Mammary Fat Research Articles

Abstract 293: Distinctive roles of mammary adipomes in breast cancer progression: Insights from functional analysis and differential gene expression

Abstract Breast Cancer (BC) is a heterogeneous disease that impacts treatment response. This is due in part to the tumor microenvironment (TME), which contributes significantly to BC pathogenesis, including metastasis. Women with higher breast density and reduced breast fat face an increased BC risk across multiple tumor subtypes. This is exemplified by the correlation between increased tumor progression, the appearance of fibrosis and the loss of mature adipocytes. While the role of adipokines in this process has been studied extensively, the contribution of adipocyte-derived extracellular vesicles (EV) or "adipomes" in tumorigenesis and metastasis remains poorly understood. To address this question, we developed a novel technique for isolating intact adipomes from normal mammary fat (MF) obtained from wild-type C57BL/6 mice as well as from tumor-associated MF (TAMF) obtained from mice inoculated orthotopically with EO771 mammary tumor cells. Adipome isolation involved high-speed centrifugation to separate macro- and micro-vesicles, purification using the ExoQuick EV isolation system, and immunomagnetic capture of adipomes. Characterization of adipomes by transmission electron microscopy revealed two adipome populations, large L-adipomes of ~350 nm, and small S-adipomes of ~40 nm. Notably, the quantity of L-adipomes in tumor-associated mammary fat (TAMF) was 10-fold greater than the amount of L-adipomes in the MF of non-tumor-bearing mice. To identify possible functional roles of L-adipomes in the pathogenesis of BC, lipidomic profiling was undertaken. L-Adipomes from TAMF showed significantly altered lipid species in comparison to MF-derived L-adipomes. Adipomes were further characterized by treating EO771 cells for 72 hr with TAMF- or MF-derived adipomes at a cell to adipome ratio of 1:10, followed by RNAseq analysis. Differentially upregulated genes in TAMF-derived L-adipomes included Esr1, Erbb2, Tgfb1, Bcl2, MMP2, and Notch associated with fibrosis, EMT, angiogenesis and invasion and downregulation of genes linked to tumor suppression, apoptosis, and mitochondrial metabolism. Overall, our study illustrates the importance of tumor-associated adipomes in regulating gene expression in tumor cells, which emphasizes the specificity of adipome content relating to the cell-of-origin and the host's pathologic and metabolic state and in modulating signaling pathways involved in BC progression. Citation Format: Hariprasad Thangavel, Kezia Lizardo, Robert I. Glazer, Jyothi F. Nagajyothi. Distinctive roles of mammary adipomes in breast cancer progression: Insights from functional analysis and differential gene expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 293.

Abstract P2-20-03: Combination Therapy with an Anti-GD2 Antibody, Transforming Growth Factor Beta Imprinted Natural Killer Cells and Gemcitabine Improve Tumor Control and Survival in a Triple Negative Breast Cancer Model

Abstract Background: Intrinsic resistance to immunotherapy observed in breast cancer is attributed to low neoantigen levels, defective antigen presentation, low mutational burden, reduced programmed death ligand (PD-L1) expression and the presence of immunosuppressive signals like transforming growth factor-beta (TGFβ) in the tumor microenvironment (TME). These collectively attenuate the effector functions of T cells and natural killer cells (NK cells). NK cells are an important component of innate immunity. While generally TGFβ dampens the NK cell response in the breast cancer TME, chronic stimulation in vivo with TGFβ during the expansion process of donor NK cells produces TGFβ imprinted NK cells which exhibit high cytotoxicity and resistance to suppression by TGFβ due to down regulation of SMAD3 and hypersecretion of interferon gamma and tumor necrosis factor alpha. NK cell activation also promotes antibody dependent cellular cytotoxicity (ADCC) and augments monoclonal antibody directed killing. GD2 is a disialoganglioside and a tumor-associated antigen with limited expression in healthy tissues and overexpression in a variety of cancers, including breast cancer. Up to 60% of high grade breast cancers have GD2 expression with higher expression linked to worse overall survival. Given GD2 expression in aggressive BC subtypes and the role of NK cells in ADCC and antigen presentation, there is a strong rationale for evaluating an anti-GD2 antibody along with NK cells in the immunosuppressive breast TME. Based upon established preclinical data, we hypothesized that combining (1) an IgG1 anti-GD2 monoclonal antibody (anti-GD2), (2) TGFβ imprinted, IL-21 expanded allogenic universal donor NK cells (TGFβiNK) and (3) the standard chemotherapy agent gemcitabine (gem) which has immunomodulatory effects including improved NK cell function, will improve tumor control and survival in a TNBC mouse model. Methods: First, we evaluated if anti-GD2 treatment would increase ADCC against MD-MBA-231 tumor cells. To do this, tumor cells with or without anti-GD2 were cocultured with TGFβiNK + anti-GD2 and evaluated by real time cell analysis (RTCA). Next we evaluated the effect of gem on both tumor and immune cells. Finally to evaluate the effect of our novel combination therapy, female NSG mice were injected with 1 × 10e6 MDA-MB-231 cells into the mammary fat on day 0 and tumor burden was followed for 83 days. On day 21, mice were divided into 4 groups: control, gem only (standard of care), TGFβiNK+anti-GD2 (NK-GD2), and gem+TGFβiNK+anti-GD2 (G-NK-GD2) and tumor growth was measured weekly. Mice were observed for toxicity and bioluminescence evaluation for NK cells were performed prior to each cycle. Results: RTCA data confirmed anti-GD2 treatment increased ADCC mediated cell lysis by TGFβiNK. Furthermore, at clinically relevant doses, gem did not alter GD2 expression by flow cytometry on MDA-MB-231 tumor cells but induced MICA expression which suggests potential improved NK cell activity. In the mouse model, monitoring of mouse weights showed greater weight stability in the G-NK-GD2 group, suggesting a tolerable regimen. Serial measurement of tumors showed a significant reduction in tumor growth in NK-GD2 and G-NK-GD2 arms when compared to Gem or control. Additionally, mice who received G-NK-GD2 or NK-GD2 had significantly improved survival. Histological evaluation and immune assessment of the mice are ongoing. Conclusion: Our data showed no significant toxicities in the murine model and improved efficacy of G-NK-GD2 over the standard of care gemcitabine. Our preclinical data supports moving forward with a phase 1b/2 Bench-To-Bedside clinical trial, that will evaluate this combination in patients with aggressive subtypes of metastatic breast cancer where there is a great clinical need for effective treatments. Citation Format: Marcelo Pereira, Prashant Trikha, Sumithira Vasu, Zihai Li, Daniel Stover, Dean Lee, Margaret Gatti-Mays. Combination Therapy with an Anti-GD2 Antibody, Transforming Growth Factor Beta Imprinted Natural Killer Cells and Gemcitabine Improve Tumor Control and Survival in a Triple Negative Breast Cancer Model [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-20-03.

Abstract 1350: The role of phosphatidylserine scramblases in tumor progression

Abstract Introduction: Phosphatidylserine (PS), an anionic phospholipid, is asymmetrically distributed in the inner leaflet of the phospholipid bilayer in normal cells under homeostasis. However, PS is constitutively externalized in the tumor microenvironment (TME); on viable cells that undergo stress, such as hypoxic tumor cells, stressed tumor vascular endothelial cells, as well as on cells undergoing apoptosis. This high PS harbors a pro-tumorigenic micro-environment, as myeloid cells expressing PS receptors (Mertk, Tyro3 and Axl) engage with externalized PS and secrete immunosuppressive cytokines. PS is externalized on viable cells by a calcium activated scramblase TMEM16F and on apoptotic cells by a caspase activated scramblase called Xkr8. Here, to study the mechanisms by which PS is externalized in the TME, we hypothesize that TMEM16F and Xkr8 are the major scramblases responsible for creating an immune suppressive milieu in the tumor microenvironment. Methods: To study the mechanisms of PS dysregulation in the tumor microenvironment, TMEM16F and Xkr8 were knocked out in E0771 murine breast cancer cell line using CRISPR/Cas9. The knockouts were validated by western blotting, q-RT-PCR and surveyor assays. Results: TMEM16F KO E0771 cells express lower basal levels of PS compared to WT E0771 cells when detected by Annexin V staining by flow cytometry. TMEM16F KO cells are also less responsive to activation by calcium ionophore. TMEM16F KO, Xkr8 KO and WT E0771 cells have similar viability and migration patterns in response to Gas6, indicating that the cells themselves do not have altered oncogenic potential. TMEM16F KO E0771 cells injected into the inguinal mammary gland fat pad of C57BL6 syngeneic mice showed modest but significantly reduced tumor growth compared to the E0771 WT tumors, suggesting that TMEM16F mediated PS externalization could play a role in exacerbating tumor progression. Conclusion: TMEM16F driven PS externalization contributes to tumor growth. The effect of TMEM16F KO on immune regulation of the tumor milieu will be discussed. These data corroborate previous studies targeting PS in tumors therapeutically using anti-PS antibodies and suggests a role for scramblases in pleiotropic immune-suppression in the tumor. Citation Format: Varsha Gadiyar, Viralkumar Davra, David Calianese, Kevin Lahey, Raymond B. Birge. The role of phosphatidylserine scramblases in tumor progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1350.

Tumor-associated macrophage heterogeneity is driven by tissue territories in breast cancer.

Tissue-resident macrophages adapt to local signals within tissues to acquire specific functions. Neoplasia transforms the tissue, raising the question as to how the environmental perturbations contribute to tumor-associated macrophage (TAM) identity and functions. Combining single-cell RNA sequencing (scRNA-seq) with spatial localization of distinct TAM subsets by imaging, we discover that TAM transcriptomic programs follow two main differentiation paths according to their localization in the stroma or in the neoplastic epithelium of the mammary duct. Furthermore, this diversity is exclusively detected in a spontaneous tumor model and tracks the different tissue territories as well as the type of tumor lesion. These TAM subsets harbor distinct capacity to activate CD8+ Tcells and phagocyte tumor cells, supporting that specific tumor regions, rather than defined activation states, are the major drivers of TAM plasticity and heterogeneity. The distinctions created here provide a framework to design cancer treatment targeting specific TAM niches.

Abstract PS17-29: Surgically induced weight loss corrects obesity associated tumor progression and improves responsiveness to immunotherapy

Abstract Background: Obesity leads to a higher risk of cancer invasion, metastases, recurrence, mortality, and impaired therapeutic response through various mechanisms. One of these mechanisms is microenvironment dysfunction, where changes in immune cells, microbes, metabolites, and growth factors contribute to tumor aggressiveness. We study obesity-induced changes to the tumor microenvironment in Triple Negative Breast Cancer (TNBC), an aggressive subtype associated with obesity. The goal to compare tumor progression in lean vs. obese vs. weight loss manipulations to identify causal and targetable pathways associated with reprogramming the tumor microenvironment. Clinically, bariatric surgery induced weight loss reduced the risk of BC, with the greatest benefit detected in pre-menopausal patients with ER- tumors, like TNBC. We hypothesize surgically-induced weight loss will diminish obesity-associated tumor progression. Methods: To study weight gain and loss that best mimics human adiposity, we utilized obesogenic C57BL/6 females with a syngeneic orthotopic transplant of TNBC cells. Female mice placed on a high fat diet (HFD) at weaning became obese compared to mice on a low fat diet (LFD). After 16 weeks on an HFD diet, mice underwent the bariatric surgery Vertical Sleeve Gastrectomy (VSG). The VSG resulted in reduced body weight, adiposity, and correction of metabolic profiles compared to obese mice. Two weeks post-surgery, TNBC cells were OT into the mammary fat. Results: As expected, tumor growth was increased in obese mice compared to lean. Importantly, surgical weight loss rescued obese tumor progression. We identified key changes in tumor infiltrating of immune cells that could be responsible for the beneficial effects of bariatric surgery on tumor progression. We then exploited these changes with immunotherapy, which was uniquely effective in mice that underwent bariatric surgery. Conclusions: In conclusion obesity promotes a pro-tumor microenvironment, that can be corrected through surgically induced weight loss. Citation Format: Laura Sipe, Mehdi Chaib, Emily B Korba, Mary C Lovely, Jared C Clements, Neena A John, Ajeeth K Pingili, Joseph F Pierre, Liza Makowski. Surgically induced weight loss corrects obesity associated tumor progression and improves responsiveness to immunotherapy [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS17-29.

Thalidomide suppresses breast cancer tumor growth by inhibiting tumor-associated macrophage accumulation in breast tumor-bearing mice

we aimed to explore the role of thalidomide in breast cancer by using a mouse 4T1 breast tumor model. A tumor model was established by injecting logarithmic-phase 4T1 cells into the mammary fat pat.Tumor growth was monitored every day and tumor size was measured periodically. Which were performed to determine the cytokine and related gene mRNA expression, the cytokine production and protein expression, check the vessel formation and necrosis, the CD31 expression,the expression of CD31, F4/80 and CD206,staining the digested cells with F4/80, cd45 and CD11b to determine the M2 type macrophages accumulation by qRT-PCR, Cytokine antibody array, HE staining, Immunohistochemistry, Immunostaining, Flow cytometry, respectively. In the current study, Our results indicated that thalidomide significantly inhibited tumor growth in the mouse model by inhibiting angiogenesis and promoting the necrosis of tumor cells in tumor tissues.Moreover, immunostaining and flow cytometry results demonstrated that M2-type tumor-associated macrophage accumulation and infiltration were profoundly inhibited upon treatment with thalidomide. In addition, thalidomide treatment also regulated cytokine production by inhibiting the production of angiogenesis-related cytokines, such as G-CSF, VEGF-B, VEGFR1, VEGFR3 and IL-10. In conclusion, our studies explored the antitumor effect of thalidomide in a breast tumor model and uncovered that thalidomide inhibited breast tumor growth by inhibiting angiogenesis as a result of reducing TAM accumulation and infiltration and inhibiting angiogenesis-related cytokine production.

Multimodal Breast Phantoms for Microwave, Ultrasound, Mammography, Magnetic Resonance and Computed Tomography Imaging.

The aim of this work was to develop multimodal anthropomorphic breast phantoms suitable for evaluating the imaging performance of a recently-introduced Microwave Imaging (MWI) technique in comparison to the established diagnostic imaging modalities of Magnetic Resonance Imaging (MRI), Ultrasound (US), mammography and Computed Tomography (CT). MWI is an emerging technique with significant potential to supplement established imaging techniques to improve diagnostic confidence for breast cancer detection. To date, numerical simulations have been used to assess the different MWI scanning and image reconstruction algorithms in current use, while only a few clinical trials have been conducted. To bridge the gap between the numerical simulation environment and a more realistic diagnostic scenario, anthropomorphic phantoms which mimic breast tissues in terms of their heterogeneity, anatomy, morphology, and mechanical and dielectric characteristics, may be used. Key in this regard is achieving realism in the imaging appearance of the different healthy and pathologic tissue types for each of the modalities, taking into consideration the differing imaging and contrast mechanisms for each modality. Suitable phantoms can thus be used by radiologists to correlate image findings between the emerging MWI technique and the more familiar images generated by the conventional modalities. Two phantoms were developed in this study, representing difficult-to-image and easy-to-image patients: the former contained a complex boundary between the mammary fat and fibroglandular tissues, extracted from real patient MRI datasets, while the latter contained a simpler and less morphologically accurate interface. Both phantoms were otherwise identical, with tissue-mimicking materials (TMMs) developed to mimic skin, subcutaneous fat, fibroglandular tissue, tumor and pectoral muscle. The phantoms’ construction used non-toxic materials, and they were inexpensive and relatively easy to manufacture. Both phantoms were scanned using conventional modalities (MRI, US, mammography and CT) and a recently introduced MWI radar detection procedure called in-coherent Multiple Signal Classification (I-MUSIC). Clinically realistic artifact-free images of the anthropomorphic breast phantoms were obtained using the conventional imaging techniques as well as the emerging technique of MWI.

Abstract P4-14-11: Prolonged survival of mice bearing HER2 positive breast cancer with a therapeutic cancer vaccine via intra-reconstructed abdominal flap administration

Abstract Background: Previously we reported a porous silicon micro-particle based cancer vaccine, which stimulated robust CD8+ T cell-dependent anti-tumor immunity in mice bearing HER2-positive breast cancer. In this study we evaluated the efficacy of the vaccine via single injection into reconstructed abdominal flap after primary tumor mastectomy. Method: To generate murine model of HER2 positive breast cancer murine, 1 × 105 TUBO/luciferase cells were injectedinto both mammary gland fat pad and left ventricle of each 6-8 weeks old female Balb/c mice. Primary and systemic metastatic tumor growth were monitored with a IVIS-200 imaging system. Four days after tumor inoculation, mammary gland fat pad with primary tumor was resected by mastectomy, and superficial inferior epigastric(SIE) vessels based abdominal flap was used for abdominal reconstruction. During the surgery, mice also received one of the three treatments below: 1) negative control without treatments; 2) single intra-flap vaccination of cancer vaccine; and 3) single injection of cancer vaccine via footpad injection. Therapeutic efficacy were monitored with IVIS system weekly. To analyze immune response, popliteal and inguinal lymph nodes were collected one day and seven days post vaccination, and activation of dendritic cells and T cells was evaluated with a flow cytometry. HER2 specific T cells in splenocytes which highly expressed interferon-gamma (IFNγ) were counted by ELISpot. CD3+ T cell infiltration in brain metastatic nodules were analyzed by immunohistochemical assay. Result: Prolonged survival of mice bearing HER2-positive breast cancer was achieved by both intra-flap and intra-dermal vaccination of cancer vaccine. Mice vaccinated via intra-flap injection extended median survival by 9 days (p=0.025), although not as long as intra-dermal treatment (15 days, p=0.034), comparing to control group. In lymph nodes, activated dendritic cells increased in both two vaccinated groups. Interestingly, intra-flap vaccination induced higher response in inguinal lymph node, which considered as the major draining lymph node of this route. Meanwhile, intra-dermal vaccination raised higher immune response in popliteal lymph node. In ELISpot assay, IFNγ secreted T cells were found abundant in splenocytes from both two vaccination groups. Furthermore, efficient infiltration of T cells inside the brain metastatic nodules was found in intra-dermal injection group, which provided potential protection from distal recurrence after mastectomy. Conclusion: Cancer vaccine administrated via intra-flap injection effectively stimulated systemic immune response, and slowed down tumor progression in murine HER2 positive breast cancer model. Citation Format: Xiaoling Liu, Junhua Mai, Chaoyang Meng, Wei Wei, Haifa Shen. Prolonged survival of mice bearing HER2 positive breast cancer with a therapeutic cancer vaccine via intra-reconstructed abdominal flap administration [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-14-11.

Early breast development in overweight girls: does estrogen made by adipose tissue play a role?

BackgroundGirls who are overweight/obese (OB) develop breast tissue but do not undergo menarche (the first menstrual period) significantly earlier than girls of normal weight (NW). It has been proposed that estrogen synthesized by adipose tissue may be contributory, yet OB do not have higher serum estrogen levels than NW matched on breast stage. We hypothesized that estrogen synthesized locally, in mammary fat, may contribute to breast development. This hypothesis would predict that breast development would be more advanced than other estrogen-sensitive tissues as a function of obesity and body fat.Methods80 pre-menarchal girls (26 OB, 54 NW), aged 8.2–14.7 yrs, underwent dual-energy x-ray absorptiometry to calculate percent body fat (%BF), Tanner staging of the breast, breast ultrasound for morphological staging, trans-abdominal pelvic ultrasound, hand x-ray (bone age), a blood test for reproductive hormones, and urine collection to determine the vaginal maturation index (VMI), an index of estrogen exposure in urogenital epithelial cells.ResultsWhen controlling for breast morphological stage determined by ultrasound, %BF was not associated with serum estrogen or gonadotropin (LH and FSH) levels or on indices of systemic estrogen action (uterine volume, endometrial thickness, bone age advancement, and VMI). Tanner breast stage did not correlate with breast morphological stage and led to misclassification of chest fatty tissue as breast tissue in some OB.ConclusionsThese studies do not support the hypothesis that estrogen derived from total body fat or local (mammary) fat contributes to breast development in overweight/obese girls.

P019] Optimized tube voltage setting for contrast of the mammogram films

Purpose In analogue mammography, single-side emulsion mammographic films (s-s film) had been used. However, double-sided emulsion mammographic films (d-s film) were developed in 2010. The contrast of d-s films is higher than s-s films. Therefore, to optimized image contrast in the breast of the d-d films, the tube voltage is intended to increase to adjust image contrast. The image contrasts in the breast among the s-s film, the d-s film, and d-s film with tube voltage adjusted were analyzed. The image contrast in the breast was adjusted between s-s film and d-s film with increase tube voltage. Methods Thirty series of mammograms were evaluated among three groups. To determine of contrast, the density between mammary gland areas and fat areas were measured. One-way analysis of variance (ANOVA) among three kinds of images was carried out and post hock test was performed (SPSS Ver.2, IBM). Statistical significant level was set at 5 %. The study was conducted with the permission of the ethical review board of facilities. Results The contrasts in the breast between the s-s films (0.87 ± 0.29) and d-s film with adjusted tube voltage (0.96 ± 0.28) were no statistical significant (p > 0.05). However, the contrast in the breast between the s-s films (0.87 ± 0.29) and d-s films (1.17 ± 0.35) were statistically significant (p Conclusions To adjust contrast in the breast of the d-s film was same as s-s film, tube voltage should be increased 1 kV. Therefore, the similar contrast image in the breast was obtained by using d-s film.

Abstract 1106: A synthetic pre-metastatic niche mimic alters the primary tumor and tumor microenvironment

Abstract Background: Immune cells at the primary tumor (PT) and pre-metastatic niche (PMN) sites are critical to metastasis progression. Recently, synthetic biomaterial scaffolds used as PMN mimics were shown to capture both immune and metastatic tumor cells in vivo (1-3). The redirection of tumor cells toward the implant also reduces tumor burden and provides a survival benefit in orthotopic breast cancer mouse models (4). Given the scaffold reduces tumor burden, we hypothesized the scaffold modulates PT and immune cell phenotypes to generate an invasion-suppressive tumor microenvironment (TME). Methods: Female NOD scid gamma (NSG) mice inoculated with tdTomato+ MDA-MB-231BR cells in the mammary fat were used as orthotopic human breast cancer models. Poly(lactide-co-glycolide) scaffolds were implanted in the intraperitoneal fat pad 7 days post-tumor inoculation (3). Mock surgery mice did not receive an implant. After 28 days, mock vs. scaffold PTs were harvested, digested, and live-cell sorted to obtain tdTomato+ tumor cells and CD45+ immune cells. The PT cell transcriptome was analyzed using RNAseq and GO analysis was performed in Metascape. CD45+ immune cells were cultured to obtain conditioned media (CM) for secretomics analysis, in vitro tumor cell invasion assays, and transcription factor activity arrays (2). Immune cells, specifically tumor associated macrophages (TAMs) (5), were characterized using flow cytometry and RT-PCR. Results: RNAseq analysis identified 892 differentially expressed genes in tumor cells in response to the scaffold implant, and Metascape GO analysis revealed signaling pathways relevant to invasion. The scaffold immune-CM decreased tumor cell invasion more than two-fold relative to mock CM. Secretomics analysis showed an increase in the pan-metastasis inhibitor decorin and a decrease in invasion-promoting CCL2 in the scaffold immune cell CM relative to mock CM. Reduced NFkB, SRF, and RAR transcription factor activity in tumor cells treated with scaffold CM relative to mock CM indicate immune secreted factors contribute to the invasion-suppressive scaffold-influenced TME. Finally, analysis of PT immune cells identified a recruited TAM population whose transcriptomic profile may contribute to the invasion-suppressive TME in scaffold bearing mice. Discussion: We demonstrate that implanted scaffolds can distally modulate secretomic and transcriptional profiles of immune cells in the TME and may reduce PT cell invasion. Our work suggests scaffolds have an active role in modulating tumor burden and may provide a foundation for developing an effective implantable therapeutic tool.

GosB Inhibits Triacylglycerol Synthesis and Promotes Cell Survival in Mouse Mammary Epithelial Cells.

It has been demonstrated that the activator protein related transcription factor Finkel-Biskis-Jinkins murine osteosarcoma B (GosB) is involved in preadipocyte differentiation and triacylglycerol synthesis. However, the role of GosB in regulating the synthesis of milk fatty acid in mouse mammary glands remains unclear. This research uncovered potentially new roles of GosB in suppressing milk fatty acid synthesis. Results revealed that GosB had the highest expression in lung tissue and showed a higher expression level during nonlactation than during lactation. GosB inhibited the expression of fatty acid synthase (FASN), stearoyl-CoA desaturase (SCD), fatty acid binding protein 4 (FABP4), diacylglycerol acyltransferase 1 (DGAT1), perilipin 2 (PLIN2), perilipin 3 (PLIN3), and C/EBPα in mouse mammary gland epithelial cells (MEC). In addition, GosB reduced cellular triglyceride content and the accumulation of lipid droplets; in particular, GosB enhanced saturated fatty acid concentration (C16:0 and C18:0). The PPARγ agonist, rosiglitazone (ROSI), promoted apoptosis and inhibited cell proliferation. GosB increased the expression of Bcl-2 and protected MEC from ROSI-induced apoptosis. Furthermore, MECs were protected from apoptosis through the GosB regulation of intracellular calcium concentrations. These findings suggest that GosB may regulate mammary epithelial cells milk fat synthesis and apoptosis via PPARγ in mouse mammary glands.

Quercetin inhibits angiogenesis by targeting calcineurin in the xenograft model of human breast cancer

Vascular endothelial growth factor receptor 2 (VEGFR2) mediated calcineurin/nuclear factor of activated T-cells (NFAT) pathway is crucial in the angiogenesis of human breast cancer. Quercetin (Qu), a flavonoid known to possess anti-angiogenesis and antitumor properties, inhibited calcineurin activity in vitro. Herein, we performed a study in vivo to evaluate the effects of Qu on the angiogenesis in breast cancer. Female BALB/c nude mice were injected with MCF-7 cells into the mammary fat and were randomly divided into four groups. The animals were treated with vehicle solution, tamoxifen (TAM, 5.6mg/kg), tacrolimus (FK506, 3mg/kg), or Qu (34mg/kg) for 21 days, respectively. The results showed that, similar to TAM and FK506, Qu decreased tumor growth, limited oncocyte proliferation and promoted tumor necrosis. Anti-angiogenic actions of Qu were demonstrated as decreased serum VEGF (P<0.01), and sparse microvessel density (P<0.05). Qu significantly inhibited tumor calcineurin activities, and the inhibitory rate was 62.73% in Qu treated animals, compared to that was 72.90% in FK506 group (P>0.05). Effects of Qu on calcineurin/NFAT pathway were confirmed as decreased subcellular located levels of VEGF (P<0.05), VEGFR2 (P<0.05) and NFATc3 (P<0.01), downregulated gene expression of VEGF (P<0.05), VEGFR2 (P<0.05) and NFATc3 (P<0.01), reduced protein levels of VEGF (P<0.05), VEGFR2 (P<0.05), and NFATc3 (P<0.01) in tumor tissues. These findings indicate that Qu inhibit angiogenesis of human breast cancer xenograft in nude mice, which was associated with suppressing calcineurin activity and its regulated pathway activation.

Abstract P1-07-24: Modeling breast cancer metastasis in the mouse via measurement of circulating tumor cells

Abstract Objectives: Advances in the detection of circulating tumor cells (CTC) in the blood of metastatic breast cancer patients have indicated that patients with greater than 5 CTC/7.5mL of blood have poorer prognosis; however, little is known about the biology of these cells and what characteristics are critical for breast tumor cell dissemination. We are developing and evaluating several mouse models of breast cancer to characterize important markers that distinguish CTCs from other cell types in the blood as well as to assess whether silencing of various metastasis supporting genes leads to reductions in CTC counts and formation of metastatic tumors. Methods: This study involves two separate approaches to characterize CTCs. The first involves xenograft models using human breast cancer cells injected into the fat pad of immunocompromised mice. These cells are tagged with both mCherry, for detection in blood, and luciferase, to track metastatic spread of the primary tumor cells to other sites via intravital imaging. Blood was collected from tumor bearing mice at end point, processed and stained for characterized CTC markers. The second approach involves endogenous mouse models to characterize CTC counts and relevant markers in a variety of metastatic and non-metastatic murine breast cancer models using negative depletion to remove contaminating normal and hematopoietic cells. In both approaches CTCs have been assessed using the Imagestream by Amnis. Results: Initial xenograft experiments with MDA-MB-231 cells injected into the mouse mammary gland fat pad revealed a low concentration of mCherry+/cytokeratin+/Hoechst+/CD45- cells in the blood of mice without confirmed metastatic dissemination. Pilot studies on endogenous tumor models have demonstrated the utility of our negative depletion approach to remove contaminating hematopoietic cells as well as the detection of a population of EpCAM+/Hoechst+/CD45- cells. Conclusions: Initial experiments have provided feasibility for detailed characterization of mouse CTCs, which will be presented. This work complements our study being carried out on characterizing CTCs in metastatic breast cancer patients. Increasing understanding of the biology of circulating tumor cells and relating their characteristics to those of both the primary and metastatic tumors may reveal mediators common and functionally important to all 3 tumor cell populations and may therefore serve as better targets for treatments that are effective against both the primary and metastatic tumors. Citation Format: Jennifer L Gorman, Michael Parsons, Eldad Zacksenhaus, Sean Egan, Martin Chang, Jim R Woodgett. Modeling breast cancer metastasis in the mouse via measurement of circulating tumor cells [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-07-24.

Myoid hamartoma of the breast with focal chondromyoxid metaplasia and pseudoangiomatous stromal hyperplasia: A case report.

Hamartomas of the breast, also known as fibroadenolipomas, lipofibroadenomas or adenolipomas, are benign lesions. Hamartomas account for between 0.04 and 1.15% of all benign breast tumors in females. Myoid hamartoma of the breast (MHB) is extremely rare. The present study describes a case of MHB in a 44-year-old female. Screening mammography revealed a lobulated partial indistinct isodense mass measuring ~3.8 cm in the upper outer quadrant of the left breast. Sonographic examinations revealed a 2–3-cm mass in the left breast, which was fairly well circumbscribed and demonstrated complex scattered echogenic areas and isoechoic tissue. A core needle biopsy demonstrated fibrocystic changes, with small focal ductule aggregations. As malignancy could not be excluded, a partial mastectomy was performed using a circumareolar incision. The mass was histopathologically diagnosed as MHB with focal chondromyoxid metaplasia and pseudoangiomatous stromal hyperplasia. The histological diagnosis was based upon the findings of the well-circumscribed tumor, which was composed of entrapped mammary ducts, fat cells and myoid stromal components, with focal chondromyxoid metaplasia and pseudoangiomatous stromal hyperplasia. The tumor cells exhibited diffuse cluster of differentiation 34-positive immunoreactivity, which was consistent with a diagnosis of pseudoangiomatous stromal hyperplasia.

Abstract 3192: The environmental estrogen bisphenol A (BPA) regulates mammary gland stem cells

Abstract A study by the Centers for Disease Control revealed detectable levels of the environmental toxin Bisphenol A (BPA) in urine samples from over 92% of people in the NHANES (National Health and Nutrition Examination Survey) study. BPA is a small molecule used in the polymerization of polycarbonate plastics. These plastics are widely used in food containers, water bottles, dental fillings and toys, among many other products. BPA is similar to the synthetic estrogen diethylstilbesterol (DES) and can bind to estrogen receptor alpha (ERα) or estrogen receptor beta (ERβ). Because BPA is lipophilic and has been detected in mammary gland fat in humans, we hypothesize that BPA is an estrogen mimic in the stromal adipocytes in the breast and can induce stem cell proliferation and survival, leading to breast tumor formation. Indeed, BPA increases the size and number of mammospheres from normal mouse mammary gland and from human MCF7 breast cancer cells. Adipocytes co-cultured with mammospheres increased the size of the spheres, and BPA further increased the size of adipocyte co-cultured mammospheres. BPA upregulates the stem cell markers Nanog, OCT4 and SOX2 in mammospheres. ERα and pCREB were shown to bind to an enhancer downstream of the SOX2 gene after BPA treatment. Finally, BPA increased the size of tumor xenografts in NUDE mice. Together these experiments demonstrate that BPA may induce breast cancer via ERα and pCREB regulation of breast cancer stem cells. Citation Format: Cydney Nichols, Xiangming Ding, Gustavo Miranda-Carboni, Susan Amy Krum. The environmental estrogen bisphenol A (BPA) regulates mammary gland stem cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3192. doi:10.1158/1538-7445.AM2014-3192

Abstract 1162: Fibroblast RHAMM promotes breast cancer aggression by promoting expression of a subset of ERK1,2 target genes

Abstract The microenvironment plays a key role in cancer progression and metabolism of the extracellular matrix component hyaluronan (HA), a glycosaminoglycan, is associated with breast tumor progression. High molecular weight HA is degraded by hyaluronidases and free radicals to fragments of heterogeneous size, which accumulate in the peritumor stroma and activate signaling pathways in both tumor and stromal cells. The HA receptor RHAMM is a multifunctional protein that is found on the cell surface, inside the nucleus and the mitotic spindles of mesenchymal cells. RHAMM expression and HA accumulation in the tumor stroma are linked to breast tumor progression, predicting that RHAMM/HA regulated signaling is key to breast cancer progression. An N-terminally truncated RHAMM isoform, RHAMMonc, is oncogenic when overexpressed in mesenchymal cells. Intracellular RHAMMonc directly binds to ERK1, and complexes with ERK1,2 and MEK1. Intracellular RHAMM is required for sustained ERK1,2 activation and for nuclear localization of a subset of active ERK1,2. We hypothesized that this function results in expression of oncogenic proteins that support breast cancer cell aggression. Study purpose: determine the mechanism for RHAMMonc supported breast cancer aggression. Experimental procedure: we used microarray analysis in combination with real time PCR and ERK1,2 inhibition to identify genes that are upregulated in response to RHAMMonc overexpression. To determine whether nuclear RHAMMonc is required for neoplastic transformation we added a nuclear export signal to the RHAMMonc cDNA (RHAMMNES-onc). Mesenchymal cells overexpressing RHAMMonc or RHAMMNES-onc were injected into immune compromised mice. To test whether these cells could support in vivo growth of breast cancer cells, MCF7 cells were co-injected with RHAMMonc or RHAMMNES-onc expressing cells into the mammary gland fat pad. Tumor growth was quantified as tumor wet weight. Conclusion: Microarray analysis in combination with real time PCR identified altered expression of genes in all categories of the Hallmarks of Cancer in fibroblasts overexpressing RHAMMonc compared to parental cells. A subset of these were shown to be regulated by ERK1,2. Fusion of a nuclear export signal to RHAMMonc (RHAMMNES-onc) resulted in export of this protein from the nucleus, significant reduction of nuclear active ERK1,2 and modified expression of a subset of ERK1,2 regulated genes (e.g. LOX, MMP9, CDH11). Importantly, forced nuclear export of RHAMMonc suppressed its oncogenic effect on fibroblasts. Furthermore, proliferation of human MCF7 breast cancer cell xenografts was strongly stimulated by co-injection with RHAMMonc fibroblasts but this stimulatory effect was lost when MCF7 tumor cells were co-injected with RHAMMNES-onc. This study suggests that nuclear RHAMMonc:ERK 1,2 interactions control an oncogenic program in fibroblasts that support breast cancer aggression. Citation Format: Cornelia Toelg, Patrick Telmer, Sara Hamilton, James McCarthy, Eva Turley. Fibroblast RHAMM promotes breast cancer aggression by promoting expression of a subset of ERK1,2 target genes. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1162. doi:10.1158/1538-7445.AM2014-1162

Experimental hypothyroidism increases apoptosis in dimethylbenzanthracene-induced mammary tumors

Epidemiological and in vitro data have not provided conclusive evidence concerning the involvement of thyroid hormones (THs) on mammary carcinogenesis. We used an in vivo model to assess the relationship between THs, adipose tissue and breast cancer development. Female Sprague‑Dawley rats were treated with a dose of 7,12-dimethylbenz(a)anthracene (15 mg/rat) at 55 days of age and were then divided into four experimental groups: hypothyroid rats (HypoT, 0.01% 6-N-propyl-2-thiouracil in drinking water), untreated control (EUT); hyperthyroid rats (HyperT, 0.25 mg/kg/day T4 s.c.) and vehicle-treated control rats. The latency of tumor appearance and the incidence and progression of tumors were determined. At sacrifice, blood samples were collected for hormone determinations and samples of tumor and mammary glands were obtained for immunohistological studies. HypoT rats had retarded growth and an increase in mammary fat. The latency was longer (p<0.0001), the incidence rate was lower (p<0.05) and tumor growth was slower in HypoT rats compared to EUT and HyperT rats. Mitotic index and PCNA immunostaining were similar in all groups. HypoT rats showed increased apoptosis (p<0.05) as evaluated by the apoptotic index and TUNEL staining. No differences in serum prolactin and progesterone were observed. However, circulating estradiol (E2) was significantly lower in HypoT and HyperT rats. Serum leptin levels were reduced in HypoT rats even though the abdominal fat mass was similar in all groups. To note, the leptin level was higher in HypoT rats that developed mammary tumors than the level in non-tumoral HypoT rats. In conclusion, hypothyroidism altered animal growth, breast morphology, body composition, leptin secretion and serum E2 enhancing apoptosis and, consequently, retarding mammary carcinogenesis in rats.

Abstract 1354: Chronic social stress in a mouse model of triple-negative breast cancer is associated with oncogenic changes in mammary fat.

Abstract Chronic social isolation is linked to increased mammary tumor growth in rodent models of breast cancer. In the C3(1)/SV40 T-antigen (Tag) FVB/N mouse model of “triple-negative” breast cancer, the heightened stress response elicited by social isolation has been associated with increased expression of metabolic genes in the mammary gland before invasive tumors develop (i.e. during the in situ carcinoma stage). To further understand how underlying accelerated mammary tumor growth is associated with social isolation, we separated the mammary gland adipose tissue from adjacent ductal epithelial cells and analyzed individual cell types for changes in metabolic gene expression. Specifically, increased expression of the key metabolic genes Acaca, Hk2 and Acly was found primarily in the adipocyte, rather than epithelial fraction. Increased metabolic gene expression in the mammary adipocytes of socially isolated mice coincided with increased glucose metabolism, lipid synthesis, and leptin expression. Furthermore, culture media from isolated mouse mammary adipose tissue resulted in relatively increased proliferation and decreased apoptosis of mammary epithelial cancer cells derived from the same mouse strain. Additional gene expression analyses identified significant upregulation of the novel carbohydrate response element binding protein beta isoform (CHREBP-β) in socially isolated mammary fat. We hypothesize that the response to social isolation induces metabolic changes in mammary fat that are coordinated through CHREBP-β and are pro-oncogenic. We are currently performing global lipidomic and metabolomic analyses of mammary adipose tissue and secreted culture media to identify bioactive molecules involved in tumor growth. Citation Format: Paul A. Volden, Erin Wonder, Maxwell Skor, Feenalie Patel, Martha McClintock, Matthew Brady, Suzanne Conzen. Chronic social stress in a mouse model of triple-negative breast cancer is associated with oncogenic changes in mammary fat. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1354. doi:10.1158/1538-7445.AM2013-1354

Abstract 2093: Sunitinib suppresses the proliferation, migration, apoptosis resistance, tumor angiogenesis and growth in MDA-MB-468 cell cultures and xenografts .

Abstract We previously reported the anti-tumor efficacy of sunitinib (VEGF receptor tyrosine kinase inhibitor) in murine ER-positive breast cancer xenograft model, in which sunitinib suppressed both autocrine and paracrine effects in breast cancer progression. The investigations of sunitinib on triple-negative breast cancer are very limited. The clinical utility of sunitinib is less understood in the setting of breast cancer. The present study determines: 1) whether VEGF is highly expressed in MDA-MB-468 cells, compared to MCF-7 and MDA-MB-231 cells; 2) whether sunitinib inhibits the proliferation, migration, apoptosis resistance of cultured MDA-MB-468 cells; 3) whether oral sunitinib treatment suppresses tumor angiogenesis and growth in MDA-MB-468 xenografts; and 4) whether sunitinib changes % of breast cancer stem cells in the xenografts. MDA-MB-231, MDA-MB-468, MCF-7 cells were cultured using RPMI 1640 media with 10% FBS. VEGF protein levels were detected using ELISA (R&amp;D Systams). MDA-MB-468 cells were exposed to sunitinib for 18 hours for measuring proliferation (3H-thymidine incorporation), migration (BD BioCoat Matrigel Invasion Chamber), and apoptosis (Millipore ApopTag). 10ˆ6 MDA-MB-468 cells inoculated into the left fourth mammary gland fat pad in athymic nude-foxn1 mice. When the tumor volume reached 100 mmˆ3, sunitinib was given by gavage at 80 mg/kg/2 days for 4 weeks. Tumor angiogenesis was determined by CD31 immunohistochemistry. Breast cancer stem cells were determined by flow cytometry analysis using CD44+/CD24- or low. VEGF protein levels in MDA-MB-468 cells were 10257±292 pg/ml that are 3-folds higher than those (3428±74 pg/ml) in MDA-MB-231 cells and 31-folds higher than those (335±4 pg/ml) in MCF-7 cells (P&amp;lt;0.01, n=6). 1, 5 and 10 μmol/L of sunitinib caused 24, 41 and 59% reduction in the proliferation of MDA-MB-468 cells, respectively, compared to the control (P&amp;lt;0.01, n=6). Sunitinib at 1 μmol/L significantly inhibited the migration of MDA-MB-468 cells by 45% compared to the control (P&amp;lt;0.01, n=6). Sunitinib (5 μmol/L) increased 31% apoptosis of MDA-MB-468 cells (P&amp;lt;0.01). Oral sunitinib treatment significantly inhibited tumor angiogenesis and tumor growth, and slightly increased % of breast cancer stem cells in the xenografts. These findings suggest that VEGF is highly expressed in triple negative breast cancer (TNBC) cells especially in MDA-MB-468 cells. VEGF receptor tyrosine kinase inhibitor (sunitinib) can inhibit autocrine effects (proliferation, migration, and apoptosis resistance) and paracrine effects (tumor angiogenesis) in triple negative breast cancer progression. However, the possibility should be considered of sunitinib increasing breast cancer stem cells. Sunitinib or other anti-VEGF agents in TNBC therapy may have to be combined with cancer stem cell-targeting drugs. Citation Format: Edmund Chinchar, Kristina L. Makey, John Gibson, Lucio Miele, Jian-Wei Gu. Sunitinib suppresses the proliferation, migration, apoptosis resistance, tumor angiogenesis and growth in MDA-MB-468 cell cultures and xenografts . [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2093. doi:10.1158/1538-7445.AM2013-2093