bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract A036: Integrin αvβ3 drives the mammary stem cell state during pregnancy
Authors: Desgrosellier Jay , Lesperance Jacqueline , Seguin Laetitia , Shattil Sanford , Cheresh David 
Published: May 2015

Abstract
Epithelial stem/progenitor cell properties are associated with aggressive carcinomas. The integrin αvβ3 promotes tumor progression and metastasis in a diverse array of human carcinomas, and may be integral to epithelial stem/progenitor cell behavior. Here we reveal a critical role for αvβ3 in adult mammary stem cells (MaSCs) during pregnancy. While αvβ3 is a luminal progenitor marker in the virgin mammary gland, we noted a dramatic increase in αvβ3 expression in the MaSC pool at mid-pregnancy associated with enhanced repopulating potential. Similar to pregnancy, we noted that TGFβ, and not RANKL, was sufficient to drive αvβ3 expression enhancing MaSC activity. Accordingly, mice lacking β3 or expressing a signaling deficient form of this receptor showed defective mammary gland morphogenesis during pregnancy associated with decreased MaSC clonogenicity, expansion and outgrowth potential. Surprisingly, these mice displayed normal development of the virgin gland with no effect on luminal progenitors. These findings support a role for αvβ3 as a critical determinant of the MaSC state during pregnancy and suggest a related role for this receptor in regulating stem-like behavior in human breast cancers.
Citation Format: Jay Desgrosellier, Jacqueline Lesperance, Laetitia Seguin, Sanford Shattil, David Cheresh. Integrin αvβ3 drives the mammary stem cell state during pregnancy. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr A036.
Abstract A039: The role of long noncoding RNAs in epithelial to mesenchymal transition and cancer stem cells
Authors: Herschkowitz Jason I. , Coarfa Cristian , Prat Aleix , Toneff Michael J. , Hoadley Katherine A. , Dinger Marcel E. , Mattick John S. , Mani Sendurai A. , Perou Charles M. , Rosen Jeffrey M. 
Published: May 2015

Abstract
The claudin-low subtype is generally triple (ER, PR, HER2) negative and there are currently no targeted agents directed at them. These tumors express low levels of tight and adherens junction genes including claudin 3 and E-cadherin, and high levels of markers associated with epithelial-mesenchymal transition (EMT) including Snail, Twist, and Zeb1/2. Claudin-low tumors are also enriched in signatures derived from human tumor-initiating cells and a sorted population enriched for human mammary stem cells. miRNAs are differentially expressed in claudin-low tumors including low expression of the miR-200 family - regulators of EMT and stemness. MiR-200 overexpression in claudin-low cell lines causes them to lose this classification and to adopt an expression profile of another subtype. While there has been considerable emphasis on miRNAs, our knowledge is still lacking about the role of long noncoding RNAs (lncRNAs) that comprise the majority of the mammalian transcriptome. Here, we have examined the expression profiles of &gt;17,000 lncRNAs in a large set of breast tumors. Like mRNAs and miRNAs, lncRNAs differ dramatically in expression across subtypes and can be used for classification. LncRNAs that are differentially regulated in cell lines induced to undergo EMT are associated with claudin-low tumors and we have identified some of these lncRNAs as potential regulators of the EMT/CSC phenotype. We have begun to study the subcellular localization and potential function of a couple of these candidate lncRNAs using RNA FISH and siRNA knockdown respectively. These results suggest major roles for noncoding RNAs in claudin-low breast tumors and in the regulation of breast cancer stem cells.
Citation Format: Jason I. Herschkowitz, Cristian Coarfa, Aleix Prat, Michael J. Toneff, Katherine A. Hoadley, Marcel E. Dinger, John S. Mattick, Sendurai A. Mani, Charles M. Perou, Jeffrey M. Rosen. The role of long noncoding RNAs in epithelial to mesenchymal transition and cancer stem cells. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr A039.
Abstract A055: A novel cell growth control pathway repressed by the oncogene TBX2 in breast cancer cells
Authors: D'Costa Zenobia Carmel , Higgins Catherine A. , Williams Richard , Mullan Paul B. 
Published: May 2015

Abstract
Purpose: To identify a therapeutic target downstream of TBX2 which may be used to treat this aggressive subset of breast cancers
T-box 2 (TBX2) is a transcriptional repressor known to drive breast cancer proliferation. It is known to switch off a number of key cell cycle regulatory molecules such as p21WAF1 and p14ARF. A breast cancer Disease Specific Array identified &gt;700 potential TBX2 regulated genes. We have validated one particular target, Cystatin 6 (CST6), to be consistently repressed by TBX2 in a panel of breast cancer cell lines. CST6 is a putative breast tumor suppressor and we observe that exogenous expression of CST6 resulted in cell death of breast cancer cells but not in non-tumorigenic breast cell lines. Mechanistically, we show that TBX2 transcriptionally represses CST6 in an EGR-1 dependent manner rather than through direct CST6 promoter binding.
CST6 is a cysteine protease inhibitor known to repress several members of Clan CA (papain family) and Legumain (LGMN, an asparginyl endopeptidase from the Clan CD family). LGMN has previously been reported to be highly expressed in breast cancers compared to normal breast tissue. Through a range of genomic approaches we showed that LGMN was responsible for driving the proliferation of breast cancer cell lines. Consequently, knockdown of LGMN by siRNA resulted in cell death in breast cancer cell lines overexpressing TBX2. We are in the process of generating small molecule inhibitors against LGMN. Preliminary studies have shown promise with growth inhibitory effects on breast cancer cells but not in non-tumorigenic MCF10A breast cells. LGMN inhibitors may be useful for targeted treatment for breast and other tumors types showing high levels of LGMN expression where it is known to play roles in control of ECM remodeling/turnover, tumor growth and in the development of metastases. LGMN is also known to process and activate a number of downstream oncogenic proteins and we show that one of these proteins, matrix metalloproteinase-2 (MMP2), may contribute to the aggressive traits of LGMN-expressing breast cancer cells.
Conclusions: We have determined a proliferative/invasive pathway employed by breast cancer cells and identified a protein downstream ‘LGMN’ which may be therapeutically targeted to prevent oncogenesis in a subset of breast cancers.
Citation Format: Zenobia Carmel D'Costa, Catherine A. Higgins, Richard Williams, Paul B. Mullan. A novel cell growth control pathway repressed by the oncogene TBX2 in breast cancer cells. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr A055.
Abstract A077: Post-transcriptional regulation of CXCR4 by the tristetraprolin/HuR axis in breast cancer
Authors: Al-Souhibani Norah A. , Al-Ghamidi Maha , Al-Ahmadi Wijdan , Khabar. Khalid SA 
Published: May 2015

Abstract
Chemokine receptors can direct tumors to distant organs and tissues along a gradient of their respective ligands. One such chemokine receptor is CXCR4 which has been implicated in breast cancer metastasis, notably to the lung, bone, and lymph nodes, where its chemokine ligand, CXCL12, is highly expressed. Expression of the receptor or its ligand is associated with a poor prognosis. Here, we report that aberrations in the post-transcriptional regulation of the CXCR4/CXCL12 signaling pathway play a pivotal role in the metastatic phenotype of breast cancer cells.
We show, utilizing 3′UTR reporter assays, that CXCR4 3′UTR contains an AU-rich element that confers instability to its mRNA and presents it as a prospective target for RNA binding proteins. Indeed, immunoprecipitation of TTP- and HuR-bound mRNA and RNA shift revealed CXCR4 mRNA is a novel target of both proteins suggesting post-transcriptional regulation of the chemokine receptor. We demonstrate correlation between the aberrant TTP/HuR axis and increased CXCR4 expression and metastasis in Tumor Cancer Genome Atlas (TCGA) breast cancer patient data. Furthermore, real-time PCR and western blotting techniques showed that CXCR4 mRNA and protein levels were significantly higher in the invasive breast cancer cell line MDA-MB-231 compared to the non-invasive MCF7 or normal cell lines. Using MDA-MB-231 cells as a model of invasive breast cancer, we attempted to normalize the aberrant TTP/HuR axis by a miR-29a inhibitor which led to de-suppression of TTP expression. This triggered increased instability of CXCR4 mRNA, a down regulation of CXCR4 expression, and a subsequent reduction in the migratory potential of MDA-MB-231 cells. The anti-invasive and anti-migratory effect was similarly obtained by knockdown of HuR and CXCR4. Further regulation of CXCR4 by TTP and HuR was substantiated by mRNA decay assays and 3′UTR reporter experiments. Our findings indicate that CXCR4 is a novel target of post-transcriptional regulation by the RNA binding proteins TTP and HuR and that restoration of a normal balance between TTP and HuR may offer a novel therapeutic approach in the control of metastatic breast cancer.
Citation Format: Norah A. Al-Souhibani, Maha Al-Ghamidi, Wijdan Al-Ahmadi, Khalid SA Khabar. Post-transcriptional regulation of CXCR4 by the tristetraprolin/HuR axis in breast cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr A077.
Abstract A082: Study of the effects of localized collagen manipulation on the behavior of breast cancer cells
Authors: Clark Ashley N. , Williams James , Padgen Michael , Keely Patricia , Castracane James 
Published: May 2015

Abstract
The tumor microenvironment is complex and heterogeneous, comprised of the extracellular matrix, various cell types, blood vessels, and soluble factors. Multiple interactions occur between tumor cells and their environment which affect cellular behavior and the composition of the tumor microenvironment. Changes to the composition of collagen within the tumor microenvironment have been linked to an increased risk of developing breast carcinoma and an increased invasiveness of breast cancer cells. The goal of this study is to understand how selected, well-controlled manipulations of the collagen composition alter the behavior of an invasive human breast cancer cell line, MDA-MB-231. A BioMEMS device will be loaded with molecules that alter collagen and inserted into a 3-D gel containing MDA-MB-231 cells, to establish a localized gradient of these molecules. The compositional changes include increased collagen concentration through stimulating cellular deposition of collagen, increased collagen crosslinking and inhibition of a collagen cross-linker produced by tumor cells. Confocal reflectance microscopy, atomic force microscopy, and environmental scanning electron microscopy are utilized to characterize the changes induced and the rates at which the changes occur. Changes in gene expression are investigated to determine the pathways each of the collagen manipulations induce which result in the observed changes to cellular behavior. The observed alterations in cellular phenotype resulting from these collagen changes will help to better understand what degree of changes occur within breast carcinoma resulting in cancer progression.
Citation Format: Ashley N. Clark, James Williams, Michael Padgen, Patricia Keely, James Castracane. Study of the effects of localized collagen manipulation on the behavior of breast cancer cells. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr A082.
Abstract A085: miR-222/221 in aggressive breast cancer
Authors: Leva Gianpiero Di , Piovan Claudia , Cheung Douglas , Briskin Daniel , Kumar Arpan , Nuovo Gerard , Fassan Matteo , Coppola Vincenzo , Garofalo Michela , Croce Carlo 
Published: May 2015

Abstract
MicroRNAs (miRNAs) are small non coding RNAs that regulate gene expression at post-transcriptional level through translational inhibition and/or degradation of mRNA target genes. Recent evidence points to a widespread role for miRNAs in the initiation and progression of tumorigenesis in a plethora of tissues including the mammary gland. Aberrant miRNA expression profiles have been described in breast cancer specimens compared to normal tissues, discriminating breast tumors with different clinico-biological phenotypes. In our previous publications, we have demonstrated that miR-222/221 cluster is highly expressed in aggressive breast cancer and high levels of miR-222/221 may confer a proliferation advantage to cancer cells and resistance to therapeutic agents by repressing several genes such as ERα;, CDKN1B, BIM, FOXO3, CAV1, PTEN. To demonstrate the in vivo role of miR-222/221 cluster in breast cancer initiation and progression, we have genetically deleted miR-222/221 gene in the MMTV-PyVT mouse model that develops multifocal mammary adenocarcinoma and lung metastatic lesions in 80% of the population. The tumor latency and multiplicity were assessed and none of these parameters were significantly affected by miR-222/221 ablation. Interestingly, lack of miR-222/221 impairs the development of lung metastasis with a reduction of the metastatic load of the lung. Moreover, metastases arising from miR-222/221 deficient cells present a greater cytoarchitectural similarity and a reduced rate of mitosis and apoptosis. We also show that loss of miR-222/221 modulates the transcriptome and miRNA expression profiles of mouse breast tumors and cancer cells, stimulating a stronger estrogen receptor alpha transcriptional network and a suppression of the cancer stem cells population.
Citation Format: Gianpiero Di Leva, Claudia Piovan, Douglas Cheung, Daniel Briskin, Arpan Kumar, Gerard Nuovo, Matteo Fassan, Vincenzo Coppola, Michela Garofalo, Carlo Croce. miR-222/221 in aggressive breast cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr A085.
Abstract A087: Angiogenin (ANG) localized at the leading edges of breast cancer cells regulates plasmin formation by plasminogen activation complex (PAC) and cell migration
Authors: Dutta Sujoy , Bandyopadhyay Chirosree , Wilson Lydia , Warshall Case , Bottero Virginie , Johnson Karen E. , Chandran Bala 
Published: May 2015

Abstract
Angiogenin (ANG), a 14-kDa pro-angiogenic protein, had been shown to play a role in cell migration and tumor invasion processes, which involve proteolytic cleavage of plasminogen to generate plasmin. However, the mechanism by which ANG regulates plasmin formation and cell migration was not known. Our studies detected elevated levels of secreted ANG and cell surface-bound ANG in highly invasive metastatic breast cancer cells. By immunofluorescence and immunoprecipitation analysis, ANG was detected at leading edges of the cell surfaces where it colocalized and interacted with members of the plasminogen activation complex (PAC) such as Annexin A2 (A2), Calpactin (S100A10) and Urokinase plasminogen receptor (uPAR). Analysis of lipid raft (LR) and non-lipid raft (NLR) regions of the cell membranes showed the predominance of ANG, A2 and S100A10 in the LR regions. In contrast, uPAR was detected only in the NLR fractions, suggesting that ANG interacts with uPAR at junctions of LR and NLR regions. ANG knockdown in T47D and MDA-MB-231 breast cancer cell lines did not affect the cellular expression of A2, S100A10 and uPAR but decreased cell migration and plasmin formation. Neutralization of ANG with monoclonal antibodies similarly decreased the migration of MDA-MB-231 cells. In the presence of ANG on cell surfaces, uPAR was observed to interact with UPA, which is known to be necessary for proteolytic cleavage of plasminogen by UPA to form plasmin. However, in the absence of ANG, uPAR interacted exclusively with PAI, which is known to inhibit plasmin formation by blocking UPA mediated proteolytic cleavage of plasminogen. Assessment of phosphorylation states of cellular FAK and Src kinases under these conditions further showed that both FAK and Src are dephosphorylated in the absence of ANG. Taken together, our results identified a novel regulatory role of ANG as a bridging protein that facilitates the interaction of uPAR with UPA, which leads to plasmin formation and cell migration necessary for tumor invasion and metastasis of breast cancer cells. These studies also suggest that ANG could serve as a bio-marker for identifying the leading edges of metastatic breast cancer cells and targeting ANG could be a novel method to block breast cancer invasiveness.
Citation Format: Sujoy Dutta, Chirosree Bandyopadhyay, Lydia Wilson, Case Warshall, Virginie Bottero, Karen E. Johnson, Bala Chandran. Angiogenin (ANG) localized at the leading edges of breast cancer cells regulates plasmin formation by plasminogen activation complex (PAC) and cell migration. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr A087.
Abstract A097: Inhibition of the Na+/H+ exchanger (NHE1) increases susceptibility to paclitaxel in invasive breast cancer cells
Authors: Amith Schammim Ray , Wilkinson Jodi Marie , Fliegel Larry 
Published: May 2015

Abstract
The pH gradient in normal cells is tightly controlled by the activity of various pH regulatory membrane proteins including the Na+/H+ exchanger, NHE1. NHE1 becomes constitutively active in a neoplastic milieu, dysregulating pH homeostasis and altering the survival, differentiation, and proliferation of cells, thus causing them to become tumorigenic. In breast cancer cells, cytoplasmic alkalinization as a result of NHE1 hyper-activity results in an acidic tumor microenvironment that facilitates aggressive cellular proliferation, migration, and invasion leading to tumor metastasis. The pathophysiological role of NHE1 in tumor progression with regards to ion flux is well known, however, the manipulation of pH in and around tumor cells has only recently been considered as a strategy in augmenting cancer therapy. We studied the effect of NHE1 inhibitors EMD87580 ((2-methyl-4,5-di-(methylsulfonyl)-benzoyl)-guanidine) and HMA (5-(N, N-hexamethylene)-amiloride), either alone or in combination with paclitaxel (Taxol), on NHE1 exchanger activity, cell viability, proliferation, migration, and invasive potential, in a highly invasive breast cancer cell line MDA MB 231. We found that cells treated with EMD or HMA in combination with paclitaxel at low doses (0.1nM to 1nM), were significantly more susceptible to cell death than cells treated with paclitaxel or inhibitors alone. While no discernible differences between treatments were observed in cell proliferation rates, a significant reduction in the rate of migration and invasion was observed in cells treated with paclitaxel and either EMD or HMA. To highlight the importance of NHE1 function, we also generated an MDA-MB-231NHE1- knockout cell line for comparison with the wild-type cells that endogenously express NHE1. The NHE1 knockout cell line showed no demonstrable Na+/H+ exchange activity, and much lower rates of proliferation, migration and invasion compared to wild-type cells. Our results demonstrate, for the first time, that inhibition of NHE1 potentially increases the susceptibility of invasive breast cancer cells to paclitaxel-mediated cell death at doses much lower than the established IC50 of paclitaxel in MDA MB 231 cells. Since pH regulation appears to play an integral role in the switch from a normal to a neoplastic microenvironment, these data lend further credence to the importance of NHE1 as a potential target in breast cancer chemotherapy.
Supported by the Canadian Breast Cancer Foundation.
Citation Format: Schammim Ray Amith, Jodi Marie Wilkinson, Larry Fliegel. Inhibition of the Na+/H+ exchanger (NHE1) increases susceptibility to paclitaxel in invasive breast cancer cells. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr A097.
Abstract A098: Contribution of macrophages to FGFR-dependent breast cancer
Authors: Brady Nicholas J. , Farooqui Mariya , Bohrer Laura , Schwertfeger Kaylee 
Published: May 2015

Abstract
Genomic profiling studies have demonstrated that a number of potentially targetable pathways are capable of contributing to breast cancer, including the fibroblast growth factor receptor (FGFR) pathway. Our studies focus on understanding the mechanisms through which FGFR1 activation in tumor cells leads to pro-tumorigenic changes in the microenvironment. Specifically, using an in an in vivo model of fibroblast growth factor receptor 1 (FGFR1)-induced mammary tumorigenesis, we have found that following FGFR1 activation in mammary epithelial cells, macrophages are recruited to the hyperplastic regions where they are required for angiogenesis and epithelial cell proliferation. To identify the factors that contribute to the pro-tumorigenic microenvironment, we have developed two- and three-dimensional co-culture in vitro models to mimic what is observed in vivo. Using these in vitro models, we have identified that soluble factors derived from FGFR1-activated epithelial cells lead to the upregulation of target genes in macrophages that promote tumor formation, invasion, and migration. Findings from the in vitro studies are further assessed using a mouse mammary tumor model utilizing orthotopic transplants into immunocompetent mice. These model systems will help us identify novel regulators of mammary tumorigenesis and provide new insight into the mechanisms by which macrophages promote tumor formation.
Citation Format: Nicholas J. Brady, Mariya Farooqui, Laura Bohrer, Kaylee Schwertfeger. Contribution of macrophages to FGFR-dependent breast cancer. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Breast Cancer Research: Genetics, Biology, and Clinical Applications; Oct 3-6, 2013; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2013;11(10 Suppl):Abstract nr A098.