bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A38: A functional connection between the SWI/SNF-BAF ATPase BRG1 and the tumor suppressor BRCA1 in DNA damage response
Authors: Zhang Ling , Chen Hua , Gong Feng
Published: August 2014

We and others have shown that the SWI/SNF (BAF) chromatin remodeling complex plays a role in the repair of UV-induced DNA damage. It was proposed that chromatin remodeling activities are utilized to increase the accessibility of NER machinery and checkpoint factors to the damaged DNA. It was demonstrated recently that BRCA1 contributes to UV damage response by promoting photoproduct excision, triggering post-UV checkpoint activation and post replicative repair. In this study, we show that BRCA1 rapidly binds to UV damage sites when cells are undergoing DNA synthesis. In contrast, two phosphorylated forms of BRCA1 do not accumulate at sites of UV damage. Depletion of BRG1, a core subunit of the human SWI/SNF-BAF complex, impairs the recruitment of BRCA1 to the damage sites and attenuates DNA damage induced BRCA1 phosphorylation. At UV lesions-stalled replication forks, BRG1 promotes RPA phosphorylation in response to UV irradiation, since UV-induced phosphorylation of chromatin bound RPA drops significantly when BRG1 is depleted in human cells. In addition, activation of ATR/ATM is attenuated when BRG1 is depleted. We propose that BRG1 functions upstream of BRCA1 and modulates its response to UV irradiation.

Citation Format: Ling Zhang, Hua Chen, Feng Gong. A functional connection between the SWI/SNF-BAF ATPase BRG1 and the tumor suppressor BRCA1 in DNA damage response. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Jun 19-22, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2013;73(13 Suppl):Abstract nr A38.
Abstract A56: H3K9me3-based ChIP-seq analysis unveils global reprogramming in Cyclin D1-driven cellular senescence
Authors: Harajly Mohammad , Ghanem Noel , Saab Raya
Published: August 2014

Senescence is a permanent G1 cell-cycle arrest that can be triggered by acute stresses such as activated oncogenes and chemotherapeutic agents, and serves as a barrier to cancer development. Senescent cells exhibit distinct chromatin features compared with proliferating cells, known as senescence-associated heterochromatin foci (SAHF). These foci are enriched with histone H3 trimethylated at lysine 9 (H3K9me3), and are thought to impose a repressive state on regional genes. We performed genome-wide identification of elements associated with H3K9me3 by ChIP-seq technology, using an in vivo model of senescent pineal cells driven by Cyclin D1 oncogenic signaling, and compared them to non-senescent (Cyclin D1 expressing but p53-null) counterparts. We identified a set of genes whose H3K9me3 enrichment level was significantly changed (>2-fold). We also analyzed gene expression profiles on Affymetrix transcriptome chips. We found that about 50% of genes associated with H3K9me3 exhibited significant reduction in expression, while other genes were either upregulated or showed no change in expression. Gene ontology analysis clustered the genes into several functional groups, including cell-cycle control, transcription regulation, protein metabolism, cellular differentiation, and cellular adhesion. Notably, the gene ontology clustering showed that genes associated with H3K9me3 in senescent cells clustered into distinctly different functional programs than those associated with H3K9me3 in cells that had bypassed senescence. Our data indicate that chromatin changes in cellular senescence are informative regarding a distinct functional phenotype of the senescent condition. The mechanisms by which such changes contribute to tumor suppression are under active investigation.

Citation Format: Mohammad Harajly, Noel Ghanem, Raya Saab. H3K9me3-based ChIP-seq analysis unveils global reprogramming in Cyclin D1-driven cellular senescence. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Jun 19-22, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2013;73(13 Suppl):Abstract nr A56.
Abstract B05: The tumor suppressor gene pten regulates gene expression through histone H3.3 deposition and Daxx interaction
Authors: Benitez Jorge A. , Cavenee Webster K. , Furnari Frank B.
Published: August 2014

Sustaining proliferation is one of many capabilities acquired during tumor progression, where the PI3-kinase signaling pathway is a positive regulator of this trait and the tumor suppressor gene PTEN (phosphatase and tensin homology, deleted on chromosome ten) a negative regulator. Since PTEN deregulation is a central component of cancer progression, we decided to investigate how PTEN post-translational modifications modulate its function and protein interactions. We found that the histone chaperon protein Daxx (death domain-associated protein) associates with PTEN, in vivo and in vitro, and regulates PTEN stability through acetylation and ubiquitination. Moreover, we observed that PTEN regulates Histone 3.3 (H3.3 variant) deposition in the chromatin, by limiting Daxx interactions. We found an elevated H3.3-Daxx association in pten null cells, compared with pten-wt cells, correlating with a low H3.3 enrichment in the promoter of some driver tumor genes (Fos, Myc, Cyclin D1 and Bcl2) and an increased gene expression of them. We further demonstrated that this indirect gene expression regulation by PTEN is independent of its lipid-phosphatase activity. In conclusion, we hypothesize that PTEN may be mediating its tumor suppression function in part by regulating H3.3 deposition, and gene expression, through Daxx interaction.

Citation Format: Jorge A. Benitez, Webster K. Cavenee, Frank B. Furnari. The tumor suppressor gene pten regulates gene expression through histone H3.3 deposition and Daxx interaction. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Jun 19-22, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2013;73(13 Suppl):Abstract nr B05.
Abstract B25: DNA hypermethylation in prostate cancer is a consequence of aberrant epithelial differentiation and hyperproliferation
Authors: Pellacani Davide , Kestoras Dimitra , Droop Alastair P. , Frame Fiona M. , Berry Paul A. , Lawrence Mitchell G. , Stower Michael J. , Simms Matthew S. , Mann Vincent M. , Collins Anne T. , Risbridger Gail P. , Maitland Norman J.
Published: August 2014

Prostate cancer (CaP) is mostly composed of differentiated luminal cells, but contains a small subpopulation of undifferentiated basal cells (including stem-like cells), which is thought to be the driving force of CaP. In cancers, CpG island hypermethylation has been associated with gene downregulation, but the causal relationship between the two phenomena is still debated. This study aimed to understand the function and origin of CpG island hypermethylation in CaP, in the context of cancer hierarchy and differentiation. We have analyzed separately primary prostate basal and luminal cells derived from BPH and CaP. This allowed us to dissect the intra-tumor heterogeneity, and to understand the origin of gene downregulation and hypermethylation in CaP. We report that a set of genes commonly hypermethylated in CaP (including GSTP1) is: (i) downregulated as a result of prostate-specific epithelial differentiation in both CaP and benign prostatic hyperplasia (BPH); (ii) selectively hypermethylated in differentiated (luminal) cancer cells, process promoted by the hyperproliferating phenotype of these cells; (iii) actively expressed and methylation free in undifferentiated (basal) CaP cells. Downregulation and hypermethylation of these genes is not essential for tumor development or tumor expansion. Moreover, for all these genes, downregulation induced by prostate-specific differentiation, is independent of DNA hypermethylation, and is associated with detachment of RNA PolII from their promoter and reduction in histone marks associated with active transcription.

Citation Format: Davide Pellacani, Dimitra Kestoras, Alastair P. Droop, Fiona M. Frame, Paul A. Berry, Mitchell G. Lawrence, Michael J. Stower, Matthew S. Simms, Vincent M. Mann, Anne T. Collins, Gail P. Risbridger, Norman J. Maitland. DNA hypermethylation in prostate cancer is a consequence of aberrant epithelial differentiation and hyperproliferation. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Jun 19-22, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2013;73(13 Suppl):Abstract nr B25.
Abstract B30: Class I HDACs are mediators of smoke-carcinogen induced stabilization of DNMT1 and serve as promising targets for chemoprevention of lung cancer
Authors: Brodie Seth A. , Li Ge , El-Kommos Adam , Ramalingam Suresh S. , Behera Mahdusmita , Kowalski Jeanne , Gandhi Khanjan , Khuri Fadlo H. , Vertino Paula , Brandes Johann C.
Published: August 2014

Introduction: Epigenetic alterations have been identified as key events in the pathogenesis of non-small cell lung cancer (NSCLC). Previous studies have shown that smoke carcinogen exposure leads to increases in DNA-methyltransferase (DNMT1) protein expression, and subsequent epigenetic alteration - mediating early bronchial carcinogenesis. DNMT1 protein turnover is regulated by posttranslational modifications such as acetylation, phosphorylation and methylation. In lung cancer, increased levels of type I histone deacetylases (HDACs) HDAC1 and HDAC3 have been associated with poor outcomes. Clinically, HDAC inhibitors have shown promise for the treatment of advanced NSCLC.

Methods: In this study we use carcinogen exposed bronchial epithelial cells as a model of early carcinogenesis. We assayed these cells using various methods including soft-agar assays, methylation specific PCR and methylation array, siRNA knockdown, immunoblotting, co-immunoprecipitation and qPCR. We also analyzed a cohort of patient samples for expression of DNMT1 and HDACs by IHC.

Results: In this study, we describe that a close interaction between DNMT1 and class I histone deacetylases (HDAC)s after carcinogen exposure and in human lung cancer samples. We show that this interaction is associated with DNMT1 protein stabilization, can be disrupted with HDAC inhibition, and that HDAC inhibition leads to a loss of DNMT1 protein levels through an acetylation driven mechanism.

Conclusions: HDAC inhibition acts to epigenetically reprogram carcinogen exposed epithelia in part by blocking HDAC-DNMT1 interaction, thereby forcing the degradation of DNMT1. This highlights a possible role of HDAC inhibitors for the chemoprevention of lung cancer.

Citation Format: Seth A. Brodie, Ge Li, Adam El-Kommos, Suresh S. Ramalingam, Mahdusmita Behera, Jeanne Kowalski, Khanjan Gandhi, Fadlo H. Khuri, Paula Vertino, Johann C. Brandes. Class I HDACs are mediators of smoke-carcinogen induced stabilization of DNMT1 and serve as promising targets for chemoprevention of lung cancer. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Jun 19-22, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2013;73(13 Suppl):Abstract nr B30.
Abstract B36: DNA methylation profiling describes Wilms tumor evolution from its precursor lesion
Authors: Charlton Jocelyn , Williams Richard , Alcaide-German Marisa , Sebire Neil , Popov Sergey , Pritchard-Jones Kathy , Beck Stephan
Published: August 2014

Wilms tumor (WT) is the most common pediatric renal cancer and represents a model of disruption in kidney development with observed lesions of undifferentiated embryonic kidney termed nephrogenic rests (NR) which are considered precursor lesions. Epigenetic dysregulation plays a large part in Wilms tumorigenesis as dysregulation of IGF2/H19 is the most common aberration observed in ~70% WT.

To provide new insights into the molecular evolution of WT from its precursor lesions, genome-wide CpG methylation, which has frequently been shown to alter gene expression in cancer, was studied using the Illumina HumanMethylation 450 BeadChip array. Matched normal kidney (NK), NR and WT were sampled from 30 patient nephrectomies. To ensure precise microdissection, DNA was extracted from formalin-fixed paraffin embedded tissue after histological analysis.

Analysis of methylation β-values revealed an increase in methylation variability in both the NR and WT tissue. Linear modeling further supported the role of NR as a precursor lesion however showed that, although morphologically similar to embryonic kidney, the NR tissue is a unique entity. Furthermore, drastic epigenetic restructuring is observed in NR tissue including large regions of hyper- and hypomethylation previously associated with cancer tissue. This novel data suggests the NR has a cancer-like methylome. Further changes in DNA methylation were observed upon evolution of NR to WT. These ‘late event' methylation variable positions have the potential to be developed into an assay for differential detection of NR or WT in diagnostically challenging cases.

These results lead us to propose that during Wilms tumorigenesis, NR are prevented from completing nephrogenesis and continue divergent evolution into a separate entity distinct from the embryonic kidney. These NR are precancerous lesions that then evolve into WT.

Citation Format: Jocelyn Charlton, Richard Williams, Marisa Alcaide-German, Neil Sebire, Sergey Popov, Kathy Pritchard-Jones, Stephan Beck. DNA methylation profiling describes Wilms tumor evolution from its precursor lesion. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Jun 19-22, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2013;73(13 Suppl):Abstract nr B36.
Abstract B56: DNA demethylation in gene bodies is of therapeutic significance
Authors: Zhang Han Han , Yang Xiaojing , Carvalho Daniel D. De , Jones Peter A. , Liang Gangning
Published: August 2014

Reversal of aberrant promoter hypermethylation and associated gene silencing has been the primary focus of epigenetic therapy. Recently, gene body methylation has been implicated as having a functional role in the regulation of gene expression; however it is unclear how gene body methylation changes might contribute to the therapeutic effects of epigenetic therapy. To investigate the role of DNA demethylation in inducing gene expression changes in a comprehensive way, we treated the HCT116 colon cancer cell line with 5-Aza-2′-deoxycytidine (5-Aza-CdR) transiently for 24 hours and monitored changes in gene expression and DNA methylation levels at gene bodies and promoters for up to 42 days after treatment using 450K Infinium DNA methylation arrays and expression arrays. We observed that probes that became demethylated and subsequently regained methylation did at different rates. As we expected, demethylation of methylated promoters is negatively correlated with expression (R2≤ -0.75) and considerable demethylation of promoters (485) and the associated gene reactivation could be maintained for up to 42 days after drug treatment. Most of these genes are de novo methylated and their expression is down-regulated in primary colon cancers in the TCGA database. Strikingly, a group of genes shows a positive correlation between demethylation of gene bodies and down-regulation of gene expression after treatment (R2≥ 0.75). Four hundred ninety eight have fast rebound methylation kinetics and decreased expression and they are enriched for genes involved in metabolic process which are over-expressed in primary colon cancer tissues. Furthermore, 494 genes with sustained down-regulation of gene expression maintained their demethylated status and those are enriched for de novo methylation targets and over-expressed genes in colon cancer.

Our results demonstrate that DNA demethylation at gene bodies induced by 5-Aza-CdR can be of therapeutic significance by resulting in the down-regulation of genes that are overexpressed in cancers. Our findings also confirm that demethylation treatment could potentially cause prolonged reactivation of genes that are silenced by promoter methylation while simultaneously down-regulating genes that are overexpressed and have body methylation. Together, demethylation of gene bodies may confer therapeutic benefit in addition to demethylation of gene promoters.

Citation Format: Han Han Zhang, Xiaojing Yang, Daniel D. De Carvalho, Peter A. Jones, Gangning Liang. DNA demethylation in gene bodies is of therapeutic significance. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Jun 19-22, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2013;73(13 Suppl):Abstract nr B56.
Abstract PR08: mSWI/SNF (BAF) complexes facilitate decatentation of DNA by topoisomerase IIα
Authors: Dykhuizen Emily , Hargreaves Diana , Miller Erik , Cui Kairong , Korshunov Andrey , Kool Marcel , Pfister Stefan , Cho Yoon-Jae , Zhao Keji , Crabtree Gerald
Published: August 2014

Recent exon sequencing studies of human tumors have revealed frequent mutations in subunits of BAF (mSWI/SNF) complexes. Here we find a novel function for BAF complexes in decatenating newly replicated sister chromatids, which is necessary for proper chromosome segregation during mitosis. We find that deletion of Brg1 leads to anaphase bridge formation and stalling in G2/M phase. In addition, we find that Brg1 point mutants identified from medulloblastoma and Burkitt's lymphoma patients have compromised ATPase function and that their expression similarly results in G2/M arrest and anaphase bridge formation. The G2/M arrest is rescued by caffeine, a known inhibitor of ATM/ATR, key regulators of the decatenation checkpoint, and also by expression of the TopoIIα point mutant, S1524A, which fails to initiate the decatenation checkpoint. Endogenous BAF complexes directly interact with endogenous TopoIIα and are required for TopoIIα binding to about 12,000 sites over the genome. Similarly, cells expressing the oncogenic Brg1 point mutants have compromised TopoIIα binding at Brg1-dependent TopoIIα binding sites. These studies indicate that the ability of TopoIIα to prevent DNA entanglement at mitosis requires BAF complexes and suggest that this activity contributes to the role of Brg1 as a tumor suppressor.

This abstract is also presented as Poster A36.

Citation Format: Emily Dykhuizen, Diana Hargreaves, Erik Miller, Kairong Cui, Andrey Korshunov, Marcel Kool, Stefan Pfister, Yoon-Jae Cho, Keji Zhao, Gerald Crabtree. mSWI/SNF (BAF) complexes facilitate decatentation of DNA by topoisomerase IIα. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Jun 19-22, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2013;73(13 Suppl):Abstract nr PR08.
Abstract A04: HOXB13 regulates androgen receptor expression in prostate cancer
Authors: Chen Shuangling , Isaacs William B.
Published: August 2014

The androgen receptor (AR), a member of the nuclear receptor superfamily of ligand-regulated transcription factors, plays a pivotal role in the initiation and progression of prostate cancer. HOXB13, a prostate-specific homeodomain-containing transcription factor, interacts with AR to regulate the cellular response to androgens (Norris et al. Mol Cell 2009). The overexpression of HOXB13 in LNCaP and VCaP cells led to an increased expression of AR at the mRNA and protein levels; upon the reduction of endogenous HOXB13 by siRNA in LNCaP cells and VCaP cells, the amount of AR decreased at the mRNA and protein levels. Conversely, when AR was knocked down with siRNA in LNCaP cells, the level of HOXB13 proteins increased but not mRNA level, indicating that HOXB13 promotes the expression of AR, and AR promotes HOXB13 degradation. HOXB13 promoting AR expression might be one of the mechanisms by which HOXB13 regulates AR function.

Note: This abstract was not presented at the conference.

Citation Format: Shuangling Chen, William B. Isaacs. HOXB13 regulates androgen receptor expression in prostate cancer. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr A04.
Abstract A31: Regulation of ErbB4 receptor tyrosine kinase by the SUMO system
Authors: Korhonen Anna , Sundvall Maria , Vaparanta Katri , Elenius Klaus
Published: August 2014

The members of the ErbB family (EGFR/ErbB1, ErbB2, ErbB3, and ErbB4) of receptor tyrosine kinases (RTK) regulate key cellular processes including proliferation, differentiation, and survival, and play critical roles in several human malignancies. The alternatively spliced ErbB4 JM-a isoform was the first RTK found to signal by a mechanism involving proteolytic release of an intracellular receptor domain (ErbB4 ICD). The released ErbB4 ICD can translocate into the nucleus, where it functions as a transcriptional coregulator. ErbB4 ICD has been shown to regulate mammary epithelial development in vivo. Furthermore, nuclear ErbB4 immunoreactivity is frequently observed in clinical breast cancer samples. Although these findings suggest that ErbB4 signaling via ICD is biologically significant, little is known about the regulation of ErbB4 ICD functions or cellular localization.

We hypothesized that the soluble ErbB4 ICD is likely to be regulated by different mechanisms than the ones controlling conventional RTK signaling. One regulatory mechanism that is often employed by nuclear proteins is the small ubiquitin-like modifier (SUMO) system. SUMO proteins modify protein substrates covalently, and alter their function through changes in activity, stability, or cellular localization.

Here, we demonstrate that ErbB4 ICD is modified by SUMO-1 and SUMO-3. Full-length ErbB4 was not sumoylated, indicating that SUMO is a specific regulatory modification for the soluble ICD. By using site-directed mutagenesis followed by sumoylation assays, we mapped the major SUMO acceptor site in ErbB4. No differences were found between wild type and sumoylation deficient mutant of ErbB4 in biochemical assays measuring the tyrosine kinase activity of ErbB4, or activation of canonical RTK signaling pathways downstream of ErbB4. However, we showed that protein inhibitor of activated STAT3 (PIAS3), a SUMO E3 ligase that could stimulate the sumoylation, modulated the transcriptional coregulatory activity of ErbB4 ICD in luciferase reporter assays, as well as the function of ErbB4 ICD in mammary epithelial cell differentiation. Based on these findings we propose that the SUMO system regulates the nuclear signaling of ErbB4 ICD.

Citation Format: Anna Korhonen, Maria Sundvall, Katri Vaparanta, Klaus Elenius. Regulation of ErbB4 receptor tyrosine kinase by the SUMO system. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr A31.
Abstract A39: BACH1 and RKIP participate in a bistable network that affects progression to metastasis in breast Cancer
Authors: Lee Jiyoung , Yun Jieun , Yeung Kam , Bevilacqua Elena , Balázsi Gábor , Rosner Marsha Rich
Published: August 2014

The sources of nongenetic variability in metastatic progression are largely unknown. To address this question, we characterized a transcriptional regulatory network for the metastasis suppressor Raf Kinase Inhibitory Protein (RKIP). We previously showed that the transcription factor BACH1 is negatively regulated by RKIP, promotes breast cancer metastasis, and negatively correlates with RKIP expression in primary breast tumors. Here we demonstrate that BACH1 acts in a double negative (overall positive) feedback loop to inhibit RKIP transcription in breast cancer cells. BACH1 also negatively regulates its own transcription. HDAC inhibitors increased BACH1 but not RKIP transcription, whereas depletion of polycomb repressor EZH2 induced RKIP transcription. Analysis of the BACH1 network reveals the existence of a bistable, inverse relationship between BACH1 and RKIP that can potentially give rise to nongenetic variability. Together, our results suggest that the balance between RKIP and BACH1 plays a key role in determining metastatic progression in breast cancers.

Citation Format: Jiyoung Lee, Jieun Yun, Kam Yeung, Elena Bevilacqua, Gábor Balázsi, Marsha Rich Rosner. BACH1 and RKIP participate in a bistable network that affects progression to metastasis in breast Cancer. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr A39.
Abstract A40: CTEN prolongs EGFR signaling by reducing ligand-induced EGFR degradation
Authors: Hong Shiao-Ya , Shih Yi-Ping , Li Tianhong , Carraway Kermit , Lo Su Hao
Published: August 2014

Epidermal growth factor receptor (EGFR) tyrosine kinase engages a vast array of signaling pathways regulating tissue development and homeostasis. The signal is normally induced by ligand binding (such as EGF) that activates the receptors and then the downstream molecules, which mediate cell fate decisions such as proliferation, migration, and differentiation. EGF binding not only turns on the EGFR activity; it also turns on the mechanisms to inactivate EGFR signaling. One way is the activation of c-Cbl, an E3 ubiquitin ligase that binds to tyrosine-phosphorylated EGFR and leads to ubiquitination of EGFR for lysosomal degradation. Dysregulated EGFR signaling either by up-regulation or aberrant activation of the receptor will trigger cellular events that contribute to tumor microenvironments and cancer formation.

Focal adhesions connect extracellular matrix to cytoskeletal networks and play critical roles in cell adhesion, migration, proliferation, and survival. They also crosstalk with growth factor receptors, such as EGFR to elicit a wider range of cellular responses, and may function as biosensors for microenvironments. Cten (C-terminal tensin like) is a focal adhesion molecule known to regulate cell adhesion and migration. Previously, we had shown that cten was up-regulated by EGF and mediated EGF induced cell migration. To further investigate cten's role in EGFR signaling pathway, we examined cten's effect on EGFR protein stability. Cten significantly reduced ligand-induced EGFR degradation through decreasing EGFR ubiquitination. This was accomplished by binding to c-Cbl in a phosphotyrosine-SH2 dependent fashion. A functional SH2 domain of cten was essential for its activities in promoting tumor cell migration, invasion, and colony formation. In addition to cell culture systems, EGFR levels were markedly enhanced in a cten tissue-specific knockin mouse model. By analysis of cten and EGFR expressions in human cancer samples, we found a positive association between cten and EGFR protein levels. Since cten regulates the activated EGFR level and plays roles in tumor migration/invasion, targeting of cten might have a beneficial effect on EGFR targeted therapies.

Citation Format: Shiao-Ya Hong, Yi-Ping Shih, Tianhong Li, Kermit Carraway, Su Hao Lo. CTEN prolongs EGFR signaling by reducing ligand-induced EGFR degradation. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr A40.
Abstract A52: Loss of p120-catenin induces metastatic progression of breast cancer by inducing anoikis resistance and augmenting growth factor receptor signaling
Authors: Schackmann Ron C.J. , Klarenbeek Sjoerd , Vlug Eva J. , Stelloo Suzan , Amersfoort Miranda van , Tenhagen Milou , Braumuller Tanya M. , Vermeulen Jeroen F. , Groep Petra van der , Peeters Ton , Wall Elsken van der , Diest Paul J. van , Jonkers Jos , Derksen Patrick W.B.
Published: August 2014

The formation of metastasis is the most common cause of breast cancer-related death among women worldwide. A hallmark event in the dissemination of tumor cells from the primary tumor is the loss of cell-cell adhesion. Normally, epithelial integrity is controlled by the adherens junction (AJ), a membrane-tethered structure consisting of E-cadherin and its associated catenins αE-catenin, β-catenin and p120-catenin (p120). Loss of E-cadherin, which results in inactivation of the AJ, is strongly linked to tumor progression. However, little is known about the underlying mechanisms that drive tumor invasion and metastasis.

Since p120-catenin (p120) controls E-cadherin turnover at the cell membrane, we investigated the possible tumor suppressor functions of p120 in breast cancer. First, we analyzed a comprehensive set of invasive breast cancers using immunohistochemistry, and observed a lack of p120 protein expression in 33% (97/296). Next, we used a conditional mouse model of noninvasive (p53-driven) mammary carcinoma and introduced a conditional p120 allele. Combined loss of p120 and p53 resulted in tumors that resembled human metaplastic breast cancer and metastasize to lungs and lymph nodes. Knockdown of p120 in in anchorage-dependent breast cancer cell lines induces anoikis resistance by increasing sensitivity to growth factors. Interestingly, we observed secretion of inflammatory cytokines upon knockdown of p120. These cytokines likely underlie the formation of the prometastatic microenvironment in p120 negative mammary carcinomas, which in turn facilitate the production of growth factors. Finally, we performed RNA sequencing on p120-ablated cells and uncovered several highly up regulated growth factor receptors, which we will further examine to determine their eligibility as targets for intervention strategies to better treat p120-negative metastatic breast cancers.

Citation Format: Ron C.J. Schackmann, Sjoerd Klarenbeek, Eva J. Vlug, Suzan Stelloo, Miranda van Amersfoort, Milou Tenhagen, Tanya M. Braumuller, Jeroen F. Vermeulen, Petra van der Groep, Ton Peeters, Elsken van der Wall, Paul J. van Diest, Jos Jonkers, Patrick W.B. Derksen. Loss of p120-catenin induces metastatic progression of breast cancer by inducing anoikis resistance and augmenting growth factor receptor signaling. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr A52.
Abstract B01: Impacts of inulin on bile acids induced colon cancer
Authors: Afolabi Bene Akromaa , Appiah Sandra , Pachenari Azra , Ghali Lucy
Published: August 2014

Bile acids are normal components of the luminal contents of gastrointestinal tract but have been reported to cause oxidative damage by stimulating the generation of free oxygen radicals from the mitochondria. Several studies have demonstrated the contribution of reactive species to mutagenesis, carcinogenesis and tumor promotion. There is accumulating evidence to show that some carbohydrates and carbohydrate-containing molecules possess antioxidant ability by inhibiting the production of reactive species. Prebiotics are complex carbohydrates which have been shown to improve gut health when used in combination with probiotics. However, there is paucity of data on how prebiotics alone affect gut health and by which mechanism of action. The reactive oxygen scavenging ability of inulin, a prebiotic, has been shown in vitro in non-cell based system and in mice. The anti-inflammatory effect, through production of short chain fatty acids by fermentable inulin has also been shown. However, the mechanism of inulin in the amelioration of bile acid induced cancer remains unknown.

Methods: Three different cell-lines (colon stem cells, human colon carcinoma cells-HCT-116 and control normal colon epithelial cells) will be examined. Cells will be treated separately with secondary bile acids, primary bile acids and prebiotics. Cells will also be treated with microorganisms' filtrate such as probiotics (bifidobacteria) in conjunction with secondary bile acids, primary bile acids or prebiotics. Production of free radicals will be measured using nitro blue tetrazolium chloride assay (NBT) and inflammatory proteins will be measured using RT-PCR. DNA damage will be assessed using Endonuclease 111 enzyme modified Comet assay. In addition, C1 Single-Cell auto pep system will be used for mRNA sequencing of individual cells within the well plate.

This study hypothesized that normal cells exposed to secondary bile acids in the presence of inulin may be protected from transformation to cancer cells and this may correlate with decrease in production of reactive radicals and pro-inflammatory proteins. The anti inflammatory ability of short chain fatty acid and antioxidant ability of inulin may possibly be associated with AMP-activated protein kinase (AMPK), phosphatidylinositol 3-kinase (P13-K), NF-κB signaling pathways. Thus inulin and their fermentation/breakdown products may not only stimulate beneficial bacteria in the colon but may directly interfere with absorption and cellular metabolism processes in the colon.

Citation Format: Bene Akromaa Afolabi, Sandra Appiah, Azra Pachenari, Lucy Ghali. Impacts of inulin on bile acids induced colon cancer. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr B01.
Abstract B03: Stromal cells confer drug resistance to breast cancer cells in a kinetic co-culture model
Authors: Artymovich Katherine , Szybut Clare , Patel Kalpana , O'Callaghan Tim , Dale Tim , Trezise Del , Appledorn Daniel M.
Published: August 2014

The tumor microenvironment is fundamentally involved in the response of a tumor to anti-cancer therapies. In this study, we present a novel method for kinetically measuring the proliferation of one or more cell types in mixed, co-culture models. Specifically, lentiviral based reagents are used to label nuclei of multiple cell populations within a single culture. Real time cell counts are acquired using an automated, Live Content Imaging approach in which 96-well and 384-well microplates are imaged every 2-3 hours over the course of the full 2-3 day assay. Using this strategy, we confirm data illustrating that culturing HER-2 positive breast cancer cells (SK-BR-3) in the presence of either Human Mammary Fibroblasts (HMFs) or normal skin fibroblasts (CCD-1068Sk) are resistant to the anti-proliferative and cytotoxic effects of the HER-2 and EGFR tyrosine kinase inhibitor lapatinib. Extending this data, we also completed pharmacolgical analyses, using area under the curve of the full kinetic trace, revealing nearly a 2-log difference in lapatinib sensitivity between SK-BR-3 cells grown in the presence or absence lapatinib. The data presented here reveal a novel, automated, kinetic assay for measuring proliferation of one or more cell types in mixed culture models. More importantly, these data further clarify the pharmacolgical effect stromal cells can have on the resistance of breast cancer cells to lapatinib treatment.

Citation Format: Katherine Artymovich, Clare Szybut, Kalpana Patel, Tim O'Callaghan, Tim Dale, Del Trezise, Daniel M. Appledorn. Stromal cells confer drug resistance to breast cancer cells in a kinetic co-culture model. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr B03.
Abstract B28: Pro-survival role of p53 in regulating epidermal differentiation
Authors: Kracikova Martina , Akiri Gal , Aaronson Stuart A.
Published: August 2014

It is well established that in response to diverse stress signals, the p53 tumor suppressor prevents growth of abnormal cells by inducing senescence or apoptosis. However, recent studies have shown that p53 can contribute to pro-survival pathways such as innate immune response, metabolic regulation and antioxidant defense against reactive-oxygen species (ROS). Here we demonstrate a novel role of p53 in regulating an epidermal differentiation program. Using microarray and real-time PCR, we found that p53 activates the expression of genes within the human and mouse epidermal differentiation complex (EDC), including genes within the cornified envelope precursor family and the fused gene family. Chromatin immunoprecipitation and luciferase reporter assay demonstrated direct p53 binding and activation of a cornified envelope precursor gene. Activation of p53 by ultraviolet B (UVB) radiation or via nutlin-3 led to a dose-dependent increase in expression of those genes, and this increase was inhibited in cells with downregulated p53. The p53-dependent expression of the EDC genes was not limited to keratinocytes, but also detected in other cell types, suggesting additional functions of these genes normally attributed to keratinocyte differentiation and formation of the cornified envelope. These findings identify a novel p53-regulated differentiation pathway and suggest that differentiation may be another pro-survival component of its tumor suppressor function.

Citation Format: Martina Kracikova, Gal Akiri, Stuart A. Aaronson. Pro-survival role of p53 in regulating epidermal differentiation. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr B28.
Abstract B34: The impact of chromosome 17p loss on cancer
Authors: Liu Yu , Scuoppo Claudio , Lowe Scott
Published: August 2014

Chromosome 17p deletions are associated with short survival and poor response to current chemotherapy treatment in non-Hodgkin's lymphomas. Although the prevailing view is that these deletions serve as a “second hit” event to inactivate p53, these deletions often hundreds of other genes. Using an in vivo RNAi screening approach for tumor suppressor genes, we identified and validated two additional tumor suppressors adjacent to p53 suggesting these deletions may do more than merely inactivate p53. To test this hypothesis, we constructed a new mouse model conditionally targeting a broad region of 17p and are intending to investigate whether and how genes co-deleted with well-known tumor suppressor p53 affect lymphoma development and chemotherapy responses. These results will elucidate the aggressive nature of tumors harboring 17p deletions and create the first mouse model that can be used to test strategies to overcome its deleterious effects.

Citation Format: Yu Liu, Claudio Scuoppo, Scott Lowe. The impact of chromosome 17p loss on cancer. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr B34.
Abstract B62: Proteomic dynamics of stromal exosomes during processing in cancer cells
Authors: Underhill Ainsley Q. , Zhang Yingyi Amy , Zhang Liang , Luga Valbona , Wrana Jeff
Published: August 2014

Within the tumor microenvironment, cancer-associated fibroblasts (CAFs) are capable of releasing exosomes, small extracellular vesicles, which are then used by breast cancer cells to aid in metastasis. Exosomes are uptaken by the cancer cells and gain Wnt11 through processing, thus allowing them to stimulate Wnt-signaling pathways that causes increased cell motility. Our current research has focused on understanding the events that exosomes undergo as they pass through breast cancer cells. Exosomes from L cells carry the tetraspanin, Cd81, and two of its known transmembrane interactors Igsf8 and Ptgfrn. By using immunoprecipitation, we were able to isolate Cd81-exosomes, and analyze them by mass spectrometry. Furthermore, comparison of Cd81-exosomes before and after processing in MDA-MB-231, a human breast cancer cell line, revealed differences in protein content of the exosomes. Additionally, since L cells are a mouse fibroblast cell line, we could identify the origin of each protein based on variance between human and mouse proteins. Several families of proteins were identified, such as RNA-binding proteins, kinases, phosphatases, and secretory and endocytic proteins. Our data allows us to postulate that Cd81-exosome processing involves the use of the cancer cell endocytic and secretory pathways. By determining the mechanism whereby breast cancer cells use Cd81-exosomes as signals, it may be possible to block this process and prevent or slow metastatic events.

Citation Format: Ainsley Q. Underhill, Yingyi Amy Zhang, Liang Zhang, Valbona Luga, Jeff Wrana. Proteomic dynamics of stromal exosomes during processing in cancer cells. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr B62.
Abstract C07: Impact of human epidermal-growth-factor receptor-2 (HER2) expression and two BRCA1/2 pathogenic mutations with outcome of the breast cancer patients
Authors: Fiuji Hamid , Bibak Bahram , Maftouh Mina , Mirhafez Reza , Avan Amir
Published: August 2014

Background/Aim: Breast cancer is a major unsolved health problem with poor prognosis; thus, identification of prognostic biomarkers is warranted. The aim of present study was to 1) evaluate the prevalence of the common mutations in the BRCA1 (C61G) and BRCA2 (6174delT) genes in Iranian patients with breast cancer, 2) and to investigate the correlation of these mutation and also HER-2, P53 and Ki67 expression with clinical outcome of the patients treated with standard regimen chemotherapy.

Patients and methods: 168 patients, including eighty healthy volunteers, were selected for BRCA1/2 mutation screening. DNA was isolated from blood samples and then frequency of 6174delT and C61G were evaluated in the patients using amplication refractory mutation system (ARMS) PCR and also by sequencing of the related site of genes in positive patients. Expressions of HER2, P53 and Pi27 were evaluated by ELISA, and their correlations with clinical outcome were investigated. We also analyzed data on overall survival according to clinicopathological characteristics of the patients.

Results: Consistent with previous findings, our analysis resulted in the identification of concomitant germline BRCA1 and BRCA2 mutations in none of the patients. Moreover, the present of the mutations were explored and confirmed by sequencing analysis of the positive and control samples, as well as in none of the patient samples. Furthermore, high expression of HER-2 and Ki67 were found in 42 and 66% of the patients, respectively, and were associated with significantly shorter OS. HER2 expression was associated with risk of death (e.g., hazard ratio= 1.6; 95%CI, 1.1–2.3, P<0.05).

Conclusions: our results suggest that Iranian breast cancer patients represent the presence of additional kinds of BRCA1/2 alteration (such as genomic rearrangements/deletion) or by mutations on/different breast cancer related genes. However, ethnic background can also influence on prevalence of the mutations. These results prompt further studies as well as research on the biological role of these mutations in breast cancer. Nevertheless, larger multicenter studies are critical to explore the role of emerging biomarkers before planning of prospective trials.

Note: This abstract was not presented at the conference.

Citation Format: Hamid Fiuji, Bahram Bibak, Mina Maftouh, Reza Mirhafez, Amir Avan. Impact of human epidermal-growth-factor receptor-2 (HER2) expression and two BRCA1/2 pathogenic mutations with outcome of the breast cancer patients. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr C07.
Abstract C53: rVP1 inhibits prostate cancer metastasis via suppression of Jagged1
Authors: Wang Jui-Ling , Hung Shao-Wen , Liang Chi-Ming , Hsiao Pei-Wen , Liang Shu-Mei
Published: August 2014

Jagged1, a NOTCH ligand, has been shown to correlate with poor prognosis and metastasis of prostate cancer (CaP). CaP is a leading cause of cancer death among men worldwide. There is currently no effective therapeutic strategy for patients with castration-resistant prostate cancer (CRPC) which is defined as continued growth of CaP despite the suppression of male hormones. We previously reported that recombinant capsid protein VP1 (rVP1) of foot-and-mouth disease virus causes cell apoptosis of PC-3, a CRPC, via integrin β1 in vitro. Herein, we demonstrate that rVP1 inhibited cell migration/invasion at a non-toxic concentration and reduced the expression level of Jagged1 and phosphorylation of Akt (Ser 473) and IKKα/β (Ser 176/180) of PC-3 cells in vitro. This inhibition was abolished by integrin β1 blocking antibody, knockdown of integrin β1, or a constitutively active Akt. Furthermore, intravenous administration of rVP1 induced tumor apoptosis, suppressed tumor Jagged1 expression level, reduced primary-tumor spread to lymph nodes and bone, and prolonged the survival time of tumor-bearing mice in an orthotopic PC-3 xenograft model. Recombinant VP1 retarded tumor expansion within the bone and tumor-induced osteolysis in an experimental model of bone metastasis made by injecting PC-3 cells carrying the luciferase gene into mouse left ventricle. Finally, in vivo vascular permeability analyses showed that rVP1 specifically targeted tumor cells by penetrating leaky tumor vasculature. Recombinant VP1 may thus suppress Jagged1 expression of CaP cells by inhibiting the integrin β1/Akt/NF-κB signaling pathway to attenuate expansion of bone metastases and tumor-induced osteolysis in CRPC.

Citation Format: Jui-Ling Wang, Shao-Wen Hung, Chi-Ming Liang, Pei-Wen Hsiao, Shu-Mei Liang. rVP1 inhibits prostate cancer metastasis via suppression of Jagged1. [abstract]. In: Proceedings of the Third AACR International Conference on Frontiers in Basic Cancer Research; Sep 18-22, 2013; National Harbor, MD. Philadelphia (PA): AACR; Cancer Res 2013;73(19 Suppl):Abstract nr C53.