Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Gliclazide, a second-generation sulfonylurea, has anti-oxidant properties as well as hypoglycemic activities. In the present study, we investigated whether gliclazide affected proliferation and/or differentiation of HW white and HB2 brown adipocyte cell lines. Gliclazide inhibited proliferation of HW and HB2 cells in the medium containing fetal calf serum or epidermal growth factor (EGF). Gliclazide inhibited phosphorylation of EGF receptor and of extracellular signal-regulated kinase (ERK) 1/2 stimulated by EGF. Gliclazide increased lipid accumulation and peroxisome proliferator-activated receptor gamma (PPARgamma) expression in the early stage of differentiation of adipocytes. A K(ATP) channel activator, diazoxide, did not inhibit the increase of lipid accumulation by gliclazide. Furthermore, gliclazide inhibited the DNA-binding activity of PPARgamma in mature adipocytes. On the other hand, glibenclamide, other sulfonylurea, did not show these effects. These results indicate gliclazide inhibits proliferation and stimulates differentiation of adipocytes via down-regulation of the EGFR signalling. Gliclazide may have preventive and therapeutic effects on obesity, as well as on type 2 diabetes.
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PMID:Gliclazide inhibits proliferation but stimulates differentiation of white and brown adipocytes. 1796 69

Pathologic conditions associated with hyperinsulinemia, such as obesity, metabolic syndrome, and diabetes, seem to increase the risk of breast cancer. Here, we studied molecular mechanisms by which insulin activates the expression of leptin, an obesity hormone that has been shown to promote breast cancer progression in an autocrine or paracrine way. Using MDA-MB-231 breast cancer cells, we found that (a) insulin stimulated leptin mRNA and protein expression, which was associated with increased activation of the leptin gene promoter; (b) insulin increased nuclear accumulation of transcription factors hypoxia inducible factor (HIF)-1alpha and Sp1 and their loading on the leptin promoter; (c) small interfering RNA (siRNA)-mediated knockdown of either HIF-1alpha or Sp1 significantly down-regulated insulin-induced leptin mRNA and protein expression; further inhibition of leptin expression was observed under the combined HIF-1alpha and Sp1 siRNA treatment; (d) inhibition of extracellular signal-regulated kinase (ERK)1/2 and phosphatidylinositol-3-OH kinase (PI-3K) pathways significantly, albeit partially, decreased insulin-dependent leptin mRNA and protein expression, which coincided with reduced association of HIF-1alpha and/or Sp1 with specific leptin promoter regions; and (e) inhibition of ERK1/2 reduced recruitment of both HIF-1alpha and Sp1 to the leptin promoter, whereas down-regulation of PI-3K influenced only HIF-1alpha binding. In summary, our data suggest that hyperinsulinemia could induce breast cancer progression through leptin-dependent mechanisms. In MDA-MB-231 cells, this process requires Sp1- and HIF-1alpha-mediated leptin gene transcription and is partially regulated by the PI-3K and ERK1/2 pathways.
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PMID:Insulin-dependent leptin expression in breast cancer cells. 1855 40

It is established that increases in neuropeptide Y (NPY) expression are associated with hyperphagia and obesity. These effects can be reversed by estrogen, a recognized anorexigen. We found that 17beta-estradiol (E(2)) regulates biphasic NPY gene expression in a clonal, immortalized hypothalamic cell line, N-38, through estrogen receptor (ER) action at the level of the NPY promoter. However, rapid, nongenomic actions of estrogen, linked to the phosphatidylinositol 3-kinase (PI3-K)/Akt and ERK1/2 mitogen-activated protein kinase (MAPK) pathways, may also play a role. We therefore examined the changes in the phosphorylation status of Akt, ERK1/2, and cAMP response element-binding protein (CREB) after treatment with 10 nm E(2) in the N-38 neurons and found activation of these signaling proteins within 5-30 min. We also demonstrated possible cross talk between the estrogen-activated PI3-K/Akt and MAPK/extracellular signal-regulated kinase pathways using pharmacological inhibitors. We find that only ERalpha is involved in the early signaling events using the ERalpha agonist 4,4',4''-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol and the ERbeta agonist 2,3-bis(4-hydroxyphenyl)-propionitrile. Furthermore, we can detect colocalization of ERalpha and caveolin-1, a membrane-associated signaling protein. Remarkably, we find that the membrane-mediated events are critical for the long-term estrogen-mediated repression of NPY gene expression that can be mapped to within -97 bp of the NPY promoter. To link the early signaling events to downstream effectors, we detected induction of c-fos and inactivation of MSK-1 by estrogen and binding of CREB to this minimal promoter region. These observations suggest that rapid estrogen-mediated signaling is mediated by ERalpha, and the signal transduction events potentiate the genomic actions of estrogen on NPY gene expression in the N-38 NPY neurons.
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PMID:Estrogen facilitates both phosphatidylinositol 3-kinase/Akt and ERK1/2 mitogen-activated protein kinase membrane signaling required for long-term neuropeptide Y transcriptional regulation in clonal, immortalized neurons. 1856 18

Obesity is an independent risk factor for breast cancer, and obese breast cancer patients exhibit a higher risk for larger tumor burden and increased metastasis. Obesity, as associated with metabolic syndrome, results in an increase in circulating insulin-like growth factor (IGF), which acts as a mitogen. In addition, higher plasma level of adipocytokine leptin is associated with obesity. In the present study, we show that cotreatment with leptin and IGF-I significantly increases proliferation as well as invasion and migration of breast cancer cells. We found a novel bidirectional crosstalk between leptin and IGF-I signaling; IGF-I induced phosphorylation of leptin receptor (Ob-Rb) and leptin induced phosphorylation of IGF-I receptor (IGF-IR), whereas cotreatment induced synergistic phosphorylation and association of Ob-Rb and IGF-IR along with activation of downstream effectors, Akt and extracellular signal-regulated kinase. Leptin increased phosphorylation of IGF signaling molecules insulin-receptor substrate (IRS)-1 and IRS-2. Interestingly, we found that leptin and IGF-I cotreatment synergistically transactivated epidermal growth factor receptor (EGFR), depending on the proteolytic release of EGFR ligands, as the broad-spectrum matrix metalloproteinase inhibitor GM6001 could inhibit this effect. Using clinically relevant EGFR inhibitors, erlotinib and lapatinib, we found that inhibition of EGFR activation effectively inhibited leptin- and IGF-I-induced invasion and migration of breast cancer cells. Taken together, these data suggest a novel bidirectional crosstalk between leptin and IGF-I signaling that transactivates EGFR and promotes the metastatic properties as well as invasion and migration of breast cancer cells. Our findings indicate the possibility of using EGFR inhibitors erlotinib and lapatinib to counter the procancerous effects of leptin and IGF-I in breast cancers.
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PMID:Bidirectional crosstalk between leptin and insulin-like growth factor-I signaling promotes invasion and migration of breast cancer cells via transactivation of epidermal growth factor receptor. 1904 49

Hyperleptinemia is a common feature of obese women who have a higher risk of endometrial cancer than women with normal weights, and epidemiologic studies have suggested a correlation between obesity and endometrial carcinoma. Therefore, understanding of the molecular mechanism involved in leptin signaling transduction is important in endometrial cancer prevention and treatment. In this study, both isoforms of the leptin receptor (Ob-R), the long form (Ob-Rb) and short form (Ob-Ra), were detected as being expressed in six endometrial cancer cell lines with various differentiation status by western blotting, and Ob-Ra was found to be more abundant than Ob-Rb in these cells. Moreover, the expressions of both isoforms were inversely correlated with histoprognostic grading. We also showed that leptin stimulated cell proliferation and induced activations of signal transducers and activators of transcription 3 (STAT3), extracellular signal-regulated kinase (ERK1/2), AKT, and cyclooxygenase (COX)-2 in endometrial cancer cells dose-dependently by [(3)H] thymidine incorporation assay and western blotting. Leptin-stimulation resulted in increased expression of COX-2 mRNA and prostaglandin E2 (PGE2) production of endometrial cancer cells by reverse transcription-polymerase chain reaction and enzyme immunoassay, respectively, which was effectively blocked by pharmacological inhibitors of Janus tyrosine kinase 2 (JAK2), AG490; of mitogen-activated protein kinase (MAPK) kinase, U0126; of phosphatidylinositol 3-kinase (PI3K), LY294002; and of COX-2, NS398. These results suggest that leptin promotes cell proliferation of endometrial cancer cells via the aforementioned multiple signal-transduction pathways. Leptin-induced functional activation of COX-2 is JAK2/STAT3-, MAPK/ERK-, and PI3K/AKT-dependent, indicating that COX-2 may be a critical factor of endometrial carcinogenesis in obesity.
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PMID:Leptin induces functional activation of cyclooxygenase-2 through JAK2/STAT3, MAPK/ERK, and PI3K/AKT pathways in human endometrial cancer cells. 1915 13

Macrophage infiltration of white adipose tissue (WAT) is implicated in the metabolic complications of obesity. In addition, inflammatory changes through dysregulated expression of inflammation-related adipokines such as tumor necrosis factor-alpha (TNF-alpha) and monocyte chemoattractant protein-1 (MCP-1) in WAT are considered to be one of the causes of insulin resistance. Recently, enhanced oxidative stress in adipocytes has been reported to be implicated in dysregulated expression of inflammation-related adipokines. Polyphenols are well known as potent natural antioxidants in the diet. In the present study, we investigated the antioxidative effects of an oligomerized grape seed polyphenol (OGSP) on inflammatory changes in coculture of adipocytes and macrophages. Coculture of HW mouse white adipocytes and RAW264 mouse macrophages markedly increased the production of TNF-alpha, MCP-1 and plasminogen activator inhibitor-1 compared with control culture. Treatment of HW cells with OGSP significantly attenuated the dysregulated production of adipokines. Moreover, OGSP significantly suppressed coculture-induced production of reactive oxygen species (ROS). Although enhanced release of free fatty acids (FFAs) by coculture was not altered by OGSP, FFA-induced ROS production in HW cells was significantly attenuated by OGSP. Furthermore, OGSP significantly reduced increases in the transcriptional activity of nuclear factor-kappaB and activation of extracellular signal-regulated kinase by coculture. Thus, these results suggest that the antioxidative properties of OGSP attenuate inflammatory changes induced by the coculture of adipocytes and macrophages.
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PMID:Oligomerized grape seed polyphenols attenuate inflammatory changes due to antioxidative properties in coculture of adipocytes and macrophages. 1915 28

Infection with Trypanosoma cruzi, the etiologic agent of Chagas disease is accompanied by an intense inflammatory reaction. Our laboratory group has identified adipose tissue as one of the major sites of inflammation during disease progression. Because adipose tissue is composed of many cell types, we were interested in investigating whether the adipocyte per se was a source of inflammatory mediators in this infection. Cultured adipocytes were infected with the Tulahuen strain of T. cruzi for 48-96 h. Immunoblot and quantitative PCR (qPCR) analyses demonstrated an increase in the expression of proinflammatory cytokines and chemokines, including interleukin (IL)-1 beta, interferon-gamma, tumor necrosis factor-alpha, CCL2, CCL5, and CXCL10 as well as an increase in the expression of Toll-like receptors-2 and 9 and activation of the notch pathway. Interestingly, caveolin-1 expression was reduced while cyclin D1 and extracellular signal-regulated kinase (ERK) expression was increased. The expression of PI3kinase and the activation of AKT (phosphorylated AKT) were increased suggesting that infection may induce components of the insulin/IGF-1 receptor cascade. There was an infection-associated decrease in adiponectin and peroxisome proliferator-activated receptor-gamma (PPAR-gamma). These data provide a mechanism for the increase in the inflammatory phenotype that occurs in T. cruzi-infected adipocytes. Overall, these data implicate the adipocyte as an important target of T. cruzi, and one which contributes significantly to the inflammatory response observed in Chagas disease.
Obesity (Silver Spring) 2008 Sep
PMID:Trypanosoma cruzi infection of cultured adipocytes results in an inflammatory phenotype. 1918 25

Small Heterodimer Partner (SHP) inhibits activities of numerous transcription factors involved in diverse biological pathways. As an important metabolic regulator, SHP plays a key role in maintaining cholesterol and bile acid homeostasis by inhibiting cholesterol conversion to bile acids. While SHP gene induction by increased bile acids is well established, whether SHP activity is also modulated remains unknown. Here, we report surprising findings that SHP is a rapidly degraded protein via the ubiquitin-proteasomal pathway and that bile acids or bile acid-induced intestinal fibroblast growth factor 19 (FGF19) increases stability of hepatic SHP by inhibiting proteasomal degradation in an extracellular signal-regulated kinase (ERK)-dependent manner. SHP was ubiquitinated at Lys122 and Lys123, and mutation of these sites altered its stability and repression activity. Tandem mass spectrometry revealed that upon bile acid treatment, SHP was phosphorylated at Ser26, within an ERK motif in SHP, and mutation of this site dramatically abolished SHP stability. Surprisingly, SHP stability was abnormally elevated in ob/ob mice and diet-induced obese mice. These results demonstrate an important role for regulation of SHP stability in bile acid signaling in normal conditions, and that abnormal stabilization of SHP may be associated with metabolic disorders, including obesity and diabetes.
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PMID:Bile acid signaling pathways increase stability of Small Heterodimer Partner (SHP) by inhibiting ubiquitin-proteasomal degradation. 1939 91

Systemic homeostasis requires coordinated metabolic regulation among multiple tissues/organs via inter-organ communication. We have reported that neuronal signaling plays important roles in this inter-organ metabolic communication. First, we found that liver-selective extracellular signal-regulated kinase (ERK) activation induces insulin hypersecretion and pancreatic beta cell proliferation. Denervation experiments revealed that these inter- organ (liver-to-pancreas) effects are mediated by a neural relay consisting of splanchnic afferents (from the liver) and vagal efferents (to the pancreas). The central nervous system also participates in this inter-organ communication. This neural relay system originating in the liver is physiologically involved in the anti-diabetes mechanism whereby, during obesity development, insulin hypersecretion and pancreatic beta cell hyperplasia occur in response to insulin resistance. This indicates the pathophysiological importance of this system in diabetes prevention and hyperinsulinemia development. Furthermore, when applied to mouse models of insulin-deficient diabetes, both type 1 and type 2, hepatic activation of ERK signaling increased pancreatic beta cell mass and normalized blood glucose. Thus, this inter-organ system may serve as a valuable therapeutic target for diabetes by regenerating pancreatic beta cells. The concept that manipulation of an endogenous mechanism can regenerate a damaged tissue in vivo may open a new paradigm for regenerative trreatments for degenerative disorders.
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PMID:Neural relay from the liver induces proliferation of pancreatic beta cells: a path to regenerative medicine using the self-renewal capabilities. 1990 8

The influence of ethanolic extracts of Brassica campestris spp. rapa roots (EBR) on obesity was examined in imprinting control region (ICR) mice fed a high-fat diet (HFD) and in 3T3-L1 adipocytes. The ICR mice used were divided into regular diet, HFD, EBR (50 mg/kg/day EBR administered orally), and orlistat (10 mg/kg/day orlistat administered orally) groups. The molecular mechanism of the anti-obesity effect of EBR was investigated in 3T3-L1 adipocytes as well as in HFD-fed ICR mice. In the obese mouse model, both weight gain and epididymal fat accumulation were highly suppressed by the daily oral administration of 50 mg/kg EBR for 8 weeks, whereas the overall amount of food intake was not affected. EBR treatment induced the expression in white adipocytes of lipolysis-related genes, including beta(3)-adrenergic receptor (beta(3)-AR), hormone-sensitive lipase (HSL), adipose triglyceride lipase, and uncoupling protein 2. Furthermore, the activation of cyclic AMP-dependent protein kinase, HSL, and extracellular signal-regulated kinase was induced in EBR-treated 3T3-L1 cells. The lipolytic effect of EBR involved beta(3)-AR modulation, as inferred from the inhibition by the beta(3)-AR antagonist propranolol. These results suggest that EBR may have potential as a safe and effective anti-obesity agent via the inhibition of adipocyte lipid accumulation and the stimulation of beta(3)-AR-dependent lipolysis.
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PMID:Ethanolic extracts of Brassica campestris spp. rapa roots prevent high-fat diet-induced obesity via beta(3)-adrenergic regulation of white adipocyte lipolytic activity. 2013 43


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