bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract SY18-01: Alterations in metabolic pathways to support cancer cell proliferation
Authors: Vander Heiden Matthew G.
Published: June 2012

Unlike the majority of differentiated cells, many cancer cells metabolize glucose by aerobic glycolysis even in the presence of sufficient oxygen to support mitochondrial respiration. This phenomenon, also known as the Warburg effect, is characterized by increased glycolysis with lactate production and decreased oxidative phosphorylation. We have argued that aerobic glycolysis may be selected for by cancer cells to meet the distinct metabolic needs of proliferation. Unlike metabolism in differentiated cells, which is geared toward efficient ATP generation, the aerobic glycolysis observed in cancer cells appears to be adapted to facilitate the accumulation of biomass.

Our understanding of how cancer cells meet their metabolic needs is based primarily on studies of cultured cells, and nutrient conditions in vitro differ significantly from those seen by tumor cells in vivo. Our long-term objective is to develop a comprehensive understanding on how cell metabolism is altered to accommodate anabolic synthesis and support the growth of tumors in vivo. The M2 isoform of pyruvate kinase (PK-M2) promotes the metabolism of glucose by aerobic glycolysis, contributes to anabolic metabolism, and appears necessary for optimal tumor growth in vivo. Paradoxically, these consequences of PK-M2 isoform selection are associated with decreased pyruvate kinase enzyme activity. Experiments to test the hypothesis that decreased pyruvate kinase activity promotes anabolic metabolism and cell proliferation in vivo will be presented. This includes data generated using genetically engineered mouse cancer models and small molecule activators of PK-M2. Additionally, efforts to understand pyruvate kinase-mediated regulation of glycolysis in cancer cells will be discussed. Decreased pyruvate kinase activity in cancer cells is accompanied by an alternate regulation of glycolysis. This creates a branch point in glycolysis to divert 3-phosphoglycerate into the serine biosynthesis pathway, and this reorganization of metabolic flux appears to be is important for proliferation. In fact, in some cancers a substantial portion of the total glucose flux is directed to serine synthesis and additional genetic evidence will be presented to suggest that glucose flux into this pathway can promote cell transformation. Finally, the role of the tumor environment, and how this contributes to the reorganization of metabolic pathways to support anabolic metabolism will be discussed.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr SY18-01. doi:10.1158/1538-7445.AM2011-SY18-01
Abstract SY19-01: Identifying and overcoming immune barriers at the level of the tumor microenvironment
Authors: Gajewski Thomas Frank
Published: June 2012

Immunotherapeutic approaches for the treatment of melanoma, such as tumor antigen-based vaccines, can frequently boost immune responses as measured in the peripheral blood. However, clinical responses as measured by tumor shrinkage have been observed in only a minority of patients. This observation has prompted careful analysis of the tumor microenvironment to probe for biologic correlates to clinical response and also to identify mechanisms of tumor resistance. Patients with advanced melanoma treated on two different vaccine platforms had pretreatment tumor biopsies analyzed by Affymetrix gene expression profiling. Supervised hierarchical clustering was performed based on favorable or unfavorable clinical outcome. An expanded bank of tumors was also analyzed to increase the sample size and better understand gene patterns that segregate into subtypes. Two major categories of melanoma metastases have been observed. One subgroup of patients has an inflamed phenotype that includes expression of chemokines, T cell markers, and other immunoregulatory factors. Clinical responders to melanoma vaccines appear to fall within this subset. This group also contains the highest expression of negative regulatory factors, including PD-L1, IDO, and FoxP3, suggesting that these immune suppressive mechanisms may dominantly inhibit antitumor T cell function in those patients. In addition, absence of B7 expression suggests that classical T cell anergy also may be operational. Preclinical experiments have confirmed a critical role for all 4 of these mechanisms in limiting antitumor T cell efficacy in vivo, giving candidate treatment strategies for translation back into the clinic. These include IDO inhibitors, anti-PD-1 mAbs, and approaches to deplete CD25+ Tregs. A second subset of patients is represented by tumors which are noninflamed and lack chemokines for T cell recruitment. Therefore, a major barrier in these cases appears to be failed T cell migration into tumor sites. Experimental strategies to augment T cell migration can have important antitumor effects in preclinical models. Finally, the presence of inflammatory factors was associated with a type I IFN transcriptional signature, and murine experimental models have confirmed a critical role for type I IFN signaling in mediating innate immune “sensing” of a growing tumor in vivo. Our results confirm that molecular profiling of melanoma metastases may be useful as a predictive biomarker for response to melanoma vaccines. In addition, specific features identified in defined subsets of patients offer new therapeutic strategies based on overcoming resistance to immune destruction at the level of the tumor microenvironment.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr SY19-01. doi:10.1158/1538-7445.AM2011-SY19-01
Abstract SY24-01: Pluripotency genes as targets for cancer prevention
Authors: Dhodapkar Kavita
Published: June 2012

Recent studies have suggested an overlap between the core pathways that maintain pluripotency in embryonal stem (ES) or induced pluripotency stem (iPS) cells and those implicated in oncogenesis. The presence of ES/iPS signature genes can be demonstrated in diverse cancers and correlates with a poorer outcome. The ES pathways have been shown to be particularly expressed in the putative cancer stem cell (CSC) population within the tumor bulk. Therefore pathways that regulate stemness are being actively targeted in human cancer. Here, I will discuss evidence for immune-mediated targeting of the core ES genes, such as OCT4 and SOX2 in humans. Initial studies suggested that humoral and cellular responses against SOX2 can be detected in patients with preneoplastic monoclonal gammopathy of undetermined significance (MGUS). Presence of anti-SOX2 T cell responses correlated with reduced risk of progression to clinical myeloma. Surprisingly, T cell responses against OCT4, a common marker of ES cells, can be readily detected in healthy human donors. OCT4-specific T cell response resides predominantly in the CD4+ T cell compartment and comprises of CD45RO+ memory T cells. These T cells can be readily expanded in culture using autologous dendritic cells loaded with OCT4-expressing germ cell tumors. In contrast to the finding with healthy donors, T cell immunity to OCT4 is deficient in freshly isolated circulating T cells from patients with germ cell tumors (GCTs). However, these T cells can be observed after chemotherapy-induced cell death of tumor cells in vivo. The capacity of the human immune system to target both of the core pluripotency genes (SOX2 and OCT4) may facilitate harnessing the immune system against GCTs and putative CSCs in diverse tumor types. ES-associated genes such as OCT4 seem to be dispensable for the function of adult stem cells in mice, suggesting that targeting these genes in the setting of cancer might not carry adverse effects against normal adult stem cells. As these immune responses seem to be engaged during early stages of carcinogenesis, including in preneoplastic states, we suggest that they may also be particularly attractive targets for immune-mediated cancer prevention in diverse high-risk settings.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr SY24-01. doi:10.1158/1538-7445.AM2011-SY24-01
Abstract SY26-02: Targeting lipogenesis in EGFR-activated glioblastomas
Authors: Mischel Paul S.
Published: June 2012

Cancer is a disease characterized by mutational activation and enhanced dependence on oncogenic signal transduction cascades. Cancer is also characterized by major shifts in cellular metabolism, including glucose utilization and uptake, energy metabolism and lipogenesis. The molecularly circuitry linking oncogenic signal transduction cascades and therapeutically targetable metabolic circuits is only beginning to be understood. This talk will focus on glioblastoma, the most common malignant primary brain tumor of adults and one of the most lethal of all cancers. Glioblastoma is characterized by nearly universal PI3K pathway hyperactivation, including EGFR amplification and mutation. Studies leading to molecular dissection of the signaling networks linking mutated EGFR with enhanced lipogenesis will be discussed, including integration of studies performed in cell lines, in vivo models and tumor tissue from patients treated with targeted inhibitors. The talk will describe the identification of a therapeutically targetable, novel EGFR/PI3K/SREBP-1 dependent prosurvival metabolic signaling pathway, as well as recent studies linking this pathway to altered fatty acid synthesis and cholesterol homeostasis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr SY26-02. doi:10.1158/1538-7445.AM2011-SY26-02
Abstract A24: Germline deletion at 3p12.3 in patients with hereditary breast and colorectal carcinoma
Authors: Abreu Francine B. , Santos Erika MM , Rossi Benedito M. , Krepischi Ana C. , Achatz Maria I. , Carraro Dirce M. , Brentani Ricardo R. , Kowalski Luiz P. , Rogatto Silvia R.
Published: June 2012

Lynch syndrome (LS) is a common hereditary syndrome that predisposes to colorectal cancer (CRC). Breast carcinoma has been described as the most common extracolonic tumors among Brazilian patients with LS. In this study, it was investigated members of two families with breast and colorectal carcinomas. The patient 1 (SM56) had breast carcinoma at age of 50. The patient 2 (SM37) had CRC at 52 years old, presented bilateral breast carcinoma (73 and 76 years old) and reported a reproductive history of four abortions. The daughter of patient 2 (SM37-2) had breast cancer at 55 years old. In both families, their relatives had history of CCR, breast cancer, endometrium carcinoma and prostate cancer. The patients were screened for BRCA1, BRCA2, CHEK2, TP53, MLH1 and MSH2 mutations by Sanger's sequencing method. All of them were negative for pathogenic mutations. Copy number alterations (CNAs) were investigated by array comparative genomic hybridization (aCGH) using a platform of 4×180K (Agilent). Genomic data were extracted with Feature Extraction software and analyzed using Genomic Workbench Standard 5.0.14, statistical algorithm ADM2 and sensitivity threshold of 6.7. The data were compared with the Database of Genomic Variations (DGV) and with a reference dataset obtained from 82 healthy Brazilian individuals. Alterations identified in more than 5% of the reference dataset were excluded from both patients. All three cases presented the same microdeletion on 3p12.3 (79.951 pb) where is mapped the ROBO1 gene. Quantitative Real Time PCR (qPCR) using primers flanking the region confirmed the ROBO1 microdeletion. CNAs mapped on ROBO1 or involving the same region microdeleted are not previously described in DGV or in our dataset from Brazilian health individuals. ROBO1 is involved in the regulation of cell migration, cell death and angiogenesis. The 5′ region contains a CpG island and was found to be hypermethylated and showing allelic losses in 3p12 in sporadic primary invasive breast carcinomas (Dallol et al, Oncogene 21:3020, 2002). At first time, ROBO1 was associated with Hereditary Breast and Colorectal Carcinomas in two different families suggesting to be a highly penetrant mutation associated with elevated risk to develop cancer among the relatives. Further studies in tumor samples from these patients could demonstrate the Knudson's two hit hypothesis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A24.
Abstract A37: A dominantly acting allele of murine Mcm4 causes chromosome instability and promotes leukemiogenesis
Authors: Bagley Bruce N. , Maklakova Vilena , Kendziorski Christina , Adams David J. , Collier Lara S. , Marshall Jonathon G. , Lester Rachael A. , Cancel Michelle M. , Bendzick Laura G. , Keane Thomas , Kogan Scott C. , Sullivan Ruth , Cormier Robert
Published: June 2012

Mouse models have been invaluable tools for studying human cancer. Given the contribution of mouse models to understanding tumorigenesis, when a spontaneous mouse mutant that developed heritable T cell lymphoblastic leukemia/lymphoma (T-ALL) arose in our colony, we pursued studies to both characterize the disease in these mice and to identify the mutant gene responsible for the phenotype. Because the mutation was spontaneous and the phenotype was dominant, we named the mutant Spontaneous dominant leukemia (Sdl). Sdl heterozygous mice develop disease with short latency and high penetrance; while mice homozygous for the mutation die early during embryonic development. We have discovered a spontaneously acquired mutation in Mcm4 in Sdl mice by whole exome sequencing. MCM4 is part of the heterohexameric complex of MCM2–7 that is important for licensing of DNA origins prior to S phase and also serves as the core of the replicative helicase that unwinds DNA at the replication fork. Previous studies in murine models have discovered that reduced levels of MCM complexes resulting from hypomorphic Mcm alleles promote tumor formation by causing genomic instability. However, Sdl mice possess normal levels of MCMs and there is no evidence for loss-of-heterozygosity at the Mcm4 locus in Sdl leukemias; indicating that the Sdl Mcm4 allele is not a hypomorphic or loss-of-function allele. Sdl mice harbor increased numbers of spontaneous micronuclei and Sdl T-ALLs are characterized by intragenic deletions at the Notch1 locus. Therefore, our studies indicate that dominantly acting alleles of MCMs can be compatible with viability but have dramatic oncogenic consequences caused by chromosome instability.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A37.
Abstract A7: Participation of atopic condition in melanoma B16-BL6 development
Authors: Jimenez-Andrade G. Yanek , Lamas Monica , Gonzalez-Espinosa Claudia
Published: June 2012

Atopy is a condition characterized by the increase of total serum immunoglobulin E (IgE) levels and a tendency to develop allergic reactions. Allergy in general and specifically atopic dermatitis seems to be associated with an increased risk of melanoma development, but those findings are not conclusive. Mast cells play a central role in allergic reactions because they can be activated by IgE-antigen-dependent crosslinking of the Fc Rl receptor. Since mast cells have been found in the periphery of solid tumors and their presence correlates with tumor angiogenesis and growth, it has been proposed that activation of mast cells may facilitate blood vessel formation and tumor development.

We evaluated the melanoma growth in atopic states and the role of mast cells in this process. Since hyper-responsiveness is a critical condition in atopic states, we developed a murine model of atopic condition that allowed us to quantify the increase in the inflammatory state in mice. C57BL/6J mice were sensitized with intravenous (i.v) injection of different concentrations of a monoclonal anti-DNP IgE (SPE-7 clone). Twenty-four hours after IgE administration, atopic condition was evaluated by cutaneous passive anaphylaxis (PCA) assays. A specific antigen for the SPE-7 IgE (DNP-HSA) was i.v. injected together with in Evans blue colorant and extravasation of the colorant was quantified by standard methods.

C57BL/6J control and atopic mice were inoculated subcutaneously with 0.5×106B16-BL6 melanoma cells in serum-free Tyrode's buffer 24 hours after vehicle or IgE (750 ng i.v.) administration. Tumor weight was assessed during 4 weeks after inoculation of tumor cells in the ear. Results shown that tumor growth was faster in atopic than non-atopic mice.

To investigate the role of mast cells in melanoma growth in atopic condition, we evaluated the tumor weight gain in mast cell deficient Kit (Wsh/Wsh) (W-sh) and mast cell reconstituted (W-sh-rec) mice in normal and atopic conditions. Melanoma tumor growth was impaired in non-atopic and atopic W-sh mice and restored in non-atopic W-sh rec. Interestingly, melanoma growth was greater in W-sh rec atopic mice than in all the groups tested.

Our results suggest that atopic condition facilitates melanoma tumor growth and that mast cells participate in this effect.

This work was supported by CONACyT Grants 83079 and 79162. Scholarship 210067.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr A7.
Abstract B17: Synergism between p53 and Mcl-1 in hepatocyte maturation and survival
Authors: Weng Shih-Yen , Hsiao Michael , Huang Pei-Hsin , Tao Mi-Hua , Yang-Yen Hsin-Fang , Yang Chia-Yu , Li Chao-Chin , Sun Te-Ping , Tung Shu-Yun , Yen Jeffrey Jong-Young , Tsai Ting-Fen , Chen Chun-Ming , Chen Sung Ho
Published: June 2012

Mcl-1 plays an apical role in many cell survival programs. Mice without Mcl-1 die at early embryonic stage. A conditional knockout approach has thus been employed to study Mcl-1 functions in the liver. Mice without Mcl-1 in hepatocytes (Alb-Mcl-1 −/−) were viable but manifested some defects in the mature liver, including enlarged cell size, enhanced apoptosis and proliferation of liver cells. An increased level of p53 was also observed in adult Alb-Mcl-1 −/− mouse livers. We thus generated Alb-Mcl-1 −/− mice in p53-deficient background to examine whether p53 was involved in Mcl-1 deficiency-induced hepatocyte apoptosis. Loss of p53 in Alb-Mcl-1 −/− mice (DKO mice) resulted in a very high frequency of neonatal death. Further analysis revealed that such early lethality was likely due to hepatic failure caused by a marked reduction of fully-differentiated hepatocytes at the perinatal/neonatal stage. On the other hand, those DKO mice that did survive to adulthood manifested much more severe liver cell damage than Alb-Mcl-1 −/−mice of the same age, suggesting that p53 is activated in Alb-Mcl-1 −/− livers to help resolve Mcl-1 deficiency-induced hepatocyte damage. Last, we demonstrated that p53 enhanced-hepatocyte survival is a cell-autonomous effect, and that such effect is mediated in part through transcriptional up-regulation of p21 Waf1/Cip1 in Alb-Mcl-1 −/− livers.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr B17.
Abstract B19: Cigarette smoke promotes human airway epithelial migration through temporal coordination of p120-catenin-dependent and -independent pathways
Authors: Zhang Lili , Gallup Marianne , Zlock Lorna , Finkbeiner Walter E. , McNamara Nancy A.
Published: June 2012

Background: Cigarette smoking has been linked to almost all major types of cancer. Emerging evidence suggests that smoking initiates transformed cell growth and migration by disrupting cell-cell interactions in the polarized mucosal epithelium. Together with other adherens junction proteins, p120-catenin (p120ctn) maintains cell-cell adhesion through its direct interaction with E-cadherin. Mislocalization and/or loss of p120ctn have been reported in all lung cancer subtypes and are related to poor prognosis. Our purpose was to investigate the initiating (intact p120ctn) and late (loss of 120ctn) events of smoke-promoted lung carcinogenesis using primary human bronchial epithelial (HBE) cells.

Methods: Wide-type and p120ctn-knockdown HBE cells exposed to cigarette smoke-conditioned medium were used to mimic the early and late progressive stages of lung cancer. Signaling cascades and cell migration under the two conditions were investigated.

Results: Src and Jnk activation by smoke were delayed in p120ctn-knockdown cells and inhibition of migration through the chemical blockade of EGFR, Src, and/or Jnk was dependent on p120ctn. In contrast, chemical inhibition of signaling via Akt (cell survival) or Erk (cell proliferation) was sufficient to block smoke-induced migration independent of p120ctn. Also independent of p120ctn was smoke's effect on the RhoGTPase, Rac1. Rac1 knockdown abolished dephosphorylation of actin binding protein, cofilin, in the presence and absence of p120ctn, indicating its essential role in smoke-induced cell migration.

Conclusions: These studies provide unprecedented insight regarding the multiple and interdependent molecular strategies employed by smoke to escape tightly regulated cellular processes such as cell migration, proliferation, and survival.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr B19.
Abstract B45: Embryogenesis meets tumorigenesis: Nodal/activin signaling drives self-renewal and invasiveness of pancreatic cancer stem cells
Authors: Lonardo Enza , Hermann Patrick C. , Mueller Maria-Theresa , Miranda-Lorenzo Irene , Heeschen Christopher
Published: June 2012

Nodal and activin belong to the TGF-β superfamily and are important regulators of embryonic stem cell fate. Here we investigated whether Nodal and/or Activin regulate self-renewal and invasiveness of pancreatic cancer stem cells. While their expression was hardly detectable in differentiated pancreatic cancer cells, cancer stem cells demonstrate a drastic upregulation for Nodal and, to a lesser extent, Activin while TGF-β remained unchanged. Pancreatic stellate cells as the putative microenvironment for cancer stem cells produce very high amounts of Activin, and, to a lesser extent, Nodal. Knockdown and pharmacological inhibition of their common receptor Alk4/7 both significantly, but reversibly reduced cancer stem cell self-renewal / invasiveness and cancer stem cells subsequently became sensitive to gemcitabine. Importantly, while orthotopically engrafted primary human cancer cell suspensions were highly responsive to Nodal/Activin inhibition plus gemcitabine, engrafted primary human pancreatic cancer tissue xenografts containing massive stroma did not slow down tumor progression. Intriguingly, the addition of a stroma-targeting sonic hedgehog pathway inhibitor resulted in enhanced delivery of the Nodal/Activin inhibitor and gemcitabine, respectively, and translated into long-term disease stabilization. Therefore, modulation of the Alk4/7 pathway, if combined with hedgehog pathway inhibition and gemcitabine, provides a novel therapeutic strategy for targeted elimination of cancer stem cells in order to overcome their resistance towards gemcitabine.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr B45.
Abstract B56: Organelle targeted photodynamic therapy
Authors: Dhar Shanta
Published: June 2012

The success of a cancer treatment is directly related to its ability to selectively kill cancer cells. Photodynamic therapy (PDT) with a photosensitizer (PS) that targets mitochondria causes a prompt release of cytochrome c into the cytoplasm and activation of caspases-9 and -3, among other caspases, that are responsible for initiating cell degradation. Photofrin is the FDA approved drug for PDT. Mitochondria have repeatedly been implicated as primary targets of porphyrin mediated PDT. However, a systematic study to direct the PDT drugs towards their cellular target, mitochondria of the cancer cell, is not yet fully explored. Phthalocyanins (Pc) are a class of compounds, which are known to successfully address the drawbacks exhibited by the porphyrin-based compounds. PDT, using the second-generation Pc, causes mitochondrial damage and induces apoptosis. However, the Pc molecules are hydrophobic and must be encapsulated within a liposomal formulation for successful delivery. Given that most effective PDT drug candidates act on the mitochondria of cancer cells and their hydrophobicity require suitable delivery vehicles for their intracellular accumulation, we hypothesize that the construction of engineered targeted drug delivery systems to direct PDT drugs to the mitochondria of the cancer cells would allow an effective phototherapeutic action. This would result in a higher local concentration of singlet oxygen in the mitochondria of cancer cells. In order to study this hypothesis, we have initiated the synthesis of a series of mitochondria targeting polymers to study nanoparticle (NP) assisted targeted delivery and anticancer properties of metallo phthalocyanins. The synthesis and biological activity of these constructs will be discussed.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr B56.
Abstract C23: Epigenetic regulation of miRNAs and influence on malignancy in Ewing tumors
Authors: Richter Guenther H.S. , Plehm Stephanie , Burdach Stefan
Published: June 2012

Although microRNAs (miRNA) were shown to be involved in cancer progression of many tumor entities, little is known about the role of non-coding RNAs in Ewing Tumor (ET) pathogenesis. The highly malignant ET comprise the second most common type of bone associated cancers in children and are characterized by oncogenic ews/ets translocations. We previously observed the histone methyltransferase Enhancer of Zeste, Drosophila, Homolog 2 (EZH2) to be regulated by EWS-FLI1 and highly increased in ET.

Here we demonstrate that EZH2 occupies promotor regions of putative tumor suppressor miRNAs and differentiation associated miRNAs in ET. We show that EZH2 mediates silencincig of miRNA expression via histone modification as well as DNA methylation and that these miRNAs are reactivated upon EZH2 knock down or treatment with inhibitors histone deacetylation and DNA methylation. In addition, we show that the well-known oncogenic miRNA221 is highly expressed in ET and processed in the presence of Argonaute (AGO) protein 2. Using RNA interference we observed that AGO1 and AGO2 mediated processes affect cellular invasiveness and anchorage-independent proliferation in vitro and influence ET growth and metastasis in immunodeficient Rag2−/−γC−/− mice, confirming an involvement of non-coding RNAs in ET pathogenesis.

Taken together, these data illuminate the hitherto unknown epigenetic regulation of miRNA expression by EZH2 in ET and a general involvement of noncoding RNA in ET-pathogenesis, opening the avenue for new therapeutic modalities i.e. the implementation of miRNA therapeutics.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr C23.
Abstract C38: Berberine/cisplatin-based radiotherapy for cervical cancer: The new and effective method to treat cervical cancer
Authors: Komal Komal , Naseem Akhtar , Deshwal Vishal Kumar , Sharma Alpana
Published: June 2012

Background: Cervical cancer is the most common cancer in Indian females. The present treatment regime for cervical cancer is radiotherapy based on DNA crosslinking agent like cisplatin which is associated with various side effects. Berberine, a chemopreventive agent, is a natural compound extracted from Berberidaceae family that allows suppression and retardation of carcinogenesis and effectively inhibits inflammation. The objective of this study was to compare the cisplatin-based radiosensitization with a berberine/cisplatin-induced radiosensitization.

Methods: HeLa, SiHa, and Ca Ski cells were cultured in DMEM medium supplemented in 10% FBS in a humidified atmosphere of 95% air and 5% CO2 at 37°C and were treated with 75 μM berberine/10 μg cisplatin and 10 μg cisplatin alone for 24 hrs followed by 2 Gy radiation dose from radiation source. Cells which were not sensitized with berberine/cisplatin were also treated with variable radiation doses. Apoptosis was measured by flow cytometery, protein expression was assessed using Western blotting, and caspase activity was measured using synthetic substrates.

Results: Treatment of cervical cancer cells with berberine/cisplatin combination dose followed by radiation resulted in increased apoptosis in comparison to cisplatin sensitization and exposure to radiation. The combination of berberine/cisplatin resulted in increased expression of proapoptotic Bax, p73 and downregulation of antiapoptotic Bcl XI, inflammatory Cox 2, cyclin D1 and effective reduction in activity of telomerase in comparison to cisplatin-based radiotherapy. The combination dose also resulted in increased activation of caspase-9 and -3.

Conclusion: The present study indicates that berberine has the potential to make cervical cancer therapies more effective and safer with minimization of side effects which are associated with generation of excessive reactive oxygen species in present cisplatin-based therapy regime.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr C38.
Abstract C56: Characterization of PinX1 as a coregulator of steroid hormone receptors
Authors: Noriega Yamilet , Rivas Miguel , Langley Elizabeth
Published: June 2012

Introduction: Deregulated expression of transcriptional coactivators and corepressors has been implicated in tamoxifen (TAM) resistance, especially in ER+ breast cancer patients. The AF-1 transcriptional activation domain in the N-terminus of ER has been implicated in the tissue specific agonistic effects of TAM. Thus, using the yeast two-hybrid system with the N-terminal region of ERα, we located the PINX1 gene which encodes for a telomerase inhibitor.

Objective: In this work, we characterized PinX1 as a coregulator of ERα.

Methods and Results: Using GST pull-down assays, we confirmed the direct interaction between PinX1 and the N-terminus of ERα, showing no interaction with the C-terminus either in the presence or absence of estradiol (E2). Transcriptional activation assays using luciferase reporter genes show that PinX1 is capable of increasing ERα transcriptional activity in breast cancer cell lines, at low concentrations, but increasing PinX1 exhibits a negative effect on the transcriptional activity of ERα in these cell lines. However, Pinx1 repressed AF-1 transcriptional activity, as well as AF-2 activity in the presence of E2. ChIP assays verified that the interaction between ERα and Pinx1 occurs on E2 regulated promoters after 2h of incubation with E2. Furthermore, PinX1 inhibits E2 induced proliferation of MCF7 cells, while inhibition of PinX1 by siRNA increases E2 induced proliferation. These results suggest a role for PinX1 as a correpresor of ERα. PinX1 also interacts with the androgen and progesterone receptors. However, we demonstrate that PinX1 is a coactivator of these receptors by luciferase assays, as well as increasing DHT induced proliferation of prostate cancer cell lines. Enhanced expression of PinX1 also deregulates the expression of a number of genes that have a role in cell growth and proliferation in breast cancer cell lines.

Conclusions: Our data support a dual role for PinX1 as a correpresor of ERα and a coactivator of AR and PR. Additionally, it may be involved in functions regulating cell growth and proliferation in both breast and prostate cancer cell lines.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr C56.
Abstract IA1: Building molecules to guide anticancer therapy
Authors: Olson Emilia S. , Tsien Roger Y. , Savariar Elamprakash N. , Crisp Jessica L. , Jiang Tao , Aguilera Todd A. , Whitney Mike A. , Steinbach Paul , Ellies Lesley G. , Nguyen Quyen T.
Published: June 2012

For clinical imaging, we need synthetic molecules with novel amplifying mechanisms for homing to diseased tissues. Activatable cell penetrating peptides (ACPPs) are polycationic cell penetrating peptides (CPPs) whose cellular uptake is minimized by a polyanionic inhibitory domain and then restored upon proteolysis of the peptide linker connecting the polyanionic and polycationic domains. Local activity of proteases able to cut the linker causes amplified retention in tissues and uptake into cells. ACPPs on dendrimers labeled with Cy5 and Gd-DOTA enable whole body magnetic resonance imaging (Olson et al (2010) PNAS 107: 4311–4316) followed by fluorescenceguided surgery. Such fluorescence guidance improves tumor-free survival in two animal models (Nguyen et al (2010) PNAS 107: 4317–4322). Contrast for tumor over normal tissues is amplified and accelerated when the polyanionic domain includes an acceptor of fluorescence resonance energy transfer (FRET), because loss of FRET (monitored either by multispectral emission or donor excited-state lifetime) instantly signals proteolysis without waiting for uncleaved substrate to wash out of normal tissues. Thrombin-cleavable ACPPs accumulate in atherosclerotic plaques, and their labeling intensity seems to correlate with progression towards rupture. Separately, we have developed fluorescent peptides that light up peripheral nerves to show surgeons where not to cut (Whitney et al (2011) Nature Biotech. 29: 352–356). Thus we believe that basic tumor biology and molecular design can help improve early detection and surgical resection, not just chemotherapy.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr IA1.
Abstract IA16: Technologies for detecting and analyzing proteins in living cells
Authors: Tina Alice Y.
Published: June 2012

Two technologies will be described: (1) a generic way to label specific recombinant proteins inside living cells with any chemical probe, and (2) a way to map the proteomic composition of subcellular compartments of living, intact cells.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr IA16.
Abstract IA20: DNA methylation and nucleosome repositioning in cancer
Authors: Jones Peter A.
Published: June 2012

Epigenetic processes are reinforced by interactions between covalent chromatin marks such as DNA methylation, histone modifications, and variants. These marks ultimately specify the locations of nucleosomes particularly with respect to transcriptional start sites and in regulatory regions. Understanding how the epigenome functions therefore requires a coordinated approach so that the mechanisms by which the chemical modifications interact with nucleosomal remodeling machines are achieved to ensure epigenetic inheritance and control of gene expression. We have developed a new methodology to simultaneously map nucleosomal positioning and DNA methylation on individual molecules of DNA. We used this nucleosomal mapping technology to ascertain alterations in nucleosomal positioning during the abnormal silencing of genes by promoter hypermethylation. These experiments show that the methylation of CpG islands at the transcriptional start sites of key tumor suppressor genes results in the stable placement of nucleosomes at the transcription start site. Inhibition of DNA methylation by 5-azanucleoside treatment results in an immediate inhibition of DNA methylation and a sequence of downstream events which ultimately result in the eviction of the nucleosomes from the transcription start site and the activation of gene expression. Interestingly this process requires the insertion of the histone variant H2AZ downstream and upstream of the transcriptional start site for full gene activation to occur. Thus inhibition of DNA methylation by these drugs which are used to treat myelodysplastic syndrome results not only in the removal of DNA methylation but in the resetting of chromatin to an active state. Genes activated in this way often undergo resilencing when the drug is removed so that understanding the precise nature of these alterations is essential in the design of the next generation of epigenetic therapies.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr IA20.
Abstract IA25: Using old mouse models to identify new cancer drug targets
Authors: Hemann Michael T.
Published: June 2012

Effective cancer therapy, using surgery, radiotherapy, or chemotherapy results in the absence of macroscopic disease either at the site of the primary tumor or common distal sites of disease dissemination. Despite this initial tumor clearance, many patients will eventually relapse. Thus, small cohorts of tumor cells can survive in cryptic anatomical loci following therapy. These surviving cancer cells represent minimal residual disease (MRD). While cell-intrinsic processes are known to play decisive roles in chemotherapeutic response and drug resistance, relatively little is known about the impact of the tumor microenvironment on the persistence of MRD. Using a preclinical model of B cell lymphoma, we have been able to show that paracrine release of prosurvival cytokines protects subsets of lymphoma cells from cell death induced by genotoxic chemotherapy. Thus, while genotoxic damage can eradicate systemic disease, it can also, paradoxically, elicit prosurvival signaling in select anatomical sites. To further examine the role of the tumor microenvironment on therapeutic response, we have adapted large-scale loss of function genetic screen approaches for use in models of B cell malignancy in vivo. Specifically, we have made use of comprehensive shRNA libraries to target the genome in an unbiased manner. By introducing large shRNA pools into leukemia cells and transplanting modified cells into syngeneic recipients, we could identify up to 9,000 unique hairpins in individual mice, suggesting that library diversity can be maintained in this setting, and that genome-scale shRNA libraries can be screened in vivo. Genes identified using this approach represent central mediators of leukemia cell survival and potential cancer drug targets.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr IA25.
Abstract IA26: Finding mechanisms of cancer drug resistance through functional genetic screens
Authors: Bernards Rene
Published: June 2012

Unresponsiveness to therapy remains a significant problem in the treatment of cancer, also with the new classes of cancer drugs. In my laboratory, we use functional genetic approaches to identify biomarkers that can predict responsiveness to targeted cancer therapeutics; drugs that specifically inhibit molecules or pathways that are often activated in cancer. Nevertheless, it remains poorly explained why a significant number of tumors do not respond to these therapies. We aim to elucidate the molecular pathways that contribute to unresponsiveness to targeted cancer therapeutics using a functional genetic approach. This will yield biomarkers that may be useful to predict how individual patients will respond to these drugs. Furthermore, this work may allow the development of drugs that act in synergy with the established drug to prevent or overcome drug resistance.

To identify biomarkers that control tumor cell responsiveness to cancer therapeutics, we use multiple complementary approaches. First, we use genome wide loss-of-function genetic screens (with shRNA interference libraries) in cancer cells that are sensitive to the drug-of-interest to search for genes whose down-regulation confers resistance to the drug-of-interest (resistance screens). In addition, we use single well siRNA screens with a low dose of the drug to screen for genes whose inhibition enhances the toxicity of the cancer drug (sensitizer screens). As a third approach, we use gain of function genetic screens in which we search for genes whose over-expression modulates drug responsiveness. Once we have identified candidate drug response biomarkers in relevant cell line models, we ask if the expression of these genes is correlated with clinical response to the drug-of-interest. For this, we use tumor samples of cancer patients treated with the drug in question and whose response to therapy is documented.

In a fourth and distinct approach we perform high throughput sequencing of the “kinome” (some 600 genes) or whole exome of tumor samples to identify connections between cancer genotype and drug responses.

Examples of these four approaches to identify mechanisms of resistance to different cancer drugs will be presented.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr IA26.
Abstract PR2: A genetic screen for novel determinants of anoikis resistance identifies PVRL4
Authors: Pavlova Natalva N. , Elledge Stephen J.
Published: June 2012

Tumor cells develop resistance to detachment-induced cell death, known as anoikis, and rely on it for survival throughout the course of disease progression. Through a gain-of-function genetic screen for novel determinants of anoikis resistance, we found that PVRL4 (poliovirus receptor-like 4) promotes anchorage-independent colony formation in HMECs (human mammary epithelial cells).

PVRL4 belongs to a family of transmembrane proteins involved in early stages of adherens junction formation. PVRL4 is expressed in focally amplified in breast cancer and positively correlates with spread of cancer into lymph nodes and poor survival prognosis. PVRL4 promoted cell aggregation of HMECs, and induction of cell aggregation was sufficient to promote anchorage-independent colony formation. Cell aggregation and transformation induced by PVRL4 were abrogated in presence of a monoclonal antibody targeting its extracellular region. Furthermore, stable depletion of PVRL4 in breast cancer cells inhibited spontaneous cell aggregation and anchorage-independent growth. Taken together, our findings demonstrate the key role of PVRL4 in cellular transformation and suggest that it functions via promoting cell aggregation.

Cancer cells are known to exhibit increased cell aggregation; moreover, increased cell aggregation correlates with metastatic potential. Multicellular clusters of cancer cells are present among circulating tumor cells (CTCs) blood from cancer patients and as well as in mouse cancer models. Promotion of survival in the absence of attachment via inducing cell aggregation may therefore provide a unique advantage for CTC survival in the bloodstream and spread into distant organs. Finally, inhibition of PVRL4-induced aggregation and anchorage-independence by monoclonal antibodies demonstrates a potential new therapeutic strategy against breast cancer.

This abstract is also presented as Poster B5.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr PR2.
Abstract A105: Blood donation in relation to colorectal cancer risk in men
Authors: Zhang Xuehong , Ma Jing , Wu Kana , Chan Andrew T. , Fuchs Charles S. , Giovannucci Edward L.
Published: June 2012

Background: Excessive iron may increase colorectal cancer risk, as shown in vitro and animal studies. Human observational studies of iron intakes and body iron stores in relation to colorectal cancer risk have been conflicting, which may partly due to non-specific measurement of iron status. We used the lifetime number of blood donation, a validated determinant of serum ferritin, to investigate the iron hypothesis, which has only been examined in one prior study. Serum ferritin is a reliable measure of body iron stores. Thus, the hypothesis of the depletion of body iron stores lowering the colorectal cancer risk can be tested by comparing colorectal cancer risk between regular blood donors and non-donors.

Method: We prospectively examined the association between lifetime number of blood donations and colorectal cancer risk in the Health Professionals Follow-up Study. Information on number of blood donation and other colorectal cancer risk factors was obtained in 1992 questionnaire. A Cox proportional hazard regression was used to estimate the multivariable relative risks (RRs, 95%CIs).

Results: We documented 659 incident colorectal cancer cases during 16 years of follow-up. The age-adjusted results yielded essentially the same results as the multivariable results. Comparing with the non-donors, the multivariable RRs (95%CIs) were 0.95 (0.79, 1.15) for 1–4 donation, 0.86 (0.65, 1.13) for 5–9 donations, 0.97 (0.73, 1.29) for 10–19 donations, 0.89 (0.60, 1.31) for 20–29 donations, and 1.16 (95%CI: 0.82, 1.63) for at least 30 donations (P-value for test for trend = 0.46). In addition, the null associations did not vary by colorectal cancer sub-sites, or levels of intakes of total iron and heme iron.

Conclusion: Lifetime number of blood donation is not associated with risk of developing colorectal cancer risk in men. Our results do not support an important role of body iron stores in colorectal carcinogenesis.

Citation Information: Cancer Prev Res 2011;4(10 Suppl):A105.