Direct role of adiponectin and adiponectin receptors in endometrial cancer: in vitro and ex vivo studies in humans

Immunological roles for resistin and related adipokines in obesity-associated tumors

Rationale Obesity is an independent risk factor for the occurrence and development of tumors. Obesity is influenced by signaling of adipokines, which are secreted factors from adipocytes and resident immune cells within adipose tissues that mediate lipid metabolism. More recently, adipokines have been implicated in chronic inflammation as well as in tumor formation and growth. Among them, resistin has received increasing attention in research related to the growth and expansion of solid tumors and hematological cancers through various signaling pathways. Objective and findings We reviewed the physiological, biochemical, and immune functions of adipose tissue, with a focus on the structure and expression of resistin and adipokines within multiple adipose cell types, their signaling pathways and putative effects on tumor cells, as well as their in vivo regulation. Current evidence indicates that adipokines such as resistin act as pro-inflammatory factors to stimulate immune cells which, in turn, promotes tumor angiogenesis, connective tissue proliferation, and matrix fibrosis. Concurrently, in states of metabolic dysfunction and lipotoxicity in obese individuals, the numbers and functions of immune cells are compromised, leading to an immunosuppressive environment that fosters tumor cell survival and weak cancer immune monitoring. Conclusion Adipokines such as resistin are important to the development of obesity-related tumors. Clarifying the roles for obesity-related factors in immune regulation and tumor progression may lead to the discovery of novel anti-tumor strategies for targeting obesity factors such as resistin to limit tumor growth and manage obesity, or both.

The mysterious association between adiponectin and endometriosis

Adiponectin is a pleiotropic cytokine predominantly derived from adipose tissue. In addition to its role in regulating energy metabolism, adiponectin may also be related to estrogen-dependent diseases, and many studies have confirmed its involvement in mediating diverse biological processes, including apoptosis, autophagy, inflammation, angiogenesis, and fibrosis, all of which are related to the pathogenesis of endometriosis. Although many researchers have reported low levels of adiponectin in patients with endometriosis and suggested that it may serve as a protective factor against the development of the disease. Therefore, the purpose of this review was to provide an up-to-date summary of the roles of adiponectin and its downstream cytokines and signaling pathways in the aforementioned biological processes. Further systematic studies on the molecular and cellular mechanisms of action of adiponectin may provide novel insights into the pathophysiology of endometriosis as well as potential therapeutic targets.

Circulating Adipocytokines and Insulin Like-Growth Factors and Their Modulation in Obesity-Associated Endometrial Cancer

The rising global incidence of uterine cancer is linked to the escalating prevalence of obesity. Obesity results in alterations in adipocytokines and IGFs, driving cancer progression via inflammation, increased cell proliferation, and apoptosis inhibition, although the precise mechanisms are still unclear. This study examined a set of six markers, namely, adiponectin, leptin, IL6, TNFα, IGF1, and IGF2 and compared them between fifty age-matched endometrial cancer patients (study group) and non-cancer patients with benign gynaecological conditions (control group). We also assessed the relationship of these markers with obesity and explored the correlation between these markers and various tumour characteristics. In the cancer population, these markers were also assessed 24 h and 6 months post-surgery. Remarkably, low adiponectin levels were associated with a 35.8% increase in endometrial cancer risk. Interestingly, compared to control subjects where IGF levels decreased after menopause, post-menopausal women in the study group showed elevated IGF1 and IGF2 levels, suggesting a potential influence of endometrial cancer on the IGF system, particularly after menopause. Lastly, it is noteworthy that a discernible inverse relationship trend was observed in the levels of adipocytokines and IGFs 6 months post-surgery. This indicates that treatment for endometrial cancer may have a differential impact on adipocytokines and IGFs, potentially holding clinical significance that merits further investigation.

Beyond Body Size: Adiponectin as a Key Player in Obesity-Driven Cancers

Obesity, a complex and multifactorial disease influenced by genetic, environmental, and psychological factors, has reached epidemic proportions globally, posing a significant health challenge. In addition to its established association with cardiovascular disease and type II diabetes, obesity has been implicated as a risk factor for various cancers. However, the precise biological mechanisms linking obesity and cancer remain largely understood. Adipose tissue, an active endocrine organ, produces numerous hormones and bioactive molecules known as adipokines, which play a crucial role in metabolism, immune responses, and systemic inflammation. Notably, adiponectin (APN), the principal adipocyte secretory protein, exhibits reduced expression levels in obesity. In this scoping review, we explore and discuss the role of APN in influencing cancer in common malignancies, including lung, breast, colorectal, prostate, gastric, and endometrial cancers. Our review aims to emphasize the critical significance of investigating this field, as it holds great potential for the development of innovative treatment strategies that specifically target obesity-related malignancies. Furthermore, the implementation of more rigorous and comprehensive prevention and treatment policies for obesity is imperative in order to effectively mitigate the risk of associated diseases, such as cancer.

Role of adipocytokines in endometrial cancer progression

Endometrial cancer is considered a significant barrier to increasing life expectancy and remains one of the most common malignant cancers among women in many countries worldwide. The increasing mortality rates are potentially proportional to the increasing obesity incidence. Adipose tissue secretes numerous adipocytokines, which may play important roles in endometrial cancer progression. In this scenario, we describe the role of adipocytokines in cell proliferation, cell invasion, cell adhesion, inflammation, angiogenesis, and anti-apoptotic action. A better understanding of the mechanisms of these adipocytokines may open up new therapeutic avenues for women with endometrial cancer. In the future, larger prospective studies focusing on adipocytokines and specific inhibitors should be directed at preventing the rapidly increasing prevalence of gynecological malignancies.

Adiponectin: A player in the pathogenesis of hormone-dependent cancers

Hormone-dependent cancers are a major cause of morbidity and mortality in both genders. Accumulating evidence suggest that adiponectin, an adipokine with multifaceted functions, is implicated in the pathogenesis of several malignancies. In the present review, we discuss the existing data regarding this relationship. Several observational studies showed that low adiponectin levels are associated with higher risk for breast, cervical, endometrial, ovarian and prostate cancer. A relationship between adiponectin and the aggressiveness of some of these tumors has also been reported. In vitro studies reported that adiponectin inhibits the proliferation and induces apoptosis of breast, cervical, endometrial, ovarian and prostate cancer cells. Given the high prevalence of these cancers and the substantial associated morbidity and mortality, the role of agents that increase adiponectin levels and/or stimulate its activity should be evaluated for the prevention and management of these common tumors.

Role of Leptin and Adiponectin in Endometrial Cancer

Endometrial cancer is the most common malignancy of the female genital tract. Obesity is a strong risk factor for endometrial cancer. Adipose tissue is an active endocrine organ that synthesizes biologically active cytokine peptides, called adipokines. Adiponectin and leptin are the main cytokines of adipose tissue, which may influence the development of metabolic diseases and carcinogenesis. In this scenario, we describe the role of leptin and adiponectin in the development of endometrial cancer. A better understanding of the signalling pathway of these cytokines in endometrial cancerogenesis will provide an opportunity for effective target therapy and may be usable in fertility-sparing treatment. In the future, clinical trials focusing on adipokines, molecular biology, and genetics of the tumour will be needed.

Adipocytokines and disease progression in endometrial cancer: a systematic review

The objective of the study was to document the effect of adipocytokines on endometrial cancer progression. A search of the databases CINAHL, Medline, PubMed, Cochrane, Web of Science, Embase and Google Scholar was performed for English language articles from January 2000 to December 2020 using the keywords: (Endometrial cancer) AND (progression OR metastasis) AND (adipocytokine OR adiponectin OR leptin OR visfatin OR IL-6 OR TNF-α OR adipokine OR cytokine). Forty-nine studies on adipocytokines have been included in this review. Adiponectin has been linked with anti-proliferative and anti-metastatic effects on endometrial cancer cells and is associated with a better prognosis. Leptin, visfatin and resistin are linked to the stimulation of endometrial cancer growth, proliferation, invasion and metastasis and are associated with worse prognosis or with a higher grade/stage of endometrial cancer. IL-6, Il-11, IL-31, IL-33, TNF-α, TGF-β1, SDF-1 and CXCR are involved in endometrial cancer cell growth and metastasis or involved in epithelial mesenchymal transformation (EMT) or associated with advanced disease. Adipocytokines have been found to directly impact endometrial cancer cell proliferation, invasion and migration. These molecules and their signalling pathways may be used to determine prognosis and course of the disease and may also be exploited as potential targets for cancer treatment and prevention of progression.

The Roles of Tricellular Tight Junction Protein Angulin-1/Lipolysis-Stimulated Lipoprotein Receptor (LSR) in Endometriosis and Endometrioid-Endometrial Carcinoma

Tight junction proteins play roles beyond permeability barriers functions and control cell proliferation and differentiation. The relation between tight junctions and the signal transduction pathways affects cell growth, invasion and migration. Abnormality of tight junction proteins closely contributes to epithelial mesenchymal transition (EMT) and malignancy of various cancers. Angulin-1/lipolysis-stimulated lipoprotein receptor (LSR) forms tricellular contacts that has a barrier function. Downregulation of angulin-1/LSR correlates with the malignancy in various cancers, including endometrioid-endometrial carcinoma (EEC). These alterations have been shown to link to not only multiple signaling pathways such as Hippo/YAP, HDAC, AMPK, but also cell metabolism in ECC cell line Sawano. Moreover, loss of angulin-1/LSR upregulates claudin-1, and loss of apoptosis stimulating p53 protein 2 (ASPP2) downregulates angulin-1/LSR. Angulin-1/LSR and ASPP2 concentrate at both midbody and centrosome in cytokinesis. In EEC tissues, angulin-1/LSR and ASPP2 are reduced and claudin-2 is overexpressed during malignancy, while in the tissues of endometriosis changes in localization of angulin-1/LSR and claudin-2 are seen. This review highlights how downregulation of angulin-1/LSR promotes development of endometriosis and EEC and discusses about the roles of angulin-1/LSR and its related proteins, including claudins and ASPP2.

Effects of Metabolic Syndrome and Its Components on the Prognosis of Endometrial Cancer

Objective

To explore the effects of metabolic syndrome (MetS) on the prognosis of endometrial cancer (EC) and to identify key components of MetS associated with EC.

Methods

A total of 506 patients surgically diagnosed with EC were analyzed in this study. These patients were diagnosed with EC in the Department of Obstetrics and Gynecology at the People's Hospital of Peking University between 2010 and 2016. The follow-up time was cut off at December 2019. MetS was characterized based on standards provided by the Chinese Diabetes Society in 2004.

Results

Among the 506 EC patients analyzed, 153 patients were diagnosed with MetS. MetS patients were more likely to be older and postmenopausal. MetS was positively related to tumor grade, stage, LNM, LVSI, and MI. The univariate analysis showed that MetS was closely related to the OS (HR = 2.14; P = 0.032) and RFS (HR = 1.80; P = 0.045) of EC patients. K-M analysis also indicated that EC patients with MetS had shorter OS and RFS than EC patients without MetS. More specifically, patients that had ≥3 components showed a worse outcome compared with patients only having 0 or 1-2 components (P <0.05). In the multivariate-adjust model, after adjusting for age, histotype, tumor grade, and stage, HDL-C was found to be associated with increased risk of death related to EC (HR = 2.2, P = 0.034). However, MetS did not significantly correlate with this. ROC analysis revealed that the area under the ROC curve of combined factors (HDL-C + grade + stage) was better than traditional stage or grade at 1-, 3-, and 5-year survival rates. From this, a nomogram based on HDL-C, grade, and stage was constructed to predict survival of EC patients. Calibration curve analysis and decision curve analysis (DCA) showed the nomogram we constructed could better predict the survival of EC patients.

Conclusion

MetS is closely related to poor prognosis in EC patients. The prevalence of individual MetS components increase with worse outcomes in EC patients. A nomogram based on HDL-C, grade, and stage has good ability to predict survival of EC patients.

Another Weapon against Cancer and Metastasis: Physical-Activity-Dependent Effects on Adiposity and Adipokines

Physically active behavior has been associated with a reduced risk of developing certain types of cancer and improved psychological conditions for patients by reducing anxiety and depression, in turn improving the quality of life of cancer patients. On the other hand, the correlations between inactivity, sedentary behavior, and overweight and obesity with the risk of development and progression of various cancers are well studied, mainly in middle-aged and elderly subjects. In this article, we have revised the evidence on the effects of physical activity on the expression and release of the adipose-tissue-derived mediators of low-grade chronic inflammation, i.e., adipokines, as well as the adipokine-mediated impacts of physical activity on tumor development, growth, and metastasis. Importantly, exercise training may be effective in mitigating the side effects related to anti-cancer treatment, thereby underlining the importance of encouraging cancer patients to engage in moderate-intensity activities. However, the strong need to customize and adapt exercises to a patient’s abilities is apparent. Besides the preventive effects of physically active behavior against the adipokine-stimulated cancer risk, it remains poorly understood how physical activity, through its actions as an adipokine, can actually influence the onset and development of metastases.

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.

Endometrial Cancer as a Metabolic Disease with Dysregulated PI3K Signaling: Shedding Light on Novel Therapeutic Strategies

Endometrial cancer (EC) is one of the most common malignancies of the female reproductive organs. The most characteristic feature of EC is the frequent association with metabolic disorders. However, the components of these disorders that are involved in carcinogenesis remain unclear. Accumulating epidemiological studies have clearly revealed that hyperinsulinemia, which accompanies these disorders, plays central roles in the development of EC via the insulin-phosphoinositide 3 kinase (PI3K) signaling pathway as a metabolic driver. Recent comprehensive genomic analyses showed that over 90% of ECs have genomic alterations in this pathway, resulting in enhanced insulin signaling and production of optimal tumor microenvironments (TMEs). Targeting PI3K signaling is therefore an attractive treatment strategy. Several clinical trials for recurrent or advanced ECs have been attempted using PI3K-serine/threonine kinase (AKT) inhibitors. However, these agents exhibited far lower efficacy than expected, possibly due to activation of alternative pathways that compensate for the PIK3-AKT pathway and allow tumor growth, or due to adaptive mechanisms including the insulin feedback pathway that limits the efficacy of agents. Overcoming these responses with careful management of insulin levels is key to successful treatment. Further interest in specific TMEs via the insulin PI3K-pathway in obese women will provide insight into not only novel therapeutic strategies but also preventive strategies against EC.

Association between metabolic syndrome and endometrial cancer risk: a systematic review and meta-analysis of observational studies

Existing evidence has revealed inconsistent results on the association between metabolic syndrome (MetS) and endometrial cancer (EC) risk. Herein, we aim to better understand this association. Systematic searches of PubMed, EMBASE, and Web of Science through 12 December 2019 were conducted. Observational studies that provided risk estimates of MetS and EC risk were eligible. The quality of the included studies was judged based on the Newcastle–Ottawa scale. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random-effects model. Six studies, comprising 17,772 EC cases and 150,371 participants were included. MetS, diagnosed according to the criteria of the National Cholesterol Education Program—Third Adult Treatment Panel, was associated with an increased risk of EC (OR: 1.62; 95% CI = 1.26–2.07) with substantial heterogeneity (I² = 78.3%). Furthermore, we found that women with MetS, diagnosed according to the criteria of the International Diabetes Federation, had a significantly higher risk of EC compared to healthy controls (OR: 1.45; 95% CI = 1.16–1.81; I² = 64.6%). Our findings were generally consistent with the main results in the majority of prespecified subgroups, as well as in sensitivity analyses. In conclusion, MetS is associated with EC risk.

Evaluation of Changes in the Expression Profile of mRNA and Proteinencoding Adiponectin in Ishikawa Cell Line under the Influence of Cisplatin - Preliminary Report

Background

A reduced concentration of adiponectin is considered as an independent factor of the risk of inducing endometrial cancer. Cisplatin is a drug used in the therapy of this type of neoplasm. However, knowledge of the effects of cisplatin on the adiponectin level is still limited.

Objective

The purpose of this study was to assess the impact of cisplatin depending on the concentration and time of exposition of the cells to the drug on the adiponectin level in the endometrial cancer cell line.

Methods

Cells of endometrial cancer cell line Ishikawa were exposed for 12,24 and 48 hour periods to cisplatin with the following concentrations: 2.5µM, 5µM, 10µM. The changes in the expression profile of adiponectin were compared to the RtqPCR reaction and ELISA test. The STATISTICA 13.0 PL program was used for statistical analysis (p<0.05).

Results

In the culture without the drug, the concentration of adiponectin was statistically lower than in the cell culture incubated with the drug. Changes on the mRNA level seem to be more specific than on the protein level, although in both cases, the same trend in the expression changes was noted.

Discussion

The longer the time of exposition of the cells to the drug, the expression of mRNA, and the adiponectin protein increased. Changes in the expression profile were characterized statistically (p<0.05).

Conclusion

Cisplatin, in a noticeable way, changes the expression profile of adiponectin. Molecular analysis indicated that in the case of endometrial cancer therapy should be implemented with a concentration of no less than 5 µM.

The Role of Metabolic Syndrome in Endometrial Cancer: A Review

Endometrial cancer is one of the most common cancers of the female reproductive system. Although surgery, radiotherapy, chemotherapy, and hormone therapy can significantly improve the survival of patients, the treatment of patients with very early lesions and a strong desire to retain reproductive function or late recurrence is still in the early stages. Metabolic syndrome (MS) is a clustering of at least three of the five following medical conditions: central obesity, high blood pressure, high blood sugar, high serum triglycerides, and low serum high-density lipoprotein (HDL). Obesity, diabetes and hypertension often coexist in patients with endometrial cancer, which increases the risk of endometrial cancer, also known as the "triple syndrome of endometrial cancer." In recent years, epidemiological and clinical studies have found that MS associated with metabolic diseases is closely related to the incidence of endometrial cancer. However, the key molecular mechanisms underlying the induction of endometrial cancer by MS have not been elucidated to date. Characterizing the tumor metabolism microenvironment will be advantageous for achieving a comprehensive view of the molecular mechanism of metabolic syndrome associated with endometrial cancer and for providing a new target for the treatment of endometrial cancer. This review focuses on recent advances in determining the role of metabolic syndrome-related factors and mechanisms in the pathogenesis of endometrial cancer. We suggest that interfering with the tumor metabolic microenvironment-related molecular signals may inhibit the occurrence of endometrial cancer.

The Adiponectin-AdipoR1 Axis Mediates Tumor Progression and Tyrosine Kinase Inhibitor Resistance in Metastatic Renal Cell Carcinoma

The survival of patients diagnosed with metastatic renal cell carcinoma (RCC) is still limited and the current targeted therapies are only partially effective. Herein, we investigated the clinical value and functions of adiponectin receptors (AdipoR1 and AdipoR2) in metastatic renal cell carcinoma (RCC) patients treated with tyrosine kinase inhibitors (TKIs). A total of 127 mRCC patients treated with first-line TKIs between 2008 and 2017 at a single institution were collected. AdipoR1 and AdipoR2 expression was assessed by immunohistochemistry. AdipoR1 was positively expressed in 87.4% (111/127) of tumors, especially, highly expressed in pulmonary and bone lesions. Patients with low-AdipoR1 expression in primary tumor tissues were more likely to suffer from progressive disease during TKIs treatment (40.0% vs. 11.1%, P = 0 .02), and with decreased progression-free survival (PFS: 19.5 vs. 37.8 mo, P = .001) and overall survival (OS: 62.3 vs 101.1 mo, P = .004) compared to those with high-AdipoR1 expression. Moreover, low-AdipoR1 expression in metastatic tissues was also associated with poor PFS (P = .006) and OS (P = .037). In contrast, AdipoR2 expression was neither associated with sunitinib response nor patient survival. In vitro, we found that adiponectin inhibited migration, invasion and sensitized RCC cells to sunitinib though interacting with AdipoR1, but not AdipoR2. Furthermore, we demonstrated that adiponentin-AdipoR1 axis inhibits tumor cells migration and invasion by blocking the GSK3β/β-Catenin pathway and enhances sunitinib sensitivity via abrogating PI3K/AKT/NF-κB signaling. Our results suggest that adiponentin-AdipoR1 axis may serve as a predictor of TKIs response and could be a potential therapeutic target in the future treatment for metastatic RCC.

Adiponectin receptor agonist AdipoRon induces apoptotic cell death and suppresses proliferation in human ovarian cancer cells

We tested the hypothesis that stimulation of adiponectin receptors with the synthetic agonist AdipoRon suppresses proliferation and induces apoptotic death in human high grade serous ovarian tumor cell lines and in ex vivo primary tumors, mediated by activation of 5' AMP-activated protein kinase (AMPK) and inhibition of mechanistic target of rapamycin (mTOR). We determined the effect of AdipoRon on high grade serous ovarian tumor cells lines (OVCAR3, OVCAR4, A2780) and ex vivo primary tumor tissue. Western blotting analysis was performed to examine changes in activation of AMPK and mTOR signaling and flow cytometry was utilized to examine changes in cell cycle progression. Immunofluorescence of cleaved caspase-3 positive cells and flow cytometry of annexin V positive cells were used to determine changes in apoptotic response. The CyQUANT proliferation assay was used to assess cell proliferation. AdipoRon treatment increased AMPK phosphorylation (OVCAR3 P = 0.01; A2780 P = 0.02) but did not significantly alter mTOR activity. AdipoRon induced G1 cell cycle arrest in OVCAR3 (+ 12.1%, P = 0.03) and A2780 (+ 12.0%, P = 0.002) cells. OVCAR3 and OVCAR4 cells treated with AdipoRon underwent apoptosis based on cleaved caspase-3 and annexin V staining. AdipoRon treatment resulted in a dose dependent decrease in cell number versus vehicle treatment in OVCAR3 (-61.2%, P < 0.001), OVCAR4 (-79%, P < 0.001), and A2780 (-56.9%, P < 0.001). Ex vivo culture of primary tumors treated with AdipoRon resulted in an increase in apoptosis measured with cleaved caspase-3 immunohistochemistry. AdipoRon induces activation of AMPK and exhibits an anti-tumor effect in ovarian cancer cell lines and primary tumor via a mTOR-independent pathway.

Adipose Tissue, Obesity and Adiponectin: Role in Endocrine Cancer Risk

Adipose tissue has been recognized as a complex organ with endocrine and metabolic roles. The excess of fat mass, as occurs during overweight and obesity states, alters the regulation of adipose tissue, contributing to the development of obesity-related disorders. In this regard, many epidemiological studies shown an association between obesity and numerous types of malignancies, comprising those linked to the endocrine system (e.g., breast, endometrial, ovarian, thyroid and prostate cancers). Multiple factors may contribute to this phenomenon, such as hyperinsulinemia, dyslipidemia, oxidative stress, inflammation, abnormal adipokines secretion and metabolism. Among adipokines, growing interest has been placed in recent years on adiponectin (APN) and on its role in carcinogenesis. APN is secreted by adipose tissue and exerts both anti-inflammatory and anti-proliferative actions. It has been demonstrated that APN is drastically decreased in obese individuals and that it can play a crucial role in tumor growth. Although literature data on the impact of APN on carcinogenesis are sometimes conflicting, the most accredited hypothesis is that it has a protective action, preventing cancer development and progression. The aim of the present review is to summarize the currently available evidence on the involvement of APN and its signaling in the etiology of cancer, focusing on endocrine malignancies.

Type-II endometrial cancer: role of adipokines

BACKGROUND

Type-II endometrial cancer is an estrogen independent and one of the most lethal types of cancer having poor prognosis. Adipokines play a crucial role in the triggering Type-II EMC. In addition, adipokines modulators, therefore, may have beneficial effects in the treatment of Type-II endometrial cancer, which was clinically evidenced.

AREAS COVERED

This review presents the role of various adipokines involved and also the suitable modulators to treat Type-II endometrial cancer.

CONCLUSION

In the present review, we try to discuss the role of individual adipokines in the pathogenesis of Type-II endometrial cancer, and also the possible beneficial effects of adipokines modulator in the treatment of Type-II endometrial 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.

Mechanisms of Adiponectin Action in Fertility: An Overview from Gametogenesis to Gestation in Humans and Animal Models in Normal and Pathological Conditions

Adiponectin is the most abundant plasma adipokine. It mainly derives from white adipose tissue and plays a key role in the control of energy metabolism thanks to its insulin-sensitising, anti-inflammatory, and antiatherogenic properties. In vitro and in vivo evidence shows that adiponectin could also be one of the hormones controlling the interaction between energy balance and fertility in several species, including humans. Indeed, its two receptors—AdipoR1 and AdipoR2—are expressed in hypothalamic–pituitary–gonadal axis and their activation regulates Kiss, GnRH and gonadotropin expression and/or secretion. In male gonads, adiponectin modulates several functions of both somatic and germ cells, such as steroidogenesis, proliferation, apoptosis, and oxidative stress. In females, it controls steroidogenesis of ovarian granulosa and theca cells, oocyte maturation, and embryo development. Adiponectin receptors were also found in placental and endometrial cells, suggesting that this adipokine might play a crucial role in embryo implantation, trophoblast invasion and foetal growth. The aim of this review is to characterise adiponectin expression and its mechanism of action in male and female reproductive tract. Further, since features of metabolic syndrome are associated with some reproductive diseases, such as polycystic ovary syndrome, gestational diabetes mellitus, preeclampsia, endometriosis, foetal growth restriction and ovarian and endometrial cancers, evidence regarding the emerging role of adiponectin in these disorders is also discussed.

Roles of Adiponectin Signaling Related Proteins in Mammary Tumor Development

Objective

This study aims to investigate the expression levels of adiponectin signaling related proteins in mammary tissue, liver and breast cancer tissue in mice. Adiponectin, an adipocytokine, is secreted from adipose tissue and has been documented to have roles in diabetes, inflammation, and cancer development. In particular, levels of serum adiponectin are inversely associated with obesity and a decrease in serum adiponectin levels have been reported to be associated with breast cancer. There are two adiponectin receptor subtypes, AdipoR1 and AdipoR2, which have been identified in mammalian tissues, including human cancer cell lines and also in human mammary tumors. However, the role of adiponectin receptors in breast cancer development remains to be established.

Methods

In this study, MMTV-TGF-α transgenic mice were fed from week 10 up to week 74 of age. Expression levels of adiponectin, AdipoR1 and AdipoR2 proteins were measured in the mammary fat pad (MFP), mammary tumor (MT) and liver tissues from 74 weeks old MMTV-TGF-α transgenic mice with and without MT using Western Blot. Adiponectin levels were measured using ELISA assay.

Results

Protein expression levels of Adiponectin and AdipoR1 were significantly lower in MTs compared to control tissues. However, AdipoR2 protein expression levels were similar in MT and MFP tissues from MT-positive and MT-negative mice. The expression levels of adiponectin, AdipoR1 and AdipoR2 proteins in liver tissues were also similar in MT-positive and MT-negative mice. Serum adiponectin levels of the MT-positive and MT-negative mice were similar.

Conclusion

These results indicate that adiponectin and its receptors are differentially regulated depending upon the specific tissue analyzed. AdipoR1 and adiponectin may play important roles in MT development.

Effect of High-fat Diet-induced Disorders on Rat with Endometrial Hyperplasia and Adiponectin System in Circulation and Uterus

Background:

Epidemiologic and genetic studies suggest a link between insulin resistance (IR) and endometrial cancer, and endometrial hyperplasia (EH) is a precancerous stage of endometrial cancer. Adiponectin is an adipokine which previously shown to be a risk factor for endometrial cancer. The aim of the study was to develop a rat model of IR and EH and evaluate adiponectin system in circulation and uterus.

Methods:

This study was a 46-week animal trial from February 2014 to January 2015. Female Sprague-Dawley rats were fed with high-fat diet (HFD) for 40 weeks to induce IR. Followed by ovariectomization, rats were orally administrated to 17β-estradiol (E₂) for 4 weeks to induce EH and then sacrificed. A total of 36 rats were divided into four groups: E₂, HFD, HFD + E₂, and control groups. Data were analyzed with Student's t-test, one-way analysis of variance (ANOVA), and Mann-Whitney U-tests. Chi-square was used to evaluate the score of immunohistochemistry.

Results:

The thickness of endometrial, glandular epithelium, and myometrium in the HFD-E₂ group were higher than the E₂ group (F = 59.02, F = 23.51 and F = 12.53, respectively, all P < 0.001). Plasma adiponectin levels in the E₂ group were lower than those in the control group, and the levels in the HFD-E₂ group were lower than those in the HFD group (F = 13.15, P < 0.05). However, after normalized to visceral adipose tissue, compared to the control group, plasma adiponectin levels were decreased in rat with HFD in the absence or presence of E₂, respectively (F = 6.72, P < 0.05). Adiponectin gene (F = 10.48, P < 0.05) and protein (P < 0.05) levels in uterus in the HFD-E₂ group were higher than those in the HFD group.

Conclusions:

This study manifests that IR can effectively modulate EH, which suggests the involvement of energetic metabolism in uterine alternation. The combination effects of IR and EH modulate circulating adiponectin levels. However, adiponectin gene and protein levels in uterus are mainly response to estradiol.

The roles of tricellular tight junction protein lipolysis-stimulated lipoprotein receptor in malignancy of human endometrial cancer cells

Lipolysis-stimulated lipoprotein receptor (LSR) has been identified as a novel molecular constituent of tricellular contacts that have a barrier function for the cellular sheet. LSR recruits tricellulin (TRIC), which is the first molecular component of tricellular tight junctions. Knockdown of LSR increases cell motility and invasion of certain cancer cells. However, the behavior and the roles of LSR in endometrial cancer remain unknown. In the present study, we investigated the behavior and roles of LSR in normal and endometrial cancer cells in vivo and in vitro. In endometriosis and endometrial cancer, LSR was observed not only in the subapical region but also throughout the lateral region as well as in normal endometrial epithelial cells in the secretory phase, and LSR in the cancer was reduced in correlation with the malignancy. Knockdown of LSR by the siRNA in cells of the endometrial cancer cell line Sawano, induced cell migration, invasion and proliferation, while TRIC relocalized from the tricellular region to the bicellular region at the membrane. In Sawano cells and normal HEEs, a decrease of LSR induced by leptin and an increase of LSR induced by adiponectin and the drugs for type 2 diabetes metformin and berberine were observed via distinct signaling pathways including JAK2/STAT. In Sawano cells, metformin and berberine prevented cell migration and invasion induced by downregulation of LSR by the siRNA and leptin treatment. The dissection of the mechanism in the downregulation of endometrial LSR during obesity is important in developing new diagnostic and therapy for endometrial cancer.

The prognostic value of serum and bronchoalveolar lavage levels of adiponectin in advanced non-small-cell lung cancer

Aim

We aimed to explore the prognostic implications of adiponectin (APN) levels in the serum and bronchoalveolar lavage (BAL) of patients with advanced NSCLC.

Materials & methods

29 newly diagnosed patients with stage IV NSCLC were prospectively enrolled. Baseline serum and BAL levels of APN were assayed by ELISA and correlated with various clinicopathological parameters, including overall survival.

Results

No statistically significant correlations were observed between the serum or BAL levels of APN and the clinicopathological parameters evaluated. The only prognostic factor identified, both by univariate and multivariate survival analyses, was performance status.

Conclusion

The results of our cohort failed to reveal any prognostic significance of serum and BAL levels of APN in stage IV NSCLC.

Energy sensing pathways: Bridging type 2 diabetes and colorectal cancer?

The recently rapid increase of obesity and type 2 diabetes mellitus has caused great burden to our society. A positive association between type 2 diabetes and risk of colorectal cancer has been reported by increasing epidemiological studies. The molecular mechanism of this connection remains elusive. However, type 2 diabetes may result in abnormal carbohydrate and lipid metabolism, high levels of circulating insulin, insulin growth factor-1, and adipocytokines, as well as chronic inflammation. All these factors could lead to the alteration of energy sensing pathways such as the AMP activated kinase (PRKA), mechanistic (mammalian) target of rapamycin (mTOR), SIRT1, and autophagy signaling pathways. The resulted impaired SIRT1 and autophagy signaling pathway could increase the risk of gene mutation and cancer genesis by decreasing genetic stability and DNA mismatch repair. The dysregulated mTOR and PRKA pathway could remodel cell metabolism during the growth and metastasis of cancer in order for the cancer cell to survive the unfavorable microenvironment such as hypoxia and low blood supply. Moreover, these pathways may be coupling metabolic and epigenetic alterations that are central to oncogenic transformation. Further researches including molecular pathologic epidemiologic studies are warranted to better address the precise links between these two important diseases.

Supervised Clustering of Adipokines and Hormonal Receptors Predict Prognosis in a Population of Obese Women with Type 1 Endometrial Cancer

Obesity is a major risk factor for endometrial cancer (EC). Yet, its impact on prognosis is controversial. Obesity is associated with metabolic and hormonal dysregulation as well as adipokines increase. The aim of this study was to characterize the expression of biological factors related to obesity within the tumor and evaluate their impact on prognosis. One hundred and thirty-six patients, including 55 obese patients, with endometrioid type I EC operated by total hysterectomy were included in this retrospective study conducted in a Tertiary teaching hospital between 2000 and 2013. Immunohistochemistry (IHC) study was performed on type I EC tumor samples using five adipokines (SPARC, RBP4 (Retinol Binding Protein 4), adiponectin, TNF α, IL-6) and hormonal receptors (estrogen receptor and progesterone receptor). Supervised clustering of immunohistochemical markers was performed to identify clusters that could be associated with prognostic groups. The prognosis of the obese population was not different from the prognosis of the general population. Adipokine expression within tumors was not different in these two populations. In obese population, we found three clusters where co-expression was associated with a recurrence group in comparison with a non-recurrence group and four clusters where co-expression was associated with the high risk FIGO (International Federation of Gynecology and Obstetrics) stage I group in comparison of low risk FIGO stage I group. While obesity does not appear as a prognostic factor in endometrioid type I EC, the co-expression of biological factors in IHC on hysterectomy specimens allowed to distinguish two prognostic groups in obese population.

The role of adiponectin in obesity-associated female-specific carcinogenesis

Adipose tissue is a highly vascularized endocrine organ, and its secretion profiles may vary with obesity. Adiponectin is secreted by adipocytes that make up adipose tissue. Worldwide, obesity has been designated a serious health problem among women and is associated with a variety of metabolic disorders and an increased risk of developing cancer of the cervix, ovaries, uterus (uterine/endometrial), and breast. In this review, the potential link between obesity and female-specific malignancies is comprehensively presented by discussing significant features of the intriguing and complex molecule, adiponectin, with a focus on recent findings highlighting its molecular mechanism of action in female-specific carcinogenesis.

Metformin prevents aggressive ovarian cancer growth driven by high-energy diet: similarity with calorie restriction

Caloric restriction (CR) was recently demonstrated by us to restrict ovarian cancer growth in vivo. CR resulted in activation of energy regulating enzymes adenosine monophosphate activated kinase (AMPK) and sirtuin 1 (SIRT1) followed by downstream inhibition of Akt-mTOR. In the present study, we investigated the effects of metformin on ovarian cancer growth in mice fed a high energy diet (HED) and regular diet (RD) and compared them to those seen with CR in an immunocompetent isogeneic mouse model of ovarian cancer. Mice either on RD or HED diet bearing ovarian tumors were treated with 200 mg/kg metformin in drinking water. Metformin treatment in RD and HED mice resulted in a significant reduction in tumor burden in the peritoneum, liver, kidney, spleen and bowel accompanied by decreased levels of growth factors (IGF-1, insulin and leptin), inflammatory cytokines (MCP-1, IL-6) and VEGF in plasma and ascitic fluid, akin to the CR diet mice. Metformin resulted in activation of AMPK and SIRT1 and inhibition of pAkt and pmTOR, similar to CR. Thus metformin can closely mimic CR's tumor suppressing effects by inducing similar metabolic changes, providing further evidence of its potential not only as a therapeutic drug but also as a preventive agent.

INVITED REVIEW: Evolution of meat animal growth research during the past 50 years: Adipose and muscle stem cells

If one were to compare today's animal growth research to research from a mere 50 yr ago, one would see programs with few similarities. The evolution of this research from whole-animal through cell-based and finally molecular and genomic studies has been enhanced by the identification, isolation, and in vitro evaluation of adipose- and muscle-derived stem cells. This paper will highlight the struggles and the milestones that make this evolving area of research what it is today. The contribution of adipose and muscle stem cell research to development and growth, tissue regeneration, and final carcass composition are reviewed.

in vitro Anti-Proliferative Effect of Adiponectin on Human Endometriotic Stromal Cells through AdipoR1 and AdipoR2 Gene Receptor Expression

BACKGROUND

Endometriosis is a complex disorder in reproductive age women which consist of stromal and epithelial cells implantation outside the uterine cavity. Adiponectin is a member of cytokine family with various metabolic roles and proliferation inhibition of many cancer cells. The aim of the present research was to determine adiponectin effect on human endometriotic stromal cells (ESCs) proliferation and their expression of adiponectin receptors.

METHODS

In this experimental study, endometrial biopsies (n=7) were taken. ESCs isolation was done by enzymatic digestion and cell filtrations. ESCs of each biopsy were divided into four groups: 0 (control), 10, 100, and 200 ng/ml adiponectin concentrations in three different times (24, 48 or 72 h). The effect of adiponectin on ESC viability and expression of mRNA Adipo receptor1 (R1) and Adipo receptor2 (R2) was determined by Trypan blue staining and semi-quantitative RT-PCR, respectively. Data were analyzed by one-way ANOVA and unpaired student's t-test, and P<0.05 was considered statistically significant.

RESULTS

Adiponectin inhibited human endometriotic stromal cell proliferation in time- and dose-dependent manners significantly (P=0.001). Expression of AdipoR1 and AdipoR2 gene receptors was increased in human ESCs significantly (P<0.05).

CONCLUSIONS

Adiponectin can suppress endometriosis by inhibiting ESC proliferation and increased AdipoR1 and AdipoR2 expression.

Association between adiponectin levels and endometrial carcinoma risk: evidence from a dose-response meta-analysis

OBJECTIVES

Epidemiological studies evaluating the association between adiponectin levels and endometrial carcinoma risk have produced inconsistent results. Thus, a meta-analysis was conducted to assess the association between them.

METHODS

Pertinent studies were identified by a search of PubMed and Web of Knowledge through January of 2015. A random-effects model was used to combine the data for analysis. Dose-response relationship was assessed by restricted cubic spline and variance-weighted least squares regression analysis.

RESULTS

Twelve articles (5 prospective studies and 7 case-control studies) involving 1916 endometrial carcinoma cases were included in this meta-analysis. Pooled results suggested that highest adiponectin levels versus lowest levels were significantly associated with the risk of endometrial carcinoma (summary relative risk (RR)=0.525, 95% CI 0.388 to 0.712, I(2)=64.2%). The association was also found in postmenopausal women (summary RR=0.646, 95% CI 0.433 to 0.964), but not in premenopausal women. A linear dose-response relationship was found, with the risk of endometrial carcinoma decreasing by 3% for every 1 μg/mL increase in adiponectin levels (summary RR=0.97, 95% CI 0.96 to 0.98). No publication bias was found.

CONCLUSIONS

Our analysis suggested that the higher adiponectin levels might have a protective effect against endometrial carcinoma, especially in postmenopausal women.

Obesity, adipokines and cancer: an update

Obesity causes dysfunction of adipose tissue, with resultant chronic inflammation and adverse interplay of various adipokines, sex steroids and endocrine hormones. All these drive tumourigenesis and explain the epidemiological link between obesity and cancer. Over the past decade, the associations among obesity, adipokines and cancer have been increasingly recognized. Adipokines and their respective signalling pathways have drawn much research attention in the field of oncology and cancer therapeutics. This review will discuss the recent advances in the understanding of the association of several adipokines with common obesity-related cancers and the clinical therapeutic implications.

The diverse roles of adiponectin in non-small-cell lung cancer: current data and future perspectives

In recent years, there is growing research interest for the biological role of adipose tissue-derived bioactive factors, mainly including adipokines, in various forms of cancer. Adiponectin (APN) is the most abundant circulating adipokine, and a key mediator of several cancer-related processes, such as cell proliferation, apoptosis, regulation of tumor cell invasion and angiogenesis. In this review we summarize and critically discuss the published literature on the diverse roles of APN in non-small-cell lung cancer, including its implication in lung cancer development, its use as a diagnostic and prognostic biomarker, and its correlation with cancer-related cachexia. The main challenges and future perspectives, mainly with regard to the potential development of APN-targeted therapeutic agents in cancer therapeutics, are also briefly presented and discussed.

Circulating adiponectin and risk of endometrial cancer

Background

Adiponectin is an insulin-sensitizing hormone produced by adipocytes. It has been suggested to be involved in endometrial tumorigenesis. Published data have shown inconsistent results for the association between circulating adiponectin levels and endometrial cancer. In this study, we conducted a meta-analysis to evaluate the predictive value of circulating adiponectin levels on the development of endometrial cancer.

Methods

PubMed, Embase, ISI web of knowledge, and Cochrane databases were searched for all eligible studies, and the summary relative risk (SRR) was calculated. Additionally, we performed dose-response analysis with eight eligible studies.

Results

A total of 1,955 cases and 3,458 controls from 12 studies were included. The SRR for the ‘highest’ vs ‘lowest’ adiponectin levels indicated high adiponectin level reduced the risk of endometrial cancer [SRR = 0.40, 95% confidence interval (CI), 0.33–0.66]. Results from the subgroup analyses were consistent with the overall analysis. The SRR for each 1 µg/ml increase of adiponectin indicated a 3% reduction in endometrial cancer risk (95% CI: 2%–4%), and a 14% reduction for each increase of 5 µg/ml (95% CI: 9%–19%). No evidence of publication bias was found.

Conclusions

This meta-analysis demonstrates that low level of circulating adiponectin is a risk factor for endometrial cancer.

Adiponectin promotes pancreatic cancer progression by inhibiting apoptosis via the activation of AMPK/Sirt1/PGC-1α signaling

Adiponectin is an adipocyte-secreted adipokine with pleiotropic actions. Clinical evidence has shown that serum adiponectin levels are increased and that adiponectin can protect pancreatic beta cells against apoptosis, which suggests that adiponectin may play an anti-apoptotic role in pancreatic cancer (PC). Here, we investigated the effects of adiponectin on PC development and elucidated the underlying molecular mechanisms. Adiponectin deficiency markedly attenuated pancreatic tumorigenesis in vivo. We found that adiponectin significantly inhibited the apoptosis of both human and mouse pancreatic cancer cells via adipoR1, but not adipoR2. Furthermore, adiponectin can increase AMP-activated protein kinase (AMPK) phosphorylation and NAD-dependent deacetylase sirtuin-1 (Sirt1) of PC cells. Knockdown of AMPK or Sirt1 can increase the apoptosis in PC cells. AMPK up-regulated Sirt1, and Sirt1 can inversely phosphorylate AMPK. Further studies have shown that Sirt1 can deacetylate peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), which can increase the expression levels of mitochondrial genes. Thus, adiponectin exerts potent anti-apoptotic effects on PC cells via the activation of AMPK/Sirt1/PGC1α signaling. Finally, adiponectin can elevate β-catenin levels. Taken together, these novel findings reveal an unconventional role of adiponectin in promoting pancreatic cancers, and suggest that the effects of adiponectin on tumorigenesis are highly tissue-dependent.

Adiponectin mediates antiproliferative and apoptotic responses in endometrial carcinoma by the AdipoRs/AMPK pathway

OBJECTIVE

Determine the serum adiponectin levels in endometrial carcinoma (EC) cases and controls and explore the correlation between them. We assessed the functions of AdipoR1 and AdipoR2 in endometrial cancer cells to determine whether the AMPK/ERK and Akt pathways mediate the effects of adiponectin-induced apoptosis and anti-proliferation.

MATERIAL AND METHODS

The serum adiponectin levels were measured via enzyme-linked immunosorbent assay (ELISA). The proliferation and apoptosis rates were determined with MTT and annexin V/PI assays. To evaluate the activation of AMPK, ERK, and Akt and the expression of Bcl-2 and Cyclin D1, western blot analysis was performed in Ishikawa 3-H-12 cells. We down-regulated AdipoRs by si-RNA to assess their functions.

RESULTS

The serum adiponectin levels were significantly decreased in patients with EC compared to controls. The adiponectin-induced apoptosis and anti-proliferation effects in EC cells were blocked by Compound C. Ishikawa 3-H-12 cells exhibited time- and dose-dependent increases in the p-AMPK levels after treatment with adiponectin. Adiponectin treatment reduced the levels of ERK and Akt phosphorylations and cyclin D1 and Bcl-2 mRNA and protein expression. Compound C blocked the effects on ERK, Akt, cyclin D1, and Bcl-2. AdipoR1 and AdipoR2 were involved in adiponectin-induced growth inhibition and ERK activation inhibition. We speculated that AdipoR1 has a greater role than adipoR2 in apoptosis and Akt activation inhibition after adiponectin treatment.

CONCLUSION

Adiponectin was an apoptotic and anti-proliferation agent for EC cells, and these effects were dependent on the AMPK/ERK and Akt pathways. AdipoR1 and AdipoR2 may play different roles in this process.

From leptin to other adipokines in health and disease: facts and expectations at the beginning of the 21st century

This year marks the 20th anniversary of the discovery of leptin, which has tremendously stimulated translational obesity research. The discovery of leptin has led to realizations that have established adipose tissue as an endocrine organ, secreting bioactive molecules including hormones now termed adipokines. Through adipokines, the adipose tissue influences the regulation of several important physiological functions including but not limited to appetite, satiety, energy expenditure, activity, insulin sensitivity and secretion, glucose and lipid metabolism, fat distribution, endothelial function, hemostasis, blood pressure, neuroendocrine regulation, and function of the immune system. Adipokines have a great potential for clinical use as potential therapeutics for obesity, obesity related metabolic, cardiovascular and other diseases. After 20 years of intense research efforts, recombinant leptin and the leptin analog metreleptin are already available for the treatment of congenital leptin deficiency and lipodystrophy. Other adipokines are also emerging as promising candidates for urgently needed novel pharmacological treatment strategies not only in obesity but also other disease states associated with and influenced by adipose tissue size and activity. In addition, prediction of reduced type 2 diabetes risk by high circulating adiponectin concentrations suggests that adipokines have the potential to be used as biomarkers for individual treatment success and disease progression, to monitor clinical responses and to identify non-responders to anti-obesity interventions. With the growing number of adipokines there is an increasing need to define their function, molecular targets and translational potential for the treatment of obesity and other diseases. In this review we present research data on adipose tissue secreted hormones, the discovery of which followed the discovery of leptin 20 years ago pointing to future research directions to unravel mechanisms of action for adipokines.

[Influence of Body Mass Index on management and prognosis of women with endometrial cancer]

OBJECTIVE

The aim of this study was to evaluate the outcome of surgery, postoperative morbidity and prognosis of patients with endometrial cancer in function of the body mass index (BMI).

PATIENTS AND METHODS

The study cohort consisted of consecutive women undergoing surgery for endometrial cancer in our institution between January 2000, and September 2012. Individual records of all patients were reviewed and analyzed. Patient BMI was categorized as underweight, normal, overweight and obese.

RESULTS

A total of 192 patients were evaluated. Patients were followed for one to 153months with a mean of 52.56months. The mean BMI and the range of each of the BMI categories were 16.97kg/m(2) (14-18), 22.97kg/m(2) (20-24.9), 27.61kg/m(2) (25.7-29.4), 37.34kg/m(2) (30-71). Women with higher BMI were more frequently affected by hypertension (8.3%, 31.43%, 58.13% and 59.7% respectively, P<0.0001) and diabetes (16.67%, 4.3%, 13.9% and 29.85% respectively, P=0.02). Women with normal BMI had more frequently postmenopausal replacement therapy than the other categories (P=0.0004). Surgical operative time, mean length of hospitalization in days were not significantly different among the 4 groups. In the obese group there were significantly higher peroperative blood loss (P=0.01), more wound abces (P=0.05), more eventration (P=0.02) and more reinterventions for complications (P=0.03). Patients had the same protocols of treatment (surgery and adjuvant treatment) and histological characteristics were the same between groups but obese patients had much less positive lymph nodes (P=0.03). There were no statistically significant difference in overall 5-years survival between groups (P=0.54) DISCUSSION AND CONCLUSIONS: Our study demonstrate a survival equivalency for obese and non-obese women even though obese women showed less positive lymph nodes.

Skewing of immune cell cytokine production by mediators from adipocytes and endothelial cells

Since adipose tissue is composed of adipocytes as well as other cell types including endothelial cells, this study sought to determine how mediators from adipocytes and from endothelial cells impact on immune cell production of cytokines. A minimalistic design was used in which media conditioned by adipocytes or by endothelial cells were added individually or as a mixture to normal spleen cells. Media from adipocytes or endothelial cells each stimulated spleen cell production of Th1 cytokines, Th2 cytokines, most of the measured inflammatory cytokines, and some chemokines. However, a mixture of media conditioned by adipocytes and by endothelial cells inhibited production of Th1 cytokines and skewed reactivity toward a Th2 and inflammatory phenotype. Adiponectin, but not leptin, was shown to contribute to the skewing of immune responsiveness to endothelial cell-derived mediators.

Regulation of cell proliferation and malignant potential by irisin in endometrial, colon, thyroid and esophageal cancer cell lines

OBJECTIVE

Irisin is a novel hormone that has been proposed to mediate the beneficial effects of exercise on metabolism, including body weight regulation and insulin resistance. No previous studies have evaluated whether irisin may regulate cell proliferation and malignant potential of obesity-related cancer cell lines.

MATERIALS/METHODS

Cell proliferation and malignant potential i.e. cell adhesion and colony formation were studied in vitro using human and mouse obesity-related cancer cell lines i.e. endometrial (KLE and RL95-2), colon (HT29 and MCA38), thyroid (SW579 and BHP7) and esophageal (OE13 and OE33).

RESULTS

We observed that, in contrast to metformin, cell proliferation is not regulated by irisin in a dose-dependent manner in human and mouse obesity-related cancer cell lines. Specifically, physiological (5 to 10 nmol/L) and high physiological/pharmacological (50 to 100 nmol/L) concentrations of irisin had no effect on cell proliferation when compared to control in human and mouse endometrial, colon, thyroid and esophageal cancer cell lines. Also, we observed that, in contrast to metformin, neither physiological nor high physiological/pharmacological concentrations of irisin regulate cell adhesion and/or colony formation in human and mouse endometrial, colon, thyroid and esophageal cancer cell lines.

CONCLUSIONS

Our data suggest that irisin, in physiological and high physiological/pharmacological concentrations, has no in vitro effect on cell proliferation and malignant potential of obesity-related cancer cell lines. Future work is needed to determine the regulation of irisin levels and any physiological effects it may have on obesity-related cancers in vivo in animals and humans.

Clinicopathological roles of adiponectin and leptin receptors in endometrial carcinoma

To clarify the roles of adiponectin receptor (AdipoR) and leptin receptor (ObR) in endometrial carcinoma, the expression of AdipoR-1 and -2 and ObR in endometrial cancer was examined immunohistochemically, and correlations with clinicopathological implications were also analysed. Paraffin-embedded tissues were obtained from 77 patients with endometrial carcinoma and were stained immunohistochemically using antibodies against AdipoR-1, AdipoR-2 and ObR. AdipoR-1, AdipoR-2 and ObR were localised predominantly in the cell membrane and cytoplasm of tumour cells and normal endometrial cells. In 77 cases of endometrial cancer, positive expression was observed in 46 cases (59.7%) for AdipoR-1, 47 cases (61.0%) for AdipoR-2 and 33 cases (42.9%) for ObR. Expression of AdipoR-1 was observed most in stage I cases, G1 tumours, tumours with shallow myometrial invasion, tumours negative for lymphovascular space involvement, cases negative for adnexal invasion and cases with no lymph node metastasis. However, the expression of AdipoR-2 and ObR showed no correlation with any clinicopathological factors. Kaplan-Meier analyses revealed that progression-free and overall survival times were longer in cases with positive AdipoR-1 expression compared with negative AdipoR-1 expression. Poor expression of AdipoR-1, thus, appears to be associated with tumour grade, myometrial invasion, adnexal invasion, lymph-vascular space involvement and lymph node metastasis, as well as poor prognosis, in endometrial cancer.

Mechanisms linking excess adiposity and carcinogenesis promotion

Obesity constitutes one of the most important metabolic diseases being associated to insulin resistance development and increased cardiovascular risk. Association between obesity and cancer has also been well established for several tumor types, such as breast cancer in post-menopausal women, colorectal, and prostate cancer. Cancer is the first death cause in developed countries and the second one in developing countries, with high incidence rates around the world. Furthermore, it has been estimated that 15-20% of all cancer deaths may be attributable to obesity. Tumor growth is regulated by interactions between tumor cells and their tissue microenvironment. In this sense, obesity may lead to cancer development through dysfunctional adipose tissue and altered signaling pathways. In this review, three main pathways relating obesity and cancer development are examined: (i) inflammatory changes leading to macrophage polarization and altered adipokine profile; (ii) insulin resistance development; and (iii) adipose tissue hypoxia. Since obesity and cancer present a high prevalence, the association between these conditions is of great public health significance and studies showing mechanisms by which obesity lead to cancer development and progression are needed to improve prevention and management of these diseases.

Adiponectin and metformin additively attenuate IL1β-induced malignant potential of colon cancer

Both adiponectin (AD) and metformin (Met) have been proposed to downregulate cell proliferation of colon cancer cells, but whether their effect might be additive has not been studied to date. Genetic studies in humans have suggested an important role for interleukin 1β (IL1β) in cancer pathogenesis. Direct evidence that IL1β contributes to the development of colon cancer has not yet been fully confirmed and no previous studies have evaluated how IL1β may interact with AD and/or Met to regulate malignant potential and intracellular signaling pathways in human and mouse colon cancer cells. We conducted in vitro studies using human (LoVo) and mouse (MCA38) colon cancer cell lines to evaluate whether AD and Met alone or in combination may antagonize IL1β-regulated malignant potential in human and mouse colon cancer cell lines. IL1β increased malignant potential and regulated the expression of tumor suppressor (p53) and cell cycle regulatory genes (p21, p27, and cyclin E2) in human and mouse colon cancer cell lines. These effects were reversed by co-administration of AD and/or Met and were additively altered by AD and Met in combination in a STAT3- and AMPK/LKB1-dependent manner. We also observed using fluorescence activated cell sorter analysis that IL1β-regulated cell cycle progression is altered by AD and Met alone or in combination. Our novel mechanistic studies provide evidence for an important role for IL1β in colon cancer and suggest that AD and/or Met might be useful agents in the management or chemoprevention of IL1β-induced colon carcinogenesis.

Underactivation of the adiponectin-adiponectin receptor 1 axis in clear cell renal cell carcinoma: implications for progression

Energy-sensing pathways, normally coordinated by 5' AMP-activated protein kinase (AMPK), are dysregulated in renal cell carcinoma (RCC). Obesity can accentuate the pre-existing pro-tumorigenic metabolic machinery in RCC cells through its associated obesogenic hormonal milieu, characterized by lower circulating levels of adiponectin. In RCC patients, low adiponectin levels associate clinically with more aggressive disease. We investigated the adiponectin signaling pathway in RCC, focusing on adiponectin receptor 1 (AdipoR1) and associated activation of AMPK. AdipoR1 protein in RCC and normal surrounding renal tissues was determined by Western blot analysis and immunohistochemistry. Anti-tumorigenic effects of adiponectin in RCC cells in vitro were investigated via VEGF and MMP ELISA and invasion assays. Using in vivo models of RCC, the effect of AdipoR1-knockdown (shRNA) on tumor latency, growth and dissemination were determined. AdipoR1 protein was significantly reduced in clear cell RCC specimens. Adiponectin treatment inhibited VEGF, MMP-2 and MMP-9 secretion and activity and invasive and migratory capacities of RCC cells. AMPKα1-knockdown (shRNA) attenuated adiponectin's effects. In cells stably expressing AdipoR1-specific shRNA, AMPK activation by adiponectin was significantly reduced compared to cells expressing control shRNA. In vivo, AdipoR1 knockdown increased the growth, dissemination and angiogenesis of RCC. These findings suggest that deficiencies in the entire adiponectin hormonal axis (the hormone and its receptor) result in underactivation of AMPK leading to increased angiogenic and invasive capacities of RCC. The established link between obesity and RCC can therefore be further explained by the adiponectin deficiency in obese individuals together with reduced AdipoR1 protein in RCC.

Role of adiponectin and its receptors in cancer

Adiponectin (APN), a novel hormone/cytokine derived from adipocyte tissue, is involved in various physiological functions. Genetics, nutrition, and adiposity are factors contributing to circulating plasma concentrations of APN. Clinical correlation studies have shown that lower levels of serum APN are associated with increased malignancy of various cancers, such as breast and colon cancers, suggesting that APN has a role in tumorigenesis. APN affects insulin resistance, thus further influencing cancer development. Tumor cells may express receptors for APN. Cellular signaling is the mechanism by which APN exerts its host-protective responses. These factors suggest that serum APN levels and downstream signaling targets of APN may serve as potential diagnostic markers for malignancies. Further research is necessary to clarify the exact role of APN in cancer diagnosis and therapy.