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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.

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-1β 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.

Introduction The impact of tumour associated stroma on cancer cell invasion and metastasis is an attractive emerging field. Using Nanostring Pancancer pathway we have previously identified pro-fibrotic genes collagen type 1, alpha 1 (COL1A1), fibroblast growth factor 7 (FGF7) and secreted frizzled related protein 2 (SFRP2) significantly up regulated in human colon cancer peritumour adipose tissue compared to distal adipose tissue. Aim of this study was to evaluate the effect of Rosiglitazone, a peroxisome proliferator-activated receptor gamma (PPARG) agonist known to have anti fibrogenic properties, on COL1A1, FGF7 and SFRP2. Methods The effect of Rosiglitazone on COL1A1 and SFRP2 was evaluated employing in vitro co-culture systems. 3T3 L1 murine adipocytes were co-cultured with HCT 116 colon cancer cells with and without 1 nM Rosiglitazone for 72 hours. COL1A1, FGF7 and SFRP2 expression were evaluated using quantitative real time-polymerase chain reaction (qRT-PCR). Statistical analysis was performed using paired Student’s t-test with a cut-off of p-value Results Both COL1A1 and SFRP2 resulted significantly downregulated in co-cultured 3T3 L1 adipocytes treated with Rosiglitazone compared to untreated co-cultured 3T3 L1 adipocytes (20 fold change, p=0.02; 3.3 fold change, p=0.01 respectively). We did not observe any significant effect of Rosiglitazone on FGF7 expression in treated 3T3 L1 adipocytes compared to untreated adipocytes. Conclusion Our results have demonstrated significant down regulation of pro-fibrotic genes COL1A1 and SFRP2 in mature adipocytes induced by Rosiglitazone. Rosiglitazone may represent a novel therapeutic agent in stromal targeted therapy in colon cancer.

Introduction Dysfunctional adipose tissue has emerged as a key contributor to colorectal cancer. However, the role of peritumoral adipose tissue (pAT) in colon cancer has not been widely investigated. Aim of this study is to identify differentially expressed genes (DEGs) associated with cancer pathways in peritumoral adipose tissue compared with adjacent normal adipose tissue in human colon cancer. Methods Fresh peritumoral and distal adipose tissue samples were collected from 6 patients undergoing surgery for colon cancer stage T3/T4. DEGs were identified employing Nanostring PanCancer Pathway Panel including 770 cancer-associated genes. Criteria for differential expression included p-value Results A total of 64/770 DEGs were identified in peritumoral adipose tissue compared to distal adipose tissue. Up-regulated genes (28.1%) included COL1A1, SFRP2, FGF7, PLA2G2A, NGFR and SFRP2. Down regulated genes (71.9%) included LEF1 and CDH1. Differential expression was validated with qRT-PCR (COL1A1 p=0.007; SFRP2 p=0.057; FGF7 ns; PLA2G2A ns; NGFR ns; LeF1 p=0.03; CDH1 p=0.09). IHC revealed differential distribution of COL1A1 showing maximum expression in tumor tissue decreasing at more distant sites. Conclusion Our results have shown altered cancer associated pathways in peritumour stromal compartment, including down-regulation of Wingless/Integrated (WNT) pathway. Furthermore, we have identified significant up regulation of COL1A1 in peritumour adipose tissue compared to distal adipose tissue. COL1A1 may have a role in local invasion and distant metastasis, possibly mediated by SFRP2, a known pro-collagen c proteinase enhancer and WNT antagonist. SFRP2 and COL1A1 may represent potential stromal therapeutic targets in colon cancer.

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. \ud 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-1) and receptor-interacting protein 140 (RIP-140)] using quantitative PCR and western blot analysis. Data is presented as mean P-values. \ud 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-1) and receptor-interacting protein 140 (RIP-140) by visfatin. Our observations provide novel insights in the potential actions of visfatin in BAT.

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.

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.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.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.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).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.

This editorial refers to an article by R. Adya et al . [2][1] published in Cardiovascular Research in 2008 (see [Box 1][2]). It is accompanied by an editorial by J. Waltenberger and E. Pardali (doi:10.1093/cvr/cvs180) as part of this Spotlight on Landmark Papers in Cardiovascular Research . We are members of the ‘Metabolic and Vascular Research Group’, Warwick Medical School, UK, interested in novel adipokines proposed to have a functional interplay with the cardiovascular system. Since the discovery of visfatin/pre-B cell colony-enhancing factor (PBEF)/NAMPT in 2004,1 researchers world-wide have contributed to our present understanding of this ever-elusive molecule. We had published previously on visfatin-mediated effects in human endothelial cells contributing to endothelial angiogenesis.2 In this short editorial, we aim to briefly recapitulate the historical perspectives and previous contributions in the field of visfatin research. PBEF (also termed nicotinamide phosphoribosyl transferase, NAMPT, or visfatin) was discovered as a novel cytokine secreted by activated human lymphocytes that functions as a growth factor for early B cell maturation.1 Despite the absence of a signal peptide required for secretion, PBEF/visfatin has been demonstrated to circulate freely in detectable ranges in plasma and serum, functioning as a classical cytokine.3,4 Pro-inflammatory properties of visfatin have been widely documented in several in vitro and in vivo studies. Earlier investigations reported both the presence of visfatin (PBEF) and its effects in inducing IL-6 and IL-8 cytokine release from amnion-like epithelial (WISH) cells and foetal membrane explants.5,6 Later studies elucidated the role of visfatin in delaying neutrophil apoptosis in experimental inflammation/clinical sepsis7 and thrombin-induced … [1]: #ref-2 [2]: #F3

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.

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/m2) 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 (β = 0.758; P = 0.004) and CSF FGF21 (β = 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.

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-α, IL-1β 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.

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.

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-κB 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-κB 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-κB 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.

OBJECTIVE To assess chemerin levels and regulation in sera and adipose tissue from women with polycystic ovary syndrome (PCOS) and matched control subjects. RESEARCH DESIGN AND METHODS Real-time RT-PCR and Western blotting were used to assess mRNA and protein expression of chemerin. Serum chemerin was measured by enzyme-linked immunosorbent assay. We investigated the in vivo effects of insulin on serum chemerin levels via a prolonged insulin-glucose infusion. Ex vivo effects of insulin, metformin, and steroid hormones on adipose tissue chemerin protein production and secretion into conditioned media were assessed by Western blotting and enzyme-linked immunosorbent assay, respectively. RESULTS Serum chemerin, subcutaneous, and omental adipose tissue chemerin were significantly higher in women with PCOS (n = 14; P < 0.05, P < 0.01). Hyperinsulinemic induction in human subjects significantly increased serum chemerin levels (n = 6; P < 0.05, P < 0.01). In adipose tissue explants, insulin significantly increased (n = 6; P < 0.05, P < 0.01) whereas metformin significantly decreased (n = 6; P < 0.05, P < 0.01) chemerin protein production and secretion into conditioned media, respectively. After 6 months of metformin treatment, there was a significant decrease in serum chemerin (n = 21; P < 0.01). Importantly, changes in homeostasis model assessment–insulin resistance were predictive of changes in serum chemerin (P = 0.046). CONCLUSIONS Serum and adipose tissue chemerin levels are increased in women with PCOS and are upregulated by insulin. Metformin treatment decreases serum chemerin in these women.

Visfatin is an adipogenic adipokine with increased levels in obesity, properties common to leptin. Thus, leptin may modulate visfatin production in adipose tissue (AT). Therefore, we investigated the effects of leptin on visfatin levels in 3T3-L1 adipocytes and human/murine AT, with or without a leptin antagonist. The potential signaling pathways and mechanisms regulating visfatin production in AT was also studied. Real-time RT-PCR and Western blotting were used to assess the relative mRNA and protein expression of visfatin. ELISA was performed to measure visfatin levels in conditioned media of AT explants, and small interfering RNA technology was used to reduce leptin receptor expression. Leptin significantly (P < 0.01) increased visfatin levels in human and murine AT with a maximal response at leptin 10−9m, returning to baseline at leptin 10−7m. Importantly, ip leptin administration to C57BL/6 ob/ob mice further supported leptin-induced visfatin protein production in omental AT (P < 0.05). Additionally, soluble leptin receptor levels rose with concentration dependency to a maximal response at leptin 10−7m (P < 0.01). The use of a leptin antagonist negated the induction of visfatin and soluble leptin receptor by leptin. Furthermore, leptin-induced visfatin production was significantly decreased in the presence of MAPK and phosphatidylinositol 3-kinase inhibitors. Also, when the leptin receptor gene was knocked down using small interfering RNA, leptin-induced visfatin expression was significantly decreased. Thus, leptin increases visfatin production in AT in vivo and ex vivo via pathways involving MAPK and phosphatidylinositol 3-kinase signaling. The pleiotropic effects of leptin may be partially mediated by visfatin.

OBJECTIVE—Polycystic ovary syndrome (PCOS) is associated with insulin resistance and obesity. Recent studies have shown that plasma omentin-1 levels decrease with obesity. Currently, no data exist on the relative expression and regulation of omentin-1 in adipose tissue of women with PCOS. The objective of this study was to assess mRNA and protein levels of omentin-1, including circulating omentin-1, in omental adipose tissue of women with PCOS and matched control subjects. Ex vivo and in vivo regulation of adipose tissue omentin-1 was also studied. RESEARCH DESIGN AND METHODS—Real-time RT-PCR and Western blotting were used to assess mRNA and protein expression of omentin-1. Plasma omentin-1 was measured by enzyme-linked immunosorbent assay. The effects of d-glucose, insulin, and gonadal and adrenal steroids on adipose tissue omentin-1 were analyzed ex vivo. The in vivo effects of insulin (hyperinsulinemia) on omentin-1 levels were also assessed by a prolonged insulin-glucose infusion. RESULTS—In addition to decreased plasma omentin-1 levels in women with PCOS (P < 0.05), compared with control subjects, there was significantly lower levels of omentin-1 mRNA (P < 0.01) and protein (P < 0.05) in omental adipose tissue of women with PCOS (P < 0.01). Furthermore, in omental adipose tissue explants, insulin and glucose significantly dose-dependently decreased omentin-1 mRNA expression, protein levels, and secretion into conditioned media (P < 0.05, P < 0.01). Also, hyperinsulinemic induction in healthy subjects significantly reduced plasma omentin-1 levels (P < 0.01). CONCLUSIONS—Our novel findings reveal that omentin-1 is downregulated by insulin and glucose. These may, in part, explain the decreased omentin-1 levels observed in our overweight women with PCOS.

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 ERK1/2 (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 ERK1/2 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.

Initially described as an inert fat store, adipose tissue (AT) has been extensively studied in recent years and shown to have multifaceted roles in appetite regulation, vascular homeostasis, energy balance and systemic inflammation in chronic diseases. Composed mainly of adipocytes and stromal vascular fraction (SVCs), comprising preadipocytes, macrophages, mesenchymal stem cells (MSCs), T cells, B cells, mast cells and endothelial progenitor cells (EPCs), AT performs an endocrine role in secretion of growth factors and cytokines (termed adipocytokines). AT is extensively vascularized and, as in other tissues and organs, the growth and maintenance of AT is critically dependent on angiogenic processes. The microvasculature network surrounding the adipocytes provides efficient pathways for crosstalk with the surrounding environment. AT undergoes constant expansion and shrinkage during its entire life span. To cope with this increased metabolic demand during expansion, AT vasculature undergoes extensive remodelling, and changes to vessel density are observed. To facilitate these processes, AT secretes angiogenic/growth factors. Dysregulation in the secretion of these factors is known to play an important role in obesity and insulin-resistant states. In this article we will discuss novel therapeutic strategies to combat obesity and inflammation by inducing changes to the AT vascular network.

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-κβand 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.

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.

OBJECTIVE—Visfatin is elevated in obesity and type 2 diabetes and is thought to be an inflammatory mediator within atherosclerotic lesions and to induce gelatinase activity. We investigated the activation of nuclear factor-κB (NF-κB), a well-known proinflammatory transcription factor, by visfatin in endothelial cells. RESEARCH DESIGN AND METHODS—Human endothelial cells were transfected with pNF-κB-Luc plasmid. Using quantitative PCR, Western blot analysis, and gelatin zymography, we studied NF-κB signaling in gelatinase-mediated vascular inflammation by visfatin using the NF-κB inhibitor BAY 11-7085. RESULTS—Visfatin significantly increased NF-κB transcriptional activity (P < 0.001). We also found a significant inhibition of tumor necrosis factor-α (TNF-α)-induced NF-κB activity by visfatin (P < 0.001). Furthermore, the NF-κB inhibitor significantly negated visfatin-induced matrix metalloproteinase (MMP)-2/9 mRNA expression, protein levels, and gelatinolytic activity (P < 0.001). CONCLUSIONS—Visfatin-induced NF-κB signaling in human endothelial cells affects the activation of gelatinases MMP-2 and -9, suggesting an important role of visfatin in the pathogenesis of vascular inflammation in obesity and type 2 diabetes.

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 (PP>0.05). Also, subcutaneous adipose tissue adipolin mRNA expression and protein concentrations were only significantly negatively correlated with glucose (PP>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.

Polycystic ovary syndrome (PCOS), the commonest endocrine disorder in women, is characterized by an altered steroid milieu and is associated with insulin resistance and type 2 diabetes mellitus (T2DM). Phosphoprotein enriched in diabetes gene product (Ped/pea-15) regulates glucose metabolism and is increased in T2DM. Our novel data indicate that Ped/pea-15 mRNA expression and protein levels are significantly increased in omental adipose tissue (AT) from PCOS women compared to matched controls (p < 0.01); Ped/pea-15 levels in subcutaneous AT were not significantly different. Furthermore, Ped/pea-15 mRNA expression and protein levels were higher in omental compared to subcutaneous AT in PCOS subjects (p < 0.01); however, in control subjects, this was not significant. Glucose was predictive of omental AT Ped/pea-15 mRNA expression (p = 0.045). Importantly, glucose and insulin increased whereas metformin significantly decreased Ped/pea-15 levels in human omental AT explants. Our findings should serve to promote further research on Ped/pea-15 biology.

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 (Erk1/2) 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 Erk1/2 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 Erk1/2 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.

Obesity has reached pandemic proportions and is associated with serious cardiometabolic sequealae 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.

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.

To study the diurnal variation and the effect of insulin on adiponectin multimers and nuclear factor-kappaB (NF-κB) activity in human endothelial cells.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 (P0.05, P0.01). There were no significant changes to MMW and LMW adiponectin levels (P0.05).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.

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.Circulating ASAA (ELISA), subcutaneous and omental AT ASAA mRNA (RT-PCR) and protein (western blotting) were significantly higher in PCOS women (P0.05). In AT explants, glucose significantly increased ASAA production and secretion (P0.05, P0.01). Furthermore, ASAA production (THP-1 macrophages) was significantly greater by sera from PCOS women compared to controls (P0.01). ASAA protein production was significantly decreased by sera from PCOS women following 6 months of metformin treatment (P0.05). After 6 months of metformin treatment, there was a significant decrease in circulating ASAA (P0.05). Importantly, changes in intima media thickness were predictive of changes in circulating ASAA (P=0.034).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.

Aims Polycystic ovary syndrome (PCOS) is associated with insulin resistance (IR), obesity, and cardiovascular complications. Thrombospondin-1 (TSP-1) is a novel antiangiogenic adipokine highly expressed in obese insulin-resistant subjects. We sought to assess TSP-1 levels in adipose tissue (AT) from PCOS women and matched controls. The effects of metformin treatment on circulating TSP-1 levels in PCOS subjects, the effects of serum from normal and PCOS women on in vitro migration and angiogenesis before and after metformin treatment, and ex vivo regulation of AT TSP-1 by D-glucose were also studied. Methods and results Serum TSP-1 (ELISA), subcutaneous and omental AT TSP-1 mRNA (reverse transcriptase–polymerase chain reaction), and protein (western blotting) were significantly lower in PCOS women ( P < 0.05). Corresponding plasminogen activator inhibitor-1 (PAI-1) and PAI-1 activity were significantly higher ( P < 0.01). After 6 months of metformin treatment, there was a significant increase in serum TSP-1 ( P < 0.05) and a corresponding decrease in PAI-1 and PAI-1 activity ( P < 0.01). In vitro migration and angiogenesis were significantly increased in serum from PCOS women ( P < 0.01); these effects were significantly attenuated by metformin treatment ( P < 0.01) through the regulation of TSP-1 levels via nuclear factor-κB (NF-κB), extracellular regulated-signal kinase 1/2 (Erk1/2) and Erk5 pathways. Importantly, changes in the intima media thickness were predictive of changes in serum TSP-1 ( P = 0.049). In AT explants, glucose significantly decreased TSP-1 protein production and secretion into conditioned media (ELISA) ( P < 0.05, P < 0.001). Conclusion TSP-1 levels are lower in PCOS women. Metformin treatment increases serum TSP-1 in these women. Our findings provide novel insights into the relationship between obesity, IR, and angiogenesis.

OBJECTIVE—Lipocalin-2, a novel adipokine, has been shown to be elevated in obese, insulin-resistant, and diabetic subjects. We therefore sought to study the ex vivo and in vivo effects of insulin on lipocalin-2 levels in humans. RESEARCH DESIGN AND METHODS—We investigated the in vivo effects of insulin (hyperinsulinemia) on circulating lipocalin-2 levels by enzyme-linked immunosorbent assay via a prolonged insulin-glucose infusion. The ex vivo effect of insulin on adipose tissue lipocalin-2 protein production and secretion into conditioned media was assessed by Western blotting and enzyme-linked immunosorbent assay, respectively. RESULTS—Hyperinsulinemic induction in human subjects significantly increased circulating lipocalin-2 levels (P < 0.01). Also, in omental adipose tissue explants, insulin caused a significant dose-dependent increase in lipocalin-2 protein production and secretion into conditioned media (P < 0.05, P < 0.01, respectively); these effects were negated by both phosphatidylinositol 3-kinase and mitogen-activated protein kinase kinase inhibitors. CONCLUSIONS—Lipocalin-2 is upregulated by insulin via phosphatidylinositol 3-kinase and mitogen-activated protein kinase signaling pathways.

OBJECTIVE—Polycystic ovary syndrome (PCOS) is associated with insulin resistance and obesity. Vaspin (visceral adipose tissue–derived serine protease inhibitor) levels increase with hyperinsulinemia and obesity. Currently, no data exists on vaspin in PCOS women. We therefore assessed mRNA and protein levels of vaspin, including circulating vaspin, from subcutaneous and omental adipose tissue of PCOS women and matched control subjects. Ex vivo regulation of adipose tissue vaspin and the effects of metformin treatment on circulating vaspin levels in PCOS subjects were also studied. RESEARCH DESIGN AND METHODS—Real-time RT-PCR and Western blotting were used to assess mRNA and protein expression of vaspin. Serum vaspin was quantified by enzyme-linked immunosorbent assay. The effects of d-glucose, insulin, and gonadal and adrenal steroids on adipose tissue vaspin were analyzed ex vivo. RESULTS—There were significantly higher levels of circulating vaspin (P < 0.05), vaspin mRNA (P < 0.05), and protein (P < 0.05) in omental adipose tissue of PCOS women. Interestingly, in omental adipose tissue explants, glucose significantly increased vaspin protein levels and secretion into conditioned media (P < 0.001). Also, after 6 months of metformin treatment, there was a significant decrease in serum vaspin levels in PCOS women (P < 0.001). Furthermore, multivariate regression analysis revealed that following metformin therapy, changes in circulating glucose levels were predictive of changes in serum vaspin levels (P = 0.014). CONCLUSIONS—We report, for the first time, elevated serum and omental adipose tissue levels of vaspin in overweight PCOS women and ex vivo regulation of vaspin, predominantly by glucose. More importantly, metformin treatment decreases serum vaspin levels, a novel observation.

Visfatin is elevated in obesity and type 2 diabetes and is thought to be an inflammatory mediator within atherosclerotic lesions and to induce gelatinase activity. We investigated the activation of nuclear factor-kappaB (NF-kappaB), a well-known proinflammatory transcription factor, by visfatin in endothelial cells.Human endothelial cells were transfected with pNF-kappaB-Luc plasmid. Using quantitative PCR, Western blot analysis, and gelatin zymography, we studied NF-kappaB signaling in gelatinase-mediated vascular inflammation by visfatin using the NF-kappaB inhibitor BAY 11-7085.Visfatin significantly increased NF-kappaB transcriptional activity (P0.001). We also found a significant inhibition of tumor necrosis factor-alpha (TNF-alpha)-induced NF-kappaB activity by visfatin (P0.001). Furthermore, the NF-kappaB inhibitor significantly negated visfatin-induced matrix metalloproteinase (MMP)-2/9 mRNA expression, protein levels, and gelatinolytic activity (P0.001).Visfatin-induced NF-kappaB signaling in human endothelial cells affects the activation of gelatinases MMP-2 and -9, suggesting an important role of visfatin in the pathogenesis of vascular inflammation in obesity and type 2 diabetes.

Polycystic ovary syndrome (PCOS) is associated with insulin resistance and obesity. Recent studies have shown that plasma omentin-1 levels decrease with obesity. Currently, no data exist on the relative expression and regulation of omentin-1 in adipose tissue of women with PCOS. The objective of this study was to assess mRNA and protein levels of omentin-1, including circulating omentin-1, in omental adipose tissue of women with PCOS and matched control subjects. Ex vivo and in vivo regulation of adipose tissue omentin-1 was also studied.Real-time RT-PCR and Western blotting were used to assess mRNA and protein expression of omentin-1. Plasma omentin-1 was measured by enzyme-linked immunosorbent assay. The effects of d-glucose, insulin, and gonadal and adrenal steroids on adipose tissue omentin-1 were analyzed ex vivo. The in vivo effects of insulin (hyperinsulinemia) on omentin-1 levels were also assessed by a prolonged insulin-glucose infusion.In addition to decreased plasma omentin-1 levels in women with PCOS (P0.05), compared with control subjects, there was significantly lower levels of omentin-1 mRNA (P0.01) and protein (P0.05) in omental adipose tissue of women with PCOS (P0.01). Furthermore, in omental adipose tissue explants, insulin and glucose significantly dose-dependently decreased omentin-1 mRNA expression, protein levels, and secretion into conditioned media (P0.05, P0.01). Also, hyperinsulinemic induction in healthy subjects significantly reduced plasma omentin-1 levels (P0.01).Our novel findings reveal that omentin-1 is downregulated by insulin and glucose. These may, in part, explain the decreased omentin-1 levels observed in our overweight women with PCOS.

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 (βKlotho) 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-βKlotho components. Cardiac-FGF21 expression and secretion were increased in response to global ischemia. In contrast βKlotho 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.

Multiple myeloma is a clonal lymphoproliferative disorder characterised by the proliferation of plasma cells in the bone marrow. Inspite of good initial response, it is associated with universal relapse. We hypothesise this is due to sanctuary provided to myeloma cells by the endothelium. Matrix metalloproteinases (MMPs) are shown play a role in cell growth, invasion, angiogenesis, metastasis and bone degradation. We show here the protection offered by endothelial cells to human myeloma cell lines in in-vitro co-culture with upregulation of MMP-2 & 9 and the role of GM6001 MMP inhibitor (Ilomastat) in overcoming this protection. Human myeloma cell lines (H929, RPMI 8226, U266 & JJN3) with or without endothelial cells (human umbilical vein endothelial cells and EaHy 926 cell line) in-vitro co-culture were treated with melphalan, dexamethasone, arsenic trioxide and Ilomastat. Cytotoxicity/proliferation were assessed by the alamarBlue™ assay (Serotec) and validated by Annexin V-FITC apoptosis detection Kit (Calbiochem) and BrDU proliferation assay (BD Pharmingen™). Gelatin Zymography was used to demonstrate activity of MMP-2 & 9 in the supernatant. MMP-2 and 9 mRNA expression was quantified by Real Time Quantitative PCR (ROCHE). Co-culture of human myeloma cell lines with endothelial cells lead to increase in the proliferation of myeloma cell lines and also protected them from the cytotoxicity of chemotherapeutic agents. MMP-2 & 9 activity was upregulated by the co-culture. MMP-2 mRNA expression in human myeloma cell lines increased following 4 hr co-culture. Treatments with Ilomastat lead to the suppression of proliferation in co-culture in a dose dependent manner, associated with a reduction of MMP-2 and 9 activity. Our study shows endothelial cells offer protection to human myeloma cell lines in the presence of cytotoxic agents. This may result in the sanctuary of myeloma cells in bone marrow leading to ultimate relapse of disease. Our study also demonstrates the upregulation of MMP-2 and 9 by co-culture and increased cytotoxicity achieved by the inhibition of MMPs. Further studies are needed to determine the exact role of MMPs in myeloma biology as MMP inhibition may be an interesting therapeutic target and help in averting relapse in multiple myeloma.