The relation of leptin and adiponectin with breast density among premenopausal women

Lipidome of mammographic breast density in premenopausal women

BACKGROUND

High mammographic breast density (MBD) is a strong risk factor for breast cancer development, but the biological mechanisms underlying MBD are unclear. Lipids play important roles in cell differentiation, and perturbations in lipid metabolism are implicated in cancer development. Nevertheless, no study has applied untargeted lipidomics to profile the lipidome of MBD. Through this study, our goal is to characterize the lipidome of MBD in premenopausal women.

METHODS

Premenopausal women were recruited during their annual screening mammogram at the Washington University School of Medicine in St. Louis, MO. Untargeted lipidomic profiling for 982 lipid species was performed at Metabolon (Durham, NC®), and volumetric measures of MBD (volumetric percent density (VPD), dense volume (DV), and non-dense volume (NDV)) was assessed using Volpara 1.5 (Volpara Health®). We performed multivariable linear regression models to investigate the associations of lipid species with MBD and calculated the covariate-adjusted least square mean of MBD by quartiles of lipid species. MBD measures were log10 transformed, and lipid species were standardized. Linear coefficients of MBD were back-transformed and considered significant if the Bonferroni corrected p-value was < 0.05.

RESULTS

Of the 705 premenopausal women, 72% were non-Hispanic white, and 23% were non-Hispanic black. Mean age, and BMI were 46 years and 30 kg/m2, respectively. Fifty-six lipid species were significantly associated with VPD (52 inversely and 4 positively). The lipid species with positive associations were phosphatidylcholine (PC)(18:1/18:1), lysophosphatidylcholine (LPC)(18:1), lactosylceramide (LCER)(14:0), and phosphatidylinositol (PI)(18:1/18:1). VPD increased across quartiles of PI(18:1/18:1): (Q1 = 7.5%, Q2 = 7.7%, Q3 = 8.4%, Q4 = 9.4%, Bonferroni p-trend = 0.02). The lipid species that were inversely associated with VPD were mostly from the triacylglycerol (N = 43) and diacylglycerol (N = 7) sub-pathways. Lipid species explained some of the variation in VPD. The inclusion of lipid species increased the adjusted R2 from 0.45, for a model that includes known determinants of VPD, to 0.59.

CONCLUSIONS

We report novel lipid species that are associated with MBD in premenopausal women. Studies are needed to validate our results and the translational potential.

Associations between ADIPOQ rs2241766 SNP and breast cancer risk: a systematic review and a meta-analysis

Purpose

We aimed to conduct a meta-analysis to accurately evaluate the potential association between ADIPOQ rs2241766 gene SNP and breast cancer risk.

Methods

A systematic literature search on Cochrane Library, PubMed, Embase, Web of Science and China National Knowledge Infrastructure (CNKI) identified 8 articles with 1692 cases and 1890 controls. Strength of association was evaluated by pooled odds ratio (OR), 95 % confidence interval (CI) and p value. Funnel plots and Begger’s regression test were applied for testing the publication bias. Statistical analysis of all data was performed by Stata 12.0.

Results

The meta-analysis results indicated that the ADIPOQ rs2241766 gene polymorphism did not significantly associated with the risk of breast cancer for these genetic models (TT vs. TG + GG: OR = 1.20, 95 % CI = 0.77–1.89, p=0.417; TT + TG vs. GG: OR = 1.05, 95 % CI = 0.71–1.56, p=0.805; T vs. G: OR =1.17, 95 % CI = 0.79–1.74, p=0.437).

Conclusions

This study indicated that no significant relationship between the ADIPOQ rs2241766 SNP and breast cancer. Further large-scale and well-designed studies will be indispensable to confirm our result.

Association between expression of inflammatory markers in normal breast tissue and mammographic density among premenopausal and postmenopausal women

OBJECTIVE

Inflammatory markers may be associated with breast cancer risk. We assessed the association between expression levels of proinflammatory (interleukin 6, tumor necrosis factor-α, C-reactive protein, cyclooxygenase 2, leptin, serum amyloid A1, interleukin 8, and signal transducer and activator of transcription 3) and anti-inflammatory markers (transforming growth factor-β, interleukin 10, and lactoferrin) in normal breast tissue with mammographic density, a strong breast cancer risk indicator, among 163 breast cancer patients.

METHODS

The expression of inflammatory markers was visually evaluated on immunohistochemistry stained slides. The percent mammographic density (PMD) was estimated by a computer-assisted method in the contralateral cancer-free breast. We used generalized linear models to estimate means of PMD by median expression levels of the inflammatory markers while adjusting for age and waist circumference.

RESULTS

Higher expression levels (above median) of the proinflammatory marker interleukin 6 were associated with higher PMD among all women (24.1% vs 18.5%, P = 0.007). Similarly, higher expression levels (above median) of the proinflammatory markers (interleukin 6, tumor necrosis factor-α, C-reactive protein, and interleukin 8) were associated with higher PMD among premenopausal women (absolute difference in the PMD of 8.8% [P = 0.006], 7.7% [P = 0.022], 6.7% [P = 0.037], and 16.5% [P = 0.032], respectively). Higher expression levels (above median) of the anti-inflammatory marker transforming growth factor-β were associated with lower PMD among all (18.8% vs 24.3%, P = 0.005) and postmenopausal women (14.5% vs 20.7%, P = 0.013).

CONCLUSIONS

Our results provide support for the hypothesized role of inflammatory markers in breast carcinogenesis through their effects on mammographic density. Inflammatory markers could be targeted in future breast cancer prevention interventions.

Similar to Adiponectin, Serum Levels of Osteocalcin are Associated with Mammographic Breast Density in Postmenopausal Women

OBJECTIVE

Breast cancer is the most common type of cancer in Canadian women and worldwide. Mammographic density is a well-established breast cancer risk. Recent evidence suggested inverse correlations among adiponectin, osteocalcin, and the risk developing breast cancer. The objective of the study was to evaluate the relationship between breast density and adiponectin and osteocalcin concentrations.

METHODS

A cross-sectional study was performed in 239 women, age range 40 to 60. Mammographic density, serum adiponectin, and osteocalcin levels were measured. According to the Wolfe method, participants were divided into those with low-risk and high-risk pattern mammograms.

RESULTS

The study population included 107 premenopausal and 132 postmenopausal women. Parameters were no different between women with low-risk and high-risk patterns. In obese postmenopausal women, the high-risk pattern mammogram group had significantly higher values of adiponectin and osteocalcin compared with the low-risk pattern group. Multiple linear regression analyses showed that adiponectin and osteocalcin levels were associated with high-risk pattern mammograms.

CONCLUSION

Adiponectin and osteocalcin levels were directly associated with high-risk pattern mammograms in obese postmenopausal women. These results do not support the use of adipokines as biomarkers; nevertheless, the most important factor is to assess the risk through breast density.

Circulating leptin and adiponectin, and breast density in premenopausal Mexican women: the Mexican Teachers' Cohort

PURPOSE

Leptin and adiponectin are produced by the adipose tissue. Mammographic density (MD) is one of the strongest predictors of breast cancer (BC) and is highly influenced by adiposity. How the interplay between MD, obesity, and obesity-related biomarkers influences BC risk, however, is still unknown, especially in premenopausal women, where adiposity seems to be protective for BC. The aim of the present study was to explore the association between circulating leptin, adiponectin, and their ratio, with MD in Mexican premenopausal women who are part of the large Mexican Teachers' Cohort (MTC).

METHODS

A subsample of 2,084 women from the MTC participated in a clinical evaluation. Of them, 574 premenopausal women were randomly selected, from four MD strata. Serum leptin and adiponectin concentrations were measured by immunoassays. Multivariate regression analyses were performed to compare means of MD by quartiles of adipokines and their ratio.

RESULTS

High leptin and leptin/adiponectin ratio levels were significantly associated with lower percentage MD and higher absolute and non-absolute dense tissue areas. High adiponectin levels were significantly associated with lower absolute dense and non-dense tissue areas, but not with percentage MD. After adjustment for BMI, only the associations between percentage MD and absolute non-dense tissue area with leptin remained statistically significant.

CONCLUSIONS

Leptin, adiponectin, and their ratio were associated with MD; however, only the positive association with leptin seemed to be independent from overall obesity.

Dense breast tissue in postmenopausal women is associated with a pro-inflammatory microenvironment in vivo

Inflammation is one of the hallmarks of carcinogenesis. High mammographic density has been associated with increased risk of breast cancer but the mechanisms behind are poorly understood. We evaluated whether breasts with different mammographic densities exhibited differences in the inflammatory microenvironment. Postmenopausal women attending the mammography-screening program were assessed having extreme dense, n = 20, or entirely fatty breasts (nondense), n = 19, on their regular mammograms. Thereafter, the women were invited for magnetic resonance imaging (MRI), microdialysis for the collection of extracellular molecules in situ and a core tissue biopsy for research purposes. On the MRI, lean tissue fraction (LTF) was calculated for a continuous measurement of breast density. LTF confirmed the selection from the mammograms and gave a continuous measurement of breast density. Microdialysis revealed significantly increased extracellular in vivo levels of IL-6, IL-8, vascular endothelial growth factor, and CCL5 in dense breast tissue as compared with nondense breasts. Moreover, the ratio IL-1Ra/IL-1β was decreased in dense breasts. No differences were found in levels of IL-1β, IL-1Ra, CCL2, leptin, adiponectin, or leptin:adiponectin ratio between the two breast tissue types. Significant positive correlations between LTF and the pro-inflammatory cytokines as well as between the cytokines were detected. Stainings of the core biopsies exhibited increased levels of immune cells in dense breast tissue. Our data show that dense breast tissue in postmenopausal women is associated with a pro-inflammatory microenvironment and, if confirmed in a larger cohort, suggests novel targets for prevention therapies for women with dense breast tissue.

Type 2 diabetes and mammographic breast density among underserved women

PURPOSE

We conducted a study of women recruited at Meharry Medical College, a historically black medical school, to investigate the relationship between diabetes and mammographic breast density.

METHODS

A total of 476 women completed in-person interviews, body measurements, and full-field digital mammograms on a Hologic mammography unit from December 2011 to February 2014. Average percent breast density for the left and right breasts combined was estimated using Quantra, an automated algorithm for volumetric assessment of breast tissue. The prevalence of type 2 diabetes was determined by self-report.

RESULTS

After adjustment for confounding variables, the mean percent breast density among premenopausal women with type 2 diabetes [[Formula: see text] 13.8 %, 95 % confidence interval (CI) 11.6-15.9] was nonsignificantly lower than that of women without type 2 diabetes ([Formula: see text] 15.9 %, 95 % CI 15.0-16.8) (p = 0.07); however, there was no association among postmenopausal women. The effect of type 2 diabetes in severely obese women (BMI ≥ 35) appeared to differ by menopausal status with a reduction in mean percent breast density in premenopausal women, but an increase in mean percent breast density in postmenopausal women which could have been due to chance.

CONCLUSIONS

Confirmation of our findings in larger studies may assist in clarifying the role of the insulin signaling breast cancer pathway in women with high breast density.

Circulating adiponectin and breast cancer risk: a systematic review and meta-analysis

BACKGROUND

We conducted a meta-analysis in order to investigate whether circulating adiponectin, an insulin-sensitizing hormone produced by adipocytes, is associated with breast cancer risk.

METHODS

A systematic literature search was performed in PubMed, Medline, EMBASE, ISI Web of Knowledge and the Cochrane Library. The summary relative risk (SRR) was calculated by pooling the different study-specific estimates using the random effect models. Meta-regression, subgroup and sensitivity analyses were carried out to investigate between-study heterogeneity and to test publication bias.

RESULTS

Data from 15 observational studies, published between 2003 and April 2013 for a total of 4249 breast cancer cases, were analysed. The SRR for the 'highest' vs 'lowest' adiponectin levels indicated a 34% reduction in breast cancer risk [95% confidence interval (CI): 13%-50%]. Between-study heterogeneity was not substantial (I(2)=53%). Ten studies were included in the dose-response analysis: the SRR for an increase of 3 µg/ml of adiponectin corresponded to a 5% risk reduction (95% CI: 1%-9%). The comparison between 'highest' and 'lowest' levels of adiponectin showed an inverse association in postmenopausal women (SRR=0.80; 95% CI: 0.63-1.01) and an indication of an inverse relationship in premenopausal women (SRR=0.72, 95% CI: 0.30-1.72). No evidence of publication bias was found.

CONCLUSIONS

Low circulating adiponectin levels are associated with an increased breast cancer risk. However, properly designed studies are needed to confirm the role of adiponectin as breast cancer biomarker, and clinical trials should be performed to identify those interventions that may be effective in modulating adiponectin levels and reducing breast cancer risk.

Plasma leptin levels, LEPR Q223R polymorphism and mammographic breast density: a cross-sectional study

Obesity is associated with breast cancer in post-menopausal women, and breast density is a marker of breast cancer risk. Leptin is produced by the adipose tissue, acts through receptors that are polymorphic in nature, and is considered a cancer growth factor. The relationship between body mass index, leptin, leptin receptors and breast density is not well studied. A cross-sectional analysis in 392 post-menopausal healthy women was conducted; participants provided permission to obtain copies of their most recent screening mammogram. Non-fasting plasma leptin levels were determined using a commercially available leptin ELISA kit. Analysis of the Q223R genotypes of the LEPR gene were performed by PCR followed by restriction fragment length polymorphism analysis using DNA extracted from buffy coat samples. A statistically significant positive relationship was observed between leptin levels and body mass index (p<0.0001); leptin was significantly positively associated with mammography total breast area and non-dense breast area (p<0.0001), while it was inversely associated with percent breast density (p<0.0001). Leptin levels varied across the LEPR Q223R polymorphism, and were higher in women homozygous for the AA variant. Percent breast density decreased across the LEPR Q223R genotype, with lower percent density in women with the AA genotype. When dense area was considered according to quartiles of leptin and stratified by LEPR Q223R, a significant inverse trend between leptin levels and dense breast area was observed only among women with the G/G genotype (p-trend<0.001). After adjustment for possible confounders, leptin levels were significantly inversely associated with percent breast density (p=0.01). A significant interaction between body mass index and leptin levels on percent breast density was observed (p=0.03). These findings suggest that the association between leptin and breast density may vary by LEPR Q223R genotype, and that body mass index and leptin may act in an interactive way in determining breast density.

The tetrad BMI, leptin, leptin/adiponectin (L/A) ratio and CA 15-3 are reliable biomarkers of breast cancer

BACKGROUND

Several studies have reported that leptin levels, the leptin/adiponectin (L/A) ratio and carbohydrate antigen (CA) 15-3 are especially elevated in breast cancer patients with high body mass index (BMI). The purpose of this study was to evaluate BMI, leptin, L/A ratio and CA 15-3 all together as reliable biomarkers for breast cancer.

METHODS

Serum levels of leptin, adiponectin and CA 15-3, as well as anthropometric and biochemical parameters were analysed in 88 female patients who participated in a mammography study. Predictive values of BMI, leptin, L/A ratio and CA 15-3 were determined with a 95% confidence interval.

RESULTS

Women were diagnosed with either breast cancer (n = 40) or benign breast lesions (n = 48). Among anthropometric parameters, age (P ≤ 0.001), weight (P ≤ 0.05) and waist circumference (P ≤ 0.02) were higher in patients with breast cancer than in patients without this pathology. The 75th percentile values for BMI, leptin, L/A ratio and CA 15-3 were 29.24 kg/m(2), 26.65 ng/ml, 2.37 and 18.45 IU, respectively. The suggested odds ratio for breast cancer patients with the values that were above the 75th percentile of the tetrad was 6.7 (0.7505-60.0665 confidence interval).

CONCLUSION

When the four variables were analysed together, a sensitivity of 83.3%, specificity of 80%, positive predictive value of 83.3% and negative predictive value of 80% were obtained. Results indicate that using the 75th percentile set points for BMI, leptin, L/A ratio and CA 15-3 together could offer a reliable approach to determine which women are at high risk for developing breast cancer.

Plasma matrix metalloproteinases and postmenopausal breast cancer risk: a nested case-control study in the Multiethnic Cohort study

The survival of malignant breast cells depends upon the remodeling of the extracellular matrix, including complex interactions with matrix metalloproteinases (MMPs). It has been hypothesized that circulating MMPs may serve as early indicators of breast cancer development in hospital-based case-control studies. A nested case-control study of the association of pre-diagnostic plasma levels of MMPs with the subsequent risk of postmenopausal breast cancer was conducted within the Multiethnic Cohort. During the follow-up period, 713 women with incident invasive breast cancer were identified and individually (1:1) matched to controls. Four types of MMPs (1, 2, 3, and 7) were analyzed by microsphere immunofluorescence assay. Mean plasma levels of MMPs did not differ significantly between cases and controls; nor were there differences in breast cancer risk by MMP level. No difference in the risk of breast cancer by plasma level of the MMPs was found within strata of age, or ethnicity, although MMP-1 levels were positively associated with breast cancer risk in obese women and women by hormone replacement medications (P values for interaction <0.05). Few significant differences in risk by levels of the MMPs were found by any of the clinical variables. Circulating MMPs were not associated with postmenopausal breast cancer risk.

Prognostic effect of circulating adiponectin in a randomized 2 x 2 trial of low-dose tamoxifen and fenretinide in premenopausal women at risk for breast cancer

PURPOSE

Adipokines are linked to obesity and insulin sensitivity and have recently been related to breast cancer risk and prognosis. We investigated the associations of plasma leptin and adiponectin with mammographic density and disease status and assessed their prognostic effect on recurrence-free survival in premenopausal women at risk for breast cancer.

PATIENTS AND METHODS

We measured circulating lipids, insulin-like growth factor 1, glucose, insulin and insulin sensitivity (calculated by homeostasis model assessment [HOMA] index), leptin, adiponectin, and leptin-to-adiponectin ratio in 235 premenopausal women with pT1mic/pT1a breast cancer (n = 21), intraepithelial neoplasia (n = 160), or 5-year Gail risk of 1.3% or greater (n = 54) who participated in a 2 × 2 trial of low-dose tamoxifen, fenretinide, both agents, or placebo over a 2-year period.

RESULTS

At baseline, adiponectin levels were directly associated with mammographic density and HDL cholesterol and negatively associated with leptin, leptin-to-adiponectin ratio, body mass index (BMI), and HOMA index. Median adiponectin levels were lower in affected than in unaffected women (P = .006). After a median of 7.2 years and total of 57 breast neoplastic events, there was a 12% reduction in the risk of breast neoplastic events per unit increase of adiponectin (adjusted hazard ratio, 0.88; 95% CI, 0.81 to 0.96; P = .03). There was no interaction between treatment and adiponectin levels.

CONCLUSION

Low adiponectin levels are associated with a history of prior intraepithelial neoplasia or pT1mic/pT1a breast cancer and higher risk of second breast neoplastic events in premenopausal women. The associations are independent of BMI, mammographic density, and treatment. Our findings support the role of adiponectin as a potential target for premenopausal breast cancer prevention and treatment.

Hormonal mechanisms underlying the relationship between obesity and breast cancer

Given the worldwide epidemic of obesity, it is inevitably an increasingly common comorbidity for women who develop breast cancer; therefore, it is critical to understand its impact on this disease. This review focuses on the influence of obesity on breast cancer development and progression and describes the hormonal factors that may underlie the observations, with particular emphasis on the roles of estrogen, insulin/insulin-like growth factor axis, and adipokines.

Adiponectin and breast cancer

Adiponectin, an adipose tissue-derived hormone, has been studied intensively for the past decade because of its anti-inflammatory, anti-atherogenic, and anti-diabetic properties. Recent advances suggest that adiponectin also plays an important role in the development and progression of various cancers, especially obesity-related cancers. In this review, the authors focus on the potential role of adiponectin in breast cancer, an obesity- and endocrine-associated tumor. Epidemiological studies have shown that plasma adiponectin level is a risk factor for breast cancer in post-menopausal women. Adiponectin and its receptors are expressed on both breast cancer line cells and tumor tissues. Furthermore, exogenous adiponectin has exhibited therapeutic potential in animal models. Underlying mechanisms include the inhibition of cell proliferation and promotion of apoptosis, the regulation of tumorigenic-related factors, and the suppression of angiogenesis. The signaling pathways linking adiponectin with tumorigenesis might provide potential drug targets for the future. However, more convincing evidence is needed to fully elucidate the exact role of adiponectin in breast cancer, since both its beneficial effects and possible mechanisms remain controversial.

Adiponectin and breast cancer

Adiponectin, an adipose tissue-derived hormone, has been studied intensively for the past decade because of its anti-inflammatory, anti-atherogenic, and anti-diabetic properties. Recent advances suggest that adiponectin also plays an important role in the development and progression of various cancers, especially obesity-related cancers. In this review, the authors focus on the potential role of adiponectin in breast cancer, an obesity- and endocrine-associated tumor. Epidemiological studies have shown that plasma adiponectin level is a risk factor for breast cancer in post-menopausal women. Adiponectin and its receptors are expressed on both breast cancer line cells and tumor tissues. Furthermore, exogenous adiponectin has exhibited therapeutic potential in animal models. Underlying mechanisms include the inhibition of cell proliferation and promotion of apoptosis, the regulation of tumorigenic-related factors, and the suppression of angiogenesis. The signaling pathways linking adiponectin with tumorigenesis might provide potential drug targets for the future. However, more convincing evidence is needed to fully elucidate the exact role of adiponectin in breast cancer, since both its beneficial effects and possible mechanisms remain controversial.