Shengnan Liu

Arsenic induces the expressions of angiogenesis-related factors through PI3K and MAPK pathways in SV-HUC-1 human uroepithelial cells.

Arsenic, a well-established human carcinogen, can cause various types of cancers, including bladder cancer. Angiogenesis is a key event for tumor initiation. In this study, several important angiogenesis related factors, including cyclooxygenase-2 (COX-2), vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1α (HIF-1α), were up-regulated and PI3K/AKT and MAPK signal pathways were activated in human uroepithelial cell line (SV-HUC-1) treated with NaAsO2 (0, 1, 2, 4, 8 or 10μM) for 24h. Arsenite-induced HIF-1α, VEGF and COX-2 expressions were decreased by PI3K inhibitors. Blockage of the ERK1/2, p38 and JNK down-regulated the VEGF level, while ERK1/2 and p38 inhibitors were more effective than JNK in attenuating arsenite-induced COX-2 expression. HIF-1α expression was only decreased by ERK1/2 inhibitor. It was found that superoxide (O2(-)) generation was involved in arsenite-induced the activation of MAPK and PI3K pathways, which led to the HIF-1α, COX-2 and VEGF overexpressions. In conclusion, arsenite-induced COX-2, VEGF and HIF-1α expressions, mediated partially by reactive oxygen species (ROS), were regulated by MAPK and PI3K/AKT signaling pathways in human uroepithelial cells.

JNK and NADPH Oxidase Involved in Fluoride-Induced Oxidative Stress in BV-2 Microglia Cells

Excessive fluoride may cause central nervous system (CNS) dysfunction, and oxidative stress is a recognized mode of action of fluoride toxicity. In CNS, activated microglial cells can release more reactive oxygen species (ROS), and NADPH oxidase (NOX) is the major enzyme for the production of extracellular superoxide in microglia. ROS have been characterized as an important secondary messenger and modulator for various mammalian intracellular signaling pathways, including the MAPK pathways. In this study we examined ROS production and TNF-α, IL-1β inflammatory cytokines releasing, and the expression of MAPKs in BV-2 microglia cells treated with fluoride. We found that fluoride increased JNK phosphorylation level of BV-2 cells and pretreatment with JNK inhibitor SP600125 markedly reduced the levels of intracellular O2 ·− and NO. NOX inhibitor apocynin and iNOS inhibitor SMT dramatically decreased NaF-induced ROS and NO generations, respectively. Antioxidant melatonin (MEL) resulted in a reduction in JNK phosphorylation in fluoride-stimulated BV-2 microglia. The results confirmed that NOX and iNOS played an important role in fluoride inducing oxidative stress and NO production and JNK took part in the oxidative stress induced by fluoride and meanwhile also could be activated by ROS in fluoride-treated BV-2 cells.

Arsenic induced overexpression of inflammatory cytokines based on the human urothelial cell model in vitro and urinary secretion of individuals chronically exposed to arsenic.

Chronic persistent inflammation could play an important role in the pathogenesis of some malignancies, and inflammation is a critical factor for bladder cancer development. In this study, we measured urine levels of transforming growth factor-α (TGF-α), tumor necrosis factor-α (TNF-α), and IL-8 in arsenic exposure workers and expressions of inflammatory cytokines in human urothelial cells in vivo and in vitro. We found the concentrations of IL-8, TNF-α, and TGF-α presented in urine were significantly elevated in the high urinary arsenic workers compared with the low urinary arsenic workers. Multiple regression analysis showed that the urinary IL-8 level was significantly positively associated with urinary iAs concentration after adjusting for the confounding effects of age, employed years, body mass index (BMI), smoking, alcohol, and seafood consumption in recent 3 days. Urinary TNF-α and TGF-α levels were also significantly positively associated with urinary iAs concentration, and SMI. TGF-α level was negatively associated with age after adjusting for the confounding effects. Consistent with the results in vivo, mRNA expressions of TNF-α, TGF-α, and IL-8 and protein expressions of TGF-α, TGF-β1, and IL-8 were significantly elevated in SV-HUC-1 cells after exposure to lower concentrations of arsenite for 24h as compared to the control group. These data indicated that arsenic increased the secretion of inflammatory factors and IL-8, TNF-α, and TGF-α expression may be a useful biomarker of the effect of arsenic exposure.

Maize Purple Plant Pigment Protects Against Fluoride-Induced Oxidative Damage of Liver and Kidney in Rats

Anthocyanins are polyphenols and well known for their biological antioxidative benefits. Maize purple plant pigment (MPPP) extracted and separated from maize purple plant is rich in anthocyanins. In the present study, MPPP was used to alleviate the adverse effects generated by fluoride on liver and kidney in rats. The results showed that the ultrastructure of the liver and kidney in fluoride treated rats displayed shrinkage of nuclear and cell volume, swollen mitochondria and endoplasmic reticulum and vacuols formation in the liver and kidney cells. MPPP significantly attenuated these fluoride-induced pathological changes. The MDA levels in serum and liver tissue of fluoride alone treated group were significantly higher than those of the control group (p < 0.05). The presence of 5 g/kg MPPP in the diet reduced the elevation of MDA levels in blood and liver, and increased the SOD and GSH-Px activities in kidney and GSH level in liver and kidney compared with the fluoride alone treated group (p < 0.05). In addition, MPPP alleviated the decrease of Bcl-2 protein expression and the increase of Bax protein expression induced by fluoride. This study demonstrated the protective role of MPPP against fluoride-induced oxidative stress in liver and kidney of rats.

DMA(V) in Drinking Water Activated NF-κB Signal Pathway and Increased TGF-β and IL-1β Expressions in Bladder Epithelial Cells of Rats.

Dimethylarsinic acid (DMAV) is the main product of arsenic methylation metabolism in vivo and is rat bladder carcinogen and tumor promoting agent. In this study, we measured the expressions of mRNA and proteins of NF-κB pathway members, IKKα, IKKβ, p65, and p50 in rat bladder epithelium by qRT-PCR and immunohistochemical analysis after rats received drinking water containing 100 and 200 ppm DMAV for 10 weeks. Transforming growth factor-β (TGF-β) immunoexpression in rat bladder epithelium and urine level of IL-1β also were determined. We found that DMAV dramatically increased the mRNA levels of NF-κB p50 and IKKα in the bladder epithelium of rats compared to the control group. Immunohistochemical examinations showed that DMAV increased immunoreactivities of IKKα, IKKβ, and phospho-NF-κB p50 in the cytoplasm and phospho-NF-κB p50 and p65 in nucleus of rat urothelial cells. In addition, DMAV treated rats exhibited significantly increased inflammatory factor TGF-β immunoreactivity in bladder epithelium and IL-1β secretion in urine. These data suggest that DMAV could activate NF-κB signal pathway and increase TGF-β and IL-1β expressions in bladder epithelial cells of rats.

Urinary VEGF and PGE2 levels and the association with arsenical metabolites in copper-smelting workers

Objectives To examine vascular endothelial growth factor (VEGF) and PGE2 levels in urine from the copper smelting workers exposed to arsenic and analyse the relationships between urinary VEGF or PGE2 level and arsenical metabolites. Methods The study was conducted in a group of 106 copper-smelting male workers. Information about each subject was obtained by questionnaire, inorganic As (iAs), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), VEGF and prostaglandin E2 (PGE2) in urine were determined. Standing height, body weight, and blood pressure were measured. Results According to the urine arsenic levels, participants were separated into three groups: Group 1: urine total arsenic <35 mg/L, Group 2: 35–100 mg/L, and Group 3: >100 mg/L. The median levels of urinary VEGF and PGE2 in Groups 1, 2 and 3 were 10.57 and 1032.0 pg/mL, 24.39 and 1060.9 pg/mL, and 49.0 and 1330.4 pg/mL, respectively. Urinary VEGF levels were positive associated with arsenical metabolites (iAs, MMA, DMA and TAs). Additionally, urinary VEGF and PGE2 levels were all correlated positively with the urinary MMA% (r=0.221, p=0.026 and r=0.206, p=0.037). While urinary VEGF was negatively with DMA% and secondary methylation index (r=−0.242, p=0.014 and r=−0.214, p=0.030, respectively). Conclusions Urinary VEGF and PGE2 levels increased in arsenic exposure copper smelting workers, and urinary VEGF levels are well associated with the urinary arsenicals. This finding may provide useful information for developing measurement, prevention and treatment of damage induced by arsenic in the future.