bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract SY35-01: Unexpected results of prolonged EZH2 inhibition in an in vivo model for glioblastoma
Authors: Lohuizen Maarten van
Published: May 2015

Repressive Polycomb-group (Pc-G) protein complexes and the counteracting Trithorax-group (Trx-G) of nucleosome remodeling factors are involved in the dynamic maintenance of proper gene expression patterns during development, acting at the level of chromatin structure. As such, they are important controllers of cell fate and differentiation. When deregulated, these master switches of gene expression are strongly implicated in formation of a diverse set of cancers. Examples are the Pc-G gene Bmi1 and Ezh2 which are overexpressed in many cancers including glioblastoma. However, recently Ezh2 has also been found to be mutated/inactivated in other forms of cancer, suggesting a highly context-dependent role as either an oncogene or tumor suppressor. An outstanding question is how to identify among the many Pc-G bound genes the cancer-relevant ones. Hereto we have recently successfully combined stringent ChIP-seq with custom shRNAi library screening in in vivo models for glioblastoma. As Ezh2 is associated with poor prognosis and metastasis in many cancer settings there is an increasing interest for development of selective Ezh2 inhibitors as potential new ways for epigenetic cancer therapy. We have developed conditional shRNAi inhibition in mouse models for aggressive glioma to study the effects of Ezh2 inhibition on tumor initiation and maintenance. Whereas initial tumor regression upon Ezh2 inhibition was observed in vivo, prolonged Ezh2 inhibition caused unexpected profound changes in tumor plasticity, differentiation status with important consequences for tumor progression and treatment options, which will be discussed.

Selected references:

1. Sophia W.M. Bruggeman, Danielle Hulsman, Ellen Tanger, Tessa Buckle, Marleen Blom, John Zevenhoven, Olaf van Tellingen and Maarten van Lohuizen. Bmi1 controls tumor development in an Ink4a/Arf-independent manner in a mouse model for glioma. Cancer Cell 2007, 12, 328-341.

2. Gargiulo G, Cesaroni M, Serresi M, de Vries N, Hulsman D, Bruggeman SW, Lancini C, van Lohuizen M. In vivo RNAi screen for BMI1 targets identifies TGF-β/BMP-ER stress pathways as key regulators of neural- and malignant glioma-stem cell homeostasis. Cancer Cell. 2013 May 13;23(5):660-76

Citation Format: Maarten van Lohuizen. Unexpected results of prolonged EZH2 inhibition in an in vivo model for glioblastoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr SY35-01. doi:10.1158/1538-7445.AM2014-SY35-01
Abstract SY35-03: Novel anti-tumor activity of targeted LSD1 inhibition
Authors: Kruger Ryan G.
Published: May 2015

Lysine specific demethylase 1 (LSD1) is a histone H3K4me1/2 demethylase found in various transcriptional co-repressor complexes. These complexes include Histone Deacetylases (HDAC1/2) and Co-Repressor for Element-1-Silencing Transcription factor (CoREST). LSD1 mediated H3K4 demethylation can result in a repressive chromatin environment that silences gene expression and has been shown to play a role in development. LSD1 can interact with pluripotency factors in human embryonic stem cells and is essential for decommissioning enhancers in stem cell differentiation. Beyond embryonic settings, LSD1 is also critical for hematopoietic differentiation. LSD1 dysregulation plays a key role in cancer and LSD1 is overexpressed in multiple tumor types, including acute myeloid leukemia (AML). Recent literature suggests inhibition of LSD1 reactivates the all-trans retinoic acid differentiation pathway in AML. Together, these observations suggest LSD1 is an important regulator of the epigenome that modulates gene expression through post-translational modification of histones and its presence in transcriptional complexes.

The current study describes the anti-tumor effects of a novel LSD1 inhibitor (GSK2879552). GSK2879552 is a potent, selective, mechanism-based irreversible inhibitor of LSD1 currently in clinical development. Screening of over 150 cancer cell lines revealed that while many tumor types appear resistant to LSD1 inhibition, specific tumor types were uniquely sensitive. For example, AML cells have a distinct requirement for LSD1, and LSD1 inhibition results in a prodifferentiation effect in this setting. Preclinical characterization of the anti-tumor activities of GSK2879552 both in vitro and in vivo in AML as well as the solid tumor setting will be discussed.

All studies were conducted in accordance with the GSK Policy on the Care, Welfare and Treatment of Laboratory Animals and were reviewed the Institutional Animal Care and Use Committee either at GSK or by the ethical review process at the institution where the work was performed.

Citation Format: Ryan G. Kruger. Novel anti-tumor activity of targeted LSD1 inhibition. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr SY35-03. doi:10.1158/1538-7445.AM2014-SY35-03
Abstract 12: Germline BRCA mutations in an unselected cohort of patients with pancreatic adenocarcinoma
Authors: Holter Spring , Borgida Ayelet , Dodd Anna , Narod Steven , Akbari Mohammad , Moore Malcolm , Gallinger Steven
Published: May 2015

This is the first prospective study to determine the frequency of BRCA1 and BRCA2 germline mutations in an unselected series of patients with pancreatic adenocarcinoma.

Patients with histologically or clinically confirmed pancreatic adenocarcinoma were approached at a single cancer centre to enroll in the IRB-approved Ontario Pancreas Cancer Study. Patients provided informed consent and cancer family history data was obtained. Blood was collected and analyzed by Sanger sequencing and MLPA for germline variants in BRCA1 and BRCA2. All predicted deleterious germline variants were confirmed by a clinical laboratory on an independent blood sample.

Pathogenic germline mutations were identified in 12/234 (5%) of unselected incident pancreatic adenocarcinomas. BRCA1 mutations accounted for 1.2% (3/234) and BRCA2 accounted for 3.8% (9/234) cases. For the cohort, average age of pancreatic adenocarcinoma diagnosis was 65 years (27-91) and 46% were female. Previous primary cancer was reported in 24% of cases and 12% were of Ashkenazi Jewish descent. A family history of breast and/or ovarian cancer was reported in 25% of cases; however, of these with a family history, 1/3 did not meet NCCN guidelines to warrant germline BRCA analysis. Pancreatic cancer in another relative was reported in 12% of cases. A personal history of a previous primary cancer diagnosis and a family history of breast and/or ovarian cancer were significantly associated with germline BRCA mutations.

Previous studies of BRCA mutations in pancreatic adenocarcinoma have been limited to retrospective case series and incomplete germline analysis. Our study shows that germline BRCA mutations account for a significant proportion of pancreatic adenocarcinoma, regardless of family history of breast and ovarian cancer. Increased identification of patients with germline BRCA mutations and pancreatic adenocarcinoma may allow for tailored chemotherapy through the use of platinum agents or PARP inhibitors.

Citation Format: Spring Holter, Ayelet Borgida, Anna Dodd, Steven Narod, Mohammad Akbari, Malcolm Moore, Steven Gallinger. Germline BRCA mutations in an unselected cohort of patients with pancreatic adenocarcinoma. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Susceptibility and Cancer Susceptibility Syndromes; Jan 29-Feb 1, 2014; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(23 Suppl):Abstract nr 12. doi:10.1158/1538-7445.CANSUSC14-12
Abstract 18: Molecular characterization of Brazilian patients suspected for Lynch syndrome
Authors: Silva Felipe C. , Torrezan Giovana T. , Figueiredo Márcia CP , Ferreira Jose Roberto O. , Santos Érika M. , Nakagawa Wilson T. , Aguiar-Junior Samuel , Rossi Benedito M. , Ferreira Fabio O. , Carraro Dirce M.
Published: May 2015

Lynch syndrome (LS), former known as Hereditary Non Polyposis Colorectal cancer (HNPCC), accounts for 3-5% of all colorectal cancers (CRC) and is inherited in an autossomal dominant fashion. This syndrome is characterized by early CRC onset, high incidence of tumors in the ascending colon, excess of synchronous and metachronous tumors, and accelerated transition adenoma-carcinoma (2-3 years). Nowadays, LS is regarded of patients who carry deleterious germline mutations in one of the five Mismatch repair genes, such as MutL homolog 1 (MLH1), MutS homolog 2 (MSH2), MutS homolog 6 (MSH6), post-meiotic segregation increased 1 (PMS1) or post-meiotic segregation increased 2 (PMS2). In order to characterize Brazilian patients suspect for LS, we assessed the frequency of germline point mutations in MSH6, PMS1 and PMS2 in patients negative for point mutations in MLH1 and MSH2 by capillary sequencing. We also assessed chromosomal deletions in MLH1 and MSH2 and MSH6 generating a complete characterization of MMR genes. The analysis of the five MMR genes revealed 46 carriers of pathogenic mutations, including 25 in MSH2 (54%), 16 in MLH1 (35%), 4 in MSH6 (9%) and one in PMS2 (2%) gene In addition, from the 70 negative patients, we selected one mutation negative family that met the stringent Amsterdam criteria (AC) for whole exome sequencing using the SOLID platform. For this family, we selected 5 close blood relatives, including 3 affected and 2 unaffected individuals in order to facilitate the identification of new susceptibility genes with autosomal dominant pattern. The results revealed two candidate genes, c-KIT and WDR27 that segregated with the disease. Additional analysis are under evaluation.

Citation Format: Felipe C. Silva, Giovana T. Torrezan, Márcia CP Figueiredo, Jose Roberto O. Ferreira, Érika M. Santos, Wilson T. Nakagawa, Samuel Aguiar-Junior, Benedito M. Rossi, Fabio O. Ferreira, Dirce M. Carraro. Molecular characterization of Brazilian patients suspected for Lynch syndrome. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Susceptibility and Cancer Susceptibility Syndromes; Jan 29-Feb 1, 2014; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(23 Suppl):Abstract nr 18. doi:10.1158/1538-7445.CANSUSC14-18
Abstract 19: Novel HIF2A mutations disrupting oxygen sensing lead to a new syndrome of multiple paragangliomas and somatostatinomas associated with polycythemia
Authors: Yang Chunzhang , Pacak Karel , Zhuang Zhengping
Published: May 2015

Hypoxia inducible factors (HIFs) control the cellular response to hypoxia and when dysregulated, contribute to tumorigenesis. We identified novel somatic mutations in HIF2A in patients with multiple paragangliomas and somatostatinomas associated with polycythemia, representing a new syndrome found predominantly in female patients. Mutations in HIF2A resulted in an amino acid substitution in the evolutionarily conserved oxygen-dependent degradation (ODD) domain and were found to uniquely disrupt the HIF-2α hydroxylation site recognized by prolyl hydroxylase domain-2 containing protein (PHD2). Disruption of HIF-2α hydroxylation resulted in the stabilization of HIF-2α and increased expression of hypoxia-related genes, dysregulated hematopoiesis, and neuroendocrine tumor formation. These results show for the first time the role of HIF-2α somatic mutations in cancer pathogenesis.

Citation Format: Chunzhang Yang, Karel Pacak, Zhengping Zhuang. Novel HIF2A mutations disrupting oxygen sensing lead to a new syndrome of multiple paragangliomas and somatostatinomas associated with polycythemia. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Susceptibility and Cancer Susceptibility Syndromes; Jan 29-Feb 1, 2014; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(23 Suppl):Abstract nr 19. doi:10.1158/1538-7445.CANSUSC14-19
Abstract 30: Intermittent treatment with the PARP inhibitor olaparib delays tumor development in BRCA1-deficient mice
Authors: Liby Karen T. , To Ciric
Published: May 2015

Women with inherited BRCA gene mutations are at extremely high risk for developing breast cancer. Although these high risk patients are ideal candidates for an effective chemoprevention regimen, “watchful waiting” or bilateral prophylactic mastectomy are the only currently available options. BRCA proteins are required for repairing double strand DNA breaks through homologous recombination. In BRCA-deficient cells, DNA is repaired by base excision repair, which requires a PARP protein. PARP inhibitors can selectively induce apoptosis in BRCA-deficient cells, without affecting normal cells, by blocking the only DNA repair pathway available to these cells. Various PARP inhibitors are being tested in the clinic in women with BRCA mutations, and if effective, these drugs might also be useful for chemoprevention. When fed continuously in diet, the PARP inhibitor olaparib (200 mg/kg diet) significantly delayed tumor development by 6.5 weeks in the aggressive Brca1Co/Co;MMTV-Cre;p53+/- mouse model. An intermittent schedule was then tested; olaparib was given for 2 week cycles in order to induce apoptosis in premalignant cells followed by 4 week rest periods in an attempt to reduce drug toxicity. Intermittent therapy with olaparib was nearly as effective as the continuous feeding protocol and increased the age of initial tumor onset to 35.6 ± 1.0 wks compared to 29.9 ± 1.1 wks in the control group (P < 0.001; n = 18-19 mice/group). Olaparib also decreased proliferation and induced apoptosis in the mammary glands of mice without palpable tumors. In summary, these studies demonstrate that the PARP inhibitor olaparib is effective for delaying tumor development in BRCA1-deficient mice and suggest that intermittent therapy with this drug might be useful for chemoprevention in high risk women with BRCA mutations.

Supported by Susan G. Komen for the Cure and the Breast Cancer Research Foundation

Citation Format: Karen T. Liby, Ciric To. Intermittent treatment with the PARP inhibitor olaparib delays tumor development in BRCA1-deficient mice. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Susceptibility and Cancer Susceptibility Syndromes; Jan 29-Feb 1, 2014; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(23 Suppl):Abstract nr 30. doi:10.1158/1538-7445.CANSUSC14-30
Abstract 44: Leukemia-associated DNMT3A R882 mutations and their role in anthracycline-induced DNA damage response and therapeutic resistance
Authors: Guryanova Olga A. , Shank Kaitlyn , Luciani Luisa , Loizou Evangelia , Keller Matthew D. , Weinstein Abby R. , Abdel-Wahab Omar , Mukherjee Siddhartha , Nimer Stephen S. , Levine Ross L.
Published: May 2015

Despite significant advances in cancer research and treatment, therapeutic resistance remains a major obstacle for achieving stable remission in cancer patients. Acute myeloid leukemia (AML) is no exception, and most AML patients develop resistance to chemotherapy/targeted therapies, which results in disease relapse and progression. Recurrent mutations in the DNA methyltransferase 3A (DNMT3A) gene have been identified in 20-30% of AML cases and are predictive of unfavorable prognosis in patients treated with standard anti-leukemic regimens. In addition, DNMT3A-mutant AMLs appear to be relatively refractory to anthracycline family chemotherapeutics, such as daunorubicin. Half of all DNMT3A mutations affect amino acid residue R882, and recent work has shown that these mutants display decreased enzymatic activity and aberrant binding properties. In addition, previous studies have shown that wild-type DNMT3A functions as a pro-apoptotic switch in response to genotoxic stress induced by another anthracycline doxorubicin. We propose that mutant DNMT3A protects cells from apoptosis in response to DNA damage by altering molecular machinery involved in DNA-damage sensing, response and/or repair, through DNA methylation-dependent or independent mechanisms. Specifically, our data show that mutant DNMT3A affects recruitment of DNA repair proteins to chromatin, including aberrant distribution of homologous recombination marker RAD51. We are currently investigating molecular changes in DNA damage response in DNMT3A-mutant cells in vitro and ex vivo, and leukemogenic potential of the mutant Dnmt3a allele in vivo, whether alone or in combination with other cooperating oncogenes.

Citation Format: Olga A. Guryanova, Kaitlyn Shank, Luisa Luciani, Evangelia Loizou, Matthew D. Keller, Abby R. Weinstein, Omar Abdel-Wahab, Siddhartha Mukherjee, Stephen S. Nimer, Ross L. Levine. Leukemia-associated DNMT3A R882 mutations and their role in anthracycline-induced DNA damage response and therapeutic resistance. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Susceptibility and Cancer Susceptibility Syndromes; Jan 29-Feb 1, 2014; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(23 Suppl):Abstract nr 44. doi:10.1158/1538-7445.CANSUSC14-44
Abstract IA01: Gene regulatory network approaches to interpreting breast cancer GWAS results
Authors: Ponder Bruce A. J. , Meyer Kerstin , Fletcher Michael , Markowetz Florian , Santiago Ines de , Castro Mauro
Published: May 2015

Six years after the publication of the first breast cancer GWAS, skepticism is expressed about the usefulness of the results. The GWAS loci identified to date explain only a minority of the estimated genetic variance, and the risks conferred by even the strongest individual variants are small. Classical biochemical pathway approaches to elucidating mechanism have had modest success.

I will argue that an attempt to examine the combined effects by common and rare variants and their interactions through analysis based on gene regulatory networks may yield new and useful information. Although still speculative, I will present initial data that provide support for this approach.

Citation Format: Bruce A. J. Ponder, Kerstin Meyer, Michael Fletcher, Florian Markowetz, Ines de Santiago, Mauro Castro. Gene regulatory network approaches to interpreting breast cancer GWAS results. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Susceptibility and Cancer Susceptibility Syndromes; Jan 29-Feb 1, 2014; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(23 Suppl):Abstract nr IA01. doi:10.1158/1538-7445.CANSUSC14-IA01
Abstract IA05: Fanconi's anemia: Emerging therapeutic opportunities
Authors: Grompe Markus , Postlethwait John , D'Andrea Alan , Olson Susan , Zhang Qingshuo , Bagby Grover
Published: May 2015

Fanconi's anemia (FA) is a genetically heterogeneous inherited disorder characterized by bone marrow failure, birth defects and cancer susceptibility. At the cellular level, FA features hypersensitivity to DNA cross-linking agents, cell cycle abnormalities and abnormal responses to cytokines. Therapy for the hematopoietic defects of FA has consisted of supportive care, stem cell transplantation and administration of androgens such as oxymetholone. Unfortunately, even successfully transplanted FA patients have a very high risk for subsequent solid tumors, especially squamous cell carcinomas of oropharyngeal and urogenital areas.

The pharmacological treatment of FA has been unchanged for several decades and for this reason our group has embarked on systematic search for small molecule therapeutics that could benefit FA patients. This effort has been made possible by the cloning of 16 FA genes and biochemical insights into the function of FA proteins. Mouse models, zebra fish models and FA patient cell lines, including IPSC are available for screening and validation.

The specific goals of small molecule interventions are to delay or prevent hematopoietic failure and also to delay or prevent carcinogenesis.

To date we have shown that the superoxide dismutase mimetic drug Tempol can significantly delay tumor formation in FA mice. Similarly, resveratrol clearly improved hematopoiesis in the same model.

Medium throughput screens have revealed numerous new molecules which ameliorate the FA phenotypes of cells, mice and zebrafish respectively. Using genetic approaches we also have identified the p53 pathway as a therapeutic target in FA.

These therapeutic opportunities and progress in FA small molecule screening will be discussed.

Citation Format: Markus Grompe, John Postlethwait, Alan D'Andrea, Susan Olson, Qingshuo Zhang, Grover Bagby. Fanconi's anemia: Emerging therapeutic opportunities. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Susceptibility and Cancer Susceptibility Syndromes; Jan 29-Feb 1, 2014; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(23 Suppl):Abstract nr IA05. doi:10.1158/1538-7445.CANSUSC14-IA05
Abstract IA08: PTEN and PI3K signaling in brain development and disease
Authors: Baker Suzanne J.
Published: May 2015

Virtually all adult glioblastomas contain somatic mutations resulting in elevated activity of the receptor tyrosine kinase (RTK)/Ras/PI3K signaling axis, including common loss of function mutations in PTEN, activating mutations in PIK3CA encoding p110α, the catalytic subunit of PI3Kα, or mutations in PIK3R1, encoding p85α, the regulatory subunit of PI3K. Despite an important role in sporadic glioblastoma, germline PTEN mutations do not confer an increased genetic susceptibility to brain tumors. However, inherited mutation of PTEN is associated with macrocephaly and neurological abnormalities including seizures, ataxia, autism and Lhermitte-Duclos disease. Mouse models further demonstrate that PTEN plays an essential role in development, homeostasis, and tumor suppression in the mammalian brain. Recently, germline or somatic mutations in multiple components of the PI3K signaling pathway were identified in human megalencephaly syndromes without apparent association with cancer predisposition, including mutations in PIK3CA, AKT3, PIK3R2, and MTOR. Mouse models that demonstrate the varying contributions of PI3K pathway members in brain development or tumorigenesis, and show context-dependent roles for PI3K signaling will be discussed.

Citation Format: Suzanne J. Baker. PTEN and PI3K signaling in brain development and disease. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Susceptibility and Cancer Susceptibility Syndromes; Jan 29-Feb 1, 2014; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(23 Suppl):Abstract nr IA08. doi:10.1158/1538-7445.CANSUSC14-IA08
Abstract IA10: Li-Fraumeni syndrome: p53 and beyond
Authors: Wasserman Jonathan , Villani Anita , Samuel Nardin , Merino Diana , Novokmet Ana , Pienkowska Margaret , IdSaid Badr , Malkin David
Published: May 2015

Germline TP53 mutations are observed in ∼80% of patients with Li-Fraumeni syndrome (LFS) and a lesser frequency of patients meeting the revised Chompret criteria. A variety of studies are being conducted exploring the role of genetic modifiers on p53 function and their impact in refining the genotype:phenotype correlation of the TP53:LFS relationship. In this presentation, four classical pediatric-onset LFS tumors (choroid plexus carcinoma, medulloblastoma, adrenocortical carcinoma and rhabdomyosarcoma) will be used as examples to demonstrate the molecular nuances of this complex relationship. A spectrum of findings will be outlined that support the notion that presence of a germline TP53 mutation in the context of different modifying effects of intragenic TP53 polymorphism as well as variants in genes and proteins that play important roles in the p53 network confers certain biological features to the presentation of these tumors. Biological mechanisms will be discussed and strategies for early cancer detection will be presented.

Citation Format: Jonathan Wasserman, Anita Villani, Nardin Samuel, Diana Merino, Ana Novokmet, Margaret Pienkowska, Badr IdSaid, David Malkin. Li-Fraumeni syndrome: p53 and beyond. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Susceptibility and Cancer Susceptibility Syndromes; Jan 29-Feb 1, 2014; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(23 Suppl):Abstract nr IA10. doi:10.1158/1538-7445.CANSUSC14-IA10
Abstract IA19: Dyskeratosis congenita and related syndromes
Authors: Dokal Inderjeet
Published: May 2015

Dyskeratosis Congenita (DC) is a heterogeneous multi-system syndrome exhibiting marked clinical and genetic heterogeneity. In its classical form it is characterized by mucocutaneous abnormalities (abnormal skin pigmentation, nail dystrophy, leucoplakia), bone marrow failure and a high predisposition to malignancy (hematological and non-hematological). Bone marrow failure is the principal cause of mortality and patients display features of premature aging (including early dental loss, premature greying and osteoporosis).

Studies over the last 15 years have led to significant advances with ten DC genes (DKC1, TERC, TERT, NOP10, NHP2, TINF2, USB1, TCAB1, CTC1 and RTEL1) having been characterized. Nine of these are important in telomere maintenance. DC is therefore principally a disease of defective telomere maintenance and patients usually have very short/ and or abnormal telomeres.

The genetic advances have also led to the unification of DC with a number of other disorders. This includes the severe multi-system disorders Hoyeraal-Hreidarsson and Revesz syndromes as well as a subset of patients with aplastic anemia, myelodysplasia, leukemia, liver disease and idiopathic pulmonary fibrosis. This wide spectrum of diseases ranging from classical DC to aplastic anemia can be regarded as disorders of defective telomere maintenance - “the telomereopathies”.

These advances have increased our understanding of several human diseases (including genetic predisposition to subtypes of cancer) and highlighted the importance of telomere maintenance in human biology. They are also facilitating diagnosis (especially when presentation is atypical) and management. Correct early diagnosis is important as bone marrow failure associated with this group of disorders is unlikely to respond to immunosuppressive agents and is more likely to respond to anabolic steroids such as oxymetholone. For patients who are unresponsive to anabolic steroids allogeneic hematopoietic stem cell transplantation using fludarabine based low intensity protocols is producing encouraging results.

Citation Format: Inderjeet Dokal. Dyskeratosis congenita and related syndromes. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Susceptibility and Cancer Susceptibility Syndromes; Jan 29-Feb 1, 2014; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(23 Suppl):Abstract nr IA19. doi:10.1158/1538-7445.CANSUSC14-IA19
Abstract IA23: The BRCA1 tumor suppressor network
Authors: Greenberg Roger A.
Published: May 2015

BRCA1 is an essential component of multiple distinct protein complexes that are dedicated to DNA damage recognition and repair. Germline heterozygous mutations to genes encoding multiple BRCA associated proteins result in cancer susceptibility, while biallelic mutations lead to developmental abnormalities, cancer predisposition, and systemic hypersensitivity to chemotherapy. BRCA1 associates with the RAP80 complex to recognize lysine63-linked ubiquitin chains at DNA damage sites. Three members of the RAP80 complex are mutated in hereditary breast cancer, implicating ubiquitin recognition as a bona fide component of BRCA1 dependent tumor suppression. This presentation will describe in vivo interactions between BRCA1 associated DNA damage site ubiquitin recognition and other protein complexes that are dedicated to homologous recombination mediated DNA repair to S-phase. Relevance to cancer etiology and response to therapy will be discussed.

Citation Format: Roger A. Greenberg. The BRCA1 tumor suppressor network. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Susceptibility and Cancer Susceptibility Syndromes; Jan 29-Feb 1, 2014; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(23 Suppl):Abstract nr IA23. doi:10.1158/1538-7445.CANSUSC14-IA23
Abstract A03: Effectiveness of melatonin on the epithelial mesenchymal transition after induction with transforming growth factor beta (TGF-β)
Authors: Gonçalves Naiane do Nascimento , Ferreira Lívia Carvalho , Lopes Juliana Ramos , Maschio Larissa Bazela , Moschetta Marina Gobbe , Gelaleti Gabriela Bottaro , Martins Gustavo Rodrigues , Zuccari Debora Aparecida Pires de Campos
Published: May 2015

Background: The mammary tumors are the most frequent in women in Brazil and worldwide. The high mortality rate in breast cancer is mainly due to invasiveness and metastatic. The metastatic process involves a mechanism called epithelial-mesenchymal transition (EMT). The EMT mechanism can be induced by growth factors such as transforming growth factor beta (TGF-β), which alters the epithelial phenotype (E-cadherin) to a mesenchymal phenotype (n-caderina/vimentina). Studies have shown significant importance of the epithelial mesenchymal transition in breast cancer, which makes the study of new therapeutic agents that act in the process, very important. Melatonin, a hormone naturally secreted by the pineal gland, has shown oncostatic properties. For these reasons, the aim of this study was to evaluate the anti-metastatic potential of melatonin by the epithelial mesenchymal transition induced by TGF-β in breast cancer cell line. Methods: The breast cancer cell line MCF-7 was cultured at 37 ° C and 5% CO2 in DMEM High Glucose culture medium. Once established, the best concentration of TGF-β (0.5 ng / mL) to induce epithelial mesenchymal transition the cells were divided into four groups (Group I - Control, Group II - TGF-β, Group III - Melatonin and Group IV - TGF- β + Melatonin) to evaluate the protein expression of E-cadherin, N-cadherin and vimentin by immunocytochemistry. Quantitation of immunoreactivity was performed by densitometry (ImageJ software). The results were compared by ANOVA followed by Bonferroni. Results: The results showed that there were statistically significant increased protein e-cadherin in cells treated with melatonin (P < 0.05) when compared to cells treated with TGF-β. Furthermore, immunostaining of proteins N-cadherin and vimentin was lower in cells treated with TGF-B + melatonin (P < 0.05) compared to cells treated only with TGF-β. Conclusion: Melatonin interfered in the expression of proteins related to epithelial mesenchymal transition after induction with TGF-B which may suggested a possible anti-metastatic role of this hormone.

Citation Format: Naiane do Nascimento Gonçalves, Lívia Carvalho Ferreira, Juliana Ramos Lopes, Larissa Bazela Maschio, Marina Gobbe Moschetta, Gabriela Bottaro Gelaleti, Gustavo Rodrigues Martins, Debora Aparecida Pires de Campos Zuccari. Effectiveness of melatonin on the epithelial mesenchymal transition after induction with transforming growth factor beta (TGF-β). [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr A03. doi:10.1158/1538-7445.CHTME14-A03
Abstract A04: Endothelial FAK activity controls vascular permeability and tumor metastasis
Authors: Jean Christine , Chen Xiao Lei , Tancioni Isabelle , Uryu Sean , Lawson Christine , Miller Nichol , Turowski Patric , Dejana Elisabetta , Weis Sara , Cheresh David , Schlaepfer David D.
Published: May 2015

Tumor spread remains a primary cause of cancer mortality. Focal adhesion kinase (FAK) is a cytoplasmic tyrosine kinase co-activated by integrin and growth factor receptors in the control of vascular permeability. As FAK inhibitors are being tested in clinical trials, it is important to determine whether FAK signaling plays distinct roles in tumor versus stromal cell biology. Herein, we elucidate a new mechanism for endothelial cell (EC) FAK activity in the regulation of blood vessel barrier integrity and the passage of tumor cells through an EC barrier. We show that vascular endothelial cadherin (VEC) tyrosine (Y) 658 is phosphorylated by FAK in tumor-associated ECs. Conditional kinase-dead FAK knockin within ECs inhibited recombinant vascular endothelial growth factor (VEGF-A) and tumor-induced VEC Y658 phosphorylation in vivo. Adherence of VEGF-expressing tumor cells to ECs triggered FAK-dependent VEC Y658 phosphorylation. Both FAK inhibition and VEC Y658F mutation within ECs prevented VEGF-initiated paracellular permeability and tumor cell transmigration across EC barriers. In mice, EC FAK inhibition prevented VEGF-dependent tumor cell extravasation and melanoma dermal to lung metastasis without affecting primary tumor growth. Although it is known that Src tyrosine kinase activity is important in controlling VEC tyrosine phosphorylation downstream of VEGF, we find that pharmacological Src inhibition prevents FAK activation. Moreover, FAK inhibition prevents both Src and FAK translocation to EC adherens junctions, but does not alter Src activation. Together, these results identify EC FAK as a key intermediate between Src and the regulation of EC barrier function controlling tumor metastasis.

Citation Format: Christine Jean, Xiao Lei Chen, Isabelle Tancioni, Sean Uryu, Christine Lawson, Nichol Miller, Patric Turowski, Elisabetta Dejana, Sara Weis, David Cheresh, David D. Schlaepfer. Endothelial FAK activity controls vascular permeability and tumor metastasis. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr A04. doi:10.1158/1538-7445.CHTME14-A04
Abstract A23: ALK activity in macrophages drives metastasis in murine models of breast cancer
Authors: Lynn Kristi D. , Brekken Rolf A.
Published: May 2015

VEGF-induced angiogenesis and macrophages contribute directly to metastasis, the leading cause of breast cancer related mortality. VEGF is a major driver of angiogenesis, yet its targeted inhibition is often ineffective at controlling metastases. In contrast, pathways that contribute to a pro-metastatic macrophage phenotype are unclear and pharmacological strategies to inhibit pro-metastatic activity are lacking. In this study, we illustrate that anti-VEGF therapy modulates PTN expression in multiple mouse models of breast cancer. Once expressed, PTN induces the expression of VEGFR2 on macrophages and promotes an anti-inflammatory, pro-metastatic macrophage phenotype. This phenomenon is dependent on ALK signaling, as inhibition with the small molecule receptor tyrosine kinase inhibitor crizotinib (Xalkori, Pfizer), which targets ALK, or ALK siRNA is sufficient to reverse PTN-induced VEGFR2 and anti-inflammatory macrophage marker expression. Importantly, phosphorylated ALK and VEGFR2 positive macrophages were detected in tumor but not normal breast tissue from patients. Furthermore, inhibition of ALK signaling in macrophages blunted metastasis but had no effect on primary MMTV-PyMT tumors; while blockade of VEGF slowed primary tumor growth without effect on metastatic burden. Combined inhibition of ALK and VEGF activity showed potent anti-tumor and anti-metastatic activity in animals with disseminated disease. Collectively, our data document novel markers of pro-metastatic macrophages and reveal how macrophage phenotype can be manipulated to suppress breast cancer progression.

Citation Format: Kristi D. Lynn, Rolf A. Brekken. ALK activity in macrophages drives metastasis in murine models of breast cancer. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr A23. doi:10.1158/1538-7445.CHTME14-A23
Abstract A28: Impact of macrophage function on the efficacy of radiation therapy
Authors: Shiao Stephen L. , DeNardo David G. , Faddegon Bruce A. , Underhill David M. , Park Catherine C. , Coussens Lisa M.
Published: May 2015

In patients with locally advanced breast cancer, radiation therapy (RT) and chemotherapy following surgery has been a mainstay of treatment for breast cancer with demonstrated survival advantage in numerous randomized trials. However, despite recent advances in treatment, many women still ultimately succumb to this disease highlighting the need to improve our therapeutic options. Previous work from other groups demonstrated that the therapeutic effects of RT depend in part on activation of the immune system, but little is known about the details of this activation. To address this, we explored the effects of RT on the immune microenvironment in a syngeneic orthotopic murine transplantation model of breast cancer and found that 7 days following RT tumors had significantly increased numbers of CD11b+ macrophages compared to untreated tumors. When we depleted these macrophages using a CSF1 inhibitor or CSF1 blocking Ab following RT we found significantly delayed tumor growth compared to RT alone. Tumor-associated macrophages (TAMs) are key orchestrators of the tumor microenvironment and can be either classically-activated expressing cytotoxic molecules leading to tumor cell death (“anti-tumor”) or alternatively-activated in which they secrete proangiogenic, prosurvival, and proinvasive factors that foster tumor progression (“pro-tumor”). Given the delayed growth when TAMs were depleted following RT, we hypothesized that the infiltrating TAMs are predominantly of the pro-tumor phenotype and that a milieu that favors an anti-tumor phenotype would enhance the effect of RT. We tested this hypothesis using a blocking antibody against IL-4, the predominant cytokine which drives the alternatively-activated phenotype, and we observed significantly reduced tumor growth in mice treated with the combination of RT and IL-4 blockade compared to mice treated with either agent alone. These studies indicate that infiltrating macrophages following RT have a protumor function, and that conversion of these macrophages to a cytotoxic phenotype may improve the efficacy of RT.

Citation Format: Stephen L. Shiao, David G. DeNardo, Bruce A. Faddegon, David M. Underhill, Catherine C. Park, Lisa M. Coussens. Impact of macrophage function on the efficacy of radiation therapy. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr A28. doi:10.1158/1538-7445.CHTME14-A28
Abstract A30: MKP-1 negatively regulates Il-1beta in the oral tumor microenvironment
Authors: Zhang Xiaoyi , Yu Hong , Kirkwood Keith L.
Published: May 2015

Head and neck cancer accounts for approximately 6% of diagnosed malignancies in the United States, the most common form being head and neck squamous cell carcinoma (HNSCC). Cytokines and pro-inflammatory factors have been shown to play a critical role in various steps of malignant transformation, many of which are regulated by mitogen-activated protein kinases (MAPK). These kinases are negatively regulated by MAPK phosphatases (MKPs), the founding member of this class being mitogen-activated protein kinase phosphatase-1 (MKP-1). MKP-1 is often over-expressed in early stages of epithelial malignancies with levels of expression falling progressively in tumors of higher histological grade. As MKP-1 is a crucial negative regulator of innate immunity, we hypothesized MKP-1 inhibits tumor-promoting inflammation in the HNSCC microenvironment. MKP-1 deficient animals treated with 4-nitroquinoline 1-oxide to induce HNSCC formation showed a significant increase in tumor development, characterized by tumor onset, size, histological grade, and inflammation. Tumor tissues expressed increased levels of multiple inflammatory cytokines and chemokines by qPCR and altered MAPK activity by immunoblot and immunohistochemistry. In particular, Il-1beta was significantly increased in MKP-1 deficient tumors as well as primary bone marrow-derived macrophages. These data suggest MKP-1 inhibits oral cancer progression by regulating Il-1beta expression. Elucidating the regulation of this inflammatory mediator in the tumor microenvironment may reveal critical tumor suppressive interactions mediated by MKP-1 that are lost during cancer progression.

Citation Format: Xiaoyi Zhang, Hong Yu, Keith L. Kirkwood. MKP-1 negatively regulates Il-1beta in the oral tumor microenvironment. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr A30. doi:10.1158/1538-7445.CHTME14-A30
Abstract A41: Hypoxia-dependent modification of collagen networks promotes sarcoma metastasis
Authors: Eisinger-Mathason T.S. Karin , Zhang Minsi , Qiong Qiu , Skuli Nicolas , Nakazawa Michael S. , Karakasheva Tatiana , Mucaj Vera , Shay Jessica E.S. , Stangenberg Lars , Pure Ellen , Yoon Sam S. , Kirsch David G. , Simon M. Celeste
Published: May 2015

Intratumoral hypoxia and expression of Hypoxia Inducible Factor 1α (HIF1α) correlate with metastasis and poor survival in sarcoma patients. We demonstrate here that hypoxia controls sarcoma metastasis through a novel mechanism wherein HIF1α enhances expression of the intracellular enzyme procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2 (PLOD2). We show that loss of HIF1α or PLOD2 expression disrupts collagen modification, cell migration and pulmonary metastasis (but not primary tumor growth) in allograft and autochthonous LSL-KrasG12D/+; Trp53fl/fl murine sarcoma models. Biochemical analyses revealed that overexpression of HIF1α and PLOD2 in sarcoma cells alters collagen structure and organization. The increase in lysyl hydroxylation and concomitant loss of prolyl hydroxylation, promotes adherence of tumor cells, collagen-associated migration and tumor cell dissemination. Furthermore, ectopic PLOD2 expression restores migration and metastatic potential in HIF1α-deficient tumors, and analysis of human sarcomas reveal elevated HIF1α and PLOD2 expression in metastatic primary lesions. Pharmacological inhibition of PLOD enzymatic activity suppresses metastases. Collectively, these data indicate that HIF1α controls sarcoma metastasis through PLOD2-dependent collagen modification and organization in primary tumors. We conclude that PLOD2 is a novel therapeutic target in sarcomas and successful inhibition of this enzyme may reduce tumor cell dissemination.

Citation Format: T.S. Karin Eisinger-Mathason, Minsi Zhang, Qiu Qiong, Nicolas Skuli, Michael S. Nakazawa, Tatiana Karakasheva, Vera Mucaj, Jessica E.S. Shay, Lars Stangenberg, Ellen Pure, Sam S. Yoon, David G. Kirsch, M. Celeste Simon. Hypoxia-dependent modification of collagen networks promotes sarcoma metastasis. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr A41. doi:10.1158/1538-7445.CHTME14-A41
Abstract A52: Paracrine apoptotic effect of the tumor suppressor p53 is mediated by secreted Par-4
Authors: Shrestha-Bhattarai Tripti , Burikhanov Ravshan , Hebbar Nikhil , Qiu Shirley , Zhao Yanming , Zambetti Gerard P. , Rangnekar Vivek M.
Published: May 2015

The guardian of the genome, p53, is mutated or functionally inactivated in a majority of human cancers. However, p53 in normal cells is intact and functional. In the present study, we tested the potential of wild-type p53 in normal tissues to inhibit the growth of p53-deficient cancer cells. Co-culture experiments of normal fibroblasts with cancer cells revealed that specific activation of p53 in normal fibroblasts selectively induced apoptosis in p53-deficient cancer cells. Moreover, this paracrine apoptotic effect of p53 was attributed to an enhanced secretion of the tumor suppressor Par-4 in response to p53 activation. Mechanistically, p53 represses the expression of UACA, a binding partner of Par-4, by directly binding to its signature motif in the UACA gene. Down-regulation of UACA expression liberates Par-4 from sequestration, and thus induces its secretion. Consistent with our cell culture studies, animal experiments also show that activation of p53 results in an elevation of systemic Par-4 levels in p53+/+ mice, which can induce apoptosis in p53-deficient cancer cells in ex vivo experiments. By contrast, p53 activators failed to induce this paracrine effect in p53-/- or Par-4-/- mice. Thus, by activating wild-type p53, normal cells can be empowered to inhibit tumor growth, progression, and metastasis.

Citation Format: Tripti Shrestha-Bhattarai, Ravshan Burikhanov, Nikhil Hebbar, Shirley Qiu, Yanming Zhao, Gerard P. Zambetti, Vivek M. Rangnekar. Paracrine apoptotic effect of the tumor suppressor p53 is mediated by secreted Par-4. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr A52. doi:10.1158/1538-7445.CHTME14-A52
Abstract A58: Characterized herbal extract of Wedelia chinensis suppresses prostate cancer growth and metastasis by targeting multiple intrinsic pathways and modulating immune cells
Authors: Tsai Chin-Hsien , Tzeng Sheue-Fen , Hsiao Pei-Wen
Published: May 2015

We previously demonstrated that the principal active compounds (wedelolectone, luteolin, and apigenin) in the ethanol extract of Wedelia chinensis synergistically inhibit human prostate carcinoma 22Rv1 cell growth and that this extract therefore has potential for use as a prostate cancer (PCa) therapy. Here, we developed a standardized preparation for a W. chinensis ethanol extract that is enriched in the principal active compounds. A comparison of the effect of herbal treatment, androgen ablation therapy, and a combination of the two on the development of androgen-dependent LNCaP tumors in a mouse model showed that the herbal extract alone decreased androgen-induced tumor growth and when in combination with androgen ablation therapy, resulted in more potent inhibition of both tumor growth and cancer metastasis. Our study demonstrated this herbal remedy simultaneously inhibited androgen receptor, NFκB and HER2/3-AKT signaling pathways to induce cell apoptosis. Importantly, our herbal remedy diminished androgen receptor overexpression and AKT activation induced by androgen ablation thus preventing castration-resistant PCa development. Moreover, the herbal remedy standing-alone curbed chemokine expression from hormone-refractory PC-3 tumor and consequently restrained the mobilization of CD11b+Gr1+ myeloid cells in tumor-bearing mice, which effectively inhibited PCa growth and metastasis. In conclusion, this standardized preparation of W. chinensis ethanol extract improved the outcome of PCa therapy either as an add-on to hormonal therapy for androgen-dependent disease or as a monotherapy for hormone-refractory disease.

Citation Format: Chin-Hsien Tsai, Sheue-Fen Tzeng, Pei-Wen Hsiao. Characterized herbal extract of Wedelia chinensis suppresses prostate cancer growth and metastasis by targeting multiple intrinsic pathways and modulating immune cells. [abstract]. In: Abstracts: AACR Special Conference on Cellular Heterogeneity in the Tumor Microenvironment; 2014 Feb 26-Mar 1; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2015;75(1 Suppl):Abstract nr A58. doi:10.1158/1538-7445.CHTME14-A58