Leptin promotes the proliferative response and invasiveness in human endometrial cancer cells by activating multiple signal-transduction pathways

Tumor microenvironment regulation by reactive oxygen species-mediated inflammasome activation

Tumor microenvironment (TME) is composed of diverse cell types whose interactions, both direct and indirect, significantly influence tumorigenesis and therapeutic outcomes. Within TME, reactive oxygen species (ROS) are produced by various cells and exhibit a dual role: moderate ROS levels promote tumor initiation and progression, whereas excessive levels induce cancer cell death, influencing the efficacy of anticancer therapies. Inflammasomes, cytosolic multiprotein complexes, are pivotal in multiple stages of tumorigenesis and play a crucial role in establishing the inflammatory TME. By releasing cytokines such as IL-1β and IL-18, inflammasomes contribute to immune cell recruitment and sustain a chronic inflammatory state that supports tumor growth. ROS are critical regulators of inflammasome activation, with the impact of ROS-mediated activation differing across cell types, leading to distinct influences on tumor progression and therapeutic responses. This review explores how ROS drive inflammasome activation in various TME-associated cells and the reciprocal ROS generation induced by inflammasomes, examining their multifaceted impact on tumorigenesis and therapeutic efficacy. By elucidating the complex interplay between ROS and inflammasomes in TME, we provide insights into potential therapeutic approaches that could modulate cancer progression and enhance treatment outcomes.

Leptin levels are associated with coronary artery calcification in patients with advanced prostate cancer

BACKGROUND

Convergent data suggest that advanced prostate cancer and coronary heart disease (CHD) share biological vulnerabilities that may be linked to adiposity. Here we explore whether leptin, as a marker and mediator of adiposity, could link prostate cancer to CHD.

METHODS

Patients with metastatic castration-resistant prostate cancer (mCRPC) enrolled in a phase II trial (NCT02703623) studying androgen deprivation therapy, abiraterone, prednisone, and apalutamide were eligible if they had plasma and a chest CT scan available. Coronary artery calcium (CAC) scores and adipokine levels were measured upon enrollment.

RESULTS

Of 164 patients, 87% were white. The mean age was 65.6 ± 7.5 years, 88% were either overweight or obese, 59% had hypertension, 48% had hyperlipidemia (HLD), 20% had type 2 diabetes mellitus, and 41% were former or current smokers. Coronary calcifications were found in 115 patients (70%). Among 47 patients with non-contrast chest CT scans, the median total CAC score was 133 AU (IQR 22.6-704.6). Four patients (9%) had a score of 0 AU (low risk) and 24 (51%) scores ≥100 AU, associated with high risk for major adverse cardiovascular events. Leptin levels correlated positively with the right coronary artery (RCA) CAC score [Pearson correlation coefficient (ρ) = 0.3715 (P = .0142)]. In a multivariate logistic regression analysis, older age, HLD, and higher leptin levels were independently associated with RCA calcification and a higher number of calcified coronary arteries.

CONCLUSION

Among men with mCRPC, there was a high burden of CHD, and higher leptin levels were associated with coronary atherosclerosis independently of traditional cardiac risk factors.

Association of metabolic obesity phenotypes with risk of overall and site-specific cancers: a systematic review and meta-analysis of cohort studies

BACKGROUND

Adiposity is a known risk factor for certain cancers; however, it is not clear whether the risk of cancer differs between individuals with high adiposity but different metabolic health status. The aim of this systematic literature review and meta-analysis of cohort studies was to evaluate associations between metabolic obesity phenotypes and overall and site-specific cancer risk.

METHODS

PubMed and Embase databases were used to identify relevant cohort studies up to the 6th of June 2023. Random-effects models were used to estimate summary relative risks (SRRs) and 95% confidence intervals (CIs) for the association between metabolic obesity phenotypes and cancer risk. Certainty of evidence was assessed using the Cochrane methods and the GRADE tool. This study is registered with PROSPERO, number CRD42024549511.

RESULTS

A total of 15,556 records were screened, and 31 publications covering 15 unique cohort studies were included in this analysis. Of these studies, 22 were evaluated as being at low risk of bias and 9 at moderate risk of bias. Compared to metabolically healthy normal-weight individuals (MHNW), metabolically unhealthy overweight/obese (MUOW/OB) individuals had a higher risk of overall (SRR = 1.21, 95% CI = 1.02-1.44, n = 3 studies, high certainty) and obesity-related cancers (SRR = 1.42, 95% CI = 1.15-1.74, n = 3, very low certainty). Specifically, MUOW/OB individuals were at higher risk of cancers of the postmenopausal breast (SRR = 1.32, 95% CI = 1.17-1.48, n = 7, low certainty), colorectum (SRR = 1.24, 95% CI = 1.16-1.31, n = 6, moderate certainty), endometrium (SRR = 2.31, 95% CI = 2.08-2.57, n = 4, high certainty), thyroid (SRR = 1.42, 95% CI = 1.29-1.57, n = 4, moderate certainty), kidney (SRR = 1.71, 95% CI = 1.40-2.10, n = 3, low certainty), pancreas (SRR = 1.35, 95% CI = 1.24-1.47, n = 3, high certainty), liver (SRR = 1.81, 95% CI = 1.36-2.42, n = 2, moderate certainty), gallbladder (SRR = 1.42, 95% CI = 1.17-1.73, n = 2, high certainty), bladder (SRR = 1.36, 95% CI = 1.19-1.56, n = 2, moderate certainty), and stomach (SRR = 1.50, 95% CI = 1.12-2.01, n = 2, high certainty). In addition, we found elevated risks of most of these cancers among individuals classified as MUNW and MHOW/OB phenotypes compared to those with MHNW phenotype. Our stratified analyses according to metabolic obesity phenotypes suggested that the elevated risks of some cancers were stronger in individuals with MUOW/OB versus those with MHOW/OB or MUNW phenotypes.

CONCLUSION

These findings suggest that both higher adiposity and metabolic dysfunction were independently associated with increased risk of several cancers, with the strongest associations generally observed among those with both metabolic dysfunction and obesity.

Leptin signaling promotes blood vessel formation in the Xenopus tail during the embryo-larval transition

The signals that regulate peripheral blood vessel formation during development are still under investigation. The hormone leptin promotes blood vessel formation, adipose tissue establishment and expansion, tumor growth, and wound healing, but the underlying mechanisms for these actions are currently unknown. We investigated whether leptin promotes angiogenesis in the developing tail fin using embryonic transgenic xflk-1:GFP Xenopus laevis, which express a green fluorescent protein on vascular endothelial cells to mark blood vessels. We found that leptin protein is expressed in endothelial cells of developing blood vessels and that leptin treatment via injection increased phosphorylated STAT3 signaling, which is indicative of leptin activation of its receptor, in blood vessels of the larval tail fin. Leptin administration via media increased vessel length, branching, and reconnection with the cardinal vein, while decreased leptin signaling via immunoneutralization had an opposing effect on vessel development. We also observed disorganization of major vessels and microvessels of the tail fin and muscle when leptin signaling was decreased. Reduced leptin signaling lowered mRNA expression of cenpk, gpx1, and mmp9, markers for cell proliferation, antioxidation, and extracellular matrix remodeling/cell migration, respectively, in the developing tail, providing insight into three possible mechanisms underlying leptin's promotion of angiogenesis. Together these results illustrate that leptin levels are correlated with embryonic angiogenesis and that leptin coordinates multiple aspects of blood vessel growth and development, showing that leptin is an important morphogen during embryonic development.

Update on Adipose Tissue and Cancer

Adipose tissue is the largest endocrine organ and an accepted contributor to overall energy homeostasis. There is strong evidence linking increased adiposity to the development of 13 types of cancer. With increased adiposity comes metabolic dysfunction and insulin resistance, and increased systemic insulin and glucose support the growth of many cancers, including those of the colon and endometrium. There is also an important direct crosstalk between adipose tissue and various organs. For instance, the healthy development and function of the mammary gland, as well as the development, growth, and progression of breast cancer, are heavily impacted by the breast adipose tissue in which breast epithelial cells are embedded. Cells of the adipose tissue are responsive to external stimuli, including overfeeding, leading to remodeling and important changes in the secretion of factors known to drive the development and growth of cancers. Loss of factors like adiponectin and increased production of leptin, endotrophin, steroid hormones, and inflammatory mediators have been determined to be important mediators of the obesity-cancer link. Obesity is also associated with a structural remodeling of the adipose tissue, including increased localized fibrosis and disrupted angiogenesis that contribute to the development and progression of cancers. Furthermore, tumor cells feed off the adipose tissue, where increased lipolysis within adipocytes leads to the release of fatty acids and stromal cell aerobic glycolysis leading to the increased production of lactate. Both have been hypothesized to support the higher energetic demands of cancer cells. Here, we aim to provide an update on the state of the literature revolving around the role of the adipose tissue in cancer initiation and progression.

Low-Density Lipoprotein Contributes to Endometrial Carcinoma Cell Proliferation, Migration, and Invasion by Activating the JAK-STAT Signaling Pathway

Background

Cholesterol-rich low-density lipoprotein (LDL) particles have been demonstrated to regulate breast cancer cell proliferation and migration, but their biological function and relevant mechanisms in endometrial carcinoma (EC) remain unclear.

Methods

Serum and tissue samples were collected from EC patients (n = 50) and patients with benign endometrial hyperplasia (n = 50). Ishikawa and RL95-2 cells were stimulated with different concentrations of LDL, followed by treatment with a JAK2 inhibitor (SD-1029). LDL concentrations were determined by ELISA. The in vitro biological behavior of cells was examined using the CCK-8 assay, EdU staining, and Transwell assay. The tumorigenicity of LDL in vivo was examined using a xenograft mouse model. western blotting, immunofluorescence, and immunohistochemistry studies were performed to measure related protein expression.

Results

The LDL concentrations and levels of p-JAK2 and p-STAT3 expression were elevated in the clinical samples. Similar trends in expression were detected in EC cells after LDL stimulation. LDL treatment significantly promoted EC cell proliferation, migration, and invasion, and also upregulated p-JAK2 and p-STAT3 expression in a dose-dependent manner. Moreover, SD-1029 dramatically blocked the LDL-mediated effects on EC cells. Intravenous injection of LDLs promoted tumor growth in the xenograft nude mice, and also increased p-JAK2, p-STAT3, and Ki-67 expression, and downregulated caspase-3 expression.

Conclusions

These findings indicate that LDLs exert an oncogenic effect in EC cells by activating the JAK/STAT signaling pathway, and also suggest the JAK/STAT pathway as a possible therapeutic target for EC.

Connecting the dots in the associations between diet, obesity, cancer, and microRNAs

The prevalence of obesity has reached pandemic levels worldwide, leading to a lower quality of life and higher health costs. Obesity is a major risk factor for noncommunicable diseases, including cancer, although obesity is one of the major preventable causes of cancer. Lifestyle factors, such as dietary quality and patterns, are also closely related to the onset and development of obesity and cancer. However, the mechanisms underlying the complex association between diet, obesity, and cancer remain unclear. In the past few decades, microRNAs (miRNAs), a class of small non-coding RNAs, have been demonstrated to play critical roles in biological processes such as cell differentiation, proliferation, and metabolism, highlighting their importance in disease development and suppression and as therapeutic targets. miRNA expression levels can be modulated by diet and are involved in cancer and obesity-related diseases. Circulating miRNAs can also mediate cell-to-cell communications. These multiple aspects of miRNAs present challenges in understanding and integrating their mechanism of action. Here, we introduce a general consideration of the associations between diet, obesity, and cancer and review the current knowledge of the molecular functions of miRNA in each context. A comprehensive understanding of the interplay between diet, obesity, and cancer could be valuable for the development of effective preventive and therapeutic strategies in future.

Leptin: A Heavyweight Player in Obesity-Related Cancers

Obesity, defined as the abnormal or excessive expansion of white adipose tissue, has reached pandemic proportions and is recognized as an important health concern since it is a common root for several comorbidities, including malignancies. Indeed, the current knowledge of the white adipose tissue, which shifts its role from an energy storage tissue to an important endocrine and metabolic organ, has opened up new avenues for the discovery of obesity's effects on tumor biology. In this review, we will report the epidemiological studies concerning the strong impact of obesity in several types of cancer and describe the mechanisms underlying the heterotypic signals between cancer cell lines and adipocytes, with particular emphasis on inflammation, the insulin/IGF-1 axis, and adipokines. Among the adipokines, we will further describe the in vitro, in vivo, and clinical data concerning the role of leptin, recognized as one of the most important mediators of obesity-associated cancers. In fact, leptin physiologically regulates energy metabolism, appetite, and reproduction, and several studies have also described the role of leptin in affecting cancer development and progression. Finally, we will summarize the newest pharmacological strategies aimed at mitigating the protumorigenic effects of leptin, underlining their mechanisms of action.

The Relationship Between Leptin Receptor Expression and Endometrial Carcinoma; A Case-Control Study

Background & Objective

Endometrial carcinoma is one of the most common malignancies in women in developed countries and the fourth malignancy in Iranian women. Therefore, the identification of its causative factors is essential for the prevention, diagnosis, and treatment. This study was aimed to compare the leptin receptor (Ob-R) expression in the endometrial carcinoma cases and non-carcinoma samples.

Methods

In this case-control study, 89 samples (including 45 carcinoma and 44 non-carcinoma samples) were examined. The carcinomatous samples were selected by the census method and others were selected with random method. The data were obtained from histopathologic diagnosis, immunohistochemistry (negative, positive and intensity of immunoreactivity), age, history of diabetes, and hypertension. Ob-R expression was compared in the studied groups using Chi-square, Fisher tests and Multivariate logistic regression analysis. In all tests the level of significance was set at 0.05. The SPSS 26 was used for data analysis.

Results

The frequency of high levels of leptin receptors in the patients with endometrial carcinoma was significantly higher compared to the control group (57.8% vs. 2.3%) (P<0.05). Adjusting the effects of age, history of diabetes mellitus (DM) and hypertension (HTN) revealed that the positive-receptor group had 37.75 (95% CI; 5.18-275.04) odds of having endometrial carcinoma (P<0.001).

Conclusion

The leptin receptor may be a risk factor for the endometrial carcinoma among women tested in Kashan. Based on these results, leptin receptor might be considered as a potential biomarker for screening the endometrial carcinoma or targeting the therapeutic purposes.

Obesity and cancer: focus on leptin

Over the past decades, obesity has grown to epidemic proportions worldwide. It has been associated with an increased risk for different types of cancer. In addition, obesity has been associated with a poor prognosis, an increased risk of metastasis and mortality, and resistance to anti-cancer therapies. The pathophysiological mechanisms underlying the obesity-cancer connection have not yet been fully elucidated. However, this connection could result, at least in part, from the action of adipokines, whose levels are increased in obesity. Among these adipokines, evidence suggests leptin's critical role in linking obesity to cancer. In this review, we first summarize the current state of the literature regarding the implication of leptin in tumorigenic processes. Next, we focus on the effects of leptin on the anti-tumor immune response. Then, we discuss the influence of leptin on the efficiency of antineoplastic treatments and the development of tumor resistance. Finally, we highlight the use of leptin as a potential target for the prevention and treatment of cancer.

Obesity and multiple myeloma: emerging mechanisms and perspectives

Obesity is a global pandemic that has been associated with the development of breast, endometrial, large intestine, renal, esophageal, and pancreatic cancer. Obesity is also involved in the development of cardiovascular disease and type 2 diabetes mellitus. Recently, an increase in the incidence of obesity-related cancers has been reported. Multiple myeloma (MM) is the second most common hematological malignancy, after lymphoma. The aim of this review is to examine the epidemiological data on obesity and MM, assess the effect of obesity on MM outcomes, evaluate the possible mechanisms through which obesity might increase the incidence of MM and provide the effects of obesity management on MM. Current evidence indicates that obesity may have an impact on the progression of monoclonal gammopathy of undetermined significance (MGUS) to MM and increase the prevalence of MM. However, data regarding the effect of obesity on MGUS incidence are controversial; further studies are needed to examine whether obesity affects the development of MGUS or the progression of MGUS to MM. In addition, obesity affects MM outcomes. Increased BMI is associated with decreased survival in patients with MM, while data regarding the effect of obesity on newly diagnosed MM subjects and autologous stem cell transplantation are limited. Interestingly, the obesity paradox may also apply to patients with relapsed/refractory MM who are overweight or obese, because they may have a survival advantage. The pathophysiological pathways linking obesity to MM are very complicated and include bone marrow adipose tissue; adipokines, such as adiponectin, leptin, resistin, and visfatin; inflammatory cytokines and growth factors, such as TNF-α and IL-6; hormones including insulin and the insulin-like growth factor system as well as sex hormones. In terms of the effect of pharmacological management of obesity, orlistat has been shown to alter the proliferation of MM cells, whereas no data exist on glucagon-like peptide-1 receptor agonists, naltrexone/bupropion, or phentermine/topiramate. Bariatric surgery may be associated with a reduction in the incidence of MM, however, further studies are needed.

Recent Advances in the Knowledge of the Mechanisms of Leptin Physiology and Actions in Neurological and Metabolic Pathologies

Excess body weight is frequently associated with low-grade inflammation. Evidence indicates a relationship between obesity and cancer, as well as with other diseases, such as diabetes and non-alcoholic fatty liver disease, in which inflammation and the actions of various adipokines play a role in the pathological mechanisms involved in these disorders. Leptin is mainly produced by adipose tissue in proportion to fat stores, but it is also synthesized in other organs, where leptin receptors are expressed. This hormone performs numerous actions in the brain, mainly related to the control of energy homeostasis. It is also involved in neurogenesis and neuroprotection, and central leptin resistance is related to some neurological disorders, e.g., Parkinson's and Alzheimer's diseases. In peripheral tissues, leptin is implicated in the regulation of metabolism, as well as of bone density and muscle mass. All these actions can be affected by changes in leptin levels and the mechanisms associated with resistance to this hormone. This review will present recent advances in the molecular mechanisms of leptin action and their underlying roles in pathological situations, which may be of interest for revealing new approaches for the treatment of diseases where the actions of this adipokine might be compromised.

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.

Leptin induces leiomyoma cell proliferation and extracellular matrix deposition via JAK2/STAT3 and MAPK/ERK pathways

OBJECTIVE

To investigate the molecular effects of leptin on uterine leiomyoma cells.

DESIGN

Experimental study using in vitro culture of immortalized human leiomyoma (HuLM) cells.

SETTING

Academic university center.

PATIENT(S)

Women with uterine fibroids who underwent a hysterectomy or myomectomy.

INTERVENTION(S)

Administration of human recombinant leptin to the media of cultured HuLM cells separately or in combination with pharmacologic Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) or mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) inhibitors.

MAIN OUTCOME MEASURE(S)

We examined HuLM tissues and cells for the expression of the leptin receptor, termed OB-R. Cellular proliferation was measured at 6, 24, and 48 hours using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay. Protein expression levels of proliferating cell nuclear antigen, collagen 1, phosphorylated STAT3/total STAT3, and phosphorylated ERK1/2 and total ERK1/2 were quantified using immunoblotting. Pharmacologic inhibitors were employed to further assess the role of the JAK2/STAT3 and MAPK/ERK pathways in the proliferative response.

RESULT(S)

The presence of OB-R was confirmed in clinical leiomyoma and myometrial tissue obtained from 3 separate human subjects using immunofluorescence staining, and the expression of OB-R in HuLM cells was identified using immunoblotting. There was no significant difference in the expression of the leptin receptor in the myometrium compared with that in the leiomyoma tissue. Leptin stimulated cell proliferation and extracellular matrix (ECM) deposition at 24 hours after treatment. Pretreatment with a JAK2/STAT3 inhibitor attenuated ECM deposition, and pretreatment with a MAPK/ERK inhibitor significantly decreased leptin's stimulatory effect on cell proliferation and ECM deposition.

CONCLUSION(S)

Leptin induces a proliferative response and ECM deposition in HuLM cells. These findings suggest that leptin, acting through the JAK2/STAT3 and MAPK/ERK pathways, is involved in the development of uterine leiomyomas, which may partly explain their increased incidence in obese women.

The role of macrophage scavenger receptor 1 (MSR1) in inflammatory disorders and cancer

Macrophage scavenger receptor 1 (MSR1), also named CD204, holds key inflammatory roles in multiple pathophysiologic processes. Present primarily on the surface of various types of macrophage, this receptor variably affects processes such as atherosclerosis, innate and adaptive immunity, lung and liver disease, and more recently, cancer. As highlighted throughout this review, the role of MSR1 is often dichotomous, being either host protective or detrimental to the pathogenesis of disease. We will discuss the role of MSR1 in health and disease with a focus on the molecular mechanisms influencing MSR1 expression, how altered expression affects disease process and macrophage function, the limited cell signalling pathways discovered thus far, the emerging role of MSR1 in tumour associated macrophages as well as the therapeutic potential of targeting MSR1.

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.

Clusterin inhibits Cr(VI)-induced apoptosis via enhancing mitochondrial biogenesis through AKT-associated STAT3 activation in L02 hepatocytes

Improper treatment of a large amount of industrial waste makes hexavalent chromium [Cr(VI)] seriously pollute the atmosphere, soil and water, and enter the food chain, seriously affecting the health of workers and local residents. We previously proved that Clusterin (CLU) can inhibit the apoptosis of L02 hepatocytes induced by Cr(VI) through mitochondrial pathway, but the associated molecular mechanism has not been further studied. Mitochondrial biogenesis is an important step in mitochondrial damage repair, but the mechanism of mitochondrial biogenesis in Cr(VI)-induced liver toxicity is still unclear. We demonstrated in the present study that Cr(VI) triggered mitochondrial biogenesis dysfunction-associated apoptosis, and CLU delayed Cr(VI)-induced apoptosis by enhancing mitochondrial biogenesis. Signal transducer and activator of transcription 3 (STAT3) was down-regulated in Cr(VI)-induced apoptosis, and CLU may regulate STAT3 via protein kinase B (PKB/AKT) in Cr(VI)-exposed hepatocytes. We used the STAT3 inhibitor C188-9 and the AKT inhibitor Uprosertib to eliminate the anti-apoptotic effect of CLU, and found that CLU inhibited Cr(VI)-induced apoptosis by up-regulating AKT/STAT3 signal. Based on the fact that both AKT and STAT3 are closely related to mitochondrial biogenesis and mitochondrial pathway-associated apoptosis, this study is the first time to link CLU, STAT3, AKT and mitochondrial biogenesis function after Cr(VI) exposure, to further enrich the experimental basis of Cr(VI)-induced hepatotoxicity, clarify the molecular mechanism of CLU helping cells to escape apoptosis, and also suggest that new ways can be sought to prevent and treat Cr(VI)-induced hepatotoxicity by regulating mitochondrial biosynthesis.

Hyperleptinemia in obese state renders luminal breast cancers refractory to tamoxifen by coordinating a crosstalk between Med1, miR205 and ErbB

Obese women with hormone receptor-positive breast cancer exhibit poor response to therapy and inferior outcomes. However, the underlying molecular mechanisms by which obesity/hyperleptinemia may reduce the efficacy of hormonal therapy remain elusive. Obese mice with hyperleptinemia exhibit increased tumor progression and respond poorly to tamoxifen compared to non-obese mice. Exogenous leptin abrogates tamoxifen-mediated growth inhibition and potentiates breast tumor growth even in the presence of tamoxifen. Mechanistically, leptin induces nuclear translocation of phosphorylated-ER and increases the expression of ER-responsive genes, while reducing tamoxifen-mediated gene repression by abrogating tamoxifen-induced recruitment of corepressors NCoR, SMRT, and Mi2 and potentiating coactivator binding. Furthermore, in silico analysis revealed that coactivator Med1 potentially associates with 48 (out of 74) obesity-signature genes. Interestingly, leptin upregulates Med1 expression by decreasing miR-205, and increases its functional activation via phosphorylation, which is mediated by activation of Her2 and EGFR. It is important to note that Med1 silencing abrogates the negative effects of leptin on tamoxifen efficacy. In addition, honokiol or adiponectin treatment effectively inhibits leptin-induced Med1 expression and improves tamoxifen efficacy in hyperleptinemic state. These studies uncover the mechanistic insights how obese/hyperleptinemic state may contribute to poor response to tamoxifen implicating leptin-miR205-Med1 and leptin-Her2-EGFR-Med1 axes, and present bioactive compound honokiol and adipocytokine adiponectin as agents that can block leptin's negative effect on tamoxifen.

C-reactive protein as a diagnostic and prognostic factor of endometrial cancer

Endometrial cancer (EC) is the sixth most commonly occurring cancer in women and its morbidity and mortality are continuously increasing. Considering experience with different types of cancers, C-reactive protein (CRP) appears to be a promising diagnostic and prognostic factor. Aiming to investigate its potential in view of EC authors of this paper reviewed databases for metanalysis, randomized controlled trials and review articles. Studies indicate CRP > 3.33 mg/l correlates with the EC incidence with HR = 2.29 (p < 0.05). Moreover, High-sensitivity CRP assay allows to detect CRP in very low concentrations and distinguish patients with endometriosis, soft tissue sarcomas and possibly EC. Perioperational CRP, as well as its changes are independent prognostic factors for EC. However, CRP-to-albumin ratio as well as Glasgow Prognostic Score (GPS) have greater prognostic value that CRP alone. Additionally, CRP is possibly a mediator of carcinogenesis and cancer progression through activation of inter alia FcgRs/MAPK/ERK, FcgRs/IL-6/AKT/STAT3 and FcgRs/NF-κB/NLRP3 pathways.

Leptin expression is substantially correlated with prognosis of urinary bladder carcinoma

This study examined leptin expression in cases of bladder cancer and its diagnostic and prognostic usefulness in bladder malignancies.A set of 128 urinary bladder cancer cases and 24 normal specimens of bladders were employed for an immunohistochemical investigation of leptin expression in tissue microarrays.Leptin was up-regulated during transformation and was identified as brown cytoplasmic granules in the malignant urothelium of 123 (96%) bladder neoplasms, of which 68 (53.1%) cases showed high levels (moderate to strong) of staining. Strong staining was found to be associated with high stages (P = 0.001), muscularis propria infiltration (P < 0.001), vascular invasion (P < 0.03), lymph node involvement (P < 0.02), metastases (P < 0.05), and mortality (P < 0.03). Furthermore, various important survival distributions were detected with leptin expression in the malignant urothelium (P < 0.03).These pilot results suggest that leptin might be a valid marker for predicting the stage and bad prognoses in bladder carcinoma.

Cancer Risk in Normal Weight Individuals with Metabolic Obesity: A Narrative Review

Obesity represents one of the most significant public health challenges worldwide. Current clinical practice relies on body mass index (BMI) to define the obesity status of an individual, even though the index has long been recognized for its limitations as a measure of body fat. In normal BMI individuals, increased central adiposity has been associated with worse health outcomes, including increased risks of cardiovascular disease and metabolic disorders. The condition leading to these outcomes has been described as metabolic obesity in the normal weight (MONW). More recent evidence suggests that MONW is associated with increased risk of several obesity-related malignancies, including postmenopausal breast, endometrial, colorectal, and liver cancers. In MONW patients, the false reassurance of a normal range BMI can lead to lost opportunities for implementing preventive interventions that may benefit a substantial number of people. A growing body of literature has documented the increased risk profile of MONW individuals and demonstrated practical uses for body composition and biochemical analyses to identify this at-risk population. In this review, we survey the current literature on MONW and cancer, summarize pathophysiology and oncogenic mechanisms, highlight potential strategies for diagnosis and treatment, and suggest directions for future research.

Leptin and Cancer: Updated Functional Roles in Carcinogenesis, Therapeutic Niches, and Developments

Leptin is an obesity-associated adipokine that is known to regulate energy metabolism and reproduction and to control appetite via the leptin receptor. Recent work has identified specific cell types other than adipocytes that harbor leptin and leptin receptor expression, particularly in cancers and tumor microenvironments, and characterized the role of this signaling axis in cancer progression. Furthermore, the prognostic significance of leptin in various types of cancer and the ability to noninvasively detect leptin levels in serum samples have attracted attention for potential clinical applications. Emerging findings have demonstrated the direct and indirect biological effects of leptin in regulating cancer proliferation, metastasis, angiogenesis and chemoresistance, warranting the exploration of the underlying molecular mechanisms to develop a novel therapeutic strategy. In this review article, we summarize and integrate transcriptome and clinical data from cancer patients together with the recent findings related to the leptin signaling axis in the aforementioned malignant phenotypes. In addition, a comprehensive analysis of leptin and leptin receptor distribution in a pancancer panel and in individual cell types of specific organs at the single-cell level is presented, identifying those sites that are prone to leptin-mediated tumorigenesis. Our results shed light on the role of leptin in cancer and provide guidance and potential directions for further research for scientists in this field.

Identification of a Metabolism-Related Signature for the Prediction of Survival in Endometrial Cancer Patients

Objective

Endometrial cancer (EC) is one of the most common gynecologic malignancies. The present study aims to identify a metabolism-related biosignature for EC and explore the molecular immune-related mechanisms underlying the tumorigenesis of EC.

Methods

Transcriptomics and clinical data of EC were retrieved from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Common differentially expressed metabolism-related genes were extracted and a risk signature was identified by using the least absolute shrinkage and selection operator (LASSO) regression analysis method. A nomogram integrating the prognostic model and the clinicopathological characteristics was established and validated by a cohort of clinical EC patients. Furthermore, the immune and stromal scores were observed and the infiltration of immune cells in EC cells was analyzed.

Results

Six genes, including CA3, HNMT, PHGDH, CD38, PSAT1, and GPI, were selected for the development of the risk prediction model. The Kaplan-Meier curve indicated that patients in the low-risk group had considerably better overall survival (OS) (P = 7.874e-05). Then a nomogram was constructed and could accurately predict the OS (AUC = 0.827, 0.821, 0.845 at 3-, 5-, and 7-year of OS). External validation with clinical patients showed that patients with low risk scores had a longer OS (p = 0.04). Immune/stromal scores and infiltrating density of six types of immune cells were lower in high-risk group.

Conclusions

In summary, our work provided six potential metabolism-related biomarkers as well as a nomogram for the prognosis of EC patients, and explored the underlying mechanism involved in the progression of EC.

Leptin Receptor (LEPR) promotes proliferation, migration, and invasion and inhibits apoptosis in hepatocellular carcinoma by regulating ANXA7

Background

Leptin Receptor (LEPR) has been suggested to have several roles in cancer metastasis. However, the role of LEPR and its underlying mechanisms in lymphatic metastasis of hepatocarcinoma have not yet been studied.

Methods

We performed bioinformatics analysis, qRT-PCR, western blotting, immunohistochemistry, immunofluorescence, enzyme-linked immunosorbent, coimmunoprecipitation assays and a series of functional assays to investigate the roles of LEPR in hepatocellular carcinoma.

Results

We discovered that LEPR was highly expressed in liver cancer tissues, and the expression of LEPR in Hca-F cells was higher than that in Hca-P cells. Furthermore, LEPR promotes the proliferation, migration and invasion and inhibits the apoptosis of hepatocarcinoma lymphatic metastatic cells. Further studies indicated that LEPR interacts with ANXA7. Mechanistically, LEPR regulated ERK1/2 and JAK2/STAT3 expression via ANXA7 regulation.

Conclusions

These findings unveiled a previously unappreciated role of LEPR in the regulation of lymphatic metastatic hepatocellular carcinoma, assigning ANXA7-LEPR as a promising therapeutic target for liver cancer treatments.

Diabetes Mellitus and Obesity as Risk Factors for Bladder Cancer Prognosis: A Systematic Review and Meta-Analysis

BACKGROUND

Urinary bladder carcinoma is common in developed settings, and prognosis may be impacted by lifestyle factors such as excess body weight and diabetes mellitus. The present meta-analysis aimed to systematically collate and analyze evidence on the impact of diabetes and excess BMI on bladder cancer outcomes.

METHODS

PubMed, Scopus, and Google Scholar databases were screened for relevant studies that examined the association between bladder cancer outcomes and diabetes and/or excess body weight. The primary outcomes for this study were mortality (both all-cause and cancer-specific), risk of cancer progression, and recurrence. Strength of association was presented in the form of pooled adjusted hazard ratios (HR). Statistical analysis was performed using STATA version 16.0.

RESULTS

Twenty-five articles met inclusion criteria. Nine of these examined diabetes mellitus while 16 studied body mass index. All studies were retrospective. Diabetic patients had significantly higher risk for all-cause mortality (HR 1.24, 95% CI: 1.07, 1.44, n=3), cancer specific mortality (HR 1.67, 95% CI: 1.29, 2.16, n=7), disease progression (HR 1.54, 95% CI: 1.15, 2.06, n=8), and recurrence (HR 1.40, 95% CI: 1.32, 1.48, n=8) compared to non-diabetics. No statistically significant risk change for all-cause mortality, cancer specific mortality, disease progression, and recurrence was found for overweight patients. However, obese individuals were at higher risk for disease progression (HR 1.88, 95% CI: 1.41, 2.50, n=3) and recurrence (HR 1.60, 95% CI: 1.06, 2.40, n=7) compared to normal BMI patients.

CONCLUSIONS

These findings suggest that diabetes and excess body weight negatively influences bladder cancer prognosis and outcome. The increased risk of mortality due to diabetes was similar to that in the general population. Since retrospective studies are potentially susceptible to bias, future prospective studies on this subject are required.

New Actors Driving the Epithelial-Mesenchymal Transition in Cancer: The Role of Leptin

Leptin is a hormone secreted mainly by adipocytes; physiologically, it participates in the control of appetite and energy expenditure. However, it has also been linked to tumor progression in different epithelial cancers. In this review, we describe the effect of leptin on epithelial-mesenchymal transition (EMT) markers in different study models, including in vitro, in vivo, and patient studies and in various types of cancer, including breast, prostate, lung, and ovarian cancer. The different studies report that leptin promotes the expression of mesenchymal markers and a decrease in epithelial markers, in addition to promoting EMT-related processes such as cell migration and invasion and poor prognosis in patients with cancer. Finally, we report that leptin has the greatest biological relevance in EMT and tumor progression in breast, lung, prostate, esophageal, and ovarian cancer. This relationship could be due to the key role played by the enriched tumor microenvironment in adipose tissue. Together, these findings demonstrate that leptin is a key biomolecule that drives EMT and metastasis in cancer.

Leptin promotes proliferation of neonatal mouse stem/progenitor spermatogonia

PURPOSE

To keep and increase spermatogonial stem cell number (SSC) is the only available option for pediatric cancer survivors to maintain fertility. Leptin is secreted by the epididymal white adipose tissue and has receptors on stem/progenitor spermatogonia. The purpose of this study is to demonstrate dose- and time-dependent proliferative effect of leptin on stem/progenitor spermatogonia cultures from prepubertal mice testes.

METHODS

CD90.2 (+) stem/progenitor spermatogonia were isolated from the C57BL/6 mouse testis on postnatal day 6 and placed in culture. The proliferative effect of leptin supplementation was assessed by colony formation (diameter and number), WST proliferation assays, and xCELLigence real-time cell analysis (RTCA) on days 3, 5, and 7 of culture. Expressions of p-ERK1/2, p-STAT3, total STAT3, and p-SHP2 levels were determined by western blot analysis.

RESULTS

Leptin supplementation of 100 ng/ml increased the diameter (p = 0.001) and number (p = 0.01) of colonies in stem/progenitor spermatogonial cultures and caused higher proliferation by WST-1 (p = 0.009) compared with the control on day 7. The EC50 was calculated as 114 ng/ml for leptin by RTCA. Proliferative dose of leptin induced increased expression of p-ERK1/2 (p = 0.009) and p-STAT3 (p = 0.023) on stem/progenitor spermatogonia when compared with the untreated group.

CONCLUSION

The results indicated that leptin supplementation exhibited a dose- and time-dependent proliferative effect on stem/progenitor spermatogonia that was associated with increased expression of ERK1/2 and STAT3 pathways while maintaining their undifferentiated state. This output presents a new agent that may help to expand the stem/progenitor spermatogonia pool from the neonatal testis in order to autotransplant after cancer treatment.

The Impact of Hormonal Imbalances Associated with Obesity on the Incidence of Endometrial Cancer in Postmenopausal Women

Obesity has long been associated with endometrial cancer amongst postmenopausal women; in fact, obese women are more than twice as likely to develop endometrial cancer as women of normal weight. The risk of developing this type of cancer increases with weight gains in adulthood, especially among women who did not use hormonal therapy for menopause. Thus, with an association between menopause, obesity, and endometrial cancer established, it prompts the following question: what specific factors could cause higher risk levels for endometrial cancer in this cohort of women? In this paper, the factor of hormonal changes and imbalances associated with both obesity and menopause will be examined. The hormones that will be discussed are insulin and insulin-like factors, estrogen, and adipokines (specifically adiponectin, visfatin, and leptin).

Investigation of Leptin G19A polymorphism with bladder cancer risk: A case-control study

Background

A host of studies show Leptin (LEP) G19A polymorphism is correlated with the risk of various cancers, but the connection of this polymorphism with bladder cancer (BC) risk has not been reported.

Materials and methods

This association was in explored in a case‐control study involving 355 BC cases and 435 controls (all Chinese Han). Polymerase chain reaction‐restriction fragment length polymorphism was conducted to genotype LEP G19A polymorphism. Analyses of allele and genotype distribution were evaluated using chi‐square test. Continuous data were assessed by an independent samples t test or one‐way ANOVA test. Odds ratio (OR) and 95% confidence interval (CI) were determined by logistic regression.

Results

LEP G19A polymorphism was significantly associated with a lower risk of BC (AA vs GG: adjusted OR, 0.40, 95% CI, 0.20‐0.83, P = .013; AA + GA vs GG: adjusted OR, 0.70, 95% CI, 0.52‐0.93, P = .015; AA vs GA + GG: adjusted OR, 0.45, 95% CI, 0.22‐0.91, P = .026). In addition, A allele was associated with decreased risk for BC (A vs G: OR, 0.70, 95% CI, 0.55‐0.89, P = .003). Stratified analyses by females, non‐drinkers, and non‐smokers all returned considerable relations. Furthermore, LEP G19A polymorphism was correlated with tumor size, tumor node metastasis, and distant metastasis in BC patients.

Conclusions

LEP G19A polymorphism is associated with a less risk of BC.

The Possible Role of Adipokines in HCV Associated Hepatocellular Carcinoma

Background:

Adipokines play an important role in the regulation of inflammation and tumor progression.

Aim:

Assessment of the possible role of adiponectin, leptin and visfatin in HCV associated hepatocellular carcinoma (HCC).

Methods:

patients were classified into 85 patients with HCV associated HCC, 100 patients with chronic hepatitis C viral (HCV) infection compared to 50 normal control (NC) subjects. All subjects included in the study were assessed for HCV infection by seropositive HCV antibodies, as well as HCV RNA by RT-PCR. Serum levels of adiponectin, leptin and visfatin were assessed using enzyme linked immunosorbent assay (ELISA). The data were correlated to the relevant clinic-pathological features of the patients, and the overall survival (OS) rate.

Results:

There was a significant difference in the serum levels of adiponectin and visfatin among HCC, HCV and NC groups (P<0.001). The serum levels of leptin and alpha fetoprotein (AFP) were significantly higher in HCC group (P<0.001). There was a significant association between the serum level of adiponectin and advanced Child class liver cirrhosis (P=0.03), as well as with poor performance status (ECOG, P=0.02). Serum leptin associated significantly with the number of lesions in the liver (P=0.006), visfatin associated with increased mortality rate (P<0.001). Adiponectin, leptin and visfatin associated significantly with liver cirrhosis in HCV patients (P<0.01). Leptin achieved the highest sensitivity (98.8%). visfatin achieved the highest specificity (100%) and PPV (100%) for detection of HCC. The combination of serum leptin and visfatin for the diagnosis of HCV associated HCC showed sensitivity, specificity, PPV, NPV and accuracy (100%, 96.6%, 93.4%, 100% and 97.4%; respectively).

Conclusion:

Adiponectin, leptin and visfatin have an important role(s) in the pathogenesis of HCV associated HCC.

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.

Leptin receptor mediates the proliferation and glucose metabolism of pancreatic cancer cells via AKT pathway activation

Pancreatic cancer (PC) is the fourth leading cause of cancer‑related mortality worldwide. Leptin is an adipokine that is significantly increased in obese patients and that functions in various biological processes of cancer, such as tumor growth and metastasis. However, its role in PC cell proliferation and glucose metabolism and the underlying mechanisms remain unclear. In the present study, in vitro leptin treatment significantly promoted cell proliferation and increased glucose uptake and lactate production of human PC and healthy pancreas cells in a dose‑dependent manner, accompanied by increased expression of the glycolytic enzymes hexokinase II and glucose transporter 1. Furthermore, leptin receptor‑specific short hairpin RNAs were used to silence leptin receptor expression in PC cells, which had the opposite effect to leptin stimulation and decreased AKT phosphorylation. In addition, the effects of leptin stimulation were significantly counteracted by the AKT inhibitor LY294002, whereas the effects of leptin silencing were counteracted by AKT activator insulin‑like growth factor 1. The results of the present study suggested that leptin may contribute to cell proliferation and glucose metabolism of human PC cells, which may be through activation of the AKT pathway.

Gene expression changes and promoter methylation with the combined effects of estradiol and leptin in uterine tissue of the ovariectomized mice model of menopause

Substantial epidemiological studies have shown an association of obesity with the common gynecological malignancy, endometrial cancer. The relevant interactions and contribution of estradiol and the adipose cytokine, leptin, in endometrial lesions are not completely understood. Suitable animal models to understand the physiological response of uterine tissue to the combined effects of estradiol-leptin are lacking. To investigate the effect of estradiol-leptin crosstalk on gene expression and associated altered pathways, we established an ovariectomized mouse model, treated with 17-β estradiol (0.1 µg/mouse subcutaenously., for every 12 h) and/or recombinant mouse leptin (1 μg/g Bwt intraperitoneally., for every 12 h) for 4 h, 20 h, and 40 h. Gene expressions by semi-quantitative RT-PCR, uterine tissue protein phosphorylation status by western blotting and promoter methylation were analyzed in estradiol, progesterone insufficient animals. Semi-quantitative RT-PCR demonstrated significantly increased expression of Esr, Igf1, Igfbp3, Vegfr1, and Vegf, and significantly decreased expression of Mmp9 after co-treatment with estradiol and leptin, indicating a common transcriptional network regulated by the treatments. Ovariectomy-induced histomorphological changes were only reversed by estradiol. Methylation-specific PCR, analyzing methylation of CpG sites of Vegfa, Pgr, and Igf1, revealed that transcriptional regulation after hormonal treatments is independent of methylation at the examined CpG sites. Western blot confirmed the increased expression of PSTAT-3 (Ser-727) and PERK1/2 proteins after estradiol + leptin treatment, confirming the estradiol + leptin cross-talk hypothesis. In conclusion, our in vivo studies determined specific gene expression and signaling protein changes, and further unraveled the molecular targets of estradiol + leptin that may perturb endometrial homeostasis and lead to endometrial hyperplasia development in the chronic stimulated state.

Leptin-derived peptides block leptin-induced proliferation by reducing expression of pro-inflammatory genes in hepatocellular carcinoma cells

The obesity-regulated gene, leptin, is essential for diet. Leptin resistance causes obesity and related diseases. Certain types of diet are able to decrease leptin resistance. However, leptin has been shown to be correlated with inflammation and stimulate proliferation of various cancers. Two synthetic leptin derivatives (mimetics), OB3 and [D-Leu-4]-OB3, show more effective than leptin in reducing obesity and diabetes in mouse models. OB3 inhibits leptin-induced proliferation in ovarian cancer cells. However, effects of these mimetics in hepatocellular carcinoma (HCC) have not been investigated. In the present study, we examined the effects of OB3 and [D-Leu-4]-OB3 on cell proliferation and gene expressions in human HCC cell cultures. In contrast to what was reported for leptin, OB3 and [D-Leu-4]-OB3 reduced cell proliferation in hepatomas. Both OB3 and [D-Leu-4]-OB3 stimulated expression of pro-apoptotic genes. Both compounds also inhibited expressions of pro-inflammatory, proliferative and metastatic genes and PD-L1 expression. In combination with leptin, OB3 inhibited leptin-induced cell proliferation and expressions of pro-inflammation-, and proliferation-related genes. Furthermore, the OB3 peptide inhibited phosphoinositide 3-kinase (PI3K) activation which is essential for leptin-induced proliferation in HCC. These results indicate that OB3 and [D-Leu-4]-OB3 may have the potential to reduce leptin-related inflammation and proliferation in HCC cells.

Leptin-induced signaling pathways in cancer cell migration and invasion

BACKGROUND

Increasing evidence indicates that obesity is associated with tumor development and progression. Leptin is an adipocyte-related hormone with a key role in energy metabolism and whose circulating levels are elevated in obesity. The effect of leptin on cancer progression and metastasis and its underlying mechanisms are still unclear. Leptin can impact various steps in tumor metastasis, including epithelial-mesenchymal transition, cell adhesion to the extracellular matrix (ECM), and proteolysis of ECM components. To do so, leptin binds to its receptor (OB-Rb) to activate signaling pathways and downstream effectors that participate in tumor cell invasion as well as distant metastasis.

CONCLUSIONS

In this review, we describe metastasis steps in detail and characterize metastasis-related molecules activated by leptin, which may help to develop a roadmap that guides future work. In addition, we conclude that a profound understanding of the fundamental molecular processes that contribute to leptin-induced metastasis may pave the way for the development of new prognostic molecules and appropriate approaches to the treatment of obesity-related cancers.

The Expression of Leptin and Its Receptor During Tumorigenesis of Diffuse Gliomas such as Astrocytoma and Oligodendroglioma- Grade II, III and IV (NOS)

Background: Leptin, an adipocytokine functions via the leptin receptor, OB-Rb that contains an intact intracellular domain and activates the JAK/STAT signalling cascade. It stimulates growth, migration and invasion of cancer cells in vitro potentiating angiogenesis. Recently, the involvement of leptin in tumor progression is being explored. Gliomas exhibit poor prognosis, low survival rates demanding for novel therapeutic regimens resulting in discovery of many potential biomarkers and pharmaceutical targets. We analysed the potential role of leptin and OB-Rb in carcinogenesis of malignant gliomas. Methods: Sixty fresh tissue samples of diffuse gliomas were collected after tumor excision. Real time PCR, immunohistochemical (IHC) analysis and western blot analysis were carried out to assess the expression of leptin and its receptor. Results: The present study demonstrates the expression of leptin and LepR and their involvement in tumor progression. Of the 60 cases, 57 cases (95%) and 53 cases (88.3%) showed amplification for leptin and OB-Rb respectively. The expression of these proteins were measured semi-quantitatively and correlated with degree of malignancy (p<0.05). The bands were visualised on western blot. Conclusion: Leptin may be valued as a pharmaceutical target and anti-leptin compounds could be developed as drugs in mono- or combined therapies for these tumors.

Adipocyte-derived IL-6 and leptin promote breast Cancer metastasis via upregulation of Lysyl Hydroxylase-2 expression

BACKGROUND

Adipocytes make up the major component of breast tissue, accounting for 90% of stromal tissue. Thus, the crosstalk between adipocytes and breast cancer cells may play a critical role in cancer progression. Adipocyte-breast cancer interactions have been considered important for the promotion of breast cancer metastasis. However, the specific mechanisms underlying these interactions are unclear. In this study, we investigated the mechanisms of adipocyte-mediated breast cancer metastasis.

METHODS

Breast cancer cells were cocultured with mature adipocytes for migration and 3D matrix invasion assays. Next, lentivirus-mediated loss-of-function experiments were used to explore the function of lysyl hydroxylase (PLOD2) in breast cancer migration and adipocyte-dependent migration of breast cancer cells. The role of PLOD2 in breast cancer metastasis was further confirmed using orthotopic mammary fat pad xenografts in vivo. Clinical samples were used to confirm that PLOD2 expression is increased in tumor tissue and is associated with poor prognosis of breast cancer patients. Cells were treated with cytokines and pharmacological inhibitors in order to verify which adipokines were responsible for activation of PLOD2 expression and which signaling pathways were activated in vitro.

RESULTS

Gene expression profiling and Western blotting analyses revealed that PLOD2 was upregulated in breast cancer cells following coculture with adipocytes; this process was accompanied by enhanced breast cancer cell migration and invasion. Loss-of-function studies indicated that PLOD2 knockdown suppressed cell migration and disrupted the formation of actin stress fibers in breast cancer cells and abrogated the migration induced by following coculture with adipocytes. Moreover, experiments performed in orthotopic mammary fat pad xenografts showed that PLOD2 knockdown could reduce metastasis to the lung and liver. Further, high PLOD2 expression correlated with poor prognosis of breast cancer patients. Mechanistically, adipocyte-derived interleukin-6 (IL-6) and leptin may facilitate PLOD2 upregulation in breast cancer cells and promote breast cancer metastasis in tail vein metastasis assays. Further investigation revealed that adipocyte-derived IL-6 and leptin promoted PLOD2 expression through activation of the JAK/STAT3 and PI3K/AKT signaling pathways.

CONCLUSIONS

Our study reveals that adipocyte-derived IL-6 and leptin promote PLOD2 expression by activating the JAK/STAT3 and PI3K/AKT signaling pathways, thus promoting breast cancer metastasis.

Classic and Novel Adipocytokines at the Intersection of Obesity and Cancer: Diagnostic and Therapeutic Strategies

PURPOSE OF REVIEW

In this review, we investigate the role of classic and novel adipocytokines in cancer pathogenesis synopsizing the mechanisms underlying the association between adipocytokines and malignancy. Special emphasis is given on novel adipocytokines as new evidence is emerging regarding their entanglement in neoplastic development.

RECENT FINDINGS

Recent data have emphasized the role of the triad of overweight/obesity, insulin resistance and adipocytokines in cancer. In the setting of obesity, classic and novel adipocytokines present independent and joint effects on activation of major intracellular signaling pathways implicated in cell proliferation, expansion, survival, adhesion, invasion, and metastasis. Until now, more than 15 adipocytokines have been associated with cancer, and this list continues to expand. While the plethora of circulating pro-inflammatory adipocytokines, such as leptin, resistin, extracellular nicotinamide phosphoribosyl transferase, and chemerin are elevated in malignancies, some adipocytokines such as adiponectin and omentin-1 are generally decreased in cancers and are considered protective against carcinogenesis. Elucidating the intertwining of inflammation, cellular bioenergetics, and adiposopathy is significant for the development of preventive, diagnostic, and therapeutic strategies against cancer. Novel more effective and safe adipocytokine-centered therapeutic interventions may pave the way for targeted oncotherapy.

Leptin Regulation of Cancer Stem Cells in Breast and Gynecologic Cancer

It is well established that obesity increases the incidence and worsens the prognosis of women's cancer. For breast cancer, women with obesity exhibit more than a twofold increase in the odds of being diagnosed with cancer, with a greater risk of advanced stage at diagnosis, and ≤40% greater risk of recurrence and death than their normal-weight counterparts. These findings are similar in gynecologic cancers, where women who are obese with a body mass index (BMI) >40 kg/m2 have up to six times greater risk of developing endometrial cancer and a 9.2% increase in mortality with every 10% increase in BMI. Likewise, patients with obesity exhibit a twofold higher risk of premenopausal ovarian cancer, and patients who are obese with advanced stage ovarian cancer have shown a shorter time to recurrence and poorer overall survival. Obesity is accompanied by changes in expression of adipose factors that act on local tissues and systemically. Once obesity was recognized as a factor in cancer incidence and progression, the adipose cytokine (adipokine) leptin became the focus of intense investigation as a putative link, with nearly 3000 publications on the topic. Leptin has been shown to increase cell proliferation, inhibit apoptosis, promote angiogenesis, and increase therapeutic resistance. These characteristics are associated with a subset of cells in both liquid and solid tumors known as cancer stem cells (CSCs), or tumor initiating cells. We will review the literature discussing leptin's role in breast and gynecologic cancer, focusing on its role in CSCs, and consider goals for targeting future therapy in this arena to disrupt tumor initiation and progression in women's cancer.

The adipose organ and multiple myeloma: Impact of adipokines on tumor growth and potential sites for therapeutic intervention

In addition to its capacity to store lipids the adipose tissue is now identified as a real organ with both endocrine and metabolic roles. Preclinical results indicate that modifying adipose tissue and bone marrow adipose tissue (BMAT) could be a successful multiple myeloma (MM) therapy. BMAT interrelates with bone marrow cells and other immune cells, and may influence MM disease progression. The BM adipocytes may have a role in MM progression, bone homing, chemoresistance, and relapse, due to local endocrine, paracrine, or metabolic factors. BM adipocytes isolated from MM subjects have been shown to increase myeloma growth in vitro and may preserve cells from chemotherapy-induced apoptosis. By producing free fatty acids and emitting signaling molecules such as growth factors and adipokines, BM adipocytes are both an energy font and an endocrine signaling factory. This review should suggest future research approaches toward developing novel treatments to target MM by targeting BMAT and its products.

Gynaecological cancers and leptin: A focus on the endometrium and ovary

Obesity has an influence on the risk and prognosis of different types of cancers of the female reproductive tract. In the uterus, a common site for neoplasms is the endometrium, the inner lining tissue. Generally, obesity has been documented to be involved in endometrioid carcinoma of the endometrium. Obesity may influence the cancer risk by various mechanisms such as chronic inflammation, dysregulation of sex hormones and abnormal secretion of hormone-like cytokines or adipokines from adipose tissue. One of the important pro-inflammatory adipokines is leptin, which acts via its transmembrane receptors (Ob-R). In normal conditions, leptin functions in the hypothalamic anorexigenic pathway to maintain the energy homeostasis. Conversely, in obesity, leptin participates in the pro-inflammatory processes. Several clinical studies have suggested that leptin and Ob-R play a role in the pathological processes of endometrial cancer. In different endometrial cancer cell lines, laboratory findings also have demonstrated leptin's link to various neoplastic phenomena such as cellular proliferation, angiogenesis, and oestrogenic activity. Furthermore, endometrial cancer risk could be increased in ovarian pathology like polycystic ovary syndrome, which is commonly associated with obesity. It is noteworthy that leptin participates in both physiological and pathological conditions of the ovary. Leptin has shown pro-tumorigenic effects in both in-vitro and in-vivo studies. Generally, reduced serum leptin levels have been observed in ovarian cancer patients. However, overexpression of leptin and Ob-R in ovarian cancer tissue has indicated aggressive disease. Understanding the role of leptin-related intracellular signalling pathways in tumour development could be helpful in early cancer detection.

Molecular targets for the therapy of cancer associated with metabolic syndrome (transcription and growth factors)

Metabolic syndrome (MS) is one of the leading risk factors for the development of cardiovascular diseases, type II diabetes mellitus and reproductive system diseases. Currently, not only cardiovascular disease and reproductive history risks related with MS are frequently discussed, but it has been also shown that MS is associated with increased risk of some common cancers (endometrial cancer, postmenopausal breast cancer, colorectal cancer, biliary tract cancers and liver cancer for men). Further studies are required to understand the mechanisms of the involvement of MS components in the pathogenesis of malignant neoplasms. Changes in the expression of transcription and growth factors in the peripheral tissues as well as in cancer tissues of patients with MS were revealed. Transcription factors (AMP-activated protein kinase-1, STAT3, sterol regulatory element-binding protein-1 and peroxisome proliferator-activated receptor-γ), leptin and adiponectin receptors seem to be the most promising molecular targets for the therapy of cancers associated with MS.

Leptin induces matrix metalloproteinase 7 expression to promote ovarian cancer cell invasion by activating ERK and JNK pathways

Leptin, an adipokine secreted by adipose tissue, induces cell invasion and metastasis. MMP7 is a member of the matrix metalloproteinase family that plays an important role in cell invasion. Here we evaluate the possible role and underlying mechanism of MMP7 in the leptin-mediated cell invasion in ovarian cancer cell lines. All experiments were carried out in cultured SKOV3, OVCAR3, and CaoV-3 ovarian cell lines. MMP7 expression was determined using the Western blot following treatment to various concentrations of leptin for defined time intervals. The activation of ERK, JNK, and P38 MAP kinases were determined using Western blotting. Wound healing and BD matrigel invasion assays were used to measure cell migration and invasion. The siRNA approach and pharmacological inhibitors of ERK and JNK pathway were used to confirm the receptor-dependent effect of leptin and a role for ERK and JNK pathway. Zymography assay was employed to determine MMP2 and MMP9 activation. Results show that leptin induces ERK1/2 and JNK1/2 activation and subsequently promotes MMP7 expression in SKOV3 (4.8 ± 0.14 fold of control, P < 0.01) and OVCAR3 (3.1 ± 0.19 fold of control, P < 0.01) ovarian cancer cell lines. These effects was reversed by knockdown of OB-Rb and/or pre-incubation with PD98059 (ERK1/2 inhibitor), SP600125 (JNK1/2 inhibitor). Gelatin zymography showed that MMP7 gene silencing attenuated leptin-induced MMP9 activation in SKOV3 cell line. Taken together, our results suggest new evidences for a modulatory effect of leptin in regulation of ovarian cancer cell invasion by stimulating MMP7 expression via ERK and JNK pathways.

Superactive human leptin antagonist (SHLA), triple Lan1 and quadruple Lan2 leptin mutein as a promising treatment for human folliculoma

PURPOSE

There are no data showing a direct correlation between obesity and increased blood leptin levels with folliculoma. Moreover, folliculoma is not the best studied among other ovarian cancer types. We investigated whether oestradiol can modulate ObR expression in some oestrogen-responsive tissues and that leptin exerts its activity not only via the leptin receptor but also through cross talk with other signalling systems. We hypothesise that blocking ObR expression could be a novel treatment for gonadal ovarian cancer.

METHODS

We evaluated the effect of SHLA, Lan1 and Lan2 blockers on cell proliferation (BrdU incorporation assay), ObR and ERα/β gene expression (qPCR), oestradiol secretion (ELISA) and cell cycle protein expression (Western blot) in the non-cancerous cell line HGrC1 and two granulosa cancer cell lines: the juvenile form (COV434) and the adult form (KGN).

RESULTS

ObR gene expression in cancer cell lines was 50% higher than in the non-cancer cells. Lan-1 and Lan-2 decreased ObR expression in COV434, while it had no effect in KGN cells. Higher ERβ expression in non-cancer and higher ERα expression in both cancer cell lines was noted. SHLA and Lan-1 changed the ratio towards greater expression of ERβ, characteristic of non-cancer granulosa cells. All ObR antagonists in HCrC1 and KGN but only Lan-2 in COV434 reversed leptin-stimulated proliferation. In both non-cancer and cancer granulosa cells, leptin acts as a cyclinD/cdk4, cyclin A/cdk2 and E2F inhibitor.

CONCLUSION

These results indicate that SHLA and Lan2 are promising leptin receptor inhibitors that can eliminate the negative effects of leptin. These compounds should be considered in further ex vivo studies on the cancer microenvironment.

Leptin receptor signaling via Janus kinase 2/Signal transducer and activator of transcription 3 impacts on ovarian cancer cell phenotypes

Ovarian cancer is a leading cause of cancer mortality in women world-wide. Considerable progress has been made to characterize the different subtypes of ovarian cancer, but specific therapies remain limited and prognosis poor. Cytokine signaling via the interleukin-6 receptor (IL-6R) family and related receptors has been implicated in a number of cancers, including those with an ovarian origin. The leptin receptor (LEPR) is structurally related to these receptors and utilizes similar downstream pathways. LEPR has diverse roles in metabolism, appetite and bone formation with obesity linked to both elevated levels of leptin and increased cancer incidence. This study investigated a potential role for LEPR signaling in ovarian cancer. Leptin stimulation led to increased proliferation, survival and migration of LEPR-expressing ovarian cancer cell lines, with the effects shown to be mediated by the downstream Janus kinase 2/Signal transducer and activator of transcription 3 (JAK2/STAT3) pathway. A significant correlation was identified between high co-expression of leptin and LEPR and decreased patient survival. This study collectively suggests that leptin/LEPR signaling via JAK2/STAT3 has the potential to significantly impact on pathogenesis in a subset of ovarian cancer patients who may benefit from strategies that dampen this pathway.

Leptin signaling and cancer chemoresistance: Perspectives

Obesity is a major health problem and currently is endemic around the world. Obesity is a risk factor for several different types of cancer, significantly promoting cancer incidence, progression, poor prognosis and resistance to anti-cancer therapies. The study of this resistance is critical as development of chemoresistance is a serious drawback for the successful and effective drug-based treatments of cancer. There is increasing evidence that augmented adiposity can impact on chemotherapeutic treatment of cancer and the development of resistance to these treatments, particularly through one of its signature mediators, the adipokine leptin. Leptin is a pro-inflammatory, pro-angiogenic and pro-tumorigenic adipokine that has been implicated in many cancers promoting processes such as angiogenesis, metastasis, tumorigenesis and survival/resistance to apoptosis. Several possible mechanisms that could potentially be developed by cancer cells to elicit drug resistance have been suggested in the literature. Here, we summarize and discuss the current state of the literature on the role of obesity and leptin on chemoresistance, particularly as it relates to breast and pancreatic cancers. We focus on the role of leptin and its significance in possibly driving these proposed chemoresistance mechanisms, and examine its effects on cancer cell survival signals and expansion of the cancer stem cell sub-populations.

RhoA/ROCK pathway mediates leptin-induced uPA expression to promote cell invasion in ovarian cancer cells

Previous studies have shown that leptin, an adipocyte-secreted hormone, stimulates ovarian cancer invasion. Here, we investigated the contribution of uPA in leptin-induced ovarian cancer cell invasion. The cell invasion and migration experiments were carried out using matrigel invasion and wound healing assays in ovarian cancer cell lines (OVCAR3, SKOV3and CaoV-3). The mechanism underlying the invasive effect of leptin was examined using cell transfection with Ob-Rb siRNA, pre-treatment with a specific inhibitor of RhoA and ROCK, RhoA activation assay, OB-Rb, Rock and upA protein expression. Our results show that leptin induced ovarian cancer cell invasion via up-regulating upA in a time and dose-dependent manner, which was attenuated using knockdown of OB-Rb by siRNA. Moreover, pre-incubation with C3 (inhibitor of RhoA) and Y-27632 (inhibitor of ROCK) effectively attenuated leptin-induced upA expression and inhibited invasive ability of ovarian cancer cells. We also found that pretreatment with inhibitors of PI3K/AKT (LY294002), JAK/STAT (AG490) and NF-kB (BAY 11-7082) significantly reduced leptin-induced upA expression. Collectively, our findings demonstrate that OB-Rb, RhoA/ROCK, PI3K/AKT, JAK/STAT pathways and NF-kB activation are involved in leptin-induced upA expression. These results may provide a new mechanism that facilitates leptin-induced ovarian cancer invasion.