Ob-R Expression Research Articles

The Long Non-Coding RNA Obesity-Related (Obr) Contributes To Lipid Metabolism Through Epigenetic Regulation.

Obesity is a multifactorial disease that is part of today's epidemic and also increases the risk of other metabolic diseases. Long noncoding RNAs (lncRNAs) provide one tier of regulatory mechanisms to maintain metabolic homeostasis. Although lncRNAs are a significant constituent of the mammalian genome, studies aimed at their metabolic significance, including obesity, are only beginning to be addressed. Here, a developmentally regulated lncRNA, termed as obesity related (Obr), whose expression in metabolically relevant tissues such as skeletal muscle, liver, and pancreas is altered in diet-induced obesity, is identified. The Clone 9 cell line and high-fat diet-induced obese Wistar rats are used as a model system to verify the function of Obr. By using stable expression and antisense oligonucleotide-mediated downregulation of the expression of Obr followed by different molecular biology experiments, its role in lipid metabolism is verified. It is shown that Obr associates with the cAMP response element-binding protein (Creb) and activates different transcription factors involved in lipid metabolism. Its association with the Creb histone acetyltransferase complex, which includes the cAMP response element-binding protein (CBP) and p300, positively regulates the transcription of genes involved in lipid metabolism. In addition, Obr is regulated by Pparγ in response to lipid accumulation.

Abstract P5-02-38: Leptin receptor (Ob-R)/leptin axis significantly modulates tumour-infiltrating lymphocytes (TILs) and PD-1 expression in early HER2+ breast cancer (BC) emerging as a new surrogate marker for immunotherapy

Abstract Leptin receptor (Ob-R)/leptin axis significantly modulates tumour-infiltrating lymphocytes (TILs) and PD-1 expression in early HER2+ breast cancer (BC) emerging as a new surrogate marker for immunotherapy. Background: There is strong pre-clinical evidence that obesity produces T-cell dysfunction and high PD-1 expression resulting in a paradoxical benefit from immunotherapy. This effect is driven, at least in part, by leptin that exerts its action through binding Ob-R, which is known to be highly expressed in HER2+ BC. TILs correlate with pathological response and long-term outcomes in BC; however the precise mechanism by which these T-cells are activated in and around tumour remains partially unknown. The primary aim of this study was to investigate the role of Ob-R/leptin axis in modulating TILs and PD-1 expression and its effect in pathological response in early HER2+ BC patients who have received neoadjuvant systemic treatment (NST). Methods: Women with HER2+ BC receiving anti-HER2-based NST followed by surgical resection were evaluated. Patient’s height and weight were measured before NST to calculate the body mass index (BMI). Based on the IHC results in diagnostic biopsy, tumors were categorized as HER2+/HR+ and HER2+/HR-. Ob-R expression was routinely measured in the diagnostic biopsy using the BOND RX Research Platform (Leica Biosystems). The Ob-R was classified as over-expressed if there were more than 50% positive cells with weak or strong staining. TILs and PD-1 expression were scored centrally in pre-treatment biopsy. TILs were considered as binary, < 30.0% versus ≥30.0% and PD-1 positive (>1%). Associations with pathological complete response (pCR; ypT0/isN0) were assessed using chi-squared or Wilcoxon test. Results: Of the 74 HER2+ BC patients included in the study, 47 (63.5%) had over-expression of Ob-R, 26 (35.1%) were overweight/obese (BMI ≥25kg/m2), and 42 (56.8%) had pCR status. Ob-R expression was similar regardless of menopausal status, age or HR expression. Patients with Ob-R overexpressed were 21 (80.8%) of 26 with BMI ≥25kg/m2 versus 26 (54.2%) of 48 with BMI < 25Kg/m2 (p=0.023). Tumors with Ob-R overexpressed had significantly higher mean levels of TILs than those with non-overexpressed Ob-R (21.4% [IQR, 7.5-30] vs 12.4% [IQR, 5-10]; p=0.009). Despite higher rates of TILs, the rate of pCR in Ob-R overexpressed tumours (57.4% [27 of 47 patients]) was not higher than in non-overexpressed tumours (55.6% [15 of 27 patients]; p=0.874). This could be due to the fact that Ob-R-overexpressed tumours had a significant higher median PD-1 expression than Ob-R-negative tumours (2% [IQR, 0.5-7.5] vs 0% [IQR, 0-1]; p< 0.001). Finally, no differences were found in terms of Ob-R expression and pathological response by hormone receptor expression. Conclusions: This multidisciplinary clinical study decodes for the first time how obesity, through the OB-R/leptin axis, might activate TILs but apparently dysfunctional as it is not translated into higher pCR; probably due to the presence of exhausted features such as high PD-1 expression. The role of Ob-R together with PD-1 as a potential biomarker for immunotherapy should be further explored. Citation Format: Laura García-Estévez, Adela Fernández, José Palacios, Miguel Sampayo, Isabel Calvo, Eva Díaz, Marta González, Belén Pérez-Míes, Silvia González, José Manuel Pérez-García, Javier Cortés, Gema Moreno-Bueno. Leptin receptor (Ob-R)/leptin axis significantly modulates tumour-infiltrating lymphocytes (TILs) and PD-1 expression in early HER2+ breast cancer (BC) emerging as a new surrogate marker for immunotherapy. [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-02-38.

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

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. 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. 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). 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.

Leptin-producing monocytes in the airway submucosa may contribute to asthma pathogenesis

BackgroundObesity leads to an increase in the incidence and severity of asthma. Adipokines, such as leptin, secreted by adipocytes induce systemic inflammation, causing airway inflammation. We previously reported that leptin activates both inflammatory and structural cells, including lung fibroblasts. However, little is known about the differential leptin expression and responsiveness to leptin in asthmatic individuals and healthy controls (HC). In this study, we investigated the expression and origin of leptin in asthmatic airways. We also compared the effect of leptin on asthmatic and HC fibroblasts. MethodsLung specimens from asthmatic and non-asthmatic patients were analyzed by immunohistochemical staining using anti-leptin and anti-CD163 antibodies. Leptin mRNA and protein levels in human monocytes were detected by real-time PCR and western blotting and ELISA, respectively. We used flow cytometry to analyze asthmatic and HC lung fibroblasts for leptin receptor (Ob-R) expression. Further, we determined cytokine levels using cytometric bead array and ELISA and intracellular phosphorylation of specific signaling molecules using western blotting. ResultsAsthma specimens displayed accumulation of leptin-positive inflammatory cells, which were also positive for CD163, a high-affinity scavenger receptor expressed by monocytes and macrophages. Leptin expression was observed at both transcript and protein levels in human blood-derived monocytes. No significant differences were observed between asthmatic and HC lung fibroblasts in Ob-R expression, cytokine production, and intracellular phosphorylation of p38 mitogen-activated protein kinase. ConclusionsOur findings reveal similar responsiveness of control and asthmatic fibroblasts to leptin. However, the accumulation of inflammatory leptin-producing monocytes in the airway may contribute to the pathogenesis of asthma.

Presence of leptin and its receptor in the ram reproductive system and in vitro effect of leptin on sperm quality.

Leptin is a 16 kDa hormone encoded by obese (OB) gene in adipocytes. This molecule not only regulates energy metabolism but also plays a role in the reproduction of mammals. Leptin and its receptor (OBR) have been found in male reproductive systems of human, bovine, equine and pig. The effects of leptin on sperm quality vary widely from different research findings. However, the presence of leptin and its receptor in the ram reproductive system and the in vitro effect of leptin on sperm quality have not reported yet. In the present study, we found that the OB was highly expressed in primary and secondary spermatocytes of the testes, OBR was highly expressed in secondary spermatocytes of the testes. The expressions of OB were in stereocilia of epididymis and in columnar cells of epididymal caput and cauda, the expressions of OBR were in columnar cells of epididymis and in stereocilia of epididymal corpus and cauda. The presence of both OB and OBR in testes, epididymis and sperm were confirmed through RT-PCR, immunolocalization and Western blot analyses. The RT-qPCR results indicated OB and OBR had higher expression levels in epididymal sperm than that of the ejaculated sperm in rams. When sperm were treated with 5 ng/mL leptin, the progressive motility (P < 0.01), straight-line velocity (VSL) (P < 0.05), average path velocity (VAP) (P < 0.05), membrane mitochondrial potential (MMP) (P < 0.01) and viability (P < 0.05) significantly increased, while DNA fragmentation index (DFI) and reactive oxygen species (ROS) significantly decreased compared to the control (P < 0.01), and the other semen parameters such as acrosome integrity and acrosome reaction rate had no significant changes between groups (P > 0.05). In conclusion, this is probably the first report describing localization of leptin and its receptors in the reproductive system of rams and their effects on sperm quality parameters. Our findings suggest that 5 ng/mL leptin treatment enhanced sperm motility, viability and MMP, and decrease DFI and ROS without obvious influence on the acrosome reaction in ram sperm. The potential mechanisms may be related to leptin’s ability to reduce the oxidative stress and apoptosis of sperms and improve their mitochondrial function and energy supply, therefore, to maintain the physiological homeostasis of the sperm.

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

To investigate the molecular effects of leptin on uterine leiomyoma cells. Experimental study using invitro culture of immortalized human leiomyoma (HuLM) cells. Academic university center. Women with uterine fibroids who underwent a hysterectomy or myomectomy. 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. 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. 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. 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 Ciji-Hua'ai-Baosheng II Formula Attenuates Chemotherapy-Induced Anorexia in Mice With H22 Hepatocellular Carcinoma.

Background: Ciji-Hua’ai-Baosheng II Formula (CHB-II-F) is a traditional Chinese medicine formula, which specifically targets different aspects of chemotherapy-induced adverse effects in patients with cancer. In our clinical application, CHB-II-F significantly alleviated chemotherapy-induced anorexia (loss of appetite) and improved the quality of life for patients with tumor during and after chemotherapy. However, the mechanism of CHB-II-F in alleviation of chemotherapy-induced anorexia remains to be further investigated.Aim of Study: To explore the therapeutic effect and mechanism of CHB-II-F on chemotherapy-induced anorexia in the mice model of H22 hepatoma.Materials and Methods: A total of 72 Kunming mice of SPF grade were inoculated subcutaneously with H22 hepatoma cells into the right anterior armpit of the mice. After 1 week of seeding, mice were injected intraperitoneally with a high dose of 5-fluorouracil (200 mg/kg 5-FU) to establish the model of chemotherapy. The mice were randomly divided into six groups: untreated group, 5-FU group, 5-FU plus Yangzheng Xiaoji capsule (YZXJC) group, and three groups of 5-FU plus different concentrations of CHB-II-F. All the mice in each group were treated for 14 days. The body weight, food intake, tumor volume, and tumor weight of mice were measured, and pathological examinations of tumor tissue, stomach, and duodenum were carried out. Expressions of serum Leptin, Neuropeptide Y (NPY), epidermal cell growth factor (EGF), Motilin (MTL), Orexin A (OXA), Gastrin (GAS), Ghrelin, Prostaglandin E2 (PGE2), and jejunum superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were examined. The protein and mRNA levels of proopiomelanocortin (POMC), Orexin receptor 1 (OX1R), neuropeptide Y (NPY), cocaine and amphetamine regulated transcript peptide (CART), Agouti gene-related protein (AgRP), Leptin receptor (Ob-R), and Ghrelin receptor (GHSR) were examined in hypothalamus, and the protein levels of substance P (SP) and 5-hydroxytryptamine (5-HT) in duodenum were measured.Results: The combination of CHB-II-F and 5-FU could enhance the inhibitory effect of 5-FU on tumor. The tumor inhibition rates of 5-FU group, YZXJC group, CHB-II-F(H) group, CHB-II-F(M) group, and CHB-II-F(L) group were 58.88, 28.08, 54.96, 37.69, and 28.61%, respectively. Compared with untreated group and 5-FU group, CHB-II-F significantly increased the body weight and food intake of tumor-bearing mice; increased the content of NPY, Orexin A, Ghrelin, GAS, MTL, EGF, and PGE2 in serum and the activity of SOD in jejunum; and decreased the content of Leptin in serum and the content of MDA in jejunum. Compared with untreated group and 5-FU group, CHB-II-F also enhanced the expression of OX1R, GHSR, NPY, and AgRP protein and gene and decreased the expression of Ob-R, POMC, and CART protein and gene in hypothalamus of mice, and the gene expression was consistent with the protein expression. In addition, CHB-II-F decreased the expression of 5-HT and SP protein in duodenum.Conclusion: In the murine model of H22 hepatocellular carcinoma (HCC) receiving chemotherapy, CHB-II-F enhances the inhibitory effect of 5-FU on tumor, significantly improves the pathological injury of gastrointestinal tract caused by chemotherapy, and regulates the secretion of gastrointestinal hormones. It may alleviate chemotherapy-induced anorexia by affecting appetite regulatory factors in the feeding area of hypothalamus central nervous system and peripheral appetite regulatory factors.

Predictive Role of Leptin Receptor (Ob-R) Overexpression in Patients with Early Breast Cancer Receiving Neoadjuvant Systemic Treatment.

Simple SummaryObesity and overweight, considered the pandemic disease in the 21st century, is highly related to breast cancer. Leptin receptor (Ob-R) and its ligand leptin display an important role in driving this connection. Nowadays, translational cancer research is mainly focused on the identification of new biomarkers able to discriminate those patients deriving greater efficacy from a given therapy. In this regard, our study examines the role of Ob-R, namely, the correlation between Ob-R and pathological complete Response (pCR) in early breast cancer patients receiving neoadjuvant systemic therapy. Here, we decoded the correlation of Ob-R with certain clinical features such as breast cancer subtype, age, body mass index (BMI), menopausal status, and mammogram breast density. The study provides further support for the potential value of Ob-R for the first time as a possible role for predicting pCR. Moreover, we would like to highlight the importance of Ob-R as independent predictive factors for pCR in breast cancer patients.The primary aim of this retrospective study was to investigate the correlation between the immunohistochemical expression of Ob-R (leptin receptor) with pCR (pathological complete response) in early breast cancer patients receiving neoadjuvant systemic treatment (NST). A total of 100 women with breast cancer receiving NST (2017–2020) followed by surgical resection were retrospectively obtained. Demographic parameters and clinicopathological factors (e.g., treatment modalities, immunohistochemistry (IHC), and cancer subtype) were obtained from the patient’s clinical records. In the analyzed breast cancer cohort, high expression of Ob-R was found in 52% of tumors and there was a significantly higher incidence in the HER2+ and TNBC subgroups. Overall, a significantly greater percentage of patients with Ob-R positive tumors achieved pCR compared with Ob-R negative patients (57.7% vs. 27.1%; p = 0.002). This result was observed in most breast cancer subtypes. In patients with HER2+ breast cancer, there was no difference in Ob-R expression in relation to the HR status. Ob-R cell positivity was significantly higher in younger breast cancer patients (p = 0.008), those who were premenopausal (p = 0.011), and in those with a BMI > 25 kg/m2 (p = 0.019). A significantly greater percentage of early breast cancer patients with Ob-R positive tumors achieved pCR compared with Ob-R negative patients. Furthermore, breast cancer patients with positive Ob-R expression were significantly younger than those with negative Ob-R expression. This association was not explained by differences in BMI between young and old patients.

Immunolocalization of leptin and leptin receptor in colorectal mucosa of ulcerative colitis, Crohn\u2019s disease and control subjects with no inflammatory bowel disease

The expression of leptin and leptin receptor (Ob-R) has been partially elucidated in colon of patients with inflammatory bowel diseases (IBDs), even though leptin is involved in angiogenesis and inflammation. We previously reported overexpression of GLUT5 fructose transporter, in aberrant clusters of lymphatic vessels in lamina propria of IBD and controls. Here, we examine leptin and Ob-R expression in the same biopsies. Specimens were obtained from patients with ulcerative colitis (UC), Crohn’s disease (CD) and controls who underwent screening for colorectal cancer, follow-up after polypectomy or with a history of lower gastrointestinal symptoms. Immunohistochemistry revealed leptin in apical and basolateral membranes of short epithelial portions, Ob-R on the apical pole of epithelial cells. Leptin and Ob-R were also identified in structures and cells scattered in the lamina propria. In UC, a significant correlation between leptin and Ob-R in the lamina propria was found in all inflamed samples, beyond non-inflamed samples of the proximal tract, while in CD, it was found in inflamed distal samples. Most of the leptin and Ob-R positive areas in the lamina propria were also GLUT5 immunoreactive in inflamed and non-inflamed mucosa. A significant correlation of leptin or Ob-R expression with GLUT5 was observed in the inflamed distal samples from UC. Our findings suggest that there are different sites of leptin and Ob-R expression in large intestine and those in lamina propria do not reflect the status of mucosal inflammation. The co-localization of leptin and/or Ob-R with GLUT5 may indicate concomitance effects in colorectal lamina propria areas.

Combination of Silibinin and Curcumin Reduced Leptin Receptor Expression in MCF-7 Human Breast Cancer Cell Line.

Background: Leptin and leptin receptor (Ob-R) are associated with worse prognosis, distant metastasis, and poor survival of breast cancer. We investigated the cytotoxic effect of silibinin and curcumin, individually and combined, on Ob-R expression in MCF-7 cells.Methods: This study was performed from October 2017 to April 2018 at the Department of Clinical Biochemistry, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. The cytotoxic effect of silibinin and curcumin, individually and combined, and their corresponding half-maximal inhibitory concentration (IC50) values were determined using the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay. The cells were treated with different concentrations of silibinin (50-400 μM), curcumin (10-35 μM), and their combinations for 24 and 48 hours. The expression of Ob-R was measured using the Western blot analysis by treating the cells with different concentrations of curcumin (10-25 μM), silibinin (50-250 μM), and their respective combinations. The difference in mean cell viability between the groups was calculated using one-way ANOVA followed by Tukey’s post hoc test.Results: Silibinin and curcumin exerted time- and dose-dependent cytotoxic effect on MCF-7 cells. After treatment with silibinin, the IC50 values were about 250 and 50 μM at 24 and 48 hours, respectively. In terms of treatment with curcumin, the IC50 values were about 25 and 15 μM at 24 and 48 hours, respectively. Following treatment with silibinin, the Western blot analysis showed that Ob-R expression significantly decreased at 150 μM (P=0.031) and 200 μM (P=0.023) concentrations. Curcumin did not significantly decrease the Ob-R expression, however, the expression significantly decreased (P=0.004) when it was combined with silibinin.Conclusion: The combination of silibinin and curcumin significantly reduced Ob-R expression in MCF-7 cells compared with their individual effects.

Beige adipocytes contribute to breast cancer progression.

Adipocytes are the main stromal cells in the mammary microenvironment, and crosstalk between adipocytes and breast cancer cells may play a critical and important role in cancer maintenance and progression. Tumor‑induced differentiation to beige/brown adipose tissue is an important contribution to the hypermetabolic state of breast cancer. However, the effect of epithelial cell‑beige adipocyte communication on tumor progression remains unclear. To contribute to the understanding of this phenomenon, we characterized components present in conditioned media(CM) from beige adipocytes (BAs) or white adipocytes(WAs), and evaluated the effects of BA‑ and WA‑CM on both adhesion and migration of tumor (LM3, 4T1 and MC4‑L1) and non‑tumor (NMuMG) mouse mammary epithelial cell lines. Additionally, we analyzed the expression of ObR, CD44, vimentin, MMP‑9, MCT1 and LDH in tumor and non‑tumor mouse mammary epithelial cell lines incubated with BA‑CM, WA‑CM or Ctrol‑CM (control conditioned media). 3T3‑L1 preadipocytes differentiated into beige adipocytes upon PPARγ activation (rosiglitazone) displaying characteristics that morphologically resembled brown/beige adipocytes. Levels of UCP1, CIDEA, GLUT4, leptin, MCT4 and FABP4 were increased, while adiponectin, caveolin 1 and perilipin 1 levels were decreased in BAs with respect to WAs. Tumor cell lines revealed lower cell adhesion and increased cell migration after incubation with BA‑ and WA‑CM vs. Ctrol‑CM. ObR and MMP‑9 in MC4‑L1 cells were significantly increased after incubation with BA‑CM vs. WA‑ and Ctrol‑CM. In addition, MC4‑L1 and LM3 cells significantly increased their migration in the presence of BAs, suggesting that new signals originating from the crosstalk between BAs and tumor cells, could be responsible for this change. Our results indicate that beige adipocytes are able to regulate the behavior of both tumor and non‑tumor mouse mammary epithelial cells, favoring tumor progression.

Leptin reduces in vitro cementoblast mineralization and survival as well as induces PGE2 release by ERK1/2 commitment

ObjectivesJuvenile obesity is a complex clinical condition that is present more and more frequently in the daily orthodontic practice. Over-weighted patients have an impaired bone metabolism, due in part to their increased levels of circulating adipokines. Particularly, leptin has been reported to play a key role in bone physiology. Leptin is ubiquitously present in the body, including blood, saliva, and crevicular fluid. If, and to what extent, it could influence the reaction of cementoblasts during orthodontic-induced forces is yet unknown.Material and methodsOCCM-30 cementoblasts were cultivated under compressive forces using different concentrations of leptin. The expression of ObR, Runx-2, Osteocalcin, Rank-L, Sost, Caspase 3, 8, and 9 were analyzed by RT-PCR. Western blots were employed for protein analysis. The ERK1/2 antagonist FR180204 (Calbiochem) was used and cPLA2 activation, PGE2, and cytochrome C release were further evaluated.ResultsIn vitro, when compressive forces are applied, leptin promotes ERK1/2 phosphorylation, as well as upregulates PGE2 and caspase 3 and caspase 9 on OCCM cells. Blockade of ERK1/2 impairs leptin-induced PGE2 secretion and reduced caspase 3 and caspase 9 expression.ConclusionsLeptin influences the physiological effect of compressive forces on cementoblasts, exerting in vitro a pro-inflammatory and pro-apoptotic effect.Clinical relevanceOur findings indicate that leptin exacerbates the physiological effect of compressive forces on cementoblasts promoting the release of PGE2 and increases the rate of cell apoptosis, and thus, increased levels of leptin may influence the inflammatory response during orthodontically induced tooth movement.

Combined effects of obesity and di-(2-ethylhexyl) phthalate on testosterone levels and kisspeptin/GPR54 expression in hypothalamus and testes of male mice.

Background:This study evaluated whether obese male mice exposed to di-(2-ethylhexyl) phthalate (DEHP) showed synergistic effects on testosterone levels and the potential underlying mechanism.Methods:Forty-eight male mice were assigned to six groups for 12-week treatments as follows: normal, DEHP100, diet-induced obesity (DIO), DIO + DEHP30, DIO + DEHP100, and DIO + DEHP300. Serum hormone levels, including testosterone (T), luteinizing hormone (LH), and leptin, were detected by ELISA. The levels of Ob-R, kisspeptin, and GPR54 protein expression in hypothalamus and testicular tissues were measured by western blot.Results:There were significantly lower levels of serum T and LH, higher levels of serum leptin and Ob-R, and kisspeptin and GPR54 protein expression were reduced in hypothalamus and testicular tissues in the DIO and DEHP groups compared with controls. Moreover, serum T and leptin levels were more severe in the combined DIO and DEHP exposure group than in the single exposure groups. Serum LH levels and GPR54 expression in the testis were significantly decreased in DIO + DEHP300 mice compared with DIO mice (p < 0.05).Conclusion:Obesity- and DEHP-only exposure had adverse effects on testosterone levels in mice, which may be due to high leptin levels and decreased Ob-R, kisspeptin, and GPR54 expression. Obesity combined with DEHP exposure had an additive adverse effect on testosterone levels in mice. One of the potential mechanisms is higher leptin levels and decreased GPR54 expression in the testes.

Leptin Promotes Prostate Cancer Proliferation and Migration by Stimulating STAT3 Pathway

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

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

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

Effect and mechanism of ikkβ on proliferation, apoptosis, and metastasis of breast cancer cells with different expression levels of leptin and its receptors.

e15592 Background: To investigate the effect and mechanism of IKKβ on proliferation, apoptosis, invasion and metastasis of breast cancer cells with different expression levels of leptin and ObR. Methods: IKKβ in breast cancer cells was knocked down via virus transfection technology. MTT, flow cytometry, cell scratch test and clone formation test were used to observe the effect of IKKβ on proliferation, apoptosis and metastasis of breast cancer cells with different expression levels of leptin and ObR. RT-PCR was used to detect the downstream genes expressions in IKKβ signaling pathway. Results: The expression levels of leptin and ObR in MDA-MB-231 cells were higher than those in MCF-7 cells. Lentivirus can successfully infect breast cancer cells in vitro and knock down the expression of IKKβ. Knocking down IKKβ reduced the viability of MDA-MB-231 cells, but had little effect on MCF-7, and had an effect on the cell cycle of both cells. After knocking down IKKβ, the apoptotic rate of MDA-MB-231 cells increased. There was no significant difference in the apoptotic rate of MCF-7 cells. The number of clones of MCF-7 and MDA-MB-231 cells decreased, and the difference was significant. The effect on MDA-MB-231 cells was more significant. The scratch mobility of MDA-MB-231 cells decreased significantly, with significant difference.After knocking down IKKβ, the expressions of leptin and ObR, IKBKG, P65 and HIF in MCF-7 cells were significantly decreased, and there was statistical significance. However, the above indicators were significantly increased in MDA-MB-231 cells. The expression level of IKBKG was increased significantly, whereas that of HIF did not differ significantly, as compared with that of control group. Conclusions: The proliferation, metastasis and apoptosis of MDA-MB-231 cells were inhibited after blocking the IKKβ pathway, while the proliferation of MCF-7 cells was inhibited, and the apoptosis did not change significantly. The difference between the two cells may be related to the different expression levels of leptin and ObR.After blocking the IKKβ signaling pathway, the expressions of genes related to the IKKβ signaling pathway in MDA-MB-231 cells were increased, whereas those in MCF-7 cells were decreased, which might be related to the different expression levels of leptin and ObR.After knocking down IKKβ, the expressions of HIF gene in MCF-7 cells were decreased, whereas those in MDA-MB-231 cell lines were not affected. It needs to be verified whether this difference is related to leptin and ObR.

Effect of metformin on testicular expression and localization of leptin receptor and levels of leptin in the diabetic mice

Diabetes mellitus impairs testicular activity and leads to infertility. Leptin is one of the endogenous regulators of the male reproductive functions, but the role of leptin and its receptor (LEPR/Ob-R) in the control of testosterone production and testicular proliferation has not been investigated so far, especially in the Type 1 diabetes mellitus (DM1). Metformin is an anti-hyperglycemic drug which is beneficial for treating the both DM2 and DM1. The aim of this work was to study the possible role of leptin and Ob-R in the regulation of steroidogenesis and proliferation in the testes of mice with streptozotocin-induced DM1 (75 mg/kg/day, 4 days) and to estimate the restoring effect of metformin treatment (500 mg/kg, 2 weeks) on the diabetic testes. In the diabetic testes, the plasma and intratesticular leptin levels and plasma testosterone levels were reduced and completely restored by metformin treatment. Metformin also restored the expression of the steroidogenic transport protein steroidogenic acute regulatory protein reduced in DM1. In the diabetic testes, the expression of Ob-R was downregulated and the immunolocalization of Ob-R showed weak staining in the Leydig cells, the primary spermatocytes and the round spermatids. The germ cell proliferation was also reduced in DM1, as noticed with proliferating cell nuclear antigen (PCNA) expression. Metformin increased the Ob-R expression and immunostaining in the different cell types and improved the PCNA expression. Thus, DM1 impairs the testicular steroidogenesis and proliferation by inhibiting the leptin signaling, causing a decrease in leptin levels and Ob-R expression in the testes of diabetic mice, while metformin improves the leptin signaling and restores testosterone production and testicular proliferation.

Human renal adipose tissue from normal and tumor kidney: its influence on renal cell carcinoma.

Tumor cells can interact with neighboring adipose tissue. We evaluated components present in human adipose explants from normal (hRAN) and kidney cancer (hRAT) tissue, and we evaluated the effects of conditioned media (CMs) from hRAN and hRAT on proliferation, adhesion and migration of tumor and non-tumor human renal epithelial cell lines. In addition, we evaluated the expression of AdipoR1, ObR, CD44, vimentin, pERK and pPI3K on cell lines incubated with CMs. hRAN were obtained from healthy operated donors, and hRAT from patients who underwent a nephrectomy. hRAT showed increased levels of versican, leptin and ObR; and decreased levels of perilipin, adiponectin and AdipoR1, compared to hRAN. Cell lines showed a significant decrease in cell adhesion and increase in cell migration after incubation with hRAT-CMs vs. hRAN- or control-CMs. Surprisingly, HK-2, 786-O and ACHN cells showed a significant decrease in cell migration after incubation with hRAN-CMs vs. control-CMs. No difference in proliferation of cell lines was found after 24 or 48 h of treatment with CMs. AdipoR1 in ACHN and Caki-1 cells decreased significantly after incubation with hRAT-CMs vs. hRAN-CMs and control-CMs. ObR and CD44 increased in tumor line cells, and vimentin increased in non-tumor cells, after incubation with hRAT-CMs vs. hRAN-CMs and control-CMs. We observed an increase in the expression of pERK and pPI3K in HK-2, 786-O and ACHN, incubated with hRAT-CMs. In conclusion, results showed that adipose microenvironment can regulate the behavior of tumor and non tumor human renal epithelial cells.

The role of miR200c in leptin-mediated triple-negative breast cancer progression to an epithelial-to-mesenchymal transition.

e12548 Background: Almost 40% of women with breast cancer are obese at diagnosis. Obesity is associated with a worse prognosis in triple negative breast cancer (TNBC). Preclinical studies have shown that leptin is an important factor associated with TNBC by promoting cancer stem cell (CSC) enrichment and/or epithelial-to-mesenchymal transition (EMT). Transcription factors SNAIL, TWIST and ZEB are critical components in enhancing EMT in cancer cells. The specific mechanism(s) by leptin regulates SNAIL, TWIST and ZEB expression remain unclear, limiting the development of effective interventions to improve outcomes in obese TNBC patients. Recent studies have demonstrated that miR200c, downstream of leptin receptor signaling, regulates the expression of SNAIL1, TWIST and ZEB. We will test the hypothesis that leptin contributes to obesity-induced EMT/CSC in TNBC through modulation of miR200c. Methods: Ob-R (leptin receptor) expression was suppressed in TNBC MDA-MB-231 and E-Wnt cells using shRNA (Ob-R null). Ob-R and Ob-R null cells were exposed to sera pooled from lean or obese women, as well as lean sera supplemented with leptin, after which expression of SNAIL, TWIST, ZEB and miR200c was measured by qPCR, while activation of the JAK-STAT pathway was assessed by Western blotting. Results: TNBC cells exposed to obese and high leptin conditions demonstrated increased expression of EMT markers compared to levels expressed under lean conditions. The Ob-R WT and null cells were used to determine the specific role of leptin signaling in regulating expression of SNAIL, TWIST and ZEB through miR200c. Conclusions: Both obese and high leptin conditions result in increased expression of EMT regulators, suggesting that effective targeting of this pathway may provide clinical benefit in the obese breast cancer patient. Elucidating the specific mediators of this pathway will guide development of novel and more potent medical therapies.

Naringin attenuates high glucose-induced injuries and inflammation by modulating the leptin-JAK2/STAT3 pathway in H9c2 cardiac cells.

IntroductionOur previous study showed that naringin (NRG) protects cardiomyocytes against high glucose (HG)-induced injuries by inhibiting p38 mitogen-activated protein kinase (MAPK). Leptin induces hypertrophy in rat cardiomyocytes via p38/MAPK activation. The present study aimed to test the hypothesis that leptin-Janus kinase 2 (JAK2)/signal transducers and activators of transcription 3 (STAT3), which are responsible for leptin’s functions, are involved in HG-induced injuries and cardioprotective effects of NRG in cardiomyocytes.Material and methodsH9c2 cells were exposed to HG for 24 h to establish a cardiomyocyte injury model. Cells were pretreated with NRG and other drugs before exposure to HG. Protein expression was measured by western blot analysis. Cell viability was detected by Cell Counting Kit-8 assay. Apoptotic cells were assessed by Hoechst 33258 staining assay. Intracellular reactive oxygen species levels were determined by dichlorofluorescein diacetate staining. Mitochondrial membrane potential was evaluated using JC-1. An enzyme-linked immunosorbent assay was performed to determine the inflammatory cytokines.ResultsNRG significantly attenuated HG-induced increases in leptin and Ob-R expression. Pretreatment with either a leptin antagonist (LA) or NRG markedly ameliorated HG-induced elevation of phosphorylated (p)-JAK2 and p-STAT3, respectively. Pretreatment with NRG, LA, Ob-R antagonist, or AG490 clearly alleviated HG-induced injuries and inflammation.ConclusionsThis study provides new evidence of the NRG protective effects of H9c2 cells against HG-induced injuries possibly via modulation of the leptin-JAK2/STAT3 pathway.