Nonylphenol enhances apoptosis induced by serum deprivation in PC12 cells

Head dysgenesis and disruption of cranial neural crest stem cells behaviour by 4-octylphenol in fire-bellied toad Bombina orientalis embryos

Alkylphenolic endocrine disruptors (Eds) have been known to affect development of the descendants of multipotent neural crest cells (NCCs) in amphibian embryos. To unravel the mechanism of head dysgenesis induced by alkylphenols in amphibians, the effect of 4-octylphenol (OP) on the differentiation of cranial NCCs in developing embryos and tadpoles, ex vivo NC explant, and isolated NCCs was examined in fire-bellied toad Bombina orientalis with 0, 1, 2, 5, 10, 25 and 50 μM concentrations. Following OP treatment, head cartilages were frequently absent together with the decreased col2a1 mRNA level in tadpoles. While the lipid hydroperoxide (LPO), endoplasmic reticulum stress (ERS), apoptosis, and DNA fragmentation were significantly increased in stage 22 neulurae and heads of stage 45 tadpoles. In stage 22 neulurae, OP decreased sox9 mRNA, the master transcription factor for chondrogenic differentiation and increased undifferentiated NCC markers. The ectopic NCCs were found in endoderm while mesodermal SOX10(+) cells were decreased. In cranial NCCs isolated from stage 22 embryos, OP treatment decreased cellular survival and increased apoptosis, epithelial-mesenchymal transition (EMT) and cell migration. In chondrogenic induced cranial NC explants, OP treatment decreased SOX9(+) chondrocytes and cartilage development. Together, OP potentiated oxidative damage, apoptosis, EMT, and ectopic migration of NCCs. Considering that tissue differentiation requires stem cells to activate the molecular mechanism of differentiation at the correct location during embryonic development, these changes caused by OP may inhibit sox9-dependent chondrogenic differentiation of cranial NCCs, leading to head dysgenesis in B. orientalis embryos. Therefore, developing multipotent NCCs could be an important target of OP, provides new direction for the estimation of the risk of EDs exposure in human and wildlife animals.

4-Octylphenol induces developmental abnormalities and interferes the differentiation of neural crest cells in Xenopus laevis embryos

Developmental toxicity of 4-octylphenol (OP), an estrogenic endocrine disruptor was verified using frog embryo teratogenesis assay Xenopus. LC₅₀, EC_{50Malformtion} and EC_{50Melanocyte-dysgenesis} of OP were 9.9, 10.5, and 2.4 μM, respectively. In tadpoles, despite the low teratogenic index, 2 μM OP significantly inhibited head cartilage development and tail malformation. The total length of tadpole was significantly increased at 5 μM and decreased at 10 μM OP. In OP-treated tadpoles, head cartilages were frequently missed and col2a1 mRNA was decreased at 2 μM, indicating a chondrogenic defect in developing head. In the head skin of 1 μM OP-treated tadpoles, number of melanocytes and melanogenic pathway genes expression were significantly decreased. In the head-neck junction of stage 22 embryos, OP increased foxd3 and sox10 mRNA and SOX10(+) neural crest cells (NCCs) in somite mesoderm and endoderm, indicating the inhibition of chondrogenic differentiation, ectopic migration to endoderm, and undifferentiation of NCCs by OP. Together, OP-induced head dysplasia and inhibition of melanogenesis may be attributable to deregulation of neural crest cells in embryos. In tadpoles, OP at 1 μM significantly increased lipid hydroperoxide and induced spliced xbp1 mRNA, an IRE1 pathway endoplasmic reticulum stress (ERS) marker and p-eIF2α protein, a PERK pathway ERS marker. OP at 10 μM induced CHOP mRNA, pro-apoptotic genes expression, DNA fragmentation, and cleaved caspase-3, suggesting that OP differentially induced ERS and apoptosis according to the concentration in embryos. In 5-10 μM OP-treated stage 22 embryos and stage 45 tadpole heads, Ki67 was significantly increased, suggesting the apoptosis-induced proliferation of embryonic cells in the OP-treated embryos. Together, OP should be managed as a developmental toxicant altering the behavior of NCCs in vertebrates.

Oxidative Stress and Apoptosis Contributed to Nonylphenol-Induced Cell Damage in Mouse NCTC Clone 1469 Cells

Nonylphenol (NP) is considered an environmental toxicant and endocrine-disrupting compound. The present study aimed to investigate the effects of NP on NCTC Clone 1469, nonparenchymal hepatocytes, and to study the molecular basis of NP-induced liver injury. The results showed that NP decreased cell viability and induced nucleus crenulation and intracellular enzyme leakage in NCTC Clone 1469 cells. Additionally, NP-induced oxidative stress and apoptosis of NCTC Clone 1469 are accompanied by upregulating reactive oxygen species (ROS) production, increase of Bax, decrease of Bcl-2, activation of caspase-3 and caspase-12, and release of cytosolic free Ca2+ in the cells. ROS scavenger, N-acetyl-L-cysteine (NAC), prevented the intracellular enzyme leakage induced by NP. NP induced alteration of estrogen receptor- (ER-) α and ER-β expression, while ER antagonists, ICI 182,780, showed no effect on NP-induced intracellular enzyme leakage. We proposed that NP triggered cell damage via inducing oxidative stress and apoptosis in cells, but not estrogenic effect.

Oxidative stress in liver cell culture from mullet, Liza klunzingeri, induced by short-term exposure to benzo[a]pyrene and nonylphenol

The present investigation aimed to use primary liver cell culture obtained from mullet, Liza klunzingeri, to evaluate the toxic effects of benzo[a]pyrene (BaP) and nonylphenol (NP) on the antioxidant defense system. Liver samples taken from 20 L. klunzingeri were digested with 0.1% collagenase IV. The digested cells were then moved to Leibovitz L-15 culture medium and incubated at 25 °C for 2 weeks. 10^-5 mol/l of BaP and 10^-4 mol/l of NP were considered as the half maximal inhibitory concentration (IC50). Cells were then incubated with L-15 medium containing BaP (0[control], 10^-6,2 × 10^-6,3 × 10^-6 mol/l) and NP (0[control],10^-5,2 × 10^-5,3 × 10^-5 mol/l), and sampling was performed after 6, 12, and 24 h of incubation for measurement of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), lipid peroxidation (LPO), total antioxidant power, and total protein. The lowest concentration of BaP and NP did not have considerable toxic effects on cultivated hepatocytes. The activities of SOD, CAT, GPx, LPO, total antioxidant power, and total protein changed dose-dependently in cells treated with BaP and NP. In conclusion, based on the results, short-term exposure to BaP and NP induced the oxidative stress in cultivated liver cells of L. klunzingeri. The toxicity of both pollutants is mainly because of the induction of the reactive oxygen species (ROS), which lead to cell membrane disruption, damage of cellular metabolism, and interference with cellular macromolecules.

Potential Health Risks Linked to Emerging Contaminants in Major Rivers and Treated Waters

The presence of endocrine-disrupting chemicals (EDCs) in our local waterways is becoming an increasing threat to the surrounding population. These compounds and their degradation products (found in pesticides, herbicides, and plastic waste) are known to interfere with a range of biological functions from reproduction to differentiation. To better understand these effects, we used an in silico ontological pathway analysis to identify the genes affected by the most commonly detected EDCs in large river water supplies, which we grouped together based on four common functions: Organismal injuries, cell death, cancer, and behavior. In addition to EDCs, we included the opioid buprenorphine in our study, as this similar ecological threat has become increasingly detected in river water supplies. Through the identification of the pleiotropic biological effects associated with both the acute and chronic exposure to EDCs and opioids in local water supplies, our results highlight a serious health threat worthy of additional investigations with a potential emphasis on the effects linked to increased DNA damage.

Endocrine-disrupting metabolites of alkylphenol ethoxylates - A critical review of analytical methods, environmental occurrences, toxicity, and regulation

Despite the fact that metabolites of alkylphenol ethoxylates (APEO) are classified as hazardous substances, they continue to be released into the environment from a variety of sources and are not usually monitored. Their wide use has led to an increase in the possible exposure pathways for humans, which is cause for alarm. Moreover, there is a lack of knowledge about the behaviour of these metabolites with respect to the environment and toxicity, and their biological effects on human health. The aim of this work is to give an overview of the APEO metabolites and their analysis, occurrences and toxicity in various environmental and human samples. APEO metabolites have adverse effects on humans, wildlife, and the environment through their release into the environment. Currently, there are some reviews available on the behaviour of alkylphenols in soil, sediments, groundwater, surface water and food. However, none of these articles consider their toxicity in humans and especially their effect on the nervous and immune system. This work summarises the environmental occurrences of metabolites of APEOs in matrices, e.g. water, food and biological matrices, their effect on the immune and nervous systems, and isomer-specific issues. With that emphasis we are able to cover most common occurrences of human exposure, whether direct or indirect.

The possible DNA damage induced by environmental organic compounds: The case of Nonylphenol

Human impact on the environment leads to the release of many pollutants that produce artificial compounds, which can have harmful effects on the body's endocrine system; these are known as endocrine disruptors (EDs). Nonylphenol (NP) is a chemical compound with a nonyl group that is attached to a phenol ring. NP-induced H₂AX is a sensitive genotoxic biomarker for detecting possible DNA damage; it also causes male infertility and carcinogenesis. We attempt to comprehensively review all the available evidence about the different ways with descriptive mechanisms for explaining the possible DNA damage that is induced by NP. We systematically searched several databases, including PubMed, Scopus, Web of Science, and gray literature, such as Google Scholar by using medical subheading (MeSH) terms and various combinations of selected keywords from January 1970 to August 2017. The initial search identified 62,737 potentially eligible studies; of these studies, 33 were included according to the established inclusion criteria. Thirty-three selected studies, include the topics of animal model (n = 21), cell line (n = 6), human model (n = 4), microorganisms (n = 1), solid DNA (n = 1), infertility (n = 4), apoptosis (n = 6), and carcinogenesis (n = 3). This review highlighted the possible deleterious effects of NP on DNA damage through the ability to produce ROS/RNS. Finally, it is significant to observe caution at this stage with the continued use of environmental pollutants such as NP, which may induce DNA damage and apoptosis.

Using a liver cell culture from Epinephelus coioides as a model to evaluate the nonylphenol-induced oxidative stress

The present study aimed to use primary liver cell culture derived from the orange-spotted grouper, Epinephelus coioides, to assess the toxic effects of nonylphenol (NP) on the hepatocyte viability and the liver antioxidant system. E. coioides was selected due to its commercial importance. NP was used in this study because of its high potential of producing oxidative stress due to increased reactive oxygen species (ROS). A liver of E. coioides was digested with PBS containing 0.1% collagenase IV. The digested cells were moved to Leibovitz L-15 culture medium with 20% fetal bovine serum (FBS), 100IUmL^-1 penicillin, 100μgmL^-1 streptomycin. Aliquots of cell suspension were seeded as a monolayer into sterile 25cm² tissue culture flasks and incubated at 30°C for 14days. The medium, containing non-attached cells, was removed after 24 to 48h and a new medium was added. The IC50 of 10^-4molL^-1 was determined for nonylphenol using MTT assay. Cells were then incubated with L-15 medium containing 10^-5, 2×10^-5, 3×10^-5molL^-1 of NP and samples were taken after 6, 12 and 24h of incubation for analysis of LPO, SOD, CAT, GPx, LDH, AST, ALT, and ALP. Based on the results, the lowest concentration of NP was not markedly cytotoxic to primary hepatocytes and the cell sensitivity to NP increased dose-dependently. The activities of SOD, CAT and GPx decreased significantly, while activities of LPO, LDH, AST, ALT and ALP, increased significantly in a dose-related pattern in NP-treated cells. In conclusion, this study revealed that NP could induce the oxidative stress in cultivated hepatocytes of E. coioides during a short-term exposure. NP toxicity is mainly due to the induction of the reactive oxygen species (ROS), which lead to cell membrane disruption, damage of cellular metabolism, and interference with cellular macromolecules.

Nonylphenol increases tumor formation and growth by suppressing gender-independent lymphocyte proliferation and macrophage activation

Nonylphenol (NP) is a well-known endocrine disruptor that influences sexual and reproductive development. Here, we investigated whether NP affects immune responses that are associated with tumor initiation and progression. When spleen cells were incubated with lipopolysaccharide (LPS) and concanavalin A in the presence of 10^-4 M NP, the proliferation of B and T lymphocytes was reduced compared with that in controls, in a gender-independent fashion. While 10^-4 M NP also decreased the production of nitric oxide (NO) in LPS-stimulated bone marrow-derived macrophages (BMDMs), no changes in NO production were detected following treatment with 10^-5 M NP. LPS-stimulated expression of iNOS, COX2, IL-6 and TNF-α in BMDMs was reduced after 6 or 18 hours of incubation with 10^-5 M NP. Furthermore, when mice were pre-exposed to NP for 7 days prior to the injection of B16F10 melanoma cells, the rates of tumor nodule formation and relative tumor growth were higher than those in the control group. In vivo immunosuppressive effect was also clarified by the inhibition of proliferation in B/T lymphocyte and cytokine production in peritoneal macrophages from the mice pretreated with NP for 7 days. Taken together, these data demonstrate that NP could affect the immune responses of lymphocytes and macrophages, leading to the suppression of their tumor-preventing ability. This suggests that individuals at high risk for tumor development should avoid frequent exposure to NP and other endocrine disruptors.

Polarized macrophages treated with nonylphenol differently regulate lipopolysaccharide-induced sepsis

Nonylphenol (NP) as well-known "endocrine disrupter" influences sexual and reproductive development. Here, we investigated the effect of NP on M1-/M2-type macrophages and their role in lipopolysaccharide (LPS)-induced sepsis. Polarized macrophages of M1- and M2-types were obtained by the treatment with LPS and interleukin-4 (IL-4) to bone marrow-derived macrophages (BMDM), respectively. Coincubation of M1-macrophages with NP decreased COX-2, iNOS, IL-6, and TNF-α expression but no changes were detected in the production of nitric oxide (NO). Survival probability of LPS-induced sepsis mice was enhanced by the injection of NP-treated BMDM as compared to the injection of NP-untreated control BMDM. In the meanwhile, the expression of arginase 1(Arg1), a marker for M2-polarized macrophages was increased by the stimulation with LPS in BMDM. Arg1 expression was also enhanced by the treatment with IL-4 in BMDM, which was reduced by the coincubation with NP. Survival probability of LPS-induced sepsis mice was decreased by the injection of BMDM treated with IL-4 and NP as compared to the injection of IL-4-treated BMDM. It suggests that NP might inhibit macrophage function and the polarization to M2-macrophages. Taken together, data demonstrate that NP could differently affect immune responses of polarized macrophages resulted in the modulation of LPS-induced sepsis. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 2081-2089, 2016.

Nonylphenol diethoxylate inhibits apoptosis induced in PC12 cells

Nonylphenol and short-chain nonylphenol ethoxylates such as NP₂ EO are present in aquatic environment as wastewater contaminants, and their toxic effects on aquatic species have been reported. Apoptosis has been shown to be induced by serum deprivation or copper treatment. To understand the toxicity of nonylphenol diethoxylate, we investigated the effects of NP₂ EO on apoptosis induced by serum deprivation and copper by using PC12 cell system. Nonylphenol diethoxylate itself showed no toxicity and recovered cell viability from apoptosis. In addition, nonylphenol diethoxylate decreased DNA fragmentation caused by apoptosis in PC12 cells. This phenomenon was confirmed after treating apoptotic PC12 cells with nonylphenol diethoxylate, whereas the cytochrome c release into the cytosol decreased as compared to that in apoptotic cells not treated with nonylphenol diethoxylates. Furthermore, Bax contents in apoptotic cells were reduced after exposure to nonylphenol diethoxylate. Thus, nonylphenol diethoxylate has the opposite effect on apoptosis in PC12 cells compared to nonylphenol, which enhances apoptosis induced by serum deprivation. The difference in structure of the two compounds is hypothesized to be responsible for this phenomenon. These results indicated that nonylphenol diethoxylate has capability to affect cell differentiation and development and has potentially harmful effect on organisms because of its unexpected impact on apoptosis. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1389-1398, 2016.

RXRα, PXR and CAR xenobiotic receptors mediate the apoptotic and neurotoxic actions of nonylphenol in mouse hippocampal cells

In the present study, we investigated the role of the retinoid X receptor (RXR), the pregnane X receptor (PXR) and the constitutive androstane receptor (CAR), in the apoptotic and toxic effects of nonylphenol in mouse primary neuronal cell cultures. Our study demonstrated that nonylphenol activated caspase-3 and induced lactate dehydrogenase (LDH) release in hippocampal cells, which was accompanied by an increase in the mRNA expression and protein levels of RXRα, PXR and CAR. Nonylphenol stimulated Rxra, Pxr, and Car mRNA expression. These effects were followed by increase in the protein levels of particular receptors. Immunofluorescence labeling revealed the cellular distribution of RXRα, PXR and CAR in hippocampal neurons in response to nonylphenol, shortening of neurites and cytoplasmic shrinking, as indicated by MAP2 staining. It also showed NP-induced translocation of receptor-specific immunofluorescence from cytoplasm to the nucleus. The use of specific siRNAs demonstrated that Rxra-, Pxr-, and Car-siRNA-transfected cells were less vulnerable to nonylphenol-induced activation of caspase-3 and LDH, thus confirming the key involvement of RXRα/PXR/CAR signaling pathways in the apoptotic and neurotoxic actions of nonylphenol. These new data give prospects for the targeting xenobiotic nuclear receptors to protect the developing nervous system against endocrine disrupting chemicals.

Environmental immune disruptors, inflammation and cancer risk

An emerging area in environmental toxicology is the role that chemicals and chemical mixtures have on the cells of the human immune system. This is an important area of research that has been most widely pursued in relation to autoimmune diseases and allergy/asthma as opposed to cancer causation. This is despite the well-recognized role that innate and adaptive immunity play as essential factors in tumorigenesis. Here, we review the role that the innate immune cells of inflammatory responses play in tumorigenesis. Focus is placed on the molecules and pathways that have been mechanistically linked with tumor-associated inflammation. Within the context of chemically induced disturbances in immune function as co-factors in carcinogenesis, the evidence linking environmental toxicant exposures with perturbation in the balance between pro- and anti-inflammatory responses is reviewed. Reported effects of bisphenol A, atrazine, phthalates and other common toxicants on molecular and cellular targets involved in tumor-associated inflammation (e.g. cyclooxygenase/prostaglandin E2, nuclear factor kappa B, nitric oxide synthesis, cytokines and chemokines) are presented as example chemically mediated target molecule perturbations relevant to cancer. Commentary on areas of additional research including the need for innovation and integration of systems biology approaches to the study of environmental exposures and cancer causation are presented.

Mitogen-activated protein kinase and Akt pathways are involved in 4-n-nonyphenol induced apoptosis in mouse Sertoli TM4 cells

Nonylphenol (NP) is considered an important environmental toxicant, which may disrupt male reproductive system. The aim of this study was to investigate 4-n-nonylphenol (4-n-NP) induced apoptosis and its related mechanism in mouse Sertoli cell line, TM4 cells. Our results showed that NP treatment (0.1, 1, 10, 20 and 30 μM) decreased cell viability and induced apoptosis in the cells, accompanied by alteration of Bcl-2 family mRNA expression, activation of caspases-3, release of Ca(2+), and increase of reactive oxygen species (ROS) generation. Subsequently, it was found that the levels of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-PX) in the cells were markedly decreased, and maleic dialdehyde (MDA) content was increased by NP treatment. Then activation of the mitogen-activated protein kinases (MAPKs) pathways and inhibition of Akt pathway were simultaneously detected in NP challenged TM4 cells. Taken together, it was concluded that NP induced cytotoxicity and apoptosis in TM4 cells, and the apoptosis may be mediated via MAPKs and Akt pathways in addition to Ca(2+) release and ROS generation.

Benzophenone-1 and nonylphenol stimulated MCF-7 breast cancer growth by regulating cell cycle and metastasis-related genes via an estrogen receptor α-dependent pathway

Endocrine-disrupting chemicals (EDC) are defined as environmental compounds that produce adverse health manifestations in mammals by disrupting the endocrine system. Benzophenone-1 (2,4-dihydroxybenzophenone, BP1) and nonylphenol (NP), which are discharged from numerous industrial products, are known EDC. The aim of this study was to examine the effects of BP1 and NP on proliferation and metastasis of MCF-7 human breast cancer cells expressing estrogen receptors (ER). Treatment with BP1 (10⁻⁵-10⁻⁷ M) and NP (10⁻⁶-10⁻⁷ M) promoted proliferation of MCF-7 cells similar to the positive control 17 -beta-estradiol (E2). When ICI 182,780, an ER antagonist, was co-incubated with E2, BP1, or NP, proliferation of MCF-7 cells returned to the level of a control. Addition of BP1 or NP markedly induced migration of MCF-7 cells similar to E2. To elucidate the underlying molecular mechanisms produced by these EDC, alterations in transcriptional and translational levels of proliferation and metastasis-related markers, including cyclin D1, p21, and cathepsin D, were determined. Data showed increase in expression of cyclin D1 and cathepsin D and decrease in p21 at both transcriptional and translational levels. However, BP1- or NP-induced alterations of these genes were blocked by ICI 182,780, suggesting that changes in expression of these genes may be regulated by an ERα-dependent pathway. In conclusion, BP1 and NP may accelerate growth of MCF-7 breast cancer cells by regulating cell cycle-related genes and promote cancer metastasis through amplification of cathepsin D.

Ameliorating effect of chicory (Chichorium intybus L.) fruit extract against 4-tert-octylphenol induced liver injury and oxidative stress in male rats

The current study was carried out to elucidate the modulating effect of chicory (Cichorium intybus L.) fruit extract (CFR) against 4-tert-OP induced oxidative stress and hepatotoxicity in male rats. Rats were divided into four groups and treated for 8 weeks as follow: group 1: normal control-treated (saline); group 2: chicory fruit extract-treated (100 mg/kg); group 3: 4-tert-OP treated; group 4: 4-tert-OP plus chicory fruit extract. The obtained results revealed that rats which received 4-tert-OP showed a significant increase in liver TBARS and bilirubin, aspartate aminotransferase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and gamma-glutamyl transpeptidase (GGTP) activities. While a significant decrease in the levels of GSH, SOD, catalase recorded. On the other hand, CFR extract succeeded to modulate these observed abnormalities resulting from 4-tert-OP as indicated by the reduction of TBARS and the pronounced improvement of the investigated biochemical and antioxidant parameters. Histopathological evidence, together with observed PCNA and DNA fragmentation, supported the detrimental effect of 4-tert-OP and the ameliorating effect of CFR extract on liver toxicity. So, it could be concluded that chicory has a promising role and it worth to be considered as a natural substance for ameliorating the oxidative stress and hepatic injury induced by 4-tert-OP compound.

Aspartame-induced apoptosis in PC12 cells

Aspartame is an artificial sweetner added to many low-calorie foods. The safety of aspartame remains controversial even though there are many studies on its risks. In this study, to understand the physiological effects of trace amounts of artificial sweetners on cells, the effects of aspartame on apoptosis were investigated using a PC12 cell system. In addition, the mechanism of apoptosis induced by aspartame in PC12 cells and effects on apoptotic factors such as cytochrome c, apoptosis-inducing factor, and caspase family proteins were studied by Western blotting and RT-PCR. Aspartame-induced apoptosis in PC12 cells in a dose-dependent manner. In addition, aspartame exposure increased the expressions of caspases 8 and 9, and cytochrome c. These results indicate that aspartame induces apoptosis mainly via mitochondrial pathway involved in apoptosis due to oxigen toxicity.

Effects of UV wavelength on cell damages caused by UV irradiation in PC12 cells

Ultraviolet (UV) radiations present in sunlight are a major etiologic factor for many skin diseases and induce DNA damage through formation of cyclobutane pyrimidine dimer (CPD). This study was conducted to determine the toxicological effects of different wavelengths (250, 270, 290, and 310 nm) and doses of UV radiation on cell viability, DNA structure, and DNA damage repair mechanisms in a PC12 cell system. For this, we evaluated cell viability and CPD formation. Cell survival rate was markedly decreased 24h after UV irradiation in a dose-dependent manner at all wavelengths (except at 310 nm). Cell viability increased with increasing wavelength in the following order: 250<270<290<310 nm. UV radiation at 250 nm showed the highest cell killing ability, with a median lethal dose (LD50) of 120 mJ/cm(2). The LD50 gradually increased with increase in wavelength. Among the 4 wavelengths tested, the highest LD50 (6000 mJ/cm(2)) was obtained for 310 nm. CPD formation decreased substantially with increasing wavelength. Among the 4 wavelengths, the proportion of CPD formation was highest at 250 nm and lowest at 310 nm. On the basis of LD50 values for each wavelength, PC12 cells irradiated with UV radiation of 290 nm showed maximum DNA repair ability, whereas those irradiated with the 310-nm radiation did not show any repair ability. Toxicity of UV radiation varied with wavelengths and exposure doses.

Diethyl phthalate enhances apoptosis induced by serum deprivation in PC12 cells

In this study, to examine the mechanism of diethyl phthalate toxicity to cells, the effects of diethyl phthalate on apoptosis in a PC12 cell system were investigated by assaying apoptotic factors such as caspase-3, Bax, cytochrome c and DNA damage. Diethyl phthalate was shown to enhance the apoptosis induced by serum deprivation according to the results of DNA electrophoresis and TUNEL signal assays, although it could not induce apoptosis itself in the cells. This enhancement was thought to be because of an increase in caspase-3-like activity. In addition, the expression of bax and contents of cytochrome c in the cytosol showed a tendency to increase the cells exposed to diethyl phthalate. These results indicated that diethyl phthalate, a potential endocrine disrupter, affects the apoptotic system in PC12 cells. Diethyl phthalate may enhance oxidative stress such as that induced by reactive oxygen species in PC12 cells.

Effects of parabens on apoptosis induced by serum-free medium

Alkyl esters of p-hydroxybenzoic acids (parabens), an endocrine disrupter, are used as preservatives in cosmetics and foods. In this study, to understand the relationship between parabens and differentiation in infants, the effects of parabens on apoptosis induced by serum deprivation in PC12 cells were investigated. In addition, apoptosis-related factors were assayed. As results, a tendency toward enhancement of apoptosis was observed in the cells cultured in the serum-free medium with methylparaben, and this tendency was suggested to be related to the contents of BAD, a pro-apoptotic protein. Butylparaben did not show any tendency to enhance apoptosis.

Effects of 17α-ethynylestradiol and nonylphenol on liver and gonadal apoptosis and histopathology in Chalcalburnus tarichi

Chalcalburnus tarichi is an endemic cyprinid fish living in the Lake Van basin located in the Eastern Turkey. Fish (3+ ages) were exposed to 17α-ethynylestradiol (EE(2); 1, 10, 100 ng L(-1); nominal concentrations) and nonylphenol (NP; 10, 60, 200 μg L(-1) ; nominal concentrations) for 32 days under semistatic daily renewal conditions. The exposure period was followed by an evaluation of liver and gonadal apoptosis and gonad histopathology in males and females. Exposure to the highest concentrations of EE(2) (100 ng L(-1)) and NP (200 μg L(-1) ) caused significant increases in the extent of apoptosis in liver and gonads. Treatment with 100 ng L(-1) of EE(2) and 200 μg L(-1) NP increased the number of TUNEL positive hepatocytes significantly in both sexes compared to controls. The rates of apoptosis in testicular germ cells and ovarian follicular cells were significantly greater at the same concentrations. Exposure to EE(2) (100 ng L(-1)) and NP (60 and 200 μg L(-1)) caused thickening of interstitial connective tissue (fibrosis) in the seminiferous tubule wall and testis-ova formation in males. In females treated with 100 ng L(-1) EE(2) , increased percentage of atretic ooctytes and fibrotic areas in the ovarian somatic stromal tissue were found in the ovaries. Increase in atresia, without a statistical significance, and fibrotic stromal tissue were also noted in 60 and 200 μg L(-1) NP treatments. Results suggest that EE(2) - and NP-dependent hepatotoxicity and gonadotoxicity are causally related to the increase in apoptosis in C. tarichi.

A flounder (Paralichthys olivaceus) gill cell line as in vitro acute assay system of nonylphenol cytotoxicity

A cell line (FG cells) derived from a gill of the flounder, Paralichthys olivaceus were used to determine the cytotoxic effects of nonylphenol (NP). Cytotoxicity was measured by three endpoint systems: neutral red (NR) uptake assay, methyl thiazolyl tetrazolium (MTT) assay and cell protein assay. The result showed that NP was cytotoxic to FG cells at all tested concentrations, and toxicity increased as the concentration of NP was progressively increased. The 24 h-IC50 values of NP were 39.81, 37.76 and 38.22 μmol/L for NR uptake, MTT assay and cell protein assay, respectively. Moreover, the morphological changes of FG cells were also studied at the concentration of 30 μmol/L for 24 h. Cells morphology were markedly altered by NP observed under a scanning electron microscopy, as evidenced by swelling cells, two and more nucleolus and an increased number of lipid particles. This would suggest that the FG cell line is a suitable bioindicator for the screening of the acute toxicity of NP.

Comparison of general water quality of rivers in Indonesia and Japan

In Java and Kalimantan in Indonesia, river water plays important roles in human life; for example, for transportation, and economic activities of the inhabitants. However, industrial, agricultural and domestic water is discarded into rivers directly in many developing countries, including Indonesia, since drainage systems have not been completely constructed. In this study, to evaluate the water quality and to compare those levels of environmental contaminants in developing and developed countries, water quality and contents of endocrine disrupters were measured in a total of 64 water samples (Indonesia; 28 samples and Japan; 36 samples) from 53 sites. The results indicated that, rivers in both capital cities, Jakarta and Tokyo, were contaminated. Water in rivers in Indonesia was not so heavily polluted as in Japan. Pollution in the river water in Indonesia appeared to be caused by the lack of sewerage systems. In addition, the findings on endocrine disrupters indicated that the concentration of alkylphenol in water samples was large enough to affect living organisms.

Effects of gamma-hexachlorocyclohexane on apoptosis induced by serum deprivation in PC12 cells

The effects of gamma-hexachlorocyclohexane, one of the endocrine disrupters, widely used for agricultural and medicinal purpose, on apoptosis in PC12 cells were investigated using western blotting analysis and reverse transcriptase-DNA polymerase chain reaction (RT-PCR) method. Apoptosis is a fundamental process necessary for development of individuals and organs. Although gamma -HCH at high concentration did not have an effect on cell viability and apoptosis, DNA fragmentation was slightly enhanced, and apoptotic factors; Bax, Bad, cytochrome c and caspase-3 showed tendency to increase by the addition of a low dose of gamma-HCH to the cell medium. However these changes were not statistically significant. It was concluded that gamma -HCH did not affect on apoptosis in the PC12 cell line system, although gamma -HCH has been reported to induce apoptosis in other cell lines.

Chronic application of nonylphenol-induced apoptosis via suppression of bcl-2 transcription and up-regulation of active caspase-3 in mouse brain

Nonylphenol (NP) is an endocrine disruptor, which has been reported to have adverse effects on reproductive and immune systems. However, the influence of NP on the central nervous system (CNS) has not been extensively explored. The present study was performed to investigate the effects of chronic administration of NP on the apoptosis-related protein expression in mouse brain by in situ hybridization, RT-PCR and immunoblotting assays. The expression of bcl-2 mRNA was down-regulated by NP at the doses of 100 and 200mg/(kg day) (p<0.05), whereas the expression of bax mRNA was not affected in NP treated mice (p>0.05). Furthermore, as the main executor of apoptosis, the expression of active caspase-3 was up-regulated by 100 and 200mg/(kg day) NP (p<0.01), which is in accord with the results of terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL) (p<0.05). These results suggest that chronic application of NP could sensitize the mice brain to apoptosis.

Nonylphenol induces apoptosis of Jurkat cells by a caspase-8 dependent mechanism

Nonylphenol is the final biodegradation product of nonylphenol polyethoxylates, which are widely used surfactants in domestic and industrial products. Although nonylphenol is well known as an endocrine disrupting chemical, its effects on cell death and the mechanisms responsible for these apoptotic effects remain unclear. In the present study, Jurkat cells were treated with 0.1, 1 and 10 microM nonylphenol for 12 and 24 h, respectively. Cell viability was assessed with a Cell Counting Kit. The effects of nonylphenol on apoptosis of Jurkat cells were determined by DNA fragmentation (DNA ladder), Hoechst33258, PI and Annexin V FITC/PI double staining. Changes in mitochondrial membrane potential were detected with JC-1 fluorescence. In addition, enzyme activity of caspase-8 was evaluated by flow cytometry. The results demonstrated that nonylphenol inhibited the proliferation and induced loss of mitochondrial membrane potential, caspase-8 activation, internucleosomal DNA fragmentation. Furthermore, a caspase-8 inhibitor, IETD-fmk, blocked loss of mitochondrial membrane potential and apoptosis. These findings suggested that nonylphenol induced apoptosis of Jurkat cells by caspase-8 dependent mechanisms.

Multigenerational study of the hepatic effects exerted by the consumption of nonylphenol- and 4-octylphenol-contaminated drinking water in Sprague-Dawley rats

Our multigenerational study evaluates the hepatic effects of the xenoestrogens nonylphenol (NP), and 4-octylphenol (4OP) on male and female rats when they are exposed uninterruptedly, from conception to adult age, to tap water containing 25ppm of NP or 4OP. Our results showed that these compounds did not induce any change in liver/body weight ratio (relative liver weight, RLW). In the morphological analysis we did not find evident signs of cytotoxicity. The most relevant findings were the presence of both an increase in the apoptotic index and in the percentage of binuclear hepatocytes in livers from exposed animals. Additionally, our study revealed the presence of hepatocellular glycogenosis (mainly in 4OP-exposed rats): the type of glycogen accumulated was in aggregates (gamma-glycogen), a non-functional form of glycogen. This study demonstrates that, at levels close to those described in the environment, NP and 4OP are capable of inducing a number of hepatic effects, potentially related with adaptive, and/or metabolic alterations of liver tissue.

Protective Effect of Lignophenol Derivative from Beech (Fagus crenata Blume) on Copper- and Zinc-Mediated Cell Death in PC12 Cells

Lignophenol, prepared using a phase-separation system, is a derivative of lignin, which is one of the components in the plant cell wall, and possesses high phenolic function, high stability and antioxidant properties. However, little is known about the beneficial effect of lignophenol. In this study, we investigated the protective effect of lignophenol from the beech tree (Fagus crenata Blume) on copper- and zinc-mediated apoptosis in PC12 cells by using DNA fragmentation and TUNEL assays. In DNA fragmentation assays, the DNA ladder patterns in the PC12 cells treated with 200 microM Cu and 200 microM Zn were enhanced, whereas the DNA ladder pattern was hardly observed in these cells treated with 20 mM lignophenol. In the TUNEL assay, TUNEL signals increased significantly in the untreated PC12 cells exposed to 200 microM Cu compared with the control. In contrast, the degree of apoptosis in the 20 mM lignophenol-treated cells was significantly lower than in the untreated cells, indicating that lignophenol inhibited Cu-induced apoptotic cell death in PC 12 cells. In the 200 microM Zn-exposed group, the degree of apoptosis in the 20 mM lignophenol-treated cells was also low compared with the untreated cells. In conclusion, these results suggest that lignophenol plays a role in protecting against Cu- and Zn-mediated PC12 apoptotic cell death.

Nonylphenol-induced oxidative stress and cytotoxicity in testicular Sertoli cells

Nonylphenol (NP) as an environment contaminant has been demonstrated to adversely affect male reproduction. The main objective of this study was to evaluate NP-induced oxidative stress and toxicity in testicular Sertoli cells. Sertoli cells were exposed to 10-40 microM NP for 24 h. Cell death and growth inhibition were observed by flow cytometric analysis and 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide (MTT) assay, while fluorescein diacetate (FDA) and propidium iodide (PI) staining was used to examine the morphological changes following NP exposure. Subsequently, we found that short-term treatment (2 h) of NP caused intracellular accumulation of reactive oxygen species (ROS), which was evaluated by loading of 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) without visible morphological changes. Loss of mitochondrial membrane potential (MMP) was detected following 12 and 24 h treatment of NP and assessment by Rhodamine 123 (Rh123) staining. In addition, incubation with NP for 12 h also increased lipid peroxidation of Sertoli cells. These results indicated that low micromolar concentrations of NP induce an adverse oxidative stress in rat Sertoli cells.

Nonylphenol-induced thymocyte apoptosis involved caspase-3 activation and mitochondrial depolarization

Although the effect of 4-nonylphenol on cells of immune system have long been recognized, little is known about the effect of 4-nonylphenol on the induction of apoptosis and related signaling events in the lymphoid cells. In the present study, we used cultured thymocytes of mice to investigate the ability of 4-nonylphenol to induce the apoptosis of thymocytes and to explore the role of signal transduction pathway leading to apoptosis. The results showed that the cytotoxic effects of 4-nonyphenol involved DNA fragmentation (DNA ladder), characteristic of apoptosis. Staining of 4-nonyphenol-treated thymocytes with DNA-binding fluorochrome Hoechst 33258 showed the typical apoptotic nuclei condensation and fragmentation of chromatin. The rates of apoptosis of the 4-nonylphenol-treated thymocytes increased significantly at 4 and 6 h, which were determined by analysis of hypodiploid cells and FITC-Annexin V and PI double staining. Flow cytometer analysis also revealed that the loss of mitochondrial membrane potential and increased activity of caspase-3 occurred concomitantly with the onset of 4-nonyphenol-induced apoptosis. Furthermore, a caspase-3 inhibitor, z-DEVD-fmk protected thymocytes from apoptosis induced by 4-nonyphenol. These results suggest that 4-nonylphenol induces thymocyte apoptosis via caspase-3 activation and mitochondrial depolarization.

Nonylphenol-induced Ca2+ elevation and Ca2+-independent cell death in human osteosarcoma cells

The effect of the environmental toxicant nonylphenol on cytosolic free Ca2+ concentration ([Ca2+]i) and proliferation has not been explored in human osteoblast-like cells. This study examined whether nonylphenol alters Ca2+ levels and causes cell death in MG63 human osteosarcoma cells. [Ca2+]i and cell death were measured using the fluorescent dyes fura-2 and WST-1 respectively. Nonylphenol at concentrations above 3 microM increased [Ca2+]i in a concentration-dependent manner. The Ca2+ signal was reduced by 90% by removing extracellular Ca2+. The nonylphenol-induced Ca2+ influx was insensitive to blockade of L-type Ca2+ channel blockers. After pretreatment with 10 microM nonylphenol, 1 microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor) failed to induce [Ca2+]i rises. Inhibition of phospholipase C with 2 microM U73122 did not change nonylphenol-induced [Ca2+]i rises. The nonylphenol-induced [Ca2+]i rises were enhanced or inhibited by phorbol myristate acetate or GF 109203X, respectively. At concentrations of 10 and 20 microM nonylphenol killed 55% and 100% cells, respectively. The cytotoxic effect of 10 microM nonylphenol was unaltered by pre-chelating cytosolic Ca2+ with BAPTA. Collectively, in MG63 cells, nonylphenol induced [Ca2+]i rises by causing Ca2+ release from intracellular stores and Ca2+ influx from extracellular space. Furthermore, nonylphenol can cause Ca2+-unrelated cytotoxicity in a concentration-dependent manner.

Nonylphenol-induced thymocyte apoptosis is related to Fas/FasL pathway

Nonylphenol (NP) is the final biodegradation product of nonylphenol polyethoxylates, which are widely used as surfactants in domestic and industrial products. NP has been reported to have estrogenic activity and shown to have potential reproductive toxicity. However, its influence on immune system function remains unclear. In this study, to determine the immunological effects of NP, the effects of NP on apoptosis and Fas/FasL gene expression in rat thymocyte in vitro were investigated. Thymocytes were treated with NP 0.1, 1, and 10 ppm, respectively. Viable cell numbers were determined by MTT assay. Apoptotic cells were identified by DNA fragment analysis. A semi-quantitative reverse transcriptase-polymerase chain reaction method was used to analyze Fas and FasL mRNA levels. Fas and FasL protein expression was evaluated by flow cytometry. The results showed that NP decreased the cellularity; induced apoptotic death and enhanced the expression of Fas and FasL mRNA as well as proteins in thymocytes. These findings suggest that NP may induce apoptosis by altering the expression of Fas and FasL in thymocytes so as to affect the immune system function.

Calcium-mediated aponecrosis plays a central role in the pathogenesis of estrogenic chemical-induced neurotoxicity

Estrogen is traditionally associated with females but is also present in males, and influences aspects of brain chemistry and brain morphology in males, females and also during prenatal development. Humans as well as animals are additionally exposed to environmental products that mimic estrogen activity, also known as endocrine disrupters (EDCs). This hypothesis article investigates the role of estrogen (and also EDCs) in the brain and how it influences the Ca2+ pathway. Ca2+ and its movement in and out of the cell is an extremely important ion controlling normal cell physiology. Any dysfunction in the movement from outside to inside the cell or between organelles may have fundamentally negative effects and the disturbance may even lead to apoptosis and/or necrosis. Therefore we consider whether estrogen and EDCs may alter the Ca2+ physiology and whether these changes may be one of the main causes of interference in physiology that is seen when humans and animals are exposed to EDCs. We come to the conclusion that on a molecular level Ca2+ and Ca2+ fluxes ([Ca2+]i, endocrine disrupting chemicals, redox modulation, mitochondria and cytochrome c followed by apoptosis, necrosis or most likely aponecrosis may contribute to chemical-mediated developmental toxicity. Similarly, we hypothesize that calcium-mediated aponecrosis do not only play a central role in the pathophysiology of estrogenic chemical-induced neurotoxicity, but can contribute to chemical-mediated developmental toxicity in general, thereby affecting almost all cells and organs of the living organism.

GM1 ganglioside-mediated accumulation of amyloid β-protein on cell membranes

The conversion of soluble, nontoxic amyloid beta-protein (Abeta) to aggregated, toxic Abeta is the key step in the development of Alzheimer's disease. Liposomal studies proposed that Abeta specifically recognizes a cholesterol-dependent cluster of monosialoganglioside GM1 and a conformationally altered form of Abeta promotes the aggregation of the protein. In this study, the accumulation of Abeta on living cells was investigated for the first time. The interaction of fluorescein-labeled Abeta (FL-Abeta) with rat pheochromocytoma PC12 cells was visualized using confocal laser microscopy. FL-Abeta was found to colocalize with GM1-rich domains on cell membranes and to accumulate in a concentration- and time-dependent manner, leading to cytotoxicity. Cholesterol depletion significantly reduced Abeta accumulation. These observations corroborate the GM1-mediated Abeta accumulation model.