bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract B10: mTORC1 directly phosphorylates and activates ERα upon estrogen stimulation
Authors: Alayev Anya , Holz Marina K. 
Published: May 2016

Abstract
Approximately 75% of breast cancers are estrogen receptor (ERα) positive, underscoring the dependence of cancer cells on estrogen for growth and survival. Patients treated with endocrine therapy often develop resistance, either de novo or acquired, which is caused by aberrations within the growth factor signaling pathways. The mechanistic target of rapamycin complex 1 (mTORC1) has emerged as a critical node in estrogenic signaling. We have previously shown that mTORC1 can phosphorylate and activate ERα on S167 via its effector the 40S ribosomal S6 kinase 1 (S6K1). Presently, we have uncovered a direct link between mTORC1 and ERα. We found that ERα binds to regulatory-associated protein of mTOR (Raptor) and causes it to translocate to the nucleus upon estrogen stimulation. Additionally, we identified mTOR as the kinase that directly phosphorylates ERα and activates transcription of ER target genes. Our findings show a direct link between mTORC1 and ERα, which further implicates mTORC1 signaling in the pathogenesis of ER-positive breast cancer and provides additionale rationale for the FDA-approved use of mTORC1 inhibitors in combination with endocrine agents for treatment of this disease .
Citation Format: Anya Alayev, Marina K. Holz. mTORC1 directly phosphorylates and activates ERα upon estrogen stimulation. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr B10.
Abstract B30: Ex vivo culture of breast cancer patient-derived xenografts in modified 3-D hyaluronan hydrogels
Authors: Sablatura Lindsey K. , Kavuri MeghaShyam , Richards Priya , Harrington Daniel A. , Ellis Matthew J. , Farach-Carson Mary C. 
Published: May 2016

Abstract
The high attrition rate of potential anti-cancer drugs entering clinical trials indicates the need for more predictive pre-clinical model systems. Standard compound screening is high-throughput and relatively inexpensive, but conducted with non-representative cells in a non-physiological environment. Three-dimensional (3D) culture systems provide cells a more physiological microenvironment including relevant extracellular matrix (ECM) cues and cell-cell interactions. Patient-derived xenograft (PDX) culture preserves tumor heterogeneity while mitigating harsh selective pressures induced by traditional 2D culture methods. However, in vivo mouse models are slow and expensive, often with low “take” rates that limit the numbers of drugs and drug combinations that can be tested. Within the present study, we established the direct culture of breast cancer PDX cells in a hyaluronan-based hydrogel matrix that is amenable to automated dispensing. Washington University Human in Mouse (WHIM) breast cancer PDX tumors were dissociated and PDX cell were encapsulated in 3D hydrogels for in vitro culture. In vitro cultured PDX cells showed high viability over 7 days, as assessed by standard live/dead assay. Cell morphology and marker retention were also examined using immunofluorescence staining for markers including ER, EpCAM, and vimentin, and were found to be subtype-consistent. Ongoing studies seek to expand the PDX tumors in hydrogel matrices such that they may be useful for a variety of applications including drug screening, proteome and kinome activation analysis, and other applications that will enable the development of personalized therapies suited to individual breast cancer patients presenting with various disease subtypes.
Citation Format: Lindsey K. Sablatura, MeghaShyam Kavuri, Priya Richards, Daniel A. Harrington, Matthew J. Ellis, Mary C. Farach-Carson. Ex vivo culture of breast cancer patient-derived xenografts in modified 3-D hyaluronan hydrogels. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr B30.
Abstract B45: De novo generation of highly aggressive human breast tumors by rapid serial passaging of oncogene-transduced starting populations of purified normal cells
Authors: Lefort Sylvain , Pellacani Davide , Nguyen Long , Eaves Connie J. 
Published: May 2016

Abstract
Human breast cancers are clonal outgrowths that have diversified genetically and biologically by the time they are clinically evident. However, early events that predicate malignant transformation of normal human mammary epithelial cells and the importance of the specific cell type to first be altered has remained elusive. We have developed an in vivo system that allows analysis of the initial steps of tumorigenesis from defined subsets of normal human mammary cells within 8 weeks using a single (KRASG12D) or multiple oncogenes. Using a protocol in which we first isolate biologically, transcriptionally and phenotypically different human mammary cell types by FACS using EpCAM and CD49f or CD10 as distinguishing markers, and then transduce the cells with lentiviral constructs, and immediately transplant them into highly immunodeficient NOD/RAG1-/-IL2rγ-/- (NRG) female mice, we have found that invasive ductal carcinomas expressing a variety of basal and luminal-associated markers (such as CK5, CK8/18, EGFR and MUC1) can be obtained at high frequency from purified starting populations of both basal cells and luminal progenitors within 8 weeks. Many tumours could be passaged both in vivo and under multiple conditions in vitro (on collagen, in suspension “mammopshere” culture or 3D matrigel cultures). After only 4passages in vivo, an aggressive tumor cell line that is tumorigenic within 6 weeks in vivo at unit efficiency has emerged. Intravenous injections shown that these cells can colonize multiple organs including the lung, kidney and spleen. Molecular characterization of these aggressive tumors has established that they are EpCAM+ and CD44+. Additional examples of de novo tumors able to be serially passaged are now being characterized. This new tumorigenesis model will allow us to compare the sequential changes that accompany and underlie the full process of malignant progression and should thus enable key molecular determinants that drive cancer initiation and progression to be identified.
Citation Format: Sylvain Lefort, Davide Pellacani, Long Nguyen, Connie J. Eaves. De novo generation of highly aggressive human breast tumors by rapid serial passaging of oncogene-transduced starting populations of purified normal cells. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr B45.
Abstract B52: Overcoming phenotypic heterogeneity and plasticity in basal-like breast cancer through targeting adaptive pathway use
Authors: Risom Tyler , Langer Ellen , Rantala Juha , Alvarez Mariano , Johnson-Camacho Katie , Pelz Carl , Wang Nicholas , Spellman Paul , Califano Andrea , Gray Joe , Sears Rosalie 
Published: May 2016

Abstract
The use of small-molecule kinase inhibitors is a promising therapeutic strategy for the management of breast cancer. Positive responses to these agents, however, are often transient, and acquired resistance arises in the course of weeks to months. Recent studies have demonstrated that phenotypic plasticity in cancer cell populations can provide adaptive resistance to small-molecule kinase inhibitors, whereby cancer cells transition to drug-tolerant phenotypic states, reliant on compensatory survival and proliferative signaling pathways. Drug combinations and sequences can prevent this adaptive resistance to targeted therapy, however, nominating effective drug pairs is challenging. In this study, we seek to identify such drug combinations through first identifying single agent therapeutics that reduce phenotypic heterogeneity and enrich distinct cell-states with common pathway reliance. To do so, we focus on phenotypic heterogeneity in tumor-cell lineage-state; using immunofluorescent staining against markers of the luminal, basal, and mesenchymal lineages, we combine high-throughput drug screening with high-content imaging and pursue small-molecule inhibitors that reduce phenotypic heterogeneity and promote the accumulation of particular lineage-states in residual cell populations. We observe pronounced lineage-state heterogeneity in Triple-Negative tumors and Basal-Like breast cancer cell lines, and find that the lineage-state distributions are greatly influenced by numerous therapeutics. MEK and PI3K/mTOR inhibitors in particular induce robust time- and dose-dependent alterations is lineage-state distribution in residual cell populations, selecting for a cell population enriched in, or depleted of a basal lineage-state, respectively. Through gene expression profiling and master-regulator analysis of active transcriptional states in the residual cell populations, we are able to identify compensatory-signaling pathways. We demonstrate that combining MEK and PI3K/mTOR inhibitors with agents targeting these compensatory pathways induces synergistic antiproliferative effects.
Citation Format: Tyler Risom, Ellen Langer, Juha Rantala, Mariano Alvarez, Katie Johnson-Camacho, Carl Pelz, Nicholas Wang, Paul Spellman, Andrea Califano, Joe Gray, Rosalie Sears. Overcoming phenotypic heterogeneity and plasticity in basal-like breast cancer through targeting adaptive pathway use. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr B52.
Abstract B53: Genomic redefinition of Her2+ breast shows role of estrogen and androgen signaling
Authors: Daemen Anneleen , Rinaldi Jacob , Manning Gerard 
Published: May 2016

Abstract
Many breast cancers are driven by amplification and overexpression of the Her2 receptor tyrosine kinase. We searched the TCGA and Metabric genomic datasets to define and better understand the genetic drivers of Her2+ cancer. We defined Her2+ tumors as those with a ploidy-corrected copy number for Her2 of 4 or more, encompassing 12% of breast tumors in both cohorts. This population showed high concordance with Her2 IHC/FISH status, but weak concordance with intrinsic PAM50 subtype: 45% of Her2+ breast tumors were Her2-enriched, 48% luminal A or B, and 7% basal-like. We characterized this transcriptionally heterogeneous Her2+ population using a meta-consensus clustering approach. Her2 amplification--though a driver--had limited impact on the transcriptional profile of each tumor. Her2+ tumors were rather additionally driven by estrogen or androgen signaling, with their transcriptional subtype defined by ER, PR and AR status. In terms of copy number, Her2+ tumors showed biologic selectivity for oncogenes and putative driver genes located in 8 regions outside of the Her2 amplicon that were selectively aberrated in presence of Her2 amplification. We also identified a small population of breast tumors with substantial over-expression of Her2 and neighboring genes that lack amplification but show consistent hypo-methylation. In conclusion, considering the transcriptional profile of Her2+ breast tumors provides combination strategies and viable treatment options for patients who developed resistance to Her2-targeted treatments, with endocrine therapies for Her2+/ER+ tumors, and antiandrogen strategies for Her2+/AR+ tumors. Furthermore, co-ordinated regulation of Her2 and neighboring genes supports the notion that the effect of the Her2 amplicon may be more than through overexpression of Her2.
Citation Format: Anneleen Daemen, Jacob Rinaldi, Gerard Manning. Genomic redefinition of Her2+ breast shows role of estrogen and androgen signaling. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr B53.
Abstract B67: CD4 Th1 cytokines synergize with HER-2/HER-3 blockade to induce tumor senescence and apoptosis in both HER-2 sensitive and resistant breast cancer cells
Authors: Rosemblit Cinthia , Czerniecki Brian J. 
Published: May 2016

Abstract
Background: We have demonstrated there is a loss of anti-HER-2 Th1 response during tumorigenesis in HER-2pos breast cancer. Maintenance of this response is associated with complete response to neoadjuvant therapy and prolonged disease free survival. The CD4 Th1 or Th1 cytokines IFN-γ and TNF-α induce apoptosis and tumor senescence in HER-2pos breast cancer cells. In the current study we investigated whether combining Th1 cytokines with HER-2/HER-3 blockade would impact both HER-2 sensitive and resistant breast cancer cells.
Results: SK-BR-3 breast cancer cells exposed to HER2 Class II peptide-primed CD4+ T-cells cells in a transwell culture system confirmed that the cytokines produced by the CD4+ T cells induced senescence and apoptosis of the HER-2pos cells as measured by SA-β-galactosidase (gal) staining, increased expression of p15INK4b and cleaved caspase 3 detected by western blot. CD4+ T-cells primed either with immature dendritic cells (DCs) or mature DCs plus irrelevant Class II (BRAF or survivin) peptides were not able to induce senescence, nor apoptosis. The senescence and apoptosis observed was dramatically augmented in HER-2pos cells exposed to HER2 Class II peptide-primed CD4+ T-cells in presence of trastuzumab and pertuzumab in the transwell. HER-2 resistant cells HCC-1419 and JIMT-1 treated with IFN-γ and TNF-α demonstrated a dose dependent increase in senescence and apoptosis suggesting HER-2 resistant cell lines are sensitive to Th1 cytokine effects. Both breast cancer cell lines tested express IFN-γ and TNF-α receptors as measured by western blot analysis. Although trastuzumab and pertuzumab had little effect on induction of senescence or apoptosis in the resistant cells, the combination of Th1 cytokines with trastuzumab and pertuzumab induced similar levels of senescence measured by SA-β-gal assay and p15INK4b as well as effectively induced cell death by apoptosis to levels similar to those seen in HER-2 sensitive cell lines.
Conclusions: Our results establish a role for Th1 cytokines IFN-γ and TNF-α in inducing tumor senescence and apoptosis in both sensitive and resistant HER-2 expressing cells that is dramatically augmented by HER-2/HER-3 blockade. An effective CD4 Th1 response, combined with HER-2 and HER-3 blockade can significantly drive tumor senescence and apoptosis and should be readily explored as non-cross-reactive therapy to effectively eliminate residual cancer cells and prevent recurrence in HER-2pos breast cancer.
Citation Format: Cinthia Rosemblit, Brian J. Czerniecki. CD4 Th1 cytokines synergize with HER-2/HER-3 blockade to induce tumor senescence and apoptosis in both HER-2 sensitive and resistant breast cancer cells. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr B67.
Abstract IA15: Immune control of breast cancer metastasis
Authors: Welm Alana L. 
Published: May 2016

Abstract
Twenty to thirty percent of breast cancer patients eventually develop metastasis despite receiving state-of-the-art therapies. Clearly, identifying better ways to eliminate micro-metastatic tumor cells is paramount to eradicating death from breast cancer. We now know that every tumor is unique and that each tumor is heterogenous. Tumors hijack multiple, redundant pathways to survive and grow, and evolve resistance under selective pressure from therapy. Moreover, micro-metastatic cancer cells may be dormant and resistant to therapy. Thus, traditional approaches to treat cancer and prevent metastatic recurrences don't work for everyone.
Stimulating the immune system to kill cancer cells (known as immunotherapy) carries strong appeal: the response can be individualized; the immune system is effective against diverse pathogens (in this case, tumor antigens); and immunity can evolve and retain memory for long-term control of disease. The challenge is that by the time tumors are clinically detectable they are already ‘invisible’ to the immune system due to a number of factors: (1) natural selection for tumor cells that can escape immune control; (2) immune tolerance to self- and tumor-antigens; and (3) the strongly immunosuppressive environment in tumors, which renders effector cells inactive. A better understanding of how tumors achieve immune evasion will allow development of strategies to promote more effective anti-tumor immunity.
We have determined that Ron protein kinase activity in the host immune system is a major contributor to metastasis. This finding was unanticipated; the expected result was that blocking Ron signaling in tumor cells would inhibit tumor progression, which was the basis for development of Ron inhibitors by the pharmaceutical industry. Our work now shows that Ron inhibitors reduce metastasis through dual effects on tumor cells and on the immune system: Approximately 40% of human breast tumors upregulate the Ron ligand, which is secreted from the tumor, activates Ron on macrophages, and polarizes them to an immune suppressive state. Inhibiting Ron, either genetically or with drugs, blocks metastasis by activating an anti-tumor immune response mediated by CD8+ cytotoxic T lymphocytes (CTLs). Thus, inhibition of Ron boosts anti-tumor immunity and prevents metastasis. These data suggest that inhibition of Ron in the tumor microenvironment might provide a new, complementary strategy to ongoing immunotherapy. Thus, Ron inhibitors might serve as macrophage ‘checkpoint inhibitors’ to complement checkpoint inhibition in T-cells.
Citation Format: Alana L. Welm. Immune control of breast cancer metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr IA15.
Abstract PR01: Understanding the role of BCL11A in triple-negative breast cancer
Authors: Lazarus Kyren , Caldas Carlos , Liu Pentao , Khaled Walid T. 
Published: May 2016

Abstract
Triple-negative breast cancer (TNBC) has poor prognostic outcome compared to other subtypes of breast cancer. The molecular and cellular mechanisms underlying TNBC pathology are not fully understood. We analyzed both METABRIC and TCGA data found the transcription factor BCL11A is overexpressed in TNBC including basal-like breast cancer (BLBC) and that its genomic locus is amplified in up to 38% of BLBC tumors. Moreover, analysis of the TCGA data revealed that the BCL11A locus is hypo-methylated almost exclusively in BLBC tumors but not other subtypes. We show that exogenous BCL11A overexpression promotes tumor formation, whereas its knockdown in TNBC cell lines suppresses their tumorigenic potential in xenograft models. In the mouse DMBA-induced tumor model, Bcl11a deletion substantially decreases tumor formation, even in p53-null cells and inactivation of Bcl11a in established tumors causes their regression. At the cellular level, Bcl11a deletion causes a reduction in the number of mammary epithelial stem and progenitor cells. Mechanistically, proteomics studies have revealed that BCL11A interacts with a specific set of chromatin modifiers in tumor cells but not in normal cells - the significance of which is currently under investigation. This study highlights the potential for targeting BCL11A as an approach for TNBC-targeted therapy. To this end we are currently using the Crispr/Cas9 system to generate endogenous reporter cell lines for high-throughput drug screens to identify potential inhibitors of BCL11A.
Citation Format: Kyren Lazarus, Carlos Caldas, Pentao Liu, Walid T. Khaled. Understanding the role of BCL11A in triple-negative breast cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research; Oct 17-20, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(2_Suppl):Abstract nr PR01.
Abstract A11: N-Myc and STAT interactor (NMI): A regulator of developmental signaling and EMT
Authors: Samant Rajeev S. , Pruitt Hawley C. , Metge Brandon J. , Shevde Lalita A. 
Published: May 2016

Abstract
The NMI protein associates with known key transcription factors such as Myc and STATs and serves as a critical regulatory co-factor that dictates specialized functions. While a physiological function for NMI is yet unknown, it has potential roles in pathologies ranging from viral infection to cancer. We will present pioneering work from our laboratory showing that NMI impacts two major developmental signaling pathways - TGFβ and Wnt pathways.
EMT is one of the key phenomena underlying normal embryonic and organ development, with a vital role in metastatic progression. We discovered that the expression of NMI is significantly downregulated in metastatic breast tumors. We recapitulated this by stably silencing the expression of NMI in breast cancer cells. Abrogating NMI expression from epithelial-like breast cancer cells enabled cells to assume a mesenchymal-like phenotype. Detailed molecular and functional investigations revealed that this mesenchymal transition was facilitated by decreased STAT5 signaling that caused concomitant reduction in SMAD7 expression and manifestation of a TGFβ-driven EMT program.
In contrast, breast cancer cells restored for NMI expression showed autophagic vacuoles and LC3 processing. We found that NMI expression restricts Wnt/β-catenin signaling by upregulation of the secreted Wnt inhibitor, DKK1. Thus NMI prompts activation of GSK3-β, a key kinase upstream of the TSC1/TSC2 complex. Inhibition of GSK3-ββin NMI expressing cells activated mTOR signaling and decreased the cells’ autophagic response. Autophagy is a determinant of cellular survival through dormancy and cytotoxic drug insult. Rapid progression of autophagy leads to cell death. In agreement with our molecular analyses, we determined that abrogation of NMI expression rendered cells resistant to cisplatin and doxorubicin.
Our findings elicit interesting possibilities about the role of NMI in regulating EMT and autophagy. Evidence from our investigations strongly suggests that loss of NMI leading to aberrant activation of multiple developmental signaling pathways, may be a vital event in the progression of breast cancer characterized by reduced autophagy and stabilization of transcription factors that function as major drivers of EMT.
Citation Format: Rajeev S. Samant, Hawley C. Pruitt, Brandon J. Metge, Lalita A. Shevde. N-Myc and STAT interactor (NMI): A regulator of developmental signaling and EMT. [abstract]. In: Proceedings of the AACR Special Conference: Developmental Biology and Cancer; Nov 30-Dec 3, 2015; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(4_Suppl):Abstract nr A11.