with FAK kinase inhibitors PF-573228, PF-562271, and defactinib. As Src kinase is known to directly phosphorylate Y861 and Y925, we also tested phosphorylation of these sites by RTKs in Src/Yes/Fyn (SYF) MEFs, which lack the major Src family kinases.

Results: In cancer cells treated with FAK kinase inhibitors, multiple RTKs (HER2/3, PDGFR, and EGFR) activated FAK through the phosphorylation of effector tyrosines. Activation of HER2/3 in MDA-MB-453 breast cancer cells, PDGFR in U-87 glioblastoma cells, and EGFR in A549 lung cancer cells all stimulated Y861/Y925 phosphorylation in the presence of each of the three FAK kinase inhibitors. Moreover, Y861/Y925 phosphorylation occurred downstream of PDGFR and EGFR in Src-null SYF MEFs, demonstrating that RTK FAK targeting does not require Src. Finally, in vitro studies demonstrated that RTKs can directly phosphorylate these sites on FAK.

Conclusion: We have identified a novel mechanism through which FAK retains signaling activity in the presence of kinase inhibitors. Continued FAK signaling in tumor cells which overexpress HER2, EGFR or PDGFR may therefore be a mode of clinical resistance to FAK kinase inhibitors.

Citation Format: Sheila Figel, Felicia Lenzo, Timothy Marlowe, William Cance. Oncogenic drivers reactivate kinase-inhibited focal adhesion kinase (FAK) through phosphorylation of effector residues. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C77.
Abstract C92: HCI-2577 inhibits LSD1 and modulates histone marks in Ewing's sarcoma models
Authors: Bearss Jared J. , Neiss Adrianne , Liu Xiao-Hui , Vankayalapati Hariprasad , Sharma Sunil
Published: May 2016

Lysine-specific demethylase 1 (LSD1/AOF2/KDM1A) is a flavin-dependent histone demethylase that catalyzes the posttranslational oxidative demethylation of mono- and dimethylated lysines on histones. Methylation of lysine residues on histones can signal transcriptional activation or repression depending on the specific residue involved. H3K4me2 is a transcription-activating mark, and demethylation of this mark by LSD1 prevents expression of tumor suppressor genes important in human cancer. Whereas, H3K9 methylation is a repressive mark and LSD1 activity has been shown to upregulate tumor promoting pathways. This makes LSD1 emerge as an important target for the development of novel antitumor inhibitors. The compound HCI-2577 was identified as a potent reversible inhibitor of LSD1 enzymatic activity, with an IC50 of 7nM. In a diverse cell screen panel for cellular viability, Ewing's sarcoma was identified as being sensitive to HCI-2577. Here we show that HCI-2577 is efficacious in in vivo models of Ewing's sarcoma as a single agent with a favorable drug profile. In conclusion, HCI-2577 is a novel LSD-1 inhibitor with therapeutic potential in Ewing's sarcoma demonstrating promising activity in biochemical, cell-based and in vivo assays.

Citation Format: Jared J. Bearss, Adrianne Neiss, Xiao-Hui Liu, Hariprasad Vankayalapati, Sunil Sharma. HCI-2577 inhibits LSD1 and modulates histone marks in Ewing's sarcoma models. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr C92.
Abstract PR11: Phase 1 study of a novel PARP1/2 selective inhibitor, BGB-290
Authors: Lickliter Jason , Gan Hui , Meniawy Tarek , Yang Jason , Wang Lai , Luo Lusong , Millward Michael
Published: May 2016

This abstract has been withheld from publication due to its inclusion in the AACR-NCI-EORTC Molecular Targets Conference 2015 Official Press Program. It will be posted online at the time of its presentation in a press conference or in a session.

Citation Format: Jason Lickliter, Hui Gan, Tarek Meniawy, Jason Yang, Lai Wang, Lusong Luo, Michael Millward. Phase 1 study of a novel PARP1/2 selective inhibitor, BGB-290. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr PR11.
Abstract PR12: Discovery and preclinical evaluation of cEt-modified KRAS antisense oligonucleotide inhibitors
Authors: Revenko Alexey S. , Ross Sarah J. , Hanson Lyndsey L. , Ellston Rebecca , May Chris , Pandey Sanjay K. , Buckett Linda K. , Klein Stephanie K. , Revill Mitchell , Hudson Kevin , Monia Brett P. , Blakey David C. , Lyne Paul , MacLeod Allan R.
Published: May 2016

KRAS is one of the most frequently mutated genes in cancer and its activation is thought to underlie the pathogenesis of up to 30% of all human tumors. However, to date KRAS has proven difficult to target with traditional pharmacologic approaches. Antisense technology is particularly attractive for such difficult drug targets as antisense oligonucleotide (ASO) inhibitors can be designed based on a targets RNA sequence alone.

cEt ASOs have been recently described and demonstrated to have significantly increased potency over previous generation ASO chemistries. Moreover, STAT3Rx/AZD9150, a cEt modified ASO targeting STAT3 mRNA was recently shown to produce robust STAT3 depletion in a broad range of xenograft models (AACR 2013) and importantly has also demonstrated promising single-agent antitumor activity in patients with advanced treatment-refractory cancers in phase I studies (ASCO 2013, EORTC 2014).

Here, we describe the preclinical evaluation of potent and selective cEt ASOs targeted to human or mouse KRAS mRNA. A human-specific KRAS cEt ASO which potently and selectively down-regulated KRAS demonstrated anti-proliferative effects and the expected down-stream pathway inhibition in a panel of KRAS mutant NSCLC, CRC and PDAC cells. The KRAS ASO was differentiated from MAPK pathway inhibitors selectively inhibiting the proliferation of KRAS mutant not KRAS wild type cells and not causing feedback reactivation of the MAPK or PI3K pathways. Systemic delivery of the KRAS ASO to mice bearing KRAS mutant NSCLC or CRC xenografts resulted in significant inhibition of KRAS tumour expression and antitumor activity. Importantly, the KRAS ASO also showed significant target knockdown and antitumor effects in KRAS mutant NSCLC patient-derived xenografts (PDX).

Finally, potent and selective murine-specific KRAS ASO produced robust target knockdown in a broad set of tissues without detectable tolerability signals associated with ASO-mediated systemic KRAS inhibition.

Taken together these data suggest that KRAS ASOs are an attractive therapeutic approach to target KRAS for the treatment of human cancers.

Citation Format: Alexey S. Revenko, Sarah J. Ross, Lyndsey L. Hanson, Rebecca Ellston, Chris May, Sanjay K. Pandey, Linda K. Buckett, Stephanie K. Klein, Mitchell Revill, Kevin Hudson, Brett P. Monia, David C. Blakey, Paul Lyne, Allan R. MacLeod. Discovery and preclinical evaluation of cEt-modified KRAS antisense oligonucleotide inhibitors. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr PR12.
Abstract A08: IGF1R as a key target in high risk, metastatic medulloblastoma
Authors: Svalina Matthew N. , Kikuchi Ken , Abraham Jinu , Lal Sangeet , Davare Monika A. , Peckham Jennifer L. , Cho Yoon-Jae , Jackson Melanie , Guillaume Daniel J. , Selden Nathan R. , Bigner Darell D. , Nazemi Kellie J. , Green Sarah C. , Corless Christopher L. , Gultekin Sakir , Rubin Brian P. , Woltjer Randall , Keller Charles
Published: May 2016

The risk or presence of metastasis in childhood medulloblastoma represents a substantial cause of morbidity and mortality. Relatively little has been known about the molecular mechanisms of medulloblastoma dissemination throughout the cerebrospinal axis. To determine potential interventions that address both metastasis and tumor growth, we examined the expression of cytokines and growth factors in the CSF of metastatic medulloblastoma patients that were also present in the conditioned media of metastatic, MYC amplified medulloblastoma cell lines and/or cell culture models of the leptomeninges. The presence of IGF1, the IGF-sequestering protein Igfbp3, which can be cleaved by metal metalloproteases (MMP) and the serine protease tPA, and the presence of corresponding protease modulators TIMP1 and SerpinE1/PAI-1, led us to explore the bioactivity of IGF1 in medulloblastoma. IGF1 led not only to receptor phosphorylation but also increased migration and increased relative cell growth. A tumor cell viability screen of 60 clinically-related compounds prioritized IGF1R inhibitors. Our findings support a model whereby medulloblastoma tumor cells actively migrate, rather than arrive passively, to the leptomeningeal cell surface and provide a rationale for exploring IGF1R as a target for therapeutics in future clinical trials.

Citation Format: Matthew N. Svalina, Ken Kikuchi, Jinu Abraham, Sangeet Lal, Monika A. Davare, Jennifer L. Peckham, Yoon-Jae Cho, Melanie Jackson, Daniel J. Guillaume, Nathan R. Selden, Darell D. Bigner, Kellie J. Nazemi, Sarah C. Green, Christopher L. Corless, Sakir Gultekin, Brian P. Rubin, Randall Woltjer, Charles Keller. IGF1R as a key target in high risk, metastatic medulloblastoma. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr A08.
Abstract A15: A human mini brain model of pediatric GBM
Authors: Ismail Amin
Published: May 2016

Glioblastoma (GBM) is the most devastating brain cancer with dismal prognosis both in adults and children and accounts for 16% of primary brain tumors. Despite aggressive therapeutic approaches, the majority of patients die within one year after diagnosis. Giving the limitation of current GBM mouse models, which do not reflect the biological properties of human tumors, in particular, tumor heterogeneity and pathogenesis, there is a growing need for new models. Current in vitro 3D models involve the use of hydrogel scaffolds and cell lines, which do not represent a viable developmental context where the tumor mass interacts with and invades the surrounding brain tissues. Starting with pluripotent human embryonic stem cells we reproduced a 3D tissue structure (so-called cerebral organoid) representing a developing human brain in vitro. We engineered these mini-brains to express oncogenic hits responsible for the derivation of tumors in pediatric GBM patients. Pediatric GBM is driven by a combination of epigenetic and genetic hits including the expression of a mutant histone H3 variant H3F3A (mutated at K27M or G34R) or a gain of function mutant isocitrate dehydrogenase IDH1R132H in combination with the loss of the histone remodeling factor ATRX and/or p53 tumor suppressor. We used a combination of these oncogenic hits to create a model of tumor engineering representing the first 3D human tissue model of GBM. This model combines the accurate multi-lineage differentiation and physiology of human brain with the easiness of manipulation of in vitro systems.

H&E staining of the modified organoids shows remarkable dysplasia reminiscent of human primary glioma. Different genetic hits result in different type of dysplasia with IDH1R132H showing distinct morphology, suggestive of a broad range of applicability to model oncogenic-dependence in pediatric GBM.

Cerebral organoids may also be used as a model to study tumor invasion starting with glioma stem-like cells (GSCs, which are believed to be the tumor-initiating cells in GBM). Indeed 923 GSCs (which are not invasive in mice brain) quickly and spontaneously (within few days) invade a co-cultured cerebral organoid.

This study is the first to engineer a human CNS tumor in vitro. The model carries a tremendous potential to uncover the pathogenesis and initiation of brain cancer in a pediatric setting.

Note: This abstract was not presented at the conference.

Citation Format: Amin Ismail. A human mini brain model of pediatric GBM. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr A15.
Abstract A23: Bone marrow derived myeloid cells orchestrate resistance to antiangiogenic therapy in novel chimeric mouse model of glioblastoma
Authors: Achyut B.R , Shankar Adarsh , Iskander Asm , Ara Roxan , Angara Kartik , Knight Robert , Scicli Alfonso , Arbab Ali
Published: May 2016

Glioblastoma (GBM) is considered as hypervascular form of brain tumors. Anti-angiogenic therapies (AAT) were used as an adjuvant against VEGF-VEGFR pathway to normalize blood vessels. Surprisingly, AAT resulted into marked hypoxia and recruited bone marrow derived cells (BMDCs) to the tumor microenvironment (TME). Nonavailability of in vivo model limits investigation of BMDCs in AAT resistance. We established a novel chimeric mouse model using as low as 5x106 BM cells from GFP+ transgenic mice, administered through i.v route in athymic nude mice following whole body irradiation, which resulted in >70% engraftment within 14 days. We exploited chimeric mouse model to develop orthotopic U251 tumor and tested receptor tyrosine kinase inhibitors and CXCR4 antagonist against GBM. Increased infiltration of GFP+ BMDCs acquiring suppressive myeloid and endothelial phenotypes in TME, and increased tumor growth were observed following treatments. Inhibition of CSFR1+ myeloid cells using GW2580 reduced tumor growth by decreasing myeloid and angiogenic cells in TME. This was followed by decreased inflammatory, proangiogenic and immune suppressive factors compared to vehicle and other treated groups. In conclusion, we developed preclinical chimeric model of GBM and role of tumor infiltrated BMDCs were investigated in context of resistance of AATs by utilizing state of art multispectral optical and MR imaging. Study suggests that inhibiting immune suppressive myeloid cells could provide a better therapeutic benefit in GBM.

Citation Format: B.R Achyut, Adarsh Shankar, Asm Iskander, Roxan Ara, Kartik Angara, Robert Knight, Alfonso Scicli, Ali Arbab. Bone marrow derived myeloid cells orchestrate resistance to antiangiogenic therapy in novel chimeric mouse model of glioblastoma. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr A23.
Abstract A34: Id-1 mediates glioma stem cell chemoresistance to temozolomide
Authors: Celebre Angela , Wu Megan YiJun , Remke Marc , Taylor Michael , Karamchandani Jason , Das Sunit
Published: May 2016

Introduction: Id-1 (inhibitor of differentiation and DNA binding) is a transcriptional regulator involved in stem cell maintenance. It has previously been shown to regulate self-renewal and confer chemoresistance in colon cancer stem cells. Id-1 has not been studied within the context of glioblastoma (GBM). We hypothesized that Id-1 mediates glioma stem cell (GSC) survival in response to chemotherapy and subsequently promotes tumour recurrence.

Methods: To study the role of Id-1 in response to chemotherapy in vitro, three GSC lines were treated with the chemotherapy agent, temozolomide (TMZ), for seven days. Immunoblot and comparative QT-PCR were used to measure Id-1 protein and mRNA expression post-TMZ, respectively. To evaluate Id-1 expression in patient samples, we constructed a tissue microarray (TMA), which included 77 tissue specimens from patients diagnosed with GBM. Detailed clinical information was available for all of the selected samples, including survival times, treatment regimens, and primary versus recurrent tumor status. Immunohistochemistry was performed on the TMA and Id-1 protein expression was subsequently quantified using Panoramic Image Analysis Software Platform. Id-1 expression was correlated to survival outcome, along with other clinically relevant variables. We also employed a bioinformatics approach, exploring survival data from The Cancer Genome Atlas (TCGA) database that were based on Id-1 expression for patients diagnosed with GBM.

Results: Id-1 expression in GSCs strongly increased in response to increasing doses of TMZ in vitro (0 uM, 25 uM, 100 uM). In patient tumor samples (n=77), Id-1 expression did not correlate with survival. However, among the recurrent patients who received chemotherapy after primary tumor resection (n=6), patients with increased Id-1 expression post-chemotherapy had a shorter latency to recurrence compared to patients with decreased Id-1 expression post-chemotherapy. Finally, the TCGA data corroborated our TMA patient data, finding comparable overall survival trends between patients with high versus low Id-1 expression.

Conclusion: These findings demonstrate that Id-1 levels increase in response to chemotherapy, suggesting its potential role in chemoresistance. Since resistance to chemotherapeutic drugs is one of the major reasons for treatment failure in glioblastoma, Id-1 inactivation may serve as a novel strategy for enhancing therapy and improving outcomes in patients with the disease.

Citation Format: Angela Celebre, Megan YiJun Wu, Marc Remke, Michael Taylor, Jason Karamchandani, Sunit Das. Id-1 mediates glioma stem cell chemoresistance to temozolomide. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr A34.
Abstract A40: CD74: a potential mediator of resistance in the treatment of Glioblastoma
Authors: Magorrian Sinead , Coulter Jonathan , Flannery Tom , Scott Christopher , Burden Roberta
Published: May 2016

CD74 is a rapidly internalised transmembrane protein, highly expressed in a number of cancers and is associated with increased proliferation and invasion of tumourigenic cells. CD74 is an attractive biomarker to monitor tumour progression and predict overall survival as expression levels have shown to be increased on the cell surface. Recent studies have suggested CD74 plays a potential role in tumour cell response to treatment, showing direct correlation between expression and response. The overall survival of patients with glioblastoma is poor, as treatment options are limited and not well defined. The standard options for the majority of patients is a combination of surgical resection, radiation and chemotherapy. The aim of this study is to investigate the association between CD74 expression and response to radiation and chemotherapy. A panel of glioblastoma cells lines were analysed by RT-PCR and western blotting to examine CD74 expression. Results indicated LN229 and U87MG cells expressed CD74 and using two independent shRNA constructs, CD74 expression was successfully knocked-down in both these lines to enable further study. Interrogation of these CD74-depleted lines indicated a significant reduction in proliferation and migration compared to a non-targeting control. When exposed to increasing doses of radiation the survival fraction of CD74 deficient cells was greater than that of the non-targeting control, suggesting an association between CD74 expression and sensitivity to radiation therapy in glioblastoma cell lines. However, when cells were exposed to increasing doses of Temozolomide there was a decrease in survival fraction of CD74-depleted cells compared to non-targeting controls, which showed no response to treatment. This study aims to further investigate the mechanism by which these change in sensitivity to treatment are mediated and determine if CD74 could not only be used as a marker for tumour progression, but to determine the most appropriate treatment option for patients.

Citation Format: Sinead Magorrian, Jonathan Coulter, Tom Flannery, Christopher Scott, Roberta Burden. CD74: a potential mediator of resistance in the treatment of Glioblastoma. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr A40.
Abstract B30: MicoRNA mediated regulation of antiangiogenic resistance in glioblastoma
Authors: Jain Meenu , Achyut Bhagelu , Shankar Adarsh , Angara Kartik , Iskander Asm , Arbab Ali S.
Published: May 2016

Anti-angiogeneic therapies are being used in glioma due to high expression of vascular and angiogenic growth factors but without improved survival and tumor recur. Our study used vatalanib (PTK) in U251 tumor cells which secretes proangiogenic and proinvasive proteins. We found 7 proteins (MMP-2, MMP-9, SDF-1α, Tie-2, MCP-1, IL-8, VE Cadherin, and VEGFA) which were altered greater than 20 fold in both U251 complete medium and lysate. We hypothesized that miRNA regulation may be involved in overexpression of these secreted factors that might be responsible for antiangiogenic resistance in glioma. We performed miRNA profiling (Affymetrix miRNA v3 platform) in U251 glioma cell line treated with or without PTK drug under hypoxia and normoxia conditions. Fold changes were estimated using normoxia group as control against normoxia+PTK, hypoxia, hypoxia+PTK, and changes greater than 5 fold were considered for further analysis to investigate potential targets. We found miR-15a and miR-21 were > 7-fold upregulated in group with hypoxia+PTK treatment. Targetscan analysis showed mir-15a may target TNFAIP3, VEGFA and mir21 can target MMP-2, which were altered in U251 cell lysate. Our present study identified novel microRNAs and gene targets which may lead to antiangiogenic resistance in glioma and provide a basis for future clinical trials. In future, functional assays will confirm the role of candidate miRNAs in tumor vasculature development following antiangiogenic drug treatment.

Citation Format: Meenu Jain, Bhagelu Achyut, Adarsh Shankar, Kartik Angara, Asm Iskander, Ali S. Arbab. MicoRNA mediated regulation of antiangiogenic resistance in glioblastoma. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr B30.
Abstract B34: PDGFR-ID4-Notch axis is a common signaling pathway activated in glioma stem cells and endothelial cells
Authors: Jeon Hye-Min , Kim Hyunggee
Published: May 2016

Glioma stem cells (GSCs), which reside within the perivascular niche (PVN) to maintain self-renewal capacity, are responsible for glioblastoma initiation, progression, and recurrence. However, the molecular mechanisms controlling GSCs and endothelial cells in the PVN are poorly understood. Here, we report that PDGF-driven activation of nitric oxide (NO) synthase increases NO-dependent ID4 expression, which promotes Jagged-Notch activity through miR-129 suppression in GSCs and endothelial cells. ID4 also increases PDGF-PDGFR signaling in a direct or miR-129-dependent manner, which drives the PDGFR-NO-ID4 signaling in GSCs and endothelial cells. This signaling circuit promotes tumor progression along with increased GSC self-renewal and growth of tumor vasculature in the PVN, which is dramatically suppressed by Notch inhibitor. ID4 levels correlate positively with NOS2, Hes1, and Hey1 and negatively with miR-129 in primary GSCs. Thus, targeting the PDGFR-NO-ID4 signaling circuit and Notch activity in the PVN might serve as an efficacious therapeutic modality for glioblastoma.

Citation Format: Hye-Min Jeon, Hyunggee Kim. PDGFR-ID4-Notch axis is a common signaling pathway activated in glioma stem cells and endothelial cells. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr B34.
Abstract B37: Tumor heterogeneity contributes to anti-EGFR therapy resistance in glioblastoma
Authors: Zanca Ciro , Cavenee Webster , Furnari Frank
Published: May 2016

Introduction: Glioblastoma is the most aggressive tumor type affecting the adult brain, with an overall patient survival from the time of diagnosis of about 15 months. Tumor promoting proteins such as EGFR (Epidermal Growth Factor Receptor) and its mutant form, EGFRvIII, are amplified in a subgroup of patients and have attracted attention as potential therapeutic targets. Unfortunately, kinase inhibition of EGFR or EGFRvIII has been proven to be ineffective due to resistance mechanisms that prevent the onset of cell death. Here we hypothesize that the presence of cytokines in the tumor microenvironment, in addition to their previously shown promotion of glioblastoma growth, also promote resistance to EGFR-directed therapies. To address this, we investigated core pathways known to protect cancer cells from induced cell death and tested novel treatment strategies of EGFR blockade in combination with inhibitors of cytokine-induced signaling effectors, activated by inter-clonal communication between heterogeneous tumor cell populations expressing EGFRvIII and EGFR.

Experimental procedures: For these studies we used human and mouse glioma cell lines engineered to express wild type (wt) EGFR, EGFRvIII, or an analog-sensitive (as)-allele of EGFRvIII, as well as primary human glioma neurospheres expressing amplified EGFRvIII. Expression of cell death-related molecules was determined by RT-qPCR to identify potential survival factors regulated by conditioned medium (CM) produced from EGFRvIII-expressing glioma cells. Findings were validated in vivo by orthotopic engraftment of heterogeneous tumors and measurement of tumor burden by fluorescence molecular tomography technology during single and combined drug therapy regimens.

Results and discussion: Previous results demonstrated that CM from EGFRvIII-expressing glioma cells enhances in vitro and in vivo growth of wtEGFR cells through an EGFRvIII-prompted IL-6/LIF paracrine mechanism. Here, our data indicate that EGFRvIII-CM additionally promotes resistance to EGFR inhibition in cells and tumors expressing wtEGFR. We show that IL-6/gp130-mediated signaling specifically promotes this resistance through mTORC2/NF-κB upregulation of the anti-apoptotic protein, Survivin (BIRC5). Blocking Survivin expression or pharmacologically inhibiting mTORC2 restores sensitivity to EGFR inhibitors.

Conclusion: The mTORC2/NF-κB/Survivin axis promotes resistance to EGFR inhibitors in glioblastoma and nominates targeting this pathway as a means to enhance efficacy of EGFR blockade.

Citation Format: Ciro Zanca, Webster Cavenee, Frank Furnari. Tumor heterogeneity contributes to anti-EGFR therapy resistance in glioblastoma. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr B37.
Abstract IA11: Targeting enhancers in CNS tumors
Authors: Bradner James
Published: May 2016

Master regulatory transcription factors instruct cell specification and dynamically modulate cell state via interactions with cis-regulatory elements, or enhancers, that together coordinate transcriptional programs. With an interest in understanding chromatin-dependent signal transduction to RNA polymerase in developmental and disease biology, we have undertaken to discover and optimize small molecule modulators of chromatin regulatory factors that function at enhancers. This research has produced informative chemical probes, with which we have validated hypotheses regarding BRD4 in chromatin-dependent signal transduction from MYC to promote cell growth, and the influence of EZH2 on silencing developmental programs. The mechanistic study of protoypical inhibitors of BRD4 and EZH2 led to the development of genome-wide measurements of drug localization, leading to insights into how small molecules modulate chromatin structure and function as well as fundamental insights into the organization of the regulatory landscape of the human genome. Here, mechanistic insights into the role of enhancers and enhancer factors in CNS tumors will be discussed, as well as translational opportunities for the development of epigenome-directed drugs in adult and pediatric tumors.

Citation Format: James Bradner. Targeting enhancers in CNS tumors. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr IA11.
Abstract IA22: Developing improved diffuse intrinsic pontine glioma mouse models
Authors: Becher Oren Josh
Published: May 2016

Recent genomic studies have identified novel drivers in DIPG pathogenesis. These include gain of function histone mutations (K27M in H3.3 or H3.1) found in 80% of DIPGs as well as activating mutations in Activin A Receptor, Type I (ACVR1) found in 25% of DIPGs. These studies also provide support for the existence of subtypes of DIPG with H3.3K27M mutations co-occurring with PDGFRA amplifications with an older age at presentation and H3.1K27M mutations co-occurring with ACVR1 mutations with a younger age at presentation. My laboratory has been using the RCAS/tv-a system to develop genetic mouse models for these DIPG subtypes that recapitulate the genetic alterations of the human disease. Our results thus far suggest that H3.3K27M is not sufficient to drive brainstem gliomagenesis on its own or with p53 loss in the early postnatal period but cooperates with platelet-derived growth factor-B (PDGF-B) in brainstem gliomagenesis. Similarly, mutant ACVR1 (R206H or G328V) cooperates with H3.1K27M and p53 loss to induce glioma-like lesions in mice. By contrast to the PDGF-B; H3.3K27M lesions that express Olig2, the mutant ACVR1; H3.1K27M; p53 deficient lesions are Olig2 negative but express CD44 and nestin. To examine whether the cell-of-origin will influence DIPG tumor incidence or latency, we induced murine DIPGs with PDGF-B, H3.3K27M, and p53 loss in three cell populations that express the following markers in the postnatal mouse brainstem: nestin, pax3 and Olig2. We will highlight the differential expression of these markers in the postnatal brainstem and resulting differences in tumorigenesis between these murine DIPGs induced in these three putative cells-of-origin. Lastly we will demonstrate the use of these models as preclinical tools.

Citation Format: Oren Josh Becher. Developing improved diffuse intrinsic pontine glioma mouse models. [abstract]. In: Proceedings of the AACR Special Conference: Advances in Brain Cancer Research; May 27-30, 2015; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2015;75(23 Suppl):Abstract nr IA22.
Abstract A18: Mismatch repair proteins recruit DNA methyltransferase 1 to sites of oxidative DNA damage
Authors: Ding Ning , Bonham Emily M. , Hannon Brooke E. , Baylin Stephen B. , O'Hagan Heather M.
Published: May 2016

At sites of chronic inflammation, epithelial cells are exposed to high levels of reactive oxygen species and undergo cancer-associated DNA methylation changes, suggesting that inflammation may initiate epigenetic alterations. Previously, we demonstrated that oxidative damage causes epigenetic silencing proteins to become part of a large complex that is localized to GC-rich regions of the genome, including promoter CpG islands that are epigenetically silenced in cancer. However, whether these proteins were recruited directly to damaged DNA or during the DNA repair process was unknown. Here we demonstrate that the mismatch repair protein heterodimer MSH2-MSH6 participates in the oxidative damage-induced recruitment of DNA methyltransferase 1 (DNMT1) to chromatin. Hydrogen peroxide treatment induces the interaction of MSH2-MSH6 with DNMT1, suggesting that the recruitment is through a protein−protein interaction. Importantly, the reduction in transcription for genes with CpG island-containing promoters caused by oxidative damage is abrogated by knockdown of MSH6 and/or DNMT1. Our findings provide evidence that the role of DNMT1 at sites of oxidative damage is to reduce transcription, potentially preventing transcription from interfering with the repair process. This study uniquely brings together several factors that are known to contribute to colon cancer, namely inflammation, mismatch repair proteins, and epigenetic changes.

Citation Format: Ning Ding, Emily M. Bonham, Brooke E. Hannon, Stephen B. Baylin, Heather M. O'Hagan. Mismatch repair proteins recruit DNA methyltransferase 1 to sites of oxidative DNA damage. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Sep 24-27, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2016;76(2 Suppl):Abstract nr A18.
Abstract A19: A novel MECP2 acetylation site regulates binding with ATRX and HDAC1
Authors: Pandey Somnath , Simmons Glenn E. , Malyarchuk Svitlana , Calhoun Tara N. , Pruitt Kevin
Published: May 2016

Tumorigenesis stems from errors incorporated in the genetic code and impaired epigenetic mechanisms involved in tumor suppression. Mutation in methyl-CpG-binding protein 2 (MeCP2) is known to cause a neurological disorder, rett syndrome (RTT), however its role in tumorigenesis remains poorly understood. We wanted to characterize how novel post-translational modifications might contribute to its function. MeCP2 regulates gene expression by recruiting co-repressors and histone deacetylases (such as HDAC1) to methylated gene promoters. MeCP2 modulates heterochromatin association by interacting with heterochromatin protein 1 (HP1). It was shown that MeCP2 interacts with and recruits ATRX, a SWI2/SNF2 DNA helicase/ATPase, to regulate gene expression at a subset of imprinted domains. A recent study showed that overexpression of Sirtuin1 (SIRT1) deacetylase leads to reduced levels of acetylation of ectopically expressed MeCP2. Using mass spectrometry, we report that upon pharmacological inhibition of SIRT1 in colon and breast cancer cell lines, endogenous MeCP2 is acetylated at key sites known to be critical for binding to DNA and transcriptional regulators. We mapped several novel acetylated sites and then created an acetylation mimetic mutation in MeCP2 (K171Q) and found that this mutant shows decreased binding to HDAC1 and ATRX in RKO cells. Similar results were obtained when SIRT1 was pharmacologically inhibited. Herein we show that conditions that induce MeCP2 acetylation in RKO cells do not alter its promoter occupancy at a subset of target genes analyzed but do cause a decreased binding to co-repressors such as HDAC1 and ATRX and also alters ATRX binding at a specific gene promoter. We also demonstrate that RKO cells over-expressing our acetylation mimetic mutant show reduced proliferation as compared to those over-expressing MeCP2-wild type (WT).

Citation Format: Somnath Pandey, Glenn E. Simmons Jr., Svitlana Malyarchuk, Tara N. Calhoun, Kevin Pruitt. A novel MECP2 acetylation site regulates binding with ATRX and HDAC1. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Sep 24-27, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2016;76(2 Suppl):Abstract nr A19.