Prostate cancer cell proliferation is influenced by leptin

Globular adiponectin induces esophageal adenocarcinoma cell pyroptosis via the miR-378a-3p/UHRF1 axis

BACKGROUND

Antiapoptosis is a major factor in the resistance of tumor cells to chemotherapy and radiotherapy. Thus, activation of cell pyroptosis may be an effective option to deal with antiapoptotic cancers such as esophageal adenocarcinoma (EAC).

METHODS

Differential expression of ubiquitin-like versus PHD and ring finger structural domain 1 (UHRF1) in EAC and near normal tissues was analyzed, as well as the prognostic impact on survival in EAC. Also, the same study was done for globular adiponectin (gAD). Simultaneously, the mRNA expression of UHRF1 was observed in different EAC cell lines. Real time cellular analysis (RTCA) was used to detect cell proliferation, and flow cytometry and inverted fluorescence microscopy were used to detect pyroptosis. Biocredit analysis was conducted to observe the correlation between UHRF1 and key pyroptosis proteins. OD values and CCK8 assay were used to determine the effect of miR-378a-3p on EAC cells. Quantitative real-time polymerase chain reaction and Western blot were used to detect the correlation between UHRF1, gAD, and miR-378a-3p in EAC cells. Moreover, in vivo and in vitro experiments were performed to detect the relevant effects on tumor migration and invasion after inhibiting UHRF1 expression.

RESULTS

UHRF1 was negatively correlated with the survival of patients with EAC, while miR-378a-3p showed the opposite effect. Additionally, gAD promoted EAC cell pyroptosis, upregulated miR-378a-3p, and significantly inhibited the proliferation of EAC cells. gAD directly reduced UHRF1 expression in EAC cells by upregulating miR-378a-3p. In cell migration and invasion assays, inhibition of UHRF1 expression significantly suppressed EAC cell metastasis. In animal experiments, we again demonstrated that gAD induced pyroptosis in EAC cells by inhibiting the expression of UHRF1.

CONCLUSION

gAD-induced upregulation of miR-378a-3p significantly inhibited the proliferation of EAC by targeting UHRF1. Therefore, gAD may serve as an alternative therapy for chemotherapy- and radiation-refractory EAC or other cancers with the same mechanism of pyroptosis action.

Decoding the Influence of Obesity on Prostate Cancer and Its Transgenerational Impact

In recent decades, the escalating prevalence of metabolic disorders, notably obesity and being overweight, has emerged as a pressing concern in public health. Projections for the future indicate a continual upward trajectory in obesity rates, primarily attributable to unhealthy dietary patterns and sedentary lifestyles. The ramifications of obesity extend beyond its visible manifestations, intricately weaving a web of hormonal dysregulation, chronic inflammation, and oxidative stress. This nexus of factors holds particular significance in the context of carcinogenesis, notably in the case of prostate cancer (PCa), which is a pervasive malignancy and a leading cause of mortality among men. A compelling hypothesis arises from the perspective of transgenerational inheritance, wherein genetic and epigenetic imprints associated with obesity may wield influence over the development of PCa. This review proposes a comprehensive exploration of the nuanced mechanisms through which obesity disrupts prostate homeostasis and serves as a catalyst for PCa initiation. Additionally, it delves into the intriguing interplay between the transgenerational transmission of both obesity-related traits and the predisposition to PCa. Drawing insights from a spectrum of sources, ranging from in vitro and animal model research to human studies, this review endeavors to discuss the intricate connections between obesity and PCa. However, the landscape remains partially obscured as the current state of knowledge unveils only fragments of the complex mechanisms linking these phenomena. As research advances, unraveling the associated factors and underlying mechanisms promises to unveil novel avenues for understanding and potentially mitigating the nexus between obesity and the development of PCa.

Resistin stimulates PC-3 prostate cancer cell growth through stimulation of SOCS3 and SOCS5 genes

Resistin and suppressors of cytokine signaling (SOCSs) have been reported to regulate prostate cancer (PCa) cell proliferation and survival, respectively. Whether any of the SOCS molecules mediate the mitogenic effect of resistin on PCa cells is unknown. Using PC-3 human PCa cells, we found that resistin upregulates the expression of SOCS3 and SOCS5 mRNA, but not SOCS7 mRNA, in a dose- and time-dependent manner. The resistin-induced increases in SOCS3 and SOCS5 expression and cell proliferation were prevented by pretreatment with specific inhibitors of the TLR4, ERK, p38 MAPK, JNK, PI3K, and JAK2 proteins. However, pretreatment with a TLR2 inhibitor had no effect on resistin-mediated SOCS3 and SOCS5 expression. In addition, the effects of resistin on SOCS3, SOCS5, and SOCS7 mRNA levels were cell type-specific. Overexpression of either SOCS3 or SOCS5 enhanced further resistin-stimulated growth of PC-3 cells, whereas silencing SOCS3 or SOCS5 antagonized resistin-increased cell growth. Further PCa tissue analysis demonstrated higher levels of RETN, TLR4, SOCS3, and SOCS5 mRNAs in cancer tissues than benign prostate hyperplasia and indicated positive correlations among RETN, TLR4, and SOCS5. These data suggest that SOCS5, TLR4, and, to a lesser extent, SOCS3 can mediate the mitogenic effect of resistin on PC-3 PCa cells.

The altered levels of adiponectin - leptin as predictive biomarkers to estimate the severity of prostate cancer

Introduction and Aim: Prostate is one of the commonest sites of malignancy affecting elderly male population & is increasingly becoming a significant public health issue especially in countries having aging population. We hypothesized that altered levels of adiponectin-leptins may be an underlying connection between incidence of prostate cancer (PCa) and aged matched males.   Materials and Methods: This study was designed to comparatively corelate circulating serum levels of adiponectin & leptin in 160 elderly patients with PCa to their serum levels in 160 healthy controls. The age and body mass index in all groups were dissimilar in case and control. Based on the Gleason score of 7, =7 >7, patients were further subdivided into low, intermediate, high grades of PCa, respectively.    Results: No significant statistical variance was identified in terms of age, Body mass index (BMI), Radom blood glucose, HDL, LDL, triglycerides, total cholesterol, creatinine, and BUN levels within the compared groups. In PCa patients’ group, concentration levels of serum adiponectin were significantly lower, and levels of serum leptin was significantly greater compared to healthy controls (P<0.001). Statistical analysis revealed a significant positive inverse association between PSA and adiponectin levels (r=0.285, P<0.001) and significant association between serum levels of PSA and leptin (r=0.285, P<0.001). Significant statistical correlation was also evident between BMI, PSA, TG, and leptin were whole group. However, there was no significant association observed between adiponectin or leptin level and grade of the disease.   Conclusion: Evaluation of data in our study suggests that patients of PCa exhibit low concentration of serum adiponectin levels and high concentration of leptin levels. Further, this association was independent of histological grading of disease of disease/disease progression as well as other biochemical parameters.

Mechanistic Insights into the Link between Obesity and Prostate Cancer

Obesity is a pandemic of increasing worldwide prevalence. There is evidence of an association between obesity and the risk of prostate cancer from observational studies, and different biologic mechanisms have been proposed. The chronic low-level inflammation within the adipose tissue in obesity results in oxidative stress, activation of inflammatory cytokines, deregulation of adipokines signaling, and increased circulating levels of insulin and insulin-like growth factors (IGF). These mechanisms may be involved in epithelial to mesenchymal transformation into a malignant phenotype that promotes invasiveness, aggressiveness, and metastatic potential of prostate cancer. A thorough understanding of these mechanisms may be valuable in the development of effective prostate cancer prevention strategies and treatments. This review provides an overview of these mechanisms.

Circulating adiponectin and leptin and risk of overall and aggressive prostate cancer: a systematic review and meta-analysis

Obesity is associated with an increased risk of advanced, recurrent and fatal prostate cancer. Adipokines may mediate this relationship. We conducted a systematic review and meta-analysis of associations of leptin and adiponectin with overall and aggressive prostate cancer. Bibliographic databases were systematically searched up to 1st April 2017. Log Odds Ratios (ORs) per 2.5 unit increase in adiponectin or leptin levels were derived and pooled. All analyses were stratified by study type (cross-sectional/prospective). 746 papers were retrieved, 34 eligible studies identified, 31 of these could be included in the meta-analysis. Leptin was not consistently associated with overall prostate cancer (pooled OR 1.00, 95%CI 0.98-1.02, per 2.5 ng/ml increase, prospective study OR 0.97, 95%CI 0.95-0.99, cross-sectional study OR 1.19, 95%CI 1.13-1.26) and there was weak evidence of a positive association with aggressive disease (OR 1.03, 95%CI 1.00-1.06). There was also weak evidence of a small inverse association of adiponectin with overall prostate cancer (OR 0.96, 95%CI 0.93-0.99, per 2.5 µg/ml increase), but less evidence of an association with aggressive disease (OR 0.98, 95%CI 0.94-1.01). The magnitude of any effects are small, therefore levels of circulating adiponectin or leptin alone are unlikely to be useful biomarkers of risk or prognosis.

Assessment of expression levels of leptin and leptin receptor as potential biomarkers for risk of prostate cancer development and aggressiveness

Background

Prostate cancer (PCa) is one of the most frequently diagnosed cancers worldwide. Despite the growing evidence associating obesity and adipokines, particularly leptin and its receptors, with cancer development and progression, it is still a debatable matter in PCa.

Objectives

We aimed to assess the role of leptin and its receptors as potential biomarkers for the risk of PCa development and aggressiveness.

Methods

In this study, 176 men were included and categorized according to an established histopathological diagnosis into three age‐ and BMI‐matched groups. The PCa group included 56 patients while the BPH group and the control group comprised 60 men each. Serum levels of total PSA (tPSA) were assessed by ELISA and mRNA expression levels of leptin and leptin receptors were assessed by RT‐PCR.

Results

Leptin and leptin receptor mRNA expression levels were significantly higher in PCa patients relative to BPH and to healthy control men. Both were overexpressed in PCa patients with aggressive and distantly metastasizing tumors compared to patients with confined tumors. Leptin receptor mRNA was an independent predictor of high Gleason score ≥ 7, distant metastasis, LN, and seminal vesicles invasion.

Conclusion

Leptin and its receptors are suggested to be potential biomarkers for PCa; leptin receptor mRNA might predict risk and aggressiveness of PCa.

Analysis of Transcriptome, Selected Intracellular Signaling Pathways, Proliferation and Apoptosis of LNCaP Cells Exposed to High Leptin Concentrations

Leptin, the first discovered adipokine, has been connected to various physiological and pathophysiological processes, including cancerogenesis. Increasing evidence confirms its influence on prostate cancer cells. However, studies on the effects of leptin on the proliferation and apoptosis of the androgen-sensitive LNCaP line of prostate cancer cells brought conflicting results. Therefore, we performed studies on the effects of high LEP concentration (1 × 10⁻⁶ M) on gene expression profile, change of selected signaling pathways, proliferation and apoptosis of LNCaP cells. RTCA (real-time cell analyzer) revealed inhibitory effect of LEP on cell proliferation, but lower LEP concentrations (10⁻⁸ and 10⁻¹⁰ M) did not affect cell division. Moreover, flow cytometry with a specific antibody for Cleaved PARP-1, an apoptosis marker, confirmed the activation of apoptosis in leptin-exposed LNCaP line of prostate cancer cells. Within 24 h LEP (10⁻⁶ M) increases expression of 297 genes and decreases expression of 119 genes. Differentially expressed genes (DEGs) were subjected to functional annotation and clusterization using the DAVID bioinformatics tools. Most ontological groups are associated with proliferation and apoptosis (seven groups), immune response (six) and extracellular matrix (two). These results were confirmed by the Gene Set Enrichment Analysis (GSEA). The leptin’s effect on apoptosis stimulation was also confirmed using Pathview library. These results were also confirmed by qPCR method. The results of Western Blot analysis (exposure to LEP 10 min, 1, 2, 4 and 24 h) suggest (after 24 h) decrease of p38 MAPK, p44-42 mitogen-activated protein kinase and Bcl-2 phosphorylated at threonine 56. Moreover, exposure of LNCaP cells to LEP significantly stimulates the secretion of matrix metallopeptidase 7 (MMP7). Obtained results suggest activation of apoptotic processes in LNCaP cells cultured at high LEP concentration. At the same time, this activation is accompanied by inhibition of proliferation of the tested cells.

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.

Molecular Mechanisms of Cancer-Induced Sleep Disruption

Sleep is essential for health. Indeed, poor sleep is consistently linked to the development of systemic disease, including depression, metabolic syndrome, and cognitive impairments. Further evidence has accumulated suggesting the role of sleep in cancer initiation and progression (primarily breast cancer). Indeed, patients with cancer and cancer survivors frequently experience poor sleep, manifesting as insomnia, circadian misalignment, hypersomnia, somnolence syndrome, hot flushes, and nightmares. These problems are associated with a reduction in the patients' quality of life and increased mortality. Due to the heterogeneity among cancers, treatment regimens, patient populations and lifestyle factors, the etiology of cancer-induced sleep disruption is largely unknown. Here, we discuss recent advances in understanding the pathways linking cancer and the brain and how this leads to altered sleep patterns. We describe a conceptual framework where tumors disrupt normal homeostatic processes, resulting in aberrant changes in physiology and behavior that are detrimental to health. Finally, we discuss how this knowledge can be leveraged to develop novel therapeutic approaches for cancer-associated sleep disruption, with special emphasis on host-tumor interactions.

Glucose impairments and insulin resistance in prostate cancer: the role of obesity, nutrition and exercise

BACKGROUND

Hyperinsulinemia, obesity and related metabolic diseases are associated with prostate cancer development. Prostate cancer patients undergoing androgen deprivation therapy (ADT) are at increased risk for metabolic syndrome, cardiovascular disease and diabetes, while pre-existing metabolic conditions may be exacerbated.

PURPOSE

An integrative approach is used to describe the interactions between insulin, glucose metabolism, obesity and prostate cancer. The potential role of nutrition and exercise will also be examined.

FINDINGS

Hyperinsulinemia is associated with prostate cancer development, progression and aggressiveness. Prostate cancer patients who undergo ADT are at risk of diabetes in survivorship. It is unclear whether this is a direct result of treatment or related to pre-existing metabolic features (e.g. hyperinsulinemia and obesity). Obesity and metabolic syndrome are also associated with prostate cancer development and poorer outcomes for cancer survivors, which may be driven by hyperinsulinemia, pro-inflammation, hyperleptinemia and/or hypoadiponectinemia.

CONCLUSIONS

Independently evaluating changes in glucose metabolism near the time of prostate cancer diagnosis and during long-term ADT treatment is important to distinguish their unique contributions to the development of metabolic disturbances. Integrative approaches, including metabolic, clinical and body composition measures, are needed to understand the role of adiposity and insulin resistance in prostate cancer and to develop effective nutrition and exercise interventions to improve secondary diseases in survivorship.

Leptin promotes the growth of breast cancer by upregulating the Wnt/β-catenin pathway

The present study aimed to investigate the role of leptin in the growth of breast cancer. In the present study, expression of leptin in tumor tissues and adjacent tissues was detected by reverse transcription-quantitative polymerase chain reaction. Serum leptin in patients with breast cancer and normal healthy controls was detected by ELISA. Different concentrations of leptin were used to treat breast cancer cells, and cell proliferation was detected by cell proliferation assay. Interactions between leptin and Wnt/β-catenin were evaluated by western blotting. It was demonstrated that expression of leptin mRNA was significantly higher in tumor tissues than in adjacent tissues in 43 out of 48 patients. Serum level of leptin was significantly higher in patients with breast cancer than in normal controls. Leptin promoted the proliferation of breast cancer cells in a dose-dependent manner. Leptin significantly increased the expression level of β-catenin in breast cancer cells. Treatment with Wnt inhibitor reduced the enhancing effects of leptin on proliferation of breast cancer cells. The results of the present study therefore indicate that leptin may promote the growth of breast cancer by upregulating the Wnt/β-catenin pathway.

Targeting the leptin receptor: To evaluate therapeutic efficacy and anti-tumor effects of Doxil, in vitro and in vivo in mice bearing C26 colon carcinoma tumor

Leptin is an appetite regulatory hormone that is secreted into the blood circulation by the adipose tissue and it functions via its over expressed receptors (Ob-R) in a wide variety of cancers. In the present study, the function of a leptin-derived peptide (LP16, 91-110 of Leptin) was investigated as a targeting ligand to decorate PEGylated liposomal doxorubicin (PLD, Doxil^®) surface and the anti-tumor activity and therapeutic efficacy of Doxil in C26 (Colon Carcinoma) tumor model were also evaluated. As a result of this, Doxil with different LP16 peptide density (25, 50, 100 and 200 peptide on the surface of each liposome) was successfully prepared and characterized. In vitro results showed significant enhanced cytotoxicity and cellular binding and uptake of LP16-targeted Doxil formulations (LP16-Doxil) in C26 cells as compared to Doxil. In BALB/c mice bearing C26 murine carcinoma, at a dose of 15 mg/kg, LP16-Doxil groups (100 ligand) significantly suppressed the growth of the tumor and showed higher inclination to tumor as compared to non-targeted Doxil. This study revealed that the potential of LP16 peptide targeting increased the therapeutic efficacy of Doxil and highlighted the importance of optimizing the ligand density to maximize the targeting ability of the nanocarriers and merits further investigations.

Clinical Significance of Serum Adipokines according to Body Mass Index in Patients with Clinically Localized Prostate Cancer Undergoing Radical Prostatectomy

PURPOSE

The aim of this study was to investigate the clinical significance of 7 circulating adipokines according to body mass index (BMI) in Korean men with localized prostate cancer (PCa) undergoing radical prostatectomy (RP).

MATERIALS AND METHODS

Sixty-two of 65 prospectively enrolled patients with clinically localized PCa who underwent RP between 2015 and 2016 were evaluated. Patients were classified into 2 groups according to their BMI: non-obese (<25 kg/m²) and obese (≥25 kg/m²). The adipokines evaluated were interleukin-2, insulin-like growth factor 1 (IGF-1), chemerin, C-X-C motif chemokine 10, adiponectin, leptin, and resistin. Multivariate logistic regression analysis was used to identify the independent predictors of advanced tumor stage.

RESULTS

We found that obese patients with PCa who underwent RP had a higher incidence of tumors with a high Gleason score (≥8), pathological T3 (pT3) stage, and positive extraprostatic extension than patients with a normal BMI. Additionally, patients with obesity showed significantly lower serum adiponectin and higher serum leptin levels, but did not show differences in other adipokines. Multivariate analysis demonstrated that IGF-1 (odds ratio [OR]=1.03) was identified as a predictor of advanced tumor stage (≥pT3) in the overall population. However, only leptin remained an independent predictive factor for advanced tumor stage (≥pT3) (OR=1.15) in patients with obesity.

CONCLUSIONS

In conclusion, our results indicate that a higher leptin level in obese men can be considered a risk factor for aggressive PCa. This prospective study provides greater insight into the role of circulating adipokines in Korean patients with PCa undergoing RP, particularly in patients with obesity.

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.

Does obesity modify prostate cancer detection in a European cohort?

INTRODUCTION

To investigate prostate-specific antigen (PSA) accuracy and digital rectal examination (DRE) accuracy in detecting prostate cancer according to body mass index (BMI) in Spanish men with an indication of the first prostate biopsy.

MATERIAL AND METHODS

We reviewed the clinical and histopathological data of 1,319 patients who underwent transrectal ultrasound-guided prostate needle biopsy. The patients were categorised according to the BMI as follows: <25 kg/m² (normal weight); 25-29.9 kg/m² (overweight); and ≥30 kg/m² (obese). Receiver operator characteristic curves were used to assess PSA accuracy and DRE accuracy by calculating the area under the curve.

RESULTS

The obesity rate of the cohort was 14%. PSA accuracy for predicting prostate cancer in each BMI category was 0.52, 0.58 and 0.62, respectively (p = 0.01). After stratification by DRE findings, there was no difference in the performance accuracy of PSA in predicting the presence of cancer across BMI groups in abnormal DRE (p = 0.90). Serum PSA, DRE and BMI were strong predictors of prostate cancer diagnosis (odds ratio 1.07, 2.02 and 1.4, respectively; p <0.001). When the DRE was abnormal, a BMI ≥30 increased the risk of prostate cancer twice. With the addition of BMI to the model, the area under the curve of the combined PSA and DRE for diagnosing prostate cancer improved from 0.60 to 0.63.

CONCLUSIONS

The predictive value of PSA in predicting prostate cancer is not poorer in the obese population and the predictive value of an abnormal DRE in cancer detection is significantly modified by the patient's BMI.

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.

Globular adiponectin inhibits leptin-stimulated esophageal adenocarcinoma cell proliferation via adiponectin receptor 2-mediated suppression of UHRF1

Esophageal adenocarcinoma (EAC) is one of the most common malignancies in the world which is associated the increased prevalence of obesity. In the context of obesity, leptin can directly contribute to progression of EAC. Adiponectin inhibits leptin-induced oncogenic signaling in EAC cells. However, the exact molecular mechanisms linking obesity, adipokines, and EAC remain far from completely understood. In the present study, we tested the role of ubiquitin-like with PHD and ring finger domains 1 (UHRF1) in adiponectin-induced protective effects against leptin-induced EAC cell proliferation. We found that globular adiponectin (gAD) significantly inhibited leptin-induced increase of cell proliferation and decrease of apoptosis in OE 19 cells. Moreover, leptin-induced increase of UHRF1 expression was suppressed by gAD. Compared with normal controls, UHRF1 expression was markedly increased in EAC tissues and cell lines. Silence of UHRF1 increased the expression of cleaved caspase 3 and 9 and Bax, reduced the expression of Bcl-2, promoted apoptosis, and inhibited cell proliferation in OE 19 cells. Overexpression of UHRF1 significantly blocked gAD-induced decrease of cell proliferation and increase of apoptosis in leptin-treated cells. Silence of adiponectin receptor 1/2 (AdipoR1/2) could inhibit gAD-induced decrease of cell proliferation and increase of apoptosis in leptin-treated cells. Silence of AdipoR2, but not AdipoR1, suppressed gAD-induced decrease of UHRF1 expression in leptin-treated cells. The results indicated that gAD inhibited the prooncogenic effects of leptin via AdipoR2-mediated suppression of UHRF1. Our study provides novel insights into the role of UHRF1 in the development of EAC and the mechanism of antitumor effect of gAD.

Waist-hip Ratio (WHR), a Better Predictor for Prostate Cancer than Body Mass Index (BMI): Results from a Chinese Hospital-based Biopsy Cohort

To investigate whether waist-hip ratio (WHR) is a better predictor of prostate cancer (PCa) incidence than body mass index (BMI) in Chinese men. Of consecutive patients who underwent prostate biopsies in one tertiary center between 2013 and 2015, we examined data on 1018 with PSA ≤20 ng/ml. Clinical data and biopsy outcomes were collected. Logistic regression was used to evaluate the associations between BMI, WHR and PCa incidence. Area under the ROC (AUC) was used to evaluate the accuracy of different prognostic models. A total of 255 men and 103 men were diagnosed with PCa and high grade PCa (HGPCa, Gleason score ≥8). WHR was an independent risk factor for both PCa (OR = 1.07 95%Cl 1.03-1.11) and HGPCa (OR = 1.14 95%Cl 1.09-1.19) detection, while BMI had no relationship with either PCa or HGPCa detection. Adding WHR to a multivariable model increased the AUC for detecting HGPCa from 0.66 (95%Cl 0.60-0.72) to 0.71 (95%Cl 0.65-0.76). In this Chinese cohort, WHR was significantly predictive of PCa and HGPCa. Adding WHR to a multivariable model increased the diagnostic accuracy for detecting HGPCa. If confirmed, including WHR measurement may improve PCa and HGPCa detection.

The emerging role of obesity, diet and lipid metabolism in prostate cancer

Obesity is associated with an increased risk of a number of serious medical conditions, including cancer. As far as prostate cancer is concerned, obesity is associated with an increased risk of high-grade tumors, which is possibly related to lower androgen levels. Diet may also affect prostate cancer risk since countries with a higher dietary fat intake also present higher prostate cancer mortality rates. Interestingly, prostate cancer is associated with a number of metabolic alterations that may provide valuable diagnostic and therapeutic targets. This review explores the available clinical as well as biological evidence supporting the relationship between obesity, diet, alteration in metabolic pathways and prostate cancer.

The molecular mechanism of action of superactive human leptin antagonist (SHLA) and quadruple leptin mutein Lan-2 on human ovarian epithelial cell lines

Introduction

A number of leptin receptor antagonists have been synthesised for therapeutic use, with pre-clinical tests suggesting their future use in anticancer therapy. To our knowledge, there are no data concerning the possible application of leptin receptor blockers in ovarian cancer.

Methods

In this study, we evaluated two leptin receptor antagonists: superactive human leptin antagonist (SHLA) and quadruple leptin mutein, Lan-2 (L39A/D40A/F41A/I42A), on cell proliferation (Alamar Blue test, BrdU assay), cell cycle gene (qPCR) and protein expression (Western blot) and cell signalling pathways (Western blot) in three different types of cell lines: OVCAR-3, CaOV-3 and HOSEpiC.

Results

Both receptor blockers had no effect on non-cancerous HOSEpiC cell line proliferation; however, both reversed the stimulatory effect of leptin on CaOV-3 cell line proliferation to control levels and to below control levels in OVCAR-3 cells. In metastatic carcinoma CaOV-3, both ObR antagonists had an inhibitory effect on the cdk2/cyclin D1 complex, while in serous carcinoma, OVCAR-3, they only had an effect on cdk2 and cdk4 protein expression. SHLA had an inhibitory effect on all investigated signalling pathways in OVCAR-3, while only on Stat3 in CaOV-3. Lan-2 had an inhibitory effect on Stat3 and ERK1/2 in CaOV-3, while in OVCAR-3 it only affected Akt protein phosphorylation.

Conclusion

Based on these results, we conclude that SHLA and Lan-2 are promising leptin receptor inhibitors which could be used to block leptin activity, eliminating its negative effects on activities related to carcinogenesis. However, the selection of a specific antagonist should be related to tumour type.

Leptin serves as angiogenic/mitogenic factor in melanoma tumor growth

Background:

Tumor development is angiogenesis dependent. There is evidence that leptin contributes to tumor growth. However, all the mechanisms by which leptin does this has not been clearly established. The objective of the present study was to test the hypothesis that leptin enhances melanoma tumor growth through inducing angiogenesis and cell proliferation.

Materials and Methods:

We injected 2 × 10⁶ B16F10 melanoma cells subcutaneously to 32 C57BL6 mice. The mice were randomly divided into four groups of eight animals, on day 8. Two groups received twice daily intraperitoneal (i.p.) injections of either phosphate buffered saline or recombinant murine leptin (1 μg/g initial body weight). Two groups received i.p. injections of either 9F8 an anti leptin receptor antibody or the control mouse IgG at 50 μg/injection every 3 consecutive days. By the end of the 2^nd week, the animals were euthanized and blood samples and tumors were analyzed. Angiogenesis and proliferation were assessed by immunohistochemical staining for CD31 and Ki-67 respectively.

Results:

Tumors size, capillary density, plasma levels of vascular endothelial growth factor, and the number of Ki-67-positive stained cells were significantly more in the leptin than 9F8 and both control groups (P < 0.05).

Conclusion:

Taken together, our findings reinforce the idea that leptin acts as an angiogenic and mitogenic factor to promote melanoma growth.

Adipocytes enhance murine pancreatic cancer growth via a hepatocyte growth factor (HGF)-mediated mechanism

INTRODUCTION

Obesity accelerates the development and progression of pancreatic cancer, though the mechanisms underlying this association are unclear. Adipocytes are biologically active, producing factors such as hepatocyte growth factor (HGF) that may influence tumor progression. We therefore sought to test the hypothesis that adipocyte-secreted factors including HGF accelerate pancreatic cancer cell proliferation.

MATERIAL AND METHODS

Murine pancreatic cancer cells (Pan02 and TGP-47) were grown in a) conditioned medium (CM) from murine F442A preadipocytes, b) HGF-knockdown preadipocyte CM, c) recombinant murine HGF at increasing doses, and d) CM plus HGF-receptor (c-met) inhibitor. Cell proliferation was measured using the MTT assay. ANOVA and t-test were applied; p < 0.05 considered significant.

RESULTS

Wild-type preadipocyte CM accelerated Pan02 and TGP-47 cell proliferation relative to control (59 ± 12% and 34 ± 12%, p < 0.01, respectively). Knockdown of preadipocyte HGF resulted in attenuated proliferation vs. wild type CM in Pan02 cells (35 ± 5% vs. 68 ± 14% greater than control; p < 0.05), but proliferation in TGP-47 cells remained unchanged. Recombinant HGF dose-dependently increased Pan02, but not TGP-47, proliferation (p < 0.05). Inhibition of HGF receptor, c-met, resulted in attenuated proliferation versus control in Pan02 cells, but not TGP-47 cells.

CONCLUSIONS

These experiments demonstrate that adipocyte-derived factors accelerate murine pancreatic cancer proliferation. In the case of Pan02 cells, HGF is responsible, in part, for this proliferation.

Metabolic syndrome diagnosis and widespread high grade prostatic intraepithelial neoplasia significantly increase prostate cancer risk: results from a multicenter biopsy study

Background

To test in multicenter setting if patients affected of metabolic syndrome (MetS) and initial widespread high grade prostatic intraepithelial neoplasia (wHGPIN) diagnosis are at higher risk of prostate cancer (PCa) on repeat biopsy.

Methods

Patients clinical charts from three European Academic Hospital were reviewed in order to identify patients with initial diagnosis of HGPIN undergone to repeat biopsy. Inclusion and exclusion criteria were adopted to minimize patient heterogeneity. MetS was defined according to Word Heart Organization criteria while initial wHGPIN when ≥4 cores biopsy were involved. A multivariate logistic model was computed to assess the association between PCa and clinical-pathological variables.

Results

Overall 283 patients were scheduled. Median age was 67 years (IQR 62–72). MetS was diagnosed in 116/283 (41 %) patients and PCa was detected in 84/283 (29.7 %) patients.

In particular, PCa was more frequently diagnosed in patients affected of wHGPIN and MetS (45/86, 52.3 %) than in patients with wHGPIN and normal metabolic profile (28/95, 29.5 %), p = 0.002. The multivariate logistic model confirmed that wHGPIN and MetS are independent risk factors for following PCa diagnosis, respectively OR 2.4 (95 % CI 1.01–5.71, p = 0.04), OR 2.79 (95 % CI 1.49–5.22, p = 0.01) while total PSA and DRE findings are not able to predict PCa at repeat biopsy, OR 1.05 (95 % CI 0.98–1.03 p = 0.69) and OR 1.01 (95 % CI 0.55–1.84, p = 0.96) respectively.

Conclusions

wHGPIN is positively associated to PCa; assessing metabolic profile and repeat prostate biopsy is advisable in patients with initial diagnosis of wHGPIN.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2085-8) contains supplementary material, which is available to authorized users.

Diabetes-associated dysregulated cytokines and cancer

Epidemiological data demonstrate that patients with diabetes have an augmented risk of developing various types of cancers, accompanied by higher mortality. A number of mechanisms for this connection have been hypothesized, such as insulin resistance, hyperinsulinemia, hyperglycemia, and increased inflammatory processes. Apart from these potential mechanisms, several diabetes-associated dysregulated cytokines might be implicated in the link between diabetes and cancer. In fact, some inflammatory cytokines, e.g. TNF-α, IL-6 and leptin, have been revealed to play important roles in both initiation and progression of tumor. Here, we depict the role of these cytokines in key events of carcinogenesis and cancer development, including their capability to induce oxidative stress, inflammation, their participation in epithelial mesenchymal transition (EMT), angiogenesis, and metastasis. Finally, we will also highlight the existing knowledge in terms of the involvement of these cytokines in different cancer types and comment on potential significances for future clinical applications.

Leptin Promotes cPLA₂ Gene Expression through Activation of the MAPK/NF-κB/p300 Cascade

Hyperplasia or hypertrophy of adipose tissues plays a crucial role in obesity, which is accompanied by the release of leptin. Recently, obesity was determined to be associated with various pulmonary diseases including asthma, acute lung injury, and chronic obstructive pulmonary disease. However, how obesity contributes to pulmonary diseases and whether leptin directly regulates lung inflammation remains unclear. We used cell and animal models to study the mechanisms of leptin mediation of pulmonary inflammation. We found that leptin activated de novo synthesis of cytosolic phospholipase A₂-α (cPLA₂-α) in vitro in the lung alveolar type II cells, A549, and in vivo in ICR mice. Upregulated cPLA₂-α protein was attenuated by pretreatment with an OB-R blocking antibody, U0126, SB202190, SP600125, Bay11-7086, garcinol, and p300 siRNA, suggesting roles of p42/p44 MAPK, p38 MAPK, JNK1/2, NF-κB, and p300 in leptin effects. Leptin enhanced the activities of p42/p44 MAPK, p38 MAPK, JNK1/2, and p65 NF-κB in a time-dependent manner. Additional studies have suggested the participation of OB-R, p42/p44 MAPK, and JNK1/2 in leptin-increased p65 phosphorylation. Furthermore, p300 phosphorylation and histone H4 acetylation were reduced by blockage of OB-R, p42/p44 MAPK, p38 MAPK, JNK1/2, and NF-κB in leptin-stimulated cells. Similarly, blockage of the MAPKs/NF-κB/p300 cascade significantly inhibited leptin-mediated cPLA₂-α mRNA expression. Our data as a whole showed that leptin contributed to lung cPLA₂-α expression through OB-R-dependent activation of the MAPKs/NF-κB/p300 cascade.

Adipocyte-derived monocyte chemotactic protein-1 (MCP-1) promotes prostate cancer progression through the induction of MMP-2 activity

BACKGROUND

Obesity is known to be associated with prostate cancer development and progression, but the detailed mechanism is not clear. Monocyte chemotactic protein-1 (MCP-1) is secreted from cancer cells, stromal cells, and adipocytes, and it is involved in prostate cancer progression. Here we investigated the biological role of MCP-1 secreted from adipocytes for prostate cancer cells.

METHODS

Human pre-adipocytes (HPAds) were cultured and differentiated to mature adipocytes. Conditioned medium (CM) from HPAd cells was obtained using phenol red-free RPMI1640 medium. We performed a cytokine membrane array analysis to detect cytokines in the CM. To characterize the physiological function of MCP-1 in the CM, we performed an MTT-assay, a wound-healing and invasion assay with anti-MCP-1 antibody using three prostate cancer cell lines: DU145, LNCaP, and PC-3. Matrix metalloproteinase (MMP)-2 and MMP-9 activities were evaluated by gelatin zymography. A qPCR and Western blotting were used to examine the mRNA and protein expression levels of MMP-2.

RESULTS

The cytokine membrane array of the CM showed a strong signal of MCP-1compared to the control medium, and we thus focused our attention on MCP-1 in the CM. The CM up-regulated the cancer cell proliferation, and the neutralization by anti-MCP-1 antibody inhibited the proliferative effect of the prostate cancer cell lines. The CM greatly increased the invasive activity in the prostate cancer cell lines, and anti-MCP-1 antibody decreased the invasiveness. Gelatin zymography revealed that the CM markedly enhanced the enzymatic activity of MMP-2, and anti-MCP-1 antibody down-regulated its effect. MMP-2 mRNA expression was undetected and the MMP-2 protein level was unchanged between the control medium and CM in DU145 cells.

CONCLUSIONS

MCP-1 from adipocytes enhances the growth and invasion activity of prostate cancer cells. The inhibition of MCP-1 derived from adipocytes might be an effective treatment for prostate cancer.

Leptin activation of mTOR pathway in intestinal epithelial cell triggers lipid droplet formation, cytokine production and increased cell proliferation

Accumulating evidence suggests that obesity and enhanced inflammatory reactions are predisposing conditions for developing colon cancer. Obesity is associated with high levels of circulating leptin. Leptin is an adipocytokine that is secreted by adipose tissue and modulates immune response and inflammation. Lipid droplets (LD) are organelles involved in lipid metabolism and production of inflammatory mediators, and increased numbers of LD were observed in human colon cancer. Leptin induces the formation of LD in macrophages in a PI3K/mTOR pathway-dependent manner. Moreover, the mTOR is a serine/threonine kinase that plays a key role in cellular growth and is frequently altered in tumors. We therefore investigated the role of leptin in the modulation of mTOR pathway and regulation of lipid metabolism and inflammatory phenotype in intestinal epithelial cells (IEC-6 cells). We show that leptin promotes a dose- and time-dependent enhancement of LD formation. The biogenesis of LD was accompanied by enhanced CXCL1/CINC-1, CCL2/MCP-1 and TGF-β production and increased COX-2 expression in these cells. We demonstrated that leptin-induced increased phosphorylation of STAT3 and AKT and a dose and time-dependent mTORC activation with enhanced phosphorilation of the downstream protein P70S6K protein. Pre-treatment with rapamycin significantly inhibited leptin effects in LD formation, COX-2 and TGF-β production in IEC-6 cells. Moreover, leptin was able to stimulate the proliferation of epithelial cells on a mTOR-dependent manner. We conclude that leptin regulates lipid metabolism, cytokine production and proliferation of intestinal cells through a mechanism largely dependent on activation of the mTOR pathway, thus suggesting that leptin-induced mTOR activation may contribute to the obesity-related enhanced susceptibility to colon carcinoma.

Leptin exerts proliferative and anti-apoptotic effects on goose granulosa cells through the PI3K/Akt/mTOR signaling pathway

Leptin was known as a pivotal regulator for the control of food intake and energy expenditure. However, leptin has also been found to be involved in the regulation of female reproductive system through interactions with pathways in the hypothalamic-hypophyseal axis and direct action at the ovarian level. In the present study, granulosa cells from goose ovarian preovulatory (F1-F3) follicles were cultured with leptin (0, 1, 10 or 100ng/ml). The proliferative and anti-apoptotic actions of leptin in granulosa cells were revealed by CCK-8, BrdU and TUNEL assays. Quantitative real-time PCR and Western blot analyses further indicated that leptin treatment led to increased expression of cyclin D1, cyclin D2, cyclin D3 and bcl-2, and decreased expression of p21 and caspase-3. The effects were involved in the activation of the PI3K/Akt/mTOR signaling pathway, as leptin treatment enhanced the expression of PI3K, Akt1, Akt2, Raptor, mTOR, S6K and p-S6K. Moreover, blockade of the PI3K/Akt/mTOR pathway attenuated the influences of leptin on proliferation and apoptosis of granulosa cells, considering that activated factors by leptin were inhibited in the presence of either 20μM LY294002 (a PI3K inhibitor) or 10μM rapamycin (an mTOR inhibitor). In addition, leptin had a modulatory effect on the expression of its receptor at the transcriptional and translational levels, and blockade of PI3K/Akt/mTOR inhibited both basal and leptin-induced Lepr gene and protein expression. These findings suggest that leptin exerts its proliferative and anti-apoptotic effects on goose granulosa cells through the PI3K/Akt/mTOR signaling pathway via interaction with its receptor.

Long‑term exposure to leptin enhances the growth of prostate cancer cells

Obesity correlates with an increased risk of developing prostate cancer (PCa) and leptin plays an important role in PCa progression. Since leptin is produced by adipocytes, the serum leptin level is higher in obese than in non-obese individuals. However, the effects of leptin remain controversial and unclear. The aim of the present study was to investigate the effect of leptin on PCa cell aggressiveness. Three human PCa cell lines (LNCaP, DU145 and PC-3) were treated with recombinant leptin for 28 days. Cell proliferation, migration, and invasion were estimated using the WST assay, a wound-healing assay, and a BD Matrigel invasion assay, respectively. The mechanism underlying the proliferative effect of leptin was investigated by cell transfections with small interfering RNA (siRNA) against the leptin receptor (ObR) or forkhead box O1 (FOXO1), and by immunocytochemistry. Long-term exposure of PCa cells to leptin enhanced their proliferation, migration and invasion. Leptin increased ObR expression and enhanced Akt phosphorylation constitutively. Leptin also increased the phosphorylation of FOXO1 via PI3K signaling and FOXO1 gene silencing enhanced PCa cell proliferation. Leptin induced the translocation of FOXO1 from the nucleus to the cytoplasm. Furthermore, the PI3K inhibitor, LY294002 suppressed this translocation. These results suggested that leptin regulated the subcellular localization of FOXO1 and induced Akt phosphorylation. Additionally, we revealed that leptin increased the expression of cyclin D1 and decreased the expression of p21 protein. In conclusion, long-term exposure to leptin increased the cell proliferation, migration, and invasion of PCa cells through inactivation of FOXO1. This inactivation resulted from exclusion of FOXO1 from the nucleus and its restriction to the cytoplasm through PI3K/Akt signaling. Our findings contribute to an understanding of the association between obesity and PCa aggressiveness.

Leptin influences estrogen metabolism and accelerates prostate cell proliferation

AIM

The present study was designed to investigate the effect of leptin on estrogen metabolism in prostatic cells.

MAIN METHODS

Malignant (PC-3) and benign (BPH-1) human prostate cells were treated with 17-β-hydroxyestradiol (1 μM) alone or in combination with leptin (0.4, 4, 40 ng/ml) for 72 h. Cell proliferation assay, immunocytochemical staining of estrogen receptor (ER), liquid chromatography-tandem mass spectrometry method (LC-MS) and semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) were used.

KEY FINDINGS

Cell proliferation assay demonstrated that leptin caused significant growth potentiation in both cells. Immunocytochemical staining showed that leptin significantly increased the expression of ER-α and decreased that of ER-β in PC-3 cells. LC-MS method revealed that leptin increased the concentration 4-hydroxyestrone and/or decreased that of 2-methoxyestradiol, 4-methoxyestradiol and 2-methoxyestrone. Interestingly, RT-PCR showed that leptin significantly up-regulated the expression of aromatase and cytochrome P450 1B1 (CYP1B1) enzymes; however down-regulated the expression of catechol-o-methyltransferase (COMT) enzyme.

SIGNIFICANCE

These data indicate that leptin-induced proliferative effect in prostate cells might be partly attributed to estrogen metabolism. Thus, leptin might be a novel target for therapeutic intervention in prostatic disorders.

Obesity induced rapid melanoma progression is reversed by orlistat treatment and dietary intervention: role of adipokines

Obesity, owing to adiposity, is associated with increased risk and development of various cancers, and linked to their rapid growth as well as progression. Although a few studies have attempted to understand the relationship between obesity and melanoma, the consequences of controlling body weight by reducing adiposity on cancer progression is not well understood. By employing animal models of obesity, we report that controlling obesity either by orlistat treatment or by restricting caloric intake significantly slows down melanoma progression. The diminished tumor progression was correlated with decreased fat mass (adiposity) in obese mice. Obesity associated factors contributing to tumor progression were decreased in the experimental groups compared to respective controls. In tumors, protein levels of fatty acid synthase (FASN), caveolin (Cav)-1 and pAkt, which are tumor promoting molecules implicated in melanoma growth under obese state, were decreased. In addition, increased necrosis and reduction in angiogenesis as well as proliferative markers PCNA and cyclin D1 were observed in tumors of the orlistat treated and/or calorically restricted obese mice. We observed that growth of melanoma cells cultured in conditioned medium (CM) from orlistat-treated adipocytes was reduced. Adipokines (leptin and resistin), via activating Akt and modulation of FASN as well as Cav-1 respectively, enhanced melanoma cell growth and proliferation. Together, we demonstrate that controlling body weight reduces adipose mass thereby diminishing melanoma progression. Therefore, strategic means of controlling obesity by reduced caloric diet or with antiobesity drugs treatment may render obesity-promoted tumor progression in check and prolong survival of patients.

Is periprostatic adipose tissue associated with aggressive tumor biology in prostate cancer?

The prevalence of overweight and obesity and their health-related problems have been increasing. Obesity is increasingly recognized as a risk factor in different types of cancer in humans. The mechanisms supporting the link between obesity and cancer development have not been fully understood. Leptin, a circulating cytokine produced by adipocytes, may influence prostate cancer (PCa) progression in different ways. Body mass index seems to be an unreliable predictor for the development of PCa, but its influence on progression and poor oncological outcomes seems to be clear. Given the fact that abdominal fat is the most metabolically active fat, with different metabolic and paracrine effects, related anthropometric measurements may lead to a better estimation of PCa risk. Metabolically active periprostatic abdominal fat may also play an important role in releasing cytokines and growth factors that may promote tumor cell proliferation or even create a favorable environment for aggressive tumor biology. Different imaging measurements, e.g., periprostatic adipose tissue (PPAT) thickness, may be significant predictors of PCa. Several genes in the PPAT of obese men have been identified to contribute to chronic immuno-inflammatory responses which eventually lead to cell cycle alteration with oncological potential. In vitro studies showed the importance of PCa and its interaction with its microenvironment particularly in patients with aggressive PCa. Different types of cytokines, such as interleukin-6, may promote a tumorigenic microenvironment. This article endeavors to review the current literature on the association of PPAT with aggressive tumor biology in PCa.

Exogenous fatty acid binding protein 4 promotes human prostate cancer cell progression

Epidemiologic studies have found that obesity is associated with malignant grade and mortality in prostate cancer. Several adipokines have been implicated as putative mediating factors between obesity and prostate cancer. Fatty acid binding protein 4 (FABP4), a member of the cytoplasmic fatty acid binding protein multigene family, was recently identified as a novel adipokine. Although FABP4 is released from adipocytes and mean circulating concentrations of FABP4 are linked with obesity, effects of exogenous FABP4 on prostate cancer progression are unclear. In this study, we examined the effects of exogenous FABP4 on human prostate cancer cell progression. FABP4 treatment promoted serum-induced prostate cancer cell invasion in vitro. Furthermore, oleic acid promoted prostate cancer cell invasion only if FABP4 was present in the medium. These promoting effects were reduced by FABP4 inhibitor, which inhibits FABP4 binding to fatty acids. Immunostaining for FABP4 showed that exogenous FABP4 was taken up into DU145 cells in three-dimensional culture. In mice, treatment with FABP4 inhibitor reduced the subcutaneous growth and lung metastasis of prostate cancer cells. Immunohistochemical analysis showed that the number of apoptotic cells, positive for cleaved caspase-3 and cleaved PARP, was increased in subcutaneous tumors of FABP4 inhibitor-treated mice, as compared with control mice. These results suggest that exogenous FABP4 might promote human prostate cancer cell progression by binding with fatty acids. Additionally, exogenous FABP4 activated the PI3K/Akt pathway, independently of binding to fatty acids. Thus, FABP4 might be a key molecule to understand the mechanisms underlying the obesity-prostate cancer progression link.

Leptin-induced adhesion and invasion in colorectal cancer cell lines

Leptin, which is encoded by the obese gene, is a multifunctional neuroendocrine peptide that regulates appetite, bone formation, reproductive function and angiogenesis. The aims of the present study were to investigate the expression of leptin in 80 patients with colorectal cancer (CRC) and to determine the effects of leptin on the malignant properties of CRC cells. We evaluated the expression of leptin in tissues of 80 patients with CRC. Suspension cultures were used to isolate CRC stem cells following pretreatment with leptin. We analyzed the effects of leptin on the adhesion and invasive capacities of CRC cell lines. The effects of leptin on JAK and ERK activation were examined using western blotting. Leptin expression was associated with CRC progression and increased the number and size of spheroid formation by CRC cell lines. Leptin enhanced cell invasion and adhesion and activated JAK and ERK signaling in the CRC cell lines. The present study demonstrated that leptin influences the growth and survival of CRC stem cells and regulates adhesion and invasion of colorectal carcinoma through activation of the JAK and ERK signaling pathways.

Periprostatic adipose tissue from obese prostate cancer patients promotes tumor and endothelial cell proliferation: a functional and MR imaging pilot study

BACKGROUND

Obesity, particularly visceral adiposity, confers a worse prognosis for prostate cancer (PCa) patients, and increasing periprostatic adipose (PPA) tissue thickness or density is positively associated with more aggressive disease. However, the cellular mechanism of this activity remains unclear. Therefore, in this pilot study, we assessed the functional activity of PPA tissue secretions and established a biochemical profile of PPA as compared to subcutaneous adipose (SQA) tissues from lean, overweight and obese PCa patients.

METHODS

Adipose tissues were collected from PCa patients undergoing surgical prostate removal. Tissues were analyzed by histologic and magnetic resonance (MR) techniques. Explant tissue culture secretions were used in proliferation assays on PCa and endothelial cells.

RESULTS

PPA secretions obtained from obese patients were significantly more pro-proliferative in both PCa and endothelial cells as compared to PPA obtained from lean or overweight men and SQA tissues. Consistent with this, PPA microvessel density was increased, and the T2 relaxation time was decreased, compared to SQA tissues, and we observed a modest, inverse correlation between the T2 and tumor stage. Moreover, the ratio of unsaturated to saturated fatty acids, obtained using MR spectroscopy, showed a modest, inverse correlation with Gleason score.

CONCLUSIONS

These pilot data show that PPA stimulates PCa cell proliferation and angiogenesis and that obesity intensifies this activity, thus generating a mechanistic hypothesis to explain the worse prognosis observed in obese PCa patients. Our pilot study also shows that MR technology may be useful in further elucidating the relationship between obesity and PCa progression.

Role of the interleukin 6 receptor family in epithelial ovarian cancer and its clinical implications

Ovarian cancer is the most lethal gynecological malignancy, with few effective treatment options in most cases. Therefore, understanding the biology of ovarian cancer remains an important area of research in order to improve clinical outcomes. Cytokine receptor signaling through the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway is an essential component of normal development and homeostasis. However, numerous studies have implicated perturbation of this pathway in a range of cancers. In particular, members of the IL-6R family acting via the downstream STAT3 transcription factor play an important role in a number of solid tumors - including ovarian cancer - by altering the expression of target genes that impact on key phenotypes. This has led to the development of specific inhibitors of this pathway which are being used in combination with standard chemotherapeutic agents. This review focuses on the role of IL-6R family members in the etiology of epithelial ovarian cancer, and the application of therapies specifically targeting IL-6R signaling in this disease setting.

Exercise effects on adipokines and the IGF axis in men with prostate cancer treated with androgen deprivation: A randomized study

BACKGROUND

Androgen deprivation therapy (ADT) has significant deleterious effects on body composition that may be accompanied by unfavourable changes in adipokine levels. While exercise has been shown to improve a number of side effects associated with ADT for prostate cancer, no studies have assessed the effect of exercise on adiponectin and leptin levels, which have been shown to alter the mitogenic environment.

METHODS

Twenty-six men with prostate cancer treated with ADT were randomized to home-based aerobic exercise training or resistance exercise training for 24 weeks. Adiponectin, leptin, insulin-like growth factor 1 (IGF-1), insulin-like growth factor binding protein 3 (IGFBP-3) were analyzed by ELISA (enzyme-linked immunosorbent assay), in addition to physical activity volume, peak aerobic capacity, and anthropometric measurements, at baseline, 3 months and 6 months.

RESULTS

Resistance exercise significantly reduced IGF-1 after 3 months (p = 0.019); however, this change was not maintained at 6 months. At 6 months, IGFBP-3 was significantly increased compared to baseline for the resistance training group (p = 0.044). In an exploratory analysis of all exercisers, favourable changes in body composition and aerobic fitness were correlated with favourable levels of leptin, and favourable leptin:adiponectin and IGF-1:IGFBP-3 ratios at 3 and 6 months.

CONCLUSIONS

Home-based exercise is correlated with positive changes in adipokine levels and the IGF-axis that may be related to healthy changes in physical fitness and body composition. While the improvements of adipokine markers appear to be more apparent with resistance training compared to aerobic exercise, these findings must be considered cautiously and require replication from larger randomized controlled trials to clarify the role of exercise on adipokines and IGF-axis proteins for men with prostate cancer.

Leptin promotes the proliferation and migration of human breast cancer through the extracellular-signal regulated kinase pathway

Obesity has been associated with an increased risk of postmenopausal breast cancer, which may be due to the expression of leptin. The aim of this study was to determine the role of leptin in the growth of breast cancer cells in nude mice, the proliferation and migration of MCF-7 human breast cancer cells and its downstream signaling pathway. The xenograft mouse model was elicited by injecting MCF-7 human breast cancer cells into the left back axilla and the tumor size was measured every other day. Leptin injected subcutaneously around the tumor site led to an increase in the size and weight of the tumor, whereas the leptin antagonist (LA) significantly inhibited the size and weight of the tumor. Leptin promoted the proliferation and migration of MCF-7 cells and LA inhibited it. The effects of leptin on increasing the size and weight of the tumor in the nude mice and the proliferation and migration of MCF-7 human breast cancer cells were eradicated by pretreatment with LA, the extracellular-signal regulated kinase (ERK) inhibitor PD98059. In the xenograft mouse model the leptin level was increased and leptin increased the phosphorylation of ERK in the MCF-7 cells, whereas LA significantly reduced the phosphorylation of ERK. These results indicated that leptin promotes the growth of breast cancer in the nude mice and increases the proliferation and migration of MCF-7 human breast cancer cells via the ERK pathway.

Leptin enhances the invasive ability of glioma stem-like cells depending on leptin receptor expression

Glioma stem-like cells have been demonstrated to have highly invasive activity, which is the major cause of glioma recurrence after therapy. Leptin plays a role in glioma invasion, however, whether and how leptin contributes to the biological properties of glioma stem-like cells, such as invasion, remains to be explored. In the current study, we aimed to explore the role of leptin during glioma stem-like cells invasion as well as the signaling pathway. We found that glioma stem-like cells exhibited high invasive potential, especially in the presence of leptin, Ob-R coexpressed with CD133 in glioma stem-like cells was showed to be responsible for leptin mediated invasion of glioma stem-like cells. Our results indicated that leptin served as a key intermediary linking the accumulation of excess adipokine to the invasion of glioma stem-like cells, which may be a novel therapeutic target for suppressing tumor invasion and recurrence.

Obesity and prostate cancer incidence and mortality: a systematic review of prospective cohort studies

BACKGROUND

There has been a large body of research on obesity and the risk of prostate cancer (PCa) that has been published recently. However, the epidemiological evidence for such an association has not been consistent. This may be attributed to the nature of case-control and retrospective studies, which generally are more prone to biases. Therefore, we conducted a systematic review of prospective cohort studies to assess the association between obesity and the risk of PCa incidence and death.

METHODS

A search of the PubMed database and references of published studies (from inception until March 2013) was conducted. Twenty-three eligible studies were identified and included in the systematic review.

RESULTS

The evidence from the prospective cohort studies linking obesity with PCa incidence has not been consistent. However, cumulative data is compelling for a strong positive association between obesity and fatal PCa.

CONCLUSIONS

Obesity is a significant diet-related risk factor for fatal PCa. Further well-constructed, large cohort studies on the potential association between obesity and PCa, as well as on underlying mechanisms, are needed.

Role of adipocytokines and its correlation with endocrine pancreatic function in patients with pancreatic cancer

INTRODUCTION

Some authors suggest that adipocytokines contribute to the induction of pancreatic carcinogenesis as well as the development of endocrine insufficiency.

AIMS

We evaluate the circulating concentrations of leptin, resistin and visfatin in patients with newly diagnosed pancreatic cancer (PC) and relationship between serum adipocytokines level and clinicopathological features of PC. Moreover the usefulness of those adipocytokines as possible biomarkers of endocrine pancreatic function in PC has been assessed.

METHODS

The pilot study group consisted of 45 individuals (mean age 65.6 ± 11.5 years, BMI 21.8 ± 3.4 kg/m(2)) with newly diagnosed PC (within last 1-3 months) and 13 healthy individuals with age, gender and BMI matched to the study group. Among PC patients 18 (40%) had recently diagnosed diabetes. Fasting plasma leptin, resistin, visfatin concentrations were determined with ELISA (R&D Systems, Phoenix Pharmaceuticals) and insulin by RIA (DakoCytomation).

RESULTS

Patients with PC as compared to controls had significantly lower plasma leptin (40.6 ± 21.3 vs 63.2 ± 16.3 pg/mL; p < 0,0008). In contrast PC patients showed more than six fold higher level of resistin (126.2 ± 143.2 vs 18.9 ± 7.2 ng/mL; p < 0.009) than controls. The median plasma visfatin was 2.8 ± 1.8 ng/mL, which was not significantly different from the controls (3.8 ± 1.1 ng/mL). When PC patients with and without diabetes were considered separately, plasma leptin concentrations among nondiabetic patients were slightly, but not significantly higher (44.6 ± 21.0) as compared to diabetics (34.5 ± 20.7). Moreover there was no difference between visfatin and resistin level in PC, among patients with and without diabetes. No significant differences between serum level of leptin, visfatin and resistin and age, gender, BMI, smoking status, tumor localization, distant metastases and pain has been found.

CONCLUSION

The results of this study confirm previous findings that patients with newly diagnosed pancreatic cancer are characterized with lower level of leptin. This pilot study showed significantly higher resistin concentrations in patients with PC in comparison to healthy controls, which may be helpful in PC early diagnosis. Changes in leptin and resistin level in PC are not likely related to endocrine disorders.

Effects of dietary high fat on prostate intraepithelial neoplasia in TRAMP mice

Increased fat intake is known to be a major cause of prostate cancer. In this study, we investigated the effect of dietary high fat on prostate intraepithelial neoplasia using transgenic adenocarcinoma mouse prostate (TRAMP) mice. Six-week-old male TRAMP mice were fed AIN93G (control group, 4.0 kcal/kg, n=6) and AIN93G-HFD (experimental group, 4.8 kcal/kg, n=7) for 10 weeks. Prostate histopathology, urogenital tract (UGT) weight, epididymal white adipose tissue weight, argyrophilic nucleolar organizer regions (AgNORs) counts, and serum leptin levels were examined. AIN93G-HFD fed group showed progressed neoplastic lesions in the prostate (P<0.05) compared to AIN93G fed group. AIN93G-HFD intake resulted in a increase in the weight of UGT (P<0.05) and epididymal white adipose tissue. The number of Ag-NOR positive dots significantly increased in each prostate lobe and final serum leptin levels in AIN93G-HFD fed group were about twice those of AIN93G fed group (P<0.05). Dietary high fat was related to the prostate cancer progression in the early stage of TRAMP mice and increased serum leptin levels, suggesting that the regulation of dietary components could delay the progression of prostate cancer.

Female heterozygous (+/fa) Zucker rats as a novel leptin-related mammary carcinogenesis model

The homozygous mutant fatty Zucker rat (fa/fa) is the prominent model for the research of obesity, one of the most well-known risk factor of postmenopausal mammary cancer. But the usage as a mammary gland carcinogenesis model is considered to be restricted due to the hypoplasia of mammary gland. In the present study, to find the validity of heterozygous mutant (+/fa) lean Zucker rats as a new leptin-related mammary carcinogenesis model, we examined whether the number of terminal end buds of mammary gland, the serum biochemistry, leptin concentration in serum and adipose tissue are changed in 7-week-old female +/+, +/fa and fa/fa rats, and whether these changes and leptin, TNF-α and VEGF mRNA expression in adipose tissue of +/+ and +/fa rats are influenced by 10% corn oil diet for 5 weeks. We confirmed that mild hyperleptinemia was more pronounced in 7-week-old +/fa as compared with wild type (+/+) and hypoplasia of mammary glands characterized by fewer numbers of terminal end buds in fa/fa was not observed in +/fa. With 10% corn oil diet, leptin mRNA expression in adipose tissue showed increasing tendency both in +/fa and +/+. Comparing with +/+, adipose tissue in +/fa treated with 10% corn oil diet was found to be significantly increased in the concentration of leptin protein and tended to be elevated expression of TNF-α mRNA. These results suggest that +/fa with 10% corn oil diet may be a useful model for investigation of the participation of leptin and TNF-α in mammary gland carcinogenesis.

Leptin stimulates ovarian cancer cell growth and inhibits apoptosis by increasing cyclin D1 and Mcl-1 expression via the activation of the MEK/ERK1/2 and PI3K/Akt signaling pathways

Obesity is known to be an important risk factor for many types of cancer, such as breast, prostate, liver and endometrial cancer. Recently, epidemiological studies have indicated that obesity correlates with an increased risk of developing ovarian cancer, the most lethal gynecological cancer in developed countries. Leptin is predominantly produced by adipocytes and acts as a growth factor and serum leptin levels positively correlate with the amount of body fat. In this study, we investigated the effects of leptin on the growth of ovarian cancer cells and the underlying mechanism(s) of action. Our results showed that leptin stimulated the growth of the OVCAR-3 ovarian cancer cell line using MTT assay and trypan blue exclusion. Using western blot analysis, we found that leptin enhanced the expression of cyclin D1 and Mcl-1, which are important regulators of cell proliferation and the inhibition of apoptosis. To investigate the signaling pathways that mediate the effects of leptin, cells were treated with leptin plus specific inhibitors of JAK2, PI3K/Akt and MEK/ERK1/2 and analysis of the phosphorylation state of proteins was carried out by western blot assays. We showed that the activation of the MEK/ERK1/2 and PI3K/Akt signaling pathways were involved in the growth-stimulating effect of leptin on ovarian cancer cell growth and the specific inhibitors of PI3K/Akt and MEK/ERK1/2 revealed that these two pathways interacted with each other. Our data demonstrate that leptin upregulates the expression of cyclin D1 and Mcl-1 to stimulate cell growth by activating the PI3K/Akt and MEK/ERK1/2 pathways in ovarian cancer.

Obesity and prostate cancer: weighing the evidence

CONTEXT

Obesity and prostate cancer (PCa) affect substantial proportions of Western society. Mounting evidence, both epidemiologic and mechanistic, for an association between the two is of public health interest. An improved understanding of the role of this modifiable risk factor in PCa etiology is imperative to optimize screening, treatment, and prevention.

OBJECTIVE

To consolidate and evaluate the evidence for an epidemiologic link between obesity and PCa, in addition to examining the proposed underlying molecular mechanisms.

EVIDENCE ACQUISITION

A PubMed search for relevant articles published between 1991 and July 2012 was performed by combining the following terms: obesity, BMI, body mass index and prostate cancer risk, prostate cancer incidence, prostate cancer mortality, radical prostatectomy, androgen-deprivation therapy, external-beam radiation, brachytherapy, prostate cancer and quality of life, prostate cancer and active surveillance, in addition to obesity, BMI, body mass index and prostate cancer and insulin, insulin-like growth factor, androgen, estradiol, leptin, adiponectin, and IL-6. Articles were selected based on content, date of publication, and relevancy, and their references were also searched for relevant articles.

EVIDENCE SYNTHESIS

Increasing evidence suggests obesity is associated with elevated incidence of aggressive PCa, increased risk of biochemical failure following radical prostatectomy and external-beam radiotherapy, higher frequency of complications following androgen-deprivation therapy, and increased PCa-specific mortality, although perhaps a lower overall PCa incidence. These results may in part relate to difficulties in detecting and treating obese men. However, multiple molecular mechanisms could explain these associations as well. Weight loss slows PCa in animal models but has yet to be fully tested in human trials.

CONCLUSIONS

Obesity appears to be linked with aggressive PCa. We suggest clinical tips to better diagnose and treat obese men with PCa. Whether reversing obesity slows PCa growth is currently unknown, although it is an active area of research.