bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A014: A clinically relevant prognostic mRNA signature for triple-negative breast cancer developed from the patient-derived xenograft model
Authors: Moon Hyeong-Gon , Oh Keunhee , Lee Dong-Sup , Han Wonshik , Noh Dong-Young
Published: May 2015

Triple-negative breast cancer (TNBC) is a unique subtype of breast cancer which lacks effective targeted agent and has a relatively worse prognosis when compared to other subtypes. Identifying a molecular characteristic associated with poor prognosis and classifying TNBC patients accordingly can help the clinicians to provide tailored therapeutic approach.

Using a patient-derive xenograft model which use patients' primary breast cancer tissues xenotransplanted into the immunodeficient mice, the xenograft take rates of various molecular subtypes of breast cancer were examined. Also, the mRNA expression profile associated with the xenograft tumor formation was investigated in 13 TNBC patients. The genes showing differential expression according to the xenograft tumor formation were tested in an independent publicly available TNBC mRNA expression datasets to assess the prognostic importance.

Among the 81 primary breast cancer tissues used for the xenotransplantation experiments, 19 (23.4%) developed xenograft tumors. Cancer tissues from TNBC patients were more likely to develop xenograft tumors (48%) when compared to other subtypes. The TNBC-derived xenograft tumors showed rapid and exponential tumor growth when compared to luminal type cancers. The genetic characteristics of the primary tumor were maintained after serial xenotransplantation in the immunodeficient mice suggesting the validity of the patient-derived xenograft model for translational research. In 13 TNBC tumors, the mRNA expression profiles were obtained by using microarray chip experiment to identify a genetic characteristic associated with the xenograft tumor formation. Gene involved in immune-reponse, cell migration, angiogenesis and vascular formation were significantly up or downregulated according to the xenograft tumor formation. Among the 13 TNBC patients, the distant metastases were developed only in tumors which formed xenograft tumors. The individual genes showing differential expression, as well as the global expression profile of xenograft tumor formation, was associated with the distant metastasis risk in an independent TNBC mRNA expression datasets.

In conclusion, the present study has identified a set of genes that carry prognostic implication in TNBC patients by using the patient-derived xenograft models.

Citation Format: Hyeong-Gon Moon, Keunhee Oh, Dong-Sup Lee, Wonshik Han, Dong-Young Noh. A clinically relevant prognostic mRNA signature for triple-negative breast cancer developed from the patient-derived xenograft model. [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 A014.
Abstract A037: YB-1 transforms mammary epithelial cells through chromatin remodeling leading to the development of basal-like breast cancer
Authors: Davies Alastair H. , Reipas Kristen M. , Firmino Natalie , Stratford Anna L. , Berns Rachel , Fotovati Abbas , Pambid Mary , Hu Kaiji , Maxwell Chris , Mills Gordon B. , Dunn Sandra E.
Published: May 2015

There is growing evidence that cancer-initiation could result from epigenetic changes. Y-box binding protein-1 (YB-1) is a transcription/translation factor that promotes the formation of tumors in transgenic mice; however, the early molecular events leading up to this are not understood. To address this in a human model system, YB-1 was expressed in mammary epithelial cells under a tetracycline-inducible promoter. The induction of YB-1 drove the development of ductal carcinoma in situ (DCIS) in vitro. Underlying these events, YB-1 induced p300, promoted its nuclear localization, and heightened histone acetylation leading to chromatin relaxation. Subsequently, chromatin relaxation allowed YB-1 to bind to the BMI1 promoter based on chromatin immunoprecipitation. The induction of BMI1 engaged the PRC1 complex as histone H2A was ubiquitinated and p16INK4a was silenced. These events manifested functionally in sustained self-renewal that occurred in a BMI1 dependent manner. Conversely, p300 inhibition with anacardic acid prevented YB-1 from binding to the BMI1 promoter and thereby subverted self-renewal. Accordingly, transient expression of YB-1 in the normal mammary 184hTERT and MCF10A cells had the same effect on chromatin remodeling and self-renewal. Despite these early changes, full malignant transformation was not achieved until RSK2 was expressed leading to elevated hTERT activity. The YB-1/RSK2/hTERT expressing cells formed DCIS and invasive ductal carcinoma in mice that were molecularly subtyped as basal-like breast cancer (BLBC). We conclude that YB-1 cooperates with p300 to allow BMI1 to over-ride p16INK4a enabling self-renewal and the formation of tumors.

Citation Format: Alastair H. Davies, Kristen M. Reipas, Natalie Firmino, Anna L. Stratford, Rachel Berns, Abbas Fotovati, Mary Pambid, Kaiji Hu, Chris Maxwell, Gordon B. Mills, Sandra E. Dunn. YB-1 transforms mammary epithelial cells through chromatin remodeling leading to the development of basal-like 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 A037.
Abstract A042: Role of mTOR as a transcriptional regulator in breast cancer
Authors: Alalem Mohamed , Ray Alpana , Ray Bimal
Published: May 2015

There is substantial evidence that metformin, an anti-diabetic biguanide, correlates with improved breast cancer response to chemotherapy. The exact mechanism of metformin's beneficial effect in breast cancer is yet to be fully understood. Metformin inhibits a serine/ threonine kinase called mammalian target of rapamycin (mTOR), which is a central regulator of various intracellular and extracellular stimuli. mTOR transduces signaling from growth factors, such as insulin, to stimulate mRNA translation. Insulin activates mTOR through PI3K-Akt-mediated phosphorylation and consequent activation of protein machinery to promote protein synthesis. Increased protein synthesis in cancer cells contributes to cancer progression. Improved response of breast cancer cells response to chemotherapy following metformin treatment suggests inhibition of mTOR in breast cancer regression. Being a serine / threonine kinase, mTOR may also have a potential role in the regulation of gene transcription via modulating the activity of some transcription factors, particularly, those involved in cell proliferation and differentiation. Kruppel-like factor 4 (KLF-4) is one such transcription factor which is involved in epithelial cells differentiation and proliferation and it is potentially regulated by mTOR. The objective of this study, therefore, was to investigate whether mTOR regulates gene expression by modulating the activity of KLF-4 in breast cancer.

Our hypothesis was that mTOR inhibition by metformin results in the upregulation of KLF-4, which functions as a tumor suppressor. Elucidation of the molecular basis of metformin's effect on KLF-4 could provide the basis for adjuvant therapy in breast cancer.

Western blot (WB) studies indicate overexpression of mTOR in some breast cancer cells compared to normal breast epithelial cells. In contrast, WB and Immunohistochemistry studies indicate overexpression of KLF-4 in normal breast cells compared to cancer breast cells. Metformin treatment, with and without insulin, resulted in decreased mTOR level with a concomitant increase in KLF-4 level in breast cancer cells. These results suggest a role of metformin in mediating the inverse relationship between mTOR and KLF-4 in breast cancer.

Citation Format: Mohamed Alalem, Alpana Ray, Bimal Ray. Role of mTOR as a transcriptional regulator 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 A042.
Abstract A043: Targeting defective DNA repair for the prevention of BRCA1-mutated breast cancer
Authors: Alli Elizabeth , Solow-Cordero Dave
Published: May 2015

Carriers of germline mutations in the Breast Cancer Susceptibility Gene 1 (BRCA1) have an increased risk for developing breast cancer. Unfortunately, BRCA1-mutated cancers are not amenable to current chemoprevention options, often associate with an aggressive clinical course, and thus, are in need of an effective prevention strategy. We previously found that BRCA1 plays a role in DNA base-excision repair (BER) of oxidative DNA damage (ODD), and that BRCA1-mutated breast cancers exhibit a compromised ability for BER of ODD. Given that excessive ODD leads to tumorigenesis, we hypothesized that repair of ODD may be enhanced to prevent tumorigenesis of BRCA1-mutated breast cancer. To test this hypothesis, we first identified drugs that enhance BER of ODD in the presence of mutant BRCA1. To do so, we conducted a high-throughput chemical screen using small molecules with known pharmacological activity. Two of these compounds, which have been approved for other clinical indications, enhanced BER in mutant BRCA1 but not wild-type BRCA1 cell lines. These molecules also decreased basal levels of ODD as determined by flow cytometry using a FITC-conjugated 8oxoG-binding protein and decreased H2O2-induced ODD as determined by the alkaline comet assay modified for detection of oxidized lesions. Second, we analyzed certain effects of these drugs that would negatively affect their ability to function as chemoprevention agents. Both drugs showed no cytotoxicity at concentrations that enhanced BER of ODD as seen by the MTT assay and Hoechst-staining for live cells. Both drugs directly activated BER, rather than indirectly as a result of induction of DNA damage, as evidenced by the alkaline comet assay for DNA strand breaks. Finally, at least one of these drugs decreased in vitro tumorigenesis of BRCA1-mutant and isogenic BRCA1-deficient cells using the soft agar colony formation assay and simultaneously had no significant effect on cell viability as determined by the trypan blue exclusion assay. Taken together, these data suggest a novel strategy for the targeted chemoprevention of BRCA1-associated breast cancers.

Citation Format: Elizabeth Alli, Dave Solow-Cordero. Targeting defective DNA repair for the prevention of BRCA1-mutated 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 A043.
Abstract A045: Cadherin-11, a common therapeutic target in poor prognosis malignancies and rheumatoid arthritis
Authors: Assefnia Shahin , Dakshanamurthy Sivanesan , Auvil Jaime M. Guidry , Hampel Constanze , Anastasiadis Panos , Kallakury Bhaskar , Uren Aykut , Foley David W. , Brown Milton , Shapiro Lawrence , Brenner Michael , Haigh David , Byers Stephen W.
Published: May 2015

Rational: Poor prognosis epithelial-derived cancers often exhibit morphologic and molecular changes characteristic of an epithelial to mesenchymal transition (EMT). EMT markers are predominantly found in tumors with a basal-like phenotype. Increased expression of the mesenchymal cadherins N-cadherin and/or Cadherin-11 (CDH11) and decreased E-cadherin, have been associated with both EMT and tumor progression. Importantly, CDH11 is a therapeutic target in rheumatoid arthritis (RA), an inflammatory disease with properties often compared with cancer. As CDH11 antibody based therapeutics are in clinical trials for RA and we recently showed that the arthritis drug celecoxib has the structural potential to bind CDH11, there is a strong possibility that, if CDH11can be shown to drive malignant progression rather than simply be associated with it, therapeutic options may be rapidly developed.

Results: We show that CDH11 is increased early in breast cancer and ductal carcinoma in-situ. CDH11 knockdown and antibodies effective in RA slowed the growth of basal-like breast tumors. CDH11 attenuation decreased proliferation and colony formation of breast, glioblastoma and prostate cancer cells. The arthritis drug celecoxib, which has characteristics consistent with CDH11 binding, an analogue without COX-2 inhibitory activity and other molecules that target CDH11, preferentially affect CDH11 positive cancer cells.

Conclusion: Our work demonstrates that cadherin-11 is important for malignant progression, is a therapeutic target in several aggressive tumors and introduces an antibody, novel small molecules and an approved arthritis drug that inhibit its function with potential for rapid clinical translation.

Citation Format: Shahin Assefnia, Sivanesan Dakshanamurthy, Jaime M. Guidry Auvil, Constanze Hampel, Panos Anastasiadis, Bhaskar Kallakury, Aykut Uren, David W. Foley, Milton Brown, Lawrence Shapiro, Michael Brenner, David Haigh, Stephen W. Byers. Cadherin-11, a common therapeutic target in poor prognosis malignancies and rheumatoid arthritis. [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 A045.
Abstract A047: Targeting androgen receptor decreases proliferation of triple-negative breast cancer
Authors: Barton Valerie , D'Amato Nicholas , Richer Jennifer
Published: May 2015

Recent studies demonstrate that the androgen receptor (AR) is expressed in up to a third of triple negative breast cancer (TNBC) and define a subtype of TNBC with a “luminal AR” gene signature. We hypothesized that AR+TNBC are dependent on AR for growth and that inhibiting AR activity by preventing nuclear localization and DNA binding will decrease proliferation and tumor burden in preclinical models of breast cancer. Indeed, knock down of AR expression using a lentiviral shRNA significantly reduced proliferation in cell line models of TNBC compared to cells transduced with a non-targeting control (2-fold reduction, p<0.001). Propidium iodide cell cycle analysis demonstrated that TNBC cells with reduced AR expression had a 22% increase in the percentage of cells in S-phase (p<0.001). In TNBC cells that exhibit androgen-stimulated growth, reduced AR expression inhibited response to ligand. Enzalutamide, an AR inhibitor, inhibited ligand mediated nuclear translocation of AR as assessed by nuclear cytosolic fractionation and significantly decreased baseline proliferation of TNBC in vitro (p<0.001). In MDA453 xenografts, enzalutamide significantly decreased tumor volume and weight by up to 85% and increased apoptosis as measured by cleaved caspase-3 by 60% compared to mice that received DHT alone. In addition, a 50% reduction in nuclear AR was observed in the tumors of mice treated with enzalutamide. Thus AR may play an important role in a subset of TNBC and presents an opportunity for targeted therapy.

Citation Format: Valerie Barton, Nicholas D'Amato, Jennifer Richer. Targeting androgen receptor decreases proliferation of triple-negative 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 A047.
Abstract A053: ErbB3 downregulation enhances luminal breast tumor response to antiestrogens
Authors: Morrison Meghan M. , Stanford Jamie , Young Christian , Vaught David , Williams Andrew , williams michelle , Perou Chuck M. , Arteaga Carlos L. , Cook Rebecca S.
Published: May 2015

HER3/ErbB3 is required in luminal mammary epithelial cells (MECs). Given that breast cancer phenotypes may reflect biological traits of the MECs from which they originate, we tested the hypothesis that HER3/ErbB3 drives luminal breast cancer growth. We found higher ERBB3 expression and frequent ERBB3 gene copy gains in clinical Luminal A/B breast cancers over other molecular subtypes. ErbB3 increased growth of luminal breast cancer cells, while ErbB3 targeting using U3-1287, a fully-human monoclonal anti-ErbB3 antibody, decreased three-dimensional colony growth, increased apoptosis, and decreased tumor growth in vivo. In response to the anti-endocrine fulvestrant, ErbB3 expression increased in clinical breast tumors, as did phosphatidylinositol 3-kinase (PI3K)/mTOR signaling. However, ErbB3 targeting with U3-1287 blocked compensatory PI3K/mTOR signaling in fulvestrant-treated tumor cells, transcriptional responses to fulvestrant, tumor cell survival and tumor growth. U3-1287 produced these effects in tumor cells with and without genetic PI3K pathway aberrations (PIK3CAH1047R, PIK3CAE545K, PTEN loss). Although fulvestrant increased phosphorylation of all ErbB family RTKs and insulin-like growth factor-1 receptor, phospho-RTK upregulation was not seen in tumors treated with U3-1287 and fulvestrant. Therefore, luminal breast cancer cells utilize ErbB3 for growth, survival, and to limit response to fulvestrant, thus defining a novel role for ErbB3 in breast cancer.

Citation Format: Meghan M. Morrison, Jamie Stanford, Christian Young, David Vaught, Andrew Williams, michelle williams, Chuck M. Perou, Carlos L. Arteaga, Rebecca S. Cook. ErbB3 downregulation enhances luminal breast tumor response to antiestrogens. [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 A053.
Abstract A057: Therapeutic potential of genistein via targeting the microRNA miR-155 in breast cancer
Authors: Parra Columba de la , Castillo-Pichardo Linette , Cubano Luis A. , Calin George A. , Dharmawardhane Suranganie
Published: May 2015

We previously reported that dietary genistein significantly inhibits mammary tumor growth and metastasis of estrogen receptor (ER) (-) MDA-MB-435 metastatic cancer cells in immunocompromised mice. The purpose of the present study is to investigate the molecular mechanisms of genistein in ER (-) breast cancer cells. We report that at low physiologically relevant concentrations, genistein significantly inhibits cell growth and induces apoptosis in MDA-MB-435 and Hs578t breast cancer cells. To investigate the mechanism by which genistein regulates cancer cell viability, a panel of microRNAs (miRNAs) were tested for differential expression in response to genistein treatment. We found that miR-155, a designated oncomiR in breast cancer, is significantly downregulated by genistein in MDA-MB-435 and Hs578t cells. Concomitantly, pro-apoptotic and anti-cell proliferative miR-155 targets FOXO3, PTEN, casein kinase (CK1alpha), and p27 are upregulated by genistein. Moreover, the CK1alpha target beta catenin is downregulated in the MDA-MB-435 cells, thus further contributing to the anticancer effects of genistein by inhibiting wnt signaling. Stable ectopic expression of miR-155 in MDA-MB-435 and Hs578t cells decreases the inhibitory effect of genistein on cell viability, and abrogates the effect of genistein on apoptosis and expression of pro-apoptotic proteins. Therefore, genistein acts as a potential anti breast cancer therapeutic via downregulation of miR-155, a critical suppressor of apoptosis. This study was sponsored by United States Army/BCRP W81XWH-11-1-0199 (to CDP), NIH/NIGMS SC3GM084824 (to SD), NIH/NIGMS G12RR035051 (to UPR MSC), and NIH/NIGMS G12RR003035 and Title V PPOHA US Department of Education #P031M105050 (to UCC).

Citation Format: Columba de la Parra, Linette Castillo-Pichardo, Luis A. Cubano, George A. Calin, Suranganie Dharmawardhane. Therapeutic potential of genistein via targeting the microRNA miR-155 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 A057.
Abstract A068: Targeting Akt reactivation following mTOR inhibition in breast cancer treatment
Authors: Alayev Anya , Snyder Rose B. , Holz Marina K.
Published: May 2015

Breast cancer is the second leading cause of cancer related deaths in women and up to 60% of diagnosed cases are estrogen receptor (ER)-positive. ER-positive status is associated with a poor prognosis. While ER-positive cancers could be targeted with endocrine therapy, such as aromatase inhibitors, resistance often develops. Therefore, there is a need to better understand molecular contributions of other signaling pathways with the goal of treating patients with personalized combination therapies.

The mechanistic target of rapamycin complex 1 (mTORC1) regulates cell cycle progression and proliferation and is a target of a naturally occurring inhibitor rapamycin. The 40S ribosomal S6 Kinase 1 (S6K1) is one of the best characterized downstream targets of mTORC1. The mTORC1/S6K1 pathway is often hyperactivated in breast cancer, promoting cell growth and proliferation. S6K1 is encoded by the RPS6KB1 gene, located on the 17q23 chromosomal region. While this region is amplified in several types of cancer, multi-copy amplicons are found specifically in breast cancer, underscoring the importance of S6K1 in this disease. Importantly, there is a direct link between the mTORC1/S6K1 and ER signaling pathways. S6K1 directly phosphorylates and activates ER, promoting ligand-independent ER activation and endocrine resistance. Based on this data, current FDA approved treatment of advaced ER-positive breast cancer combines mTORC1 inhibitors with endocrine therapy.

Some of the concerns that arise with the use of mTORC1 inhibitors (rapamycin analogs or rapalogs) is that they promote induction of autophagy and relieve the negative feedback signaling to Akt effected by S6K1, which promotes oncogenic Akt signaling, survival, and further stimulates mTORC1/S6K1 signaling, which may contribute to acquired drug resistance and patient relapse.

Our research focuses on identifying agents that could be combined with mTORC1 inhibitors to block S6K1 while maintaining negative feedback signaling to Akt. Our results show that such combination treatment does in fact prevent rapamycin-induced upregulation of Akt while maintaining inhibition of the S6K1 signaling pathway, as assayed by analysis of S6K1 targets PDCD4, eIF4B and S6. Moreover, the combination treatment inhibits autophagy and promotes apoptosis. Thus, the combined inhibition of S6K1 and Akt may prevent or reverse drug resistance in breast cancer.

Citation Format: Anya Alayev, Rose B. Snyder, Marina K. Holz. Targeting Akt reactivation following mTOR inhibition in breast cancer treatment. [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 A068.
Abstract A094: The influence of pro-metastatic protein NEDD9 expression in supporting distant breast cancer metastasis
Authors: Ice Ryan J. , Mahavadi Sricharan A. , Pugacheva Elena N.
Published: May 2015

Although advances in treating early stage breast cancer have increased the overall survival rate, once the disease has metastasized treatment options become severely limited. Neural precursor cell expressed developmentally downregulated 9, NEDD9, is a pro-metastatic protein known to play a role during invasion and is increased in many tumor types including ductal breast carcinomas. The purpose of our study is to understand how NEDD9 contributes to the survival of metastatic disease and to establish via therapeutically relevant means the impact of reducing NEDD9 in metastatic breast cancer. Utilizing breast tumor xenograft models and in situ Zymography we were able to conclude that the reduction of NEDD9 led to a decrease in matrix metalloproteinase activity in the tumor cells in the primary site and distant lung metastasis thus reducing the number of invading cells. Additionally our study shows, via fluorescent immunohistochemistry analysis of lung metastasis, that by reducing the levels of NEDD9 in vivo the levels of active caspase 3 increased, along with decreasing Ki67 and phosphorylated Akt levels. These changes led to decreased proliferation and survival and increased cell death at distant metastatic sites and dramatically reduced number and size of lung metastasis. Finally, we have demonstrated that the application of NEDD9 Vivo-morpholinos is a valid method for targeting NEDD9 in a clinically relevant setting to reduce the levels of NEDD9 for treatment of metastatic breast cancer. Taken together our data suggests that not only does NEDD9 play a role in primary tumor invasion but is necessary for sustaining metastatic disease and can be reduced in a clinically viable manner resulting in less metastasis.

Citation Format: Ryan J. Ice, Sricharan A. Mahavadi, Elena N. Pugacheva. The influence of pro-metastatic protein NEDD9 expression in supporting distant breast cancer metastasis. [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 A094.
Abstract A095: The microenvironmental basis of AXL regulation
Authors: Jokela Tiina , Stampfer Martha , Lorens James , LaBarge Mark
Published: May 2015

AXL tyrosine kinase expression is a strong negative prognostic factor for survival of human breast cancer, and its expression is significant in metastases. Breast cancer metastasis is promoted by epithelial-mesenchymal transition (EMT), where epithelial cells lose their cell-to-cell contacts and polarity, resulting in transformation to a fibroblastic migratory phenotype. During EMT process, AXL is highly expressed, and knockdown of AXL completely prevents the invasion of breast cancer cells via EMT-based mechanisms. EMT is promoted by specific transcription factors like slug or oncogenes like Ras, but interestingly, without extracellular signaling feedback, cells will lose the EMT state and invasion capability.

In this study we characterize extracellular stimuli that stabilize AXL expression and the EMT-phenotype in human mammary epithelial cells. In Vitro studies were implemented with HMEC-derived cell lines, which have traceable origins and were derived through defined immortalization steps. Mammary epithelial cells were induced into an EMT phenotype by Slug-overexpression and exposure to different microenvironments. AXL and other EMT markers were monitored in each cell passage. Results have shown that with Slug-expressing cells lose the EMT phenotype after a few cell passages. When Slug induced HMECs were cultured on Micro Environment microArrays (MEArray), specific microenvironments were revealed that increased and stabilized AXL expression. Our results show that microenvironmental signals are essential to induce and maintain the EMT phenotype.

Citation Format: Tiina Jokela, Martha Stampfer, James Lorens, Mark LaBarge. The microenvironmental basis of AXL regulation. [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 A095.
Abstract A109: A signal peptide as a putative tool against MMTV-associated breast cancers
Authors: Braitbard Ori , Bar-Sinai Allan , Roniger Maayan , Rajchman Dana , Hochman Nira , Hochman Jacob
Published: May 2015

Mouse Mammary Tumor Virus (MMTV) causes mammary carcinoma and lymphoma in mice. An increasing body of evidence from different laboratories suggests an association between MMTV and up to 38% of human breast cancers. This seems related to severity of the disease and geographical location. Signal peptides are N-terminal extensions of nascent secretory and membrane proteins (typically including 15-25 amino acid residues). They mediate translocation across, or insertion into the membrane of the endoplasmic reticulum (ER). The signal peptide of Mouse Mammary Tumor Virus (MMTV) envelop precursor (named MMTV-14 or p14 for short), in addition to being unusually long (98 a.a) demonstrates some unique characteristics: 1) It localizes to nucleoli; 2) It functions as a nuclear export factor for intron-containing viral transcripts; 3) It can function in a pro-oncogenic or anti-oncogenic capacity depending on its phosphorylation by the kinases CK2 (at serine 65) or PKC (at serine 18), respectively. We report that, in addition to its nucleolar localization, p14 is expressed on the cell surface of murine lymphomas and mammary carcinomas that harbor MMTV, as well as on the surface of MCF-7 human breast cancer cells ectopically expressing p14. Cell surface expression allows p14 to play the role of a tumor associated antigen. Indeed, priming and boosting of mice with recombinant p14, using different adjuvants, induces specific anti-p14 antibodies, as well as immunizes these mice against malignant tumor cells that harbor MMTV. This immunity is adoptively transferred to naïve mice. Thus, MMTV-p14 is a multi-faceted signal peptide with immune modulating characteristics that can be used for developing both preventive and therapeutic approaches towards MMTV-associated breast cancers.

Supported in part by a Kamin grant from the Office of the Chief Scientist.

Citation Format: Ori Braitbard, Allan Bar-Sinai, Maayan Roniger, Dana Rajchman, Nira Hochman, Jacob Hochman. A signal peptide as a putative tool against MMTV-associated breast cancers. [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 A109.
Abstract A114: Differential gene expressions in breast cancer epithelia of African American and European American women: Health disparity at the molecular level
Authors: Bagasra Omar , Howard Khirston , Johnson Leslie
Published: May 2015

Mortality rates from breast cancer (BC) remain higher in African-American (AA) women despite a lower incidence when compared to European American (EA) women. Multiple factors including differences in access to health care, disparate utilization of screening tools as well as biologic factors are being explored as causative agents. We are addressing this concern by studying the expressions of BC signaling pathway genes in paired BC cell lines from AA and EA patients. The total mRNAs from the primary cell lines from both ethnic groups were analyzed by utilizing gene array for breast cancer signaling pathways (SABioSciences). The array analyses showed that there were nine genes which were commonly regulated in both races including: BAD, BAG1, CCNE1, IL6R, IL6ST, ITGB4, MAP2K7, PLAU and PTGS2. Overall, estrogen receptor (BAG1, CYP19A1), inflammation (C3) or metastasis and cell integrity (COL6A1, ID2) or apoptosis (BAD) genes were represented. However, there were numerous genes that were differentially expressed between the two racial groups. In AA, the following genes were down regulated: CDKN2A, CLDN7, CTNNB1, CTSD, EGFR, ESR1, HMGB1, KRT18, STC2 and TP53. One of the most significantly genes was ESR1, the estrogen receptor 1 gene which was down regulated in the AA as compared to EA and may play an important role in AA BC development. There were eight genes that were differentially expressed in EA. These include: CCD1, FOSL1, GSN, IL2RA, IL6, ITGA6, NFYB and SLC7A. Some of these differentially expressed genes may play a protective role in EA. These findings may help us uncover that the molecular basis of high BC mortality in AA and may help in the development of biomarkers for the early diagnosis of BC.

Citation Format: Omar Bagasra, Khirston Howard, Leslie Johnson. Differential gene expressions in breast cancer epithelia of African American and European American women: Health disparity at the molecular level. [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 A114.
Abstract B024: Comprehensive biomarker profiling of matched primary and metastatic estrogen receptor positive breast cancers
Authors: Spoerke Jill M. , Schleifman Erica B. , Desai Rupal , Xiao Yuanyuan , Wong Cheryl , Abbas Ilma , O'Brien Carol , Patel Rajesh , Sumiyoshi Teiko , Fu Ling , Tam Rachel , Koeppen Hartmut , Wilson Timothy , Raja Rajiv , Hampton Garret M. , Lackner Mark R.
Published: May 2015

Patients with newly diagnosed, early stage estrogen receptor positive (ER+) breast cancer often show disease free survival in excess of five years following surgery and systemic adjuvant therapy. As such, an important question is whether diagnostic tumor tissue from the primary lesion offers an accurate molecular portrait of the cancer post recurrence and thus may be used for predictive diagnostic purposes for patients with relapsed, metastatic disease. To address this question, we performed detailed biomarker analyses on matched, asynchronous primary and metastatic tumors from 77 patients with ER+ breast cancer.

The class I phosphatidylinositol 3' kinase (PI3K) is thought to be an important driver in ER+ breast cancer and has been linked to acquired resistance to hormonal therapy. We thus examined whether mutations in PIK3CA and loss of PTEN showed differences in primary and metastatic samples. We also sought to look more broadly at markers reflective of proliferation, molecular subtype, and key receptors and signaling pathways. To accomplish this, we developed an analysis platform using the Fluidigm BioMark™ microfluidics system to measure the relative expression of 90 breast cancer related genes in formalin-fixed paraffin-embedded (FFPE) tissue.

Application of this panel of assays to matched tumor pairs showed a very high concordance between primary and metastatic tissue, with generally few changes in mutation status, proliferative markers, or gene expression between matched samples. Thus, archival primary tumor tissue may still provide an accurate portrait of biomarker status in patients with disease recurrence.

Citation Format: Jill M. Spoerke, Erica B. Schleifman, Rupal Desai, Yuanyuan Xiao, Cheryl Wong, Ilma Abbas, Carol O'Brien, Rajesh Patel, Teiko Sumiyoshi, Ling Fu, Rachel Tam, Hartmut Koeppen, Timothy Wilson, Rajiv Raja, Garret M. Hampton, Mark R. Lackner. Comprehensive biomarker profiling of matched primary and metastatic estrogen receptor positive breast cancers. [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 B024.
Abstract B064: Anti-phospho-estrogen receptor alpha (Ser305), clone 124.9.4, is a potential clinical antibody marker for tamoxifen-resistant breast cancer
Authors: Speckmann Wayne , Brockett Robert , Yang Chun , Solache Alejandra
Published: May 2015

Resistance to tamoxifen is one of the major challenges in breast cancer treatment. Different mechanisms related to tamoxifen sensitivity have been widely investigated, including the phosphorylation of ERα. It has been shown experimentally that phosphorylation of estrogen receptor alpha at serine 305 (ERαS305-P) by protein kinase A (PKA) leads to an activation of ERα and to transcription of ERα-responsive gene after tamoxifen treatment [EMBO J 26:3534-3544][EMBO J 21:5437-5447], leading to tamoxifen resistance. More recently, clinical studies also show that ERαS305-P may be a good biomarker to identify patients unlikely to respond to tamoxifen [J Pathol 217:372-379][Breast Cancer Res Treat 125(1):1-12]. Here we developed and validated a rabbit monoclonal anti-phospho-estrogen receptor alpha (Ser305) antibody, EMD Millipore 05-922R., with immunohistochemistry (IHC) validation on different breast cancer patient samples and other non-breast cancer tissue micro array (TMA) samples.

Citation Format: Wayne Speckmann, Robert Brockett, Chun Yang, Alejandra Solache. Anti-phospho-estrogen receptor alpha (Ser305), clone 124.9.4, is a potential clinical antibody marker for tamoxifen-resistant 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 B064.
Abstract B067: Taxonomy of breast cancer based on normal cell phenotype and ontology
Authors: Thakkar Ankita , Santagata Sandro , Ergonul Ayse , Wang Bin , Woo Terri , Hu Rong , Harrell J. Chuck , McNamara George , Schwede Matthew , Culhane Aedin C. , Kindelberger David , Rodig Scott , Richardson Andrea , Schnitt Stuart J. , Tamimi Rulla M. , Ince Tan A.
Published: May 2015

The classification of lymphoma and leukemia is successfully done by using normal cell types as a reference point which is one of the many reasons that better therapies are available for their treatment. In case of breast cancer, clinically it is classified as Estrogen Receptor positive, Human Epidermal Growth Factor Receptor 2 (Her2) positive and triple negative breast cancer while in the research settings, it has been classified by mRNA expression profiling but these classification systems are still evolving. Our laboratory attempted to classify breast cancer by examining the expression of different keratin isoforms and Hormone Receptors (HR) studied through immunostaining in 36 normal breast samples and later in 1731 breast tumors from the Nurses' Health Study (NHS) cohort with a patient follow up extending beyond 25 years. Among the various receptors tested, three of these receptors: Androgen Receptor, Estrogen Receptor and Vitamin D Receptor were capable of identifying four major subgroups being designated as HR0-3, depending on the number of hormone receptors present. More importantly, radically different survival outcomes were observed between these HR sub-groups through Kaplan Meier curve analysis; which highlights their usefulness as vital biological markers as wells as targets for breast cancer treatment. Furthermore, the characterization of these HR was carried out in 20 different breast cancer cell lines and the combination of different receptor modulators alone or in combination was attempted with better anti-proliferative effects being observed in the combinatorial group than either treatment alone. Thus, our new classification not only re-classifies breast cancer but also gives insight on how patients could be treated through targeting hormone receptors.

Citation Format: Ankita Thakkar, Sandro Santagata, Ayse Ergonul, Bin Wang, Terri Woo, Rong Hu, J. Chuck Harrell, George McNamara, Matthew Schwede, Aedin C. Culhane, David Kindelberger, Scott Rodig, Andrea Richardson, Stuart J. Schnitt, Rulla M. Tamimi, Tan A. Ince. Taxonomy of breast cancer based on normal cell phenotype and ontology. [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 B067.
Abstract B077: Breast tumor kinase (Brk/PTK6) is a mediator of hypoxia/HIF-associated breast cancer progression
Authors: Seagroves Tiffany N. , Lange Carol A.
Published: May 2015

Triple negative (basal type) breast cancers (TNBC) are aggressive and difficult to treat relative to luminal type breast cancers. These tumors frequently express abundant Met receptors and are enriched for transcriptional targets regulated by hypoxia inducible factor 1-alpha (HIF-1α), a principal mediator of cell stress that independently predicts cancer relapse and increased risk of metastasis. We recently showed that breast tumor kinase (Brk/PTK6) is a critical downstream effector of Met signaling. Herein, we examined the regulation of Brk by HIFs in TNBC cell lines and mouse models. Brk mRNA and protein levels are strongly upregulated by hypoxia, low glucose and reactive oxygen species in vitro. HIF knockdown demonstrated that BRK expression is dependent upon both HIF-1α; and HIF-2α; and chromatin-immunoprecipitation (ChIP) assays revealed that Brk is a direct transcriptional target of HIF-1α/α. Notably, knockdown of HIF-1α/2α in MDA-MB-231 cells significantly diminished xenograft growth; Brk re-expression reversed this effect. Finally, we crossed WAP-Brk (FVB) transgenic mice into the METmut knock-in (FVB) model. Expression of the Brk transgene augmented METmut-induced mammary tumor formation and metastasis. Surprisingly, mouse mammary tumors that arose in either METmut or WAP-Brk X METmut mice expressed abundant Sik, the mouse homolog of Brk, which conferred markedly increased tumor formation and decreased survival. These results identify HIF-1α/2α as novel regulators of Brk expression and suggest that Brk is a key mediator of hypoxia-induced breast cancer progression. Targeting Brk expression or activity may provide an effective means to block the progression of aggressive breast cancers (supported by NIH R01 CA107547 (C.A.L.) and NIH R01 CA138488 (T.N. S.).

Citation Format: Tiffany N. Seagroves, Carol A. Lange. Breast tumor kinase (Brk/PTK6) is a mediator of hypoxia/HIF-associated breast cancer progression. [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 B077.
Abstract B089: The suppression of ERa activity promotes the mitochondrial deficient CD133hi/Notch3hi/ERalow cancer stem cell phenotype via autocrine IL6 in luminal breast cancer
Authors: Sansone Pasquale , Bonafe Massimiliano , Ceccarelli Claudio , Berishaj Marjan , Bromberg Jacqueline
Published: May 2015

The inhibition of ERa pathway (hormonal therapy -HT-) is the most effective therapeutic strategy for metastatic luminal breast cancer. However, the efficacy of HT is time-limited, suggesting that metastatic disease will eventually employ an ERa-independent biochemistry. Here we demonstrated that CD133hi/CD44low tumor initiating cells arise following ERa lack of function via oxidative phosphorylation (OXPHOS) dysfunction. These cells display a remarkable migrating and metastatic phenotype, which associate with the downregulation of ERa and the increased expression of Notch3. Chronic lack of ERa activity by tamoxifen generates CD133hi/Notch3hi/ERalow via the up-regulation of tumor-derived IL6. We then showed that IL6 confers resistance to ERa lack of function by up-regulating glycolysis/OXPHOS. Finally, higher expression of CD133, Notch3 and IL6 identifies ERalow luminal breast cancers endowed with metastatic and self-renewal potentials. In conclusion, our data demonstrate that oxidative phosphorylation dysfunction and autocrine IL6 are key molecular triggers of intra-tumor heterogeneity and tumor initiating capabilities in luminal breast cancer refractory to anti ERa target therapy.

Citation Format: Pasquale Sansone, Massimiliano Bonafe, Claudio Ceccarelli, Marjan Berishaj, Jacqueline Bromberg. The suppression of ERa activity promotes the mitochondrial deficient CD133hi/Notch3hi/ERalow cancer stem cell phenotype via autocrine IL6 in luminal 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 B089.
Abstract IA12: Mammary epithelial subtypes and their implications for breast cancer
Authors: Rios Anne , Fu Naiyang , Pal Bhupinder , Lindeman Geoffrey , Visvader Jane
Published: May 2015

To understand relationships between breast tissue and ‘cells of origin’ of breast cancer, it is important to dissect the normal mammary epithelial hierarchy. Discrete populations of mouse and human mammary epithelial cells can be isolated on the basis of cell surface markers and subsets that are highly enriched for mammary stem (MaSC), luminal progenitor and mature luminal cells have been identified. These are functionally analogous across species and have highly conserved transcriptomes.

Lineage tracing is an important approach for assessing the stem cell hierarchy as it allows stem and progenitor cell fate to be studied in situ in the context of development, tissue maintenance and disease. Indeed, recent studies in the mammary gland have described unipotent stem cells that appear to control the different stages of development. Here we have combined lineage tracing with a novel three-dimensional (3D) imaging strategy to explore the relative contributions of stem and progenitor cells in the post-natal mammary gland. Newly generated transgenic strains harboring lineage-specific gene regulatory regions are also being used to direct the expression of specific mammary oncogenes to discrete epithelial cell types to gain insight into cells of origin of breast cancer.

Citation Format: Anne Rios, Naiyang Fu, Bhupinder Pal, Geoffrey Lindeman, Jane Visvader. Mammary epithelial subtypes and their implications for 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 IA12.
Abstract IA26: Stroma-targeted immunotherapy
Authors: Gottschalk Stephen , Karkala Sunitha , Williams LaTerrica , Song Xiao-Tong
Published: May 2015

The tumor-associated stroma has garnered increasing attention for its role in initiating and sustaining tumor growth. Occupying up to 90% of the tumor mass, the stroma is composed of heterogeneous cell types, of which cancer associated fibroblasts (CAFs) are preponderant. CAFs support tumor progression directly through paracrine secretion of cytokines, growth factors etc., and indirectly by mediating resistance to chemo-, radio- and immunotherapy. Additionally, therapies directed to cancer cells often fail to eradicate CAFs, which can reinstate a tumorigenic milieu and favor recurrence.

CAFs express markers that distinguish them from their normal counterparts, allowing them to be selectively targeted. One such marker is fibroblast activation protein-α (FAP), a type II dipeptidyl peptidase originally isolated from CAFs in human sarcomas. FAP expression was subsequently detected on CAFs in over 90% of common epithelial cancers including colorectal, breast, pancreatic, skin and lung tumors, and is often correlated with poor prognosis. Selective ablation of FAP-positive stromal cells in a transgenic mouse model permitted immunological control of tumor growth, indicating their significant immunosuppressive function in the microenvironment. Targeting FAP-positive CAFs therefore presents an attractive strategy to augment current cancer-targeted therapies. While ‘unarmed’ FAP-specific monoclonal antibodies had no antitumor activity in humans, several groups have demonstrated the benefit of FAP-targeted vaccines or FAP-specific immunotoxins in preclinical animal models. In this presentation we will summarize current efforts to target FAP-positive CAFs with vaccines and adoptive T-cell therapy in preclinical animal models. In addition, we will review other potential immunotherapeutic targets within the tumor stroma.

Citation Format: Stephen Gottschalk, Sunitha Karkala, LaTerrica Williams, Xiao-Tong Song. Stroma-targeted immunotherapy. [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 IA26.