Obesity, Leptin and Breast Cancer: Epidemiological Evidence and Proposed Mechanisms

Mendelian randomisation analysis of circulating adipokines and C-reactive protein on breast cancer risk

Circulating adipokines and C-reactive protein (CRP) have been linked to breast cancer risk in observational epidemiological studies. The causal nature of these associations is unclear because of the susceptibility of conventional observational designs to residual confounding, reverse causation and other forms of bias. Mendelian randomisation (MR) uses genetic variants as proxies for risk factors to strengthen causal inference in observational settings. We performed a MR analysis to evaluate the causal relevance of six previously reported circulating adipokines [adiponectin, hepatocyte growth factor (HGF), interleukin-6, leptin receptor, plasminogen activator inhibitor-1 and resistin] and CRP in risk of overall and oestrogen receptor-stratified breast cancer in up to 122,977 cases and 105,974 controls of European ancestry. Genetic instruments were constructed from single-nucleotide polymorphisms robustly (p < 5 × 10-8 ) associated with risk factors in genome-wide association studies. Colocalisation was performed as a sensitivity analysis to examine whether findings reflected shared causal variants or genomic confounding. In MR analyses, there was evidence for an association of HGF with oestrogen receptor-negative cancer (odds ratio per standard deviation increase: 1.17, 95% confidence interval: 1.01-1.35; p = 0.035) but little evidence for associations of other adipokines or CRP with overall or oestrogen receptor-stratified breast cancer. Colocalisation analysis suggested that the association of HGF with oestrogen receptor-negative breast cancer was unlikely to reflect a causal association. Collectively, these findings do not support an important aetiological role of various adipokines or CRP in overall or oestrogen receptor-specific breast cancer risk.

A systematic review of the biological mechanisms linking physical activity and breast cancer

PURPOSE

Epidemiological evidence has shown that leisure-time physical activity and structured exercise before and after breast cancer diagnosis contribute to reducing the risk of breast cancer recurrence and mortality. Thus, in this review, we aimed to summarize the physical activity-dependent regulation of systemic factors to understand the biological and molecular mechanisms involved in the initiation, progression, and survival of breast cancer.

METHODS

We systematically reviewed the studies on 1) the relationship between physical activity and the risk of breast cancer, and 2) various systemic factors induced by physical activity and exercise that are potentially linked to breast cancer outcomes. To perform this literature review, PubMed database was searched using the terms "Physical activity OR exercise" and "breast cancer", until August 5th, 2020; then, we reviewed those articles related to biological mechanisms after examining the resulting search list.

RESULTS

There is strong evidence that physical activity reduces the risk of breast cancer, and the protective effect of physical activity on breast cancer has been achieved by long-term regulation of various circulatory factors, such as sex hormones, metabolic hormones, inflammatory factors, adipokines, and myokines. In addition, physical activity substantially alters wholebody homeostasis by affecting numerous other factors, including plasma metabolites, reactive oxygen species, and microRNAs as well as exosomes and gut microbiota profile, and thereby every cell and organ in the whole body might be ultimately affected by the biological perturbation induced by physical activity and exercise.

CONCLUSION

The understanding of integrative mechanisms will enhance how physical activity can ultimately influence the risk and prognosis of various cancers, including breast cancer. Furthermore, physical activity could be considered an efficacious non-pharmacological therapy, and the promotion of physical activity is probably an effective strategy in primary cancer prevention.

Adipocytokines: Are they the Theory of Everything?

INTRODUCTION

Adipose tissue secretes various bioactive peptides/proteins, immune molecules and inflammatory mediators which are known as adipokines or adipocytokines. Adipokines play important roles in the maintenance of energy homeostasis, appetite, glucose and lipid metabolism, insulin sensitivity, angiogenesis, immunity and inflammation. Enormous number of studies from all over the world proved that adipocytokines are involved in the pathogenesis of diseases affecting nearly all body systems, which raises the question whether we can always blame adipocytokines as the triggering factor of every disease that may hit the body.

OBJECTIVE

Our review targeted the role played by adipocytokines in the pathogenesis of different diseases affecting different body systems including diabetes mellitus, kidney diseases, gynecological diseases, rheumatologic disorders, cancers, Alzheimer's, depression, muscle disorders, liver diseases, cardiovascular and lung diseases.

METHODOLOGY

We cited more than 33 recent literature reviews that discussed the role played by adipocytokines in the pathogenesis of different diseases affecting different body systems.

CONCLUSION

More evidence is being discovered to date about the role played by adipocytokines in more diseases and extra research is needed to explore hidden roles played by adipokine imbalance on disease pathogenesis.

Circulating Levels of Inflammatory and Metabolic Biomarkers and Risk of Esophageal Adenocarcinoma and Barrett Esophagus: Systematic Review and Meta-analysis

Associations between circulating levels of obesity-related biomarkers and risk of esophageal adenocarcinoma and Barrett esophagus have been reported, but the results are inconsistent. A literature search until October 2018 in MEDLINE and EMBASE was performed. Pooled ORs with 95% confidence intervals (CI) were estimated for associations between 13 obesity-related inflammatory and metabolic biomarkers and risk of esophageal adenocarcinoma or Barrett esophagus using random effect meta-analyses. Among 7,641 studies, 19 were eligible for inclusion (12 cross-sectional, two nested case-control, and five cohort studies). Comparing the highest versus lowest categories of circulating biomarker levels, the pooled ORs were increased for leptin (OR, 1.68; 95% CI, 0.95-2.97 for Barrett esophagus), glucose (OR, 1.12; 95% CI, 1.03-1.22 for esophageal adenocarcinoma), insulin (OR, 1.47; 95% CI, 1.06-2.00 for Barrett esophagus), C-reactive protein (CRP; OR, 2.06; 95% CI, 1.28-3.31 for esophageal adenocarcinoma), IL6 (OR, 1.50; 95% CI, 1.03-2.19 for esophageal adenocarcinoma), and soluble TNF receptor 2 (sTNFR-2; OR, 3.16; 95% CI, 1.76-5.65 for esophageal adenocarcinoma). No associations were identified for adiponectin, ghrelin, insulin-like growth factor 1, insulin-like growth factor-binding protein 3, triglycerides, IL8, or TNFα. Higher circulating levels of leptin, glucose, insulin, CRP, IL6, and sTNFR-2 may be associated with an increased risk of esophageal adenocarcinoma or Barrett esophagus. More prospective studies are required to identify biomarkers that can help select high-risk individuals for targeted prevention and early detection.

Fatty Acids and Membrane Lipidomics in Oncology: A Cross-Road of Nutritional, Signaling and Metabolic Pathways

Fatty acids are closely involved in lipid synthesis and metabolism in cancer. Their amount and composition are dependent on dietary supply and tumor microenviroment. Research in this subject highlighted the crucial event of membrane formation, which is regulated by the fatty acids' molecular properties. The growing understanding of the pathways that create the fatty acid pool needed for cell replication is the result of lipidomics studies, also envisaging novel fatty acid biosynthesis and fatty acid-mediated signaling. Fatty acid-driven mechanisms and biological effects in cancer onset, growth and metastasis have been elucidated, recognizing the importance of polyunsaturated molecules and the balance between omega-6 and omega-3 families. Saturated and monounsaturated fatty acids are biomarkers in several types of cancer, and their characterization in cell membranes and exosomes is under development for diagnostic purposes. Desaturase enzymatic activity with unprecedented de novo polyunsaturated fatty acid (PUFA) synthesis is considered the recent breakthrough in this scenario. Together with the link between obesity and cancer, fatty acids open interesting perspectives for biomarker discovery and nutritional strategies to control cancer, also in combination with therapies. All these subjects are described using an integrated approach taking into account biochemical, biological and analytical aspects, delineating innovations in cancer prevention, diagnostics and treatments.

Role of Leptin in Inflammation and Vice Versa

Inflammation is an essential immune response for the maintenance of tissue homeostasis. In a general sense, acute and chronic inflammation are different types of adaptive response that are called into action when other homeostatic mechanisms are insufficient. Although considerable progress has been made in understanding the cellular and molecular events that are involved in the acute inflammatory response to infection and tissue injury, the causes and mechanisms of systemic chronic inflammation are much less known. The pathogenic capacity of this type of inflammation is puzzling and represents a common link of the multifactorial diseases, such as cardiovascular diseases and type 2 diabetes. In recent years, interest has been raised by the discovery of novel mediators of inflammation, such as microRNAs and adipokines, with different effects on target tissues. In the present review, we discuss the data emerged from research of leptin in obesity as an inflammatory mediator sustaining multifactorial diseases and how this knowledge could be instrumental in the design of leptin-based manipulation strategies to help restoration of abnormal immune responses. On the other direction, chronic inflammation, either from autoimmune or infectious diseases, or impaired microbiota (dysbiosis) may impair the leptin response inducing resistance to the weight control, and therefore it may be a cause of obesity. Thus, we are reviewing the published data regarding the role of leptin in inflammation, and the other way around, the role of inflammation on the development of leptin resistance and obesity.

Mammary Adipose Tissue Control of Breast Cancer Progression: Impact of Obesity and Diabetes

Mammary adipose tissue (AT) is necessary for breast epithelium. However, in breast cancer (BC), cell-cell interactions are deregulated as the tumor chronically modifies AT microenvironment. In turn, breast AT evolves to accommodate the tumor, and to participate to its dissemination. Among AT cells, adipocytes and their precursor mesenchymal stem cells (MSCs) play a major role in supporting tumor growth and dissemination. They provide energy supplies and release a plethora of factors involved in cancer aggressiveness. Here, we discuss the main molecular mechanisms underlining the interplay between adipose (adipocytes and MSCs) and BC cells. Following close interactions with BC cells, adipocytes lose lipids and change morphology and secretory patterns. MSCs also play a major role in cancer progression. While bone marrow MSCs are recruited by BC cells and participate in metastatic process, mammary AT-MSCs exert a local action by increasing the release of cytokines, growth factors and extracellular matrix components and become principal actors in cancer progression. Common systemic metabolic diseases, including obesity and diabetes, further modify the interplay between AT and BC. Indeed, metabolic perturbations are accompanied by well-known alterations of AT functions, which might contribute to worsen cancer phenotype. Here, we highlight how metabolic alterations locally affect mammary AT and interfere with the molecular mechanisms of bidirectional communication between adipose and cancer cells.

Knockdown of Leptin Receptor Affects Macrophage Phenotype in the Tumor Microenvironment Inhibiting Breast Cancer Growth and Progression

Aberrant leptin (Ob) signaling, a hallmark of obesity, has been recognized to influence breast cancer (BC) biology within the tumor microenvironment (TME). Here, we evaluated the impact of leptin receptor (ObR) knockdown in affecting BC phenotype and in mediating the interaction between tumor cells and macrophages, the most abundant immune cells within the TME. The stable knockdown of ObR (ObR sh) in ERα-positive and ERα-negative BC cells turned the tumor phenotype into a less aggressive one, as evidenced by in vitro and in vivo models. In xenograft tumors and in co-culture experiments between circulating monocytes and BC cells, the absence of ObR reduced the recruitment of macrophages, and also affected their cytokine mRNA expression profile. This was associated with a decreased expression and secretion of monocyte chemoattractant protein-1 in ObR sh clones. The loss of Ob/ObR signaling modulated the immunosuppressive TME, as shown by a reduced expression of programmed death ligand 1/programmed cell death protein 1/arginase 1. In addition, we observed increased phagocytic activity of macrophages compared to control Sh clones in the presence of ObR sh-derived conditioned medium. Our findings, addressing an innovative role of ObR in modulating immune TME, may open new avenues to improve BC patient health care.

Leptin Promotes Prostate Cancer Proliferation and Migration by Stimulating STAT3 Pathway

To better understand the link between obesity and prostate cancer (PC) aggressiveness, we investigate the role of leptin, an obesity associated adipokine, and its receptor (Ob-R) in PC cells migration. The migration assay (Wound-healing) was used to study the leptin impact on DU-145 and PC3 cells lines. STAT3 activation was performed by Western Blot. E-cadherin expression was studied using fluorescence microscopy and Ob-R expression in PC and benign prostatic Hyperplasia (BPH) biopsies was assessed by RT-PCR. In this study we demonstrate that high dose of leptin promotes PC cells migration and EMT transition via the stimulation of STAT3 pathway. In addition, we report that although Ob-R mRNA is expressed by ADK and BPH resections biopsies, significant higher levels were observed for ADK patients. Finally, we found a positive association between Ob-R mRNA expression and worse PC prognosis. A better understanding of the molecular processes of leptin signaling is crucial for identifying appropriate approaches for treatment of obesity-related PC patients.

Postdiagnosis weight change is associated with poorer survival in breast cancer survivors: A prospective population-based patient cohort study

More women are surviving after breast cancer due to early detection and modern treatment strategies. Body weight also influences survival. We aimed to characterize associations between postdiagnosis weight change and prognosis in postmenopausal long-term breast cancer survivors. We used data from a prospective population-based patient cohort study (MARIE) conducted in two geographical regions of Germany. Breast cancer patients diagnosed 50 to 74 years of age with an incident invasive breast cancer or in situ tumor were recruited from 2002 to 2005 and followed up until June 2015. Baseline weight was ascertained at an in-person interview at recruitment and follow-up weight was ascertained by telephone interview in 2009. Delayed entry Cox proportional hazards regression was used to assess associations between relative weight change and all-cause mortality, breast cancer mortality, and recurrence-free survival. In total, 2216 patients were included. Compared to weight maintenance (within 5%), weight loss >10% increased risk of all-cause mortality (HR 2.50, 95% CI 1.61, 3.88), breast cancer mortality (HR 3.07, 95% CI 1.69, 5.60) and less so of recurrence-free survival (HR 1.43, 95% CI 0.87, 2.36). Large weight gain of >10% also increased all-cause mortality (HR 1.64, 95% CI 1.02, 2.62) and breast cancer mortality (HR 2.25, 95% CI 1.25, 4.04). Weight maintenance for up to 5 years in long-term breast cancer survivors may help improve survival and prognosis. Postdiagnosis fluctuations in body weight of greater than 10% may lead to increased mortality. Survivors should be recommended to avoid large deviations in body weight from diagnosis onwards to maintain health and prolong life.

Obesity and Breast Cancer: A Case of Inflamed Adipose Tissue

Obesity is associated with an increased risk of estrogen receptor-positive breast cancer in postmenopausal women and a worse prognosis for all major breast cancer subtypes regardless of menopausal status. While the link between obesity and the pathogenesis of breast cancer is clear, the molecular mechanism of this association is not completely understood due to the complexity of both obesity and breast cancer. The aim of this review is to highlight the association between obesity and breast cancer and discuss the literature, which indicates that this association is due to chronic adipose tissue inflammation. We will discuss the epidemiological data for the association between breast cancer incidence and progression as well as the potential molecular mechanisms for this association. We will focus on the role of inflammation within the adipose tissue during the pathogenesis of breast cancer. A better understanding of how obesity and adipose tissue inflammation affects the pathogenesis of breast cancer will lead to new strategies to reduce breast cancer risk and improve patient outcomes for obese patients.

Leptin and Notch Signaling Cooperate in Sustaining Glioblastoma Multiforme Progression

Glioblastoma multiforme (GBM) is the most malignant form of glioma, which represents one of the commonly occurring tumors of the central nervous system. Despite the continuous development of new clinical therapies against this malignancy, it still remains a deadly disease with very poor prognosis. Here, we demonstrated the existence of a biologically active interaction between leptin and Notch signaling pathways that sustains GBM development and progression. We found that the expression of leptin and its receptors was significantly higher in human glioblastoma cells, U-87 MG and T98G, than in a normal human glial cell line, SVG p12, and that activation of leptin signaling induced growth and motility in GBM cells. Interestingly, flow cytometry and real-time RT-PCR assays revealed that GBM cells, grown as neurospheres, displayed stem cell-like properties (CD133+) along with an enhanced expression of leptin receptors. Leptin treatment significantly increased the neurosphere forming efficiency, self-renewal capacity, and mRNA expression levels of the stemness markers CD133, Nestin, SOX2, and GFAP. Mechanistically, we evidenced a leptin-mediated upregulation of Notch 1 receptor and the activation of its downstream effectors and target molecules. Leptin-induced effects on U-87 MG and T98G cells were abrogated by the selective leptin antagonist, the peptide LDFI (Leu-Asp-Phe-Ile), as well as by the specific Notch signaling inhibitor, GSI (Gamma Secretase Inhibitor) and in the presence of a dominant-negative of mastermind-like-1. Overall, these findings demonstrate, for the first time, a functional interaction between leptin and Notch signaling in GBM, highlighting leptin/Notch crosstalk as a potential novel therapeutic target for GBM treatment.

Pre-Operative Combination of Normal BMI with Elevated YKL-40 and Leptin but Lower Adiponectin Level Is Linked to a Higher Risk of Breast Cancer Relapse: A Report of Four-Year Follow-Up Study

Adipokines are powerful agents involved in the development of obesity-dependent cancers. This prospective study aimed to investigate the association between pre-treatment body mass index (BMI) and serum YKL-40, leptin, and adiponectin concentrations as well as the plasma activity of tissue factor (TF) and the future prognosis of early, non-metastatic breast cancer (BrC) subjects. The serum levels of YKL-40, leptin, and adiponectin as well as plasma TF activity, anthropometric parameters, and clinicopathological parameters were analysed in 81 treatment-naïve females with invasive BrC. The predictive value of YKL-40, BMI, leptin, adiponectin, and TF was determined with a 95% confidence interval (CI). Kaplan–Meier plots and log-rank and F Cox tests were used to determine the clinical outcomes of progression-free survival (PFS). The median follow-up duration was 44 months with complete follow-up for the first event. Follow-up revealed a significantly higher incidence of disease relapse in BrC patients with a high baseline concentration of YKL-40 (22.22%) and TF activity (21.43%). Body mass index was an independent predictor of survival, with women who were overweight/obese being less prone to relapse (hazard ratio (HR): 0.75; 95% CI: 0.59 to 0.95). The recurrence rates for normal-weight BrC cases was 21.05% versus 7.14% for their overweight counterparts. The receiver operating characteristic analysis showed the strong ability of the analysed biomarkers to predict disease progression, with an area under the receiver operating characteristics (ROC) curve of 0.84 (95% CI, 0.823 to 0.931). In a prospective cohort of invasive BrC patients, overweight/obesity was associated with improved future outcomes. The combination of a normal BMI with high leptin and low adiponectin levels and high TF activity was associated with an increased risk of recurrence and decreased survival.

Leptin decreases BC cell susceptibility to NK lysis via PGC1A pathway

Large prospective studies established a link between obesity and breast cancer (BC) development. Yet, the mechanisms underlying this association are not fully understood. Among the diverse adipocytokine secreted by hypertrophic adipose tissue, leptin is emerging as a key candidate molecule linking obesity and cancer, since it promotes proliferation and invasiveness of tumors. However, the potential implication of leptin on tumor escape mechanisms remains unknown. This study aims to explore the effect of leptin on tumor resistance to NK lysis and the underlying mechanism. We found that leptin promotes both BC resistance to NK92-mediated lysis and β oxidation on MCF-7, by the up-regulation of a master regulator of mitochondrial biogenesis, the peroxisome proliferator activated receptor coactivator-1 α (PGC1A). Using adenoviral approaches, we show that acute elevation of PGC1A enhances the fatty acid oxidation pathway and decreases the susceptibility of BC cells to NK92-mediated lysis. Importantly, we identified the involvement of PGC1A and leptin in the regulation of hypoxia inducible factor-1 alpha (HIF1A) expression by tumor cells. We further demonstrate that basal BC cells MDA-MB-231 and BT-20 exhibit an increased PGC1A mRNA level and an enhanced oxidative phosphorylation activity; in comparison with luminal BC cells MCF7 and MDA-361, which are associated with more resistance NK92 lysis. Altogether, our results demonstrate for the first time how leptin could promote tumor resistance to immune attacks. Reagents blocking leptin or PGC1A activity might aid in developing new therapeutic strategies to limit tumor development in obese BC patients.

Linking Obesity with Colorectal Cancer: Epidemiology and Mechanistic Insights

The incidence of obesity and colorectal cancer (CRC) has risen rapidly in recent decades. More than 650 million obese and 2 billion overweight individuals are currently living in the world. CRC is the third most common cancer. Obesity is regarded as one of the key environmental risk factors for the pathogenesis of CRC. In the present review, we mainly focus on the epidemiology of obesity and CRC in the world, the United States, and China. We also summarize the molecular mechanisms linking obesity to CRC in different aspects, including nutriology, adipokines and hormones, inflammation, gut microbiota, and bile acids. The unmet medical needs for obesity-related CRC are still remarkable. Understanding the molecular basis of these associations will help develop novel therapeutic targets and approaches for the treatment of obesity-related CRC.

Leptin Signaling Affects Survival and Chemoresistance of Estrogen Receptor Negative Breast Cancer

Estrogen-receptor-negative breast cancer (BCER-) is mainly treated with chemotherapeutics. Leptin signaling can influence BCER- progression, but its effects on patient survival and chemoresistance are not well understood. We hypothesize that leptin signaling decreases the survival of BCER- patients by, in part, inducing the expression of chemoresistance-related genes. The correlation of expression of leptin receptor (OBR), leptin-targeted genes (CDK8, NANOG, and RBP-Jk), and breast cancer (BC) patient survival was determined from The Cancer Genome Atlas (TCGA) mRNA data. Leptin-induced expression of proliferation and chemoresistance-related molecules was investigated in triple-negative BC (TNBC) cells that respond differently to chemotherapeutics. Leptin-induced gene expression in TNBC was analyzed by RNA-Seq. The specificity of leptin effects was assessed using OBR inhibitors (shRNA and peptides). The results show that OBR and leptin-targeted gene expression are associated with lower survival of BCER- patients. Importantly, the co-expression of these genes was also associated with chemotherapy failure. Leptin signaling increased the expression of tumorigenesis and chemoresistance-related genes (ABCB1, WNT4, ADHFE1, TBC1D3, LL22NC03, RDH5, and ITGB3) and impaired chemotherapeutic effects in TNBC cells. OBR inhibition re-sensitized TNBC to chemotherapeutics. In conclusion, the co-expression of OBR and leptin-targeted genes may be used as a predictor of survival and drug resistance of BCER- patients. Targeting OBR signaling could improve chemotherapeutic efficacy.

Skin carotenoids are inversely associated with adiposity in breast cancer survivors

Carotenoids are antioxidants which may mitigate some of the adverse effects of obesity, a condition associated with poor outcomes in breast cancer patients. We hypothesized that baseline skin carotenoids would be inversely associated with adiposity in breast cancer survivors and would increase with weight loss. Skin carotenoid score (SCS) was assessed by resonance Raman spectroscopy in breast cancer survivors (body mass index ≥25 kg/m²) enrolled in a 6-month randomized controlled weight loss trial (n = 47). Measurements included total body fat using dual-energy X-ray absorptiometry, height, weight, waist and hip circumference, dietary intake, and serum biomarkers. Associations between SCS, adiposity measures, and serum biomarkers were assessed at baseline, as was the change in SCS from baseline to 6 months, in the intervention and usual care groups. At baseline, SCS was inversely correlated with all adiposity measures (P ≤ .05). In multivariate analyses, baseline percent body fat had the strongest association with baseline SCS (partial R²= 0.20). Baseline SCS was significantly inversely associated with log C-reactive protein levels (regression coefficient β ± SE: -0.051± 0.019; P = .011) and log leptin (β ± SE: -0.019± 0.009; P = .046), but the associations were no longer significant after adjustment for adiposity. Over the 6-month study, the intervention group had a 17.6% increase in SCS compared to a 1.5% decrease in the usual care group (P = .28). In our study of overweight and obese breast cancer survivors, dual-energy X-ray absorptiometry-measured body fat explained a large portion of the variation in skin carotenoids at baseline, suggesting a stronger association than that previously seen in studies using less accurate measures of adiposity.

Novel insights into adiponectin action in breast cancer: Evidence of its mechanistic effects mediated by ERα expression

This review describes the multifaceted effects of adiponectin on breast cancer cell signalling, tumour metabolism, and microenvironment. It is largely documented that low adiponectin levels are associated with an increased risk of breast cancer. However, it needs to be still clarified what are the extents of the decrease of local/intra-tumoural adiponectin concentrations, which promote breast tumour malignancy. Most of the anti-proliferative and pro-apoptotic effects induced by adiponectin have been obtained in breast cancer cells not expressing estrogen receptor alpha (ERα). Here, we will highlight recent findings demonstrating the mechanistic effects through which adiponectin is able to fuel genomic and non-genomic estrogen signalling, inhibiting LKB1/AMPK/mTOR/S6K pathway and switching energy balance. Therefore, it emerges that the reduced adiponectin levels in patients with obesity work to sustain tumour growth and progression in ERα-positive breast cancer cells. All this may contribute to remove the misleading paradigm that adiponectin univocally inhibits breast cancer cell growth and progression independently on ERα status. The latter concept, here clearly provided by pre-clinical studies, may have translational relevance adopting adiponectin as a potential therapeutic tool. Indeed, the interfering role of ERα on adiponectin action addresses how a separate assessment of adiponectin treatment needs to be considered in novel therapeutic strategies for ERα-positive and ERα-negative breast cancer.

Impact of Weight Loss on the Total Antioxidant/Oxidant Potential in Patients with Morbid Obesity-A Longitudinal Study

The assessment of total antioxidant activity seems to have a higher diagnostic value than the evaluation of individual antioxidants separately. Therefore, this is the first study to assess the total antioxidant/oxidant status in morbidly obese patients undergoing bariatric surgery. The study involved 60 patients with Class 3 obesity (BMI > 40 kg/m²) divided into two equal subgroups: morbidly obese patients without and with metabolic syndrome. The analyses were performed in plasma samples collected before surgery as well as 1, 3, 6, and 12 months after a laparoscopic sleeve gastrectomy. Total antioxidant capacity (TAC), ferric-reducing antioxidant power (FRAP), DPPH (2,2′-diphenyl-1-picrylhydrazyl) radical assay, and total oxidant status (TOS) were significantly higher before surgery (as compared to the healthy controls, n = 60) and generally decreased after bariatric treatment. Interestingly, all assessed biomarkers correlated positively with uric acid content. However, the total antioxidant/oxidant potential did not differ between obese patients without metabolic syndrome and those with both obesity and metabolic syndrome. Only DPPH differentiated the two subgroups (p < 0.0001; AUC 0.8) with 73% sensitivity and 77% specificity. Plasma TAC correlated positively with body mass index, waist–hip ratio, serum insulin, and uric acid. Therefore, TAC seems to be the best biomarker to assess the antioxidant status of obese patients.

IGF-1 Interacted With Obesity in Prognosis Prediction in HER2-Positive Breast Cancer Patients

Purpose: Dysmetabolism and high circulating insulin-like growth factor 1 (IGF-1) would increase breast cancer risk, but its association with survival in HER2+ breast cancer patients has not been well-studied. Herein, we aim to evaluate the prognostic value of IGF-1 and metabolic abnormalities in HER2+ population.

Patients and Methods: HER2+ breast cancer patients treated in Ruijin Hospital between November 2012 and June 2017 were retrospectively analyzed. Median value of circulating IGF-1 was adopted to classify low or high IGF-1 group. Metabolic syndrome (MetS) was defined using AHA/NHLBI criteria. Overweight was defined by body mass index (BMI) ≥ 24.0 kg/m² in Chinese population.

Results: Overall, 679 patients were included and 209 had synchronous MetS. High IGF-1 level was more common in pre/peri-menopausal women (P < 0.001) and high IGFBP-3 patients (P < 0.001). After a median follow-up of 36 months, 52 patients had disease recurrences. IGF-1 level was not associated with recurrence-free survival (RFS, P = 0.620) in the whole population. However, exploratory subgroup analysis found that BMI and IGF-1 interacted in predicting RFS (P = 0.009). For non-overweight patients, high IGF-1 showed a superior 4-years RFS (91.1 vs. 85.0%; HR 0.53, 95% CI 0.27–1.00, P = 0.049) compared with patients with low IGF-1 level. In contrast, for overweight patients, high IGF-1 was associated with an impaired 4-years RFS (88.3 vs. 95.7%, HR 3.20, 95% CI 1.00–10.21, P = 0.038). Furthermore, high IGF-1 level was independently associated with better OS in the whole (HR 0.26, 95% CI 0.08–0.82, P = 0.044) as well as non-overweight population (HR 0.15, 95% CI 0.03–0.68, P = 0.005).

Conclusions: IGF-1 level was not associated with RFS in HER2+ breast cancer patients. However, IGF-1 and BMI had significant interaction in disease outcome prediction in HER2+ patients. High IGF-1 was protective in non-overweight patients, but risk factor for those overweight, which deserves further evaluation.

Life style factors, tumor cell plasticity and cancer stem cells

Cancers are heterogeneous tissues and a layer of heterogeneity is determined by the presence of cells showing stemness traits, known as cancer stem cells (CSCs). Evidence indicates that CSCs are important players in tumor development, progression and relapse. Oncogenic transformation of normal stem cells can give rise to CSCs, but CSCs can also originate from de-differentiation of bulk tumor cells. Thus, factors promoting the increase of normal stem cell pools or stimulating the acquisition of stemness features by tumor cells can have serious consequences on cancer origin and progression. In this review, we will first give an overview of the CSC model of cancer development and we will then discuss the role of life style factors, such as high caloric diet, alcohol drinking and smoking, on the widening of stem cell pools and the induction of CSC features in tumors. Finally, we will discuss some healthy life style factors that can help to prevent cancer.

History of Diabetes Mellitus and Risk of Breast Cancer in Asian Women: A Meta-Epidemiological Analysis of Population-Based Cohort Studies

Objectives

Previous quantitative systematic reviews conducting subgroup analyses by race have reported that the association between diabetes and breast cancer in Asian women was inconclusive. The aim of this meta-epidemiological study (MES) was to evaluate this association from additional population-based cohort studies.

Methods

The potential subjects of this MES were six Asian cohort studies selected by previous systematic reviews. Additional reports were found from the selected articles using citation discovery tools. The study with the longest follow-up period was selected among prospective studies of the same cohorts. A summary relative risk (sRR) and its 95% confidence intervals (CI) were calculated using random effect models.

Results

Four cohort studies on Asian women were finally selected. The participants were from the women population of Korea, Japan, China, and Taiwan and included a total of 1,448,254 women. The sRR (95% CI) (I-squared value) was 1.20 (0.98–1.46) (63.1%).

Conclusions

This MES found that the history of diabetes mellitus was not associated with the risk of breast cancer in Asian women. As breast cancer in this population develops at a younger age, additional cohort studies are necessary to conduct a subgroup analysis by menopausal status at diagnosis of breast cancer in Asian women.

Leptin Signaling Contributes to Aromatase Inhibitor Resistant Breast Cancer Cell Growth and Activation of Macrophages

Obesity represents a risk factor for breast cancer development and therapy resistance, but the molecular players underling these links are unclear. Here, we identify a role for the obesity-cytokine leptin in sustaining aromatase inhibitor (AI) resistant growth and progression in breast cancer. Using as experimental models MCF-7 breast cancer cells surviving long-term treatment with the AI anastrozole (AnaR) and Ana-sensitive counterparts, we found that AnaR cells expressed higher levels of leptin and its receptors (ObR) along with a constitutive activation of downstream effectors. Accordingly, leptin signaling inhibition reduced only AnaR cell growth and motility, highlighting the existence of an autocrine loop in mechanisms governing drug-resistant phenotypes. In agreement with ObR overexpression, increasing doses of leptin were able to stimulate to a greater extent growth and migration in AnaR than sensitive cells. Moreover, leptin contributed to enhanced crosstalk between AnaR cells and macrophages within the tumor microenvironment. Indeed, AnaR, through leptin secretion, modulated macrophage profiles and increased macrophage motility through CXCR4 signaling, as evidenced by RNA-sequencing, real-time PCR, and immunoblotting. Reciprocally, activated macrophages increased AnaR cell growth and motility in coculture systems. In conclusion, acquired AI resistance is accompanied by the development of a leptin-driven phenotype, highlighting the potential clinical benefit of targeting this cytokine network in hormone-resistant breast cancers, especially in obese women.

A Longitudinal Study of the Antioxidant Barrier and Oxidative Stress in Morbidly Obese Patients after Bariatric Surgery. Does the Metabolic Syndrome Affect the Redox Homeostasis of Obese People?

This is the first study to evaluate both the antioxidant barrier, glutathione metabolism, and oxidative damage to proteins and lipids in morbidly obese patients undergoing bariatric treatment. The study included 65 patients with class 3 obesity divided into two subgroups: morbidly obese patients without metabolic syndrome (OB) and obese patients with metabolic syndrome (OB + MS). Blood samples were collected before surgery as well as one, three, six, and twelve months after the bariatric treatment. Superoxide dismutase and reduced glutathione (GSH) were significantly decreased, whereas glutathione reductase and uric acid were enhanced in morbidly obese patients before bariatric surgery as compared to lean control. Moreover, in the OB group, we observed the increase of superoxide dismutase (SOD) and the decrease of uric acid (UA) after the bariatric treatment; however, these changes were not observed in the OB + MS group. The oxidative damage to proteins (advanced glycation end products, AGE; advanced oxidation protein products, AOPP) and lipids (8-isoprostanes, 8-isop; 4-hydroxynoneal) was higher in OB as well as OB + MS patients. We noticed that AGE and AOPP levels diminished after the bariatric treatment, whereas redox status (ratio of GSH to oxidized glutathione) was still reduced in the OB + MS group. Summarizing, morbid obesity is associated with disturbances in the antioxidant barrier and enhanced oxidative damage to proteins and lipids. Although bariatric surgery improves redox homeostasis in obese patients, those with metabolic syndrome show a continuous decrease in the antioxidant status. In patients undergoing bariatric treatment, antioxidant supplementation may be considered.

MTHFR, XRCC1 and OGG1 genetic polymorphisms in breast cancer: a case-control study in a population from North Sardinia

BACKGROUND

Despite conflicting results, considerable evidence suggests the association between single nucleotide polymorphisms in MTHFR, XRCC1 and OGG1 genes and, risk of developing breast cancer. Here a case-control study is reported, including 135 breat cancer patients and 112 healthy women, all representative of Northern Sardinian population.

METHODS

Polymerase chain reaction/restriction fragment length polymorphism method was used to determine the genotypes of five polymorphisms: MTHFR C677T (rs1801133) and A1298C (rs1801131), XRCC1 Arg194Trp (rs1799782) and Arg399Gln (rs25487) and OGG1 Ser326Cys (rs1052133). Allelic, genotypic and haplotype association analyses with disease risk and clinicopathological parameters were performed.

RESULTS

A nominally significant association with breast cancer risk was observed for MTHFR C677T polymorphism heterozygous genotype in the codominant model (OR: 0.57, 95% CI: 0.32-1.00, p = 0.049) and for Cys/Cys genotype of the OGG1 Ser326Cys polymorphism in the recessive model (OR: 0.23, 95% CI: 0.05-1.11, p = 0.0465). No significant differences were found at genotype-level for A1298C polymorphism of the MTHFR gene and Arg194Trp and Arg399Gln of the XRCC1 gene. Furthermore, the OGG1 and XRCC1 rs25487 polymorphisms were nominally associated with PgR, Her2 status and with sporadic breast cancer, respectively.

CONCLUSIONS

Based on genetic characteristics of individuals included in this study, results suggest that MTHFR CT and OGG1 Cys/Cys genotypes have a protective effect that may have an influence on breast cancer risk in a representative Northern Sardinian population.

Impact of BMI for clinical outcomes in Japanese breast cancer patients

OBJECTIVE

The relationship between the body mass index (BMI) at the time of breast cancer diagnosis and the prognosis of breast cancer patients has not yet been clarified. We investigated the impact of obesity for clinical outcomes in Japanese breast cancer patients.

METHODS

Women with primary breast cancer operated between 2002 and 2014 were identified. All patients are categorized into four groups according to BMI. The range of BMI is <18.5 kg/m2, from 18.5 to 24.9 kg/m2, 25 to 29.9 kg/m2, >30 kg/m2 in underweight, normal, overweight and obesity groups, respectively. The correlation between BMI and overall survival (OS), breast cancer-specific survival (BCSS) and disease-free survival (DFS) were statistically analyzed.

RESULTS

From the database of our institution, we identified 3223 patients. The median follow-up period was 57 months (1-149). We categorized 2257 (70.0%), 318 (9.9%), 545 (16.9%) and 103 (3.2%) patients into normal, underweight, overweight obesity groups respectively. There were189 patients (5.9%) deaths due to breast cancer recurrence (137 patients) and other disease (52 patients). Obesity groups was significantly high compared with normal groups for OS (adjusted HR, 2.43; 95% CI, 1.38-4.28; P < 0.001), BCSS (adjusted HR, 2.73; 95% CI, 1.15-6.44; P = 0.02) and DFS (adjusted HR, 1.83; 95% CI, 1.11-3.02; P = 0.017) by multivariate analysis. Especially, OS (adjusted HR, 4.87; 95% CI, 2.15-11.04; P < 0.001), BCSS (adjusted HR, 4.51; 95% CI, 1.52-13.34; P < 0.001) and DFS (adjusted HR, 4.87; 95% CI, 1.02-4.89; P = 0.04) were statistically insignificant in postmenopausal ER-positive breast cancer patients.

CONCLUSION

Obesity might be risk factor for OS, BCSS and DFS, especially postmenopausal ER-positive women.

Globular Adiponectin Inhibits Breast Cancer Cell Growth through Modulation of Inflammasome Activation: Critical Role of Sestrin2 and AMPK Signaling

Adiponectin, an adipokine predominantly derived from adipose tissue, exhibits potent antitumor properties in breast cancer cells. However, its mechanisms of action remain elusive. Inflammasomes—intracellular multimeric protein complexes—modulate cancer cell growth in a complicated manner, as well as playing a role in the innate immune system. Herein, we examined the potential role of inflammasomes in the antitumor activity of adiponectin and found that globular adiponectin (gAcrp) significantly suppressed inflammasomes activation in breast cancer cells both in vitro and in vivo conditions, as determined by decreased expression of inflammasomes components, including NOD-like receptor pyrin domain-containing protein 3 (NLRP3) and the apoptosis-associated speck-like protein containing a CARD (ASC), and inhibition of interleukin-1β and caspase-1 activation. Treatment with pharmacological inhibitors of inflammasomes caused decrease in cell viability, apoptosis induction, and G0/G1 cell cycle arrest, suggesting that inflammasomes activation is implicated in the growth of breast cancer cells. In addition, treatment with gAcrp generated essentially similar results to those of inflammasomes inhibitors, further indicating that suppression of breast cancer cell growth by gAcrp is mediated via modulation of inflammasomes. Mechanistically, gAcrp suppressed inflammasomes activation through sestrin2 (SESN2) induction, liver kinase B1 (LKB-1)-dependent AMP-activated protein kinase (AMPK) phosphorylation, and alleviation of endoplasmic reticulum (ER) stress. Taken together, these results demonstrate that gAcrp inhibits growth of breast cancer cells by suppressing inflammasomes activation, at least in part, via SESN2 induction and AMPK activation-dependent mechanisms.

Leptin Signaling in Liver Tissue of a Transgenic Breast Cancer Mouse Model

Leptin, an adipocytokine, is secreted from various tissues including the liver. The roles of both leptin and leptin receptor (ObR) in numerous pathophysiological conditions including mammary tumor (MT) development have been reported. However, the roles of leptin signaling-related proteins in the liver have not been reported previously in MT development. The objective of this study was to examine the expression levels of leptin and ObR in liver tissue of a transgenic breast cancer mouse model to investigate whether the roles of leptin in MT development are systemic or local. MMTV-TGF-α transgenic female mice were fed ad-libitum from week 10 up to week 74. Protein expression levels of leptin and ObR were measured in liver tissues of 74-week-old MMTV-TGF-α mice with and without MT by western blot. Serum leptin and insulin levels were measured using a enzyme-linked immunosorbent assay. Protein expression levels of leptin and ObR were similar in mice with MT compared to the ones without MT. Serum leptin and insulin levels were also not significantly different between the two groups. These results indicate that the effects of leptin signaling in MT development might be important at a local tissue level, such as mammary fat pad, and not as important at a systemic level.

Linkage Between Obesity Leptin and Breast Cancer

Many cancers might be influenced by obesity, including breast cancer, the leading cause of cancer death among women. Obesity is a complex state associated with multiple physiological and molecular changes capable of modulating the behavior of breast tumor cells and the surrounding microenvironment. This review discussed the inverse association between obesity and breast cancer among premenopausal breast cancer females and the positive association among postmenopausal. Four mechanisms may link obesity and breast cancer including leptin and leptin receptor expression, adipose chronic inflammation, sex hormone alternation, and insulin and insulinlike growth factor 1 (IGF-1) signaling. Leptin has been involved in breast cancer initiation, development, and progression through signaling transduction network. Leptin functions are strengthened through cross talk with multiple oncogenes, cytokines, and growth factors. Adipose chronic inflammation promotes cancer growth and angiogenesis and modifies the immune responses. A pro-inflammatory microenvironment at tumor site promotes cytokines and pro-inflammatory mediators adjacent to the tumor. Leptin stimulates pro-inflammatory cytokines and promotes T-helper 1 responses. Obesity is common of chronic inflammation. In obese patients, white adipose tissue (WAT) will promote pro-inflammatory mediators that will encourage tumor growth and WAT inflammation. Sex hormone alternation of estrogens is associated with increased risk for hormone-sensitive breast cancers. Estrogens cause tumorigenesis by its effect on signaling pathways that lead to DNA damage, stimulation angiogenesis, mutagenesis, and cell proliferation. In postmenopausal females, and due to termination of ovarian function, estrogens were produced extra gonadally, mainly in peripheral adipose tissues where adrenal-produced androgen precursors are converted to estrogens. Active estradiol leads to breast cancer development by binding to ERα, which is modified by receptor’s interaction of various signal transduction pathways. Hyperinsulinemia and IGF-1 activate the MAPK and PI3K pathways, leading to cancer-promoting effects. Cross talk between insulin/IGF and estrogen signaling pathways promotes hormone-sensitive breast cancer development. Hyperinsulinemia is a risk factor for breast cancer that explains the obesity-breast cancer association. Controlling IGF-1 level and targeting IGF-1 receptors among different breast cancer subtypes may be useful for breast cancer treatment. This review discussed several leptin signaling pathways, highlighting the potential advantage of targeting leptin as a potential target of the novel therapeutic strategies for breast cancer treatment.

Interfering Role of ERα on Adiponectin Action in Breast Cancer

Obesity is characterized by an excess of adipose tissue, due to adipocyte hypertrophy and hyperplasia. Adipose tissue is an endocrine organ producing many bioactive molecules, called adipokines. During obesity, dysfunctional adipocytes alter adipokine secretion, contributing to pathophysiology of obesity-associated diseases, including metabolic syndrome, type 2-diabetes, cardiovascular diseases and many types of malignancies. Circulating adiponectin levels are inversely correlated with BMI, thus adiponectin concentrations are lower in obese than normal-weight subjects. Many clinical investigations highlight that low adiponectin levels represent a serious risk factor in breast carcinogenesis, and are associated with the development of more aggressive phenotype. A large-scale meta-analysis suggests that BMI was positively associated with breast cancer mortality in women with ERα-positive disease, regardless menopausal status. This suggests the importance of estrogen signaling contribution in breast tumorigenesis of obese patients. It has been largely demonstrated that adiponectin exerts a protective role in ERα-negative cells, promoting anti-proliferative and pro-apoptotic effects, while controversial data have been reported in ERα-positive cells. Indeed, emerging data provide evidences that adiponectin in obese patients behave as growth factor in ERα-positive breast cancer cells. This addresses how ERα signaling interference may enhance the potential inhibitory threshold of adiponectin in ERα-positive cells. Thus, we may reasonably speculate that the relatively low adiponectin concentrations could be still not adequate to elicit, in ERα-positive breast cancer cells, the same inhibitory effects observed in ERα-negative cells. In the present review we will focus on the molecular mechanisms through which adiponectin affects breast cancer cell behavior in relationship to ERα expression.

The Role of Adipokines in Breast Cancer: Current Evidence and Perspectives

PURPOSE

The current review shows evidence for the role of adipokines in breast cancer (BC) pathogenesis summarizing the mechanisms underlying the association between adipokines and breast malignancy. Special emphasis is given also on intriguing insights into the relationship between obesity and BC as well as on the role of novel adipokines in BC development.

RECENT FINDINGS

Recent evidence has underscored the role of the triad of obesity, insulin resistance, and adipokines in postmenopausal BC. Adipokines exert independent and joint effects on activation of major intracellular signal networks implicated in BC cell proliferation, growth, survival, invasion, and metastasis, particularly in the context of obesity, considered a systemic endocrine dysfunction characterized by chronic inflammation. To date, more than 10 adipokines have been linked to BC, and this catalog is continuously increasing. The majority of circulating adipokines, such as leptin, resistin, visfatin, apelin, lipocalin 2, osteopontin, and oncostatin M, is elevated in BC, while some adipokines such as adiponectin and irisin (adipo-myokine) are generally decreased in BC and considered protective against breast carcinogenesis. Further evidence from basic and translational research is necessary to delineate the ontological role of adipokines and their interplay in BC pathogenesis. More large-scale clinical and longitudinal studies are awaited to assess their clinical utility in BC prognosis and follow-up. Finally, novel more effective and safer adipokine-centered therapeutic strategies could pave the way for targeted oncotherapy.

Molecular Links between Central Obesity and Breast Cancer

Worldwide, breast cancer (BC) is the most common malignancy in women, in regard to incidence and mortality. In recent years, the negative role of obesity during BC development and progression has been made abundantly clear in several studies. However, the distribution of body fat may be more important to analyze than the overall body weight. In our review of literature, we reported some key findings regarding the role of obesity in BC development, but focused more on central adiposity. Firstly, the adipose microenvironment in obese people bears many similarities with the tumor microenvironment, in respect to associated cellular composition, chronic low-grade inflammation, and high ratio of reactive oxygen species to antioxidants. Secondly, the adipose tissue functions as an endocrine organ, which in obese people produces a high level of tumor-promoting hormones, such as leptin and estrogen, and a low level of the tumor suppressor hormone, adiponectin. As follows, in BC this leads to the activation of oncogenic signaling pathways: NFκB, JAK, STAT3, AKT. Moreover, overall obesity, but especially central obesity, promotes a systemic and local low grade chronic inflammation that further stimulates the increase of tumor-promoting oxidative stress. Lastly, there is a constant exchange of information between BC cells and adipocytes, mediated especially by extracellular vesicles, and which changes the transcription profile of both cell types to an oncogenic one with the help of regulatory non-coding RNAs.

Adipocytes and microRNAs Crosstalk: A Key Tile in the Mosaic of Breast Cancer Microenvironment

Breast cancer (BC) is a disease characterized by a high grade of heterogeneity. Consequently, despite the great achievements obtained in the last decades, most of the current therapeutic regimens still fail. The identification of new molecular mechanisms that will increase the knowledge of all steps of tumor initiation and growth is mandatory in finding new clinical strategies. The BC microenvironment, consisting of endothelial cells, fibroblasts, immune cells and adipocytes, plays an essential role in regulating BC development, and recently it has gained great attention in the scientific community. In particular, adipose tissue is emerging as an important target to investigate among mammary gland components. The mechanisms underlying BC progression driven by adipocytes are predominantly unexplored, especially that involving the switch from normal adipocytes to the so-called cancer-associated adipocytes (CAAs). MicroRNAs (miRNAs), a class of gene expression modulators, have emerged as the regulators of key oncogenes and tumor suppressor genes that affect multiple pathways of the tumor microenvironment and adipose tissue. This review concerns a presentation of the role of adipocytes in breast tissue, and describes the most recent discoveries about the interplay between adipocytes and miRNAs, which collaborate in the arrangement of a pro-inflammatory and cancerous microenvironment, laying the foundations for new concepts in the prevention and treatment of BC.

The weight of obesity in breast cancer progression and metastasis: Clinical and molecular perspectives

The escalating epidemic of overweight and obesity is currently recognized as one of the most significant health and economic concern worldwide. At the present time, over 1.9 billion adults and more than 600 million people can be, respectively, classified as overweight or obese, and numbers will continue to increase in the coming decades. This alarming scenario implies important clinical implications since excessive adiposity can progressively cause and/or exacerbate a wide spectrum of co-morbidities, including type 2 diabetes mellitus, hypertension, cardiovascular disease, and even certain types of cancer, including breast cancer. Indeed, pathological remodelling of white adipose tissue and increased levels of fat-specific cytokines (mainly leptin), as a consequence of the obesity condition, have been associated with several hallmarks of breast cancer, such as sustained proliferative signaling, cellular energetics, inflammation, angiogenesis, activating invasion and metastasis. Different preclinical and clinical data have provided evidence indicating that obesity may worsen the incidence, the severity, and the mortality of breast cancer. In the present review, we will discuss the epidemiological connection between obesity and breast cancer progression and metastasis and we will highlight the candidate players involved in this dangerous relationship. Since the major cause of death from cancer is due to widespread metastases, understanding these complex mechanisms will provide insights for establishing new therapeutic interventions to prevent/blunt the effects of obesity and thwart breast tumor progression and metastatic growth.

Prognostic Significance of Abdominal-to-Gluteofemoral Adipose Tissue Distribution in Patients with Breast Cancer

This study aimed to evaluate the association between abdominal-to-gluteofemoral adipose tissue (AT) distribution and recurrence-free survival (RFS) in breast cancer patients. Staging F-18 fluorodexoyglucose (FDG) positron emission tomography/computed tomography (PET/CT) images of 336 women with breast cancer were retrospectively analyzed. From CT images, the volume and CT-attenuation of visceral adipose tissue (VAT), abdominal subcutaneous adipose tissue (SAT), and gluteofemoral AT were measured and the ratio of abdomen-to-gluteofemoral AT volume (AG volume ratio) was calculated. The relationships between adipose tissue parameters and RFS were assessed. Through univariate analysis, abdominal SAT volume, gluteofemoral AT volume, and AG volume ratio were significantly associated with RFS. An increase in abdominal SAT volume and AG volume ratio were associated with an increased risk of recurrence, whereas increased gluteofemoral AT volume was associated with a decreased risk of recurrence. On multivariate analysis, abdominal SAT volume, gluteofemoral AT volume, and AG volume ratio were found to be significant predictors of RFS after adjusting for clinic-histological factors. Irrespective of obesity, patients with a high AG volume ratio showed a higher recurrence rate than those with a low AG volume ratio. Increased abdominal SAT volume and decreased gluteofemoral AT volume were related to poor RFS in breast cancer patients.

Genetic and epigenetic modifications of adiponectin gene: Potential association with breast cancer risk

BACKGROUND

Adipokines produced by adipose tissue are directly linked to obesity and may contribute to the pathogenesis of cancer. We hypothesized that genetic and epigenetic modifications in the adiponectin (ADIPOQ) gene and their impact on serum ADIPOQ levels may participate in increasing breast cancer (BC) risk. The present study aimed to investigate ADIPOQ +45 T/G gene polymorphism, methylation status at CpG sites -74 nucleotides (nt) and -283 nt of the ADIPOQ gene, and ADIPOQ serum levels in BC obese women.

METHODS

Serum ADIPOQ was measured by an enzyme-linked immunosorbent assay. ADIPOQ +45 T/G gene polymorphism and ADIPOQ promoter methylation status were determined using a polymerase chain reaction (PCR) and a methylation-specific PCR, respectively, in 120 obese women with BC and 120 age-matched controls.

RESULTS

ADIPOQ +45 GG genotype carriers had a significant increased risk of developing BC (odds ratio = 6.2, 95% confidence interval = 1.3-29.6, p = 0.02). ADIPOQ gene methylation at site -74 nt resulted in a 1.7-fold increased BC risk. Methylation at site -283 nt resulted in a 1.9-fold increased BC risk. Moreover serum levels of ADIPOQ were significantly decreased in BC patients and down-regulated in the presence of methylation in both examined sites. By contrast, no association between ADIPOQ gene polymorphism and serum ADIPOQ level was detected. Using both methylated sites in one panel detected cancer breast with 76.67% sensitivity and 62.18% accuracy.

CONCLUSIONS

ADIPOQ +45 T/G polymorphism and ADIPOQ promoter methylation were found to be associated with BC risk in obese Egyptian women.

Obesity and Breast Cancer: Role of Leptin

Obesity-related breast cancer is an important threat that affects especially post-menopausal women. The link between obesity and breast cancer seems to be relying on the microenvironment generated at adipose tissue level, which includes inflammatory cytokines. In addition, its association with systemic endocrine changes, including hyperinsulinemia, increased estrogens levels, and hyperleptinemia may be key factors for tumor development. These factors may promote tumor initiation, tumor primary growth, tissue invasion, and metastatic progression. Although the relationship between obesity and breast cancer is already established, the different pathophysiological mechanisms involved are not clear. Obesity-related insulin resistance is a well-known risk factor for breast cancer development in post-menopausal women. However, the role of inflammation and other adipokines, especially leptin, is less studied. Leptin, like insulin, appears to be a growth factor for breast cancer cells. There exists a link between leptin and metabolism of estrogens and between leptin and other factors in a more complex network. As a result, obesity-associated hyperleptinemia has been suggested as an important mediator in the pathophysiology of breast cancer. On the other hand, recent data on the paradoxical effect of obesity on cancer immunotherapy efficacy has brought some controversy, since the proinflammatory effect of leptin may help the effect of immune checkpoint inhibitors. Therefore, a better knowledge of the molecular mechanisms that mediate leptin action may be helpful to understand the underlying processes which link obesity to breast cancer in post-menopausal women, as well as the possible role of leptin in the response to immunotherapy in obese patients.

Leptin Modulates Exosome Biogenesis in Breast Cancer Cells: An Additional Mechanism in Cell-to-Cell Communication

Exosomes—small membrane vesicles secreted by both normal and malignant cells upon fusion of endosomal multivesicular bodies (MVBs) with the plasma membrane—play an important role in cell-to-cell communication. During the last decade, several reports have highlighted the involvement of these nanovesicles in many aspects of breast cancer development and progression, but the extracellular signals governing their generation in breast cancer cells have not been completely unraveled. Here, we investigated the role of the obesity hormone leptin, a well-known adipokine implicated in mammary tumorigenesis, on the mechanisms regulating exosome biogenesis and release in both estrogen receptor α (ERα)—positive MCF-7 and triple-negative MDA-MB-231 breast cancer cells. We found that leptin treatment enhanced the number of MVBs in the cytoplasm of breast cancer cells and increased the amount of exosomes released in cell conditioned media. At molecular level, leptin increased the protein expression of Tsg101—a key component of the endosomal sorting complex required for transport I (ESCRT-I)—by a post-transcriptional mechanism involving its direct interaction with the chaperone protein Hsp90. Targeting leptin signaling, by a selective leptin receptor antagonist the peptide LDFI (Leu-Asp-Phe-Ile), abrogated leptin effects on Tsg101 expression and on exosome secretion in breast cancer cells. In conclusion, our findings, identifying for the first time leptin/leptin receptor/Hsp90 axis as an important regulator of exosome generation in mammary carcinoma cells, suggest that targeting this signaling pathway might represent a novel therapeutic strategy to impair exosome secretion and interrupt the dangerous cell-to-cell communication in breast cancer.

The Emerging Role of Adiponectin in Female Malignancies

Obesity, characterized by excess body weight, is now accepted as a hazardous health condition and an oncogenic factor. In different epidemiological studies obesity has been described as a risk factor in several malignancies. Some biological mechanisms that orchestrate obesity-cancer interaction have been discovered, although others are still not completely understood. The unbalanced secretion of biomolecules, called "adipokines", released by adipocytes strongly influences obesity-related cancer development. Among these adipokines, adiponectin exerts a critical role. Physiologically adiponectin governs glucose levels and lipid metabolism and is fundamental in the reproductive system. Low adiponectin circulating levels have been found in obese patients, in which its protective effects were lost. In this review, we summarize the epidemiological, in vivo and in vitro data in order to highlight how adiponectin may affect obesity-associated female cancers.

Metabolic Syndrome, and Particularly the Hypertriglyceridemic-Waist Phenotype, Increases Breast Cancer Risk, and Adiponectin Is a Potential Mechanism: A Case-Control Study in Chinese Women

Objective: To investigate the association between metabolic syndrome and breast cancer and to elucidate the potential mechanism underlying this association. Patients and Methods: Based on baseline data drawn from 21 hospitals in 11 provinces of China, we performed a case-control study among 1,127 women (595 cases and 532 controls), divided into premenopausal, and postmenopausal subgroups. Student's t test, Pearson's χ² test, and logistic regression analyses were performed to ascertain the association between breast cancer and metabolic syndrome, including all of its components. In addition, we attempted to clarify the potential role of adiponectin in this association. Results: Among the components of metabolic syndrome, abnormal waist circumference was the component that markedly increased breast cancer risk in premenopausal women (OR 1.447, 95% CI 1.043-2.006). Metabolic syndrome with clusters of special risk factors showed an association with breast cancer risk. Among all these components of metabolic syndrome, the hypertriglyceridemic-waist (HW) phenotype significantly increased breast cancer risk (OR 1.56, 95% CI 1.02-2.39), regardless of menopausal status, rendering it a strong predictor of breast cancer. Total adiponectin levels and high-molecular-weight adiponectin were reversely associated with metabolic syndrome. In addition, total adiponectin levels among breast cancer patients were much lower than among controls (6.67 ± 3.05 vs. 8.01 ± 4.18, p = 0.014) only in the HW phenotype subgroup. Furthermore, the HW phenotype was associated with increased risk of estrogen receptor/progesterone receptor-positive (ER+/PR+) and -negative (ER-/PR-) breast cancer, with a 51% (OR 1.51, 95% CI 1.03-2.21) and 69% (OR 1.69, 95% CI 1.05-2.72) increase, respectively. However, there was no significant association between the HW phenotype and the ER+/PR- subtype. These results suggested that low adiponectin levels may be a mechanism that explains the association between the HW phenotype and breast cancer risk. Conclusion: Metabolic syndrome with special cluster factors is related to breast cancer risk; in particular, the HW phenotype can be regarded as a strong predictor of breast cancer. As an important factor involved in fat metabolism, adiponectin may strongly predict metabolic syndrome, especially the HW phenotype and breast cancer. Further research into this mechanism and epidemiological studies are needed. This study provides new evidence for the role of a healthy lifestyle in preventing breast cancer.