bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract B27: CDK inhibition impairs homologous recombination and induces PARP inhibitor sensitivity via loss of c-myc expression in TNBC
Authors: Carey Jason Patrick , Keyomarsi Khandan
Published: October 2015

The c-myc oncogene is a “master regulator” amplified in several types of cancer including ovarian, breast, colorectal and pancreatic cancers. C-myc controls several cellular processes during tumor maintenance including the cell cycle, metabolism, and DNA damage repair while also playing an essential role in transforming normal cells during tumorigensis. C-myc amplification correlates with poor survival and a higher frequency of relapse in triple negative breast cancer (TNBC) patients. C-myc amplification promotes deregulation of the cell cycle, via transcriptional activation of G1-S-phase cell cycle and DNA replication genes. CDK inhibition has been shown to down regulate c-myc expression in cancer cells, in vitro. Therefore, we hypothesize that transient CDK inhibition downregulates c-myc expression and increases susceptibility to DNA damaging agents in TNBC cells. We observed the long-term response of several c-myc overexpressing TNBC cells to Dinaciclib, a potent CDK inhibitor (CDK 1, 2, 5, 9) in vitro. High Throughput Survival Assay (HTSA) analysis revealed that c-myc expressing TNBC cells have a potent response to CDK inhibition via Dinaciclib (IC50 10-20nM). Dinaciclib induces an S-phase arrest and downregulation of the c-myc/E2F1 pathway in both normal (MCF10A) and TNBC (MB231, SUM149, HCC1937) breast cancer cells. Loss of c-myc expression correlates with increased apoptosis in TNBC cells but not HMECs. C-myc downregulation also correlates with increased γH2AX DNA damage and downregulation of BRCA1 foci formation. The resultant impaired homologous recombination (HR) pathway in TNBC cells treated with Dinaciclib proposed an increased susceptibility to PARP inhibitor induced DNA damage. Combination Dinaciclib + PARP inhibition exhibited a Dinaciclib dose dependent synergistic growth inhibition of BRCA1 wild-type and mutant TNBC cells to PARP inhibitors. Dinaciclib also increased susceptibility of PARP inhibition in resistant BRCA1 mutant cell lines (HCC1937, SUM149). Dinaciclib + PARP Inhibitor combination therapy induced increased apoptosis, γH2AX DNA damage and decreased BRCA1, RAD51 foci formation. These results demonstrate that Dinaciclib + PARP inhibition induces growth arrest and induction of apoptosis in c-myc overexpressing cancer cells. C-myc is frequently amplified in TNBC tumors and may serve as a biomarker for CDK + PARP inhibitor combination therapy.

Citation Format: Jason Patrick Carey, Khandan Keyomarsi. CDK inhibition impairs homologous recombination and induces PARP inhibitor sensitivity via loss of c-myc expression in TNBC. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr B27.
Abstract B32: Pro-apoptotic functions of AMPK revealed by Myc
Authors: Haikala Heidi M. , Marques Elsa , Eskelinen Vilja , Viheriäranta-Nieminen Anni , Saarikoski Sirkku , Nevalaita Liina , Kovanen Panu , Heikkilä Päivi , Leidenius Marjut , Laajala Daniel , Aittokallio Tero , Munne Pauliina , Klefström Juha
Published: October 2015

Oncogenic transcription factor Myc deregulates the cell cycle and simultaneously reprograms cellular metabolism to meet the biosynthetic and bioenergetic needs of proliferation. Myc also sensitizes cells to mitochondria-dependent apoptosis. Although metabolic reprogramming has been circumstantially connected to vulnerability to apoptosis, the connecting molecular pathways have remained poorly defined. Our recent studies revealed that Myc-dependent ATP depletion activates the energy sensor AMP-activated protein kinase (AMPK), which induces stabilizing phosphorylation of p53 at Ser15. AMPK-stabilized tumor suppressor protein p53 then accumulates in the mitochondria and interacts with the protein complex comprised of Bak and Bcl-xL, to sensitize cells to apoptosis. These results reveal an unexpected pro-apoptotic function of AMPK in context of Myc transformed cells.

We have explored possibilities to therapeutically exploit the Myc-AMPK facilitated apoptosis pathway. We show that a BH3-mimetic small molecule ABT-737, which neutralizes Bcl-2 and Bcl-xL, sensitizes to Myc-dependent apoptosis ex vivo and in vivo WAP-Myc tumours. ABT-737 also reduced WAP-Myc driven primary tumor growth and lung metastases in transgenic and syngrafted mice. Nevertheless, ABT-737 only delayed but did not prevent the formation of Wap-Myc tumors.

In a drug combination screen designed to identify small molecules that potentiate the efficacy of ABT-737, we found several compounds influencing the status of AMPK activity. The synergistic apoptotic action between ABT-737 and AMPK modulating agents has been validated in explant 3D cultures from patient derived Myc positive breast cancers. The mechanisms behind the proapoptotic AMPK function will be discussed. Our results provide evidence that AMPK has a context-dependent pro-apoptotic function that can be therapeutically exploited as a tumour cell-specific vulnerability.

Citation Format: Heidi M. Haikala, Elsa Marques, Vilja Eskelinen, Anni Viheriäranta-Nieminen, Sirkku Saarikoski, Liina Nevalaita, Panu Kovanen, Päivi Heikkilä, Marjut Leidenius, Daniel Laajala, Tero Aittokallio, Pauliina Munne, Juha Klefström. Pro-apoptotic functions of AMPK revealed by Myc. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr B32.
Abstract B43: Reversible linkage of two distinct small molecule inhibitors of MYC generates a more potent and selective dimeric inhibitor that is active in cancer cell lines over-expressing MYC
Authors: Wanner Jutta , Romashko Darlene , Werner Douglas S. , May Earl W. , Peng Yue , Schulz Ryan , Foreman Kenneth W. , Russo Suzanne , Arnold Lee D. , Pingle Maneesh , Bergstrom Donald E. , Barany Francis , Thomson Stuart
Published: October 2015

Up to 70% of all human cancers have deregulated or elevated levels of MYC, making MYC a high profile cancer drug target. The disordered structure of the MYC protein has made identifying small molecule inhibitors of this target very challenging, however recent reports have identified molecules that bind to MYC and block its function. Here we describe the successful application of a novel approach for generating selective dimeric MYC inhibitors by modifying and reversibly linking two previously described small molecule inhibitors of MYC (10058-F4 and 10074-G5) that bind to distinct sites in the bHLHZip domain of the protein. We synthesized two directed libraries of monomers based on each of these molecules to identify the optimal dimer configuration required to inhibit MYC activity. Each monomer contains one of the respective ligands, a connector of varying length, and a bioorthogonal linker element that allows reversible dimerization. We identified specific combinations of monomers (termed active dimers), which displayed synergistic inhibition of MYC in biochemical and cellular assays. Through SPR, ELISA and EMSA we demonstrate that these dimers directly bind to MYC, block its interaction with Max and thus its binding to DNA, respectively. These dimeric inhibitors have superior anti-proliferative activity in MYC over-expressing cell lines compared to their monomeric components, and this activity is correlated with a decrease in MYC protein levels and an inhibition of MYC-dependent gene expression. Control combinations that lack a linker element, and thus are unable to form a dimer, do not show any synergistic effects in these assay systems. Collectively, these data validate our new approach to generate selective inhibitors of MYC assembled from smaller, lower affinity components. This approach provides an opportunity for developing novel therapeutics against MYC and other challenging intracellular drug target classes.

Citation Format: Jutta Wanner, Darlene Romashko, Douglas S. Werner, Earl W. May, Yue Peng, Ryan Schulz, Kenneth W. Foreman, Suzanne Russo, Lee D. Arnold, Maneesh Pingle, Donald E. Bergstrom, Francis Barany, Stuart Thomson. Reversible linkage of two distinct small molecule inhibitors of MYC generates a more potent and selective dimeric inhibitor that is active in cancer cell lines over-expressing MYC. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr B43.
Abstract B44: Effects of BET bromodomain inhibitors on replication and cell cycle progression
Authors: Muralidharan Somsundar Veppil , Bhadury Joydeep , Green Lydia , Nilsson Lisa M. , McLure Kevin G. , Nilsson Jonas A.
Published: October 2015

Myc family of transcription factors are deregulated in most cancers and their expression projects a poor prognosis. Genetic and pharmacological inhibition of Myc and several Myc targets leads to tumor regression and apoptosis. Recently, inhibitors of BET Bromodomain proteins (BETi) were shown to have anti-tumor properties and this has been attributed to Myc down-regulation. Here we show that two structurally distinct BETi affects replication and cell cycle progression at low concentrations where the transcriptome remains largely unaltered. Thymidine incorporation and flow cytometry analyses demonstrates that S-phase progression is hindered at these concentrations. However, in a cell-free system replication is not impaired suggesting that BETi-mediated block of replication is linked to effects on chromatin. Furthermore, at higher concentration of BETi, S-phase entry of cells is completely abrogated. Ectopic expression of Myc fails to rescue these phenotypes, suggesting a novel function of BET bromodomain proteins in replication and cell cycle regulation. Our pharmacogenetic screen in the presence of sub-lethal doses of BETi has identified several small molecule inhibitors to synergize with BETi to enhance apoptosis of Myc driven tumors.

Citation Format: Somsundar Veppil Muralidharan, Joydeep Bhadury, Lydia Green, Lisa M. Nilsson, Kevin G. McLure, Jonas A. Nilsson. Effects of BET bromodomain inhibitors on replication and cell cycle progression. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr B44.
Abstract IA01: Myc functions within a transcriptional regulatory network
Authors: Eisenman Robert
Published: October 2015

In this talk I will explore the idea that Myc proteins do not act independently, but rather function in the context of a larger network of transcription factors. This network can be considered as having two interconnected branches, each requiring heterodimerization with either Max or the Max-like protein, Mlx. Max forms heterodimers with Myc and Mxd family proteins (including Mnt and Mga), while Mlx heterodimerizes with the large BHLHZ proteins MondoA and ChREBP. A subset of Mxd proteins also heterodimerize with Mlx. Based on our current knowledge of the organization and the functions of its different components, it is possible to view the network as a transcriptional module that responds to and integrates extracellular and intracellular stimuli in order to modulate gene expression programs that ultimately act to affect cellular behavior. We can consider the three sub-families within the network, Myc, Mxd, and MondoA/ChREBP, as being responsive to mitogenic signaling, growth arrest/differentiation signals, and nutrient availability, respectively. The transcriptional response mediated by these factors is further modified by their ability to interact with other transcriptional regulators (e.g. Miz1) and to recruit chromatin modifying factors.

Importantly, the notion of an extended Max/Mlx network is likely to go beyond the simple wiring diagram described above. For example functional interactions have been described among network members such as the antagonism at molecular and biological levels between Myc and Mxd proteins. Recently we have shown that the metabolic reprograming induced by deregulated Myc proteins in several distinct tumor types is cooperatively regulated by, and dependent on, MondoA-Mlx. The transcriptional changes mediated by Myc-Max and MondoA-Mlx are critical for tumor cell survival. Analysis of Myc's activities within the context of the extended network, as well as the dynamics of the network as a whole, may provide insights into the molecular basis and the consequences of Myc deregulation in the etiology of cancer and new approaches to inhibit Myc.

Citation Format: Robert Eisenman. Myc functions within a transcriptional regulatory network. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr IA01.
Abstract IA03: Role of MYC in germinal-center development and in lymphomagenesis
Authors: Dalla-Favera Riccardo
Published: October 2015

Germinal centers (GCs) are transient structures that form in second¬ary lymphoid organs where B cells are selected on the basis of their ability to produce high-affinity antibodies. B cells in the GCs are also the cells of origin for most B cell lymphomas, including Burkitt Lymphoma carrying chromosomal translocations involving c-Myc. After antigenic challenge, B cells enter the dark zone (DZ) of germinal centers (GCs) to proliferate and hypermutate their immunoglobulin genes. Mutants with greater affinity for the antigen are positively selected in the light zone (LZ) to either differentiate into plasma and memory cells or reenter the DZ. We have shown that the GC reaction requires a biphasic regulation of expression of c-Myc that involves: 1) its transient induction during early GC commitment; 2) its repression by Bcl-6 in highly proliferating DZ B cells; 3) its re-induction in B cells selected for reentry into the DZ. Elimination of c-MYC expression during GC formation results in GC absence, while its inhibition in formed GCs leads to GC collapse. Thus c-Myc has essential roles in early induction of GCs and in their maintenance, by eliminating the LZ-to DZ recirculation. These results suggest an unusual, independent of cell proliferation role of c-Myc in GC development and has implications for the role of c-Myc in lymphomagenesis. By overriding the physiological control of c-Myc expression at critical checkpoints in the GC reaction (entry into the GC and reentry into the DZ), translocations involving immunoglobu¬lin loci and c-MYC may allow B cells to bypass affinity-based selection signals and impose a continuous reentry phenotype that, by perturb¬ing normal GC dynamics, may contribute to lymphomagenesis.

Note: This abstract was not presented at the conference.

Citation Format: Riccardo Dalla-Favera. Role of MYC in germinal-center development and in lymphomagenesis. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr IA03.
Abstract IA04: Neuroblastoma as a paradigm of MYC(N) driven cancers
Authors: Maris John M.
Published: October 2015

Neuroblastoma is an enigmatic childhood cancer with phenotypes ranging from spontaneous regression of seemingly advanced disease to relentless metastatic progression. MYCN amplification was defined as a powerful predictor of metastatic potential and acquisition of therapy resistance in the 1980's, and arguably was the first genomic biomarker utilized in routine clinical practice to stratify therapeutic intensity. While there have been incremental improvements in cure rates over the last three decades, these have come at the cost of a highly complex and intensive chemoradiotherapeutic regimen that leaves survivors with significant long-term morbidity. Here we will discuss our ongoing efforts to define the genetic basis of neuroblastoma, and recent insight into how heritable DNA variation influences neuroblastoma susceptibility and clinical phenotypes, including MYCN amplification. We will also discuss the major oncogenic drivers of high-risk neuroblastoma beyond MYCN, including recent insights into the role of MYC in the MYCN-non-amplified high-risk cases, as well as the major role of the ALK oncogene, often in cooperation with MYCN. Finally, we will discuss recent efforts to leverage this information therapeutically, with a focus on how therapeutically targetable oncogenic pathways evolve under the selective pressure of chemoradiotherapy. Finally, we will discuss nascent efforts to deliver on the holy grail of neuroblastoma translational research—targeting the MYCN oncoprotein itself, discussing opportunities and challenges.

Citation Format: John M. Maris. Neuroblastoma as a paradigm of MYC(N) driven cancers. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr IA04.
Abstract IA05: Targeting MYC-mediated cancer metabolism
Authors: Dang Chi Van
Published: October 2015

Myc, as a transcription factor capable of amplifying gene expression, frequently activates genes involved in cell metabolism to support cell growth and proliferation. Because many metabolic genes are ambiently expressed, it is not surprising in retrospect, that many metabolic genes are targets for Myc-mediated gene expression amplification. Collectively, Myc drives the expression of genes that are involved in glucose uptake, glycolysis, amino acid uptake - particularly glutamine- and catabolism, supporting increased protein synthesis required for a growing cell. In this regard, Myc stimulates many genes involved in nucleotide synthesis, ribosome biogenesis and translation. Furthermore, Myc can stimulate mitochondrial biogenesis and lipogenesis. When Myc is ectopically expressed in oncogenic settings where checkpoints are lost, MYC-transformed cells are constitutively driven to undergo ribosome biogenesis and growth, rendering them addicted to nutrients such as glucose or glutamine. Hence, targeting enzymes that are involved in glycolysis and/or glutaminolysis provides a strategy to treat MYC-driven cancers. We provide proof-of-concept that targeting glutaminolysis in GEMM or xenograft models is feasible and therefore provide a foundation for further studies.

Citation Format: Chi Van Dang. Targeting MYC-mediated cancer metabolism. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr IA05.
Abstract IA07: Metabolic reprogramming by MYC: Lessons learned from adenovirus
Authors: Christofk Heather
Published: October 2015

Viruses are powerful tools to study cancer metabolism. They trigger major metabolic changes in host cells to meet the bioenergetic and biosynthetic demands of virus infection - changes similar to the enhanced glycolysis and anabolic metabolism widely observed in cancer cells. However, unlike cancer cells, viruses undergo intense selection for efficiency, and rapidly and robustly reprogram host cell metabolism through activation of specific key flux-altering nodes, rather than whole metabolic pathway gene sets. We recently reported that adenovirus infection increases host cell anabolic glucose metabolism via MYC activation of specific metabolic target genes, only a subset of those turned on by MYC in many cancers. We are now investigating how adenovirus-induced MYC activation leads to selective transcription of target genes. Additionally, we have generated a list of the specific metabolic genes altered by adenovirus infection and are examining their role in anabolic metabolism, virus replication, and cancer proliferation. Because viruses are so efficient at reprogramming host cell metabolism towards increased anabolism, they represent a powerful tool to identify the most important MYC-induced metabolic enzymes for anabolic metabolism, and potentially the most promising cancer metabolism drug targets.

Citation Format: Heather Christofk. Metabolic reprogramming by MYC: Lessons learned from adenovirus. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr IA07.
Abstract IA10: Post-translational regulation of MYC's oncogenic activity
Authors: Sears Rosalie , Farrell Amy , Wang Xiaoyan , Liang Juan , Janghorban Mahnaz , Su Yulong , Allen-Petersen Brittany , Ohlemeyer Michael , Goutham Narla
Published: October 2015

In response to growth stimulatory signals in normal cells or in transformed cells with constitutive signaling, the c-Myc oncoprotein is post-translationally stabilized through enhanced phosphorylation at the conserved Serine 62 residue. In addition to increasing c-Myc stability, phosphorylation at Serine 62 (pS62-Myc), in conjunction with Proline 63 isomerization mediated by the Pin1 Proline Isomerase, also increases the rate of recruitment of newly synthesized c-Myc to its target genes involved in pro-proliferative phenotypes, enhancing their expression. In normal cells, phosphorylation of S62 primes phosphorylation at a second conserved residue, Threonine 58 (pT58), which then enhance c-Myc degradation by facilitating a second Pin1-mediated isomerization event, which promotes Protein Phosphatase 2A (PP2A-B56α)-mediated dephosphorylation of Serine 62 and recruits the E3 ubiquitin ligase, SCFFbw7. In cancer cell lines as well as patient tumor samples pS62-Myc is elevated relative to non-transformed cell lines or adjacent normal tissue. In order to study the role of pS62-Myc in vivo, we created c-Myc knock-in mice that express either Myc wild-type (WT) or the MycT58A or MycS62A phosphorylation mutant from the ROSA26 locus in response to Cre-recombinase. Analysis of these mice revealed increased tumorigenic potential of MycT58A, which has constitutive S62 phosphorylation as it is resistant to PP2A-mediated S62 dephosphorylation. Together, this research has revealed an important role for S62 phosphorylation and Pin1-mediated isomerization in the tumorigenic activity of c-Myc, which presents new strategies to target c-Myc by inhibiting these post-translational activation steps. Thus, we are currently testing the therapeutic efficacy of PP2A activation and Pin1 inhibition in mouse models of c-Myc-driven tumorigenesis. To create physiologically relevant c-Myc-driven tumor models that engage post-translational activation of c-Myc, we have crossed our ROSA-LSL-MycWT mice with mice carrying organ-relevant oncogenic signaling transgenes. Thus far, we have generated mouse models of Her2+ and Triple Negative breast cancer, and pancreatic cancer. We have demonstrated dramatic tumor growth inhibition with a novel, orally available small molecule PP2A activator drug in these mouse models.

Citation Format: Rosalie Sears, Amy Farrell, Xiaoyan Wang, Juan Liang, Mahnaz Janghorban, Yulong Su, Brittany Allen-Petersen, Michael Ohlemeyer, Narla Goutham. Post-translational regulation of MYC's oncogenic activity. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr IA10.
Abstract IA24: MYC in germinal center B cell physiology and pathology
Authors: Calado Dinis Pedro
Published: October 2015

Germinal centers (GC)s are sites of intense B-cell proliferation, central for T-cell dependent antibody responses. Although much is known of GC B-cell physiology, the mechanisms of cellular proliferation have remained elusive. Specifically, the role of MYC, a key cell cycle regulator, in GC B-cell proliferation has been questioned. We have identified MYC positive B-cell subpopulations in both immature and mature GCs, and shown through genetic ablation of Myc at these stages that they play indispensable roles in GC formation and maintenance, respectively. The identification of functionally critical MYC-expressing GC B-cell subsets has important implications for B-cell lymphomagenesis, which mostly originates from GC cells and frequently involves MYC deregulation through chromosomal translocations. As these translocations are generally dependent on transcription of the recombining partner loci, the MYC positive GC subpopulations may represent B-cells with a particularly high risk for malignant transformation.

Citation Format: Dinis Pedro Calado. MYC in germinal center B cell physiology and pathology. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr IA24.
Abstract PR01: Long noncoding RNA PVT1 potentiates MYC in human cancers with 8q24 gain
Authors: Tseng Yuen-Yi , Bagchi Anindya
Published: October 2015

Copy number gain of the 8q24.21 chromosomal region have been a prominent mutation in many human cancers and are associated with poor prognosis. The well-characterized MYC oncogene, which resides in the 8q24.21 region, has been, conventionally, the attractive candidate driving these cancers. However, MYC is often co-gained with an adjacent ”gene desert” region. This “gene desert” often encompasses the long non-coding RNA gene PVT1, the CCDC26 gene candidate, and the GSDMC gene. Whether low copy number gain of one or more of these genes drives neoplasia is not known. We used chromosome engineering in mice to develop strains containing an extra copy of 1) Myc, 2) Pvt1, Ccdc26, Gsdmc, and 3) Myc, Pvt1, Ccdc26, Gsdmc. When rat Neu was introduced into these three strains to test for changes in latency and penetrance in mammary tumor development, only the mice with an extra copy of Myc, Pvt1, Ccdc26, Gsdmc, (but not those with an extra copy of Myc or Pvt1,Ccdc26,Gsdmc), developed adenocarcinomas with reduced latency, suggesting that while an additional copy of the Myc gene failed to measurably advance cancer, it may co-operate with Pvt1, Ccdc26 or Gsdmc to promote cancer. Si-RNA mediated knockdown of Pvt1/PVT1 reduced the proliferation rates in the mouse mammary tumors, as well as in two human breast cell lines with 8q24 amplification (SK-BR-3 and MDA-MB-231). Silencing of PVT1 markedly decreased MYC protein levels, while no effect was seen in MYC transcript levels, suggesting a PVT1-dependence of MYC protein even in high MYC- amplification cancer cells. Analysis of the TCGA and Progenetix databases suggested that 18% of 45,922 human tumors queried harbor MYC copy number increases, and in >99% of MYC-copy-increase cancers, copy number of PVT1 was co-increased .Tissue microarray analysis using in situ hybridization for PVT1 and immunohistochemistry for MYC revealed that PVT1 RNA and MYC protein expression correlated in primary human tumors. These data together suggested that PVT1 can potentiate MYC in human cancer. CRISPR mediated deletion of PVT1 in colorectal cancer cell line HCT116 either partially or fully ablated tumor formation in xenografts and significantly reduced MYC protein levels by ~50%. We propose that the dependence of high MYC protein levels on PVT1 lncRNA provides a much-needed therapeutic target against MYC protein, which has been refractory to small molecule inhibition.

Citation Format: Yuen-Yi Tseng, Anindya Bagchi. Long noncoding RNA PVT1 potentiates MYC in human cancers with 8q24 gain. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr PR01.
Abstract PR05: Targeting of CDK7 inhibits super-enhancer-associated oncogenic programs in MYCN-amplified tumor cells
Authors: Chipumuro Edmond , Marco Eugenio , Christensen Camilla L. , Kwiatkowski Nicholas , Zhang Tinghu , Hatheway Clark M. , Abraham Brian J. , Sharma Bandana , Yeung Caleb , Altabef Abigail , Perez-Atayde Antonio , Wong Kwok-Kin , Yuan Guo-Cheng , Gray Nathanael S. , Young Richard A. , George Rani E.
Published: October 2015

The MYC oncoproteins are thought to stimulate tumor cell growth and proliferation through amplification of gene transcription, a mechanism that has thwarted most efforts to inhibit MYC function as potential cancer therapy. Using a novel covalent inhibitor of cyclin-dependent kinase 7 (CDK7) to disrupt the transcription of amplified MYCN in neuroblastoma cells, we demonstrate downregulation of the oncoprotein with consequent massive suppression of MYCN-driven global transcriptional amplification. This response translated to significant tumor regression in a mouse model of high-risk neuroblastoma, without the introduction of systemic toxicity. The striking treatment selectivity of MYCN-overexpressing cells correlated with preferential downregulation of super-enhancer-associated genes, including MYCN and other known oncogenic drivers in neuroblastoma. These results indicate that CDK7 inhibition, by selectively targeting the mechanisms that promote global transcriptional amplification in tumor cells, would be useful therapy for cancers that are driven by MYC or its family members.

Citation Format: Edmond Chipumuro, Eugenio Marco, Camilla L. Christensen, Nicholas Kwiatkowski, Tinghu Zhang, Clark M. Hatheway, Brian J. Abraham, Bandana Sharma, Caleb Yeung, Abigail Altabef, Antonio Perez-Atayde, Kwok-Kin Wong, Guo-Cheng Yuan, Nathanael S. Gray, Richard A. Young, Rani E. George. Targeting of CDK7 inhibits super-enhancer-associated oncogenic programs in MYCN-amplified tumor cells. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr PR05.
Abstract PR10: Preclinical validation of Myc inhibition by a new generation of Omomyc-based cell penetrating peptides
Authors: Beaulieu Marie-eve , Whitfield Jonathan , Massó-Vallés Daniel , Jauset Toni , Serrano Erika , Montagne Martin , Maltais Loika , Tremblay Cynthia , Lavigne Pierre , Soucek Laura
Published: October 2015

Deregulated Myc is associated with most human cancers suggesting that its inhibition would be a useful therapeutic strategy. Indeed, we have shown that Myc inhibition displays extraordinary therapeutic benefit in various transgenic mouse models of cancer (i.e skin, lung, pancreatic cancer and glioma) and causes only mild, well-tolerated and reversible side effects in normal tissues. For these studies we employed a dominant negative inhibitor of Myc, called Omomyc, which proved to be the most effective inhibitor of Myc transactivation function both in vitro and in vivo. Omomyc has so far been utilized exclusively as a transgene and served as a proof of principle. Here we report the exciting finding that Omomyc-based Cell Penetrating Peptides (CPPs) are a novel, state-of-the-art method for directly utilizing Omomyc itself (and similar peptides) to treat tumors in the lung and brain, where the peptides biodistribute after intranasal administration. We provide a comprehensive preclinical validation of this innovative therapeutic approach for pharmacological inhibition of Myc in cancer cell lines of different origin and genetic make-up, as well as in a mouse model of Non-Small-Cell Lung Cancer (NSCLC), where the Omomyc-CPPs, like their transgenic counterpart before, display a dramatic therapeutic impact.

Citation Format: Marie-eve Beaulieu, Jonathan Whitfield, Daniel Massó-Vallés, Toni Jauset, Erika Serrano, Martin Montagne, Loika Maltais, Cynthia Tremblay, Pierre Lavigne, Laura Soucek. Preclinical validation of Myc inhibition by a new generation of Omomyc-based cell penetrating peptides. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr PR10.
Abstract PR15: ERK2 binds to MYC promoter and induces MYC expression
Authors: Quintanilla Andrea , Rodriguez Javier , Garcia-Gutierrez Lucía , Lorena Agudo , Crespo Piero , León. Javier
Published: October 2015

It has been known since 30 years ago that serum and growth factors induce a dramatic upregulation of MYC expression in quiescent cells, but the molecular mechanism for this effect is unknown. It has been reported that ERK can bind to DNA and modify gene expression (Hu et al., Cell, 2009). We have investigated the possibility that ERK directly upregulates MYC at the transcriptional level. We have found that: (i) Bioinformatic analyses reveal the presence of ERK binding sites (ERK boxes) conserved in human, mice and rat MYC promoters, located at -0.3 kbp, -1 kbp and -1.7 kbp from the transcription star site; (ii) ERK binds to these ERK boxes by chromatin immunoprecipitation (ChIP) in rat, mouse and human cells upon ERK stimulation, attained either by serum, induction of a N-Ras oncogene or by transfection of a nuclear tethered ERK2; (iii) ERK2 binding correlates with the upregulation of MYC mRNA and protein; (iv) ERK2 activates a luciferase reporter containing a conserved ERK box of the human MYC gene, but not a reporter with the mutated ERK box; (v) ERK2 binds to Cdk9 (the kinase component of pTEFb) in the nucleus as assessed by co-immunoprecipitation and in situ Proximity Ligase Assay (PLA); (vi) the ChIP signal on human MYC promoter detected with anti-ERK2 coincides with that observed with anti-Cdk9 antibodies; and (vii) siRNA-mediated knock-down of Cdk9 impairs MYC up-regulation by ERK2. In the data obtainied so far, we hypothesize that the induction of MYC in response to serum or growth factors might follow this mechanism: growth factors > Ras activation > ERK translocation to nuclei > binding to MYC promoter > recruitment or hyperactivation of pTEFb factor > MYC transcription.

Citation Format: Andrea Quintanilla, Javier Rodriguez, Lucía Garcia-Gutierrez, Agudo Lorena, Piero Crespo, Javier León. ERK2 binds to MYC promoter and induces MYC expression. [abstract]. In: Proceedings of the AACR Special Conference on Myc: From Biology to Therapy; Jan 7-10, 2015; La Jolla, CA. Philadelphia (PA): AACR; Mol Cancer Res 2015;13(10 Suppl):Abstract nr PR15.
Contrast-Enhanced Ultrasound for the Characterization of Hepatocellular Carcinoma and Intrahepatic Cholangiocarcinoma
Authors: Liu Guang-Jian , Wang Wei , Lu Ming-De , Xie Xiao-Yan , Xu Hui-Xiong , Xu Zuo-Feng , Chen Li-Da , Wang Zhu , Liang Jin-Yu , Huang Yang , Li Wei , Liu Jin-Ya
Published: October 2015

Purpose and methods: The ability of contrast-enhanced ultrasound (CEUS) to differentiate between hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) is still controversial. We reviewed the CEUS imaging of 819 patients (HCC=546, ICC=273) with an established pathological diagnosis. The enhancement patterns of lesions and the diagnostic performance of CEUS were analyzed. Results: Arterial hyperenhancement followed by washout was observed in 92.3% (504/546) of the HCC lesions and 85.7% (234/273) of the ICC lesions on CEUS (p<0.05). Additionally, the ICCs presented contrast washout much earlier than the HCCs, with an average time of 27.5 seconds after injecting the contrast agent compared with 70.1 seconds for the HCCs (p<0.05). Peripheral rim-like enhancement was observed in 68.5% (187/273) of the ICCs, which was significantly more common than that in the HCCs (2.0%, 11/546) (p<0.05). When using arterial hyperenhancement with a washout phase later than 43 seconds after injecting the contrast agent and with no peripheral rim-like enhancement as the diagnostic criteria for HCC ≤5 cm in diameter, the area under the curve was 0.808, with 64.1% sensitivity, 97.4% specificity and 73.6% accuracy. Conclusions: Although ICC may show the typical enhancement pattern of HCC on CEUS, peripheral rim-like enhancement and quick contrast washout show high efficiency in the differentiation of HCC from ICC.
Image-Guided Ablation of Malignant Liver Tumors: Recommendations for Clinical Validation of Novel Thermal and Non-Thermal Technologies - A Western Perspective
Authors: Lencioni Riccardo , de Baere Thierry , Martin Robert C. , Nutting Charles W. , Narayanan Govindarajan
Published: October 2015

Background: Image-guided ablation is used to treat patients with unresectable malignant hepatic tumors that are limited in number and size, especially hepatocellular carcinoma (HCC) and colorectal hepatic metastases. While radiofrequency ablation (RFA) has been the most popular technique, several alternate options for focal tissue destruction have recently attracted attention. These technologies appear to be able to overcome some specific limitations of RFA. Currently, there is no accepted algorithm for the use of the different techniques for image-guided ablation. Summary: A panel of physicians practicing in North America or Europe met to develop a set of recommendations aimed at providing directions for clinical validation of energy-based, thermal and non-thermal image-guided ablation technologies in the treatment of malignant liver tumors. The recommendations were developed through a critical appraisal of potential advantages and disadvantages of each ablation technology, based on experimental findings and available data, as well as on critical considerations for their clinical validation in hepatic tumor treatment from a Western perspective. Key Messages: Significant variability appears to exist among the different equipment and devices within each type of technology. A comprehensive understanding of the data and a critical appraisal of the efficacy and safety profile of each ablation system is required. Clinical practice guidelines should include specific information of the recommended techniques and protocols instead of a generic indication of the technology.
Behind the Link between Copper and Angiogenesis: Established Mechanisms and an Overview on the Role of Vascular Copper Transport Systems
Authors: Urso Emanuela , Maffia Michele
Published: October 2015

Angiogenesis critically sustains the progression of both physiological and pathological processes. Copper behaves as an obligatory co-factor throughout the angiogenic signalling cascades, so much so that a deficiency causes neovascularization to abate. Moreover, the progress of several angiogenic pathologies (e.g. diabetes, cardiac hypertrophy and ischaemia) can be tracked by measuring serum copper levels, which are being increasingly investigated as a useful prognostic marker. Accordingly, the therapeutic modulation of body copper has been proven effective in rescuing the pathological angiogenic dysfunctions underlying several disease states. Vascular copper transport systems profoundly influence the activation and execution of angiogenesis, acting as multi-functional regulators of apparently discrete pro-angiogenic pathways. This review concerns the complex relationship among copper-dependent angiogenic factors, copper transporters and common pathological conditions, with an unusual accent on the multi-faceted involvement of the proteins handling vascular copper. Functions regulated by the major copper transport proteins (CTR1 importer, ATP7A efflux pump and metallo-chaperones) include the modulation of endothelial migration and vascular superoxide, known to activate angiogenesis within a narrow concentration range. The potential contribution of prion protein, a controversial regulator of copper homeostasis, is discussed, even though its angiogenic involvement seems to be mainly associated with the modulation of endothelial motility and permeability.
Cognitive Function and 3-Tesla Magnetic Resonance Imaging Tractography of White Matter Hyperintensities in Elderly Persons
Authors: Reginold William , Luedke Angela C. , Tam Angela , Itorralba Justine , Fernandez-Ruiz Juan , Reginold Jennifer , Islam Omar , Garcia Angeles
Published: October 2015

Background/Aims: This study used 3-Tesla magnetic resonance imaging (MRI) tractography to determine if there was an association between tracts crossing white matter hyperintensities (WMH) and cognitive function in elderly persons. Methods: Brain T2-weighted fluid-attenuated inversion recovery (FLAIR) and diffusion tensor MRI scans were acquired in participants above the age of 60 years. Twenty-six persons had WMH identified on T2 FLAIR scans. They completed a battery of neuropsychological tests and were classified as normal controls (n = 15) or with Alzheimer's dementia (n = 11). Tractography was generated by the Fiber Assignment by Continuous Tracking method. All tracts that crossed WMH were segmented. The average fractional anisotropy and average mean diffusivity of these tracts were quantified. We studied the association between cognitive test scores with the average mean diffusivity and average fractional anisotropy of tracts while controlling for age, total WMH volume and diagnosis. Results: An increased mean diffusivity of tracts crossing WMH was associated with worse performance on the Wechsler Memory Scale-III Longest Span Forward (p = 0.02). There was no association between the fractional anisotropy of tracts and performance on cognitive testing. Conclusion: The mean diffusivity of tracts crossing WMH measured by tractography is a novel correlate of performance on the Wechsler Memory Scale-III Longest Span Forward in elderly persons.
Thulium Vaporesection of the Prostate and Thulium Vapoenucleation of the Prostate in Patients on Oral Anticoagulants: A Retrospective Three-Centre Matched-Paired Comparison
Authors: Netsch Christopher , Magno Carlo , Butticè Salvatore , Macchione Luciano , Mucciardi Giuseppe , Herrmann Thomas R.W. , Gross Andreas J.
Published: October 2015

Introduction: To evaluate the short-term results of thulium vaporesection of the prostate (ThuVEP) and thulium vapoenucleation of the prostate (ThuVARP) in patients with benign prostatic obstruction on oral anticoagulants (OA). Methods: A 3-centre retrospective matched-paired comparison of patients treated by ThuVEP (n = 26) or ThuVARP (n = 26) was performed. Thirty-four patients were on aspirin/ticlopidin, 7 on clopidogrel or clopidogrel and aspirin, and 11 on phenprocoumon at the time of surgery. Results: Haemoglobin decrease was higher after ThuVEP compared to ThuVARP (1.5 vs. 0.3 g/dl, p < 0.001). The rate of postoperative blood transfusions (3.9 vs. 0%), clot retention (3.9 vs. 0%), and re-operation (7.7 vs. 0%) was not different between ThuVEP and ThuVARP (p = 0.274). Catheterization time was shorter for ThuVARP (1 vs. 2 days, p < 0.01). Qmax was significantly higher after ThuVEP at 6-month follow-up (31 vs. 21.5 ml/s, p < 0.001), while improvements in International Prostate Symptom Score, quality of life, and post-voiding residual urine showed no differences between the groups. Urethral or bladder neck strictures did not occur during the 6-month follow-up in both groups. Conclusions: ThuVEP and ThuVARP are safe and efficacious procedures in patients on OA. Although patients assigned to ThuVEP had higher Qmax at 6-month follow-up, ThuVARP resulted in similar functional outcomes.
Large-Cell Neuroendocrine Carcinoma of the Esophagus: A Case from Saudi Arabia
Authors: Kuriry Hadi , Swied Abdul Monem
Published: October 2015

Neuroendocrine carcinomas of the esophagus are very rare, and the majority are high grade (poorly differentiated). They occur most frequently in males in their sixth and seventh decades of life. There have been no concrete data published on clinical features or on prognosis. We report a case of large-cell neuroendocrine carcinoma of the esophagus in a 66-year-old Saudi female with progressive dysphagia and weight loss. Upper endoscopy revealed an esophageal ulcerated mass.
Colorectal Liver Metastasis, Primary Gallbladder Carcinoma and Myelofibrosis Present Simultaneously in a Liver Resection Specimen
Authors: Gray Sophie A. , Raber Menno H. , Provoost Esther , Toes Gert-Jan , Klaase Joost M.
Published: October 2015

Myelofibrosis and gallbladder carcinoma are both very rare diseases. This case report describes a patient with a history of myelofibrosis and colorectal carcinoma who was diagnosed with colorectal liver metastases. Surgery was performed to remove the metastases, and on site, the gallbladder was removed because of involvement in one of the liver lesions. After pathological examination, a primary gallbladder carcinoma and myelofibrosis were found in addition to the liver metastases. The combination of diseases was not likely to be interconnected but rather an unlucky course of events for the patient.
I
Kr
Impact on Repolarization and Its Variability Assessed by Dynamic Clamp
Authors: Altomare Claudia , Bartolucci Chiara , Sala Luca , Bernardi Joyce , Mostacciuolo Gaspare , Rocchetti Marcella , Severi Stefano , Zaza Antonio
Published: October 2015

Background—

Repolarization and its stability are exquisitely sensitive to
I
Kr
features. Information on the relative importance of specific
I
Kr
abnormalities is missing and would assist in the evaluation of arrhythmogenic risk.

Methods and Results—

In single guinea-pig myocytes, endogenous
I
Kr
was replaced by modeled
I
Kr
(m
I
Kr
) by dynamic clamp (DC) at a cycle length of 1 s. m
I
Kr
parameters were systematically modified, and the resulting changes in action potential duration (APD) and its short term variability (SD1) were measured. We observed that (1)
I
Kr
blockade increased SD1 more than expected by its dependency on APD; (2) m
I
Kr
completely reversed APD and SD1 changes caused by
I
Kr
blockade; (3) repolarization was most sensitive to inactivation shifts, which affected APD and SD1 concordantly; (4) activation shifts of the same magnitude had marginal impact on APD, but only when reducing m
I
Kr
, they significantly increased SD1; (5) changes in maximal conductance resulted in a pattern similar to that of activation shifts.

Conclusions—

The largest effect on repolarization and its stability are expected from changes in
I
Kr
inactivation. APD is less sensitive to changes in other
I
Kr
gating parameters, which are better revealed by SD1 changes. SD1 may be more sensitive than APD in detecting
I
Kr
-dependent repolarization abnormalities.
Coexistent Types of Atrioventricular Nodal Re-Entrant Tachycardia
Authors: Katritsis Demosthenes G. , Marine Joseph E. , Latchamsetty Rakesh , Zografos Theodoros , Tanawuttiwat Tanyanan , Sheldon Seth H. , Buxton Alfred E. , Calkins Hugh , Morady Fred , Josephson Mark E.
Published: October 2015

Background—

There is evidence that atypical fast–slow and typical atrioventricular nodal re-entrant tachycardia (AVNRT) do not use the same limb for fast conduction, but no data exist on patients who have presented with both typical and atypical forms of this tachycardia. We compared conduction intervals during typical and atypical AVNRT that occurred in the same patient.

Methods and Results—

In 20 of 1299 patients with AVNRT, both typical and atypical AVNRT were induced at electrophysiology study by pacing maneuvers and autonomic stimulation or occurred spontaneously. The mean age of the patients was 47.6±10.9 years (range, 32–75 years), and 11 patients (55%) were women. Tachycardia cycle lengths were 368.0±43.1 and 365.8±41.1 ms, and earliest retrograde activation was recorded at the coronary sinus ostium in 60% and 65% of patients with typical and atypical AVNRT, respectively. Thirteen patients (65%) displayed atypical AVNRT with fast–slow characteristics. By comparing conduction intervals during slow–fast and fast–slow AVNRT in the same patient, fast pathway conduction times during the 2 types of AVNRT were calculated. The mean difference between retrograde fast pathway conduction during slow–fast AVNRT and anterograde fast pathway conduction during fast–slow AVNRT was 41.8±39.7 ms and was significantly different when compared with the estimated between-measurement error (
P
=0.0055).

Conclusions—

Our data provide further evidence that typical slow–fast and atypical fast–slow AVNRT use different anatomic pathways for fast conduction.