Fluvastatin is effective against thymic carcinoma.

AIMS: Thymic carcinoma is a rare epithelial tumor, for which, optimal pharmacotherapeutic methods have not yet been established. To develop new drug treatments for thymic carcinoma, we investigated the effects of fluvastatin-mediated pharmacological inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) on thymic carcinoma. MAIN METHODS: Thymic carcinoma tissue was surgically excised and HMGCR expression was assessed by immunohistochemistry. Ty82 human thymic carcinoma cells were treated with fluvastatin (1-10 µM) and their growth was monitored. KEY FINDINGS: HMGCR was expressed on carcinoma cells but not on normal epithelial cells in thymic tissue. Inhibition of HMGCR by fluvastatin suppressed cell proliferation and induced the death of Ty-82 human thymic carcinoma cells. Fluvastatin mediated its antitumor effects by blocking the production of geranylgeranyl-pyrophosphate (GGPP), an isoprenoid that is produced from mevalonate and binds to small GTPases, which promotes cell proliferation. SIGNIFICANCE: Fluvastatin showed marked antitumor effects on thymic carcinoma. The results suggest that the statin has clinical benefits in thymic carcinoma management.

SREBP2 is upregulated in esophageal squamous cell carcinoma and co­operates with c­Myc to regulate HMGCR expression.

Dysregulations of the mevalonate pathway (MVA) have been previously identified. Our previous study demonstrated that 3­hydroxy­3­methylglutaryl­coenzyme A reductase (HMGCR), the rate­limiting enzyme of the MVA pathway, was upregulated in esophageal squamous cell carcinoma (ESCC) and statin­inhibited ESCC tumorigenesis. However, the underlying mechanism of HMGCR regulation in ESCC remains unknown. In the present study, western blotting and immunohistochemistry analysis demonstrated that sterol regulatory element­binding protein 2 (SREBP2), the master regulator for HMGCR, was upregulated in ESCC clinical samples. Overexpression of SREBP2 expression in ESCC cell lines promoted the growth, migration and colony formation of cancer cells in the MTT, Boyden chamber and soft agar assays, respectively, which was inhibited by lovastatin. Downregulation of SREBP2 expression in ESCC cell lines inhibited the viability, and migration and colony formation abilities of cancer cells. Assessment of the molecular mechanism demonstrated that SREBP2 interacted with c­Myc and cooperated with c­Myc to activate HMGCR expression. Collectively, the present study identified SREBP2 as an oncogene associated with the tumorigenesis of ESCC and further demonstrated the therapeutic effects of statins in ESCC.

HMG CoA reductase expression as a prognostic factor in Korean patients with breast cancer: A retrospective study.

There are many preclinical and epidemiological reports suggesting a correlation between 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoAR) or HMG-CoAR inhibitor (statin) treatment and prognosis in breast cancer. This study aimed to investigate the expression of HMG-CoAR in Korean patients with breast cancer.The expression of HMG-CoAR on tissue microarrays from 191 patients who underwent resection from 2005 to 2006 in the Pusan National University Hospital was assessed by immunohistochemistry (IHC). The IHC assessment by a board-certified pathologist included areas of both carcinoma and peritumoral tissue of the breast. The scores of cancer-specific staining were adjusted by the scores of peritumoral staining.The patients were followed for a median 9.1 years. Disease-free survival (DFS) was shorter in patients with a positive adjusted HMG-CoAR score by log-rank test (not reached vs 11.6 years, P = .011). After adjusting for age, T stage, N stage, pathological grade, perioperational chemotherapy, adjuvant radiotherapy, estrogen receptor positivity, progesterone receptor positivity, human epidermal growth factor receptor-2 positivity, and high Ki-67 (>10%), a positive adjusted HMG-CoAR IHC score was also associated with shorter DFS (hazard ratio = 2.638, 95% confidence interval [CI] 1.112-6.262, P = .028).The expression of HMG-CoAR might be an independent prognostic factor in breast cancer. There are established drugs targeting HMG-CoAR, and further studies on its potential as a predictive marker are needed.

Induction of 3-hydroxy-3-methylglutaryl-CoA reductase mediates statin resistance in breast cancer cells.

The mevalonate pathway has emerged as a promising target for several solid tumors. Statins are inhibitors of the 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), the rate-limiting enzyme of this pathway, and are commonly used to treat patients with hypercholesterolemia. Pleiotropic antitumor mechanisms of statins have been demonstrated for several human cancer types. However, cancer cells differ in their individual statin sensitivity and some cell lines have shown relative resistance. In this study we demonstrate, that the human breast cancer cell lines MDA-MB-231, MDA-MB-468, MCF-7, and T47D are differentially affected by statins. Whereas the vitality of MDA-MB-231 and MDA-MB-468 cells was reduced by up to 60% using atorvastatin, simvastatin, or rosuvastatin (p < 0.001), only marginal effects were seen in T47D and MCF-7 cells following exposure to statins. Statin treatment led to an upregulation of HMGCR mRNA and protein expression by up to sixfolds in the statin-resistant cells lines (p < 0.001), but no alterations of HMGCR were observed in the statin-sensitive MDA-MB-231 and MDA-MB-468 cells. The knockdown of HMGCR prior to statin treatment sensitized the resistant cell lines, reflected by a 70% reduction in vitality, increased apoptotic DNA fragmentation (sixfold) and by accumulation of the apoptosis marker cleaved poly-ADP ribose polymerase. Statins induced a cleavage of the sterol-regulatory element-binding protein (SREBP)-2, a transcriptional activator of the HMGCR, in T47D and MCF-7 cells. The inhibition of SREBP-2 activation by co-administration of dipyridamole sensitized MCF-7 and T47D cells for statins (loss of vitality by 80%; p < 0.001). Furthermore, assessment of a statin-resistant MDA-MB-231 clone, generated by long-term sublethal statin exposure, revealed a significant induction of HMGCR expression by up to 12-folds (p < 0.001). Knockdown of HMGCR restored statin sensitivity back to levels of the parental cells. In conclusion, these results indicate a resistance of cancer cells against statins, which is in part due to the induction of HMGCR.

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.

Hsp90 and hepatobiliary transformation during sea lamprey metamorphosis.

BACKGROUND: Biliary atresia (BA) is a human infant disease with inflammatory fibrous obstructions in the bile ducts and is the most common cause for pediatric liver transplantation. In contrast, the sea lamprey undergoes developmental BA with transient cholestasis and fibrosis during metamorphosis, but emerges as a fecund adult. Therefore, sea lamprey liver metamorphosis may serve as an etiological model for human BA and provide pivotal information for hepatobiliary transformation and possible therapeutics. RESULTS: We hypothesized that liver metamorphosis in sea lamprey is due to transcriptional reprogramming that dictates cellular remodeling during metamorphosis. We determined global gene expressions in liver at several metamorphic landmark stages by integrating mRNA-Seq and gene ontology analyses, and validated the results with real-time quantitative PCR, histological and immunohistochemical staining. These analyses revealed that gene expressions of protein folding chaperones, membrane transporters and extracellular matrices were altered and shifted during liver metamorphosis. HSP90, important in protein folding and invertebrate metamorphosis, was identified as a candidate key factor during liver metamorphosis in sea lamprey. Blocking HSP90 with geldanamycin facilitated liver metamorphosis and decreased the gene expressions of the rate limiting enzyme for cholesterol biosynthesis, HMGCoA reductase (hmgcr), and bile acid biosynthesis, cyp7a1. Injection of hsp90 siRNA for 4 days altered gene expressions of met, hmgcr, cyp27a1, and slc10a1. Bile acid concentrations were increased while bile duct and gall bladder degeneration was facilitated and synchronized after hsp90 siRNA injection. CONCLUSIONS: HSP90 appears to play crucial roles in hepatobiliary transformation during sea lamprey metamorphosis. Sea lamprey is a useful animal model to study postembryonic development and mechanisms for hsp90-induced hepatobiliary transformation.

The Flavone Luteolin Suppresses SREBP-2 Expression and Post-Translational Activation in Hepatic Cells.

High blood cholesterol has been associated with cardiovascular diseases. The enzyme HMG CoA reductase (HMGCR) is responsible for cholesterol synthesis, and inhibitors of this enzyme (statins) have been used clinically to control blood cholesterol. Sterol regulatory element binding protein (SREBP) -2 is a key transcription factor in cholesterol metabolism, and HMGCR is a target gene of SREBP-2. Attenuating SREBP-2 activity could potentially minimize the expression of HMGCR. Luteolin is a flavone that is commonly detected in plant foods. In the present study, Luteolin suppressed the expression of SREBP-2 at concentrations as low as 1 µM in the hepatic cell lines WRL and HepG2. This flavone also prevented the nuclear translocation of SREBP-2. Post-translational processing of SREBP-2 protein was required for nuclear translocation. Luteolin partially blocked this activation route through increased AMP kinase (AMPK) activation. At the transcriptional level, the mRNA and protein expression of SREBP-2 were reduced through luteolin. A reporter gene assay also verified that the transcription of SREBF2 was weakened in response to this flavone. The reduced expression and protein processing of SREBP-2 resulted in decreased nuclear translocation. Thus, the transcription of HMGCR was also decreased after luteolin treatment. In summary, the results of the present study showed that luteolin modulates HMGCR transcription by decreasing the expression and nuclear translocation of SREBP-2.

Differentiation and apoptosis induction by lovastatin and γ-tocotrienol in HL-60 cells via Ras/ERK/NF-κB and Ras/Akt/NF-κB signaling dependent down-regulation of glyoxalase 1 and HMG-CoA reductase.

Glyoxalase 1 (GLO1) and HMG-CoA reductase (HMGCR) are highly expressed in most tumor cells and little in normal cells. In this study, treatment of HL-60 cells with lovastatin induced characteristic apoptosis in a dose-dependent manner. We demonstrated that lovastatin treatment inhibited Ras and Raf protein translocation to cell membrane and eliminated the phosphorylation of the downstream effectors Akt and ERK, and the subsequent NF-κB translocation into nucleus. Specific inhibitors and γ-tocotrienol confirmed the Ras/Raf/ERK/NF-κB/GLO1 and Ras/Akt/NF-κB/GLO1 pathways. Data revealed that lovastatin induced HL-60 cell death was attenuated by mevalonate treatment. We demonstrated also that γ-tocotrienol showed its apoptotic effect on the HL-60 cell through the same pathway. γ-Tocotrienol enhanced the apoptotic effect of lovastatin through the down-regulation of GLO1 and HMGCR resulting in an increase of methylglyoxal and a decrease of cholesterol and led to the apoptosis of HL-60 cells. Data also revealed that both lovastatin and gamma-tocotrienol induced significant HL-60 cell differentiation. These results suggest that both lovastatin and gamma-tocotrienol could induce differentiation and followed by apoptosis.

Malignant fibrous histiocytoma of visceral organs: clinicopathologic features and diagnostic value of ezrin and HMG-CoA reductase.

Malignant fibrous histiocytoma (MFH) of the breast and visceral organs is extremely rare. There is an incomplete understanding of the clinical pathology of the primary MFH originating from the breast and visceral organs, especially in comparison with other soft tissue sarcomas. As a consequence we searched and analyzed the clinical and pathological records of all the nine patients with diagnosed breast and visceral MFH in our hospital. Immunohistochemical staining was performed for ezrin and HMG-CoA reductase in these MFH cases and relevant mesenchymal sarcomas. The 9 MFH cases presented with nonspecific symptoms and imaging manifestations. 6 cases were classified as storiform-pleomorphic MFH, 2 cases as inflammatory MFH, and the remaining 1 case as giant cell MFH. The results showed that ezrin expression, as well as HMG-CoA reductase expression, was significantly stronger in MFH cases than other non-MFH sarcomas. Poor prognosis seemed to be associated with younger age. Certain characteristics and clinicopathologic features can help us making the diagnosis of MFH. In conclusion, our study provided the potential value of ezrin and HMG-CoA reductase for diagnosis and differential diagnosis of MFH located in the breast and visceral organs. More accurate prognostic information of this rare disease needed to be further investigated.

Inflammatory Stress Exacerbated Mesangial Foam Cell Formation and Renal Injury via Disrupting Cellular Cholesterol Homeostasis.

Inflammation and lipids play significant roles in the progression of chronic kidney disease. This study was designed to investigate whether inflammation disrupts cellular cholesterol homeostasis and causes the lipid nephrotoxicity in vitro and in vivo, and explored its underlying mechanisms. Inflammatory stress was induced by cytokines (interleukin-1ß (IL-1ß); tumor necrosis factor α (TNF-α)) to human mesangial cells (HMCs) in vitro and by subcutaneous casein injection in C57BL/6J mice in vivo. The data showed that inflammatory stress exacerbated renal cholesterol ester accumulation in vitro and in vivo. Inflammation increased cellular cholesterol uptake and synthesis via upregulating the expression of low-density lipoprotein receptor (LDLr) and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCoA-R), while it decreased cholesterol efflux via downregulating the expression of liver X receptor alpha and ATP-binding cassette transporter A1. The increased lipid accumulation by inflammatory stress induced reactive oxygen species (ROS) and increased levels of endoplasmic reticulum (ER) stress markers (inositol-requiring protein 1 and activating transcription factor 6) in HMCs and kidneys of C57BL/6J mice. This study implied that inflammation promoted renal lipid accumulation and foam cell formation by disrupting cellular cholesterol homeostasis. Increased intracellular lipids under inflammatory stress caused oxidative stress and ER stress in vitro and in vivo which may contribute to renal injury and progression of chronic kidney disease.

Transmembrane protein 55B is a novel regulator of cellular cholesterol metabolism.

OBJECTIVE: Interindividual variation in pathways affecting cellular cholesterol metabolism can influence levels of plasma cholesterol, a well-established risk factor for cardiovascular disease. Inherent variation among immortalized lymphoblastoid cell lines from different donors can be leveraged to discover novel genes that modulate cellular cholesterol metabolism. The objective of this study was to identify novel genes that regulate cholesterol metabolism by testing for evidence of correlated gene expression with cellular levels of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) mRNA, a marker for cellular cholesterol homeostasis, in a large panel of lymphoblastoid cell lines. APPROACH AND RESULTS: Expression array profiling was performed on 480 lymphoblastoid cell lines established from participants of the Cholesterol and Pharmacogenetics (CAP) statin clinical trial, and transcripts were tested for evidence of correlated expression with HMGCR as a marker of intracellular cholesterol homeostasis. Of these, transmembrane protein 55b (TMEM55B) showed the strongest correlation (r=0.29; P=4.0E-08) of all genes not previously implicated in cholesterol metabolism and was found to be sterol regulated. TMEM55B knockdown in human hepatoma cell lines promoted the decay rate of the low-density lipoprotein receptor, reduced cell surface low-density lipoprotein receptor protein, impaired low-density lipoprotein uptake, and reduced intracellular cholesterol. CONCLUSIONS: Here, we report identification of TMEM55B as a novel regulator of cellular cholesterol metabolism through the combination of gene expression profiling and functional studies. The findings highlight the value of an integrated genomic approach for identifying genes that influence cholesterol homeostasis.

Involvement of hepatic IL-1 in the strain-dependent sex differences in serum total cholesterol levels in rats.

The strain and sex differences in serum total cholesterol (TC) levels were examined in F344 and Sprague-Dawley (SD) rats. A sex difference (male

Simvastatin delay progression of pancreatic intraepithelial neoplasia and cancer formation in a genetically engineered mouse model of pancreatic cancer.

BACKGROUND AND AIMS: Pancreatic cancer is among the most dismal of human malignancies. There are no chemopreventive strategies for pancreatic cancer or its precursor lesions, pancreatic intraepithelial neoplasia (PanINs). Recent evidence suggests that statins have potential chemopreventive abilities. In this study, we used a genetically engineered mouse model of pancreatic cancer to evaluate the chemopreventive potential of this drug. METHODS: Simvastatin was injected i.p. in LsL-Kras(G12D); Pdx1-Cre or LsL-Kras(G12D);LsL-Trp53(R172H);Pdx1-Cre mice. After five months, animals were sacrificed. The effect of simvastatin was evaluated by histopathological analyses, immunostaining, and real-time PCR. RESULTS: After five months of treatment, simvastatin was able to significantly delay progression of mPanINs in LsL-Kras(G12D); Pdx1-Cre mice. Furthermore, formation of invasive pancreatic cancer in LsL-Kras(G12D); LsL-Trp53(R172H); Pdx1-Cre transgenic mice was partially inhibited by simvastatin. Invasive murine pancreatic cancer was identified in 9 of 12 (75%) LsL-Kras(G12D); LsL-Trp53(R172H);Pdx1-Cre untreated control mice. In contrast, transgenic mice treated with Simvastatin, only 4 out of 10 (40%, p = 0.004) developed murine pancreatic cancer during the study. Using real-time PCR we found a significant up-regulation of Hmgcr as sign of blocking HMG-CoA reductase, a key enzyme in the cholesterol biosynthesis. This shows our ability to achieve effective pharmacologic levels of simvastatin during pancreatic cancer formation in vivo. CONCLUSION: Using a transgenic mouse model that recapitulates human pancreatic cancer, this study provides first evidence that simvastatin is an effective chemopreventive agent by delaying the progression of PanINs and partially inhibit the formation of murine pancreatic cancer.

Transcriptional and posttranscriptional inhibition of HMGCR and PC biosynthesis by geraniol in 2 Hep-G2 cell proliferation linked pathways.

Geraniol, present in the essential oils of many aromatic plants, has in vitro and in vivo antitumor activity against several cell lines. We investigated the effects of geraniol on lipid metabolic pathways involved in Hep-G2 cell proliferation and found that geraniol inhibits the mevalonate pathway, phosphatidylcholine biosynthesis, cell growth, and cell cycle progression (with an arrest occurring at the G0/G1 interphase) and increases apoptosis. The expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), the rate-limiting step in cholesterol synthesis, was inhibited at the transcriptional and posttranscriptional levels, as assessed by real-time RT-PCR, Western blots, and [(14)C]HMG-CoA-conversion radioactivity assays. That geraniol decreased cholesterogenesis but increased the incorporation of [(14)C]acetate into other nonsaponifiable metabolites indicated the existence of a second control point between squalene and cholesterol involved in redirecting the flow of cholesterol-derived carbon toward other metabolites of the mevalonate pathway. That exogenous mevalonate failed to restore growth in geraniol-inhibited cells suggests that, in addition to the inhibition of HMGCR, other dose-dependent actions exist through which geraniol can impact the mevalonate pathway and consequently inhibit cell proliferation. These results suggest that geraniol, a nontoxic compound found in many fruits and herbs, exhibits notable potential as a natural agent for combatting cancer and (or) cardiovascular diseases.

Albusin B modulates lipid metabolism and increases antioxidant defense in broiler chickens by a proteomic approach.

BACKGROUND: The present study was designed to investigate the effect of albusin B on lipid metabolism and antioxidant defense in broiler chickens by a proteomic approach. The bacteriocin, albusin B of Ruminococcus albus 7, expressed by yeast was applied in this study. Three dietary treatments, consisting of the basal diet (control), basal diet + albusin B (2.5 g kg⁻¹), and basal diet + nosiheptide (2.5 mg kg⁻¹) were randomly fed to 90 broiler chickens from 1 to 35 days of age, respectively. After 35 days of supplementation, the growth performance, lipid metabolism and antioxidant proteins in the jejunum and liver, intestinal protein profile, and plasma lipid profile were analyzed. RESULTS: Broilers with albusin B supplementation had greater body weight than the control broilers. Compared with the control broilers, lower triglyceride and higher high-density lipoprotein concentration in the blood were observed in both broilers with albusin B and nosiheptide supplementation. In addition, albusin B suppressed the mRNA expression of fatty acid binding protein 2 and ATP binding cassette transporter G 5 in the jejunum. In the jejunal protein profiles, four antioxidant proteins were upregulated by albusin B and nosiheptide treatments. The jejunal antioxidant gene expression had a concordant pattern. Hepatic genes related to lipid metabolism, 3-hydroxy-3-methyl-glutaryl CoA reductase, and superoxide dismutase were upregulated by albusin B supplementation. CONCLUSION: Albusin B supplementation modulated lipid metabolism and activated systemic antioxidant defense, which might partially contribute to the performance of broiler chickens.

Alteration of lipids and the transcription of lipid-related genes in myelodysplastic syndromes via a TP53-related pathway.

Myelodysplastic syndromes (MDS) are clonal stem cell diseases of the bone marrow characterized by abnormalities in maturation of hematopoietic cells of all lineages. MDS patients frequently have lower lipids and high rates of apoptosis and p53 (TP53) expression. An association between the reduced lipids in MDS and the expression of lipid-related genes was sought. We further evaluated whether 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGcoAR) and low-density lipoprotein receptor (LDL-R) are regulated by TP53 in vivo and in vitro. Gene expression was measured using real-time reverse transcription polymerase chain reaction on RNA extracted from bone marrow and peripheral blood from eight newly diagnosed MDS patients and eight controls and from mice livers. Serum lipid profile was measured using colorimetric enzymatic procedures. Total- and LDL cholesterol were lower in MDS patients in comparison to controls (p = 0.04 and p = 0.01, respectively). HMGcoAR messenger RNA increased in peripheral blood and bone marrow of MDS patients compared to controls (p = 0.04 and p = 0.01, respectively). LDL-R messenger RNA was higher only in the peripheral blood of MDS patients (p = 0.05). Comparable results were obtained in vivo. The transcription of these genes correlates with TP53 activation as documented by p21 messenger RNA elevation, a surrogate for TP53 activation and by using TP53 temperature-sensitive cells treated with adriamycin. To conclude, an association between reduced lipids in MDS and expression of HMGcoAR and LDL-R genes was documented. The transcription of these genes can be regulated by TP53.

Linalool reduces the expression of 3-hydroxy-3-methylglutaryl CoA reductase via sterol regulatory element binding protein-2- and ubiquitin-dependent mechanisms.

We investigated hypocholesterolemic mechanisms of linalool, an aromatic anti-oxidative monoterpene, which is abundant in teas and essential oils. Oral administration of linalool to mice for 6 weeks significantly lowered total and low-density lipoprotein cholesterol concentrations, and HMG-CoA reductase protein expression (-46%; P<0.05) by both transcriptional and posttranscriptional mechanisms. Linalool suppressed the gene expression of HMG-CoA reductase by reducing the binding of SREBP-2 to its promoter, as assessed by qPCR and chromatin immunoprecipitation, and by inducing ubiquitin-dependent proteolysis of the HMG-CoA reductase. These findings suggest that food molecules with a pleasant scent could exert beneficial metabolic effects through multiple mechanisms.

Polyunsaturated fatty acids reduce fatty acid synthase and hydroxy-methyl-glutaryl CoA-reductase gene expression and promote apoptosis in HepG2 cell line.

BACKGROUND: n-3 and n-6 polyunsaturated fatty acids (PUFAs) are the two major classes of PUFAs encountered in the diet, and both classes of fatty acids are required for normal human health. Moreover, PUFAs have effects on diverse pathological processes impacting chronic disease, such as cardiovascular and immune disease, neurological disease, and cancer. AIM: To investigate the effects of eicosapentaenoic acid (EPA) and arachidonic acid (ARA) on the proliferation and apoptosis of human hepatoma cell line HepG2 after exposure to increasing concentrations of EPA or ARA for 48 h. Moreover, in the same cells the gene expression of Fatty Acid Synthase (FAS) and 3-Hydroxy-3-Methyl-Glutaryl Coenzyme A Reductase (HMG-CoAR) was also investigated. METHOD: Cell growth and apoptosis were assayed by MTT and ELISA test, respectively after cell exposure to increasing concentrations of EPA and ARA. Reverse-transcription and real-time PCR was used to detect FAS and HMG-CoAR mRNA levels in treated cells. RESULTS: Our findings show that EPA inhibits HepG2 cell growth in a dose-dependent manner, starting from 25 µM (P < 0.01, one-way ANOVA test and Dunnett's post test) and exerts a statistically significant pro-apoptotic effect already at 1 µM of EPA. Higher doses of ARA were need to obtain a statistically significant inhibition of cell proliferation and a pro-apoptotic effect in these cells (100 µM, P < 0.01, one-way ANOVA test and Dunnett's post test). Moreover, a down-regulation of FAS and HMG-CoAR gene expression was observed after EPA and ARA treatment in HepG2 cells, starting at 10 µM (P < 0.05, one-way ANOVA test and Dunnett's post test). CONCLUSION: Our results demonstrate that EPA and ARA inhibit HepG2 cell proliferation and induce apoptosis. The down-regulation of FAS and HMG-CoAR gene expression by EPA and ARA might be one of the mechanisms for the anti-proliferative properties of PUFAs in an in vitro model of hepatocellular carcinoma.

Proinflammatory gene expression and renal lipogenesis are modulated by dietary protein content in obese Zucker fa/fa rats.

Obesity is a risk factor for the development of chronic kidney disease (CKD) and end-stage renal disease. It is not clear whether the adoption of a high-protein diet in obese patients affects renal lipid metabolism or kidney function. Thus the aims of this study were to assess in obese Zuckerfa/fa rats the effects of different types and amounts of dietary protein on the expression of lipogenic and inflammatory genes, as well as renal lipid concentration and biochemical parameters of kidney function. Rats were fed different concentrations of soy protein or casein (20, 30, 45%) for 2 mo. Independent of the type of protein ingested, higher dietary protein intake led to higher serum triglycerides (TG) than rats fed adequate concentrations of protein. Additionally, the soy protein diet significantly increased serum TG compared with the casein diet. However, rats fed soy protein had significantly decreased serum cholesterol concentrations compared with those fed a casein diet. No significant differences in renal TG and cholesterol concentrations were observed between rats fed with either protein diets. Renal expression of sterol-regulatory element binding protein 2 (SREBP-2) and its target gene HMG-CoA reductase was significantly increased as the concentration of dietary protein increased. The highest protein diets were associated with greater expression of proinflammatory cytokines in the kidney, independent of the type of dietary protein. These results indicate that high soy or casein protein diets upregulate the expression of lipogenic and proinflammatory genes in the kidney.

A novel role for thyroid-stimulating hormone: up-regulation of hepatic 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase expression through the cyclic adenosine monophosphate/protein kinase A/cyclic adenosine monophosphate-responsive element binding protein pathway.

Elevated thyroid-stimulating hormone (TSH) and hypercholesterolemia commonly coexist, as typically seen in hypothyroidism, but there is no known mechanism directly linking the two. Here, we demonstrated that in liver cells, TSH promoted the expression of 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMGCR), a rate-limiting enzyme in cholesterol synthesis, by acting on the TSH receptor in hepatocyte membranes and stimulating the cyclic adenosine monophosphate / protein kinase A / cyclic adenosine monophosphate-responsive element binding protein (cAMP/PKA/CREB) signaling system. In thyroidectomized rats, the production of endogenous thyroid hormone was eliminated and endogenous TSH was suppressed through pituitary suppression with constant administration of exogenous thyroid hormone, and hepatic HMGCR expression was increased by administration of exogenous TSH. These results suggested that TSH could up-regulate hepatic HMGCR expression, which indicated a potential mechanism for hypercholesterolemia involving direct action of TSH on the liver.