Shizukaol C alleviates trimethylamine oxide-induced inflammation through activating Keap1-Nrf2-GSTpi pathway in vascular smooth muscle cell.

BACKGROUND: Cardiovascular disease is one of the main causes of global mortality, and there is an urgent need for effective treatment strategies. Gut microbiota-dependent metabolite trimethylamine-N-oxide (TMAO) promotes the development of cardiovascular diseases, and shizukaol C, a natural sesquiterpene isolated from Chloranthus multistachys with various biological activities, might exhibit beneficial role in preventing TMAO-induced vascular inflammation. PURPOSE: The purpose of this study was to investigate the anti-inflammatory effects and the underlying mechanisms of shizukaol C on TMAO-induced vascular inflammation. METHODS: The effect and underlying mechanism of shizukaol C on TMAO-induced adhesion molecules expression, bone marrow-derived macrophages (BMDM) adhesion to VSMC were evaluated by western blot, cell adhesion assay, co-immunoprecipitation, immunofluorescence assay, and quantitative Real-Time PCR, respectively. To verify the role of shizukaol C in vivo, TMAO-induced vascular inflammation model were established using guidewire-induced injury on mice carotid artery. Changes in the intima area and the expression of GSTpi, VCAM-1, CD68 were examined using haematoxylin-eosin staining, and immunofluorescence assay. RESULTS: Our data demonstrated that shizukaol C significantly suppressed TMAO-induced adhesion molecule expression and the bone marrow-derived macrophages (BMDM) adhesion in vascular smooth muscle cells (VSMC). Mechanically, shizukaol C inhibited TMAO-induced c-Jun N-terminal kinase (JNK)-nuclear factor-kappa B (NF-κB)/p65 activation, and the JNK inhibition was dependent on the shizukaol C-mediated glutathione-S-transferase pi (GSTpi) expression. By further molecular docking and protein-binding analysis, we demonstrated that shizukaol C directly binds to Keap1 to induce Nrf2 nuclear translocation and upregulated GSTpi expression. Consistently, our in vivo experiment showed that shizukaol C elevated the expression level of GSTpi in carotid arteries and alleviates TMAO-induced vascular inflammation. CONCLUSION: Shizukaol C exerts anti-inflammatory effects in TMAO-treated VSMC by targeting Keap1 and activating Nrf2-GSTpi signaling and resultantly inhibits the downstream JNK-NF-κB/p65 activation and VSMC adhesion, and alleviates TMAO-induced vascular inflammation in vivo, suggesting that shizukaol C may be a potential drug for treating TMAO-induced vascular diseases.

Soy phytoestrogens modify DNA methylation of GSTP1, RASSF1A, EPH2 and BRCA1 promoter in prostate cancer cells.

BACKGROUND: The aim of this study was to determine the effects of soy phytoestrogens on the methylation of promoter genes in prostate tumors. The incidence of prostate cancer in Asia is thirty percent lower than in Western countries. Since soy phytoestrogens represent a large portion of the Asian diet, evidence suggests their protective effect against prostate cancer. MATERIALS AND METHODS: In three human prostate cancer cell lines, methylation-specific-PCR was used to determine the effect of soy isoflavones (genistein and daidzein), compared to known demethylating agent 5-azacytidine as control in the promoter regions of glutathione S-transferase P1 (GSTP1), Ras association domain family 1 (RASSF1A), ephrin B2 (EPHB2) and breast cancer 1 (BRCA1) genes. In parallel, immunohistochemistry was used to assess the effects of genistein, daidzein and 5-azacytidine treatment on the corresponding protein expression. RESULTS: All studied promoters, with the exception of that for BRCA1, were strongly methylated without treatment. After treatment by phytoestrogens, demethylation of GSTP1 and EPHB2 promoter regions was observed and an increase in their protein expression was demonstrated by immunohistochemistry. CONCLUSION: Epigenetic modifications of DNA, such as the promoter CpG island demethylation of tumor suppressor genes, might be related to the protective effect of soy on prostate cancer.

Modulation of human glutathione s-transferases by polyphenon e intervention.

PURPOSE: Green tea consumption has been associated with decreased risk of certain types of cancers in humans. Induction of detoxification enzymes has been suggested as one of the biochemical mechanisms responsible for the cancer-preventive effect of green tea. We conducted this clinical study to determine the effect of repeated green tea polyphenol administration on a major group of detoxification enzymes, glutathione S-transferases (GST). METHODS: A total of 42 healthy volunteers underwent a 4-week washout period by refraining from tea or tea-related products. At the end of the washout period, a fasting blood sample was collected, and plasma and lymphocytes were isolated for assessment of GST activity and level. Following the baseline evaluation, study participants underwent 4 weeks of green tea polyphenol intervention in the form of a standardized Polyphenon E preparation at a dose that contains 800 mg epigallocatechin gallate (EGCG) once a day. Polyphenon E was taken on an empty stomach to optimize the oral bioavailability of EGCG. Upon completion of the intervention, samples were collected for postintervention GST assessment. RESULTS: Four weeks of Polyphenon E intervention enhanced the GST activity in blood lymphocytes from 30.7 +/- 12.2 to 35.1 +/- 14.3 nmol/min/mg protein, P = 0.058. Analysis based on baseline activity showed that a statistically significant increase (80%, P = 0.004) in GST activity was observed in individuals with baseline activity in the lowest tertile, whereas a statistically significant decrease (20%, P = 0.02) in GST activity was observed in the highest tertile. In addition, Polyphenon E intervention significantly increased the GST-pi level in blood lymphocytes from 2,252.9 +/- 734.2 to 2,634.4 +/- 1,138.3 ng/mg protein, P = 0.035. Analysis based on baseline level showed that this increase was only significant (P = 0.003) in individuals with baseline level in the lowest tertile, with a mean increase of 80%. Repeated Polyphenon E administration had minimal effects on lymphocyte GST-mu and plasma GST-alpha levels. There was a small but statistically significant decrease (8%, P = 0.003) in plasma GST-alpha levels in the highest tertile. CONCLUSIONS: We conclude that 4 weeks of Polyphenon E administration resulted in differential effects on GST activity and level based on baseline enzyme activity/level, with GST activity and GST-pi level increased significantly in individuals with low baseline enzyme activity/level. This suggests that green tea polyphenol intervention may enhance the detoxification of carcinogens in individuals with low baseline detoxification capacity.

Dietary selenium intake and genetic polymorphisms of the GSTP1 and p53 genes on the risk of esophageal squamous cell carcinoma.

Few studies have assessed potential effect modifications by polymorphisms of susceptibility genes on the association between selenium intake and esophageal squamous cell carcinoma (ESCC). We studied the joint effects of dietary selenium and the GSTP1 and p53 polymorphisms on ESCC risk in a population-based case-control study with 218 ESCC cases and 415 controls in Taixing City, China. Dietary selenium intake was estimated from a food frequency questionnaire with 97 food items. GSTP1 and p53 polymorphisms were detected by RFLP-PCR assays. Logistic regression analyses were done to estimate odds ratios (OR) and 95% confidence intervals (95% CI). Reduced ESCC risk was observed among individuals in the highest quartile of dietary selenium intake (adjusted OR, 0.31; 95% CI, 0.13-0.70) with a dose-dependent gradient (P(trend) = 0.01). The p53 Pro/Pro genotype was associated with increased risk of ESCC compared with the Arg/Arg genotype (adjusted OR, 2.02; 95% CI, 1.19-3.42). When combined with selenium consumption, an obvious increased risk was observed among individuals with the p53 Pro/Pro or GSTP1 Ile/Ile genotype with adjusted ORs of 3.19 (95% CI, 1.74-5.84) and 1.90 (95% CI, 1.03-3.51), respectively. Among smokers and alcohol drinkers, elevation of ESCC risk was more prominent among p53 Pro/Pro individuals who consumed a low level of dietary selenium (adjusted OR, 3.59; 95% CI, 1.49-8.66 for smokers and 6.19; 95% CI, 1.83-20.9 for drinkers). Our study suggests that the effect of dietary selenium on the risk of ESCC may be modulated by tobacco smoking, alcohol drinking, and p53 Pro/Pro and GSTP1 Ile/Ile genotypes.