bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract P6-04-23: Targeting of endocrine therapy resistance through combined mTOR and histone deacetylase inhibition
Authors: Ordentlich P , Flechsig S , Hoffmann J 
Published: August 2014

Abstract
Background: Primary and acquired resistance to endocrine therapy in advanced breast cancer presents a significant barrier to maximizing the clinical effectiveness of these agents. Preclinical data has demonstrated that up-regulation and/or constitutive activation of estrogen independent growth signaling pathways drive resistance to aromatase inhibitors and that targeting of these pathways is an effective strategy to overcoming the resistance. We recently reported in a randomized, placebo controlled phase 2 study that entinostat (ENT), an oral class 1 selective HDAC inhibitor, combined with exemestane extended PFS and OS in postmenopausal women with ER+ positive breast cancer that had progressed on a prior nonsteroidal aromatase inhibitor. Likewise, everolimus (EVE), a mTORi, combined with exemestane or tamoxifen (TAM) also significantly extended PFS in a similar patient population. In order to determine the potential benefit of combining ENT with EVE plus hormone therapy we have piloted a series of xenograft studies in primary human tumor models of TAM sensitivity and resistance.
Methods: Athymic nude mice bearing xenografts of tissue derived directly from patient tumors (MaCa4049 – TAM sensitive; MaCa3366/TAM – partially resistant to TAM) were treated with A) vehicle B) 2 mg/kg EVE C) 2 mg/kg EVE + 10 mg/kg TAM D) 15 mg/kg ENT E) 2mg/kg EVE + 10mg/kg TAM + 15 mg/kg ENT. Tumor samples taken at the end of the study were cryoconserved for analysis of gene and protein expression and protein phosphorylation.
Results: Growth of MaCa4049 tumors was inhibited in all treatment groups relative to vehicle in two independent studies conducted in this tumor model. Groups B, C and D demonstrated a similar level of activity while maximal inhibition was observed in Group E (combination of EVE + ENT + TAM). All treatments were generally well tolerated with weight loss similar in groups C and E. Treatment of MaCa3366/TAM tumors resulted in similar levels of tumor growth inhibition in groups B, C and E which were all highly effective in suppressing tumor growth in this model. As EVE alone was highly effective as a single agent in the MaCa3366/TAM model the contribution of ENT will be assessed through molecular analysis of tumors upon study completion. Efficacy results and analysis of tumor samples from completed studies will be presented to provide insight into mechanism of action for the triple combination.
Conclusions: Preclinical data demonstrating enhanced activity of entinostat combined with everolimus and hormone therapy provides the rationale for clinical investigation of this novel therapeutic approach to targeting hormone therapy resistance.
Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-04-23.
Abstract P6-04-24: Overexpression of protein kinase C alpha differentially activates transcription factors in T47D breast cancer cells in the presence of 17β-estradiol both in the 2D and 3D environments.
Authors: Pham TND , Asztalos S , Weiss MS , Shea LD , Tonetti DA 
Published: August 2014

Abstract
Background: Our lab has previously shown that overexpression of protein kinase C alpha (PKCα) results in a hormone independent, tamoxifen resistant phenotype in the T47D:A18 breast cancer cell line. Moreover, 17β-estradiol (E2) inhibits colony formation of T47D/PKCα in 3D Matrigel and tumor growth in vivo but not in the 2D environment (Zhang et al, Mol. Cancer Res, 2009). Differential transcriptional activation may account for the phenotypic changes observed in T47D/PKCα cells. In this study, we sought to identify transcription factors (TF) differentially activated in T47D:A18/neo versus T47D:A18/PKCα grown in 3D Matrigel in the presence and absence of E2, and compare these TFs with those activated in the 2D environment using a high-throughput screening (HTS) technology.
Methods: A system for rapid, non-invasive, large scale, dynamic quantification of TF activity was developed (Weiss et al, PLoS ONE, 2010). Reporter constructs were created containing a TF binding site that preceeds a basal promoter to produce firefly luciferase (Fluc) using a lentiviral backbone. The control construct contained only the basal promoter and was used for normalization. T47D/PKCα and T47D/neo cells were infected with lentiviral reporter constructs. Cells were seeded either on top of Matrigel or without Matrigel in 384 well plates in E2-free media. After 3 days, cells were treated with either E2 (10–9M) or vehicle (0.1% ethanol). Fluc activity was assessed by bioluminescence imaging at 24, 48 and 72 hours following treatment using Xenogen IVIS Spectrum imaging system.
Results: Initial findings showed differential transcriptional activities between the parental T47D/neo and T47D/PKCα cell lines at the basal level (without E2 treatment) in the 3D environment. Specifically, TFs involved in tumorigenesis (such as ETS1, STAT5) or the EMT process (such as SNAI1) were more highly activated in T47D/PKCα cells. Furthermore, E2 has a modulating effect on the activities of TFs in the two cell lines over time; observed both in the 2D and 3D environments. In particular, some TFs, such as Oct4, ETS1, and Stat5; were modulated (either induced or suppressed) by E2 only in T47D/PKCα cells.
Conclusion: These findings suggest that overexpression of PKCα alters TF activity in T47D breast cancer cells both basally and in response to E2. This HTS technology allowed us to reveal the dynamic regulation of TF activation in PKCα overexpressing T47D breast cancer cells. We are now beginning to understand the mechanism whereby PKCα may mediate differential response to E2 dependent on the microenvironment. This HTS approach is likely to lead to the identification of new therapeutic targets.
Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-04-24.
Abstract P6-04-27: EBAG9 immunoreactivity is a potential prognostic factor for poor outcome of breast cancer patients with adjuvant tamoxifen therapy
Authors: Shigekawa T , Ijichi N , Ikeda K , Miyazaki T , Horie-Inoue K , Shimizu C , Saji S , Aogi K , Tsuda H , Osaki A , Saeki T , Inoue S 
Published: August 2014

Abstract
Estrogen receptor-binding fragment associated gene 9 (EBAG9) is a primary estrogen responsive gene originally cloned from MCF-7 human breast carcinoma cells. Upregulation of EBAG9 expression has been observed in several malignant tumors such as advanced breast cancers, indicating that EBAG9 may contribute to tumor progression. In the present study, the immunohistochemical analyses of EBAG9 were performed using the specimens from breast cancer patients treated with tamoxifen as adjuvant therapy. To investigate the association between EBAG9 expression and the therapeutic effect of tamoxifen in breast cancer, we used adjuvant tamoxifen-treated breast cancer patient tissues from 3 institutions. The study was approved by the institutional review board. Patients with distant metastases within 5 years after surgery followed by tamoxifen treatment were defined as relapse cases, whereas those without distant metastases were defined as relapse-free cases. The immunoreactivity of EBAG9 was predominantly detected in the cytoplasm of breast cancer cells. Notably, EBAG9 immunoreactivity level was substantially elevated in the breast cancer samples from the relapse patients, and the positive immunoreactivity of EBAG9 was correlated with poor prognosis of the patients with adjuvant therapy. These results suggest that EBAG9 expression in tumor regions is associated with unfavorable prognosis of patients with adjuvant tamoxifen therapy and EBAG9 immunoreactivity can serve as a biomarker for adjuvant tamoxifen efficacy.
Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-04-27.
Abstract P6-05-03: Targeted inhibition of recurrent PIK3CA mutations synergizes with bicalutamide in AR-expressing triple negative breast cancer
Authors: Lehmann BD , Bauer JA , Schafer JM , Tang L , Pendleton CS , Sanders ME , Pietenpol JA 
Published: August 2014

Abstract
Triple negative breast cancers (TNBC) are generally more aggressive than other types of breast cancer, with higher rates of relapse in the early stage and decreased overall survival in the metastatic setting. TNBC has been particularly difficult to treat given that the biology of the disease is not well understood, and until recently, molecular targets for therapeutic intervention have remained elusive. Lacking HER2 amplification as well as estrogen and progesterone receptors, TNBC appears to be a heterogeneous collection of biologically diverse cancers, which likely contributes to variable clinical outcomes for patients suffering from this disease. Using gene expression analyses, we recently identified six distinct molecular TNBC subtypes with unique biologies that include two basal-like (BL1 and BL2), an immunomodulatory (IM), a mesenchymal (M), a mesenchymal stem-like (MSL), and a luminal androgen receptor (LAR) subtype. We demonstrated that the growth of LAR cell line models was dependent on AR signaling, as siRNA-mediated AR knockdown or pharmacological inhibition by bicalutamide greatly diminished viability. In addition we previously demonstrated that LAR cell lines are highly sensitive to the PI3K/mTOR inhibitor NVP-BEZ235. Interestingly, we observed that all AR-positive TNBC cell lines examined contain PIK3CA mutations (H1047R) suggesting selection for deregulation of the PI3K pathways during evolution of AR expressing breast cancers. Further investigation of a panel of AR-positive TNBC tumors showed that PIK3CA kinase mutations are a frequent event in this TNBC subtype (69.2% vs. 26.9%) and not just an artifact of the LAR cell line models. We show that PI3K pathway activation plays a role in resistance to AR antagonists, as there are elevated levels of activated AKT in residual tumors after bicalutamide treatment of xenograft tumors. Furthermore, we demonstrate that genetic/pharmacological targeting of AR synergizes with PI3K/mTOR inhibition in both two- and three-dimensional cell culture models. Moreover, the combination of bicalutamide with PI3K/mTOR inhibitors GDC0980 or NVP-BEZ235 decreased tumor volume in mouse xenograft studies. Our preclinical data provide the rationale for pre-selecting AR-positive TNBC patients for future clinical trials evaluating the combination of AR antagonists with PI3K/mTOR inhibitors.
Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-05-03.
Abstract P6-05-04: Expression of the Androgen Receptor in triple negative tumors and its modulation by receptor tyrosine kinases and downstream pathways
Authors: Cuenca D , Montero JC , Morales JC , Prat A , Pandiella A , Ocana A 
Published: August 2014

Abstract
Background: Androgen receptor (AR) plays a central role in some tumor types like prostate cancer. Its expression and function in breast cancer is relatively unknown. Studies have linked tyrosine kinase (TK) receptors and their intracellular signaling pathways with AR status. In the present work we study the presence of AR in breast cancer human samples and how TKs can control its expression.
Methods: Tumor samples from patients were used to assess the expression of AR by western-blot. Membrane and intracellular kinases were evaluated using phosphoprotein arrays. Cell lines representative of all breast cancer subtypes were used to assess the expression of the AR and other signaling proteins using western-blot and phosphoprotein arrays. Proliferation studies with several kinase inhibitors were measured by MTT assays. We also interrogated publicly available gene expression microarray data sets with annotated clinical-pathological data.
Results: Across all the intrinsic subtypes of breast cancer, the expression of AR gene was found highly expressed in HER2-enriched and Luminal tumors and lowly expressed in Basal-like and/or triple-negative (TN) tumors. In TN tumors, PDGFRβ and EGFR were found highly activated, together with AKT and Erk1/2. A positive correlation was observed between activation of EGFR and PDGFRβ and the expression of AR. In vitro, AR protein expression varied across cell lines and was found more expressed in MCF7 (Luminal) and HS578T (TN), BT549 (TN), HCC70 (TN) and no expressed in HBL100 (TN) and MDA-MB231 (TN). Administration of the antiandrogen bicalutamide produced an anti-proliferative effect that was increased by association of an Erk1/2 inhibitor. Inhibition of the PI3K-mTOR pathway in BT549 and HS578T reduced the expression of AR but did not augment the action of bicalutamide. In TN tumors, AR gene and protein was found more expressed in older compared to younger patients.
Conclusions: In breast cancer, AR is expressed and is controlled by receptor TKs through the PI3K-mTOR pathway. An increased anti-proliferative effect is observed with the combination of bicalutamide and Erk1/2 inhibitors. AR expression correlates with age at diagnosis.
Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-05-04.
Abstract P6-05-06: Serum estradiol levels in postmenopausal ER+/PR- breast cancer are lower than those in postmenopausal ER+/PR+
Authors: Yamamoto Y , Ibusuki M , Goto H , Murakami K , Iwase H 
Published: August 2014

Abstract
(Background) Activation of growth factor receptor (GFR) signaling is related with ER+/PR- breast cancer (BC). Proportion of ER+/PR- phenotype in ER+ BC in postmenopausal patients is higher than that in premenopausal. However, this phenomenon cannot be explained by only GFR signaling activation. We hypothesized that ER+/PR- phenotype in postmenopausal patients has at least two subtypes, one is related with activation of GFR signaling and the other is related with suppression of PR expression due to low estrogenic stimulation.
(Purpose) The aim of this study is to clarify out hypothesis.
(Patients and methods) We measured serum E2 levels with radioimmuno assay (range of E2 levels: 1.3 to 50 pg/ml) in 154 postmenopausal ER+ BC patients. Cut-off levels of ER and PR were used 10% or more expression in tumor cells. We analyzed the correlation between serum levels of E2 and clinicopathological factors including PR expression. We also examined the relationship between HER2 expression levels and ki67 labeling index in ER+/PR- BC. In addition, we analysed the difference in ki67 LI between in premenopausal patients (n = 65) and in postmenopausal patients.
(Results) Median serum levels of E2 in ER+/PR+ phenotype (6.7 pg/ml) were significantly higher than in ER+/PR- phenotype (4.5 pg/ml)(p = 0.036). Serum levels of E2 was positively associated with body mass index (p = 0.01). However, there was no significant difference between serum E2 levels and other clinicopathological factors including tumor size, nodal status, nuclear grade, levels of ER expression and ki67 LI. In ER+/PR- phenotype, ki67 LI were varied (Median: 7.5%, range: 0.5 to 85%). Ki67 LI in Postmenopausal patients with ER+/PR- phenotype was significantly lower than that in premenopausal patients with ER+/PR- phenotype (p = 0.0022). Expression levels of HER2 was positively associated with ki67 LI(p = 0.002).
(Conclusions) ER+/PR- cancer in postmenopausal patients may have two types of phenotype. One is highly proliferative phenotype that is stimulated with GFR signaling. The other is low proliferative one that PR expression is suppressed by without sufficient estrogen supply. Serum levels of E2 might affect development of ER+ BC in postmenopausal women, especially in case of no activation of GFR signaling.
Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-05-06.
Abstract P6-05-08: Significant heterogeneity in ERalpha and PR receptor status in different distant breast cancer metastases of the same patient
Authors: Hoefnagel LDC , van der Groep P , Broers JE , van der Wall E , van Diest PJ 
Published: August 2014

Abstract
Purpose: Receptor conversion for estrogen receptor alpha (ERα), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) in single distant breast cancer metastases has been described before. However, most patients develop multiple metastases. Heterogeneity in receptor status between different metastases of the same patient has not been studied, probably since such material is very rare. The consequence of such heterogeneity would mean that as many metastases as possible need to be biopsied to re-assess receptor status.
We therefore aimed to study heterogeneity of receptor status between different distant metastases of the same patient in a relatively large group by re-staining all primary tumors and metastases with current optimal immunohistochemical methods on full sections.
Material and methods: Formalin fixed paraffin embedded tissue of primary breast carcinomas and corresponding multiple (≥2) distant metastases from 38 female patients were collected from several pathology departments in The Netherlands and stained for ERα, PR and HER2 by IHC. We evaluated the heterogeneity of receptor status between the metastases and the correlation with the primary tumor.
Results: In the 4 cases that showed ER conversion, 2 (50%) showed heterogeneity in receptor expression between different metastases of the same patient. Of the 17 cases that showed PR conversion, 12 cases (71%) showed heterogeneity in expression between metastases. There were no changes in the receptor profile of primary breast cancer to their metastases for HER2 in this group.
Conclusion: In a significant number of metastatic breast cancer patients, there is heterogeneity in ER and PR receptor status between different breast cancer metastases of the same patient. This implies that as many metastases as possible need to be biopsied to re-assess receptor status and set the optimal indication for hormonal therapy in these patients. Alternatively, non-invasive assessment of the receptor status by molecular imaging may be an easier future way to assess receptor status of all metastatic lesions.
Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-05-08.
Abstract P6-05-12: Lack of Frequent Estrogen Receptor Mutation in Primary Breast Tumors
Authors: Oesterreich S , Kitchens C , Gavin P , Wu C-C , Riehle K , Coarfa C , Edwards D , Schiff R , Milosavljevic A , Lee A 
Published: August 2014

Abstract
The estrogen receptor alpha (ESR1) is a critical driver of breast tumorigenesis, and as such has been a target for therapy for many years. Early reports using Sanger sequencing and conformational assays reported that there were little if any mutations in ER-positive tumors, although a few somatic mutations have recently been described in tumors and cell lines. We set out to validate the authenticity of these reported somatic mutations by performing analysis of ER DNA sequence variants (DSVs) in 66 ER+ breast tumors, and 39 breast cancer cell lines. We utilized a combined approach of target capture sequencing of ESR1, and subsequent testing for novel and previously identified DSVs using an orthogonal mass spectrometry based sequencing approach. A DNA capture approach was designed to capture all exons, flanking splice sites, and the 3′ UTR of ESR1. DNA was captured and sequenced using SOLiD.
Using stringency with a cut-off with at least 2 variant reads, variants in at least 20% of the reads, and requiring evidence for the variants in both strands, we identified 4 previously reported SNPs (rs2077647; rs46432; rs1801132; rs2228480), and two previously reported somatic mutations H6Y and N532Y. We developed mass-spectrometry assays, including controls, for these DSVs, and in addition, we included 10 DSVs which had previously been reported as somatic mutations in breast (and other) cancer. Applying mass-spec based analysis to breast tumors and cell lines, we were able to confirm previously reported SNPs, and one previously reported mutations (H6Y). This mutation was found in one breast tumor and one cell line. None of the other reported somatic mutations could be confirmed in tumors or cell lines. Functional assays on the ESR1H6Y DSV failed to identify differences to wildtype receptor. The lack of a phenotype, and the infrequent occurrence of this DSV do not support a major driver role for ESR1H6Y.
This analysis suggests that ESR1 mutations are a rare event in ER+ primary breast cancer.
Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-05-12.
Abstract P6-06-01: Lobular involution reduces breast cancer risk through downregulation of invasive and proliferative cellular processes
Authors: Radisky DC , Visscher DW , Stallings-Mann ML , Frost MH , Allers TM , Degnim AC , Hartmann LC 
Published: August 2014

Abstract
Background: Age-related lobular involution (LI) is a physiological process, usually accelerated with menopause, in which the epithelial tissue of the breast gradually regresses. Our previous analysis of a cohort of more than 14,000 women who had a benign breast biopsy at the Mayo Clinic revealed that women who had undergone LI were at significantly reduced risk of subsequent breast cancer development. In our studies of postmenopausal women specifically, we found that more than 40% had not completed the process of LI, and that the increased breast cancer incidence in older women was strongly associated with incomplete LI. We sought to determine the potential protective mechanistic effects of lobular involution.
Methods: We generated primary human mammary epithelial cell lines (HMECs) from breast biopsies of women who showed no LI (N = 6), partial LI (N = 7), or complete LI (N = 6). These cell lines were analyzed for proliferation in culture and profiled for genomic signatures using Affymetrix gene arrays. We also analyzed RNA isolated from a cohort of archived formalin-fixed, paraffin-embedded (FFPE) benign breast biopsy samples from postmenopausal women who had either completed the process of LI (N = 4) or who had not initiated LI (N = 8) for genomic signatures using Whole-Genome DASL Assays.
Results: We found that LI was associated with decreased cellular proliferation and inhibition of processes associated with tumor development and progression. Specifically, we found that HMECs derived from benign breast biopsies in which LI was not evident showed increased proliferation and elevated expression of Twist (p = 0.002), a transcription factor associated with epithelial-mesenchymal transition (EMT) and breast cancer development. We are assessing differentially expressed genes for association with breast cancer risk using a nested case:control group of benign breast biopsies from women in our cohort who subsequently developed breast cancer (N = 85) vs those who did not (N = 142) and for whom LI status at the time of initial biopsy was known.
Conclusions: LI may decrease cancer risk through inhibition of key tumorigenic processes. Identification of processes associated with the physiologic risk reduction seen with LI may provide insight into novel avenues for risk reduction.
Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-06-01.
Abstract P6-06-04: p53 and p16 as Modifiers of HERV-K in Invasive Pleomorphic Lobular Carcinoma and Classic Lobular Carcinoma of Breast
Authors: Dadfarnia Tahereh , Xu Ya , Hatch Sandra S , Dong Jianli , Eltorky Mahmoud A 
Published: August 2014

Abstract
Withdrawn by Author
Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P6-06-04.