PFOS-elicited metabolic perturbation in liver and fatty acid metabolites in testis of adult mice.

Introduction: Multiple factors can contribute to sub-fecundity, including genetics, lifestyle, and environmental contaminants. PFASs are characterized as "forever chemicals" due to their ubiquitous contamination and their persistence in the environment, wildlife, and humans. Numerous studies have demonstrated that PFAS exposure adversely affects multiple bodily functions, including liver metabolism and gonadal function. It is unclear, however, how the disruption of hepatic fatty acid metabolism affects testicular function. Methods: In this study, male mice were administered 0.3 and 3 µg/g body weight of PFOS for 21 days. Results: Our data showed that PFOS exposure caused hepatic steatosis, as evidenced by significant increases in triglyceride levels, expression of ATP-citrate lyase, and fatty acid synthase, as well as fasting insulin levels. PFOS perturbed the expression levels of hepatokines, of which fibroblast growth factor-21 (Fgf-21), leukocyte cell-derived chemotaxin-2 (Lect-2), and retinol-binding protein-4 (Rbp-4) were significantly reduced, whereas angiopoietin-like 4 (Angptl4) was noticeably increased. While Rbp-4 and Fgf-21 are known to contribute to spermatogenesis and testosterone synthesis. In PFOS-exposed groups, testicular ATP, and testosterone decreased significantly with a significant increase in the expression of peroxisome proliferator-activated receptor-coactivator 1α. Mass spectrophotometry imaging revealed the localization of PFOS in testes, along with significant increases in fatty acid metabolites. These included arachidonic acid, dihomo-α-linolenic acid, dihomo-γ-linolenic acid, oxidized ceramide, diacylglycerol, phosphatidylcholine, and phosphatidylethanolamine, which are associated with inflammation and post-testicular causes of infertility. Discussion: This study revealed potential links between PFOS-elicited changes in hepatic metabolism and their impacts on testicular biology. This study provides insights into alternative targets elicited by PFOS that can be used to develop diagnostic and therapeutic strategies for improving testicular dysfunction.

Cadmium Disrupted ER Ca2+ Homeostasis by Inhibiting SERCA2 Expression and Activity to Induce Apoptosis in Renal Proximal Tubular Cells.

Cadmium (Cd2+) exposure induces chronic kidney disease and renal cancers, which originate from injury and cancerization of renal tubular cells. Previous studies have shown that Cd2+ induced cytotoxicity by disrupting the intracellular Ca2+ homeostasis that is physically regulated by the endoplasmic reticulum (ER) Ca2+ store. However, the molecular mechanism of ER Ca2+ homeostasis in Cd2+-induced nephrotoxicity remains unclear. In this study, our results firstly revealed that the activation of calcium-sensing receptor (CaSR) by NPS R-467 could protect against Cd2+ exposure-induced cytotoxicity of mouse renal tubular cells (mRTEC) by restoring ER Ca2+ homeostasis through the ER Ca2+ reuptake channel sarco/endoplasmic reticulum Ca2+-ATPase (SERCA). Cd2+-induced ER stress and cell apoptosis were effectively abrogated by SERCA agonist CDN1163 and SERCA2 overexpression. In addition, in vivo, and in vitro results proved that Cd2+ reduced the expressions of SERCA2 and its activity regulator phosphorylation phospholamban (p-PLB) in renal tubular cells. Cd2+-induced SERCA2 degradation was suppressed by the treatment of proteasome inhibitor MG132, which suggested that Cd2+ reduced SERCA2 protein stability by promoting the proteasomal protein degradation pathway. These results suggested that SERCA2 played pivotal roles in Cd2+-induced ER Ca2+ imbalance and stress to contribute to apoptosis of renal tubular cells, and the proteasomal pathway was involved in regulating SERCA2 stability. Our results proposed a new therapeutic approach targeting SERCA2 and associated proteasome that might protect against Cd2+-induced cytotoxicity and renal injury.

Identification and characterization of a membrane receptor that binds to human STC1.

Stanniocalcin-1 (STC1) is a hypocalcemic hormone originally identified in bony fishes. The mammalian homolog is found to be involved in inflammation and carcinogenesis, among other physiological functions. In this study, we used the TriCEPS-based ligand-receptor methodology to identify the putative binding proteins of human STC1 (hSTC1) in the human leukemia monocytic cell line, ThP-1. LC-MS/MS analysis of peptides from shortlisted hSTC1-binding proteins detected 32 peptides that belong to IGF2/MPRI. Surface plasmon resonance assay demonstrated that hSTC1 binds to immobilized IGF2R/MPRI with high affinity (10-20 nM) and capacity (Rmax 70-100%). The receptor binding data are comparable with those of (CREG) cellular repressor of E1A-stimulated gene a known ligand of IGF2R/MPRI, with Rmax of 75-80% and affinity values of 1-2 nM. The surface plasmon resonance competitive assays showed CREG competed with hSTC1 in binding to IGF2R/MPRI. The biological effects of hSTC1 on ThP-1 cells were demonstrated via IGF2R/MPRI to significantly reduce secreted levels of IL-1ß. This is the first study to reveal the high-affinity binding of hSTC1 to the membrane receptor IGF2R/MPRI.

Cadmium induces epithelial-mesenchymal transition and migration of renal cancer cells by increasing PGE2 through a cAMP/PKA-COX2 dependent mechanism.

Environmental or occupational exposure of Cadmium (Cd) is concerned to be a threat to human health. The kidney is main target of Cd accumulation, which increases the risk of renal cell carcinoma (RCC). In addition, low content of Cd had been determined in kidney cancer, however, the roles of presence of Cd in renal tumors progression are still unclear. The present study is proposed to determine the effect of low-dose Cd exposure on the renal cancer cells and aimed to clarify the underlying mechanisms. The cell viability, cytotoxicity, and the migratory effect of low-dose Cd on the renal cancer cells were detected. Moreover, the roles of reactive oxygen species (ROS), Ca2+, and cyclic AMP (cAMP)/protein kinase A (PKA)-cyclooxygenase2 (COX2) signaling, as well as COX2 catalytic product prostaglandin E2 (PGE2) on cell migration and invasion were identified. Our results suggested that low dose Cd exposure promoted migration of renal cancer Caki-1 cells, which was not dependent on Cd-induced ROS and intracellular Ca2+ levels. Cd exposure induced cAMP/PKA-COX2, which mediated cell migration and invasion, and decreased expressions of epithelial-mesenchymal transition (EMT) marker, E-cadherin, but increased expressions of N-cadherin and Vimentin. Moreover, Cd-induced secretion of PGE2 feedback on activation of cAMP/PKA-COX2 signaling, also promoted EMT, migration and invasion of renal cancer Caki-1 cells. This study might contribute to understanding of the mechanism of Cd-induce progression of renal cancer and future studies on the prevention and therapy of renal cell carcinomas.

Genome-wide analysis of MicroRNA-messenger RNA interactome in ex-vivo gill filaments, Anguilla japonica.

BACKGROUND: Gills of euryhaline fishes possess great physiological and structural plasticity to adapt to large changes in external osmolality and to participate in ion uptake/excretion, which is essential for the re-establishment of fluid and electrolyte homeostasis. The osmoregulatory plasticity of gills provides an excellent model to study the role of microRNAs (miRs) in adaptive osmotic responses. The present study is to characterize an ex-vivo gill filament culture and using omics approach, to decipher the interaction between tonicity-responsive miRs and gene targets, in orchestrating the osmotic stress-induced responses. RESULTS: Ex-vivo gill filament culture was exposed to Leibovitz's L-15 medium (300 mOsmol l- 1) or the medium with an adjusted osmolality of 600 mOsmol l- 1 for 4, 8 and 24 h. Hypertonic responsive genes, including osmotic stress transcriptional factor, Na+/Cl--taurine transporter, Na+/H+ exchange regulatory cofactor, cystic fibrosis transmembrane regulator, inward rectifying K+ channel, Na+/K+-ATPase, and calcium-transporting ATPase were significantly upregulated, while the hypo-osmotic gene, V-type proton ATPase was downregulated. The data illustrated that the ex-vivo gill filament culture exhibited distinctive responses to hyperosmotic challenge. In the hyperosmotic treatment, four key factors (i.e. drosha RNase III endonuclease, exportin-5, dicer ribonuclease III and argonaute-2) involved in miR biogenesis were dysregulated (P < 0.05). Transcriptome and miR-sequencing of gill filament samples at 4 and 8 h were conducted and two downregulated miRs, miR-29b-3p and miR-200b-3p were identified. An inhibition of miR-29b-3p and miR-200b-3p in primary gill cell culture led to an upregulation of 100 and 93 gene transcripts, respectively. Commonly upregulated gene transcripts from the hyperosmotic experiments and miR-inhibition studies, were overlaid, in which two miR-29b-3p target-genes [Krueppel-like factor 4 (klf4), Homeobox protein Meis2] and one miR-200b-3p target-gene (slc17a5) were identified. Integrated miR-mRNA-omics analysis revealed the specific binding of miR-29b-3p on Klf4 and miR-200b-3p on slc17a5. The target-genes are known to regulate differentiation of gill ionocytes and cellular osmolality. CONCLUSIONS: In this study, we have characterized the hypo-osmoregulatory responses and unraveled the modulation of miR-biogenesis factors/the dysregulation of miRs, using ex-vivo gill filament culture. MicroRNA-messenger RNA interactome analysis of miR-29b-3p and miR-200b-3p revealed the gene targets are essential for osmotic stress responses.

Comparative Analysis of PFOS and PFOA Toxicity on Sertoli Cells.

Perfluoroalkyl chemicals induce male reproductive toxicity. Current evidence showed the effects of the chemical exposure on the deterioration of testicular functions, and reduction in epididymal sperm counts. Previous studies showed that PFOA and PFOS displayed a high correlation with each other in seminal plasma levels, but induced different effects on semen variables. In this study, we focused on the comparative toxicity analysis of PFOA and PFOS, using a rat primary Sertoli cell model. Our transcriptomic data showed that PFOA and PFOS treatments (40 µM) perturbed global gene expression. While PFOS induced higher toxicity in affecting cytoskeleton signaling, Sertoli cell-cell junction, and inflammation, underlined by Ingenuity pathway analysis. Immunocytochemical staining revealed that PFOS treatment (40 and 80 µM) induced truncated actin filament and disorganized bundled configuration in the cell cytoplasm. Moreover, disorganized distribution of N-cadherin (N-cad) and ß-catenin (ß-cat), and defragmentation of ZO-1 at the Sertoli cell-cell interface was evident. At 80 µM of PFOS, cytoplasmic distribution of N-cad, ß-cat, and ZO-1 were observed. We then examined whether resveratrol, a polyphenol antioxidant, was able to protect the cells from PFOS toxicity. The pretreatment of Sertoli cells with 10 µM resveratrol prevented the formation of truncated actin filament and dis-localization of ß-cat. Western blot analysis showed that Res pretreatment increased the levels of basal ES proteins (N-cad and ß-cat), tight junction proteins (ZO-1 and occludin), and gap junction protein, versus control.

The roles of calcium-sensing receptor (CaSR) in heavy metals-induced nephrotoxicity.

The kidney is a vital organ responsible for regulating water, electrolyte and acid-base balance as well as eliminating toxic substances from the blood in the body. Exposure of humans to heavy metals in their natural and occupational environments, foods, water, and drugs has serious implications on the kidney's health. The accumulation of heavy metals in the kidney has been linked to acute or chronic renal injury, kidney stones or even renal cancer, at the expense of expensive treatment options. Therefore, unearthing novel biomarkers and potential therapeutic agents or targets against kidney injury for efficient treatment are imperative. The calcium-sensing receptor (CaSR), a G-protein-coupled receptor (GPCR) is typically expressed in the parathyroid glands and renal tubules. It modulates parathyroid hormone secretion according to the serum calcium (Ca2+) concentration. In the kidney, it modulates electrolyte and water excretion by regulating the function of diverse tubular segments. Notably, CaSR lowers passive and active Ca2+ reabsorption in distal tubules, which facilitates phosphate reabsorption in proximal tubules and stimulates proton and water excretion in collecting ducts. Moreover, at the cellular level, modulation of the CaSR regulates cytosolic Ca2+ levels, reactive oxygen species (ROS) generation and the mitogen-activated protein kinase (MAPK) signaling cascades as well as autophagy and the suppression of apoptosis, an effect predominantly triggered by heavy metals. In this regard, we present a review on the CaSR at the cellular level and its potential as a therapeutic target for the development of new and efficient drugs against heavy metals-induced nephrotoxicity.

Transcriptomic and methylomic analysis reveal the toxicological effect of 2,3,7,8-Tetrachlorodibenzodioxin on human embryonic stem cell.

Cumulating epidemiological studies demonstrated that environmental exposure to endocrine disrupting chemicals (EDCs) during the early stages of fetal development is associated with the increase in disease susceptibility in later life. The fetal developmental plasticity is considered as a protective mechanism against an undesirable prenatal environment. Dioxin is one of the environmental contaminants and is considered a diabetogenic factor. Experimental animal and human epidemiological studies have revealed that dioxin exposure was associated with insulin resistance and altered beta cell function. But the effect of dioxin exposure in early stage of fetal development is still largely unknown. In this report, we used the human embryonic stem cell (hESC) line, VAL-3, as a model, together with Methyl-CpG Binding Domain (MBD) protein-enriched genome sequencing and transcriptome sequencing (RNA-seq), in order to determine the dynamic changes of the epigenetic landscape and transcriptional dysregulation in hESC upon dioxin exposure. The bioinformatics analyses including the Database for Annotation, Visualization and Integrated Discovery (DAVID) analysis and Ingenuity Pathway Analysis (IPA) highlighted the predisposed neural, hepatic, cardiac and metabolic toxicological effects of dioxin during the fetal development.

Activation of Ca2+-sensing receptor as a protective pathway to reduce Cadmium-induced cytotoxicity in renal proximal tubular cells.

Cadmium (Cd), as an extremely toxic metal could accumulate in kidney and induce renal injury. Previous studies have proved that Cd impact on renal cell proliferation, autophagy and apoptosis, but the detoxification drugs and the functional mechanism are still in study. In this study, we used mouse renal tubular epithelial cells (mRTECs) to clarify Cd-induced toxicity and signaling pathways. Moreover, we proposed to elucidate the prevent effect of activation of Ca2+ sensing receptor (CaSR) by Calcimimetic (R-467) on Cd-induced cytotoxicity and underlying mechanisms. Cd induced intracellular Ca2+ elevation through phospholipase C-inositol 1, 4, 5-trisphosphate (PLC) followed stimulating p38 mitogen-activated protein kinases (MAPK) activation and suppressing extracellular signal-regulated kinase (ERK) activation, which leaded to increase apoptotic cell death and inhibit cell proliferation. Cd induced p38 activation also contribute to autophagic flux inhibition that aggravated Cd induced apoptosis. R-467 reinstated Cd-induced elevation of intracellular Ca2+ and apoptosis, and it also increased cell proliferation and restored autophagic flux by switching p38 to ERK pathway. The identification of the activation of CaSR-mediated protective pathway in renal cells sheds light on a possible cellular protective mechanism against Cd-induced kidney injury.

Transcriptome sequencing reveals prenatal PFOS exposure on liver disorders.

Perfluorooctane sulfonate (PFOS), a hepatic toxicant and a potential hepatocarcinogen, is commonly used in industrial products. The widespread contamination of PFOS in human maternal and cord blood has raised concerns about its potential risks to the fetus. It is believed that adverse environmental exposure during the critical period of embryo development can have long-lasting consequences in later life. In this report, we used transcriptome sequencing, followed by bioinformatics analysis, to elucidate the potential hepatotoxic and hepatocarcinogenic effects of prenatal PFOS exposure in the fetus. Our results demonstrated that prenatal PFOS exposure could activate the synthesis and metabolism of fatty acids and lipids, leading to liver damage and interference with liver development in the fetus. In addition, a number of cancer-promoting signaling pathways, including Wnt/ß-catenin, Rac, and TGF-ß, were found to be activated in the fetal liver. More importantly, hepatic transaminase activity, including aspartate aminotransferase and alanine transaminase activity, was induced in the liver of mice offspring after prenatal PFOS exposure. For the first time, our results demonstrate that the hepatotoxic effects of prenatal exposure to PFOS may predispose to a long-term liver disorder in the offspring.

Ginsenoside-Rb1 targets chemotherapy-resistant ovarian cancer stem cells via simultaneous inhibition of Wnt/ß-catenin signaling and epithelial-to-mesenchymal transition.

Chemoresistance is a major clinical problem compromising the successful treatment of cancer. One exciting approach is the eradication of cancer stem/tumor-initiating cells (jointly CSCs), which account for tumor initiation, progression, and drug resistance. Here we show for the first time, with mechanism-based evidence, that ginsenoside-Rb1, a natural saponin isolated from the rhizome of Panax quinquefolius and notoginseng, exhibits potent cytotoxicity on CSCs. Rb1 and its metabolite compound K could effectively suppress CSC self-renewal without regrowth. Rb1 and compound K treatment also sensitized the CSCs to clinically relevant doses of cisplatin and paclitaxel. These effects were associated with the Wnt/ß-catenin signaling pathway by downregulating ß-catenin/T-cell factor-dependent transcription and expression of its target genes ATP-binding cassette G2 and P-glycoprotein. We also identified reversal of epithelial-to-mesenchymal transition as a new player in the Rb1 and compound K-mediated inhibition of CSCs. Rb1 and compound K treatment also inhibited the self-renewal of CSCs derived from ovarian carcinoma patients as well as in xenograft tumor model. Moreover, we did not observe toxicity in response to doses of Rb1 and compound K that produced an anti-CSC effect. Therefore, Rb1 should be explored further as a promising nutraceutical prototype of treating refractory tumors.

Pathogenesis of POLR1C-dependent Type 3 Treacher Collins Syndrome revealed by a zebrafish model.

Treacher Collins Syndrome (TCS) is a rare congenital birth disorder (1 in 50,000 live births) characterized by severe craniofacial defects, including the downward slanting palpebral fissures, hypoplasia of the facial bones, and cleft palate (CP). Over 90% of patients with TCS have a mutation in the TCOF1 gene. However, some patients exhibit mutations in two new causative genes, POLR1C and POLR1D, which encode subunits of RNA polymerases I and III, that affect ribosome biogenesis. In this study, we examine the role of POLR1C in TCS using zebrafish as a model system. Our data confirmed that polr1c is highly expressed in the facial region, and dysfunction of this gene by knockdown or knock-out resulted in mis-expression of neural crest cells during early development that leads to TCS phenotype. Next generation sequencing and bioinformatics analysis of the polr1c mutants further demonstrated the up-regulated p53 pathway and predicted skeletal disorders. Lastly, we partially rescued the TCS facial phenotype in the background of p53 mutants, which supported the hypothesis that POLR1C-dependent type 3 TCS is associated with the p53 pathway.

Transcriptomic responses of corpuscle of Stannius gland of Japanese eels (Anguilla japonica) to changes in water salinity.

Physiological studies of a unique endocrine gland in fish, named corpuscles of Stannius (CS), described a Ca2(+)-regulatory function for this gland mediated by stanniocalcin-1, a hypocalcemic polypeptide hormone. However, to date, the endocrine functions of the glands have not been completely elucidated.We hypothesized that other unidentified active principles in the glands are involved in the regulation of plasma ion (Na(+), Ca2(+)) and/or blood pressure. In this study, transcriptome sequencing of CS glands was performed using Japanese eels (Anguilla japonica) adapted to freshwater (FW) or seawater (SW) to reveal the presence and differential expression of genes encoding proteins related to the ion-osmoregulatory and pressor functions. We acquired a total of 14.1 Mb and 12.1 Mb quality-trimmed reads from the CS glands collected from FW and SW adapted eels, respectively. The de novo assembly resulted in 9254 annotated genes. Among them, 475 genes were differentially expressed with 357 up- and 118 down-regulated in the SW group. Gene ontology analysis further demonstrated the presence of natriuresis and pressor related genes. In summary, ours is the first study using high-throughput sequencing to identify gene targets that could explain the physiological importance of the CS glands.

Methionine oxidation in albumin by fine haze particulate matter: an in vitro and in vivo study.

The potential effects of inhaled fine particulate matter (PM2.5), found in haze episodes, on the oxidation of the proteins in the lungs are not well understood. We investigated the effects of PM2.5 from haze episodes on protein oxidation. PM2.5 was collected from the air pollution in Beijing (BJ), Xian (XA), Xiamen (XM) and Hong Kong (HK) during a period of intensive haze episodes. The chemical characteristics of these samples and their effects on albumin oxidation were investigated. The levels of PM2.5 in BJ and XA were 4-6 times higher than in XM and HK. The concentrations of the polycyclic aromatic hydrocarbons (PAHs) components of the PM2.5 from BJ and XA were 10 times higher than those found in XM and HK. The haze PM2.5 increased oxidative stress. Addition of PM2.5 samples collected from haze episodes to albumin in vitro resulted in oxidation of methionine moieties; nasal instillation of PM2.5 suspensions in mice resulted in oxidation of methionine in the albumin in the bronchoalveolar lavage fluid. The methionine moieties participate in peptide chain crosslinking, and methionine oxidation in the albumin could be attributed to the PAH compounds. Our findings may be helpful in explaining the potential respiratory effects during haze episodes.

Zebrafish transforming growth factor-ß-stimulated clone 22 domain 3 (TSC22D3) plays critical roles in Bmp-dependent dorsoventral patterning via two deubiquitylating enzymes Usp15 and Otud4.

BACKGROUND: Osmotic stress transcription factor 1/transforming growth factor-ß-stimulated clone 22 domain 3 (Ostf1/Tsc22d3) is a transcription factor that plays an osmoregulatory role in euryhaline fishes. Its mRNA and protein levels are up-regulated under hyperosmotic stress. However, its osmoregulatory and developmental functions have not been studied in any stenohaline freshwater fishes. Zebrafish is an excellent model to perform such study to unfold the functional role of Tsc22d3. METHODS: We identified the zebrafish Tsc22d3 and performed knockdown studies using morpholino antisense oligonucleotide (MO). RESULTS: Zebrafish Tsc22d3 did not response to hypertonic stress and ts22d3 knockdown or overexpression by injecting MO or capped RNA did not change the transcriptional levels of any of the known ionocyte markers. To reveal the unknown function of zebrafish Tsc22d3, we performed several in situ molecular marker studies on tsc22d3 morphants and found that Tsc22d3 plays multi-functional roles in dorsoventral (DV) patterning, segmentation, and brain development. We then aimed to identify the mechanism of Tsc22d3 in the earliest stages of DV patterning. Our results demonstrated that tsc22d3 is a ventralizing gene that can stimulate the transcription of bone morphogenetic protein 4 (bmp4) and, thus, has a positive effect on the Bmp signaling pathway. Furthermore, we showed that Tsc22d3 interacts with deubiquitylating enzymes, ubiquitin-specific protease 15 (Usp15) and ovarian tumor domain containing protein 4 (Otud4). In addition, the interruption of Bmp4 signaling by double knockdown of usp15 and otud4 reduced the ventralized effects in tsc22d3-overexpressing embryos. CONCLUSIONS: This is the first study to identify new developmental functions of Tsc22d3 in zebrafish. GENERAL SIGNIFICANCE: Zebrafish tsc22d3 is a ventralizing gene and plays a role in early embryogenesis.

Role of MIF/CXCL8/CXCR2 signaling in the growth of nasopharyngeal carcinoma tumor spheres.

Macrophage migration inhibitory factor (MIF) and CXCL8 (also named IL-8) are strongly expressed in the tissues of nasopharyngeal carcinoma (NPC). However, their role in the growth of NPC has not been fully examined. This study aims to evaluate the functions of MIF and CXCL8 on the growth of NPC tumor spheres. The elevated expression of CXCL8 in tumor over normal tissues was confirmed in 37 pairs of biopsies from NPC patients. In the in vitro study, all the poorly differentiated NPC cell lines, including the EBV-positive C666-1, and the EBV-negative CNE-1, CNE-2, SUNE-1, HNE-1 and HONE-1 cells, were found to express CXCL8 and MIF. Therefore, the EBV-positive C666-1 cell was selected to examine for the role of MIF and CXCL8 in the growth of the NPC tumor spheres. Functional study showed that the growth of C666-1 tumor spheres, under the nutrient poor or growth factor supplemented culture conditions, could be inhibited by the CXCL8 specific peptide inhibitor. The growth of the tumor spheres could also be reduced by the CXCR2 specific inhibitor SB225002 or the PI3K/AKT inhibitor LY294002, indicating that the endogenously produced CXCL8 plays an autocrine role in the growth of the tumor spheres. Further mechanistic studies revealed that the gene expression of CXCL8 could be reduced by the MIF specific small interfering RNA (siRNA) or NF-κB inhibitor parthenolide, and the growth of tumor spheres was also reduced after MIF siRNA transfection. Taken together, the present study highlights the role of MIF/CXCL8/CXCR2 axis in the growth of NPC tumor spheres. Chemotherapeutic interference of this signaling pathway may help to control the growth of the NPC tumor.

Concentrations of organochlorine pesticides (OCPs) in human blood plasma from Hong Kong: markers of exposure and sources from fish.

Previous studies revealed that food, particularly fish products, is the major source for human exposure to organochlorine pesticides (OCPs). Our previous studies revealed that contamination of Hong Kong market fish with DDT was 0.74-131 with a mean of 12.2 ng g(-1), ww, a result suggested that local people might be exposed to hazardous concentrations of OCPs. Therefore, the present systematic study was conducted to determine concentrations of OCPs in blood plasma of Hong Kong residents, develop marker substances and evaluate sources of 19 individual OCPs from fish. Concentrations of ∑OCPs, ∑DDTs and ∑HCHs ranged from 294 to 9732, 172 to 8842, and 115 to 1616 ng g(-1) lipid weight (lw), respectively. These concentrations were greater than those in blood of people from most developed countries but lower than those from most developing countries. The upper age group (>50 years) had significant (p<0.05) greater concentrations of OCPs than other groups. Furthermore, concentrations of OCPs in males were significantly (p<0.05) greater than those in females. p, p'-DDE was the predominant congener and marker substance of DDTs, while ß-HCH was the predominant congener and marker substance of HCHs. p, p'-DDE was more correlated with ∑OCPs (r(2)=0.830, p<0.05) than other individual OCPs, which suggested that p, p'-DDE is a good marker for accumulation of OCPs in blood plasma. Concentrations of individual OCPs were significantly correlated with not only their corresponding total concentrations in fishes from Hong Kong markets (r(2)=0.391, p=0.024), but also their bioaccessible fractions, which were estimated by an in vitro digestion method (r(2)=0.784, p=0.000). These results suggested that the in vitro gastrointestinal model is a more accurate method to evaluate accumulation of and health risks caused by dietary intake of OCPs. This study, which was the first systematic study to investigate concentrations of OCPs in blood of Hong Kong people, provides a baseline to which future measurements can be compared.

Arsenic contamination in the freshwater fish ponds of Pearl River Delta: bioaccumulation and health risk assessment.

This study investigated the extent of arsenic (As) contamination in five common species of freshwater fish (northern snakehead [Channa argus], mandrarin fish [Siniperca chuatsi], largemouth bass [Lepomis macrochirous], bighead carp [Aristichthys nobilis] and grass carp [Ctenopharyngodon idellus]) and their associated fish pond sediments collected from 18 freshwater fish ponds around the Pearl River Delta (PRD). The total As concentrations detected in fish muscle and sediment in freshwater ponds around the PRD were 0.05-3.01 mg kg(-1) wet weight (w. wt) and 8.41-22.76 mg kg(-1) dry weight (d. wt), respectively. In addition, the As content was positively correlated (p < 0.05) to total organic carbon (TOC) contents in sediments. Biota sediment accumulation factor (BSAF) showed that omnivorous fish and zooplankton accumulated higher concentrations of heavy metals from the sediment than carnivorous fish. In addition, feeding habits of fish also influence As accumulation in different fish species. In this study, two typical food chains of the aquaculture ponds were selected for investigation: (1) omnivorous food chain (zooplankton, grass carp and bighead carp) and (2) predatory food chain (zooplankton, mud carp and mandarin fish). Significant linear relationships were obtained between log As and δ (15)N. The slope of the regression (-0.066 and -0.078) of the log transformed As concentrations and δ (15)N values, as biomagnifications power, indicated there was no magnification or diminution of As from lower trophic levels (zooplankton) to fish in the aquaculture ponds. Consumption of largemouth bass, northern snakehead and bighead carp might impose health risks of Hong Kong residents consuming these fish to the local population, due to the fact that its cancer risk (CR) value exceeded the upper limit of the acceptable risk levels (10(-4)) stipulated by the USEPA.

Effect of benzo[a]pyrene on the production of vascular endothelial growth factor by human eosinophilic leukemia EoL-1 cells.

Benzo[a]pyrene (BaP) has been shown to affect both the development and response of T and B cells in the immune system. However, the effect of BaP on other immune cells, such as eosionophils, is unknown. In this study, we investigated the effect of BaP on the production of vascular endothelial growth factor (VEGF) using an in vitro eosinophilic EoL-1 cell and human umbilical vein endothelial cell (HUVEC) co-culture system. EoL-1-conditioned medium was found to promote the growth of HUVEC in a time-dependent manner. The growth stimulating activity was due to the production of VEGF by the EoL-1 cells. The production of VEGF was correlated with the enhanced expression of the phosphorylated form of extracellular signal-regulated kinases (p-ERKs) and the upregulated expression of VEGF mRNA. Furthermore, BaP-induced expression of VEGF mRNA was reduced by the ERK inhibitor PD98059. Results from this study suggested that BaP might affect the growth of endothelial cells through the modulation of VEGF production by eosinophils.

Daily intake and human risk assessment of organochlorine pesticides (OCPs) based on Cambodian market basket data.

To assess organochlorine pesticide (OCP) contaminations and its possible adverse health impacts, different food samples were collected from three areas of Cambodia, one of the poorest countries in the world. The ∑OCP concentrations in Kampong Cham, Kratie and Kandal provinces ranged from 1.28 to 188 (median 3.11), 1.06 to 25.1 (5.59) and 2.20 to 103 (20.6) ng g(-1), respectively. The dichlorodiphenyltrichloroethanes (DDTs) were the predominant OCPs and accounted for 62.2% (median) among all foodstuffs. Congener profile analyses suggested that there were new input sources of DDTs and hexachlorocyclohexanes (HCHs) in Cambodia, particularly in Kandal province. The estimated daily intake of OCPs (330 ng kg(-1)day(-1)) for residents in Kandal province ranked No. 1 among the 13 compared countries or regions. On the basis of 95th percentile concentrations, the carcinogenic hazard ratios (HRs) of most investigated individual OCPs in vegetable and fish in Cambodia exceeding unity. Particularly for α-HCH in vegetable, the 95th HR was as high as 186. The data revealed that there is a great cancer risk for the local residents with life time consumption of OCP contaminated vegetable and fish. To our knowledge, this the first study to evaluate the daily intakes of OCPs in Cambodia.