Fibrotic Phenotype of Peritumour Mesenteric Adipose Tissue in Human Colon Cancer: A Potential Hallmark of Metastatic Properties.

The impact of tumour associated stroma on cancer metastasis is an emerging field. However, cancer associated genes in peritumoral adipose tissue (pAT) in human colon cancer have not been explored. The aim of this study was to identify differentially expressed genes (DEGs) associated with cancer pathways in mesenteric pAT compared with adjacent adipose tissue. In total, nine patients with colon cancer pathological stage T2/T4 were employed in this study. DEGs were identified in 6 patients employing Nanostring PanCancer Pathway Panel and pathway enrichment analyses were performed. Differential expression of the 5 most up-regulated and 2 down regulated genes was validated with qRT-PCR. Results showed collagen type I alpha 1 chain (COL1A1) p = 0.007; secreted frizzled related protein (SFRP2) p = 0.057; fibroblast growth factor 7 (FGF7) not significant (ns); phospholipase A2, group IIA (PLA2G2A) ns; nerve growth factor receptor (NGFR) ns; lymphoid enhancer binding factor 1 (LEF1) p = 0.03; cadherin 1, Type 1, E-cadherin (epithelial) (CDH1) 0.09. Results have highlighted down-regulation of the Wingless/Integrated (Wnt) pathway in mesenteric pAT compared to distal adipose tissue. Highly upregulated genes in mesenteric pAT were involved in extracellular matrix (ECM)-receptor interactions and focal adhesion. Highly down regulated genes were involved in the cell cycle. Immunohistochemistry revealed differential distribution of COL1A1 showing maximum levels in tumour tissue and gradually decreasing in distant adipose tissue. COL1A1 and down regulation of Wnt pathway may have a role in local invasion and distant metastasis. COL1A1 may represent a stromal prognostic biomarker and therapeutic target in colon cancer.

Hepatic VLDL secretion: DGAT1 determines particle size but not particle number, which can be supported entirely by DGAT2.

We investigated whether, in view of its activity being expressed on both aspects of the endoplasmic reticulum (ER; dual membrane topology), diacylglycerol acyltransferase 1 (DGAT1) plays a distinctive role in determining the triglyceride (TAG) content of VLDL particles secreted by the liver. Mice in which the DGAT1 gene was specifically ablated in hepatocytes (DGAT1-LKO mice) had the same number of VLDL particles (apoB concentration) in the plasma 1 h after Triton 1339 treatment, but these particles were approximately half the size of VLDL particles secreted by control mice and had a proportionately decreased content of TAG, with normal cholesterol and cholesteryl ester contents. Analyses of purified microsomal fractions prepared from 16 h fasted control and DAGT1-LKO mice showed that the TAG/protein ratio in the ER was significantly lower in the latter. Electron micrographs of these livers showed that those from DGAT1-LKO mice did not show the increased lipid content of the smooth ER shown by control livers. The effects of DGAT1- and DGAT2-specific inhibitors on apoB secretion by HepG2 cells showed that DGAT1 is not indispensable for apoB secretion and demonstrated redundancy in the ability of the two enzymes to support apoB secretion. Therefore, our findings show that DGAT1 is essential for the complete lipidation and maturation of VLDL particles within the lumen of the ER, consistent with its dual topology within the ER membrane. In the mouse, DGAT2 can support apoB secretion (particle number) even when TAG availability for full VLDL lipidation is restricted in the absence of DGAT1.

Effects of visfatin on brown adipose tissue energy regulation using T37i cells.

The role of brown adipose tissue (BAT) in pathological states of energy homeostasis and impaired adipocyte function, such as obesity has been a major area of research interest in recent years. Herein, we sought to determine the direct effects of adipokines, visfatin and leptin on BAT thermogenesis. The effects of mouse recombinant visfatin, nicotinamide mononucleotide (NMN) and leptin with or without FK866 were studied on differentiated T37i cells. Treated cells were analyzed for key genes and proteins regulating BAT [UCP-1, PRD1-BF1-RIZ1 homologous domain-containing 16 (PRDM-16), PPARgamma-coactivator-1alpha (PGC-1α) and receptor-interacting protein 140 (RIP-140)] using quantitative PCR and western blot analysis. Data is presented as mean P-values. Both visfatin and leptin had significant concentration dependent effects on thermogenesis in brown pre-adipocytes and at physiological levels, increased uncoupling protein-1 (UCP-1) levels in brown adipocytes. These effects of visfatin were similar to that of nicotinamide mononucleotide (NMN), further strengthening the enzymatic role of visfatin. We also showed that leptin induced UCP-1 mRNA expression and protein production appears to be mediated by visfatin. High concentrations of both visfatin and leptin led to a dramatic decrease in UCP-1 protein levels, supporting the notion that visfatin levels are raised in obesity and that obese people have reduced BAT activity, plausibly through a reduction in UCP-1 levels. Additionally, we found differential regulation of key brown adipogenic genes, specifically, PRD1-BF1-RIZ1 homologous domain-containing 16 (PRDM-16), PPARgamma-coactivator-1alpha (PGC-1α) and receptor-interacting protein 140 (RIP-140) by visfatin. Our observations provide novel insights in the potential actions of visfatin in BAT.

Protective actions of globular and full-length adiponectin on human endothelial cells: novel insights into adiponectin-induced angiogenesis.

BACKGROUND/AIMS: Adiponectin levels are decreased in diabetes and atherosclerosis. Coexisting hyperglycaemia and systemic inflammation predisposes to dysregulated angiogenesis and vascular disease. We investigated the effect of globular adiponectin (gAd) and full-length adiponectin (fAd) on angiogenesis and pro-angiogenic molecules, i.e. matrix metalloproteinase (MMP)-2, MMP-9 and vascular endothelial growth factor (VEGF), in human microvascular endothelial cells (HMEC-1). METHODS: Angiogenesis was assessed by studying capillary tube formation in HMEC-1 on growth factor-reduced Matrigel. Endothelial cell migration assay was performed in a modified Boyden chamber. RESULTS: Endothelial cell proliferation, in vitro migration and angiogenesis were significantly increased by gAd (mediated by AdipoR1, AMPK-Akt pathways), and gAd significantly increased MMP-2, MMP-9 and VEGF expression levels. The effect of gAd on VEGF appears to be mediated by AdipoR1, whilst the effect of gAd on MMP-2 and MMP-9 appears to be mediated by AdipoR1 and AdipoR2. Only endothelial cell proliferation was significantly increased by fAd in human microvascular endothelial cells and appears to be mediated by AdipoR2. No significant effects on MMP-2, MMP-9 and VEGF were observed. Importantly, gAd decreased glucose and C-reactive protein-induced angiogenesis with a concomitant reduction in MMP-2, MMP-9 and VEGF in HMEC-1 cells. CONCLUSION: We report novel insights into the mechanisms of adiponectin on angiogenesis.

Identification of chemerin receptor (ChemR23) in human endothelial cells: chemerin-induced endothelial angiogenesis.

Chemerin acting via its distinct G protein-coupled receptor CMKLR1 (ChemR23), is a novel adipokine, circulating levels of which are raised in inflammatory states. Chemerin shows strong correlation with various facets of the metabolic syndrome; these states are associated with an increased incidence of cardiovascular disease (CVD) and dysregulated angiogenesis. We therefore, investigated the regulation of ChemR23 by pro-inflammatory cytokines and assessed the angiogenic potential of chemerin in human endothelial cells (EC). We have demonstrated the novel presence of ChemR23 in human ECs and its significant up-regulation (P<0.001) by pro-inflammatory cytokines, TNF-alpha, IL-1beta and IL-6. More importantly, chemerin was potently angiogenic, as assessed by conducting functional in-vitro angiogenic assays; chemerin also dose-dependently induced gelatinolytic (MMP-2 & MMP-9) activity of ECs (P<0.001). Furthermore, chemerin dose-dependently activated PI3K/Akt and MAPKs pathways (P<0.01), key angiogenic and cell survival cascades. Our data provide the first evidence of chemerin-induced endothelial angiogenesis and MMP production and activity.

Visfatin induces human endothelial VEGF and MMP-2/9 production via MAPK and PI3K/Akt signalling pathways: novel insights into visfatin-induced angiogenesis.

AIMS: Visfatin is a novel adipokine whose plasma concentrations are altered in obesity and obesity-related disorders; these states are associated with an increased incidence of cardiovascular disease. We therefore investigated the effect of visfatin on vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMP-2, MMP-9) production and the potential signalling cascades. METHODS AND RESULTS: In human umbilical vein endothelial cells (HUVECs), visfatin significantly and dose-dependently up-regulated gene expression and protein production of VEGF and MMPs and down-regulated expression of tissue inhibitors of MMPs (TIMP-1 and TIMP-2). The gelatinolytic activity of MMPs (analysed by zymography) correlated with mRNA and western blot findings. Interestingly, visfatin significantly up-regulated VEGF receptor 2 expression. Inhibition of VEGFR2 and VEGF [by soluble FMS-like tyrosine kinase-1 (sFlt1)] down-regulated visfatin-induced MMP induction. Visfatin induced dose- and time-dependent proliferation and capillary-like tube formation. Importantly, visfatin was noted to have anti-apoptotic effects. In HUVECs, visfatin dose-dependently activated PI3K/Akt (phosphatidylinositol 3-kinase/Akt) and ERK(1/2) (extracellular signal-regulated kinase) pathways. The functional effects and MMP/VEGF induction were shown to be dependent on the MAPK/PI3K-Akt/VEGF signalling pathways. Inhibition of PI3K/Akt and ERK(1/2) pathways led to significant decrease of visfatin-induced MMP and VEGF production and activation, along with significant reduction in endothelial proliferation and capillary tube formation. CONCLUSION: Our data provide the first evidence of visfatin-induced endothelial VEGF and MMP production and activity. Further, we show for the first time the involvement of the MAPK and PI3K/Akt signalling pathways in mediating these actions, as well as endothelial cell proliferation. Collectively, our findings provide novel insights into visfatin-induced endothelial angiogenesis.

Chemerin induces endothelial cell inflammation: activation of nuclear factor-kappa beta and monocyte-endothelial adhesion.

Chemerin, a chemoattractant protein, acts via a G-protein coupled chemokine receptor, i.e. Chemokine like Receptor 1/ChemR23; levels of which are elevated in pro-inflammatory states such as obesity and type 2 diabetes mellitus (T2DM). Obesity and T2DM patients are at high risk of developing cardiovascular disorders such as atherosclerosis. We have reported that chemerin induces human endothelial cell angiogenesis and since dysregulated angiogenesis and endothelial dysfunction are hallmarks of vascular disease; we sought to determine the effects of chemerin on monocyte-endothelial adhesion, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), a critical pro-inflammatory transcription factor. Human endothelial cells were transfected with pNF-kappaB-Luc plasmid. Chemerin induced NF-κB activation via the MAPK and PI3K/Akt pathways. Western blot analyses and monocyte-endothelial adhesion assay showed that chemerin increased endothelial cell adhesion molecule expression and secretion, namely E-selectin (Endothelial Selectin), VCAM-1 (Vascular Cell Adhesion Molecule-1) and ICAM-1 (Intracellular Adhesion Molecule-1), leading to enhancement of monocyte-endothelial adhesion. Additionally, we showed a synergistic response of the pro-inflammatory mediator, Interleukin-1ß with chemerin induced effects. Chemerin plays an important role in endothelial inflammation, as it induces monocyte-endothelial adhesion, a critical step in the development of atherosclerosis.

Role of tissue microenvironment resident adipocytes in colon cancer.

Colorectal cancer (CRC) is a multifactorial disease characterized by several genetic and epigenetic alterations occurring in epithelial cells. It is increasingly recognized that tumour progression is also regulated by tumour microenvironment (TME). The bidirectional cross-talk between tumour resident adipocytes and cancer cells within TME has been proposed as active contributor to carcinogenesis. Tumour resident adipocytes exhibit an activated phenotype characterized by increased secretion of pro-tumorigenic factors (angiogenic/inflammatory/immune) which contribute to cancer cell proliferation, invasion, neoangiogenesis, evasion of immune surveillance and therapy resistance. Furthermore, adipocytes represent a fuel rich source for increasing energy demand of rapidly proliferating tumour cells. Interestingly, a relationship between obesity and molecular variants in CRC has recently been identified. Whether adipose tissue promotes cancer progression in subsets of molecular phenotypes or whether local tissue adipocytes are involved in inactivation of tumour suppressor genes and/or activation of oncogenes still needs to be explored. This editorial highlights the major findings related to cross-talk between adipocytes and colon cancer cells and how local paracrine interactions may promote cancer progression. Furthermore, we provide future strategies in studying colonic TME which could provide insights in bidirectional cross-talk mechanisms between adipocytes and colonic epithelial cells. This could enable to decipher critical signalling pathways of both early colonic carcinogenesis and cancer progression.

Differential effects of leptin and adiponectin in endothelial angiogenesis.

Obesity is a major health burden with an increased risk of cardiovascular morbidity and mortality. Endothelial dysfunction is pivotal to the development of cardiovascular disease (CVD). In relation to this, adipose tissue secreted factors termed "adipokines" have been reported to modulate endothelial dysfunction. In this review, we focus on two of the most abundant circulating adipokines, that is, leptin and adiponectin, in the development of endothelial dysfunction. Leptin has been documented to influence a multitude of organ systems, that is, central nervous system (appetite regulation, satiety factor) and cardiovascular system (endothelial dysfunction leading to atherosclerosis). Adiponectin, circulating at a much higher concentration, exists in different molecular weight forms, essentially made up of the collagenous fraction and a globular domain, the latter being investigated minimally for its involvement in proinflammatory processes including activation of NF-κß and endothelial adhesion molecules. The opposing actions of the two forms of adiponectin in endothelial cells have been recently demonstrated. Additionally, a local and systemic change to multimeric forms of adiponectin has gained importance. Thus detailed investigations on the potential interplay between these adipokines would likely result in better understanding of the missing links connecting CVD, adipokines, and obesity.

Novel insights into the cardio-protective effects of FGF21 in lean and obese rat hearts.

AIMS: Fibroblast growth factor 21 (FGF21) is a hepatic metabolic regulator with pleotropic actions. Its plasma concentrations are increased in obesity and diabetes; states associated with an increased incidence of cardiovascular disease. We therefore investigated the direct effect of FGF21 on cardio-protection in obese and lean hearts in response to ischemia. METHODS AND RESULTS: FGF21, FGF21-receptor 1 (FGFR1) and beta-Klotho (ßKlotho) were expressed in rodent, human hearts and primary rat cardiomyocytes. Cardiac FGF21 was expressed and secreted (real time RT-PCR/western blot and ELISA) in an autocrine-paracrine manner, in response to obesity and hypoxia, involving FGFR1-ßKlotho components. Cardiac-FGF21 expression and secretion were increased in response to global ischemia. In contrast ßKlotho was reduced in obese hearts. In isolated adult rat cardiomyocytes, FGF21 activated PI3K/Akt (phosphatidylinositol 3-kinase/Akt), ERK1/2(extracellular signal-regulated kinase) and AMPK (AMP-activated protein kinase) pathways. In Langendorff perfused rat [adult male wild-type wistar] hearts, FGF21 administration induced significant cardio-protection and restoration of function following global ischemia. Inhibition of PI3K/Akt, AMPK, ERK1/2 and ROR-α (retinoic-acid receptor alpha) pathway led to significant decrease of FGF21 induced cardio-protection and restoration of cardiac function in response to global ischemia. More importantly, this cardio-protective response induced by FGF21 was reduced in obesity, although the cardiac expression profiles and circulating FGF21 levels were increased. CONCLUSION: In an ex vivo Langendorff system, we show that FGF21 induced cardiac protection and restoration of cardiac function involving autocrine-paracrine pathways, with reduced effect in obesity. Collectively, our findings provide novel insights into FGF21-induced cardiac effects in obesity and ischemia.

Metformin increases the novel adipokine adipolin/CTRP12: role of the AMPK pathway.

Adipolin is a novel adipokine with anti-inflammatory and glucose-lowering properties. Lower levels of adipolin are found in obese and diabetic mice. Polycystic ovary syndrome (PCOS) is a pro-inflammatory state associated with obesity and diabetes. To date, there are no human studies on adipolin. Therefore, we measured serum (ELISA) and adipose tissue adipolin mRNA expression (RT-PCR) and protein concentrations (western blotting) in PCOS and control subjects. We also investigated the ex vivo effect of glucose and metformin on adipolin protein production in human subcutaneous adipose tissue explants. We report novel data that serum and subcutaneous adipose tissue adipolin mRNA expression and protein concentrations were significantly lower in women with PCOS compared with control subjects. Furthermore, Spearman's rank analysis showed that serum adipolin concentrations were significantly negatively correlated with BMI, waist-to-hip ratio, and glucose (P<0.05). However, when subjected to multiple regression analysis, none of these variables were predictive of serum adipolin concentrations (P>0.05). Also, subcutaneous adipose tissue adipolin mRNA expression and protein concentrations were only significantly negatively correlated with glucose (P<0.05). No significant correlations were found with omental adipose tissue adipolin mRNA expression and protein concentrations (P>0.05). Moreover, glucose profoundly reduced and metformin significantly increased adipolin protein production in human adipose tissue explants respectively. Importantly, metformin's effects appear to be via the AMP-activated protein kinase signaling pathway.

Metformin increases the novel adipokine cartonectin/CTRP3 in women with polycystic ovary syndrome.

CONTEXT: Recently cartonectin was reported as a novel adipokine, with lower levels in diet-induced obese mice, glucose-lowering effects, and antiinflammatory and cardioprotective properties. Polycystic ovary syndrome (PCOS) is a proinflammatory state associated with obesity, diabetes, dyslipidemia, and cardiovascular complications. OBJECTIVES: The objective of the study was to investigate cartonectin levels and regulation in sera and adipose tissue (AT) as well as the effects of metformin of women with PCOS and control subjects. DESIGN: This was a cross-sectional study [PCOS (n = 83) and control (n = 39) subjects]. Real-time PCR and Western blotting were used to assess mRNA and protein expression of cartonectin. Serum cartonectin was measured by an ELISA. RESULTS: Serum and omental adipose tissue cartonectin were significantly lower in women with PCOS compared with control subjects (P < .05 and P < .01, respectively). Furthermore, cartonectin showed a significant negative association with body mass index, waist to hip ratio, glucose, insulin, total cholesterol, low-density lipoprotein-cholesterol, triglycerides, High sensitivity C-reactive protein (hs-CRP) and intima-media thickness (P < .05 and P < .01, respectively); in multiple regression analyses, triglycerides (P =.040) and hs-CRP (P = .031) were predictive of cartonectin levels (P < .05). After 6 months of metformin treatment, there was an associated increase in serum cartonectin (P < .05). Importantly, changes in hs-CRP were significantly negatively correlated with changes in serum cartonectin (P = .033). Finally, cartonectin protein production and secretion into conditioned media were significantly increased by metformin in control human omental AT explants (P < .05). CONCLUSIONS: Serum and omental AT cartonectin are lower in women with PCOS. Metformin treatment increases serum cartonectin levels in these women and in omental AT explants.

The anti-atherogenic aspect of metformin treatment in insulin resistant women with the polycystic ovary syndrome: role of the newly established pro-inflammatory adipokine Acute-phase Serum Amyloid A; evidence of an adipose tissue-monocyte axis.

OBJECTIVE: Acute-phase Serum Amyloid A (ASAA) is a novel pro-inflammatory adipokine, increased in obese, insulin resistant subjects. Polycystic ovary syndrome (PCOS) is associated with inflammation and atherosclerosis. We assessed sera, adipose tissue (AT) mRNA and protein levels of ASAA of PCOS women and matched controls. Ex vivo regulation of AT ASAA by d-glucose, effects of metformin treatment on circulating ASAA in PCOS subjects and effects of sera from normal and PCOS subjects (before and after metformin) on ASAA production (THP-1 macrophages) were also studied. METHODS AND RESULTS: Circulating ASAA (ELISA), subcutaneous and omental AT ASAA mRNA (RT-PCR) and protein (western blotting) were significantly higher in PCOS women (P<0.05). In AT explants, glucose significantly increased ASAA production and secretion (P<0.05, P<0.01). Furthermore, ASAA production (THP-1 macrophages) was significantly greater by sera from PCOS women compared to controls (P<0.01). ASAA protein production was significantly decreased by sera from PCOS women following 6 months of metformin treatment (P<0.05). After 6 months of metformin treatment, there was a significant decrease in circulating ASAA (P<0.05). Importantly, changes in intima media thickness were predictive of changes in circulating ASAA (P=0.034). CONCLUSION: Serum and AT ASAA are increased in PCOS women and are elevated by glucose. Metformin treatment decreases serum ASAA in these women. An adipose tissue-monocyte axis may be pivotal in the pathogenesis of inflammation and atherosclerosis. ASAA may be a valuable diagnostic marker in the management of dysmetabolic states including PCOS.

Fibroblast growth factor 21 (FGF21) in human cerebrospinal fluid: relationship with plasma FGF21 and body adiposity.

OBJECTIVE: Reports of increased circulating fibroblast growth factor 21 (FGF21) levels in obesity indicate that FGF21 may be implicated in body weight homeostasis. We sought to investigate the existence of FGF21 in human cerebrospinal fluid (CSF) and, if present, the relationship between CSF FGF21 with body adiposity and metabolic parameters. RESEARCH DESIGN AND METHODS: CSF and corresponding plasma FGF21 were measured by an enzyme-linked immunosorbent assay (18 men and 20 women, aged 19-80 years, and BMI 16.2-38.1 kg/m(2)) and correlated to body adiposity and metabolic parameters. RESULTS: CSF and plasma FGF21 increased in particular with rising BMI and fat mass. In CSF, FGF21 was detectable at concentrations ~40% that of plasma levels. CSF and plasma FGF21 levels were significantly positively correlated with BMI and fat mass, body weight, plasma insulin, and homeostasis model assessment of insulin resistance. Plasma FGF21 levels were significantly negatively correlated with plasma adiponectin. When subjected to multiple regression analysis, only fat mass was predictive of plasma FGF21 (ß = 0.758; P = 0.004) and CSF FGF21 (ß = 0.767; P = 0.007). The CSF-to-plasma FGF21 ratio was significantly negatively correlated with BMI, fat mass, and plasma FGF21. Subjects in the highest plasma FGF21 quintile had a lower CSF-to-plasma FGF21 ratio (12.7% [9.7-14.9%]) compared with those in the lowest plasma FGF21 quintile (94.7% [37.3-99.8%]) (P < 0.01). CONCLUSIONS: Our observations have important implications with respect to the potential central actions of FGF21. Future research should seek to clarify whether FGF21 would be beneficial in the management of obesity and its metabolic complications.

Metformin treatment exerts antiinvasive and antimetastatic effects in human endometrial carcinoma cells.

CONTEXT: Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women associated with an increased risk of endometrial hyperplasia. We sought to study the effects of metformin treatment (widely used in the management of PCOS women) on human endometrial adenocarcinoma cells. OBJECTIVES: To study the effects of metformin treatment on in vitro invasion and metastasis in human endometrial adenocarcinoma cells. Also, given the link between inflammation with endometrial cancer invasion and metastasis, we explored the roles of nuclear factor-κB (NF-κB), matrix metalloproteinases (MMPs) as well as v-akt murine thymoma viral oncogene homolog 1 (Akt) and extracellular signal-regulated kinases (Erk(1/2)) signaling pathways. DESIGN: Sera were obtained from PCOS and control subjects. In vitro invasion were assessed in human endometrial cells (ECC-1 cells) by wound-healing motility and migration assays. NF-κB was studied by stably transfecting ECC-1 cells with a cis-reporter plasmid containing luciferase reporter gene linked to five repeats of NF-κB binding sites. The gelatinolytic activities of secreted MMP-2/9 in conditioned media were measured by gelatin zymography. Akt and Erk(1/2) phosphorylation were assessed by Western blotting. RESULTS: In vitro invasion in ECC-1 cells was significantly attenuated by sera from PCOS women after 6 months of metformin treatment (850 mg twice daily) compared to matched controls (P < 0.01). These effects appear to be associated with NF-κB, MMP-2/9, as well as Akt and Erk(1/2) pathways that are known to be important regulators of inflammation, tumor invasion and metastasis. CONCLUSIONS: Metformin, potentially, may serve as adjuvant treatment in the management of patients with endometrial cancer.

Diurnal variation and effect of insulin on circulating high molecular weight (HMW) adiponectin and NF-κB activity in human endothelial cells.

OBJECTIVE: To study the diurnal variation and the effect of insulin on adiponectin multimers and nuclear factor-kappaB (NF-κB) activity in human endothelial cells. METHODS AND RESULTS: We utilized a prolonged insulin-glucose infusion in six healthy human subjects. HMW and total adiponectin levels were higher in the morning and lower at night; NF-κB activities in serum treated human microvascular endothelial cells (HMEC-1) cells were lower in the morning and higher at night. Hyperinsulinemic induction significantly decreased HMW and total adiponectin levels but increased NF-κB activity in serum treated HMEC-1 cells (P<0.05, P<0.01). There were no significant changes to MMW and LMW adiponectin levels (P>0.05). CONCLUSION: Circadian rhythm of HMW adiponectin and NF-κB activity are altered by hyperinsulinemia providing novel insights adiponectin and NF-κB biology, which may be pertinent to insulin resistant states, e.g. obesity and type 2 diabetes mellitus.

Omentin: a novel link between inflammation, diabesity, and cardiovascular disease.

Obesity has reached pandemic proportions and is associated with serious cardiometabolic sequelae including insulin resistance, diabetes, dyslipidemia, hypertension, and cardiovascular disease, where adipose tissue-secreted cytokines, that is, adipokines, have been implicated in these processes. Omentin is a novel adipokine preferentially produced by visceral adipose tissue with insulin-sensitizing effects, where circulating levels are decreased in insulin-resistant states, for example, obesity and diabetes. With respect to vascular biology, omentin causes vasodilatation of blood vessels and attenuates C-reactive protein-induced angiogenesis potentially via the nuclear factor B signaling pathway, a potent proinflammatory signaling pathway. Thus, omentin may have beneficial effects on the metabolic syndrome and could potentially be used as a biologic marker and/or pharmacologic agent in this respect.

Metformin treatment may increase omentin-1 levels in women with polycystic ovary syndrome.

OBJECTIVE: Polycystic ovary syndrome (PCOS) is associated with the metabolic syndrome. Decreased omentin-1 levels are associated with obesity and diabetes. To study the effects of metformin treatment on omentin-1 levels in PCOS subjects and effects of omentin-1 on in vitro migration and angiogenesis. RESEARCH DESIGN AND METHODS: Serum omentin-1 was measured by ELISA. Angiogenesis was assessed by studying capillary tube formation in human microvascular endothelial cells (HMEC-1) on growth factor reduced Matrigel. Endothelial cell migration assay was performed in a modified Boyden chamber. Nuclear factor-κB (NF-κB) was studied by stably transfecting HMEC-1 cells with a cis-reporter plasmid containing luciferase reporter gene linked to five repeats of NF-κB binding sites. Akt phosphorylation was assessed by Western blotting. RESULTS: Serum omentin-1 was significantly lower in PCOS women (P < 0.05). After 6 months of metformin treatment, there was a significant increase in serum omentin-1 (P < 0.01). Importantly, changes in hs-CRP were significantly negatively correlated with changes in serum omentin-1 (P = 0.036). In vitro migration and angiogenesis were significantly increased in serum from PCOS women (P < 0.01) compared with matched control subjects; these effects were significantly attenuated by metformin treatment (P < 0.01) plausibly through the regulation of omentin-1 levels via NF-κB and Akt pathways. CRP and VEGF induced in vitro migration, and angiogenesis was significantly decreased by omentin-1. CONCLUSIONS: Increases in omentin-1 levels may play a role but are not sufficient to explain the decreased inflammatory and angiogenic effects of sera from metformin-treated PCOS women.

A novel role for the adipokine visfatin/pre-B cell colony-enhancing factor 1 in prostate carcinogenesis.

Adipose tissue is now well established as an endocrine organ and multiple hormones termed 'adipokines' are released from it. With the rapidly increasing obese population and the increased risk mortality from prostate cancer within the obese population we looked to investigate the role of the adipokine visfatin in LNCaP and PC3 prostate cancer cell lines. Using immunohistochemistry and immunocytochemistry we demonstrate visfatin expression in LNCaP (androgen-sensitive) and PC3 (androgen-insensitive) human prostate cancer cell lines as well as human prostate cancer tissue. Additionally, we show that visfatin increases PC3 cell proliferation and demonstrate the activation of the MAPKs ERK-1/2 and p38. Moreover we also demonstrate that visfatin promotes the expression and activity of MMP-2/9 which are important proteases involved in the breakdown of the extracellular matrix, suggesting a possible role for visfatin in prostate cancer metastases. These data suggest a contributory and multifunctional role for visfatin in prostate cancer progression, with particular relevance and emphasis in an obese population.

Pre-B cell colony enhancing factor (PBEF)/visfatin induces secretion of MCP-1 in human endothelial cells: role in visfatin-induced angiogenesis.

OBJECTIVES: Visfatin and Monocyte-Chemoattractant-Protein-1 (MCP-1) are elevated in cardiovascular pathologies, insulin-resistant and diabetic states. Visfatin has been reported to exhibit pro-angiogenic actions in human endothelial cells. Given MCP-1's well described pro-angiogenic properties we sought to study the potential interaction between visfatin and MCP-1 in human endothelial cells. We also explored the possible autocrine/paracrine mechanisms governing this potential interaction; specifically we looked at the effect of visfatin on MCP-1's putative receptor (CCR2 receptor) in human endothelial cells. METHODS AND RESULTS: Using in vitro angiogenic assays (capillary tube formation and migration), Western blotting and RT-PCR, we found that visfatin, dose-dependently, induced MCP-1 as well as CCR2 levels. We also studied the involvement of PI3Kinase, MAPKinase and NF-kappaB pathways in visfatin induced MCP-1/CCR2 levels by employing LY294002, U0126 and BAY11-7085, respectively. We found the increase in MCP-1 and CCR2 levels by visfatin were negated by LY294002 and BAY11-7085, but not with U0126, suggesting the crucial role of PI3Kinase and NF-kappaB pathways in visfatin induced MCP-1 and its autocrine regulation via the CCR2 receptor. Finally, we consolidate the role of MCP-1 in visfatin-induced angiogenesis by employing CCR2 antagonist (RS-102895) and MCP-1 neutralising antibody, respectively. CONCLUSIONS: Our novel data reveal that MCP-1 is pivotal in modulating visfatin-induced angiogenesis via NF-kappaB and PI3Kinase pathways. Furthermore, our findings elucidate the potential influence of autocrine/paracrine mechanisms (via the CCR2 receptor) underlying visfatin's angiogenic effects through MCP-1.