CC chemokine ligand 2 (CCL2) stimulates aromatase gene expression in mammary adipose tissue.

Obesity is a risk factor for postmenopausal breast cancer. Obesity-related inflammation upregulates aromatase expression, the rate-limiting enzyme for estrogen synthesis, in breast adipose tissue (BAT), increasing estrogen production and cancer risk. The regulation of aromatase gene (CYP19A1) in BAT is complex, and the mechanisms linking obesity and aromatase dysregulation are not fully understood. An obesity-associated factor that could regulate aromatase is the CC chemokine ligand (CCL) 2, a pro-inflammatory factor that also activates signaling pathways implicated in CYP19A1 transcription. By using human primary breast adipose stromal cells (ASCs) and aromatase reporter (hARO-Luc) mouse mammary adipose explants, we demonstrated that CCL2 enhances the glucocorticoid-mediated CYP19A1 transcription. The potential mechanism involves the activation of PI.4 via ERK1/2 pathway. We also showed that CCL2 contributes to the pro-inflammatory milieu and aromatase expression in obesity, evidenced by increased expression of CCL2 and CYP19A1 in mammary tissues from obese hARO-Luc mice, and subcutaneous adipose tissue from obese women. In summary, our results indicate that postmenopausal obesity may promote CCL2 production in BAT, leading to exacerbation of the menopause-related inflammatory state and further stimulation of local aromatase and estrogens. These results provide new insights into the regulation of aromatase and may aid in finding approaches to prevent breast cancer.

Breast adipose tissue attenuation as a novel imaging biomarker for cardiometabolic risk.

BACKGROUND: Certain adipose tissue depots infer higher cardiometabolic risk than body mass index (BMI). PURPOSE: To assess breast adipose tissue (BrAT) attenuation as a novel imaging biomarker for cardiometabolic risk. MATERIAL AND METHODS: We studied 151 women (mean age = 56 ± 1 years) across the weight spectrum. BrAT attenuation, abdominal adipose tissue cross-sectional areas (CSA), and attenuation were quantified using non-contrast computed tomography (CT) scans. Cardiometabolic risk factors were assessed from medical records. RESULTS: BrAT attenuation was lower in obese women compared to lean women. BrAT attenuation was inversely associated with BMI, waist circumference, abdominal fat CSA, fasting glucose, and triglycerides (P ≤ 0.02), and positively associated with abdominal adipose tissue attenuation (P < 0.001). BrAT attenuation had a sensitivity of 90% but a specificity of only 35% in detecting the metabolic syndrome (area under the curve = 0.63). CONCLUSION: BrAT attenuation is associated with cardiometabolic risk markers and could serve as an imaging biomarker for opportunistic risk assessment in patients undergoing CT examination of the chest.

Detection of crown-like structures in breast adipose tissue and clinical outcomes among African-American and White women with breast cancer.

BACKGROUND: Crown-like structures in breast adipose tissue (CLS-B), composed of necrotic adipocytes encircled by macrophages, are associated with obesity and hypothesized to worsen breast cancer prognosis; however, data are sparse, particularly in multi-racial populations. METHODS: We assessed specimens for CLS-B from 174 African-American and 168 White women with stage I-III breast cancer treated by mastectomy. Benign breast tissue from an uninvolved quadrant was immunohistochemically stained for CD68 to determine CLS-B presence and density (per cm2 of adipose tissue). Demographic and lifestyle factors, collected via medical record review, were analyzed for associations with CLS-B using logistic regression. Multivariable Cox proportional hazards models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between CLS-B and overall (OS) or progression-free (PFS) survival. RESULTS: Detection of any CLS-B was similar between African-American (32%) and White (29%) patients with no evidence of an association between race and CLS-B in multivariable models (OR = 0.82, 95% CI = 0.49-1.36). Detection of CLS-B was associated with obesity (OR = 4.73, 95% CI = 2.48-9.01) and age ≥ 60 years at diagnosis (OR = 1.78, 95% CI = 0.99-3.21). There was some evidence of associations with parity and current smoking status. Detection of CLS-B was not associated with OS (HR = 1.02, 95% CI = 0.55-1.87) or PFS (HR = 0.99, 95% CI = 0.59-1.67). CONCLUSIONS: Our results show a strong, positive association between BMI and CLS-B in non-tumor tissue similar to previous findings. Detection of CLS-B did not vary by race and was not associated with worse OS or PFS.

The Importance of Breast Adipose Tissue in Breast Cancer.

Adipose tissue is a complex endocrine organ, with a role in obesity and cancer. Adipose tissue is generally linked to excessive body fat, and it is well known that the female breast is rich in adipose tissue. Hence, one can wonder: what is the role of adipose tissue in the breast and why is it required? Adipose tissue as an organ consists of adipocytes, an extracellular matrix (ECM) and immune cells, with a significant role in the dynamics of breast changes throughout the life span of a female breast from puberty, pregnancy, lactation and involution. In this review, we will discuss the importance of breast adipose tissue in breast development and its involvement in breast changes happening during pregnancy, lactation and involution. We will focus on understanding the biology of breast adipose tissue, with an overview on its involvement in the various steps of breast cancer development and progression. The interaction between the breast adipose tissue surrounding cancer cells and vice-versa modifies the tumor microenvironment in favor of cancer. Understanding this mutual interaction and the role of breast adipose tissue in the tumor microenvironment could potentially raise the possibility of overcoming breast adipose tissue mediated resistance to therapies and finding novel candidates to target breast cancer.

Qualitative and quantitative differences in estrogen biotransformation in human breast glandular and adipose tissues: implications for studies using mammary biospecimens.

Because of its assumed role in breast cancer etiology, estrogen biotransformation (and interaction of compounds therewith) has been investigated in human biospecimens for decades. However, little attention has been paid to the well-known fact that large inter-individual variations exist in the proportion of breast glandular (GLT) and adipose (ADT) tissues and less to adequate tissue characterization. To assess the relevance of this, the present study compares estrogen biotransformation in GLT and ADT. GLT and ADT were isolated from 47 reduction mammoplasty specimens derived from women without breast cancer and were characterized histologically and by their percentages of oil. Levels of 12 unconjugated and five conjugated estrogens were analyzed by GC- and UHPLC-MS/MS, respectively, and levels of 27 transcripts encoding proteins involved in estrogen biotransformation by Taqman® probe-based PCR. Unexpectedly, one-third of specimens provided neat GLT only after cryosection. Whereas 17ß-estradiol, estrone, and estrone-3-sulfate were detected in both tissues, estrone-3-glucuronide and 2-methoxy-estrone were detected predominately in GLT and ADT, respectively. Estrogen levels as well as ratios 17ß-estradiol/estrone and estrone-3-sulfate/estrone differed significantly between GLT and ADT, yet less than between individuals. Furthermore, estrogen levels in GLT and ADT correlated significantly with each other. In contrast, levels of most transcripts encoding enzymes involved in biotransformation differed more than between individuals and did not correlate between ADT and GLT. Thus, mixed breast tissues (and plasma) will not provide meaningful information on local estrogen biotransformation (and interaction of compounds therewith) whereas relative changes in 17ß-estradiol levels may be investigated in the more abundant ADT.

Breast adiposity: Menopausal status impact and its influence on glycemic and anthropometric metabolic parameters.

CONTEXT: Ectopic fat depots are related to the deregulation of energy homeostasis, leading to diseases related to obesity and metabolic syndrome (MS). Despite significant changes in body composition over women's lifespan, little is known about the role of breast adipose tissue (BrAT) and its possible utilization as an ectopic fat depot in women of different menopausal statuses. OBJECTIVE: We aimed to assess the relationship between BrAT and metabolic glycemic and lipid profiles and body composition parameters in adult women. METHODS: In this cross-sectional study, we enrolled adult women undergoing routine mammograms to perform history and physical examination, body composition assessment, semi-automated assessment of breast adiposity (BA) from mammograms and fasting blood collection for biochemical analysis. Correlations and multivariate regression analysis were used to examine the associations of the BA with metabolic and body composition parameters. RESULTS: Of the 101 participants included in the final analysis, 76.2% were in menopause, and 23.8% were in premenopause. The BA was positively related with fasting plasma glucose, glycated hemoglobin, homeostasis model assessment of insulin resistance, body mass index, waist circumference, body fat percentage, abdominal visceral and subcutaneous fat when adjusted for age among women in postmenopause. Also, the BA was an independent predictor of hyperglycemia and metabolic syndrome. These associations were not present among women in premenopause. CONCLUSION: The BA was related to different adverse body composition and metabolic factors in women in postmenopause. The results suggest that there might be a relevant BrAT endocrine role during menopause, whose mechanisms are yet to be clarified, which thus opens up research perspectives on the subject as well as on clinical settings.

Peritumoral adipose tissue promotes lipolysis and white adipocytes browning by paracrine action.

Background: Stromal adipocytes and tumor breast epithelial cells undergo a mutual metabolic adaptation within tumor microenvironment. Therefore, browning and lipolysis occur in cancer associated adipocytes (CAA). However, the paracrine effects of CAA on lipid metabolism and microenvironment remodeling remain poorly understood. Methods: To analyze these changes, we evaluated the effects of factors in conditioned media (CM) derived from explants of human breast adipose tissue from tumor (hATT) or normal (hATN) on morphology, degree of browning, the levels of adiposity, maturity, and lipolytic-related markers in 3T3-L1 white adipocytes by Western blot, indirect immunofluorescence and lipolytic assay. We analyzed subcellular localization of UCP1, perilipin 1 (Plin1), HSL and ATGL in adipocytes incubated with different CM by indirect immunofluorescence. Additionally, we evaluated changes in adipocyte intracellular signal pathways. Results: We found that adipocytes incubated with hATT-CM displayed characteristics that morphologically resembled beige/brown adipocytes with smaller cell size and higher number of small and micro lipid droplets (LDs), with less triglyceride content. Both, hATT-CM and hATN-CM, increased Pref-1, C/EBPß LIP/LAP ratio, PPARγ, and caveolin 1 expression in white adipocytes. UCP1, PGC1α and TOMM20 increased only in adipocytes that were treated with hATT-CM. Also, hATT-CM increased the levels of Plin1 and HSL, while decreased ATGL. hATT-CM modified the subcellular localization of the lipolytic markers, favoring their relative content around micro-LDs and induced Plin1 segregation. Furthermore, the levels of p-HSL, p-ERK and p-AKT increased in white adipocytes after incubation with hATT-CM. Conclusions: In summary, these findings allow us to conclude that adipocytes attached to the tumor could induce white adipocyte browning and increase lipolysis as a means for endocrine/paracrine signaling. Thus, adipocytes from the tumor microenvironment exhibit an activated phenotype that could have been induced not only by secreted soluble factors from tumor cells but also by paracrine action from other adipocytes present in this microenvironment, suggesting a "domino effect".

Cancer-educated mammary adipose tissue-derived stromal/stem cells in obesity and breast cancer: spatial regulation and function.

BACKGROUND: Breast cancer is the most frequently diagnosed cancer and a common cause of cancer-related death in women. It is well recognized that obesity is associated with an enhanced risk of more aggressive breast cancer as well as reduced patient survival. Breast adipose tissue-derived mesenchymal stromal/stem cells (bASCs) are crucial components of the tumor microenvironment. A key step initially involved in this process might be the de-differentiation of bASCs into tumor supporting phenotypes. METHODS: In the present work, we isolated bASCs from adipose tissues adjacent to the tumor (aT bASCs) from lean- (ln-aT bASCs, BMI ≤ 25) and breast cancer patients with obesity (ob-aT bASCs, BMI ≥ 35), and analyzed their phenotypes with functional assays and RNA sequencing, compared to their counterparts isolated from adipose tissues distant from the tumor (dT bASCs). RESULTS: We show that ln-aT bASCs are susceptible to be transformed into an inflammatory cancer-associated phenotype, whereas ob-aT bASCs are prone to be cancer-educated into a myofibroblastic phenotype. Both ln-aT- and ob-aT bASCs compromise their physiological differentiation capacity, and upregulate metastasis-promoting factors. While ln-aT bASCs stimulate proliferation, motility and chemoresistance by inducing epithelial-mesenchymal transition of low malignant breast cancer cells, ob-aT bASCs trigger more efficiently a cancer stem cell phenotype in highly malignant breast cancer cells. CONCLUSION: Breast cancer-associated bASCs are able to foster malignancy of breast cancer cells by multiple mechanisms, especially, induction of epithelial-mesenchymal transition and activation of stemness-associated genes in breast cancer cells. Blocking the de-differentiation of bASCs in the tumor microenvironment could be a novel strategy to develop an effective intervention for breast cancer patients. SIGNIFICANCE: This study provides mechanistic insights into how obesity affects the phenotype of bASCs in the TME. Moreover, it highlights the molecular changes inside breast cancer cells upon cell-cell interaction with cancer-educated bASCs.

Distinct Shades of Adipocytes Control the Metabolic Roles of Adipose Tissues: From Their Origins to Their Relevance for Medical Applications.

Adipose tissue resides in specific depots scattered in peripheral or deeper locations all over the body and it enwraps most of the organs. This tissue is always in a dynamic evolution as it must adapt to the metabolic demand and constraints. It exhibits also endocrine functions important to regulate energy homeostasis. This complex organ is composed of depots able to produce opposite functions to monitor energy: the so called white adipose tissue acts to store energy as triglycerides preventing ectopic fat deposition while the brown adipose depots dissipate it. It is composed of many cell types. Different types of adipocytes constitute the mature cells specialized to store or burn energy. Immature adipose progenitors (AP) presenting stem cells properties contribute not only to the maintenance but also to the expansion of this tissue as observed in overweight or obese individuals. They display a high regeneration potential offering a great interest for cell therapy. In this review, we will depict the attributes of the distinct types of adipocytes and their contribution to the function and metabolic features of adipose tissue. We will examine the specific role and properties of distinct depots according to their location. We will consider their cellular heterogeneity to present an updated picture of this sophisticated tissue. We will also introduce new trends pointing out a rational targeting of adipose tissue for medical applications.

Immunomodulatory and Antioxidative potentials of adipose-derived Mesenchymal stem cells isolated from breast versus abdominal tissue: a comparative study.

BACKGROUND: Adipose-derived stem cells (ASCs) are considered ideal candidates for both research and cellular therapy due to ease of access, large yield, feasibility, and efficacy in preclinical and clinical studies. Unlike the subcutaneous abdominal fat depot, breast ASCs features are still not well recognized, limiting their possible therapeutic use. ASCs were found to exert immunomodulatory and antioxidative activities for maintaining homeostasis and functionality of diseased/damaged tissues. This study aims to investigate the immunomodulatory and antioxidative potentials of breast versus abdominal isolated ASCs to find out which anatomical site provides ASCs with better immunoregulatory and oxidative stress resistance capabilities. METHODS: ASCs were isolated from abdominal and breast tissues. Gene expression analysis was conducted for a panel of immunomodulatory and antioxidative genes, as well as adipokines and proliferation genes. Flow cytometric analysis of a group of immunomodulatory surface proteins was also performed. Finally, the significantly expressed genes have undergone protein-protein interaction and functional enrichment in silico analyses. RESULTS: Our results revealed similar morphological and phenotypic characteristics for both breast and abdominal ASCs. However, a significant elevation in the expression of two potent immunosuppressive genes, IL-10 and IDO as well as the expression of the multifaceted immunomodulatory adipokine, visfatin, was detected in breast versus abdominal ASCs. Moreover, a significant overexpression of the antioxidative genes, GPX1, SIRT5, and STAT3 and the proliferation marker, Ki67, was also observed in breast ASCs relative to abdominal ones. In silico analysis showed that both of the differentially upregulated immunomodulatory and antioxidative mediators integratively involved in multiple biological processes and pathways indicating their functional association. CONCLUSION: Breast ASCs possess superior immunomodulatory and antioxidative capabilities over abdominal ASCs. Our findings shed light on the possible therapeutic applications of breast ASCs in immune-related and oxidative stress-associated diseases.

Human breast adipose tissue: characterization of factors that change during tumor progression in human breast cancer.

BACKGROUND: Adipose microenvironment is involved in signaling pathways that influence breast cancer. We aim to characterize factors that are modified: 1) in tumor and non tumor human breast epithelial cell lines when incubated with conditioned media (CMs) from human breast cancer adipose tissue explants (hATT) or normal breast adipose tissue explants (hATN); 2) in hATN-CMs vs hATT-CMs; 3) in the tumor associated adipocytes vs. non tumor associated adipocytes. METHODS: We used hATN or hATT- CMs on tumor and non-tumor breast cancer cell lines. We evaluated changes in versican, CD44, ADAMTS1 and Adipo R1 expression on cell lines or in the different CMs. In addition we evaluated changes in the morphology and expression of these factors in slices of the different adipose tissues. The statistical significance between different experimental conditions was evaluated by one-way ANOVA. Tukey's post-hoc tests were performed within each individual treatment. RESULTS: hATT-CMs increase versican, CD44, ADAMTS1 and Adipo R1 expression in breast cancer epithelial cells. Furthermore, hATT-CMs present higher levels of versican expression compared to hATN-CMs. In addition, we observed a loss of effect in cellular migration when we pre-incubated hATT-CMs with chondroitinase ABC, which cleaves GAGs chains bound to the versican core protein, thus losing the ability to bind to CD44. Adipocytes associated with the invasive front are reduced in size compared to adipocytes that are farther away. Also, hATT adipocytes express significantly higher amounts of versican, CD44 and Adipo R1, and significantly lower amounts of adiponectin and perilipin, unlike hATN adipocytes. CONCLUSIONS: We conclude that hATT secrete a different set of proteins compared to hATN. Furthermore, versican, a proteoglycan that is overexpressed in hATT-CMs compared to hATN-CMs, might be involved in the tumorogenic behavior observed in both cell lines employed. In addition, we may conclude that adipocytes from the tumor microenvironment show a less differentiated state than adipocytes from normal microenvironment. This would indicate a loss of normal functions in mature adipocytes (such as energy storage), in support of others that might favor tumor growth.

Incorporation of eicosapentaenioic and docosahexaenoic acids into breast adipose tissue of women at high risk of breast cancer: a randomized clinical trial of dietary fish and n-3 fatty acid capsules.

SCOPE: The fatty acid profile of dietary lipids is reflected in mammary adipose tissue and may influence mammary gland biology and cancer risk. To determine the effects of fish consumption on breast adipose tissue fatty acids, we conducted a study of fish versus n-3 PUFA supplements in women at increased risk of breast cancer. METHODS AND RESULTS: High risk women were randomized to comparable doses of marine n-3 PUFAs as canned salmon + albacore or capsules for 3 months. Pre- and posttreatment fatty acid profiles were obtained by GC. Dietary fish (n = 12) and n-3 PUFA capsules (n = 13) yielded increased eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in plasma (p < 0.0001), erythrocyte membranes (p < 0.0001), and breast fat (p < 0.01) at 3 months. Women taking capsules had higher plasma and erythrocyte membrane EPA changes (∼four versus twofold, p = 0.002), without significant differences in DHA. Increases in breast adipose EPA, DHA were similar for both groups. Higher BMI correlated with smaller changes in plasma, erythrocyte membrane EPA, and breast adipose EPA, DHA. Adherence was excellent at 93.9% overall and higher in the fish arm (p = 0.01). CONCLUSION: Fish provides an excellent source of n-3 PUFAs that increases breast adipose EPA, DHA similar to supplements and represents a well-tolerated intervention for future studies of the impact of n-3 PUFAs and dietary patterns on breast cancer.