Mangiferin promotes macrophage cholesterol efflux and protects against atherosclerosis by augmenting the expression of ABCA1 and ABCG1.

Mangiferin has been identified as a potent cardioprotective factor that enhances high-density lipoprotein cholesterol levels in plasma. The aim of this study was to investigate the impact of mangiferin on macrophage cholesterol efflux and the development of atherosclerosis. The results showed that mangiferin injection significantly decreased atherosclerotic plaque size, and reduced plasma levels of low-density lipoprotein cholesterol, triglyceride, and total cholesterol in apoE knockout mice, whereas reverse cholesterol transport efficiency and high-density lipoprotein cholesterol levels were enhanced. In vitro study showed that mangiferin prevented lipid accumulation and promoted [3H]-cholesterol efflux from acetylated LDL-loaded RAW264.7 macrophages with an increase in the expression of ATP binding cassette A1/G1 (ABCA1/G1), liver X receptor-α (LXRα) and peroxisome proliferator-activated receptor-γ (PPARγ). Moreover, transfection of PPARγ siRNA or LXRα siRNA markedly abolished the positive effects of mangiferin on ABCA1/G1 expression and cholesterol efflux. The opposite effects were observed after treatment with PPARγ agonist rosiglitazone or LXRα agonist T0901317. In conclusion, mangiferin may attenuate atherogenesis by promoting cholesterol efflux from macrophages via the PPARγ-LXRα-ABCA1/G1 pathway.

LncRNA ENST00000602558.1 regulates ABCG1 expression and cholesterol efflux from vascular smooth muscle cells through a p65-dependent pathway.

BACKGROUND AND AIMS: Long non-coding RNAs (lncRNAs) have proven to be involved in the progression of atherosclerosis and dyslipidemia. In addition, vascular smooth muscle cells (VSMCs) phenotype switching, including VSMCs-derived foam cells formation, plays a key role in the pathogenesis of atherosclerosis. LncRNA ENST00000602558.1, one of the differentially expressed lncRNAs between coronary artery disease (CAD) patients and healthy controls identified by our previous study, was located to TG and HDL susceptibility loci, but its role and underlying mechanism in the pathogenesis of atherosclerosis remain unclear. The present study aims to explore the role and underlying mechanism of ENST00000602558.1 in the regulation of cholesterol efflux from VSMCs. METHODS: ABCG1 mRNA and protein expression in VSMCs was detected using qRT-PCR and Western blot, respectively. ABCG1-mediated cholesterol efflux to HDL from VSMCs was measured by means of NBD-cholesterol fluorescence intensity. The binding of ENST00000602558.1 to p65 and p65 to ABCG1 promoter region was detected by RNA immunoprecipitation (RIP) assay and chromatin immunoprecipitation (ChIP) assay, respectively. RESULTS: Overexpression of ENST00000602558.1 downregulated ABCG1 mRNA and protein expression, while knockdown of ENST00000602558.1 upregulated ABCG1 mRNA and protein expression. Consistently, ENST00000602558.1 overexpression decreased ABCG1-mediated cholesterol efflux to HDL from VSMCs by 30.38% (p < 0.001), and knockdown of ENST00000602558.1 increased ABCG1-mediated cholesterol efflux to HDL from VSMCs by 30.41% (p = 0.001). In addition to cholesterol efflux, overexpression of ENST00000602558.1 increased lipid accumulation and TC/TG levels, while knockdown of ENST00000602558.1 decreased lipid accumulation and TC/TG levels in VSMCs. Furthermore, we confirmed that ENST00000602558.1 regulated ABCG1 expression and ABCG1-mediated cholesterol efflux from VSMCs through binding to p65. CONCLUSIONS: In conclusion, ENST00000602558.1 played an important role in mediating cholesterol efflux to HDL from VSMCs by regulating ABCG1 expression through binding to p65.

ABCG1 and Pgp identify drug resistant, self-renewing osteosarcoma cells.

Patients with osteosarcoma (OST) frequently relapse with drug resistant disease, consistent with the hypothesis that tumours contain a cancer stem-like cell (CSCs) population that survives chemotherapy to re-populate the tumour at local or metastatic sites. We describe a dual functional approach to isolate OST-CSCs and identify the ABC transporter proteins driving this population to reveal potential targets for the development of new treatments. OST-CSCs were isolated by selection in doxorubicin (OST-EC50 cells) and based on the ability to produce progeny from a single cell (HOS-EC50.SR cells). Pgp expression was increased in OST-EC50 cells, inducing resistance to doxorubicin, etoposide, vincristine and actinomycin D (p < 0.05). Increased expression of ABCG1 and Pgp protein in the HOS-EC50.SR cells induced resistance to etoposide and doxorubicin (p < 0.01), which was directly correlated with ABCG1 expression (r > 0.88, p < 0.001). Pgp expression is increased in both the HOS-EC50 cells where it mediates MDR and the HOS-EC50.SR populations, whereas ABCG1 was only upregulated in the self-renewing drug resistant HOS-EC50.SR cells. Targeting ABCG1 and Pgp may eradicate the drug resistant self-renewing OST-CSCs, leading to improved outcomes for patients with OST.

Placental mechanism of prenatal nicotine exposure-reduced blood cholesterol levels in female fetal rats.

Clinical studies showed that intrauterine growth retardation (IUGR) neonatus had lower cholesterol concentrations in cord blood, which might be associated with increased risk of metabolic syndrome and cardiovascular diseases in adulthood. We previously observed lower blood cholesterol levels in prenatal nicotine exposure (PNE)-induced IUGR fetal rats, and this study aimed to elucidate the placental mechanism. Pregnant Wistar rats were subcutaneously injected with nicotine (2.0 mg/kg⋅d) on gestational day 9-20. In vivo, PNE increased levels of total cholesterol (TCH), high-density lipoprotein-cholesterol (HDL-C) and low-density lipoprotein-cholesterol (LDL-C) in maternal serum, while decreased levels of TCH and LDL-C in female fetal serum. Meanwhile, the expression of scavenger receptor class B type 1 (SR-B1), ATP-binding cassette transporter A1 (ABCA1) and ATP-binding cassette transporter G1 (ABCG1) were decreased, and the expression of liver X receptor (LXR) α and ß were also decreased in female placentas. In vitro, nicotine (0.1-10 µM) reduced the expression of LXRα, LXRß, SR-B1, ABCA1 and ABCG1 in a concentration dependent manner, which could be annulled by nAChR antagonist and LXR agonist. Taken together, nicotine could inhibit the expression of SR-B1, ABCA1 and ABCG1 via nAChR and LXR α/ß in female placentas, finally leading to reduced blood cholesterol levels in fetal rats.

Dihydromyricetin ameliorates foam cell formation via LXRα-ABCA1/ABCG1-dependent cholesterol efflux in macrophages.

As the most abundant flavonoid in Ampelopsis grossedentata, the protective effects of dihydromyricetin on atherosclerosis have been well established, yet the detailed mechanisms are not fully understood. The aim of the present study was to examine the effect of dihydromyricetin on lipid accumulation and the underlying molecular mechanisms in macrophages and ApoE-/- mice. Incubation with dihydromyricetin significantly attenuated oxidized low-density lipoprotein (ox-LDL)-mediated cholesterol and lipid accumulation in THP-1-derived macrophages, which was due to increased cholesterol efflux. In addition, dihydromyricetin increased mRNA and protein expressions of ATP-binding cassette transporter A1 (ABCA1) and ABCG1 but had no effect on the mRNA and protein expressions of SR-A, CD36, or SR-BI involved in cholesterol homeostasis. Furthermore, the upregulation of ABCA1 and ABCG1 by dihydromyricetin depended on liver X receptor α (LXRα), as evidenced by an increase in the nuclear level of LXRα and its prevention of the expression of ABCA1 and ABCG1 after inhibition of LXRα activity by knockdown of LXRα expression with small interfering RNA (siRNA). Accordingly, dihydromyricetin-mediated suppression of cholesterol and lipid accumulation in macrophages was also abrogated by LXRα siRNA. Moreover, the lesion size of atherosclerosis was smaller in dihydromyricetin-treated ApoE-/- mice compared with the vehicle-treated mice, and the protein expression of CD36, SR-A, ABCA1, ABCG1 and LXRα in aortas was modulated similar to that observed in THP-1-derived macrophages. These data suggest that promotion of LXRα-ABCA1/ABCG1-dependent cholesterol efflux is crucial event in suppression of lipid accumulation by dihydromyricetin in the transformation of macrophage foam cells.

Functional interplay between liver X receptor and AMP-activated protein kinase α inhibits atherosclerosis in apolipoprotein E-deficient mice - a new anti-atherogenic strategy.

BACKGROUND AND PURPOSE: The liver X receptor (LXR) agonist T317 reduces atherosclerosis but induces fatty liver. Metformin activates energy metabolism by activating AMPKα. In this study, we determined if interactions between metformin and T317 could inhibit atherosclerosis without activation of hepatic lipogenesis. EXPERIMENTAL APPROACH: Apolipoprotein E-deficient mice were treated with T317, metformin or both agents, in a high-fat diet for 16 weeks. Then, samples of aorta, liver, macrophage and serum were collected to determine atherosclerotic lesions, fatty liver, lipid profiles and expression of related proteins. Techniques used included immunohistochemistry, histology, qRT-PCR and Western blot. KEY RESULTS: T317 inhibited en face and aortic root sinus lesions, and the inhibition was further enhanced by addition of metformin. Co-treatment with metformin and T317 increased lesion stability, by increasing collagen content, and reducing necrotic cores and calcification. Formation of macrophages/foam cells and their accumulation in arterial wall were inhibited by the co-treatment, which was accompanied by increased ABCA1/ABCG1 expression, reduced monocyte adhesion and apparent local proliferation of macrophages. Metformin blocked T317-induced fatty liver by inhibiting T317-induced hepatic LXRα nuclear translocation and expression of lipogenic genes and by activating AMPKα. Moreover, co-treatment with T317 and metformin improved triglyceride metabolism by inducing expression of adipose triglyceride lipase, hormone-sensitive lipase, PPARα and carnitine acetyltransferase and by inhibiting acyl-CoA:diacylglycerol acyltransferase 1 expression. CONCLUSIONS AND IMPLICATIONS: Co-treatment with T317 and metformin inhibited the development of atherosclerosis without activation of lipogenesis, suggesting that combined treatment with T317 and metformin may be a novel approach to inhibition of atherosclerosis.

Kuwanon G attenuates atherosclerosis by upregulation of LXRα-ABCA1/ABCG1 and inhibition of NFκB activity in macrophages.

BACKGROUND: Atherosclerosis is characterized by chronic inflammation in vascular wall. Previous studies suggest that Kuwanon G (KWG) exerts anti-inflammatory activities. However, the effect of KWG on atherosclerosis remains unexplored. AIMS: To explore whether KWG affects macrophage foam cell formation in vitro and atherogenesis in vivo. METHODS: RAW 264.7 macrophages were stimulated with ox-LDL for 24h to induce foam cell formation and treated with KWG. Foam cell formation was determined by ORO staining and enzymatic analysis. Pro-inflammatory cytokines mRNA levels were tested by Real-time PCR method. Further molecular mechanism was investigated using Western blot. In vivo, ApoE-/- mice were fed with high-fat diet and intraperitoneally injected with KWG. Atherosclerotic lesion was accessed by H&E and ORO staining. Plaque composition was evaluated by immunohistochemistry and Sirius Red staining. Serum lipid profile and inflammatory cytokines were evaluated by enzymatic method and ELISA. RESULTS: KWG significantly decreased intracellular lipid accumulation and inflammatory cytokines mRNA levels in macrophages through enhancing LXRα-ABCA1/ABCG1 pathway and inhibiting NFκB activation. Administrated with KWG remarkably reduced the atherosclerotic lesion areas and macrophage content in the plaque of high-fat diet fed ApoE-/- mice. KWG also reduced hyperlipidemia and serum inflammatory cytokines in vivo. CONCLUSION: Taken together, these data highlight that KWG can attenuate atherosclerosis through inhibiting foam cell formation and inflammatory response.

Doxorubicin enhances oxysterol levels resulting in a LXR-mediated upregulation of cardiac cholesterol transporters.

The anthracycline-mediated cardiotoxicity is still not completely understood. To examine the impact of cholesterol metabolism and transport in this context, cholesterol and oxysterol levels as well as the expression of the cholesterol transporters ABCA1 and ABCG1 were analyzed in doxorubicin-treated HL-1 murine cardiomyocytes as well as in mouse model for acute doxorubicin-induced cardiotoxicity. Doxorubicin-treated HL-1 cells exhibited enhanced cholesterol (153±20% of control), oxysterol (24S-hydroxycholesterol: 206±29% of control) and cholesterol precursor levels (lathosterol: 122±12% of control; desmosterol: 188±10% of control) indicating enhanced cholesterol synthesis. Moreover, abca1 and abcg1 were upregulated on mRNA, protein and functional level caused by a doxorubicin-mediated activation of the nuclear receptor LXR. In addition, the oxysterols not only induced the abca1 and abcg1 in HL-1 cells but also enhanced the expression of endothelin-1 and transforming growth factor-ß, which have already been identified as important factors in doxorubicin-induced cardiotoxicity. These in vitro findings were verified in a murine model for acute doxorubicin-induced cardiotoxicity, demonstrating elevated cardiac (2.1±0.2vs. 3.6±1.0ng/mg) and systemic cholesterol levels (105.0±8.4vs. 130.0±4.3mg/dl), respectively, as well as enhanced oxysterol levels such as cardiac 24S-hydroxycholesterol (2.1±0.2vs. 3.6±1.0ng/mg). In line with these findings cardiac mRNA expression of abca1 (303% of control) and abcg1 (161% of control) was induced. Taken together, our data demonstrate enhanced cholesterol and oxysterol levels by doxorubicin, resulting in a LXR-dependent upregulation of abca1 and abcg1. In this context, the cytotoxic effects of oxysterols and their impact on cardiac gene expression should be considered as an important factor in doxorubicin-induced cardiotoxicity.

Eicosapentaenoic acid membrane incorporation impairs cholesterol efflux from cholesterol-loaded human macrophages by reducing the cholesteryl ester mobilization from lipid droplets.

A diet containing a high n-3/n-6 polyunsaturated fatty acids (PUFA) ratio has cardioprotective properties. PUFAs incorporation into membranes influences the function of membrane proteins. We investigated the impact of the membrane incorporation of PUFAs, especially eicosapentaenoic acid (EPA) (C20:5 n-3), on the anti-atherogenic cholesterol efflux pathways. We used cholesteryl esters (CE)-loaded human monocyte-derived macrophages (HMDM) to mimic foam cells exposed to the FAs for a long period of time to ensure their incorporation into cellular membranes. Phospholipid fraction of EPA cells exhibited high levels of EPA and its elongation product docosapentaenoic acid (DPA) (C22:5 n-3), which was associated with a decreased level of arachidonic acid (AA) (C20:4 n-6). EPA 70µM reduced ABCA1-mediated cholesterol efflux to apolipoprotein (apo) AI by 30% without any alteration in ABCA1 expression. The other tested PUFAs, DPA, docosahexaenoic acid (DHA) (C22:6 n-3), and AA, were also able to reduce ABCA1 functionality while the monounsaturated oleic FA slightly decreased efflux and the saturated palmitic FA had no impact. Moreover, EPA also reduced cholesterol efflux to HDL mediated by the Cla-1 and ABCG1 pathways. EPA incorporation did not hinder efflux in free cholesterol-loaded HMDM and did not promote esterification of cholesterol. Conversely, EPA reduced the neutral hydrolysis of cytoplasmic CE by 24%. The reduced CE hydrolysis was likely attributed to the increase in cellular TG contents and/or the decrease in apo E secretion after EPA treatment. In conclusion, EPA membrane incorporation reduces cholesterol efflux in human foam cells by reducing the cholesteryl ester mobilization from lipid droplets.

Placental ABCA1 Expression Is Increased in Spontaneous Preterm Deliveries Compared with Iatrogenic Preterm Deliveries and Term Deliveries.

OBJECTIVE: Abnormal expression of ABCA1 and ABCG1 in the placenta can elicit lipid metabolism disorder and adverse pregnancy outcomes. However, whether it is associated with preterm delivery remains unclear. Our present study aimed to evaluate the relationship between abnormal expression of ABCA1 or ABCG1 and preterm delivery. METHODS: Maternal blood and placental tissues from women with spontaneous deliveries (SPD), iatrogenic deliveries (IPD), and term deliveries (TD) were collected. The lipid content and expression of ABCA1 and ABCG1 were subsequently measured. RESULTS: Compared with IPD and TD groups, the HDL, TD, LDL, and TC levels were lower in the maternal blood but higher (except TC) in the cord blood of the SPD group. The extracellular lipid content in the placentas of the SPD group was also notably lower relative to the IPD and TD groups. Moreover, the protein and mRNA expressions of ABCA1 in the placentas of the SPD group were significantly higher compared with the IPD and TD groups; however, there was no obvious difference among the three groups in the protein and mRNA expressions of ABCG1. CONCLUSIONS: Abnormal expression of ABCA1 may be associated with the dysregulation of placental lipid metabolism and the occurrence or development of SPD.

High-density lipoprotein from subjects with coronary artery disease promotes macrophage foam cell formation: role of scavenger receptor CD36 and ERK/MAPK signaling.

Although high-density lipoprotein is atheroprotective, it can become dysfunctional in chronic inflammatory conditions and increase cardiovascular risk. We previously demonstrated that HDL from subjects with documented coronary artery disease is dysfunctional and is pro-oxidant/proinflammatory in macrophages. Here we examined the influence of dysfunctional/proinflammatory HDL (piHDL) on lipid accumulation in human macrophages, in comparison to functional HDL (nHDL). Exposure of macrophages to piHDL, in contrast to nHDL, resulted in oxidative stress and marked uptake of lipids from piHDL, leading to the formation of foam cell phenotype as noted by oil red O staining with concomitant increase in total cellular cholesterol content. Using western blotting, we identified that piHDL profoundly upregulated the expression of scavenger receptor CD36 and suppressed the expression of ABCG1 and SRB1 in macrophages, thereby facilitating cholesterol influx capacity of macrophages. We then identified that CD36 did not act alone, indeed it was activated in macrophages along with ERK/MAPK, in response to piHDL, which in turn led to lipid accumulation as well as proinflammatory response via activation of NFkB and subsequent release of proinflammatory markers-TNF-ά and MMP-9. These effects were confirmed using pharmacological inhibitors for either CD36 or ERK/MAPK. Furthermore, piHDL treatment moderately activated PPAR-γ and Nrf2, the known regulators of CD36 in macrophages, suggesting that the two forms of HDL differentially regulate CD36 expression. Taken together, the results demonstrate that a novel CD36-ERK/MAPK-dependent mechanism is involved in macrophage lipid accumulation by piHDL, there by revealing the importance of functional deficiency in HDL and its potential link to atherogenesis.

Advanced glycation end products increase lipids accumulation in macrophages through upregulation of receptor of advanced glycation end products: increasing uptake, esterification and decreasing efflux of cholesterol.

BACKGROUND: Previous reports have suggested that advanced glycation end products (AGEs) participate in the pathogenesis of diabetic macroangiopathy. Our previous study have found that AGEs can increase the lipid droplets accumulation in aortas of diabetic rats, but the current understanding of the mechanisms remains incomplete by which AGEs affect lipids accumulation in macrophages and accelerate atherosclerosis. In this study, we investigated the role of AGEs on lipids accumulation in macrophages and the possible molecular mechanisms including cholesterol influx, esterification and efflux of macrophages. METHODS: THP-1 cells were incubated with PMA to differentiate to be macrophages which were treated with AGEs in the concentration of 300 µg/ml and 600 µg/ml with or without anti-RAGE (receptor for AGEs) antibody and then stimulated by oxidized-LDL (oxLDL) or Dil-oxLDL. Lipids accumulation was examined by oil red staining. The cholesterol uptake, esterification and efflux were detected respectively by fluorescence microscope, enzymatic assay kit and fluorescence microplate. Quantitative RT-PCR and Western blot were used to measure expression of the moleculars involved in cholesterol uptake, synthesis/esterification and efflux. RESULTS: AGEs increased lipids accumulation in macrophages in a concentration-dependent manner. 600 µg/ml AGEs obviously upregulated oxLDL uptake, increased levels of cholesterol ester in macrophages, and decreased the HDL-mediated cholesterol efflux by regulating the main molecular expression including CD36, Scavenger receptors (SR) A2, HMG-CoA reductase (HMGCR), ACAT1 and ATP-binding cassette transporter G1 (ABCG1). The changes above were inversed when the cells were pretreated with anti-RAGE antibody. CONCLUSIONS: The current study suggest that AGEs can increase lipids accumulation in macrophages by regulating cholesterol uptake, esterification and efflux mainly through binding with RAGE, which provide a deep understanding of mechanisms how AGEs accelerating diabetic atherogenesis.

MEK1/2 inhibitors activate macrophage ABCG1 expression and reverse cholesterol transport-An anti-atherogenic function of ERK1/2 inhibition.

Expression of ATP-binding cassette transporter G1 (ABCG1), a molecule facilitating cholesterol efflux to HDL, is activated by liver X receptor (LXR). In this study, we investigated if inhibition of ERK1/2 can activate macrophage ABCG1 expression and functions. MEK1/2 inhibitors, PD98059 and U0126, increased ABCG1 mRNA and protein expression, and activated the natural ABCG1 promoter but not the promoter with the LXR responsive element (LXRE) deletion. Inhibition of ABCG1 expression by ABCG1 siRNA did enhance the formation of macrophage/foam cells and it attenuated the inhibitory effect of MEK1/2 inhibitors on foam cell formation. MEK1/2 inhibitors activated macrophage cholesterol efflux to HDL in vitro, and they enhanced reverse cholesterol transport (RCT) in vivo. ApoE deficient (apoE(-/-)) mice receiving U0126 treatment had reduced sinus lesions in the aortic root which was associated with activated macrophage ABCG1 expression in the lesion areas. MEK1/2 inhibitors coordinated the RXR agonist, but not the LXR agonist, to induce ABCG1 expression. Furthermore, induction of ABCG1 expression by MEK1/2 inhibitors was associated with activation of SIRT1, a positive regulator of LXR activity, and inactivation of SULT2B1 and RIP140, two negative regulators of LXR activity. Taken together, our study suggests that MEK1/2 inhibitors activate macrophage ABCG1 expression/RCT, and inhibit foam cell formation and lesion development by multiple mechanisms, supporting the concept that ERK1/2 inhibition is anti-atherogenic.

Detection and Functional Analysis of Tumor-Derived LXR Ligands.

There is growing evidence highlighting the ability of nuclear receptors to control not only metabolism, but also inflammation and cancer progression. In particular liver X receptors (LXRs), the nuclear receptors physiologically involved in cholesterol homeostasis, have been shown to regulate innate and adaptive immune responses in many pathological conditions, including cancer.We have recently demonstrated that LXR ligands (oxysterols) released by tumor cells may have an immunomodulatory role, affecting the immune cells involved in the antitumor immune response. Indeed, oxysterols inhibit the expression of the chemokine receptor CCR7 on dendritic cells (DC) in an LXR-dependent manner, thus impairing DC migration to secondary lymphoid organs, and therefore dampening the induction of successful antitumor responses.We have resorted to direct (i.e., luciferase-based LXR activation assay) and indirect (i.e., activation of LXR target genes in dendritic cells) methods in order to assess the presence of LXR ligands (oxysterols) in tumor-conditioned media.These two methods are also suitable to study strategies to block oxysterol release by tumor cells.

VISFATIN PROMOTES FOAM CELL FORMATION BY DYSREGULATING CD36, SRA, ABCA1, AND ABCG1 EXPRESSION IN RAW264.7 MACROPHAGES.

BACKGROUND: Visfatin is produced in and secreted from adipocytes. Increased circulating visfatin level is observed in obese subjects. Previous studies demonstrated that visfatin was involved in obesity-related cardiovascular diseases. AIMS: This study aims to explore the regulatory effects of adipokine visfatin on foam cell formation, a key step in the development of atherosclerosis. METHODS: Effect of visfatin on protein and mRNA expression of scavenger receptor and ATP binding cassette transporter in RAW264.7 macrophages were measured by western blotting and real-time RT-PCR. To confirm the influence of visfatin-regulated scavenger receptor and ATP binding cassette transporter to foam cell formation, the visfatin-caused changes of ox-LDL uptake, cholesterol efflux, and foam cell formation were determined. RESULTS: Visfatin significantly increased the expression of CD36 and scavenger receptor A (SRA), decreased the expression of ATP-binding cassette transporters A1 (ABCA1) and G1 (ABCG1), and had no effect on the expression of SR-B1. Visfatin increased oxidized-LDL (ox-LDL) uptake and decreased cholesterol efflux, which increased foam cell formation. The PI3K inhibitor LY294002 blocked the effect of visfatin on the protein and mRNA expression levels of CD36, SRA, and ABCG1 and ox-LDL uptake and cholesterol efflux. The ERK inhibitor PD98059 also prevented visfatin-induced ABCA1 instability and subsequently decreased cholesterol efflux. CONCLUSIONS: Visfatin upregulated CD36 and SRA expression and downregulated ABCA1 and ABCG1 expression, subsequently increased ox-LDL uptake and decreased cholesterol efflux, and finally promoted foam cell formation via the PI3K- and ERK-dependent pathways.