Simvastatin inhibits the core promoter of the TXNRD1 gene and lowers cellular TrxR activity in HepG2 cells

Catechins and caffeine absorption, and antioxidant activity of tea-macerated wine in a Caco-2 intestinal cell culture model

A novel style of flavored wine was developed via infusion of either black tea or green tea into Chardonnay wine. The bioaccessibility and bioavailability of phenolic substances in green/black tea-infused Chardonnay wine were investigated. Catechin, caffeine, and epicatechin gallate, originating from the tea, displayed high absorption rates with apparent permeability coefficient values above 10 × 10-6 cm/s in a human Caco-2 intestinal cell model. A paracellular pathway was proposed to drive the transport of catechin and epicatechin gallate, while the possible transport pathway of caffeine is passive transcellular diffusion route. Co-supplementation of flavonoids of quercetin or naringenin (20 µM) could further enhance the uptake of catechin and epicatechin gallate, but reduce the absorption of caffeine. Great in vitro and cellular antioxidant capacities were witnessed in the tea-macerated wine samples. The wine samples also neutralized the negative impact of tert-butyl hydroperoxide (25 µM) on glutathione S-transferase and glutathione levels, apoptosis induction, and intracellular malondialdehyde levels. RNA sequencing with limma method revealed a total of 1473 and 406 differentially expressed genes in the 21-day-old Caco-2 intestinal cells treated with the green and black tea-macerated wines for 5 h respectively, indicating metabolic changes in the cells from the different wines.

Patients with Osteoarthritis and Kashin-Beck Disease Display Distinct CpG Methylation Profiles in the DIO2, GPX3, and TXRND1 Promoter Regions

OBJECTIVE

We aimed to analyze deoxycytidine-deoxyguanosine dinucleotide (CpGs) methylation profiles in DIO2, GPX3, and TXNRD1 promoter regions in osteoarthritis (OA) and Kashin-Beck disease (KBD) patients.

METHODS

Blood samples were collected from 16 primary OA patients and corresponding 16 healthy individuals and analyzed for methylations in the CpGs of DIO2, GPX3, and TXNRD1 promoter regions using MALDI-TOF-MS. The methylation profiles of these regions were then compared between OA and KBD patients.

RESULTS

DIO2-1_CpG_2 and DIO2-1_CpG_3 methylations were significantly lower in OA than KBD patients (P < 0.05). A similar trend was observed for GPX3-1_CpG_4, GPX3-1_CpG_7, GPX3-1_CpG_8.9.10, GPX3-1_CpG_13.14.15 and GPX3-1_CpG_16 (P < 0.05) as well as TXNRD1-1_CpG_1 and TXNRD1-1_CpG_2 methylation between OA and KBD patients (P < 0.05). However, there was no difference in methylation levels of other CpGs between the 2 groups (P > 0.05).

CONCLUSION

OA and KBD patients display distinct methylation profiles in the CpG sites of DIO2, GPX3, and TXNRD1 promoter regions. These findings provide a strong background and new perspective for future studies on mechanisms underlying epigenetic regulation of selenoprotein genes associated with OA and KBD diseases.

Virtual pathway explorer (viPEr) and pathway enrichment analysis tool (PEANuT): creating and analyzing focus networks to identify cross-talk between molecules and pathways

Background

Interpreting large-scale studies from microarrays or next-generation sequencing for further experimental testing remains one of the major challenges in quantitative biology. Combining expression with physical or genetic interaction data has already been successfully applied to enhance knowledge from all types of high-throughput studies. Yet, toolboxes for navigating and understanding even small gene or protein networks are poorly developed.

Results

We introduce two Cytoscape plug-ins, which support the generation and interpretation of experiment-based interaction networks. The virtual pathway explorer viPEr creates so-called focus networks by joining a list of experimentally determined genes with the interactome of a specific organism. viPEr calculates all paths between two or more user-selected nodes, or explores the neighborhood of a single selected node. Numerical values from expression studies assigned to the nodes serve to score identified paths. The pathway enrichment analysis tool PEANuT annotates networks with pathway information from various sources and calculates enriched pathways between a focus and a background network. Using time series expression data of atorvastatin treated primary hepatocytes from six patients, we demonstrate the handling and applicability of viPEr and PEANuT. Based on our investigations using viPEr and PEANuT, we suggest a role of the FoxA1/A2/A3 transcriptional network in the cellular response to atorvastatin treatment. Moreover, we find an enrichment of metabolic and cancer pathways in the Fox transcriptional network and demonstrate a patient-specific reaction to the drug.

Conclusions

The Cytoscape plug-in viPEr integrates –omics data with interactome data. It supports the interpretation and navigation of large-scale datasets by creating focus networks, facilitating mechanistic predictions from –omics studies. PEANuT provides an up-front method to identify underlying biological principles by calculating enriched pathways in focus networks.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-2017-z) contains supplementary material, which is available to authorized users.

TrxR1 as a potent regulator of the Nrf2-Keap1 response system

SIGNIFICANCE

All cells must maintain a balance between oxidants and reductants, while allowing for fluctuations in redox states triggered by signaling, altered metabolic flow, or extracellular stimuli. Furthermore, they must be able to rapidly sense and react to various challenges that would disrupt the redox homeostasis.

RECENT ADVANCES

Many studies have identified Keap1 as a key sensor for oxidative or electrophilic stress, with modification of Keap1 by oxidation or electrophiles triggering Nrf2-mediated transcriptional induction of enzymes supporting reductive and detoxification pathways. However, additional mechanisms for Nrf2 regulation are likely to exist upstream of, or in parallel with, Keap1.

CRITICAL ISSUES

Here, we propose that the mammalian selenoprotein thioredoxin reductase 1 (TrxR1) is a potent regulator of Nrf2. A high chemical reactivity of TrxR1 and its vital role for the thioredoxin (Trx) system distinguishes TrxR1 as a prime target for electrophilic challenges. Chemical modification of the selenocysteine (Sec) in TrxR1 by electrophiles leads to rapid inhibition of thioredoxin disulfide reductase activity, often combined with induction of NADPH oxidase activity of the derivatized enzyme, thereby affecting many downstream redox pathways. The notion of TrxR1 as a regulator of Nrf2 is supported by many publications on effects in human cells of selenium deficiency, oxidative stress or electrophile exposure, as well as the phenotypes of genetic mouse models.

FUTURE DIRECTIONS

Investigation of the role of TrxR1 as a regulator of Nrf2 activation will facilitate further studies of redox control in diverse cells and tissues of mammals, and possibly also in animals of other classes.

Simvastatin induces growth inhibition and apoptosis in HepG2 and Huh7 hepatocellular carcinoma cells via upregulation of Notch1 expression

Statins, cholesterol‑lowering drugs, are one of the most commonly prescribed types of medications. Previous studies have suggested that simvastatin may inhibit the cell function and tumor growth of hepatocellular carcinoma (HCC) cells; however, the molecular mechanisms underlying simvastatin‑induced apoptosis in HCC cells remains to be elucidated. The aim of the present study was to investigate the role of simvastatin in the regulation of cell viability, proliferation and apoptosis in HepG2 and Huh7 HCC cells, and to elucidate the specific regulatory mechanisms by which simvastatin proceeds. MTT, trypan blue and flow cytometric analyses were performed in order to detect viability, proliferation and apoptosis in HepG2 and Huh7 cells. The results of the present study demonstrated that simvastatin significantly decreased cell viability and proliferation as well as increased apoptosis in HepG2 and Huh7 cells compared to that in untreated cells. In addition, reverse transcription quantitative polymerase chain reaction and western blot analysis revealed that simvastatin‑treated cells exhibited increased expression levles of Notch1, p53, and Bax, as well as decreased expression levels of B cell lymphoma 2; furthermore, Notch1 upregulation resulted in the inhibition of Akt phosphorylation. In conclusion, the results of the present study indicated that simvastatin significantly promoted apoptosis in HCC cells, the mechanism of which may have proceeded via the upregualtion of the Notch1 gene in the Akt‑dependent signaling pathway.

Statin treatment reduces the risk of hepatocellular carcinoma but not colon cancer-results from a nationwide case-control study in Sweden

BACKGROUND

Several studies have indicated that statins may have anticarcinogenic effects. The aim of the present study was to investigate if statin treatment was associated with a reduced risk of hepatocellular carcinoma (HCC) or colon cancer.

METHODS

A nationwide case-control study was carried out in which all cases of HCC and colon cancer in the Swedish population above 40 years of age between 1 July 2006 and 31 December 2010 were identified in the Swedish Cancer Register. For every case, five controls were selected and matched on age and sex. Data on statin use was extracted from the Swedish Prescribed Drug Register. We estimated risks using conditional logistic regression and adjusted for educational level, concomitant medications and comorbidity.

RESULTS

Identified were 3994 cases of HCC and matched with 19.970 controls, and 21.143 cases of colon cancer were identified and matched with 105.715 controls. In the adjusted analysis, the odds ratio (OR) for HCC among statin users was 0.88 (95% confidence interval (CI) 0.81-0.96), and the OR for colon cancer was 1.04 (95%CI 1.00-1.08) compared with non-users.

CONCLUSION

Statin use was associated with a modest decreased risk of HCC but did not influence the risk of colon cancer. Future randomized placebo-controlled trials in HCC high-risk patients are warranted to further investigate the possible prophylactic effect of statins in HCC.