Nonylphenol‐induced apoptotic pathways in SCM1 human gastric cancer cells

Environmental chemicals may affect human health by disrupting endocrine function. Many endocrine disrupting chemicals (EDCs) are estrogen‐like molecules that are classified as xenoestrogens (XEs). One XE, nonylphenol, is used as a surfactant or plasticizer and exhibits biotoxicity when accumulated in the body via the food chain. The aim of the present study was to clarify the role of nonylphenol‐induced SCM1 apoptosis by measuring cultured human gastric cancer cell (SCM1) death. Using WST‐1 reduction and propidium iodide‐staining assays, nonylphenol treatment was found to activate caspase‐3 and mitogen‐activated protein kinases (MAPKs), major markers in apoptotic pathways. Nonylphenol also activated the phosphorylation of extracellular signal‐regulated kinase (ERK), c‐Jun NH_2‐terminal kinase (JNK), and p38 mitogen‐activated protein kinase (p38 MAPK). However, only SB203580 (a p38MAPK inhibitor) partially inhibited nonylphenol‐induced apoptosis. Nonylphenol induced a [Ca²⁺]_i rise by causing extracellular Ca²⁺ influx and intracellular Ca²⁺ release from the endoplasmic reticulum, and its effects on SCM1 cell death were prevented by pretreatment with the Ca²⁺ chelator BAPTA/AM. These results suggest that nonylphenol caused Ca²⁺‐dependent apoptosis via the activation of p38 MAPK‐associated caspase‐3 in SCM1 cells. Drug Dev Res 2009. © 2009 Wiley‐Liss, Inc.     

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.     

Nonylphenol‐induced apoptotic cell death in mouse TM4 Sertoli cells via the generation of reactive oxygen species and activation of the ERK signaling pathway

Nonylphenol (NP), a representative endocrine disruptor, interferes with reproductive function in aquatic organisms and animals. Although many previous studies have focused on apoptotic cell death by NP, the fundamental mechanism of NP on apoptosis remains poorly understood. Here, we investigated the molecular mechanism on NP‐induced apoptotic cell death in mouse TM4 Sertoli cells. To evaluate NP treatment on cell viability, formazan and lactate dehydrogenase (LDH) assays were performed. Results indicate that NP reduced cell viability and increased the release of LDH in dose‐ and time‐dependent manners. The reduction of cell viability by NP treatment appeared to involve necrosis as well as apoptosis based on nuclear fragmentation, an increase in the sub G1 population, and the detection of poly(ADP ribose) polymerase and caspase‐3 cleavage. Additionally, the anti‐apoptotic protein Bcl‐2 diminished, whereas the pro‐apoptotic protein Bax increased in a time‐dependent manner. Note that NP‐induced apoptotic cell death was enhanced by the generation of reactive oxygen species (ROS) and activation of extracellular signal‐regulated kinase (ERK) signaling. Pretreatment with N‐acetylcysteine, an antioxidant, attenuated NP‐induced apoptotic cell death. Moreover, NP caused a transient activation of the MAPK pathway. In particular, NP‐induced cell death was significantly suppressed by U0126, a specific inhibitor of ERK. Taken together, our results suggest that NP induces apoptosis in mouse TM4 Sertoli cells via ROS generation and ERK activation. Copyright © 2013 John Wiley & Sons, Ltd.     

Nonylphenol‐induced cytosolic Ca2+ elevation and death in renal tubular cells

Nonylphenol is an environmental endocrine disrupter. The effect of nonylphenol on intracellular free Ca²⁺ levels ([Ca²⁺]_i) and viability in Madin‐Darby canine kidney (MDCK) cells was explored. Nonylphenol increased [Ca²⁺]_i in a concentration‐dependent manner (EC₅₀～0.8 μM). Nonylphenol‐induced Mn²⁺ entry demonstrated Ca²⁺ influx and removal of extracellular Ca²⁺ partly decreased the [Ca²⁺]_i rise. The [Ca²⁺]_i rise was inhibited by the protein kinase C activator, phorbol 13‐myristate acetate (PMA) but not by L‐type Ca²⁺ channel blockers. In Ca²⁺‐free medium, nonylphenol‐induced [Ca²⁺]_i rise was partly inhibited by pretreatment with 1 μM thapsigargin (an endoplasmic reticulum Ca²⁺ pump inhibitor). Conversely, nonylphenol pretreatment abolished thapsigargin‐induced Ca²⁺ release. Nonylphenol‐induced Ca²⁺ release was unaltered by inhibition of phospholipase C. At concentrations of 5–100 μM, nonylphenol killed cells in a concentration‐dependent manner. The cytotoxic effect of 100 μM nonylphenol was not affected by preventing [Ca²⁺]_i rises with BAPTA/AM. Collectively, this study shows that nonylphenol induced [Ca²⁺]_i increase in MDCK cells via evoking Ca²⁺ entry through protein kinase C‐regulated Ca²⁺ channels, and releasing Ca²⁺ from endoplasmic reticulum and other stores in a phospholipase C‐independent manner. Nonylphenol also killed cells in a Ca²⁺‐independent fashion. Drug Dev Res, 2009. © 2009 Wiley‐Liss, Inc.     

Diethyl phthalate enhances expression of SIRT1 and DNMT3a during apoptosis in PC12 cells

Diethyl phthalate (DEP) works as a phthalate plasticizer and is ubiquitously used in personal care products, cosmetics, medical equipment and pharmaceutical coating. DEP is considered a potential endocrine disruptor. Previously we found DEP‐enhanced apoptosis induced by serum deprivation in PC12 cells. However, the relationship between DEP and longevity‐related factors, sirtuins and epigenetic factors (e.g. DNA methyltransferases) remains unclear, because genome modification caused by chemical toxicity, sirtuins and epigenetic factors have played key roles in abnormal metabolism and development. Here, we investigate whether DEP affects sirtuins (SIRT1 and SIRT2) and methyltranferases (DNMT1 and DNMT3a) on the apoptosis of PC12 cells. We found that DNMT3a was significantly decreased by serum deprivation. However, DNMT3a, DNMT3b and SIRT1 were significantly increased under the enhancement of apoptosis induced by serum deprivation. These results suggest that SIRT1, DNMT3a and DNMT3b play multiple and complex roles in different apoptotic stages. Our results showed DEP triggered epigenetic factors on PC12 cells apoptosis under nutrition stress. Finally, our results suggest that monitoring epigenetic factors such as DNMT3a, DNMT3b and SIRT1 could be a useful tool for chemical toxicity risk assessment. Copyright © 2012 John Wiley & Sons, Ltd.     

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.     

Downregulation of steroid hormone receptor expression and activation of cell signal transduction pathways induced by a chiral nonylphenol isomer in mouse sertoli TM4 cells

Nonylphenols (NPs) are considered as important environmental toxicants and potential endocrine disrupting compounds which can disrupt male reproductive system. 4‐[1‐Ethyl‐1‐methylhexy] phenol (4‐NP₆₅) is one of the main isomers of technical nonylphenol mixtures. In the present study, effect of NPs was evaluated from an isomer‐specific viewpoint using 4‐NP₆₅. Decreased mRNA expression levels of estrogen receptor (ER)‐α, ER‐β, androgen receptor (AR) and progesterone receptor (PR) were observed in the cells exposed to 4‐NP₆₅ for 24 h. Furthermore, 4‐NP₆₅ treatment evoked significant decrease in protein expression levels of ER‐α and ER‐β. Levels of mullerian inhibiting substance and transferrin were found to change significantly in 4‐NP₆₅ challenged cells. Additionally, JNK1/2‐MAPK pathway was activated due to 4‐NP₆₅ exposure, but not ERK1/2 and p38‐MAPK pathways. Meanwhile, 4‐NP₆₅ increased the p‐Akt level and showed no effects on the Akt level which indicated that Akt pathway was activated by 4‐NP₆₅. In conclusion, these findings have shown that 4‐NP₆₅ exposure affected expression of cell receptors and cell signaling pathways in Sertoli TM4 cells. We proposed that molecular mechanism of reproductive damage in Sertoli cells induced by NPs may be mediated by cell receptors and/or cell signal transduction pathways, and that the effects were dependent on the side chain of NP isomers. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 469–476, 2017.     

Inhibition of serum deprivation-induced PC12 cell apoptosis by tanshinone II A.

AIM: To study the effect of tanshinone II A (Tan II A) on PC12 cell apoptosis induced by serum deprivation. METHODS: PC12 cell survival was measured by MTT assay. The DNA content and percentage of apoptosis were monitored by flow cytometry and DNA fragmentation was analyzed by agarose gel electrophoresis. RESULTS: Serum-free (12 h) medium induced apoptosis in PC12 cells. When the cells had been treated with Tan II A (0.1 and 1 micromol . L-1) for 12 h, the percentage of PC12 cell apoptosis was greatly decreased to 25.71 % and 4.89 % from 96.07 % in serum deprivation alone group, and DNA fragmentation was prevented. Tan II A (0.01 - 10 micromol . L-1) attenuated the cytotoxic effect of sodium cyanide (20 mmol . L-1), glutamate (0.5 mmol . L-1), and sodium nitroprusside (0.5 mmol . L-1). CONCLUSION: Tan II A prevented PC12 cells from apoptosis induced by serum-free medium.     

Daidzin protects PC12 cells from serum deprivation-induced apoptosis

This article examines the effect of daidzin on PC12 cell apoptosis induced by serum-free medium. PC12 cell survival was measured by MTT assay. The DNA content and percentage of apoptosis were monitored by flow cytometry and DNA fragmentation was analyzed by agarose gel electrophoresis. The results showed that serum-free (12 h) medium induced apoptosis in PC12 cells. When the cells had been treated with daidzin (0.1, 1 w M) for 12 h, the percentage of PC12 cell apoptosis was significantly decreased to 12.21 and 4.24% from 91.94% in the group with serum deprivation, and DNA fragmentation was prevented. Daidzin (0.01-10 w M) attenuated the cytotoxic effect of sodium cyanide (20 mM), glutamate (0.5 mM) and sodium nitroprusside (0.5 mM) in a manner dependent on concentration. The results suggested that daidzin prevented PC12 cell from serum free-induced apoptosis.     

Stevioside enhances apoptosis induced by serum deprivation in PC12 cells

In the laboratory, using a PC12 cell system, studies have been conducted on the effects of various chemicals on apoptosis, as it is considered to be an essential part of normal development, maintenance, and defense in organisms. Stevioside is a natural sweetener extracted from the leaves of Stevia rebaudiana. Since it is widely used as a sugar replacement, it was decided to evaluate the toxicological effects of low concentrations of stevioside on apoptosis induced by serum deprivation using the PC12 cell system. It was found that based on data from DNA electrophoresis and TUNEL signal assays stevioside enhanced apoptosis induced by serum deprivation. This enhancement was caused by increased expression of Bax and of cytochrome c released into the cytosol. These findings suggest that stevioside affects the regulation of the normal apoptotic condition. Further investigation will be needed to clarify the detailed mechanism of the enhancement due to the treatment with stevioside.     

Daidzin protects PC12 cells from serum deprivation-induced apoptosis

This article examines the effect of daidzin on PC12 cell apoptosis induced by serum-free medium. PC12 cell survival was measured by MTT assay. The DNA content and percentage of apoptosis were monitored by flow cytometry and DNA fragmentation was analyzed by agarose gel electrophoresis. The results showed that serum-free (12 h) medium induced apoptosis in PC12 cells. When the cells had been treated with daidzin (0.1, 1 μM) for 12 h, the percentage of PC12 cell apoptosis was significantly decreased to 12.21 and 4.24% from 91.94% in the group with serum deprivation, and DNA fragmentation was prevented. Daidzin (0.01-10 μM) attenuated the cytotoxic effect of sodium cyanide (20 mM), glutamate (0.5 mM) and sodium nitroprusside (0.5 mM) in a manner dependent on concentration. The results suggested that daidzin prevented PC12 cell from serum free-induced apoptosis.     

Stevioside enhances apoptosis induced by serum deprivation in PC12 cells

In the laboratory, using a PC12 cell system, studies have been conducted on the effects of various chemicals on apoptosis, as it is considered to be an essential part of normal development, maintenance, and defense in organisms. Stevioside is a natural sweetener extracted from the leaves of Stevia rebaudiana. Since it is widely used as a sugar replacement, it was decided to evaluate the toxicological effects of low concentrations of stevioside on apoptosis induced by serum deprivation using the PC12 cell system. It was found that based on data from DNA electrophoresis and TUNEL signal assays stevioside enhanced apoptosis induced by serum deprivation. This enhancement was caused by increased expression of Bax and of cytochrome c released into the cytosol. These findings suggest that stevioside affects the regulation of the normal apoptotic condition. Further investigation will be needed to clarify the detailed mechanism of the enhancement due to the treatment with stevioside.     

Prostate apoptosis response-4 involved in the protective effect of salvianolic acid B against amyloid beta peptide-induced damage in PC12 cells

To observe the effect of salvianolic acid-B (SalB) against the cytoxicity of amyloid beta peptide (A-beta)(25-35) to PC12 cells, the cells were incubated with A-beta, and the cytoxicity was investigated by MTT, flow cytometry and a cell free apoptotic system. The expression of prostate apoptotic response-4 (Par-4) was detected by Western blot. Aged A-beta 10 micromol/L significantly inhibited the MTT reduction of PC12 cells, SalB1 micromol/L inhibited the toxicity induced by A-beta. In flow cytometric analysis, PC12 cells treated with A-beta exhibited degraded DNA content characteristic of apoptosis cells (1.53% vs 19.9%). PC12 cells pretreated with SalB (10 nmol/L, 100 nmol/L, 1 micromol/L) manifested relatively low proportion of apoptosis (15.7%, 13.5%, 11.8%, respectively). SalB (10 nmol/L - 1 micromol/L) when added at the beginning of the cell free apoptotic reaction had no apparent effect on the nuclei apoptosis. Pretreatment of PC12 cells with SalB largely prevented the increase in Par-4 expression of the cells when they were exposed to A-beta. The results suggest that Par-4 is involved in the protective effect of SalB against A-beta-induced damage in PC12 cells.     

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.     

二氮嗪对氧糖剥夺后PC12细胞凋亡及对Bcl-2蛋白的影响

目的探讨二氮嗪对氧糖剥夺(OGD)PC12细胞凋亡的保护作用及其机制。方法体外培养PC12细胞株,以OGD、二氮嗪、5-羟葵酸(5-HD)处理,分为A组(正常对照组),B组(氧糖剥夺组),C组(氧糖剥夺+二氮嗪组),D组(氧糖剥夺+二氮嗪组+5-HD组),采用Annexin V-FITC/PI双染流式细胞分析仪检测凋亡率,应用免疫荧光染色和Western blot检测Bcl-2蛋白表达水平,观察二氮嗪对氧糖剥夺PC12细胞凋亡的保护作用。结果氧糖剥夺后B,C,D组PC12细胞凋亡细胞数增加,C组与B、D组比较差异均有显著性(P<0.01)。B,C,D组Bcl-2蛋白表达增加,C组达到高峰。C组与A、B、D组比较差异均有显著性(P<0.01)。结论二氮嗪能抑制氧糖剥夺PC12细胞凋亡,这一作用机制可能是增加Bcl-2表达来实现其保护作用的。     

Comparative toxicological evaluation of nonylphenol and nonylphenol polyethoxylates using human keratinocytes

Nonylphenol polyethoxylates (NPEOs) are a major group of nonionic surfactants widely used in various detergents, cleaners, plastics, papers, and agro-chemical products. Nonylphenol (NP), which is a final degraded metabolite derived from NPEOs, has been reported as an endocrine disrupter, known to mimic or disturb reproductive hormone functions. Concern about the hazards of NP and NPEOs has generated legal restrictions and action plans worldwide. Considering the fact that NP and NPEOs are majorly used in the production of products such as detergents, shampoos, and cosmetics which frequently come into contact with the skin, we investigated the effects of NP and NPEOs on a human keratinocyte cell line (HaCaT). In this study, the toxicity of NP and NPEOs was screened in HaCaT cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide thiazolyl blue assay and Western blotting. The potential cytotoxicity of substitutes was assessed by dose-response assays, relative cell viability, and genotoxicity caused by specific alterations in DNA damage response proteins (including ataxia-telangiectasia mutated, p53, Chk1, Chk2, and Histone H2A.X). We demonstrated that NP and NPEOs are toxic to HaCaT cells, as revealed by the decreased cell viability after 24?h treatment. NPs and NPEOs also induced apoptosis and DNA damage as shown by the activation of Poly(ADP-ribose) polymerase, Caspase-3, and Histone H2A.X.     

Deoxynivalenol induces apoptosis in PC12 cells via the mitochondrial pathway

Deoxynivalenol (DON) has broad toxicity in animals and humans. In this study the impact of DON treatment on apoptotic pathways in PC12 cells was determined. The effects of DON were evaluated on (i) typical indicators of apoptosis, including cellular morphology, cell activity, lactate dehydrogenase (LDH) release, and apoptosis ratio in PC12 cells, and on (ii) the expression of key genes and proteins related to apoptosis, including Bcl-2, Bax, Bid, cytochrome C (Cyt C), apoptosis inducing factor (AIF), cleaved-Caspase9, and cleaved-Caspase3. DON treatment inhibited proliferation of PC12 cells, induced significant morphological changes and apoptosis, promoted the release of Cyt C and AIF from the mitochondria, and increased the activities of cleaved-Caspase9 and cleaved-Caspase3. Bcl-2 expression decreased with increasing DON concentrations, in contrast to Bax and Bid, which were increased with increasing DON concentration. These data demonstrate that DON induces apoptosis in PC12 cells through the mitochondrial apoptosis pathway.     

瓜子金皂苷己对连二亚硫酸钠致氧糖剥夺/复供诱导PC12细胞凋亡的抑制作用

目的观察瓜子金皂苷己(polygalasaponin F,PGSF)对氧糖剥夺/复供(oxygen-glucose deprivation and reperfusion,OGD/R)所诱导的PC12细胞凋亡的作用及其机制。方法以连二亚硫酸钠合并无糖Earle’s液造成氧糖剥夺,继而恢复为完全培养基以建立体外OGD/R模型,以Hoechst33342/PI双染及流式细胞术观察细胞受损和凋亡情况;以JC-1荧光染色法测定细胞线粒体膜电位(mitochondrial membranepotential,MMP);以Western blot法检测凋亡相关蛋白的表达。结果 PGSF可明显改善细胞形态并降低细胞受损和凋亡百分率,抑制MMP水平的降低,增加Bcl-2/Bax表达比值。结论 PGSF对OGD/R诱导的PC12细胞凋亡具有明显抑制作用,机制与其调节Bcl-2和Bax的表达及稳定MMP有关。