Vitamin E reduces chromosomal damage and inhibits hepatic tumor formation in a transgenic mouse model

Genome-wide association study and high-quality gene mining related to soybean protein and fat

BACKGROUND

Soybean is one of the most important oil crops in the world, and its protein and fat are the primary sources of edible oil and vegetable protein. The effective components in soybean protein and fat have positive effects on improving human immunity, anti-tumor, and regulating blood lipids and metabolism. Therefore, increasing the contents of protein and fat in soybeans is essential for improving the quality of soybeans.

RESULTS

This study selected 292 soybean lines from different regions as experimental materials, based on SLAF-seq sequencing technology, and performed genome-wide association study (GWAS) on the phenotype data from 2019-2021 Planted at the experimental base of Jilin Agricultural University, such as the contents of protein and fat of soybeans. Through the GLM model and MLM model, four SNP sites (Gm09_39012959, Gm12_35492373, Gm16_9297124, and Gm20_24678362) that were significantly related to soybean fat content were associated for three consecutive years, and two SNP sites (Gm09_39012959 and Gm20_24678362) that were significantly related to soybean protein content were associated. By the annotation and enrichment of genes within the 100 Kb region of SNP loci flanking, two genes (Glyma.09G158100 and Glyma.09G158200) related to soybean protein synthesis and one gene (Glyma.12G180200) related to lipid metabolism were selected. By the preliminary verification of expression levels of genes with qPCR, it is found that during the periods of R6 and R7 of the accumulation of soybean protein and fat, Glyma.09G158100 and Glyma.09G158200 are positive regulatory genes that promote protein synthesis and accumulation, while Glyma.12G180200 is the negative regulatory gene that inhibits fat accumulation.

CONCLUSIONS

These results lay the basis for further verifying the gene function and studying the molecular mechanisms regulating the accumulation of protein and fat in soybean seeds.

Role of vitamin E in the treatment of non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH), a severe form of non-alcoholic fatty liver disease (NAFLD), can progress to cirrhosis, hepatocellular carcinoma (HCC), and hepatic failure/liver transplantation. Indeed, NASH will soon be the leading cause of HCC and liver transplantation. Lifestyle intervention represents the cornerstone of NASH treatment, but it is difficult to sustain. However, no pharmacotherapies for NASH have been approved. Oxidative stress has been implicated as one of the key factors in the pathogenesis of NASH. Systematic reviews with meta-analyses have confirmed that vitamin E reduces transaminase activities and may resolve NASH histopathology without improving hepatic fibrosis. However, vitamin E is not recommended for the treatment of NASH in diabetes, NAFLD without liver biopsy, NASH cirrhosis, or cryptogenic cirrhosis. Nevertheless, vitamin E supplementation may improve clinical outcomes in patients with NASH and bridging fibrosis or cirrhosis. Further studies are warranted to confirm such effects of vitamin E and that it would reduce overall mortality/morbidity without increasing the incidence of cardiovascular events. Future clinical trials of the use of vitamin E in combination with other anti-fibrotic agents may demonstrate an additive or synergistic therapeutic effect. Vitamin E is the first-line pharmacotherapy for NASH, according to the consensus of global academic societies.

The genotoxic effects of perchloroethylene in human peripheral blood lymphocytes and the possible ameliorative role of α-tocopherol

Perchloroethylene (PCE), also known as tetrachloroethylene, is a commercially important chlorinated solvent commonly used in dry cleaning, textile processing, and metal degreasing industries. According to the available studies, the potential genotoxic impacts of this chlorinated solvent on human beings are still controversial. The present work was carried out to determine the genotoxic effects of PCE on human peripheral blood lymphocytes (PBLs) using chromosome aberrations (CAs) and cytokinesis-block micronucleus (CBMN) tests. Additionally, the antigenotoxic potential of α-tocopherol (α-Toc), a well-known antioxidant agent, on human lymphocytes treated with PCE in vitro was assessed. The cells were exposed for 48 h to PCE (25, 50, 100, and 150 μg/mL) alone as well as in combination with α-Toc (100 μg/mL). The findings of the study suggested that, relative to solvent control, PCE significantly increased the structural CA and MN formation for all concentrations. However, simultaneous treatment of PCE and α-Toc caused a significant reduction of CAs and MNi as compared to cultures treated with PCE alone. Besides, the results showed that PCE has cytotoxic effects on human PBLs as indicated by the significant decrease in mitotic index (MI) and nuclear division index (NDI). Nevertheless, the co-treatment of α-Toc with PCE did not reduce the cytotoxicity of PCE at a significant level. In conclusion, it can be suggested that PCE is genotoxic and cytotoxic in human PBLs, and α-Toc has an antigenotoxic effect on PCE-induced genotoxicity but has no significant effect on the cytotoxicity triggered by PCE.

Ameliorative effect of enhanced Fischer ratio flaxseed protein hydrolysate in combination with antioxidant micronutrients on ethanol-induced hepatic damage in a rat model

Alcohol abuse causes severe metabolic abnormalities inducing hepatic damage and malnutrition. Since higher Fischer ratio proteins have therapeutic value in liver diseases, an investigation was undertaken to study the ameliorative effect of the enhanced Fischer ratio flaxseed protein hydrolysate (EFR-FPH) alone and in combination with antioxidant micronutrients on ethanol-induced hepatotoxicity in a rat model. The EFR-FPH was prepared by dual enzymatic hydrolysis and charcoal treatment of flaxseed protein. The ratio of the branched-chain:aromatic amino acids (Fischer ratio) was found to be 7·08. The EFR-FPH, characterised using LC-MS/MS, showed the abundance of free leucine and isoleucine compared with phenylalanine and tyrosine. The matrix-assisted laser desorption/ionisation-time of flight MS analysis revealed the larger peptides present in EFR-FPH with mass 2·3 kDa. The EFR-FPH improved the nutritional status, liver function and antioxidant defense in the ethanol hepatotoxicity-induced rat model. The hepatoprotective effect of EFR-FPH was significantly enhanced when combined with selenium or vitamin E. Ethanol-induced changes in the liver tissue were effectively suppressed in the groups receiving EFR-FPH. Flaxseed-based hepatoprotective dietary supplement was formulated incorporating an optimum level of EFR-FPH (10 %) based on sensory acceptability and was fortified with selenium and vitamin E. The hepatoprotective formulation significantly lowered aspartate transaminase, alanine transaminase, alkaline phosphatase and bilirubin by 47, 61, 55 and 78 %, respectively, and improved the antioxidant defense in the ethanol hepatotoxicity-induced rat model. The current investigation suggests that EFR-FPH in synergy with antioxidant micronutrients is potent in ameliorating ethanol-induced hepatotoxicity and has a potential to form a hepatoprotective dietary supplement.

Tumor cell-activated "Sustainable ROS Generator" with homogeneous intratumoral distribution property for improved anti-tumor therapy

Photodynamic therapy (PDT) holds a number of advantages for tumor therapy. However, its therapeutic efficiency is limited by non-sustainable reactive oxygen species (ROS) generation and heterogeneous distribution of photosensitizer (PS) in tumor. Herein, a "Sustainable ROS Generator" (SRG) is developed for efficient antitumor therapy. Methods: SRG was prepared by encapsulating small-sized Mn₃O₄-Ce6 nanoparticles (MC) into dendritic mesoporous silica nanoparticles (DMSNs) and then enveloped with hyaluronic acid (HA). Due to the high concentration of HAase in tumor tissue, the small-sized MC could be released from DMSNs and homogeneously distributed in whole tumor. Then, the released MC would be uptaken by tumor cells and degraded by high levels of intracellular glutathione (GSH), disrupting intracellular redox homeostasis. More importantly, the released Ce6 could efficiently generate singlet oxygen (¹O₂) under laser irradiation until the tissue oxygen was exhausted, and the manganese ion (Mn²⁺) generated by degraded MC would then convert the low toxic by-product (H₂O₂) of PDT to the most harmful ROS (·OH) for sustainable and recyclable ROS generation. Results: MC could be homogeneously distributed in whole tumor and significantly reduced the level of intracellular GSH. At 2 h after PDT, obvious intracellular ROS production was still observed. Moreover, during oxygen recovery in tumor tissue, ·OH could be continuously produced, and the nanosystem could induce 82% of cell death comparing with 30% of cell death induced by free Ce6. For in vivo PDT, SRG achieved a complete inhibition on tumor growth. Conclusion: Based on these findings, we conclude that the designed SRG could induce sustainable ROS generation, homogeneous intratumoral distribution and intracellular redox homeostasis disruption, presenting an efficient strategy for enhanced ROS-mediated anti-tumor therapy.

Pathogenesis of Human Immunodeficiency Virus-Mycobacterium tuberculosis Co-Infection

Given that infection with Mycobacterium tuberculosis (Mtb) is the leading cause of death amongst individuals living with HIV, understanding the complex mechanisms by which Mtb exacerbates HIV infection may lead to improved treatment options or adjuvant therapies. While it is well-understood how HIV compromises the immune system and leaves the host vulnerable to opportunistic infections such as Mtb, less is known about the interplay of disease once active Mtb is established. This review explores how glutathione (GSH) depletion, T cell exhaustion, granuloma formation, and TNF-α upregulation, as a result of Mtb infection, leads to an increase in HIV disease severity. This review also examines the difficulties of treating coinfected patients and suggests further research on the clinical use of GSH supplementation.

HIV-1 Reverse Transcriptase Promotes Tumor Growth and Metastasis Formation via ROS-Dependent Upregulation of Twist

HIV-induced immune suppression results in the high prevalence of HIV/AIDS-associated malignancies including Kaposi sarcoma, non-Hodgkin lymphoma, and cervical cancer. HIV-infected people are also at an increased risk of “non-AIDS-defining” malignancies not directly linked to immune suppression but associated with viral infections. Their incidence is increasing despite successful antiretroviral therapy. The mechanism behind this phenomenon remains unclear. Here, we obtained daughter clones of murine mammary gland adenocarcinoma 4T1luc2 cells expressing consensus reverse transcriptase of HIV-1 subtype A FSU_A strain (RT_A) with and without primary mutations of drug resistance. In in vitro tests, mutations of resistance to nucleoside inhibitors K65R/M184V reduced the polymerase, and to nonnucleoside inhibitors K103N/G190S, the RNase H activities of RT_A. Expression of these RT_A variants in 4T1luc2 cells led to increased production of the reactive oxygen species (ROS), lipid peroxidation, enhanced cell motility in the wound healing assay, and upregulation of expression of Vimentin and Twist. These properties, particularly, the expression of Twist, correlated with the levels of expression RT_A and/or the production of ROS. When implanted into syngeneic BALB/C mice, 4T1luc2 cells expressing nonmutated RT_A demonstrated enhanced rate of tumor growth and increased metastatic activity, dependent on the level of expression of RT_A and Twist. No enhancement was observed for the clones expressing mutated RT_A variants. Plausible mechanisms are discussed involving differential interactions of mutated and nonmutated RTs with its cellular partners involved in the regulation of ROS. This study establishes links between the expression of HIV-1 RT, production of ROS, induction of EMT, and enhanced propagation of RT-expressing tumor cells. Such scenario can be proposed as one of the mechanisms of HIV-induced/enhanced carcinogenesis not associated with immune suppression.

Vitamin E protects against cisplatin-induced genotoxicity in human lymphocytes

Cisplatin is an anticancer drug that is widely used in treatments of human malignancies such as ovaries,' testes,' and solid tumors of the head and neck. However, the use of cisplatin in the treatments can be associated with DNA damage and high risk to the development of secondary malignancies. Vitamin E is a strong lipophilic antioxidant that has the ability to protect normal cells from chromosomal damage and promote the repair of the damaged DNA. In the current study, the possible protective effect of vitamin E on DNA damage induced by cisplatin was investigated. For that, chromosomal aberrations (CAs) frequency and the number of sister chromatid exchanges (SCEs) were measured in cultured human lymphocytes. Results showed that cisplatin statistically significant increases in the number of cells with CAs (P < 0.05) and in the frequency of SCEs (P < 0.05) as compared to the control group. These increases were significantly lowered by pretreatment of cells with vitamin E. Additionally, cisplatin reduced mitotic index at used concentrations (P < 0.05), which was normalized by vitamin E. Therefore, we conclude that vitamin E can prevent the genotoxicity of cisplatin on cultured human lymphocyte.

Extraction of Tocopherol from Soybean Oil Deodorizer Distillate by Deep Eutectic Solvents

Natural tocopherols have strong antioxidant and physiological functions, which are mainly produced from vegetable oil deodorized distillates. In this work, a simple and green solvent extraction method based on deep eutectic solvent has been developed to simultaneously extract three isomers of tocopherols (α, γ and δ-tocopherols) from soybean oil deodorizer distillate (SODD). The key factor to affect the solvent extraction efficiency was proposed that phenolic deep eutectic solvents interacted with targeted tocopherols mainly through π-π bonds interaction. This sustainable extraction process included two steps. Firstly, total tocopherols were extracted from SODD at room temperature by phenolic deep eutectic solvent composed of ChCl and p-cresol. Subsequently, tocopherols were successfully separated from deep eutectic solvent phase by re-extraction with n-hexane, and tocopherols products could be simply recovered. Under the optimum extraction conditions, the extraction efficiency of total tocopherols (α, γ and δ-tocopherols) from SODD was 77.6% after extraction with phenolic deep eutectic solvent.

Contradictory effects of mitochondria- and non-mitochondria-targeted antioxidants on hepatocarcinogenesis by altering DNA repair in mice

Conflicting effects of antioxidant supplementation on cancer prevention or promotion is of great concern to healthy people and cancer patients. Despite recent studies about antioxidants accelerating the progression of lung cancer and melanoma, antioxidants may still play a role in cancer prevention. Both tumor and antioxidants types influence the actual efficacy. However, little is known about the impact of different types of antioxidants on primary hepatocellular carcinoma (HCC), including non-mitochondrial- and mitochondrial-targeted antioxidants. Utilizing mouse models of chemical hepatocarcinogenesis, we showed that administration of non-mitochondria-targeted antioxidants N-acetylcysteine (NAC) and the soluble vitamin E analog, Trolox, prevented tumorigenesis, whereas administration of mitochondria-targeted antioxidants SS-31 (the mitochondria-targeted peptide) and Mito-Q (a derivative of ubiquinone) facilitated tumorigenesis. RNA sequencing revealed that NAC and SS-31 caused very different changes in the oxidation-reduction state and DNA damage response. In diethylnitrosamine (DEN)-treated primary hepatocytes, NAC and Trolox alleviated DNA damage by activating ataxia-telangiectasia mutated (ATM)/ATM and Rad3-related (ATR) for DNA repair whereas SS-31 and Mito-Q aggravated damage by inactivating them. Interestingly, partial recovery of SS-31-scavengened mitochondrial reactive oxygen species (mtROS) could alleviate SS-31-aggravated DNA damage. Localization of ATM between mitochondria and nuclei was altered after NAC and SS-31 treatment. Furthermore, blockage of phospho-ATR (p-ATR) led to the recurrence of NAC-ameliorated DEN HCC. In contrast, reactivation of p-ATR blocked SS-31-promoted DEN HCC. Conclusion: These results demonstrate that the type of antioxidants plays a previously unappreciated role in hepatocarcinogenesis, and provide a mechanistic rationale for exploring the therapeutic use of antioxidants for liver cancer. (Hepatology 2018;67:623-635).

Vitamin E Modifies High-Fat Diet-Induced Increase of DNA Strand Breaks, and Changes in Expression and DNA Methylation of Dnmt1 and MLH1 in C57BL/6J Male Mice

Obesity is associated with low-grade inflammation, increased ROS production and DNA damage. Supplementation with antioxidants might ameliorate DNA damage and support epigenetic regulation of DNA repair. C57BL/6J male mice were fed a high-fat (HFD) or a control diet (CD) with and without vitamin E supplementation (4.5 mg/kg body weight (b.w.)) for four months. DNA damage, DNA promoter methylation and gene expression of Dnmt1 and a DNA repair gene (MLH1) were assayed in liver and colon. The HFD resulted in organ specific changes in DNA damage, the epigenetically important Dnmt1 gene, and the DNA repair gene MLH1. Vitamin E reduced DNA damage and showed organ-specific effects on MLH1 and Dnmt1 gene expression and methylation. These results suggest that interventions with antioxidants and epigenetic active food ingredients should be developed as an effective prevention for obesity—and oxidative stress—induced health risks.

Effect of vitrification on the mRNA transcriptome of bovine oocytes

Vitrification has been shown to decrease the developmental capacity of mammalian oocytes, and this is closely associated with the abnormal mRNA expressions of vitrified oocytes. However, the effect of vitrification on transcriptional machinery of oocytes examined by RNA sequencing (RNA-seq) has yet to be defined. In the present study, the mRNA transcriptomes of fresh and vitrified bovine oocytes were analysed by Smart-seq2 with the differently expressed genes determined by DEseq2 (an adjusted p-value of .05 and a minimum fold change of 2). The differentially expressed mRNAs were then searched against the Gene Ontology (GO) and Genomes (KEGG) database. Finally, the mRNA expressions of 10 candidate genes were validated using quantitative real-time PCR (qRT-PCR). Approximately 12,000 genes were detected in each sample of fresh or vitrified oocytes. Of these, the expression levels of 102 genes differed significantly in vitrified groups: 12 genes mainly involved in cell cycle, fertilization and glucose metabolism were upregulated, and 90 genes mainly involved in mitochondria, ribosomal protein, cytoskeleton, transmembrane protein, cell cycle and calcium ions were downregulated. GO analysis showed that these genes were mainly enriched in terms of membrane-bounded organelles, macromolecular complex, and intracellular part. The mRNA expression levels of 10 candidate genes selected randomly were in agreement with the results of the RNA-seq. In conclusion, our results showed that vitrification affected the mRNA transcriptome of bovine oocytes by downregulating genes, which contributed to the decreased developmental capacity of vitrified oocytes. Our findings will be useful in determining approaches to improve the efficiency of vitrified oocytes.

Antioxidant strategies in respiratory medicine

Pulmonary oxidant stress plays an important pathogenetic role in disease conditions including acute lung injury/adult respiratory distress syndrome (ALI/ARDS), hyperoxia, ischemia-reperfusion, sepsis, radiation injury, lung transplantation, COPD, and inflammation. Reactive oxygen species (ROS), released from activated macrophages and leukocytes or formed in the pulmonary epithelial and endothelial cells, damage the lungs and initiate cascades of pro-inflammatory reactions propagating pulmonary and systemic stress. Diverse molecules including small organic compounds (e.g. gluthatione, tocopherol (vitamin E), flavonoids) serve as natural antioxidants that reduce oxidized cellular components, decompose ROS and detoxify toxic oxidation products. Antioxidant enzymes can either facilitate these antioxidant reactions (e.g. peroxidases using glutathione as a reducing agent) or directly decompose ROS (e.g. superoxide dismutases [SOD] and catalase). Many antioxidant agents are being tested for treatment of pulmonary oxidant stress. The administration of small antioxidants via the oral, intratracheal and vascular routes for the treatment of short- and long-term oxidant stress showed rather modest protective effects in animal and human studies. Intratracheal and intravascular administration of antioxidant enzymes are being currently tested for the treatment of acute oxidant stress. For example, intratracheal administration of recombinant human SOD is protective in premature infants exposed to hyperoxia. However, animal and human studies show that more effective delivery of drugs to cells experiencing oxidant stress is needed to improve protection. Diverse delivery systems for antioxidants including liposomes, chemical modifications (e.g. attachment of masking pegylated [PEG]-groups) and coupling to affinity carriers (e.g. antibodies against cellular adhesion molecules) are being employed and currently tested, mostly in animal and, to a limited extent, in humans, for the treatment of oxidant stress. Further studies are needed, however, in order to develop and establish effective applications of pulmonary antioxidant interventions useful in clinical practice. Although beyond the scope of this review, antioxidant gene therapies may eventually provide a strategy for the management of subacute and chronic pulmonary oxidant stress.

The rs6060566 of the reactive oxygen species modulator 1 (Romo-1) gene affects Romo-1 expression and the development of diabetic retinopathy in Caucasians with type 2 diabetes

PURPOSE

The aim of this study was to examine the role of the rs6060566 polymorphism of the reactive oxygen species modulator 1 (Romo-1) gene in the development of diabetic retinopathy (DR) in Caucasians with type 2 diabetes (T2DM). Moreover, another aim was to investigate the effect of Romo-1 genotypes on Romo-1 expression in fibrovascular membranes from patients with proliferative DR.

METHODS

A total of 806 subjects with T2DM were enrolled in cross-sectional case-control study: 278 patients with DR and 528 subjects without clinical signs of DR. Genetical analysis was performed in 806 subjects with T2DM. Moreover, immunohistochemical analysis of 40 fibrovascular membranes of patients with proliferative DR was performed. The number of positive (labelled) cells per area - numerical areal density of the Romo-1-positive cells (the number of positive cells/mm(2) ) - was calculated.

RESULTS

A significantly higher frequency of the CC genotype of the rs6060566 polymorphism of the Romo-1 gene was found in subjects with T2DM with DR compared to those without DR (odds ratio=3.3, 95% confidence interval=1.1-8.8; p = 0.024). Moreover, the Romo-1 C allele was found to effect Romo-1 expression in fibrovascular membranes of patients with proliferative DR.

CONCLUSIONS

The rs6060566 polymorphism of the Romo-1 gene was found to be an independent risk factor for DR in Caucasians with T2DM. Moreover, the rs6060566 is most probably functional and its effect might be mediated through the increased expression of Romo-1 in the retina.

Prevention of hepatocellular carcinoma: Focusing on antioxidant therapy

Oxidative stress has been investigated in the context of alcoholic liver injury for many years and shown to be a causal factor of chronic hepatitis C (CHC), nonalcoholic steatohepatitis (NASH), drug-induced liver injury, Wilson’s disease, and hemochromatosis. In CHC, it has been demonstrated that oxidative stress plays an important role in hepatocarcinogenesis. In cases with persistent hepatitis due to failure of hepatitis C virus eradication, or chronic liver disease, such as NASH, the treatment of which remains unestablished, it is important to reduce serum alanine aminotransferase levels and prevent liver fibrosis and development of hepatocellular carcinoma. This also suggests the importance of antioxidant therapy. Among treatment options where it would be expected that anti-inflammatory activity plays a role in their confirmed efficacy for chronic hepatitis, iron depletion therapy, glycyrrhizin, ursodeoxycholic acid, Sho-Saiko-To, and vitamin E can all be considered antioxidant therapies. To date, however, the ability of these treatments to prevent cancer has been confirmed only in CHC. Nevertheless, anti-inflammatory and anti-fibrotic effects have been demonstrated in other liver diseases and these therapies may potentially be effective for cancer prevention.

Treatment response in the PIVENS trial is associated with decreased Hedgehog pathway activity

Hedgehog (Hh) ligand production by ballooned hepatocytes drives nonalcoholic steatohepatitis (NASH) progression in mice. The NIDDK-sponsored PIVENS trial (NCT00063622) showed that vitamin E (VitE) improved NASH. We investigated whether VitE treatment and improvement in NASH were associated with changes in Hh pathway activity. Immunohistochemistry (IHC) was performed on both pre- and posttreatment liver biopsies of 59 PIVENS patients randomized to VitE (n = 30) or placebo (n = 29). Sonic Hh (Shh) ligand-producing cells and Shh-responsive cells were quantified. The latter was accomplished by triple IHC for gli2+ (marker of Hh signaling), sox-9 (progenitor marker), and α-smooth muscle actin (α-SMA; myofibroblast marker). Ballooned hepatocytes were quantified by keratin 8/18 and ubiquitin (K8/18/Ub) staining. IHC results were correlated with primary clinical and histologic PIVENS data. Pretreatment clinical, histologic, and IHC parameters did not differ significantly in the two treatment groups. Regardless of treatment arm, the number of Shh+ hepatocytes correlated with K8/18/Ub foci (r(2) = 0.47, P < 0.001) and aspartate aminotransferase (AST) (r(2) = 0.15, P = 0.002). Treatment-related changes in the numbers of Shh+ hepatocytes correlated with changes in serum AST (partial r(2) = 0.75, P < 0.0001), hepatocyte ballooning (P = 0.004), the ductular reaction (i.e., numbers of gli2+/sox9+ cells; P = 0.03 and α-SMA+ cells; P = 0.10), and fibrosis stage (P = 0.02). Treatment response was associated with a greater decrease in Shh+ hepatocytes than nonresponse (P = 0.007). The VitE group demonstrated a greater reduction in K8/18/Ub+ foci (P < 0.08) and Shh+ hepatocytes (P < 0.05) than the placebo group, effects that became more significant after correction for baseline differences and multiple linear regression analysis.

CONCLUSION

During PIVENS, treatment response correlated with loss of Shh+ hepatocytes and improvement in Hh-regulated processes that promote NASH progression.

Association of serum α-tocopherol, β-carotene, and retinol with liver cancer incidence and chronic liver disease mortality

BACKGROUND

Micronutrients may influence the development or progression of liver cancer and liver disease. We evaluated the association of serum α-tocopherol, β-carotene, and retinol with incident liver cancer and chronic liver disease (CLD) mortality in a prospective cohort of middle-aged Finnish male smokers.

METHODS

Baseline and 3-year follow-up serum were available from 29,046 and 22,805 men, respectively. After 24 years of follow-up, 208 men were diagnosed with liver cancer and 237 died from CLD. Hazards ratios and 95% confidence intervals were calculated for highest vs lowest quartiles from multivariate proportional hazards models.

RESULTS

Higher β-carotene and retinol levels were associated with less liver cancer (β-carotene: 0.35, 0.22-0.55, P-trend <0.0001; retinol: 0.58, 0.39-0.85, P-trend=0.0009) and CLD mortality (β-carotene: 0.47, 0.30-0.75, P-trend=0.001; retinol: 0.55, 0.38-0.78, P-trend=0.0007). α-Tocopherol was associated with CLD mortality (0.63, 0.40-0.99, P-trend=0.06), but not with liver cancer (1.06, 0.64-1.74, P-trend=0.77). Participants with higher levels of β-carotene and retinol, but not α-tocopherol, at both baseline and year 3 had lower risk of each outcome than those with lower levels.

CONCLUSIONS

Our findings suggest that higher concentrations of β-carotene and retinol are associated with incident liver cancer and CLD. However, such data do not indicate that supplementation should be considered for these diseases.

Romo1 is associated with ROS production and cellular growth in human gliomas

Romo1 is a mitochondrial protein whose elevated expression is commonly observed in various types of human cancers. However, the expression status of Romo1 and its implication in the pathogenesis of human glioblastoma (GBM) remain largely undefined. To understand the role of Romo1 in the progression of GBM, we explored its expression in a series of GBM tissues and cell lines and determined its effect on ROS production, cell proliferation, and tumor growth. Romo1 was frequently overexpressed at the mRNA level in both primary tumors and cell lines and its elevation was more commonly observed in high grade tumors versus low grade tumors. Romo1 expression was associated with ROS production and its knockdown led to a marked reduction of in vitro cellular growth and anchorage-independent growth of GBM. Consistently, Romo1 depletion induced a G2/M arrest of the cell cycle that was accompanied with accumulation of phospho-cdc2. Furthermore, a mouse xenograft assay revealed that Romo1 depletion significantly decreased tumor formation and growth. Therefore, our data demonstrate that Romo1 upregulation is a common event in human GBMs and contributes to the malignant tumor progression, suggesting that Romo1 could be a new therapeutic target for human GBM.

In vivo detection of a novel endogenous etheno-DNA adduct derived from arachidonic acid and the effects of antioxidants on its formation

Previous studies showed that 7-(1',2'-dihydroxyheptyl)-substituted etheno DNA adducts are products of reactions with the epoxide of (E)-4-hydroxy-2-nonenal, an oxidation product of ω-6 polyunsaturated fatty acids (PUFAs). In this work, we report the detection of 7-(1',2'-dihydroxyheptyl)-1,N(6)-ethenodeoxyadenosine (DHHedA) in rodent and human tissues by two independent methods: a (32)P-postlabeling/HPLC method and an isotope dilution liquid chromatography-electrospray ionization-tandem mass spectrometry method, demonstrating for the first time that DHHedA is a background DNA lesion in vivo. We showed that DHHedA can be formed upon incubation of arachidonic acid with deoxyadenosine, supporting the notion that ω-6 PUFAs are the endogenous source of DHHedA formation. Because cyclic adducts are derived from the oxidation of PUFAs, we subsequently examined the effects of antioxidants, α-lipoic acid, Polyphenon E, and vitamin E, on the formation of DHHedA and γ-hydroxy-1,N(2)-propanodeoxyguanosine (γ-OHPdG), a widely studied acrolein-derived adduct arising from oxidized PUFAs, in the livers of Long Evans Cinnamon (LEC) rats. LEC rats are afflicted with elevated lipid peroxidation and prone to the development of hepatocellular carcinomas. The results showed that although the survival of LEC rats was increased significantly by α-lipoic acid, none of the antioxidants inhibited the formation of DHHedA, and only Polyphenon E decreased the formation of γ-OHPdG. In contrast, vitamin E caused a significant increase in the formation of both γ-OHPdG and DHHedA in the livers of LEC rats.

Oxidative stress and hepatic Nox proteins in chronic hepatitis C and hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common liver cancer and a leading cause of cancer-related mortality in the world. Hepatitis C virus (HCV) is a major etiologic agent of HCC. A majority of HCV infections lead to chronic infection that can progress to cirrhosis and, eventually, HCC and liver failure. A common pathogenic feature present in HCV infection, and other conditions leading to HCC, is oxidative stress. HCV directly increases superoxide and H2O2 formation in hepatocytes by elevating Nox protein expression and sensitizing mitochondria to reactive oxygen species generation while decreasing glutathione. Nitric oxide synthesis and hepatic iron are also elevated. Furthermore, activation of phagocytic NADPH oxidase (Nox) 2 of host immune cells is likely to exacerbate oxidative stress in HCV-infected patients. Key mechanisms of HCC include genome instability, epigenetic regulation, inflammation with chronic tissue injury and sustained cell proliferation, and modulation of cell growth and death. Oxidative stress, or Nox proteins, plays various roles in these mechanisms. Nox proteins also function in hepatic fibrosis, which commonly precedes HCC, and Nox4 elevation by HCV is mediated by transforming growth factor β. This review summarizes mechanisms of oncogenesis by HCV, highlighting the roles of oxidative stress and hepatic Nox enzymes in HCC.

Lycopene modulates initiation of N-nitrosodiethylamine induced hepatocarcinogenesis: studies on chromosomal abnormalities, membrane fluidity and antioxidant defense system

Oxidative damage due to free radicals generated during nitrosamine metabolism has been suggested as one of the major cause for the initiation of hepatocarcinogenesis. Lycopene, is a well known antioxidant and have promising preventive potentials, however the mechanism of action remain hypothetical and unclear. To investigate the involvement of lycopene extracted from tomatoes (LycT) against oxidative stress induced deleterious effect of N-nitrosodiethylamine (NDEA) on cellular macromolecules, female Balb/c mice were divided in four groups: Control, NDEA (cumulative dose of 200mg NDEA/kg body weight injected intraperitoneally in 8 weeks), LycT (5mg/kg body weight given orally on alternate days, throughout the study) and LycT+NDEA (co-administration of LycT and NDEA). NDEA treatment commenced after 2 weeks of LycT administration. At the end of NDEA exposure i.e., at 10th week, enhanced activities of hepatic phase I enzymes, levels of reactive oxygen species (ROS), lipid peroxidation (LPO) was observed in NDEA group which may have contributed in chromosomal aberrations, enhanced micronucleated cell score, membrane fluidity and serum liver marker enzymes. A significant decrease in enzymatic and non-enzymatic antioxidant system could delineate the mechanism behind such NDEA insults. LycT pre-treatment to NDEA challenged group showed lower chromosomal abnormalities, micronucleated cells score, ROS, LPO levels and liver enzymes. Lycopene aids in normalizing the membrane fluidity and enhancing the activity of antioxidant enzymes and reduced glutathione which could account for the reduced oxidative damage in LycT+NDEA group. It seemed that lycopene supplementation target multiple dys-regulated pathways during initiation of carcinogenesis. Thus, dietary supplementation with lycopene can serve as an alternate measure to intervene the initiation of carcinogenesis.

Deferoxamine promotes osteoblastic differentiation in human periodontal ligament cells via the nuclear factor erythroid 2-related factor-mediated antioxidant signaling pathway

BACKGROUND AND OBJECTIVE

Recently it was reported that deferoxamine (DFO), an iron chelator, stimulates bone formation from MG63 and mesenchymal stem cells, but inhibits differentiation in rat calvarial cells; however, the effect of DFO on osteoblastic differentiation in human periodontal ligament cells (hPDLCs) has not been reported. The aim of this study was to investigate the effects and the possible underlying mechanism of DFO on osteoblastic differentiation of hPDLCs.

MATERIAL AND METHODS

The effect of DFO on osteoblast differentiation was determined by the staining intensity of calcium deposits with Alizarin red and by RT-PCR analysis of the expression of osteoblastic markers. Signal transduction pathways were analyzed by western blotting.

RESULTS

DFO increased osteogenic differentiation in a concentration-dependent manner by expression of the mRNA for differentiation markers and calcium nodule formation. Exposure of hPDLCs to DFO resulted in increases in the production of reactive oxygen species and in the levels of nuclear factor erythroid 2-related factor (Nrf2) protein in nuclear extractions, as well as a dose-dependent increase in the expression of Nrf2 target genes, including glutathione (GSH), glutathione S-transferase, γ-glutamylcysteine lygase, glutathione reductase and glutathione peroxidase. Pretreatment with Nrf2 small interfering RNA, GSH depletion by buthionine sulfoximine and diethyl maleate, and with antioxidants by N-acetylcysteine and vitamin E, blocked DFO-stimulated osteoblastic differentiation. Furthermore, pretreatment with GSH depletion and antioxidants blocked DFO-induced p38 MAPK, ERK, JNK and nuclear factor-kappaB pathways.

CONCLUSION

These data indicate, for the first time, that nontoxic DFO promotes osteoblastic differentiation of hPDLCs via modulation of the Nrf2-mediated antioxidant pathway.

Antioxidative and antigenotoxic effect of vitamin E against patulin cytotoxicity and genotoxicity in HepG2 cells

Patulin (PAT) is a mycotoxin produced in fruits, mainly in apples, by certain species of Penicillium, Aspergillus, and Byssochlamys. It has been shown that PAT is cytotoxic, genotoxic, and mutagenic in different cell types. Several studies incriminate the oxidative stress as a mechanism of PAT-mediated toxicity. In this context, our aim was to investigate the protective role of Vitamin E (Vit E), an antioxidant agent, against PAT induced cytotoxicity and genotoxicity in cultured HepG2 cells. The obtained results showed that addition of Vit E in cells treated with PAT significantly reduce cell mortality induced by this toxin. In the same conditions, Vit E decreased the intracellular level of ROS, reduced PAT induced p53 expression, and reversed PAT induced DNA damage. In addition, Vit E prevented significantly the percentage of chromosome aberrations induced by PAT in HepG2 cells in a concentration dependant manner. These results suggest that Vit E, an exogenous antioxidant agent, plays an important role in defense against PAT-induced cytotoxicity and genotoxicity, which confirms the involvement of oxidative stress in the induction of DNA damage by PAT in HepG2 cells.

Role of DLC1 tumor suppressor gene and MYC oncogene in pathogenesis of human hepatocellular carcinoma: potential prospects for combined targeted therapeutics (review)

Hepatocellular carcinoma (HCC) is the third leading cause of cancer death, and its incidence is increasing worldwide in an alarming manner. The development of curative therapy for advanced and metastatic HCC is a high clinical priority. The HCC genome is complex and heterogeneous; therefore, the identification of recurrent genomic and related gene alterations is critical for developing clinical applications for diagnosis, prognosis and targeted therapy of the disease. This article focuses on recent research progress and our contribution in identifying and deciphering the role of defined genetic alterations in the pathogenesis of HCC. A significant number of genes that promote or suppress HCC cell growth have been identified at the sites of genomic reorganization. Notwithstanding the accumulation of multiple genetic alterations, highly recurrent changes on a single chromosome can alter the expression of oncogenes and tumor suppressor genes (TSGs) whose deregulation may be sufficient to drive the progression of normal hepatocytes to malignancy. A distinct and highly recurrent pattern of genomic imbalances in HCC includes the loss of DNA copy number (associated with loss of heterozygosity) of TSG-containing chromosome 8p and gain of DNA copy number or regional amplification of protooncogenes on chromosome 8q. Even though 8p is relatively small, it carries an unusually large number of TSGs, while, on the other side, several oncogenes are dispersed along 8q. Compelling evidence demonstrates that DLC1, a potent TSG on 8p, and MYC oncogene on 8q play a critical role in the pathogenesis of human HCC. Direct evidence for their role in the genesis of HCC has been obtained in a mosaic mouse model. Knockdown of DLC1 helps MYC in the induction of hepatoblast transformation in vitro, and in the development of HCC in vivo. Therapeutic interventions, which would simultaneously target signaling pathways governing both DLC1 and MYC functions in hepatocarcinogenesis, could result in progress in the treatment of liver cancer.

Persistent oxidative stress in patients with chronic active hepatitis-C infection after antiviral therapy failure

BACKGROUND/AIMS

Oxidative stress and hepatocellular pathological changes are common associations with chronic hepatitis C virus (CHC) disease. The aim of this study was to assess serum antioxidant-oxidant (Redox) balance in patients with CHC infection before and after intake of the traditional antiviral therapy (pegylated interferon α-2b and oral ribavirin).

PATIENTS AND METHODS

Blood samples from 50 biopsy-proven CHC patients, with no prior anti-viral treatment and persistently elevated serum transaminase levels for 6 months, as well as 15 age- and sex-matched healthy subjects were used for determination of the antioxidants: reduced glutathione (GSH), superoxide dismutase (SOD), α tocopherol and ascorbic acid as well as lipid peroxidation (LPO) index (malondialdehyde [MDA]). The measurements were repeated in the diseased group 25 weeks after pegylated interferon α-2b and ribavirin combination therapy.

RESULTS

Serum levels of bilirubin, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were significantly higher in CHC patients than in the control group (P < 0.05). Pretreatment serum MDA values were significantly higher in patients with CHC infection than the control group (P < 0.001), while serum antioxidant levels were significantly lower (P < 0.001). Responders (10 patients) had lower pretreatment serum levels of MDA than non-responders (35 patients) (P < 0.001). Both groups were comparable for the antioxidant serum levels. There was significant negative correlation between serum MDA and serum SOD, GSH, α tocopherol, and ascorbic acid concentrations in CHC patients. On the other hand, there was no correlation between the studied parameters and serum bilirubin, albumin, ALT, and AST.

CONCLUSIONS

Redox imbalance was detected in patients with CHC. Responders had significantly lower levels of MDA than non-responders. Serum MDA may be used as a pretreatment predictor of response to antiviral treatment in patients with CHC.

Role of reactive oxygen species in the early stages of liver regeneration in streptozotocin-induced diabetic rats

Diabetes mellitus is a risk factor for prognosis after liver resection. In previous work, we found a pro-apoptotic state in the diabetic rat liver. In this work, this was also observed 1 hour post-partial hepatectomy (PH) and resulted in a deficient regenerative response 24 hours post-PH. Treatment with insulin and/or Desferoxamine (DES) (iron chelator) or Tempol (TEM) (free radicals scavenger) was effective in preventing the liver reactive oxygen species (ROS) production induced by diabetic state. High levels of ROS play a role in hepatic lipid peroxidation in diabetes before and after PH, and lead to increased pro-apoptotic events, which contribute to a reduced regenerative response. This becomes of relevance for the potential use of antioxidants/free radical scavengers plus insulin for improvement of post-surgical recovery of diabetic patients subjected to a PH.

Problems with using the normal distribution--and ways to improve quality and efficiency of data analysis

Background

The Gaussian or normal distribution is the most established model to characterize quantitative variation of original data. Accordingly, data are summarized using the arithmetic mean and the standard deviation, by ± SD, or with the standard error of the mean, ± SEM. This, together with corresponding bars in graphical displays has become the standard to characterize variation.

Methodology/Principal Findings

Here we question the adequacy of this characterization, and of the model. The published literature provides numerous examples for which such descriptions appear inappropriate because, based on the “95% range check”, their distributions are obviously skewed. In these cases, the symmetric characterization is a poor description and may trigger wrong conclusions. To solve the problem, it is enlightening to regard causes of variation. Multiplicative causes are by far more important than additive ones, in general, and benefit from a multiplicative (or log-) normal approach. Fortunately, quite similar to the normal, the log-normal distribution can now be handled easily and characterized at the level of the original data with the help of both, a new sign, ^x/, times-divide, and notation. Analogous to ± SD, it connects the multiplicative (or geometric) mean * and the multiplicative standard deviation s* in the form * ^x/s*, that is advantageous and recommended.

Conclusions/Significance

The corresponding shift from the symmetric to the asymmetric view will substantially increase both, recognition of data distributions, and interpretation quality. It will allow for savings in sample size that can be considerable. Moreover, this is in line with ethical responsibility. Adequate models will improve concepts and theories, and provide deeper insight into science and life.

Tocotrienol-rich fraction prevents cell cycle arrest and elongates telomere length in senescent human diploid fibroblasts

This study determined the molecular mechanisms of tocotrienol-rich fraction (TRF) in preventing cellular senescence of human diploid fibroblasts (HDFs). Primary culture of HDFs at various passages were incubated with 0.5 mg/mL TRF for 24 h. Telomere shortening with decreased telomerase activity was observed in senescent HDFs while the levels of damaged DNA and number of cells in G(0)/G(1) phase were increased and S phase cells were decreased. Incubation with TRF reversed the morphology of senescent HDFs to resemble that of young cells with decreased activity of SA-β-gal, damaged DNA, and cells in G(0)/G(1) phase while cells in the S phase were increased. Elongated telomere length and restoration of telomerase activity were observed in TRF-treated senescent HDFs. These findings confirmed the ability of tocotrienol-rich fraction in preventing HDFs cellular ageing by restoring telomere length and telomerase activity, reducing damaged DNA, and reversing cell cycle arrest associated with senescence.

Alrp, a survival factor that controls the apoptotic process of regenerating liver after partial hepatectomy in rats

Augmenter of Liver Regeneration (Alrp) enhances, through unknown mechanism/s, hepatocyte proliferation only when administered to partially hepatectomized (PH) rats. Liver resection, besides stimulating hepatocyte proliferation, induces reactive oxygen species (ROS), triggering apoptosis. To clarify the role of Alrp in the process of liver regeneration, hepatocyte proliferation, apoptosis, ROS-induced parameters and morphological findings of regenerating liver were studied from PH rats Alrp-treated for 72 h after the surgery. The same parameters, evaluated on regenerating liver from albumin-treated PH rats, were used as control. The results demonstrated that Alrp administration induces the anti-apoptotic gene expression, inhibits hepatocyte apoptosis and reduces ROS-induced cell damage. These and similar data from in vitro studies and the presence of 'Alrp homologous proteins' in viruses as well as in mammals (i) allow to hypothesize that Alrp activity/ies may not be exclusive for regenerating liver and (ii) suggest the use of Alrp in the treatment of oxidative stress-related diseases.

gamma-Tocotrienol prevents oxidative stress-induced telomere shortening in human fibroblasts derived from different aged individuals

The effects of palm gamma-tocotrienol (GGT) on oxidative stress-induced cellular ageing was investigated in normal human skin fibroblast cell lines derived from different age groups; young (21-year-old, YF), middle (40-year-old, MF) and old (68-year-old, OF). Fibroblast cells were treated with gamma-tocotrienol for 24 hours before or after incubation with IC50 dose of H2O2 for 2 hours. Changes in cell viability, telomere length and telomerase activity were assessed using the MTS assay (Promega, USA), Southern blot analysis and telomere repeat amplification protocol respectively. Results showed that treatment with different concentrations of gamma-tocotrienol increased fibroblasts viability with optimum dose of 80 microM for YF and 40 microM for both MF and OF. At higher concentrations, gamma-tocotrienol treatment caused marked decrease in cell viability with IC50 value of 200 microM (YF), 300 microM (MF) and 100 microM (OF). Exposure to H2O2 decreased cell viability in dose dependent manner, shortened telomere length and reduced telomerase activity in all age groups. The IC50 of H2O2 was found to be; YF (700 microM), MF (400 microM) and OF (100 microM). Results showed that viability increased significantly (p < 0.05) when cells were treated with 80 microM and 40 microM gamma-tocotrienol prior or after H2O2-induced oxidative stress in all age groups. In YF and OF, pretreatment with gamma-tocotrienol prevented shortening of telomere length and reduction in telomerase activity. In MF, telomerase activity increased while no changes in telomere length was observed. However, post-treatment of gamma-tocotrienol did not exert any significant effects on telomere length and telomerase activity. Thus, these data suggest that gamma-tocotrienol protects against oxidative stress-induced cellular ageing by modulating the telomere length possibly via telomerase.

Dietary antioxidants in the prevention of hepatocarcinogenesis: a review

In this review, the role of dietary antioxidants in the prevention of hepatocarcinogenesis is examined. Both human and animal models are discussed. Vitamin C, vitamin E, and selenium are antioxidants that are essential in the human diet. A number of non-essential chemicals also contain antioxidant activity and are consumed in the human diet, mainly as plants or as supplements, including beta-carotene, ellagic acid, curcumin, lycopene, coenzyme Q(10), epigallocatechin gallate, N-acetyl cysteine, and resveratrol. Although some human and animal studies show protection against carcinogenesis with the consumption of higher amounts of antioxidants, many studies show no effect or an enhancement of carcinogenesis. Because of the conflicting results from these studies, it is difficult to make dietary recommendations as to whether consuming higher amounts of specific antioxidants will decrease the risk of developing hepatocellular carcinoma.

Tocopherol transfer protein sensitizes prostate cancer cells to vitamin E

Prostate cancer is a major cause of mortality in men in developed countries. It has been reported that the naturally occurring antioxidant α-tocopherol (vitamin E) attenuates prostate cancer cell proliferation in cultured cells and mouse models. We hypothesized that overexpression of the tocopherol transfer protein (TTP), a vitamin E-binding protein that regulates tocopherol status, will sensitize prostate cancer cells to the anti-proliferative actions of the vitamin. To test this notion, we manipulated the expression levels of TTP in cultured prostate cells (LNCaP, PC3, DU145, and RWPE-1) using overexpression and knockdown approaches. Treatment of cells with tocopherol caused a time- and dose-dependent inhibition of cell proliferation. Overexpression of TTP dramatically sensitized the cells to the apoptotic effects of α-tocopherol, whereas reduction ("knockdown") of TTP expression resulted in resistance to the vitamin. TTP levels also augmented the inhibitory effects of vitamin E on proliferation in semi-solid medium. The sensitizing effects of TTP were paralleled by changes in the intracellular accumulation of a fluorescent analog of vitamin E and by a reduction in intracellular levels of reactive oxygen species and were not observed when a naturally occurring, ligand binding-defective mutant of TTP was used. We conclude that TTP sensitizes prostate cancer cells to the anti-proliferative effects of vitamin E and that this activity stems from the ability of protein to increase the intracellular accumulation of the antioxidant. These observations support the notion that individual changes in the expression level or activity of TTP may determine the responsiveness of prostate cancer patients to intervention strategies that utilize vitamin E.

Vitamin E deficiency induces liver nuclear factor-κB DNA-binding activity and changes in related genes

The biological functions of vitamin E have been classically attributed to its property as a potent inhibitor of lipid peroxidation in cellular membranes. However, in 1991, Azzi's group first described that alpha-tocopherol inhibits smooth muscle cell proliferation in a protein kinase C (PKC)-dependent way, demonstrating a non-antioxidant cell signalling function for vitamin E. More recently, the capacity of alpha-tocopherol to modulate gene expression with the implication of different transcription factors, beyond its antioxidant properties, has also been established. This study was to determine the effect of vitamin E-deficiency on liver nuclear factor-kappa B (NF-kappaB) DNA-binding activity and the response of target antioxidant-defense genes and cell cycle modulators. Rats were fed either control diet or vitamin-E free diet until 60 or 90 days after birth. Vitamin E-deficiency enhanced liver DNA-binding activity of NF-kappaB [electrophoretic mobility-shift assay, (EMSA)] and up-regulated transcription of gamma-glutamylcysteine synthetase (gamma-GCSM; gamma-GCSC), cyclin D1 and cyclin E. We also showed down-regulation of p21(Waf1/Cip1) transcription. Western-blot analysis demonstrated that gamma-glutamylcysteine synthetase catalytic subunit (gamma-GCSC) and cyclin D1 showed a similar pattern to that found in the RT-PCR analysis. Moreover, chromatin immunoprecipitation (ChIP) assay demonstrated that NF-kappaB directly regulates transcription of gamma-GCS (both subunits) and cyclin D1 through the binding of NF-kappaB to the corresponding gene promoters, which was enhanced in vitamin E-deficiency. These findings show that vitamin E-deficiency induces significant molecular regulatory properties in liver cells with an altered expression of both antioxidant-defense genes and genes that control the cell cycle and demonstrate that liver NF-kappaB activation is involved in this response. Our results emphasize the importance of maintaining an adequate vitamin E consumption not only to prevent liver oxidative damage but also in modulating signal transduction.

Antitumor and antioxidant activity of protocatechualdehyde produced from Streptomyces lincolnensis M-20

We characterized the biological functions of protocatechualdehyde (PA) isolated from the butanol extract of culture supernatant from Streptomyces lincolnensis M-20. Following butanol extraction, it was purified by silica gel and Sephadex LH-20 column chromatography. PA was analyzed by Furier Transform Infrared Spectroscopy (FT-IR), Gas chromatograph-Mass Spectrometer (GC-MS), and Nuclear Magnetic Resonance (NMR). PA had potent antioxidant activity, as measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity. Antitumor activity against MCF-7 human breast cancer cells was evaluated by the 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyl tetrazolium-bromide (MTT) assay. PA treatment (0 approximately 150 muM) dose-dependently blocked apoptosis, as shown by improved cell viability and inter-nucleosomal DNA fragmentation. Our findings suggest that Streptomyces lincolnensis M-20, a lincomycin producer, also produces protocatechualdehyde.

Mutagenic and epigenetic mechanisms of zearalenone: prevention by Vitamin E

It has been suggested that zearalenone, a non-steroidal estrogenic mycotoxin produced by Fusarium graminearium, causes DNA damage. However, the mutagenic properties of this toxin are controversial. The purpose of this study was to investigate both genotoxic and epigenetic effects of zearalenone in vitro. The effects of zearalenone on unscheduled DNA synthesis (UDS), induction of chromosome aberrations and inhibition of gap junctional intercellular communication were determined using Vero cells. The results show that in Vero cells, zearalenone treatment caused a concentration-dependent increase in UDS, induced chromosome aberrations and inhibited gap junctional intercellular communication. All of these effects were either prevented or reduced by co-treatment with the antioxidant vitamin E. The results support the hypothesis that in Vero cells zearalenone-induced oxidative stress is involved in and precedes all of the studied effects.

Isolation and characterization of a putative liver progenitor population after treatment of fetal rat hepatocytes with TGF-beta

The "in vitro" establishment of a physiological model of bipotential liver progenitors would be useful for analyzing the molecular mechanisms involved in regulating growth and differentiation, as well as studying their potential role/s in liver physiology and pathology. The transforming growth factor-beta (TGF-beta) induces de-differentiation of fetal rat hepatocytes (FH), concomitant with changes in morphology. The aim of this work was to isolate and characterize this population of TGF-beta-treated fetal hepatocytes (TbetaT-FH) and test whether they can behave as liver progenitors. The TbetaT-FH isolated cell lines show high expression of Thy-1 and low expression of c-Kit. They express liver-specific proteins, such as albumin and alpha-fetoprotein, and mesenchymal markers, such as vimentin. TbetaT-FH maintain expression of the hnf3beta gene, but lose expression of hnf1beta, hnf4, and hnf6. They express c-met and show an increase in proliferation in response to HGF. Interestingly, the transdifferentiation process is coincident with changes in the expression of genes related to the oxidative metabolism. TbetaT-FH cultured in the presence of EGF + DMSO change morphology, towards epithelial cells, gaining expression of CK19 and c-Kit, markers found in hepatoblasts and bile duct cells. Furthermore, TbetaT-FH form duct-like structures when cultured on Matrigel. TbetaT-FH show also potential to revert to an hepatocyte phenotype when submitted to a long-term "in vitro" differentiation protocol towards hepatocytic lineage. In summary, our results support the hypothesis that hepatocytes can function as facultative liver stem cells and demonstrate that TGF-beta might play an essential role in the transdifferentiation process.

Studies on the genotoxic effect of beryllium chloride and the possible protective role of selenium/vitamins A, C and E

The genotoxic potential of beryllium chloride (BeCl2) was evaluated in vivo in mice using different endpoints. Chromosomal aberrations in bone marrow cells and in spermatocytes as well as sperm abnormalities were determined in the tested mice. The protective role of an orally administered drug consisting of selenium and vitamins A, C and E (selenium-ACE) was also studied. For analysis of chromosomal aberrations, both single and repeated oral treatments for a period of 3 weeks were performed. The doses used were 93.75, 187.50, 375, and 750 mg BeCl2/kg bw, which corresponds to 1/16, 1/8, 1/4, and 1/2 of the experimental LD50. BeCl2 induced a statistically significant increase in the percentage of chromosomal aberrations in both somatic and germ cells, with a dose- and time-response. The percentage of induced chromosomal aberrations was significantly reduced in all BeCl2-treated groups after oral administration of selenium-ACE. Beryllium chloride also induced a significant increase in the percentage of abnormal sperm. This percentage reached values of 9.62 +/- 0.32 and 5.56 +/- 0.31 in mice treated with the highest test dose of BeCl2 and with BeCl2+selenium-ACE, respectively, compared with 1.96 +/- 0.14 for the control. In conclusion, the results demonstrate the genotoxic effect of beryllium chloride and confirm the protective role of selenium-ACE against the genotoxicity of beryllium chloride.

Altered methionine metabolism and global DNA methylation in liver cancer: relationship with genomic instability and prognosis

Mounting evidence underlines the role of genomic hypomethylation in the generation of genomic instability (GI) and tumorigenesis, but whether DNA hypomethylation is required for hepatocellular carcinoma (HCC) development and progression remains unclear. We investigated the correlation between GI and DNA methylation, and influence of methionine metabolism deregulation on these parameters and hepatocarcinogenesis in c-Myc and c-Myc/Tgf-alpha transgenic mice and human HCCs. S-adenosyl-L-methionine/S-adenosylhomocysteine ratio and liver-specific methionine adenosyltransferase (MatI/III) progressively decreased in dysplastic and neoplastic liver lesions developed in c-Myc transgenic mice and in human HCC with better (HCCB) and poorer (HCCP) prognosis (based on patient's survival length). Deregulation of these parameters resulted in a rise of global DNA hypomethylation both in c-Myc and human liver lesions, positively correlated with GI levels in mice and humans, and inversely correlated with the length of survival of HCC patients. No changes in MATI/III and DNA methylation occurred in c-Myc/Tgf-alpha lesions and in a small human HCC subgroup with intermediate prognosis, where a proliferative activity similar to that of c-Myc HCC and HCCB was associated with low apoptosis. Upregulation of genes involved in polyamine synthesis, methionine salvage and downregulation of polyamine negative regulator OAZ1, was highest in c-Myc/Tgf-alpha HCCs and HCCP. Our results indicate that alterations in the activity of MAT/I/III, and extent of DNA hypomethylation and GI are prognostic markers for human HCC. However, a small human HCC subgroup, as c-Myc/Tgf-alpha tumors, may develop in the absence of alterations in DNA methylation.