RASAL1 induces to downregulate the SCD1, leading to suppression of cell proliferation in colon cancer via LXRα/SREBP1c pathway

BACKGROUND: Recent studies have confirmed that RASAL1 has an antitumor effect in many cancers, but its functional role and the molecular mechanism underlying in colon cancer has not been investigated. RESULTS: We collected human colon cancer tissues and adjacent non-tumor tissues, human colon cancer cell lines LoVo, CaCo2, SW1116, SW480 and HCT-116, and normal colonic mucosa cell line NCM460. RT-qPCR was used to detect the RASAL1 level in the clinical tissues and cell lines. In LoVo and HCT-116, RASAL1 was artificially overexpressed. Cell viability and proliferation were measured using CCK-8 assays, and cell cycle was detected via PI staining and flow cytometry analysis. RASAL1 significantly inhibited the cell proliferation via inducing cell cycle arrest, suppressed cell cycle associated protein expression, and decreased the lipid content and inhibited the SCD1 expression. Moreover, SCD1 overexpression induced and downregulation repressed cell proliferation by causing cell cycle arrest. Additionally, luciferase reporter assays were performed to confirm the direct binding between SREBP1c, LXRα; and SCD1 promoter, we also demonstrated that RASAL1 inhibit SCD1 3'-UTR activity. RASAL1 inhibited tumor growth in xenograft nude mice models and shows inhibitory effect of SCD1 expression in vivo. CONCLUSION: Taken together, we concluded that RASAL1 inhibited colon cancer cell proliferation via modulating SCD1 activity through LXRα/SREBP1c pathway.

Enrichment of Short-Chain Ceramides and Free Fatty Acids in the Skin Epidermis, Liver, and Kidneys of db/db Mice, a Type 2 Diabetes Mellitus Model

Patients with diabetes mellitus (DM) often suffer from diverse skin disorders, which might be attributable to skin barrier dysfunction. To explore the role of lipid alterations in the epidermis in DM skin disorders, we quantitated 49 lipids (34 ceramides, 14 free fatty acids (FFAs), and cholesterol) in the skin epidermis, liver, and kidneys of db/db mice, a Type 2 DM model, using UPLC-MS/MS. The expression of genes involved in lipid synthesis was also evaluated. With the full establishment of hyperglycemia at the age of 20 weeks, remarkable lipid enrichment was noted in the skin of the db/db mice, especially at the epidermis and subcutaneous fat bed. Prominent increases in the ceramides and FFAs (>3 fold) with short or medium chains (

Picroside II attenuates fatty acid accumulation in HepG2 cells via modulation of fatty acid uptake and synthesis

BACKGROUND/AIMS: Hepatic steatosis is caused by an imbalance between free fatty acids (FFAs) uptake, utilization, storage, and disposal. Understanding the molecular mechanisms involved in FFAs accumulation and its modulation could drive the development of potential therapies for Nonalcoholic fatty liver disease. The aim of the current study was to explore the effects of picroside II, a phytoactive found in Picrorhiza kurroa, on fatty acid accumulation vis-à-vis silibinin, a known hepatoprotective phytoactive from Silybum marianum. METHODS: HepG2 cells were loaded with FFAs (oleic acid:palmitic acid/2:1) for 20 hours to mimic hepatic steatosis. The FFAs concentration achieving maximum fat accumulation and minimal cytotoxicity (500 μM) was standardized. HepG2 cells were exposed to the standardized FFAs concentration with and without picroside II pretreatment. RESULTS: Picroside II pretreatment inhibited FFAs-induced lipid accumulation by attenuating the expression of fatty acid transport protein 5, sterol regulatory element binding protein 1 and stearoyl CoA desaturase. Preatreatment with picroside II was also found to decrease the expression of forkhead box protein O1 and phosphoenolpyruvate carboxykinase. CONCLUSIONS: These findings suggest that picroside II effectively attenuated fatty acid accumulation by decreasing FFAs uptake and lipogenesis. Picroside II also decreased the expression of gluconeogenic genes.

Sterculic Acid and Its Analogues Are Potent Inhibitors of Toxoplasma gondii

Toxoplasmosis is a serious disease caused by Toxoplasma gondii, one of the most widespread parasites in the world. Lipid metabolism is important in the intracellular stage of T. gondii. Stearoyl-CoA desaturase (SCD), a key enzyme for the synthesis of unsaturated fatty acid is predicted to exist in T. gondii. Sterculic acid has been shown to specifically inhibit SCD activity. Here, we examined whether sterculic acid and its methyl ester analogues exhibit anti-T. gondii effects in vitro. T. gondii-infected Vero cells were disintegrated at 36 hr because of the propagation and egress of intracellular tachyzoites. All test compounds inhibited tachyzoite propagation and egress, reducing the number of ruptured Vero cells by the parasites. Sterculic acid and the methyl esters also inhibited replication of intracellular tachyzoites in HFF cells. Among the test compounds, sterculic acid showed the most potent activity against T. gondii, with an EC50 value of 36.2 μM, compared with EC50 values of 248-428 μM for the methyl esters. Our study demonstrated that sterculic acid and its analogues are effective in inhibition of T. gondii growth in vitro, suggesting that these compounds or analogues targeting SCD could be effective agents for the treatment of toxoplasmosis.

Diet high in alpha-linolenic acid up-regulate PPAR-gamma gene expression in the liver of goats

Background There is little information on the effects of diets containing high α-linolenic acid (C18:3n-3) on liver lipid composition and lipogenic gene expressions. In this study fourteen goats (Capra aegagrus hircus) were fed either a flaxseed oil (FSO) supplemented diet containing high α-linolenic acid or a control diet without added flaxseed oil (CON) for 100-d to evaluate the effects on liver lipid composition and the gene expression of peroxisome proliferator-activated receptors (PPAR-α) and stearoyl-CoA-desaturase (SCD) in the liver. Results An increase in the levels of C18:3n-3 and C20:5n-3, C22:5n-3, C22:6n-3 was observed in the liver of FSO-treated goats. There was a significant (P < 0.05) up-regulation of PPAR-α gene expression and downregulation of SCD gene in the liver of goats fed the high α-linolenic acid diet. Conclusions In conclusion, genes associated with the control of fatty acid (FA) conversion (SCD and PPAR) were affected by the α-linolenic acid supplementation in the goat diet. It is suggested that PPAR-α is the key messenger responsible for the translation of nutritional stimuli into changes in hepatic gene expression.

Carnosic Acid Inhibits Lipid Accumulation in 3T3-L1 Adipocytes Through Attenuation of Fatty Acid Desaturation

BACKGROUND: Excess body fat accumulation contributes to the development of metabolic disorders that can cause adverse health effects. Carnosic acid (CA), a major bioactive component of rosemary (Rosemarinus officinalis), has been suggested to possess anti-adipogenic properties. The present study was conducted to elucidate the mechanism underlying the anti-adipogenic effects of CA. METHODS: 3T3-L1 pre-adipocytes were treated with CA (0.1, 1, and 10 muM) from day 0 to day 8 of differentiation. On day 8, biochemical markers of lipid accumulation and the degree of fatty acid desaturation were measured. RESULTS: Oil Red O staining results, triglyceride (TG) accumulation, and glycerol 3-phosphate dehydrogenase activity suggested that CA significantly inhibited lipid accumulation in 3T3-L1 adipocytes. CA significantly decreased mRNA expression of peroxisome proliferator-activated receptor-gamma, sterol regulatory element-binding protein 1, and CCAAT/enhancer binding protein-alpha in a dose-dependent manner. Moreover, it decreased the ratio of both C16:1/C16:0 and C18:1/C18:0, with reduced expression of stearoyl CoA desaturase 1 mRNA and protein. CONCLUSIONS: These results suggest that CA efficiently suppressed adipogenesis in 3T3-L1 adipocytes and its action, at least in part, is associated with the downregulation of adipogenesis-related genes and the fatty acid composition of TG accumulated in adipocytes.

SCD1 over-expression inhibits palmitic acid-induced apoptosis of rat BRL hepatocytes / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the protective mechanism of stearoyl-CoA desaturase 1 (SCD1) over-expression against the pro-apoptotic affects of palmitic acid on hepatocytes using the rat BRL cell line.</p><p><b>METHODS</b>Concentration effect curves were generated using the trypan blue exclusion test to assess the death rate of BRL cells upon exposure to a dilution series of palmitic acid. The multiplicity of infection (MOI) of a lentiviral expression vector, pGC-FU-GFP, was determined for the BRL cells. Unmanipulated BRL cells were divided into two groups: the non-palmitate groups were composed of ordinary cultured cells (CON) alone, infected with lentivirus empty expression vector (negative control, NC), and infected with lentivirus overexpressing SCD1 (SCD1-LV); the palmitate groups were composed of ordinary cultured cells plus palmitate (CON+) alone, infected with lentivirus empty expression vector plus palmitate (NC+), and infected with lentivirus overexpressing SCD1 plus palmitate (SCD1-LV+). SCD1 mRNA expression was detected by real-time PCR. Propidium iodide (PI) single-staining was used to detect apoptosis and assess the cell cycle. Inter-group differences were analyzed statistically.</p><p><b>RESULTS</b>The death rate of BRL cells increased significantly after 72 h of exposure to 400 mumol/L palmitate (P less than 0.01). The MOI of pGC-FU-GFP in BRL cells was 20. The expression of SCD1 was significantly higher in the SCD1-LV and SCD1-LV+ groups than in the respective controls (vs. CON: F = 289, P less than 0.01; vs. CON+: F = 1522, P less than 0.01). Palmitate exposure led to decreased expression of SCD1 (CON+ vs. CON, F = 22, P less than 0.05 and NC+ vs. NC: F = 34, P less than 0.05). The ratio of S stage cells was similar in all non-palmitate groups (CON, NC and SCD1-LV, P = 0.137). However, there was a significant apoptotic peak and lower ratio of S stage cells in the control palmitate groups (CON+ and NC+) and the activity of cell proliferation was decreased as well. The ratio of apoptotic cells was decreased significantly in the SCD1-LV+ group compared to the CON+ group (P less than 0.01).</p><p><b>CONCLUSION</b>The expression of SCD1 and its desaturation activity increased in BRL cells upon infection with the pGC-FU-SCD1-GFP lentiviral vector, suggesting that SCD1 over-expression can decrease palmitic acid-induced toxicity and apoptosis in hepatocytes.</p>

Fatty Acid Composition of Tissue Cultured Breast Carcinoma and the Effect of Stearoyl-CoA Desaturase 1 Inhibition / 한국유방암학회지

PURPOSE: Stearoyl-CoA desaturase 1 (SCD1) is a novel therapeutic target in various malignancies, including breast cancer. The present study was designed to investigate the effect of the pharmacologic inhibition of SCD1 on fatty acid composition in tissue explant cultures of human breast cancer and to compare these effects with those in adjacent nonneoplastic breast tissue. METHODS: Paired samples of tumor and adjacent noncancerous tissue were isolated from 12 patients with infiltrating ductal breast cancer. Samples were explant cultured in vitro, exposed to the highly selective SCD1 inhibitor CAY10566, and examined for fatty acid composition by gas liquid chromatography. The cytotoxic and antigrowth effects were evaluated by quantification of lactate dehydrogenase release and by sulforhodamine B (SRB) measurement, respectively. RESULTS: Breast cancer tissue samples were found to have higher levels of monounsaturated fatty acids (MUFA) (p<0.001) and arachidonic acid (20:4n-6, p<0.001) and a lower level of linoleic acid (18:2n-6, p=0.02) than the normal-appearing breast tissues. While exhibiting no evident cytotoxicity, treatment with the SCD1 inhibitor, CAY10566 (0.1-1 microM), for 48 hours significantly increased 18:2n-6 levels in both the tumor and adjacent normal-appearing tissue (approximately 1.2 fold, p<0.05). However, the breast cancer tissue samples showed significant increases in the levels of MUFA and 20:4n-6 compared to the normal-appearing breast tissues (p<0.05). The SRB growth assay revealed a higher rate of inhibition with the SCD1 inhibitor in breast cancer tissues than in normal-appearing tissues (p<0.01, 41% vs. 29%). The SCD1 inhibitor also elevated saturated fatty acid (1.46-fold, p=0.001) levels only in the tumor tissue explant. CONCLUSION: The fatty acid composition and response to SCD1 inhibition differed between the explant cultures from breast cancer and the adjacent normal-appearing tissue. Altered fatty acid composition induced by SCD1 inhibition may also, in addition to Delta9 desaturation, modulate other reactions in de novo fatty acid synthesis and lipogenesis, and subsequently affect the overall survival and progression of breast cancer.

Dietary carnosic acid suppresses hepatic steatosis formation via regulation of hepatic fatty acid metabolism in high-fat diet-fed mice

In this study, we examined the hepatic anti-steatosis activity of carnosic acid (CA), a phenolic compound of rosemary (Rosmarinus officinalis) leaves, as well as its possible mechanism of action, in a high-fat diet (HFD)-fed mice model. Mice were fed a HFD, or a HFD supplemented with 0.01% (w/w) CA or 0.02% (w/w) CA, for a period of 12 weeks, after which changes in body weight, blood lipid profiles, and fatty acid mechanism markers were evaluated. The 0.02% (w/w) CA diet resulted in a marked decline in steatosis grade, as well as in homeostasis model assessment of insulin resistance (HOMA-IR) index values, intraperitoneal glucose tolerance test (IGTT) results, body weight gain, liver weight, and blood lipid levels (P < 0.05). The expression level of hepatic lipogenic genes, such as sterol regulating element binding protein-1c (SREBP-1c), liver-fatty acid binding protein (L-FABP), stearoyl-CoA desaturase 1 (SCD1), and fatty acid synthase (FAS), was significantly lower in mice fed 0.01% (w/w) CA and 0.02% (w/w) CA diets than that in the HFD group; on the other hand, the expression level of beta-oxidation-related genes, such as peroxisome proliferator-activated receptor alpha (PPAR-alpha), carnitine palmitoyltransferase 1 (CPT-1), and acyl-CoA oxidase (ACO), was higher in mice fed a 0.02% (w/w) CA diet, than that in the HFD group (P < 0.05). In addition, the hepatic content of palmitic acid (C16:0), palmitoleic acid (C16:1), and oleic acid (C18:1) was significantly lower in mice fed the 0.02% (w/w) CA diet than that in the HFD group (P < 0.05). These results suggest that orally administered CA suppressed HFD-induced hepatic steatosis and fatty liver-related metabolic disorders through decrease of de novo lipogenesis and fatty acid elongation and increase of fatty acid beta-oxidation in mice.

Heterologous expression of stearoyl-CoA desaturase-1 in Lactococcus lactis NZ3900 / 生物工程学报

The possibility of heterologous expression of human Stearoyl-CoA Desaturase (scd1) was investigated. The scd1 encoding sequence was inserted into the pNZ8149 to generate the pNZ8149-scd1 expression plasmids. Then we introduced the pNZ8149-scd1 construct into the Lactococcus lactis NZ3900 to investigate its enzyme activity. The results show that heterologous expressed SCD1 enzyme resulted in a 92%-169% increase in the C16:1n-7 and a 53-127% increase in the C18:1n-7 (P<0.05). The SCD1 enzyme was capable of producing n-7 fatty acids in Lactococcus lactis efficiently. It also suggests that the fatty acid desaturases can be heterologous expressed in Lactococcus lactis to produce the helpful fatty acids.

Differentially expressed genes identified by microarray analysis following leptin treatment of hepatic stellate cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Liver fibrosis is the process through which numerous chronic liver diseases develop into liver cirrhosis. Leptin can activate hepatic stellate cells (HSCs) and play an important role in the formation of liver fibrosis. However, the process by which leptin activates HSCs is complicated, and research on this process is limited. The aim of this study was to explore the related changes in gene expression and the control mechanisms involved in leptin activated HSCs to understand the overall mechanism of liver fibrosis development.</p><p><b>METHODS</b>We cultivate rat HSCs, with and without stimulation by leptin, and extracted mRNA. Differentially expressed genes were detected by microarray analysis.</p><p><b>RESULTS</b>The differentially expressed genes identified included six upregulated genes and six downregulated genes. The representative upregulated genes included short chain dehydrogenase (CY5/CY3 = 2.265) and pulmonary surfactant protein A1 (CY5/CY3 = 2.036). The significant downregulated gene encoded hepatic stearoyl coenzyme A desaturase 1 (SCD-1) (CY5/CY3 = 0.351).</p><p><b>CONCLUSION</b>Leptin might mediate the molecular biological mechanisms of liver fibrosis.</p>

Study of the genes expression of SCD-2 and B-FABP in the mice brain of exercise-induced fatigue by genechip cDNA microarray / 中国应用生理学杂志

<p><b>AIM</b>By genechip cDNA microarray, the genes expressions of Stearoyl-coenzyme A desaturase (Scd-2) and brain fatty acid-binding protein (B-FABP) were studied in the central nervous system (CNS) of the mice to discuss the mechanism of exercise-induced fatigue.</p><p><b>METHODS</b>Building the model of fatigued animal and using the genechip cDNA microarray, the genes expressions were analyzed between the control group and fatigue group mice.</p><p><b>RESULTS</b>The genes expression of Scd-2 and B-FABP were obvious different in the brain of fatigued group mice than of control group.</p><p><b>CONCLUSION</b>Exercise-induced nerve center fatigue is correlated with genes expressions of lipid metabolism.</p>

Effect of interferon therapy on fatty acid saturation index in hepatitis C virus infection

The ratio of stearic to oleic acids, i.e. the fatty acid saturation index, in red blood cell membranes was assayed in 60 patients with chronic hepatitis C virus infection before and after interferon-alpha therapy. Results were compared with 20 healthy controls. Hepatitis C virus titre was also assayed before and after interferon-alpha therapy. Within 2-5 months following interferon-alpha therapy, a significant inverse correlation was observed between saturation index and hepatitis C virus load. We conclude that hepatitis C virus infection enhances the degree of desaturation of 18-carbon fatty acids and that interferon-alpha is involved in their metabolism by increasing the degree of saturation and subsequent decrease in membrane fluidity

Stearic acid desaturation in rat liver microsomes: stimulation by fatty acid biding protein

Una proteína soluble (Mr=12 000) similar a FABP es parcialmente purificada a partir de citosol de hígado de rata (15 veces, considerando su afinidad por ácido oleico) por precipitación con sulfato de amonio. Durante la incubación de microsomas de hígado de rata conteniendo cantidades similares de los ácidos esteátrico y oleico, con esta proteína, hubo una disociación selectiva del ácido oleico desde la membrana microsomal. Cuando se agrega a microsomas una fracción enriquecida en esta proteína se estimula la desaturación del ácido esteárico. Este efecto es eliminado si la proteína es presaturada con ácido oleico. Se sugiere que esta proteína estimula la desaturación del ácido esteárico por un mecanismo que involucra la remoción del producto de la reacción