Project description:AIM:Human cytochrome P-450 2E1 (CYP2E1) takes part in the biotransformation of ethanol, acetone, many small-molecule substrates and volatile anesthetics. CYP2E1 is involved in chemical activation of many carcinogens, procarcinogens, and toxicants. To assess the metabolic and toxicological characteristics of CYP2E1, we cloned CYP2E1 cDNA and established a HepG2 cell line stably expressing recombinant CYP 2E1. METHODS:Human CYP2E1 cDNA was amplified with reverse transcription-polymerase chain reaction (RT-PCR) from total RNAs extracted from human liver and cloned into pGEM-T vector. The cDNA segment was identified by DNA sequencing and subcloned into a mammalian expression vector pREP9. A transgenic cell line was established by transfecting the recombinant plasmid of pREP9-CYP2E1 to HepG2 cells. The expression of CYP2E1 mRNA was validated by RT-PCR. The enzyme activity of CYP2E1 catalyzing oxidation of 4-nitrophenol in postmitochondrial supernate (S9) fraction of the cells was determined by spectrophotometry. The metabolic activation of HepG2-CYP2E1 cells was assayed by N-nitrosodiethylamine (NDEA) cytotoxicity and micronucleus test. RESULTS:The cloned CYP2E1 cDNA segment was identical to that reported by Umeno et al (GenBank access No. J02843). HepG2-CYP2E1 cells expressed CYP2E1 mRNA and had 4-nitrophenol hydroxylase activity (0.162 +/- 0.025 nmol.min(-1).mg(-1) S9 protein), which were undetectable in parent HepG2 cells. HepG2-CYP2E1 cells increased the cytotoxicity and micronucleus rate of NDEA in comparison with those of HepG2 cells. CONCLUSION:The cDNA of human CYP2E1 can be successfully cloned, and a cell line, HepG2-CYP2E1, which can efficiently express mRNA and has CYP2E1 activity, is established. The cell line is useful for testing the cytotoxicity, mutagenicity and metabolism of xenobiotics, which may possibly be activated or metabolized by CYP2E1.
Project description:BackgroundTo determine the antiproliferative effect of gamma-tocotrienol (GTT) treatment on differential protein expression in HepG2 cells.MethodsHepG2 cells were treated with 70 μM GTT for 48 hours and differentially expressed protein spots were determined by two-dimensional electrophoresis (2DE), identified by MALDI-TOF mass spectrometer (MS) and validated by quantitative real-time polymerase chain reaction (qRT-PCR).ResultsGTT treatment on HepG2 cells showed a total of five differentially expressed proteins when compared to their respective untreated cells where three proteins were down-regulated and two proteins were up-regulated. One of these upregulated proteins was identified as peroxiredoxin-4 (Prx4). Validation by qRT-PCR however showed decreased expression of Prx4 mRNA in HepG2 cells following GTT treatment.ConclusionsGTT might directly influence the expression dynamics of peroxiredoxin-4 to control proliferation in liver cancer.
Project description:Optimization of critical factors affects transduction efficiency and is able to reduce reagent consumption. The present study aimed to determine the optimum transduction conditions of small hairpin (sh)RNA against peroxiredoxin 4 (PRDX4) in the HepG2 cell line. Cell viability assays were conducted based on serum condition, incubation time, polybrene concentration and antibiotic dose selection. Non-targeting control shRNA was transduced into HepG2 cells in a 5-fold serial dilution, and colonies positive for green fluorescent protein were counted using ImageJ software. Reverse transcription-quantitative polymerase chain reaction and western blot analysis were performed to validate PRDX4 expression. The optimum cell density for transduction was 5.0×103 cells/well in 96-well plates to achieve 40 to 50% confluency the following day. The transduction media consisted of 10% fetal bovine serum (FBS) and 12 µg/ml polybrene, and was used to dilute lentiviral particles at a functional titer of 4.9×105 TU/ml for multiplicity of infection (MOI) of 20, 15 and 10, for 24 h of incubation. Selection with 7 µg/ml puromycin was performed in transduced cells. shRNA 3 was revealed to inhibit PRDX4 mRNA and protein expression. In conclusion, PRDX4 was successfully silenced in 5.0×103 HepG2 cells cultured with 10% FBS and 12 µg/ml polybrene, at a 4.9×105 TU/ml functional titer for MOI of 20, 15 and 10.
Project description:BackgroundHepatocellular carcinoma (HCC) is a highly invasive disease with a high mortality rate. Our previous study found that Chenodeoxycholic acid (CDCA) as an endogenous metabolite can enhance the anti-tumor effect. Sorafenib has limited overall efficacy as a first-line agent in HCC, and combined with CDCA may improve its efficacy.MethodsHepG2 cells and Balb/c nude mice were used respectively for in vitro and in vivo experiments. Flow cytometry, Western blotting, HE and immunohistochemical staining and immunofluorescence were used to study the effects of CDCA combined with sorafenib on HepG2 cell growth and apoptosis-related proteins. Magnetic bead coupling, protein profiling and magnetic bead immunoprecipitation were used to find the targets of CDCA action. The effect of CDCA on EGFR/Stat3 signaling pathway was further verified by knocking down Stat3 and EGFR. Finally, fluorescence confocal, and molecular docking were used to study the binding site of CDCA to EGFR.ResultsIn this study, we found that CDCA enhanced the effect of sorafenib in inhibiting the proliferation, migration and invasion of HepG2 cells. Magnetic bead immunoprecipitation and protein profiling revealed that CDCA may enhance the effect of sorafenib by affecting the EGFR/Stat3 signaling pathway. Further results from in vitro and in vivo gene knockdown experiments, confocal experiments and molecular docking showed that CDCA enhances the efficacy of sorafenib by binding to the extracellular structural domain of EGFR.ConclusionThis study reveals the mechanism that CDCA enhances the inhibitory effect of sorafenib on HepG2 cell growth in vitro and in vivo, providing a potential new combination strategy for the treatment of HCC.
Project description:Schistosomiasis is a serious but neglected tropical disease, which can cause granulomatous lesions and hepatic fibrosis. The egg-induced liver fibrosis is the primary cause of mortality and morbidity associated with this chronic disease. HPCs are a kind of stem cells with potentially bidirectional differentiation ability and interact with hepatic stellate cells during liver injury. We here reported the activation of HPCs during S. japonicum-induced liver fibrosis. SEA was used to stimulate HPC cell line LE/6 and WB-F344, and the differentiated gene expressions were shown to display the effect. Taken together, our data provides a moelcular framwork for SEA stimulation on HPCs during S. japonicum infection.
Project description:AimTo investigate the effect of NS398 on the metastasis-associated gene expression in LoVo colorectal cancer cells.MethodsLoVo cells were treated with NS398 at the concentration of 100 micromol/L for 24 and 48 h respectively. Total RNA was extracted with TRIzol reagents and reverse transcribed with Superscript II and hybridized with cDNA microarray (containing oncogenes, tumor suppressor genes, signal transduction molecules, adhesive molecules, growth factors, and ESTs) fabricated in our laboratory. After normalization, the ratio of gene expression of NS398 treated to untreated LoVo cells was either 2-fold up or 0.5-fold down was defined as the differentially expressed genes. Semi-quantitative RT-PCR was used to validate the microarray results.ResultsAmong the 447 metastasis-associated genes, 9 genes were upregulated and 8 genes were downregulated in LoVo cells treated with NS398 for 24 h compared to untreated cells. While 31 genes were upregulated and 14 genes were downregulated in LoVo cells treated with NS398 for 48 h. IGFBP-5, PAI-2, JUN, REL, BRCA1, and BRCA2 might be the new targets of NS398 in treatment of colorectal cancer.ConclusionNS398 might exert its anti-metastasis effect on colorectal cancer by affecting several metastasis-associated gene expression.
Project description:BackgroundThe signal transducer and activator of transcription 3 (STAT3) mediates gene expression in response to numerous growth factors and cytokines, playing an important role in many cellular processes. To better understand the molecular mechanisms by which Stat3 influences gene expression in the lung, the effect of pulmonary epithelial cell specific deletion of Stat3 on genome wide mRNA expression profiling was assessed. Differentially expressed genes were identified from Affymetrix Murine GeneChips analysis and subjected to gene ontology classification, promoter analysis, pathway mapping and literature mining.ResultsTotal of 791 mRNAs were significantly increased and 314 mRNAs were decreased in response to the deletion of Stat3Delta/Delta in the lung. STAT is the most enriched cis-elements in the promoter regions of those differentially expressed genes. Deletion of Stat3 induced genes influencing protein metabolism, transport, chemotaxis and apoptosis and decreased the expression of genes mediating lipid synthesis and metabolism. Expression of Srebf1 and 2, genes encoding key regulators of fatty acid and steroid biosynthesis, was decreased in type II cells from the Stat3Delta/Delta mice, consistent with the observation that lung surfactant phospholipids content was decreased. Stat3 influenced both pro- and anti-apoptotic pathways that determine cell death or survival. Akt, a potential transcriptional target of Stat3, was identified as an important participant in Stat3 mediated pathways including Jak-Stat signaling, apoptosis, Mapk signaling, cholesterol and fatty acid biosynthesis.ConclusionDeletion of Stat3 from type II epithelial cells altered the expression of genes regulating diverse cellular processes, including cell growth, apoptosis and lipid metabolism. Pathway analysis indicates that STAT3 regulates cellular homeostasis through a complex regulatory network that likely enhances alveolar epithelial cell survival and surfactant/lipid synthesis, necessary for the protection of the lung during injury.
Project description:The aryl hydrocarbon receptor (AHR) is a ligand-dependent transcription factor. It heterodimerizes with aryl hydrocarbon nuclear translocator, binds to the xenobiotic-responsive element (XRE), and enhances the transcription of genes encoding xenobiotic metabolizing enzymes. AHR also plays important roles in the inhibition of intestinal carcinogenesis and the modulation of gut immunity. It is very important to screen for AHR-activating compounds because those are expected to produce the AHR-mediated physiological functions. Until now, AHR-mediated transcriptional activity represented by the transcriptional activity of CYP1A1 in luciferase assay has been applied as a screening procedure for AHR-activating compounds. However, the AHR-mediated transcriptional activity did not necessarily correspond with the CYP1A1 transcriptional activity. To evaluate AHR-mediated transcriptional activity more specifically, and to screen for AHR-activating compounds, we establish a stable AHR-responsive HepG2 cell line by co-transfection of an AHR expression vector and an AHR-responsive vector (pGL3-XRE) containing a luciferase gene and three tandemly arranged XRE elements into a human hepatoma derived cell line, HepG2. The induction of luciferase activity in the stable AHR-responsive HepG2 cell line by typical AHR activators occurred in time- and concentration-dependent manners. By assessing the AHR target genes CYP1A1, UGT1A1, and ABCG2, an AHR activator-mediated induction was observed at mRNA level. Furthermore, the AHR activator-mediated induction of luciferase activity was positively correlated with the mRNA levels of CYP1A1, UGT1A1, and ABCG2. These findings verified the usefulness of the established stable AHR-responsive HepG2 cell line for the screening of AHR-activating compounds.