Sterol Regulatory Binding Protein Research Articles

SREBP signaling is essential for effective B cell responses.

Our previous study using systems vaccinology identified an association between the sterol regulatory binding protein (SREBP) pathway and humoral immune response to vaccination in humans. To investigate the role of SREBP signaling in modulating immune responses, we generated mice with B cell- or CD11c+ antigen-presenting cell (APC)-specific deletion of SCAP, an essential regulator of SREBP signaling. Ablation of SCAP in CD11c+ APCs had no effect on immune responses. In contrast, SREBP signaling in B cells was critical for antibody responses, as well as the generation of germinal centers,memory B cells and bone marrow plasma cells. SREBP signaling was required for metabolic reprogramming in activated B cells. Upon mitogen stimulation, SCAP-deficient B cells could not proliferate and had decreased lipid rafts. Deletion of SCAP in germinal center B cells using AID-Cre decreased lipid raft content and cell cycle progression. These studies provide mechanistic insights coupling sterol metabolism with the quality and longevity of humoral immunity.

Interleukin-1 Induces the Release of Lubricating Phospholipids from Human Osteoarthritic Fibroblast-like Synoviocytes.

(1) Background: Synovial fluid (SF) from knee joints with osteoarthritis (OA) has increased levels of phospholipids (PL). We have reported earlier that TGF-ß and IGF-1 stimulate fibroblast-like synoviocytes (FLS) to synthesize increased amounts of PLs. The current study examined whether IL-1ß induces the release of PLs in FLS and the underlying mechanism. (2) Methods: Cultured human OA FLS were treated with IL-1ß alone and with pathway inhibitors or with synthetic liver X receptor (LXR) agonists. Cholesterol hydroxylases, ABC transporters, apolipoproteins (APO), LXR, sterol regulatory binding proteins (SREBPs), and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) were analyzed by RT-PCR, Western blot, and ELISA. The release of radiolabeled PLs from FLS was determined, and statistical analysis was performed using R (N = 5–9). (3) Results: Like synthetic LXR agonists, IL-1ß induced a 1.4-fold greater release of PLs from FLS. Simultaneously, IL-1ß upregulated the level of the PL transporter ABCA1 and of cholesterol hydroxylases CH25H and CYP7B1. IL-1ß and T0901317 stimulated the expression of SREBP1c, whereas only T0901317 enhanced SREBP2, HMGCR, APOE, LXRα, and ABCG1 additionally. (4) Conclusions: IL-1ß partially controls PL levels in OA-SF by affecting the release of PLs from FLS. Our data show that IL-1ß upregulates cholesterol hydroxylases and thus the formation of oxysterols, which, as natural agonists of LXR, increase the level of active ABCA1, in turn enhancing the release of PLs.

Histone Deacetylase 1 Reduces Lipogenesis by Suppressing SREBP1 Transcription in Human Sebocyte Cell Line SZ95.

Proper regulation of sebum production is important for maintaining skin homeostasis in humans. However, little is known about the role of epigenetic regulation in sebocyte lipogenesis. We investigated histone acetylation changes and their role in key lipogenic gene regulation during sebocyte lipogenesis using the human sebaceous gland cell line SZ95. Sebocyte lipogenesis is associated with a significant increase in histone acetylation. Treatment with anacardic acid (AA), a p300 histone acetyltransferase inhibitor, significantly decreased the lipid droplet number and the expression of key lipogenic genes, including sterol regulatory-binding protein 1 (SREBP1), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC). In contrast, treatment with trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor, increased the expression of these genes. Global HDAC enzyme activity was decreased, and HDAC1 and HDAC2 expression was downregulated during sebaceous lipogenesis. Interestingly, HDAC1 knockdown increased lipogenesis through SREBP1 induction, whereas HDAC1 overexpression decreased lipogenesis and significantly suppressed SREBP1 promoter activity. HDAC1 and SREBP1 levels were inversely correlated in human skin sebaceous glands as demonstrated in immunofluorescence images. In conclusion, HDAC1 plays a critical role in reducing SREBP1 transcription, leading to decreased sebaceous lipogenesis. Therefore, HDAC1 activation could be an effective therapeutic strategy for skin diseases related to excessive sebum production.

High Fiber and Beta Carotene from Sweet Potatoes and Pumpkin Improve Insulin Resistance by Inhibition of Sterol Regulatory Binding Protein 1c in Liver of Hypertriglyceridemic Rats

BACKGROUND: High sterol regulatory binding protein 1c (SREBP-1c) gene expression increases triglyceride synthesis, which induces insulin resistance. Short-chain fatty acids (SCFAs) from fiber fermentation and beta carotene may inhibit SREBP-1c gene expression.
 AIM: The aim of this study was to evaluate the high fiber and beta carotene diet on improving insulin resistance in hypertriglyceridemia rats.
 METHODS: A total of 25 Wistar male rats were divided into five groups: (1) Normal control (NC); (2) hypertriglyceridemia control (HC); (3) hypertriglyceridemia rats with treatment 1 (HT1); (4) hypertriglyceridemia rats with treatment 2 (HT2); and (5) hypertriglyceridemia rats with treatment 1 (HT3). The HT1, HT2, and HT3 received fiber 1.0 g; 2.0 g; and 3.1 g and beta carotene 725.7 μg; 1451.5 μg; and 2177.2 μg per day, respectively, for 6 weeks. The HC received high fat and fructose diet and the NC received a standard diet. The levels of triglyceride were analyzed using the colorimetric method before and after treatment. At the end of the study, the expression of SREBP-1c was identified by a quantitative polymerase chain reaction.
 RESULTS: High fat and fructose diet increased the levels of triglyceride (36.53 ± 1.27 vs. 119.79 ± 7.73), but high fiber and beta carotene diet can reduce triglyceride levels in HT1 (94.58 ± 4.53 vs. 77.70 ± 7.97); HT2 (115.58 ± 4.76 vs. 66.90 ± 3.11); and HT3 (103.87 ± 7.47 vs. 62.06 ± 4.45). The decreased triglyceride levels were related to low SREBP-1c gene expression, especially in the liver. Low SREBP-1c gene expression was correlated with homeostatic model assessment of insulin resistance index with r = 0.414; p < 0.05 in the liver and r = 0.158; p > 0.05 in white adipose tissues.
 CONCLUSION: High fiber and beta carotene diet can improve insulin resistance through inhibition of SREBP-1c gene expression.

Mass spectrometry–based lipidomics of oral squamous cell carcinoma tissue reveals aberrant cholesterol and glycerophospholipid metabolism — A Pilot study

Lipid metabolic reprogramming is one hallmark of cancer. Lipid metabolism is regulated by numerous enzymes, many of which are targeted by several drugs on the market. We aimed to characterize the lipid alterations in oral squamous cell carcinoma (OSCC) as a basis for understanding its lipid metabolism, thus identifying potential therapeutic targets. We compared lipid species, classes, and glycerophospholipid (GPL) fatty acid species between paired tumor tissue and healthy oral tongue mucosa samples from 10 OSCC patients using a QExactive mass spectrometer. After filtering the 1370 lipid species identified, we analyzed 349 species: 71 were significantly increased in OSCC. The GPL metabolism pathway was most represented by the lipids differing in OSCC (P = .005). Cholesterol and the GPLs phosphatidylcholines, phosphatidylethanolamines, and phosphatidylinositols were most significantly increased in OSCC tissue (FC 1.8, 2.0, 2.1, and 2.3 and, P = .003, P = .005, P = .002, P = .007). In conclusion, we have demonstrated a shift in the lipid metabolism in these OSCC samples by characterizing the detailed landscape. Predominantly, cholesterol and GPL metabolism were altered, suggesting that interactions with sterol regulatory binding proteins may be involved. The FA composition changes of the GPLs suggest increased de novo lipogenesis.

Disruption of cholesterol metabolism via sigma-2 ligands induces cell death in pancreatic cancer

Presenter: Rony Takchi MD | Washington University, St. Louis Background: The malignant transformation of pancreatic ductal adenocarcinoma (PDAC) is accompanied by alteration of the metabolism to adapt to the new hypoxic and nutrient-deprived micro-environment. Recent studies have shown that PDAC is highly dependent on cholesterol import. Consequently, tumors with a high LDL-receptor (LDL-R) expression phenotype are more aggressive, which is linked with worse patient survival. Like other proliferating tumors, PDAC is characterized by overexpression of the sigma-2 receptor, which is involved in enhanced LDL-R activity and the regulation of cholesterol export from the lysosomes in an NPC1-dependent manner. We thus hypothesized that sigma-2 ligands may facilitate pancreatic cancer cell death via cholesterol trapping in the lysosomes through disruption of the NPC1-mediated export mechanism. Methods: The sigma-2 ligands tested are the azabicyclononane analogs SW43, SW96, SV95, and the benzamide analog, ISO-1. To determine the kinetics and the cellular localization properties of a representative member of the sigma-2 ligand family, SW43 was chemically linked to the fluorophore 4-Chloro-7-nitro-1,2,3-benzoxadiazole (NBD-Cl; SW120). To study the impact on cellular cholesterol trafficking upon sigma-2 ligand treatment, cells were stained with Filipin and analyzed via confocal microscopy. Protein abundance of key players involved in intracellular cholesterol processing/trafficking was determined using state-of-the-art WES technology employing the following antibodies: Sterol-regulatory binding protein 2 (SREBP2), LDL-R, Niemann-Pick C1 protein (NPC1). Cell viability was determined using IncuCyte live-cell analysis system. In order to study the predicted synergism between cholesterol sequestration and blocking of de novo cholesterol synthesis, PDAC cells were treated with sigma-2 ligands in combination with simvastatin, which inhibits the rate-limiting enzyme in cholesterol synthesis 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCoAr). Drug combination effects (synergy) were determined using CompuSyn software. Results: Utilizing three different human pancreatic cancer cell lines (AsPC1, HPAC, and MiaPaca-2), fluorescently labeled sigma-2 ligand SW120 was shown to be rapidly taken up into the lysosomal compartment within minutes. This rapid uptake mechanism was associated with a moderate cytotoxicity profile of the sigma-2 ligands SW43 and SW96. Of note, the sigma-2 ligand-mediated cytotoxicity correlated with a rapid cholesterol sequestration phenotype in the lysosomes. In contrast, treatment with two other, high-affinity sigma-2 ligands SV95 and ISO1, was not associated with cytotoxicity and did not lead to cholesterol sequestration. Since trapping of cholesterol in the lysosomes renders it unusable for the cell, analogous to the lysosomal storage disease Niemann-Pick type C, actuation of the sterol sensing machinery was predicted. And indeed, shortly (time) after exposure to SW43 or SW96, the cholesterol sensor released SREBP-2 which in turn was activated and induced production of its downstream targets, LDL-R and NPC1. Moreover, the combination of cholesterol sequestration (SW43) and blocking of de novo cholesterol production (simvastatin), demonstrated a synergistic drug activity profile. Conclusion: We identified a cholesterol trapping phenotype as an early event of sigma-2 ligand-mediated cytotoxicity. Targeting both LDL-R-mediated lysosomal cholesterol trapping with sigma-2 ligands in combination with blockage of de-novo cholesterol synthesis lead to synergistic cancer cell death and thus represents an intriguing novel treatment concept for PDAC.

Lyophilized Maqui (Aristotelia chilensis) Berry Induces Browning in the Subcutaneous White Adipose Tissue and Ameliorates the Insulin Resistance in High Fat Diet-Induced Obese Mice.

Maqui (Aristotelia Chilensis) berry features a unique profile of anthocyanidins that includes high amounts of delphinidin-3-O-sambubioside-5-O-glucoside and delphinidin-3-O-sambubioside and has shown positive effects on fasting glucose and insulin levels in humans and murine models of type 2 diabetes and obesity. The molecular mechanisms underlying the impact of maqui on the onset and development of the obese phenotype and insulin resistance was investigated in high fat diet-induced obese mice supplemented with a lyophilized maqui berry. Maqui-dietary supplemented animals showed better insulin response and decreased weight gain but also a differential expression of genes involved in de novo lipogenesis, fatty acid oxidation, multilocular lipid droplet formation and thermogenesis in subcutaneous white adipose tissue (scWAT). These changes correlated with an increased expression of the carbohydrate response element binding protein b (Chrebpb), the sterol regulatory binding protein 1c (Srebp1c) and Cellular repressor of adenovirus early region 1A–stimulated genes 1 (Creg1) and an improvement in the fibroblast growth factor 21 (FGF21) signaling. Our evidence suggests that maqui dietary supplementation activates the induction of fuel storage and thermogenesis characteristic of a brown-like phenotype in scWAT and counteracts the unhealthy metabolic impact of an HFD. This induction constitutes a putative strategy to prevent/treat diet-induced obesity and its associated comorbidities.

Effect of brimonidine, an α2 adrenergic agonist, on human meibomian gland epithelial cells

We recently discovered that the anti-glaucoma pharmaceuticals timolol, a β adrenergic antagonist, and pilocarpine, a cholinergic compound, negatively influence the morphology, proliferative capacity and survival of human meibomian gland epithelial cells (HMGECs). We hypothesize that another class of anti-glaucoma drugs, the α2 adrenergic agonists, also acts directly on HMGECs to affect their structure and function. We tested this hypothesis. Immortalized (i) HMGECs were cultured with brimonidine, as well as clonidine (α2 agonist), phenylephrine (α1 agonist), RX821002 (inverse α2 agonist) and MK912 (neutral α2 agonist) for up to 7 days. Cells were counted with a hemocytometer, and evaluated for morphology, signaling pathway activity, protein biomarker expression, and the accumulation of neutral lipids, phospholipids and lysosomes. Our findings demonstrate that brimondine treatment induces a dose-dependent decrease in Akt signaling and proliferation of iHMGECs. In contrast, brimonidine also promotes a dose-dependent differentiation of iHMGECs, including an increase in neutral lipid, phospholipid and lysosome levels. These effects were paralleled by an inhibition of p38 signaling, and duplicated by cellular exposure to clonidine, but not phenylephrine. Brimonidine also enhanced the cellular content of sterol regulatory binding protein-1, a master regulator of lipid synthesis. Of particular interest, the putative α2 antagonists, RX821002 and MK912, did not interfere with brimonidine action, but rather stimulated IHMGEC differentiation. Our results support our hypothesis and demonstrate that α2 adrenergic agonists act directly on iHMGECs. However, these compounds do not elicit an overall negative effect. Rather, the α2 agonists promote the differentiation of iHMGECs.

Cocaine and HIV-1 Tat disrupt cholesterol homeostasis in astrocytes: Implications for HIV-associated neurocognitive disorders in cocaine user patients.

Cholesterol synthesis and clearance by astrocytes are tightly regulated to maintain constant levels within the brain. In this context, liver X receptors (LXRs) are the master regulators of cholesterol homeostasis in the central nervous system (CNS). Increasing levels of cholesterol in astrocytes trigger LXR activation leading to the transcription of target genes involved in cholesterol trafficking and efflux, including apolipoprotein E, cytochrome P450 enzymes, sterol regulatory binding protein, and several ATP-binding cassette transporter proteins. The disturbance of LXR signaling in the brain can lead to significant dysfunctions in cholesterol homeostasis, and disruptions in this pathway have been implicated in numerous neurological diseases including Alzheimer's disease and Huntington's disease. HIV infection of the CNS in combination with cocaine use is associated with astrocyte and neuronal energy deficit and damage. We propose that dysregulation in CNS cholesterol metabolism may be involved in the progression of HIV-associated neurocognitive disorders (HAND) and in cocaine-mediated neurocognitive impairments. We hypothesize that exposure of astrocytes to cocaine and the HIV protein Tat will disrupt LXR signaling. Alterations in these pathways will in turn, affect cholesterol bioavailability for neurons. Our data show that exposure of astrocytes to cocaine and HIV-Tat significantly decreases LXRβ levels, downstream signaling and bioavailability of cholesterol. Taken together, these data uncover novel alterations in a bioenergetic pathway in astrocytes exposed to cocaine and the HIV protein Tat. Results from these studies point to a new pathway in the CNS that may contribute to HAND in HIV+ cocaine user individuals.

Elevated sterol regulatory elementary binding protein 1 and GluA2 levels in the hippocampal nuclear fraction of Genetic Absence Epilepsy Rats from Strasbourg

Studies in animal models and human tissues show that nuclear translocation of sterol regulatory element binding protein 1 (SREBP1) and glutamate A2 subunit (GluA2) of cell-surface AMPA receptor (AMPAR) trigger neuronal excitotoxicity-induced apoptosis in stroke. However, it is not known whether a similar type of underlying pathophysiology occurs in absence epilepsy. To explore this issue, we examined the levels of mature SREBP1, GluA2, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), p53, and activated to total caspase 3 ratio in nuclear fractions (NF) of hippocampal homogenate from 8 to 10 week old male Genetic Absence Epilepsy Rats from Strasbourg (GAERS) and non-epileptic control (NEC) strains. Mature SREBP1 and GluA2 levels were elevated approximately two-fold in NFs of GAERS hippocampal homogenates compared to NEC animals. Significant increases in GAPDH (∼15-fold) and total caspase 3 (∼10-fold) levels were also found in NFs of GAERS hippocampal homogenates in comparison to the non-epileptic strain. Data from the current study suggest that absence epilepsy in GAERS is associated with nuclear translocation of mature SREBP1, GluA2 subunit of AMPARs, and recruitment of pro-cell death signaling proteins such as GAPDH and caspase 3. These changes may contribute to hippocampal neuronal/glial cell death in GAERS. Therefore, inhibiting the nuclear accumulation of mature SREBP1 and GluA2 translocation may reduce the pathophysiology of absence epilepsy.

Metabolic Phenotypes of Response to Vaccination in Humans

Herpes zoster (shingles) causes significant morbidity in immune compromised hosts and older adults. Whereas a vaccine is available for prevention of shingles, its efficacy declines with age. To help to understand the mechanisms driving vaccinal responses, we constructed a multiscale, multifactorial response network (MMRN) of immunity in healthy young and older adults immunized with the live attenuated shingles vaccine Zostavax. Vaccination induces robust antigen-specific antibody, plasmablasts, and CD4+ Tcells yet limited CD8+ Tcell and antiviral responses. The MMRN reveals striking associations between orthogonal datasets, such as transcriptomic and metabolomics signatures, cell populations, and cytokine levels, and identifies immune and metabolic correlates of vaccine immunity. Networks associated with inositol phosphate, glycerophospholipids, and sterol metabolism are tightly coupled with immunity. Critically, the sterol regulatory binding protein 1 and its targets are key integrators of antibody and T follicular cell responses. Our approach is broadly applicable to study human immunity and can help to identify predictors of efficacy as well as mechanisms controlling immunity to vaccination.

Promiscuous activity of the LXR antagonist GSK2033 in a mouse model of fatty liver disease

The liver X receptor (LXR) functions as a receptor for oxysterols and plays a critical role in the regulation of glucose and lipid metabolism. We recently described a synthetic LXR inverse agonist that displayed efficacy in treatment of hepatic steatosis in a mouse model of non-alcoholic fatty liver disease (NAFLD). This compound, SR9238, was designed to display liver specificity so as to avoid potential detrimental effects on reverse cholesterol transport in peripheral tissues. Here, we examined the effects of a LXR antagonist/inverse agonist, GSK2033, which displays systemic exposure. Although GSK2033 performed as expected in cell-based models as a LXR inverse agonist, it displayed unexpected activity in the mouse NAFLD model. The expression of lipogenic enzyme genes such as fatty acid synthase and sterol regulatory binding protein 1c were induced rather than suppressed and no effect on hepatic steatosis was found. Further characterization of the specificity of GSK2033 revealed that it displayed a significant degree of promiscuity, targeting a number of other nuclear receptors that could clearly alter hepatic gene expression.

Anti-adipogenic effect of oat hull extract containing tricin on 3T3-L1 adipocytes

Oat hull ethyl acetate extract (50μg/μL) significantly inhibited triglyceride accumulation in 3T3-L1 adipocytes without causing cytotoxicity. The major active compound in the extract was isolated and identified as 5,7,4′-trihydroxy-3′,5′-dimethoxyflavone, tricin by mass spectrometry and 1H and 13C NMR analyses. The tricin content in oat hull was approximately 18mg/kg dry weight, and tricin constituted 9.6% of the total phenolic compounds in oat hull extract. The treatment of 3T3-L1 cells either with extract or purified tricin resulted in decreased lipid accumulation. The extract significantly decreased the activity of glycerol-3-phosphate dyhydrogenase, a marker of adipocyte differentiation in a dose dependent manner. The expression of major transcription factors, such as peroxisome proliferator-activated receptor (PPAR)-γ, CCATT/enhancer binding protein-α (CEBP/α), sterol regulatory binding protein 1 (SREBP1) and fatty acid synthase (FAS) was also significantly suppressed by the extract. When commercial purified tricin was added to 3T3-L1 cells the expression of all transcription factors were significantly decreased as low as 1.5μg/μL treatment. These results suggest that oat hull extract containing tricin possesses anti-adipogeneic effect.

Regulation of the fatty acid synthase promoter by liver X receptor α through direct and indirect mechanisms in goat mammary epithelial cells.

Fatty acid synthase (FASN) is a central enzyme of milk fat synthesis in the ruminant mammary gland. However, the mechanisms regulating goat FASN transcription remain elusive. The objective of this study was to investigate the mechanisms by which liver X receptor α (LXRα) regulates the FASN promoter in goat mammary epithelial cells (GMECs). In this study, T0901317 (T09), an agonist for LXRα, significantly enhanced the mRNA expression and promoter activity of FASN. Cloning of the dairy goat FASN promoter revealed the presence of one LXR response element (LXRE) and two sterol regulatory elements (SREs). Deletion or mutation of the FASN promoter LXRE reduced, but did not eliminate the transcriptional response of FASN to T09. While the LXRE and the SREs were both disrupted, basal transcription was severely reduced and there was no response to T09 treatment. This suggested that a complete response required one LXRE and two SREs. Knockdown of LXRα by siRNA did not alter the basal or T09-induced transcriptional activity of FASN. However, when sterol regulatory binding protein 1 (SREBP1) was knocked down, T09 significantly increased FASN transcription by wild-type GMECs, but had no effect on cells with LXRE-mutant promoters. The results suggested that LXR regulates FASN promoter activity through direct interaction with the LXRE as well as through increasing SREBP1 abundance. The present study provides insight into the transcriptional regulatory mechanisms controlling de novo fatty acid synthesis in GMECs.

Lipolytic and antiadipogenic effects of (3,3-dimethylallyl) halfordinol on 3T3-L1 adipocytes and high fat and fructose diet induced obese C57/BL6J mice

Aegle marmelos Correa., (Rutaceae) is a medium sized tree distributed in South East Asia and used traditionally for the management of obestiy and diabetes. In this study the lipolytic and antiadipogenic effects of (3,3-dimethylallyl) halfordinol (Hfn) isolated from leaves of A. marmelos have been investigated. Intracellular lipid accumulation was measured by oil red O staining and glycerol secretion. The expression of genes related to adipocyte differentiation was analyzed by reverse transcriptase–polymerase chain reaction (RT-PCR). Hfn decreased intracellular triglyceride accumulation and increased glycerol release in a dose dependent manner (5–20μg/ml) in differentiated 3T3-L1 adipocytes. In high fat diet fed C57/BL 6J mice, treatment with Hfn for four weeks reduced plasma glucose, insulin and triglyceride levels and showed a significant reduction in total adipose tissue mass by 37.85% and visceral adipose tissue mass by 62.99% at 50mg/kg b.w. concentration. RT-PCR analyses indicated that Hfn decreased the expression of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT enhancer binding protein α (CEBPα) and increased the expression of sterol regulatory enzyme binding protein (SREBP-1c), peroxisome proliferator-activated receptor α (PPARα), Adiponectin and Glucose transporter protein 4 (GLUT4) compared to the high fat diet group. These results suggested that Hfn decreased adipocyte differentiation and stimulated lipolysis of adipocytes. This study justifies the folklore medicinal uses and claims about the therapeutic values of this plant for the management of insulin resistance and obesity.

Effects of laccase-catalyzed rutin polymer fraction on adipogenesis inhibition in 3T3-L1 adipocytes

Rutin was enzymatically polymerized by laccase and the rutin polymer fraction (RPF) was collected by ultrafiltration with a molecular cut off of 3kDa. The RPF contained a range of oligomer size varying from hexamer (m/z 3650) to octamer (m/z 4866). The Fourier transform infrared spectrum indicated that various linkages such as hydrogen bonds (OH), aromatic groups (CC), and ether bonds (CO) were involved in rutin polymer formation. RPF more effectively suppressed triglyceride accumulation compared to the rutin monomer in 3T3-L1 adipocytes at all tested concentrations (p<0.05). The anti-adipogenic effect of RPF was mediated by down-regulation of the expression of adipogenic transcriptional factors including peroxisome proliferator-activated receptor (PPARγ), CCATT/enhancer binding protein (C/EBPα), sterol regulatory binding protein (SREBP1C) and fatty acid synthase (FAS) while up-regulating lipolysis and adiponectin expression in 3T3-L1 adipocytes. These results suggest that RPF has a potential protective effect in the development of obesity and that enzyme-catalyzed polymerization could be useful in improving flavonoids bioactivity.

Stearoyl-CoA desaturase and sterol regulatory binding protein 1 markers: Effect on the volatile profile of dry-cured Parma, San Daniele and Toscano hams as detected by PTR-ToF-MS

The effect of the stearoyl-CoA desaturase (SCD) and sterol regulatory binding transcription factor 1 (SREBF1) polymorphisms on the volatile compound profile of dry-cured hams from Italian protected denomination of origin (Prosciutto di Parma, Prosciutto di San Daniele and Prosciutto Toscano) was investigated by proton transfer reaction time-of-flight mass spectrometry. The SCD polymorphism had a strong effect on the volatile compound profile in Prosciutto di San Daniele, but moderate in Prosciutto di Parma and very scarce in Prosciutto Toscano. Moreover, the effect of the SREBF1 polymorphism was also strong in Prosciutto di San Daniele and moderate in Prosciutto di Parma and Prosciutto Toscano. The main effect of both markers was found in the peaks tentatively identified as volatile compounds from the unsaturated fatty acids oxidation, with higher concentrations in dry-cured hams with SCD TC and SREBF1 AG genotypes, as they seem to increase the concentration of the fatty acids precursor of those compounds.

Effect of ambrex (a herbal formulation) on oxidative stress in hyperlipidemic rats and differentiation of 3T3-L1 preadipocytes.

Background:Ambrex is a polyherbal formulation which consists of Withania somnifera, Orchis mascula, Cycas circirnalis, Shorea robusta with amber.Objective:The present study was designed to explore the potential effects of ambrex on the antioxidant status in high fat diet fed rats and to investigate the possible mechanisms focusing on the gene expression involved in adipogenesis and inflammation in 3T3-L1 cell line.Materials and Methods:Male Wistar rats were divided into four groups (n = 6); Group A received normal diet, Group B received high fat diet for 30 days, Group C and D received high fat diet for 30 days and treated with ambrex (40 mg/kg b.w) and atorvastatin (10 mg/kg b.w) for successive 15 days respectively. This study also assesses the effect of ambrex on adipogenesis in 3T3-L1 adipocytes.Results:The serum total cholesterol and triglycerides were significantly decreased in ambrex treated hyperlipidemic animals when compared to untreated animals. The activities of catalase, superoxide dismutase and reduced glutathione were significantly augmented in the serum, liver, and heart of hyperlipidemic rats treated with ambrex when compared to control. Ambrex treated rats had significant reductions in malondiadehyde levels in the serum, liver and heart compared to untreated rats. In addition, we observed that treatment with ambrex resulted in a major inhibition of pre-adipocyte differentiation of 3T3-L1 cells in vitro by suppression of peroxisome proliferator activated receptor gamma, sterol regulatory binding proteins, tumor necrosis factor-α, inducible nitricoxide synthase, leptin, and upregulation of thioredoxin 1 (TRX1) and TRX2 mRNA expression.Conclusion:Therefore, ambrex may be a potential drug for treatment of hyperlipidemia and related disorders.

Dietary CLA‐induced Lipolysis Is Delayed in Soy Oil‐Fed Mice Compared to Coconut Oil‐Fed Mice

Conjugated linoleic acid (CLA) has been shown to cause a reduction in obesity in several species. CLA-induced body fat loss is enhanced when mice are fed coconut oil (CO) and involves increased lipolysis. The objective of this paper was to determine if the CLA-induced lipolysis in mice fed with different oil sources was time-dependent. Mice were fed 7% soybean oil (SO) or CO diets for 6week and then supplemented with 0 or 0.5% CLA for 3, 7, 10 or 14days. Body fat and ex-vivo lipolysis was determined. Body fat was reduced by CO on day 7 (P<0.01) and in both CO and SO-fed mice (P<0.05) in response to CLA on d14. Lipolysis was increased by CLA in CO-fed mice (P<0.01) but not in SO-fed mice on day 7 and 10, but on day 14 CLA increased lipolysis in both CO- and SO-fed mice (P<0.001). Expression and activation level of proteins involved in lipolysis and lipogenesis was determined by western blotting and real-time PCR, respectively. No significant differences were detected in protein expression. CO-fed mice had greater fatty acid synthase and stearyl CoA desaturase 1 mRNA expression and less acetyl CoA carboxylase mRNA expression (P<0.01). Sterol regulatory binding protein 1c was decreased by CLA in CO-fed mice and increased in SO-fed mice (P<0.05). Malic enzyme expression was increased by CLA (P<0.001) and CO (P<0.01). Therefore, CLA-induced lipolysis occurs more rapidly in CO vs SO-fed mice and lipogenesis is decreased in CO-fed mice with CLA supplementation.

Abstract 4423: Implications for cardiotoxicity with targeted therapies.

Abstract Tyrosine kinase inhibitors (TKi) have greatly improved the treatment and prognosis of multiple cancer types. However, unexpected cardiotoxicity has arisen that was not wholly predicted by current FDA mandated pre-clinical tests. Thus a more robust tool to predict the cardiotoxic potential of these compounds is warranted. For this purpose, we developed a panel of in vitro tests in a clinically relevant human cardiomyocyte model that assesses drug impact on overall cardiac health (cell viability, apoptosis, and morphology), mitochondria and metabolic intactness (reactive oxygen species (ROS) generation, AMPK activity, and lipid accumulation), and electrophysiological function (impedance (beat rate) and ion channel blockage). To demonstrate the utility of our panel, we examined the effect of 4 FDA-approved TKi with known clinical outcome on cardiac health. The 3 drugs with known cardiac adverse events (crizotinib, sunitinib, and nilotinib) all proved to be cardiotoxic by our panel although each showed distinct mechanisms of toxicity. However erlotinib, a cardiac-safe drug that targets EGFR and is used primarily in non-small cell lung cancer (NSCLC), did not show any indications of toxicity. Surprisingly, the most cardiotoxic drug by our panel was crizotinib, an ALK/ MET inhibitor that has revolutionized treatment for ALK+ NSCLC patients. Crizotinib potently impaired overall cardiac health by increasing ROS and apoptosis but also impeded electrophysiological function by inducing ion channel blockage and reducing cardiac beat rate. Interestingly crizotinib also induced lipid and cholesterol accumulation which was shown to be correlated with increased expression of the sterol-regulatory binding protein (SREBP) pathway by transcriptome analysis. The multi-targeted TKi sunitinib (used in renal cell carcinoma and gastrointestinal stromal tumors) and nilotinib (used in chronic myelogenous leukemia) also showed unique cardiotoxicity profiles. In conclusion, our studies showed a distinct cardiotoxicity profile for each TKi that correlates with clinical outcome. These results suggest that caution should be taken with these TKi especially when used long-term or in the adjuvant setting. Furthermore, these effects may be exacerbated in patients with adverse cardiac genetic predispositions and studies are ongoing in our lab on patient-derived cardiac cell lines to investigate this possibility. This multi-parameter screening approach allows for a more complete assessment of the potential for drug-induced cardiotoxicity and may allow for earlier detection in the drug development process. In addition, understanding the mechanisms of cardiac toxicities may lead to the discovery of novel mitigation strategies and combination therapies to improve cardiac cell health during treatment with oncology therapies. Citation Format: Kimberly R. Doherty, Robert L. Wappel, Dominique R. Talbert, Patricia B. Trusk, Scott A. Shell, Diarmuid M. Moran, James W. Kramer, Arthur Brown, Sarah Bacus. Implications for cardiotoxicity with targeted therapies. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4423. doi:10.1158/1538-7445.AM2013-4423