Association between miR-146aG>C and miR-196a2C>T polymorphisms and the risk of hepatocellular carcinoma in a Chinese population.

MicroRNAs have been demonstrated to have a role in susceptibility and prognosis of various types of human cancer. We investigated the association between polymorphisms in miR-146aG>C, miR-196a2C>T, and miR-499A>G and hepatocellular carcinoma (HCC) risk and interaction with HCC and hepatitis B virus (HBV) infection. Two hundred sixty-six cases with HCC and 281 health controls were enrolled in the present study. Genotyping of the miR-146aG>C, miR-196a2C>T, and miR-499A>G genotypes was conducted by duplex polymerase chain reaction with the confronting two-pair primer (PCR-RFLP). Subjects with miR-146a GG and G allele had an increased risk of HCC compared with the homozygote CC genotype. Similarly, HCC patients carrying microRNA (miRNA)-196a2 computed tomography, TT, and T allele significantly decreased the risk of HCC relative to the CC genotype. Stratified analysis indicated that miR-196a2C>T polymorphism was associated with reduced risk of HBV-related HCC, but not in hepatitis C virus- and nonviral-related HCC cases. In conclusion, miR-146aG>C and miR-196a2C>T polymorphism are associated with risk of HCC patients in China, especially in patients with HBV infection. SNPs in miRNA sequences can be used as a diagnostic biomarker for HCC.

Associations between three common MicroRNA polymorphisms and hepatocellular carcinoma risk in Chinese.

AIM: Associations between polymorphisms in miR-146aG>C, miR-196a2C>T and miR-499A>G and risk of HCC, and interaction with HBV infection in a Chinese population, were the target of the present research. METHODS: The duplex polymerase-chain-reaction with confronting-two-pair primers (PCR-RFLP) was performed to determine the genotypes of the miR-146aG>C, miR-196a2C>T and miR-499A>G genotypes. Associations of polymorphisms with the risk of HCC were estimated by conditional logistic regression analysis. RESULTS: Drinking, family history of cancer, HBsAg and HCV were risk factors for HCC. Multivariate regression analyses showed that subjects carrying the miR-196a2 CC genotype had significantly increased risk of HCC, with an adjusted OR (95% CI) of 2.18 (1.23-3.80). In addition, cases carrying the miR-196a2 C allele had a 1.64-fold increase in the risk for HCC (95%CI=1.03-2.49). The miR-196a CT and TT genotypes greatly significantly increased the risk of HCC in subjects with HBV infection, with adjusted ORs (95% CI) of 2.02 (1.12-3.68) and 2.69 (1.28-5.71), respectively. CONCLUSION: Our results demonstrate that miR-196a2 CC genotype and C allele have an important role in HCC risk in Chinese, especially in patients with HBV infection.

[Effects of antihistamine treatment on immune function in rats with experimental hepatitis].

OBJECTIVE: To investigate the effects of antihistamine treatment on immune function in rats with experimental hepatitis. METHODS: Thirty Wistar rats were randomly allocated into three groups:experimental hepatitis group (EH group), antihistamine treatment group (AH group) and normal control group (NC group). Rats in the EH group received the subcutaneous injection of 40% carbon tetrachloride oil solution and were fed on diet with low-protein, low-choline, high-fat and high-alcohol,while rats in the AH group received antihistamine treatment(ketotifen + vitamin C) additionally.They were sacrificed after 4 weeks, and the levels of serum alanine aminotransferase(ALT), total bilirubin (TBil), histamine(HA), IFNgamma, IL-12, IL-4 and IL-10 were determined. The levels of IL-12 mRNA and IFN-gamma mRNA in liver tissue were determined via real-time reverse transcriptional polymerase chain reaction(RT-PCR). RESULTS: (1) Compared to the NC group, in the EH group, the levels of ALT, TBil, and circulating and intrahepatic HA were significantly increased(P less than 0.05); intrahepatic HA were significantly decreased(P less than 0.05) after antihistamine treatment. (2) Compared to the NC group, in the EH group, the levels of IL-4, IL-10 were significantly increased((0.504+/-0.202)ng/ml and (29.025+/-1.478) pg/ml vs (0.811+/-0.244)ng/ml and (33.72+/-4.293)pg/ml respectively, P less than 0.05), and the levels of IL-12 were decreased ((6.515+/-2.893)pg/ml vs (3.519+/-1.113)pg/ml, P less than 0.05); and after antihistamine treatment the levels of IL-4 and IL-10 were significantly decreased (were (0.423+/-0.168)ng/ml and (30.412+/-3.275)pg/ml, P less than 0.05), the levels of IL-12 were significantly increased (P less than 0.05), but the level of IFNgamma had no significance (P more than 0.05). The levels of intrahepatic IL-12 mRNA and IFNgamma mRNA had similar results. CONCLUSION: Antihistamine treatment may improve liver function and correct Th1/Th2 unbalance.

[Changes in mast cells and hepatic expression of c-kit and stem cell factor in the rat model of chronic hepatitis].

OBJECTIVE: To study the potential role of mast cells and the related molecular mechanism in chronic hepatitis (CH) using a rat model system. METHODS: Thirty Wistar rats (15 males, 15 females; weight range: 230-290 g) were randomly divided into the normal contrast (NC) group and experimental CH group. The CH group received subcutaneous injection of CCl4 and a diet high in cholesterol and alcohol content and low in protein and choline content. Throughout the 4-week modeling period, aseptic blood samples were taken to test plasma tryptase (TS) and hyaluronic acid (HA) levels. The rats were euthanized to assess the changes in liver mast cells by histology and morphology analyses and the changes in liver expression of c-kit and stem cell factor (SCF) proteins by immunohistochemistry and mRNAs by RT-PCR. RESULTS: Compared to the NC group, the CH group had higher plasma and liver concentration of HA (78.09 +/- 38.55 vs. 145.14 +/- 52.54 ng/ml, 51.58 +/- 20.45 vs. 106.59 +/- 43.15 ng/100 mg; t = 2.457 and 2.825 respectively, both P less than 0.05) and TS (0.416 +/- 0.143 vs 0.753 +/- 0.210 mg/ml; t = 4.165, P less than 0.05). The CH group also showed fatty degeneration and fibrosis with many degranulating and degranulated mast cells filled with purple granula located around the liver blood vessels and in fiber-intervals. The CH livers also showed a significantly higher number of mast cells (2.167 +/- 0.924 vs. NC: 10.92 +/- 1.575; t = 7.633, P less than 0.05) and stronger intensity of c-kit staining (2.783 +/- 0.577 vs. 12.86 +/- 3.126; t = 9.511, P less than 0.05) and SCF staining (3.383 +/- 1.583 vs. 15.58 +/- 6.431; t = 9.625, P less than 0.05). The expressions of c-kit and SCF were positively correlated with HA level (r = 0.478 and 0.556 respectively, both P less than 0.05). The c-kit and SCF mRNA expression levels were also significantly higher in the CH liver tissues. CONCLUSION: Mast cell degranulation and histamine release is significantly increased under conditions of chronic hepatitis, and the related mechanism may involve up-regulation of the membrane receptor c-kit and its ligand SCF.

[Effects of PPAR-alpha activation on oleic acid-induced steatosis and expression of heme oxygenase-1 in HepG2 cells].

OBJECTIVE: To investigate the effects of peroxisome proliferator activated receptor-alpha (PPAR-a) activation on oleic acid (OA)-induced steatosis and hepatic expression of heme oxygenase-1 (HO-1) using an in vitro cell model system. METHODS: A steatosis human hepatocyte in vitro model system was established by treating HepG2 cells with 0.2 mmol/L of oleic acid for 24 hours. The steatosis cells were then divided into four groups for an additional 24 hours of treatment with 0.2 mmol/L of oleic acid alone (model control group) or with 5, 10 or 50 pnol/L of fenofibrate (FF, a selective PPAR-a agonist; experimental groups). Untreated HepG2 cells served as non-steatosis controls. Effect of PPAR-a activation on fat accumulation was detected by Oil Red O staining and on intracellular triglyceride (TG) levels by enzymatic assay. mRNA and protein expression of PPAR-alpha and HO-1 were quantified by real-time PCR and immunocytochemistry, respectively. One-way ANOVA and the LSD t-test were used for between-group comparisons, and correlation analysis was performed with the Pearson's correlation coefficient. RESULTS: The steatosis model control cells showed significantly increased TG deposition (379.98 +/- 23.19 mg/g protein, vs. non-steatosis controls F = 148.56, P< 0.01), significantly decreased mRNA and protein expression of PPAR-alpha (0.42 +/- 0.38,F= 177.64,P< 0.01 and 0.47 +/- 0.14, F= 120.76,P< 0.01) and HO-1 (0.36 +/- 0.66, F= 74.77,P< 0.01 and 0.26 +/- 0.10,F= 119.90,P<0.01). FF (5, 10 and 50 micromol/L) inhibited the steatosis induced by OA in a concentration-dependent manner (294.00 +/- 19.80, 250.33 +/- 9.96, and 196.99 +/- 9.14, F = 148.56, P <0.01) and increased the mRNA and protein expression of PPAR-alpha (0.55 +/- 0.65, 0.85 +/- 0.61, and 1.31 +/- 0.36,F= 177.64,P< 0.01; 0.82 + 0.11, 1.31 +/- 0.16, and 1.75 +/- 0.13, F= 120.76,P <0.01) and HO-1 (0.62 +/- 0.05, 0.84 +/- 0.07, and 1.30 +/- 0.11,F= 74.77,P <0.01; 0.44 +/- 0.08, 0.81 +/- 0.08, 1.20 +/- 0.10,F= 119.90,P< 0.01). CONCLUSION: Activation of PPAR-a prevents OA-induced steatosis in HepG2 cells, and HO-1 may function as a downstream effector of this mechanism.

[Effect of reduced glutathione on proliferation of rat hepatic stellate cells and the Nrf2/HO-1 signaling pathway].

OBJECTIVE: To explore the effects of reduced glutathione (GSH) on the proliferation of hepatic stellate cells and the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway. METHODS: The rat HSC-T6 cell line was activated by lipopolysaccharide (LPS; 0.1 mug/ml) and incubated with various concentrations of GSH (0, 1, 2, 5 and 10 mmol/L) for 24 h. Cell proliferation was evaluated by the MTT colorimetric assay. Collagen IV and hyaluronic acid (HA) contents were measured by chemiluminescence immunoassay of cell supernatants. Nrf2 and HO-1 protein expression was observed by immunohistochemistry. Nrf2 and HO-1 mRNA expression was assessed by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). HO-1 activity was analyzed by spectrophotometer. RESULTS: GSH treatment inhibited HSC-T6 proliferation and decreased the secretion of HA and collagen IV (P less than 0.05); GSH treatment of HSC-T6 cells also led to increased expression of Nrf2 and HO-1, and increased activity of HO-1 (P less than 0.05). CONCLUSION: GSH can inhibit the proliferation of hepatic stellate cells in vitro and reduce secretion of hyaluronic acid and collagen IV. The underlying mechanism in HSC-T6 cells may involve regulation of the Nrf2/HO-1 signaling pathway.

[Protein expression and function of gene 2 transregulated by hepatitis B virus pre-s1 protein and its cloning].

OBJECTIVE: To screen proteins in leukocytes interacting with PS1TP2 by yeast-two hybrid and to view their subcellular localization in HepG2 cells. METHODS: The function and structure of PS1TP2 were studied by bioinformatic analysis. PS1TP2 gene was amplified and cloned into plasmid pET32a (+) and pGBKT7 to construct recombinant expression vectors pET32a (+)-PS1TP2 and pGBKT7-PS1TP2. They were transduced into E. coli Rosetta strain and yeast AH109. The transformed yeast mated with yeast Y187 containing leukocyte cDNA library plasmid in a 2xYPDA medium. Diploid yeast cells were plated on a synthetic dropout nutrient medium (SD/-Trp-Leu-His-Ade) for selecting twice and then screening. Then a green fluorescent protein (GFP) expression vector pEGFP-C1-PS1TP2 was established, transduced into HepG2, and its subcellular localization was studied by fluorescence microscopy and confocal microscopy. RESULTS: Bioinformatic analysis showed that the PS1TP2 gene was located at 6q24.1, the protein was unstable and the aliphatic index was very high. After transformation of the E. coli and yeast AH109, the expression protein showed: (1) the molecular weight of the expressed product was about 41000 Da, and (2) PS1TP2 existed within the cells. Diploid yeast cells were plated on the synthetic dropout nutrient medium containing X-a-gal for selecting twice and then screening. Twenty-six colonies from blue colonies were sequenced, pEGFP-C1-PS1TP2 was successfully expressed in the HepG2 cells, and PS1TP2 was located in the cell plasma. CONCLUSION: A prokaryotic expression vector pET32a(+)-PS1TP2 was constructed successfully and the PS1TP2 was successfully expressed in the yeast system. Genes of PS1TP2 interact with leukocyte proteins. These results bring some new clues for studying the biological functions of HBV.

Screening and cloning for proteins transactivated by the PS1TP5 protein of hepatitis B virus: a suppression subtractive hybridization study.

AIM: To clone and identify human genes transactivated by PS1TP5 by constructing a cDNA subtractive library with suppression subtractive hybridization (SSH) technique. METHODS: SSH and bioinformatics techniques were used for screening and cloning of the target genes transactivated by PS1TP5 protein. The mRNA was isolated from HepG2 cells transfected with pcDNA3.1(-)-myc-his(A)-PS1TP5 and pcDNA3.1(-)-myc-his(A) empty vector, respectively, and SSH technique was employed to analyze the differentially expressed DNA sequence between the two groups. After digestion with restriction enzyme Rsa I, small size cDNAs were obtained. Then tester cDNA was divided into two groups and ligated to the specific adaptor 1 and adaptor 2, respectively. The tester cDNA was hybridized with driver cDNA twice and subjected to nested PCR for two times, and then subcloned into T/A plasmid vectors to set up the subtractive library. Amplification of the library was carried out with E. coli strain DH5alpha. The cDNA was sequenced and analyzed in GenBank with Vector NTI 9.1 and NCBI BLAST software after PCR amplification. RESULTS: The subtractive library of genes transactivated by PS1TP5 was constructed successfully. The amplified library contained 90 positive clones. Colony PCR showed that 70 clones contained 200-1000-bp inserts. Sequence analysis was performed in 30 clones randomly, and the full-length sequences were obtained by bioinformatics technique. Altogether 24 coding sequences were obtained, which consisted of 23 known and 1 unknown. One novel gene with unknown functions was found and named as PS1TP5TP1 after being electronically spliced, and deposited in GenBank (accession number: DQ487761). CONCLUSION: PS1TP5 is closely correlated with immunoregulation, carbohydrate metabolism, signal transduction, formation mechanism of hepatic fibrosis, and occurrence and development of tumor. Understanding PS1TP5 transactive proteins may help to bring some new clues for further studying the biological functions of pre-S1 protein.

Screening of genes for proteins interacting with the PS1TP5 protein of hepatitis B virus: probing a human leukocyte cDNA library using the yeast two-hybrid system.

BACKGROUND: The hepatitis B virus (HBV) genome includes S, C, P and X regions. The S region is divided into four subregions of pre-pre-S, pre-S1, pre-S2 and S. PS1TP5 (human gene 5 transactivated by pre-S1 protein of HBV) is a novel target gene transactivated by the pre-S1 protein that has been screened with a suppression subtractive hybridization technique in our laboratory (GenBank accession: AY427953). In order to investigate the biological function of the PS1TP5 protein, we performed a yeast two-hybrid system 3 to screen proteins from a human leukocyte cDNA library interacting with the PS1TP5 protein. METHODS: The reverse transcription polymerase chain reaction (RT-PCR) was performed to amplify the gene of PS1TP5 from the mRNA of HepG2 cells and the gene was then cloned into the pGEM-T vector. After being sequenced and analyzed with Vector NTI 9.1 and NCBI BLAST software, the target gene of PS1TP5 was cut from the pGEM-T vector and cloned into a yeast expression plasmid pGBKT7, then "bait" plasmid pGBKT7-PS1TP5 was transformed into the yeast strain AH109. The yeast protein was isolated and analyzed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting hybridization. After expression of the pGBKT7-PS1TP5 fusion protein in the AH109 yeast strain was accomplished, a yeast two-hybrid screening was performed by mating AH109 with Y187 containing a leukocyte cDNA library plasmid. The mated yeast was plated on quadruple dropout medium and assayed for alpha-gal activity. The interaction between the PS1TP5 protein and the proteins obtained from positive colonies was further confirmed by repeating the yeast two-hybrid screen. After extracting and sequencing of plasmids from blue colonies we carried out a bioinformatic analysis. RESULTS: Forty true positive colonies were selected and sequenced, full length sequences were obtained and we searched for homologous DNA sequences from GenBank. Among the 40 positive colonies, 23 coding genes with known functions were obtained, including Homo sapien leukocyte adhesion protein p150, 95, interleukin 2 receptor gamma chain, PALM2-AKAP2 protein (PALM2-AKAP2), eukaryotic translation initiation factor 4A, beta-2-microglobin, solute carrier family 9 (sodium/hydrogen exchanger), calreticulin, asialoglycoprotein receptor 1 (ASGR1), MHC class II lymphocyte antigen, cytochrome c oxidase subunit 1, lymphocyte antigen 86 (LY86) and lymphocyte cytosolic protein 1. One novel gene with unknown function was found and named as PS1TP5BP1. After being electronically spliced, it was deposited in GenBank (accession number: DQ471327). CONCLUSIONS: Genes of proteins interacting with PS1TP5 were successfully screened from leukocyte cDNA library. These results suggested that PS1TP5 was closely correlated with immunoregulation, carbohydrate metabolism, signal transduction, the formation of hepatic fibrosis and initiation and development of tumors and also brought some new clues for further studying the biological functions of the pre-S1 protein.

Inhibition of hepatitis B virus expression and replication by RNA interference in HepG2.2.15.

AIM: To observe the inhibition of hepatitis B virus replication and expression by transfecting vector-based small interference RNA (siRNA) pGenesil-HBV X targeting HBV X gene region into HepG2.2.15 cells. METHODS: pGenesil-HBV X was constructed and transfected into HepG2.2.15 cells via lipofection. HBV antigen secretion was determined 24, 48, and 72 h after transfection by time-resolved immunofluorometric assays (TRFIA). HBV replication was examined by fluorescence quantitative PCR, and the expression of cytoplasmic viral proteins was determined by immunohistochemistry. RESULTS: The secretion of HBsAg and HBeAg into the supernatant was found to be inhibited by 28.5% and 32.2% (P < 0.01), and by 38.67% (P < 0.05) and 42.86% (P < 0.01) at 48 h and 72 h after pGenesil-HBV X transfection, respectively. Immunohistochemical staining for cytoplasmic HBsAg showed a similar decline in HepG2.2.15 cells 48 h after transfection. The number of HBV genomes within culture supernatants was also significantly decreased 48 h and 72 h post-transfection as quantified by fluorescence PCR (P < 0.05). CONCLUSION: In HepG2.2.15 cells, HBV replication and expression is inhibited by vector-based siRNA pGenesil-HBV X targeting the HBV X coding region.

[Screening and cloning target genes transactivated by hepatitis C virus F protein using suppression subtractive hybridization technique].

OBJECTIVES: To identify and clone human genes transactivated by HCV F protein by constructing a cDNA subtractive library using the suppression subtractive hybridization technique. METHODS: Suppression subtractive hybridization (SSH) and bioinformatics techniques were used for screening and cloning of the target genes transactivated by HCV F protein. The mRNA was isolated from HepG2 cells transfected with pcDNA3.1 (-)-F or with pcDNA3.1(-) empty vector as a control, and SSH method was employed to analyze the differentially expressed DNA sequence between the two groups. After restriction enzyme Rsa I digestion, small sized cDNAs were obtained. Then tester cDNA was divided into two groups and ligated to the specific adaptor 1 or adaptor 2. After tester cDNA was hybridized with driver cDNA twice and underwent two times of nested PCR, it was then subcloned into T/A plasmid vectors to set up the subtractive library. Amplification of the library was carried out with E. coli strain DH5 alpha. The cDNA was sequenced and analyzed in GenBank with blast search after PCR. RESULTS: The subtractive library of genes transactivated by HCV F protein was constructed successfully. The amplified library contains 71 positive clones. Colony PCR shows that 56 clones contain 200-1000 bp inserts. Sequence analysis was performed on 28 clones randomly, and the full length sequences were obtained with using the bioinformatics method. Altogether 19 coding sequences were obtained, consisting of 17 known and 2 unknown. CONCLUSIONS: The obtained sequences may be target genes transactivated by HCV F protein, and some gene coding proteins are those involved in cell cycle regulation, metabolism, and cell apoptosis.

[Effect of Endotoxin on the expression of peroxisome proliferator-activated receptor alpha in the development of nonalcoholic steatohepatitis in rats].

OBJECTIVE: To study the effect of endotoxin on the expression of peroxisome proliferator-activated receptor alpha (PPARa) in the development of nonalcoholic steatohepatitis in rats. METHODS: A model of nonalcoholic steatohepatitis (NASH) was developed with Wistar rats fed a chow containing 20% maize oil for 14 weeks. The endotoxin group rats were intraperitoneally injected with lipopolysaccharide (LPS, 1 g/L, 3.0 ml/kg) once 4 hours before the end of the experiment. The concentrations of lipids, endotoxin, tumor necrosis factor-a, malondialdehyde, free fatty acid in plasma and hepatic tissues were determined and the degree of hepatocytic steatosis was studied. The expression of PPARa mRNA in hepatic tissues was measured using reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: The expression of PPARa mRNA in the hepatic tissue of the LPS group was downregulated markedly in comparison to that of the control group. The level of free fatty acid and endotoxin by secreting tumor necrosis factor-a increased and triglyceride accumulated in the liver caused malondialdehyde content to increase, then lipid peroxidation process enhanced and ALT activity increased. Thus, hepatic injury and inflammatory reaction could be accelerated. CONCLUSION: Endotoxemia can enhance hepatocellular steatosis and lead to NASH due to its downregulating the expression of PPARa mRNA.