MiR-15b can target insulin receptor to regulate hepatic insulin signaling in mice.

Now diabetes is growing to be a health problems globally. However, its specific pathogenesis still needs further exploration. Here we showed that miR-15b was upregulated in the palmitate-induced HepG2 cells and livers of hyperglycemic mice. At the same time, we confirmed that the insulin receptor was a direct target of miR-15b. Then we found that the manipulation of miR-15b expression level could affect the insulin signaling pathway of HepG2 cells and the inhibition of miR-15b in liver of ob/ob mice can improve insulin sensitivity of mice. Furthermore, our study demonstrated that palmitate could upregulate the expression of miR-15b by activating PPARα. Our findings established PPARα-responsive miR-15b as a critical regulator of hepatic insulin signaling, thus serving as a new potential therapeutic target for diabetes.

Hepatic miR­215 target Rictor and modulation of hepatic insulin signalling in rats.

Increasing evidence has suggested that hepatic lipid accumulation is associated with hepatic insulin resistance; however, the underlying mechanism is yet to be determined. It was demonstrated that the levels of microRNA­215 (miR­215) expression in the liver of rats fed a high­fat diet were significantly increased compared with rats on a control diet. Additionally, it was revealed via luciferase assays and western blotting that miR­215 targets rapamycin­insensitive companion of mammalian target of rapamycin (Rictor), an important protein in the hepatic insulin signalling pathway. Following overexpression of miR­215 in the H4IIE rat hepatocarcinoma cell line, it was reported that the intracellular insulin signalling pathway was inhibited; conversely, inhibition of miR­215 expression induced this pathway. Furthermore, it was demonstrated via reverse transcription­quantitative polymerase chain reaction analysis that free fatty acids promoted the expression of miR­215. The present study provided a novel mechanistic insight into the association between nonalcoholic fatty liver and hepatic insulin resistance.

Small interfering RNA targeting receptor for advanced glycation end products suppresses the generation of proinflammatory cytokines.

The aim of the present study was to investigate the effect of receptor for advanced glycation end products (RAGE)-specific small interfering (si)RNA on the generation of proinflammatory cytokines in primary rat hepatic stellate cells (HSCs) and hepatic fibrotic (HF) rats. The RAGE-specific siRNA expression vector pAKD-GR126 was constructed, and then transfected into primary rat HSCs. Reverse transcription-quantitative polymerase chain reaction and western blot analyses were conducted to determine the mRNA and protein expression levels, respectively, of RAGE, tumor necrosis factor (TNF)-α and interleukin (IL)-6 in the primary HSCs. In addition, a CCl4-induced Sprague Dawley (SD) rat model of hepatic fibrosis was established, and pAKD-GR126 was injected into the SD rats via the tail vein. Serum TNF-α and IL-6 concentrations were determined using radioimmunoassay. The mRNA and protein expression levels of RAGE (mRNA, F=7.791; protein, F=36.513), TNF-α (mRNA, F=474.568; protein, F=123.500) and IL-6 (mRNA, F=203.463; protein, F=320.555) in the pAKD-GR126-transfected primary HSCs were significantly reduced compared with those in the control and pAKD-NC groups (P<0.05). Serum TNF-α and IL-6 levels in the low-, medium- and high-dose pAKD-GR126 treatment groups were reduced compared with those in the fibrotic model group (TNF-α, F=416.397; IL-6, F=1,716.659; P<0.05). In summary, the RAGE-specific siRNA was able to effectively suppress the generation of the proinflammatory cytokines TNF-α and IL-6 in primary rat HSCs and HF rats.

Comparison of effects of obesity and non-alcoholic fatty liver disease on incidence of type 2 diabetes mellitus.

AIM: To compare and analyze the effects of obesity and non-alcoholic fatty liver disease (NAFLD) on the incidence of type 2 diabetes mellitus (T2DM) in Chinese subjects. METHODS: In 2008, a population of 4847 subjects was randomly sampled from 17 medical units for enrollment in this cohort study. Baseline information was obtained via a questionnaire on general information, physical examination (height, weight, and blood pressure), laboratory tests (triglycerides, total cholesterol, fasting blood glucose, alanine aminotransferase (ALT), uric acid, and creatinine), B-mode ultrasound, and ECG screening. The incidence of T2DM after four years of follow-up was calculated. Numeric variable data was tested for normality, with the data expressed as mean ± SD. Kaplan-Meier analysis was performed to calculate the cumulative incidence. The Cox proportional hazards model was used to analyze the relative risk (RR) of different body mass index (BMI) levels and NAFLD on T2DM, as well as analyzing the RR adjusted for age, sex, blood pressure, lipids, transaminases, uric acid, and creatinine. RESULTS: A total of 4736 (97.71%) subjects completed 4-year follow-up, with a median follow-up time of 3.85 years, totaling 17223 person-years. 380 subjects were diagnosed with T2DM, with a cumulative incidence of 8.0%. The cumulative incidence of T2DM in the NAFLD and control groups was 17.4% vs 4.1% (P < 0.001), respectively, while the incidence in overweight and obese subjects was 11.0% vs 15.8% (P < 0.001), respectively. The incidence of T2DM increased with an increase in baseline BMI. Cox regression analysis showed that the risk of T2DM in the NAFLD group (RR = 4.492, 95%CI: 3.640-5.542) after adjustment for age, sex, blood pressure, lipids, ALT, uric acid, and creatinine was 3.367 (2.367-4.266), while the value (RR, 95%CI) in overweight and obese subjects after adjustment for age, sex, BMI, blood pressure, lipids and other factors was 1.274 (0.997-1.629) and 1.554 (1.140-2.091), respectively. Stratification of three BMI levels (BMI < 24 kg/m(2), 24 kg/m(2) ≤ BMI < 28 kg/m(2), BMI ≥ 28 kg/m(2)) showed that the risk of T2DM in the NAFLD group was significantly higher than that in the control group (RR = 3.860, 4.049 and 3.823, respectively). CONCLUSION: Compared with BMI, NAFLD could be better at forecasting the risk of T2DM in Chinese subjects, and may be a high risk factor for T2DM, independent of overweight/obesity.

Biological effects of lentivirus-mediated silencing of minichromosome maintenance protein 7 with shRNA on the liver cancer MHCC-97H cells.

OBJECTIVE: This study was to specifically silence the minichromosome maintenance protein 7 (MCM7) expressions with lentivirus-mediated RNA interference technique in liver cancer MHCC-97H cells and its biological consequences were investigated. METHODS: Human MCM7 sequence was used for the design of shRNA targeting MCM7 which was then introduced to lentivirus, followed by transfection into MHCC-97H cells. Real time quantitative PCR and Western blot assay were performed to detect the mRNA and protein expression of MCM7 in these cells. MTT assay was performed to detect cell proliferation, flow cytometry to detect cell cycle and apoptosis, scratch-wound assay to detect cell migration ability, and transwell invasion assay to evaluate the invasion of these cells. RESULTS: We successfully constructed LV-mcm7-RNAi expressing MCM7 shRNA. PCR and Western blot assay showed the mRNA and protein expression of MCM7 reduced significantly when compared with negative control group (LV-NC-RNAi) and blank control group (P<0.05). As compared to blank control group and negative control group, the cell proliferation reduced dramatically (P<0.01), cells were mainly arrested in G0/G1 phase and apoptotic cells increased markedly in LV-mcm7-RNAi group. Moreover, cells transfected with LV-mcm7-RNAi showed significant reductions in the invasion and migration as compared to other groups (P<0.05). CONCLUSION: Lentivirus mediated silencing of MCM7 with shRNA in MHCC-97H cells may inhibit the malignant behaviors of MHCC-97H cells (suppressed proliferation and compromised invasiveness), which is related to the cell cycle arrest and increase in apoptosis.

Inhibitory effect of receptor for advanced glycation end product­specific small interfering RNAs on the development of hepatic fibrosis in primary rat hepatic stellate cells.

Specific small interfering RNAs (siRNAs) targeting receptor for advanced glycation end products (RAGE) inhibit the expression of RAGE, α-smooth muscle actin and type I collagen in the T6 hepatic stellate cells (HSCs), indicating that RAGE is important for the activation of HSCs and the expression of collagen. The present study aimed to investigate the effect of specific siRNAs targeting RAGE on the development of hepatic fibrosis (HF), using primary rat HSCs, which were isolated and cultured in vitro. The expression vectors for specific siRNAs targeting RAGE were constructed and transfected into primary rat HSCs. Untreated and nonspecific siRNA-transfected primary rat HSCs served as controls. The expression levels of RAGE, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), transforming growth factor-ß1 (TGF-ß1), connective tissue growth factor (CTGF), laminin (LN), hyaluronic acid (HA) and N-terminal procollagen III propeptide (PIIINP) in primary HSCs were detected by reverse transcription quantitative polymerase chain reaction and western blotting. The mRNA and 42 kD protein expression of RAGE in the pAKD-GR126-transfected primary HSCs were significantly downregulated compared with those in the untreated and the pAKD-negative control (NC)-transfected controls. The mRNA and protein expression levels of IL-6, TNF-α, TGF-ß1, CTGF, LN, HA and PIIINP in the pAKD-GR126-transfected primary HSCs were also markedly downregulated compared with those in the untreated and pAKD-NC-transfected controls. Therefore, RAGE-specific siRNAs inhibited the expression of RAGE in primary rat HSCs and inhibited the development of HF.

Anti-fibrotic effects of specific-siRNA targeting of the receptor for advanced glycation end products in a rat model of experimental hepatic fibrosis.

Since the receptor for advanced glycation end products (RAGE)-ligand axis has been demonstrated to be important in fibrogenesis, rat models may be used to assess whether specific small interfering RNAs (siRNAs) that target RAGE are able to reduce the progression of hepatic fibrosis. However, the effect of RAGE-targeted siRNA on established hepatic fibrosis remains to be elucidated. In the present study, RAGE-specific siRNA expression vectors were constructed prior to the animal experiment. Sprague-Dawley rats were treated initially with olive oil (2 ml/kg) or 50% CCl4 (2 ml/kg; CCl4/olive oil=1:1) twice per week for six weeks to generate the fibrosis model. The rats were then treated with phosphate­buffered saline, a RAGE-specific siRNA expression vector, at different doses or a non-specific siRNA expression vector twice weekly via tail vein injection for up to six weeks, and were sacrificed at week two, four or six. Compared with the control groups, RAGE­specific siRNA therapy significantly decreased RAGE mRNA and protein expression in rat livers (P<0.01). Following six weeks of RAGE gene-silencing treatment, the liver function, which was assessed by analyzing serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and total bilirubin (TBIL), improved to varying degrees (P<0.01). The expression of nuclear factor-κB (NF-κB) significantly decreased following RAGE gene­silencing therapy (P<0.01). In addition, the serum levels of inflammatory cytokines, including tumor necrosis factor­α (TNF-α) and interleukin-6 (IL-6), and extracellular matrix (ECM) components, including hyaluronic acid (HA), laminin (LN) and procollagen type III (PCIII) also decreased (P<0.01). Furthermore, the expression of α-smooth muscle actin (α-SMA) and collagen I, which indicate the activation of hepatic stellate cells (HSCs), were downregulated following RAGE gene-silencing therapy (P<0.01). Furthermore, the inflammatory activity grade and fibrosis stage of rat livers also significantly improved compared with the control groups following RAGE gene-silencing therapy. Specific targeting of RAGE using siRNA may inhibit RAGE gene expression effectively in the rat hepatic fibrosis model and attenuate the progression of established hepatic fibrosis. This therapeutic effect may be mediated via inhibition of the expression of NF-κB. These findings suggest that RAGE may be a new target to prevent hepatic fibrosis.

MYH rs3219476 and rs3219472 polymorphisms and risk of cholangiocarcinoma.

Cholangiocarcinoma (CCA) is a rare but devastating malignancy. Up to 90% of patients presenting with CCA have no identifiable risk factors. The base excision repair (BER) pathway has a principal role in the repair of mutations caused by oxidized or reduced bases. The MutY homolog (MUTYH, MYH) is one of the key proteins in the BER pathway, but the role of MYH in the tumorigenesis of CCA is largely unknown. In this study, we investigated the influence of MYH rs3219476 and rs3219472 polymorphisms on CCA incidence. MYH genotypes were detected using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. We found that for rs3219472, compared with subjects carrying the MYH G/G genotype, those with the A/A genotype had a 2.816-fold higher risk of CCA [odds ratio (OR)=2.816, 95% confidence interval (CI)=0.992-7.999, P=0.047). For rs3219476, compared with subjects carrying the MYH T/T genotype, those with the T/G genotype had a reduced risk of CCA (OR=0.359, 95% CI=0.17-0.758, P=0.006). Our findings suggest that since significantly increased CCA risk was found in individuals with a homozygous variant genotype for rs3219472, it may be a biomarker for screening individuals at high risk of developing the disease.

Specific siRNA targeting the receptor for advanced glycation end products inhibits experimental hepatic fibrosis in rats.

Receptor for advanced glycation end products (RAGE) was studied in different stages of carbon tetrachloride induced hepatic fibrosis (HF), and effect of its gene silencing in the HF development was evaluated in rats. Silencing RAGE expression by specific siRNA effectively suppressed NF-kappaB activity, hepatic stellate cell activation, and accumulation of extracellular matrix proteins in the fibrotic liver, and also greatly improved the histopathology and the ultrastructure of liver cells. These effects may be partially mediated by the inhibition on IkappaBalpha degradation. RAGE gene silencing effectively prevented liver from fibrosis, therefore it offers a potential pharmacological tool for anti-HF gene therapy.