Chronic supplementation of proanthocyanidins reduces postprandial lipemia and liver miR-33a and miR-122 levels in a dose-dependent manner in healthy rats

Elevated postprandial triglycerides are associated with an increased risk of cardiovascular disease. Acute proanthocyanidin supplementation improves postprandial lipemia. Therefore, in this study, we evaluated whether a chronic treatment (3 weeks) of grape seed proanthocyanidins (GSPE) improves tolerance to lipid overload and represses liver microRNA (miRNA)-33a and miRNA-122 and their target genes as a mechanism to soften the elevated postprandial triglycerides in healthy rats. Additionally, the minimal GSPE chronic dose required to alter miRNA levels was determined by means of a dose–response experiment using 5, 15, 25 or 50 mg of GSPE/kg body weight. GSPE repressed miR-33a and miR-122 liver expression and reduced postprandial lipemia in a dose-dependent manner. Significant effects were only observed at high levels of proanthocyanidin consumption, but moderate doses of proanthocyanidins were still able to modulate miRNA expression. Therefore, it can be suggested that a population with a normal intake of proanthocyanidin-rich foods can benefit from the modulation of miRNA expression. At the molecular level, this action can confer homeostatic robustness and will thus exert subtle changes in lipid metabolism, thereby reducing the risk associated with postprandial hyperlipemia.     

MicroRNA-590-5p regulates proliferation and invasion in human hepatocellular carcinoma cells by targeting TGF-β RII

MicroRNAs (miRNAs) are regulatory small non-coding RNAs that can regulate gene expression by binding to gene elements, such as the gene promotor 5'UTR, mainly in the 3'UTR of mRNA. One miRNA targets many mRNAs, which can be regulated by many miRNAs, leading to a complex metabolic network. In our study, we found that the expression level of miR-590-5p is higher in the human hepatocellular carcinoma cell line HepG2 than in the normal hepatocellular cell line L02. Downregulation of miR-590-5p inhibited proliferation and invasion of hepatocellular carcinoma cells (HCCs). We also showed that expression of TGF-beta RII, which has been regarded as a regulator of tumor proliferation, invasion, and migration in hepatocellular carcinoma, is regulated by miRNA-590-5p. In addition, miR-590-5p downregulated the expression of TGF-beta RII by targeting the 3'UTR of mRNA. We also found that downregulation of miR-590-5p was associated with an elevation of TGF-beta RII and inhibition of proliferation and invasion in HepG2 cells. Furthermore, overexpression of miR-590-5p was associated with upregulation of TGF-beta RII and could promote proliferation and invasion in L02 cells. In conclusion, we determined that TGF-beta RII is a novel target of miRNA-590-5p. Thus, the role of TGF-beta RII in regulating proliferation and invasion of human HCCs is controlled by miR-590-5p. In other words, miR-590-5p promotes proliferation and invasion in human HCCs by directly targeting TGF-beta RII.     

Serum metabolites of proanthocyanidin-administered rats decrease lipid synthesis in HepG2 cells

The regular consumption of flavonoids has been associated with reduced mortality and a decreased risk of cardiovascular diseases. The proanthocyanidins found in plasma are very different from the original flavonoids in food sources. The use of physiologically appropriate conjugates of proanthocyanidins is essential for the in vitro analysis of flavonoid bioactivity.In this study, the effect of different proanthocyanidin-rich extracts, which were obtained from cocoa (CCX), French maritime pine bark (Pycnogenol extract, PYC) and grape seed (GSPE), on lipid homeostasis was evaluated. Hepatic human cells (HepG2 cells) were treated with 25 mg/L of CCX, PYC or GSPE. We also performed in vitro experiments to assess the effect on lipid synthesis that is induced by the bioactive GSPE proanthocyanidins using the physiological metabolites that are present in the serum of GSPE-administered rats. For this, Wistar rats were administered 1 g/kg of GSPE, and serum was collected after 2 h. The semipurified serum of GSPE-administered rats was fully characterized by liquid chromatography tandem triple quadrupole mass spectrometry (LC–QqQ/MS²). The lipids studied in the analyses were free cholesterol (FC), cholesterol ester (CE) and triglycerides (TG).All three proanthocyanidin-rich extracts induced a remarkable decrease in the de novo lipid synthesis in HepG2 cells. Moreover, GSPE rat serum metabolites reduced the total percentage of CE, FC and particularly TG; this reduction was significantly higher than that observed in the cells directly treated with GSPE. In conclusion, the bioactivity of the physiological metabolites that are present in the serum of rats after their ingestion of a proanthocyanidin-rich extract was demonstrated in Hep G2 cells.     

Upregulation of oxidant-induced VEGF expression in cultured keratinocytes by a grape seed proanthocyanidin extract.

Angiogenesis plays a central role in wound healing. Among many known growth factors, vascular endothelial growth factor (VEGF) is believed to be the most prevalent, efficacious, and long-term signal that is known to stimulate angiogenesis in wounds. The wound site is rich in oxidants such as hydrogen peroxide mostly contributed by neutrophils and macrophages. Proanthocyanidins or condensed tannins are a group of biologically active polyphenolic bioflavonoids that are synthesized by many plants. This study provides first evidence showing that natural extracts such as grape seed proanthocyanidin extract containing 5000 ppm resveratrol (GSPE) facilitates oxidant-induced VEGF expression in keratinocytes. Using a ribonuclease protection assay (RPA), the ability of GSPE to regulate oxidant-induced changes in several angiogenesis-related genes were studied. While mRNA responses were studied using RPA, VEGF protein release from cells to the culture medium was studied using ELISA. Pretreatment of HaCaT keratinocytes with GSPE upregulated both hydrogen peroxide as well as TNF-alpha-induced VEGF expression and release. The current results suggest that GSPE may have beneficial therapeutic effects in promoting dermal wound healing and other related skin disorders.     

Protection of primary glial cells by grape seed proanthocyanidin extract against nitrosative/oxidative stress.

Previous studies showed that proanthocyanidins provide potent protection against oxidative stress. Here we investigate the effects of grape seed proanthocyanidin extract (GSPE) as a novel natural antioxidant on the generation and fate of nitric oxide (NO) in rat primary glial cell cultures. GSPE treatment (50 mg/L) increased NO production (measured by NO(2-) assay) by stimulation of the inducible isoform of NOS. However, GSPE failed to affect the LPS/IFN-gamma-induced NO production or iNOS expression. Similar responses were found in the murine macrophage cell line RAW264.7. GSPE did not show any effect on dihydrodichlorofluorescein fluorescence (ROS marker with high sensitivity toward peroxynitrite) either in control or in LPS/IFN-gamma-induced glial cultures even in the presence of a superoxide generator (PMA). GSPE treatment alone had no effect on the basal glutathione (GSH) status in glial cultures. Whereas the microglial GSH level declined sharply after LPS/IFN-gamma treatment, the endogenous GSH pool was protected when such cultures were treated additionally with GSPE, although NO levels did not change. Glial cultures pretreated with GSPE showed higher tolerance toward application of hydrogen peroxide (H(2)O(2)) and tert-butylhydroperoxide. Furthermore, GSPE-pretreated glial cultures showed improved viability after H(2)O(2)-induced oxidative stress demonstrated by reduction in lactate dehydrogenase release or propidium iodide staining. We showed that, in addition to its antioxidative property, GSPE enhances low-level production of intracellular NO in primary rat astroglial cultures. Furthermore, GSPE pretreatment protects the microglial GSH pool during high output NO production and results in an elevation of the H(2)O(2) tolerance in astroglial cells.     

Aberrant expression of microRNA induced by high-fructose diet: implications in the pathogenesis of hyperlipidemia and hepatic insulin resistance

Fructose is a highly lipogenic sugar that can alter energy metabolism and trigger metabolic disorders. In the current study, microRNAs (miRNAs) altered by a high-fructose diet were comprehensively explored to elucidate their significance in the pathogenesis of chronic metabolic disorders. miRNA expression profiling using small noncoding RNA sequencing revealed that 19 miRNAs were significantly upregulated and 26 were downregulated in the livers of high-fructose-fed mice compared to chow-fed mice. Computational prediction and functional analysis identified 10 miRNAs, miR-19b-3p, miR-101a-3p, miR-30a-5p, miR-223-3p, miR-378a-3p, miR-33-5p, miR-145a-3p, miR-128-3p, miR-125b-5p and miR-582-3p, assembled as a regulatory network to potentially target key genes in lipid and lipoprotein metabolism and insulin signaling at multiple levels. qRT-PCR analysis of their potential target genes [IRS-1, FOXO1, SREBP-1c/2, ChREBP, insulin-induced gene-2 (Insig-2), microsomal triglyceride transfer protein (MTTP) and apolipoprotein B (apoB)] demonstrated that fructose-induced alterations of miRNAs were also reflected in mRNA expression profiles of their target genes. Moreover, the miRNA profile induced by high-fructose diet differed from that induced by high-fat diet, indicating that miRNAs mediate distinct pathogenic mechanisms in dietary-induced metabolic disorders. This study presents a comprehensive analysis of a new set of hepatic miRNAs, which were altered by high-fructose diet and provides novel insights into the interaction between miRNAs and their target genes in the development of metabolic syndrome.     

Regulation of Coagulation Factor XI Expression by MicroRNAs in the Human Liver

High levels of factor XI (FXI) increase the risk of thromboembolic disease. However, the genetic and environmental factors regulating FXI expression are still largely unknown. The aim of our study was to evaluate the regulation of FXI by microRNAs (miRNAs) in the human liver. In silico prediction yielded four miRNA candidates that might regulate FXI expression. HepG2 cells were transfected with miR-181a-5p, miR-23a-3p, miR-16-5p and miR-195-5p. We used mir-494, which was not predicted to bind to F11, as a negative control. Only miR-181a-5p caused a significant decrease both in FXI protein and F11 mRNA levels. In addition, transfection with a miR-181a-5p inhibitor in PLC/PRF/5 hepatic cells increased both the levels of F11 mRNA and extracellular FXI. Luciferase assays in human colon cancer cells deficient for Dicer (HCT-DK) demonstrated a direct interaction between miR-181a-5p and 3′untranslated region of F11. Additionally, F11 mRNA levels were inversely and significantly correlated with miR-181a-5p levels in 114 healthy livers, but not with miR-494. This study demonstrates that FXI expression is directly regulated by a specific miRNA, miR-181a-5p, in the human liver. Future studies are necessary to further investigate the potential consequences of miRNA dysregulation in pathologies involving FXI.     

Interferon-β Induced microRNA-129-5p Down-Regulates HPV-18 E6 and E7 Viral Gene Expression by Targeting SP1 in Cervical Cancer Cells

Infection by human papillomavirus (HPV) can cause cervical intraepithelial neoplasia (CIN) and cancer. Down-regulation of E6 and E7 expression may be responsible for the positive clinical outcomes observed with IFN treatment, but the molecular basis has not been well determined. As miRNAs play an important role in HPV induced cervical carcinogenesis, we hypothesize that IFN-β can regulate the expressions of specific miRNAs in cervical cancer cells, and that these miRNAs can mediate E6 and E7 expression, thus modulate their oncogenic potential. In this study, we found that miR-129-5p to be a candidate IFN-β inducible miRNA. MiR-129-5p levels gradually decrease with the development of cervical intraepithelial lesions. Manipulation of miR-129-5p expression in Hela cells modulates HPV-18 E6 and E7 viral gene expression. Exogenous miR-129-5p inhibits cell proliferation in Hela cells, promotes apoptosis and blocks cell cycle progression in Hela cells. SP1 is a direct target of miR-129-5p in Hela cells. This study is the first report of a cellular miRNA with anti-HPV activity and provides new insights into regulatory mechanisms between the HPV and the IFN system in host cells at the miRNA level.     

人肝脏特异性miR-122表达载体的构建及鉴定

人肝脏特异性miRNA-122是肝脏中表达丰度最高的miRNA。为研究该miR-122的生物学功能,从HepG2细胞基因组中用PCR的方法扩增了miR-122的前体,构建了miR-122的表达载体pLMP-miR-122。pLMP-miR-122质粒转染人正常肝细胞系L-O2和肝癌细胞系HepG2后,细胞内成熟miRNA-122的表达量显著增加。该质粒与HBV1.3共转染HepG2细胞72h后,HBV的HBs和HBe蛋白水平的表达量均下降,说明miRNA-122参与了HBV基因的复制和表达的调控,为进一步研究miRNA-122的功能和其他一些肝病如HCC的调控机制打下基础。     

MicroRNAs 130a/b are regulated by BCR-ABL and downregulate expression of CCN3 in CML

Chronic Myeloid Leukaemia (CML) is a myeloproliferative disorder characterized by the expression of the oncoprotein, Bcr-Abl kinase. CCN3 normally functions as a negative growth regulator, but it is downregulated in CML, the mechanism of which is not known. MicroRNAs (miRNAs) are small non-coding RNAs, which negatively regulate protein translation by binding to the complimentary sequences of the 3′ UTR of messenger RNAs. Deregulated miRNA expression has emerged as a hallmark of cancer. In CML, BCR-ABL upregulates oncogenic miRNAs and downregulates tumour suppressor miRNAs favouring leukaemic transformation. We report here that the downregulation of CCN3 in CML is mediated by BCR-ABL dependent miRNAs. Using the CML cell line K562, we profiled miRNAs, which are BCR-ABL dependent by transfecting K562 cells with anti-BCR-ABL siRNA. MiRNA expression levels were quantified using the Taqman Low Density miRNA array platform. From the miRNA target prediction databases we identified miRNAs that could potentially bind to CCN3 mRNA and reduce expression. Of these, miR-130a, miR-130b, miR-148a, miR-212 and miR-425-5p were significantly reduced on BCR-ABL knockdown, with both miR-130a and miR-130b decreasing the most within 24 h of siRNA treatment. Transfection of mature sequences of miR-130a and miR-130b individually into BCR-ABL negative HL60 cells resulted in a decrease of both CCN3 mRNA and protein. The reduction in CCN3 was greatest with overexpression of miR-130a whereas miR-130b overexpression resulted only in marginal repression of CCN3. This study shows that miRNAs modulate CCN3 expression. Deregulated miRNA expression initiated by BCR-ABL may be one mechanism of downregulating CCN3 whereby leukaemic cells evade negative growth regulation.     

Grape seed proanthocyanidins improves mitochondrial function and reduces oxidative stress through an increase in sirtuin 3 expression in EA.hy926 cells in high glucose condition

Proanthocyanidins are phenolic compounds abundant in the diet, commonly found in grapes and derivatives, foods known for their health-promoting benefits. There is previous evidence showing the antidiabetic activity of proanthocyanidins, however, their mechanisms of action have not been fully elucidated. This study evaluated the capacity of grape seed proanthocyanidins extract (GSPE) to modulate oxidative stress, nitric oxide levels, mitochondrial dysfunction, apoptosis, and sirtuin expression in endothelial cells EA.hy926 under high glucose condition. In addition, the possible toxic effects of GSPE was evaluated in a zebrafish embryos model. The results showed that GSPE was able to enhance cell viability and avoid the disturbance in redox metabolism induced by high glucose. Moreover, GSPE was able to avoid mitochondria dysfunction and the increased in p53 and poly-(ADP-ribose) polymerase expression induced by high glucose exposition. These effects were attributed to the increase in expression of sirtuin 3, a protein able to regulate mitochondrial function. GSPE in an effective concentration did not show toxic effects in zebrafish embryos model. Taken together, these data elucidate the key molecular target of GSPE for future pharmacological interventions in diabetic patients.

Graphic abstract

     

Hsa_circRNA_0088036 acts as a ceRNA to promote bladder cancer progression by sponging miR-140-3p

Circular RNAs (circRNAs) are a class of non-coding RNAs that play vital roles in cancer biology. However, the potential role of hsa_circRNA_0088036 in bladder cancer (BCa) remains unknown. Hsa_circRNA_0088036 was identified by microarray analysis and validated by quantitative real-time polymerase chain reaction. Functional assays were conducted to confirm the effects of hsa_circRNA_0088036 on the growth, migration, invasion, tumorigenesis, and metastasis of BCa cells. The luciferase reporter assay and RNA pull down assay were performed to investigate the interactions between hsa_circRNA_0088036, miR-140-3p, and forkhead box protein Q1 (FOXQ1). Upregulated expression of hsa_circRNA_0088036 in BCa tissues and cell lines was positively correlated with overall survival and clinicopathologic characteristics. Knockdown of hsa_circRNA_0088036 inhibited the growth, migration, and invasion of BCa cells both in vivo and in vitro. Mechanistically, hsa_circRNA_0088036 could directly interact with miR-140-3p and act as a miRNA sponge to modulate FOXQ1 expression. Knockdown of hsa_circRNA_0088036 inhibited the proliferation, migration, and metastasis of BCa cells via miR-140-3p/FOXQ1 signaling, suggesting that hsa_circRNA_0088036 is a potential biomarker and therapeutic target for BCa.Subject terms: Bladder cancer, Long non-coding RNAs     

Circulating miRNA as novel markers for diastolic dysfunction

MicroRNAs (miRNAs) are small noncoding RNAs that negatively regulate gene expression. Though their significance is unclear, pioneer profiling studies have attributed specific serum miRNA signatures to different disease conditions. The diagnostic potential of miRNA detection in human plasma for cardiovascular disorders is beginning to be recognized as important. In this study, we examined miRNA profiling in isolated diastolic dysfunction (DD) with preserved systolic function to identify promising candidate miRNAs. The presence of these miRNAs was tested in stable patients with isolated DD, patients with stable compensated dilated cardiomyopathy (DCM—systolic plus diastolic dysfunction) and those with decompensated congestive heart failure secondary to dilated cardiomyopathy (DCM–CHF—systolic plus diastolic dysfunction). We identified new circulating miRNAs (miR-454, miR-500, miR-1246, miR-142-3p) which showed distinct patterns of expression in patients with diastolic dysfunction. The presence or absence of systolic dysfunction does not seem to affect this trend. MiR-454 and miR-500 are downregulated in diastolic dysfunction. MiR-1246 is upregulated in diastolic dysfunction. MiR-142-3p is downregulated in DCM and DCM–CHF groups but not in the DD group. The expression of miR-124-5p is highly upregulated in DCM but not in DD and DCM–CHF groups. We therefore propose that these circulating miRNAs may serve as novel biomarkers for diastolic dysfunction because in all of these patients the only common factor was diastolic dysfunction.