P38 and ERK mitogen-activated protein kinases mediate acrolein-induced apoptosis in Chinese hamster ovary cells

Chronic lead poisoning-induced budgerigar liver damage, gut microbiota dysbiosis, and metabolic disorder

Birds are sensitive to heavy metal pollution, and lead (Pb) contamination can negatively affect their liver and gut. Therefore, we used budgerigars to examine liver and gut toxicosis caused by Pb exposure in bird, and the possible toxic mechanisms. The findings showed Pb exposure increased liver weight and decreased body weight. Moreover, histopathological and immunofluorescence assay results demonstrated obvious liver damage and cell apoptosis increased in Pb- treated budgerigars. Quantitative polymerase chain reaction (qPCR) results also showed Pb caused an increase in apoptosis by inhibiting the PPAR-γ/PI3K/Akt pathway. The gut microbe analyses indicated Firmicutes, Proteobacteria, and Bacteroidetes were dominant microbial phyla, and Network analysis results shown Arthrobacter, Bradyrhizobium and Alloprevotella as the hubs of Modules I, II, and III, respectively. Phenylpropanoids and polyketides, Organoheterocyclic compounds, Organic oxygen compounds, and Organic nitrogen compounds were dominant metabolite superclasses. Tauroursodeoxycholic acid, taurochenodeoxycholic acid (sodium salt), and 2-[2-(5-bromo-2-pyridyl)diaz-1-enyl]-5-(diethylamino)phenol were significantly enriched in the Pb-treated group. It showed that 41 Kyoto Encyclopedia of Genes and Genomes (KEGG) orthologues and 183 pathways differed between the Pb-treated and control budgerigars using microbial and metabolomic data. Moreover, orthogonal partial least-squares discrimination analysis (OPLS-DA) based on microbial and metabolite indicated distinct clusters in the Pb-treated and control groups. Additionally, the correlation analysis results indicated that a positive correlation for the Pb-treated and control groups between gut microbiota and metabolomic data, respectively. Furthermore, the microenvironment of the gut and liver were found to affect each other, and this study demonstrated heavy metal especially Pb may pose serious health risks to birds through the "gut-liver axis" too.

Lead exposure induced developmental nephrotoxicity in Japanese quail (Coturnix japonica) via oxidative stress-based PI3K/AKT pathway inhibition and NF-κB pathway activation

Birds are sensitive to environmental pollution and lead (Pb) contamination could negatively affect nearly all avian organs and systems including kidney of excretive system. Thereby, we used a biological model species-Japanese quail (Coturnix japonica) to examine the nephrotoxic effects of Pb exposure and possible toxic mechanism of Pb on birds. Quail chicks of 7-day-old were exposed to 50 ppm Pb of low dose and high dose of 500 ppm and 1000 ppm Pb in drinking water for five weeks. The results showed that Pb exposure induced kidney weight increase while body weight and length reduction. The increase of uric acid (UA), creatinine (CREA) and cystatin c (Cys C) in the plasma suggested renal dysfunction. Moreover, both microstructural and ultrastructural changes demonstrated obvious kidney damages. In particular, renal tubule epithelial cells and glomeruli swelling indicated renal inflammation. Furthermore, changes in the content and activity of oxidative stress markers suggested that Pb caused excessive oxidative stress in the kidney. Pb exposure also induced abnormal apoptosis in the kidney. In addition, RNA sequencing (RNA-Seq) analysis revealed that Pb disturbed molecular pathways and signaling related with renal function. Especially, Pb exposure resulted in an increase in renal uric acid synthesis by disrupting purine metabolism. Pb caused apoptotic increment by inhibiting the phosphatidylinositol-3-kinase (PI3K)/RAC-alpha serine/threonine-protein kinase (AKT) pathway and induced aggravated inflammation by activating Nuclear Factor kappa B (NF-κB) signaling pathway. The study implied that Pb caused nephrotoxicity through structural damages, uric acid metabolism disorder, oxidation imbalance, apoptosis and inflammatory pathway activation.

Tannic acid attenuate AKT phosphorylation to inhibit UMUC3 bladder cancer cell proliferation

Urothelial bladder cancer is rapidly spreading across Western countries, and therapy has shown little-to-moderate effects on bladder cancer. Thus, focusing on curbing cancer incidence has become crucial. The aim of the present study was to investigate the anticancer effects of Tannic acid (TA) in human bladder cancer. UMUC3 bladder cancer cells were treated with different concentrations of TA (0-100 µM) and tested for cell viability, colony formation, and apoptosis. The involvement of the phosphoinositide-3 kinase (PI3K)/Akt pathway in the action of TA was examined. TA treatment significantly inhibited the viability and increased percentage of apoptotic cells, thereby decreasing antiapoptotic proteins (BCL2, MCL-1, and BCL-XL) expression, resulting in the Caspase-3 activation. TA treatment decreased stem cell markers expression such as SOX2, OCT4, and NANOG. Additionally, TA treatment significantly reduced the phosphorylation levels of Akt in bladder cancer cells. Our study demonstrates the growth inhibitory effects of TA in bladder cancer cells, and highlights its potential as an anticancer agent for bladder cancer.

The Effect of Yiqi Huoxue Tongluo Decoction on Spinal Cord Microglia Activation and ASK1-MKK3-p38 Signal Pathway in Rats with Diabetic Neuropathic Pain

Diabetic neuropathic pain (DNP) is one of the most common chronic peripheral neuropathies in diabetes mellitus (DM). Objective. To observe the underlying mechanism of the effects of Yiqi Huoxue Tongluo Decoction (YQHX) on DNP rats. Methods. SD rats were intraperitoneally injected with 35 mg/kg streptozotocin (STZ) to prepare DNP models and were treated with YQHX for 8 weeks. Results. Studies have shown that the drug restores some levels of MWT, TWL, and MNCV, downregulates the levels of inflammatory factors IL-6, IL-1β, and TNF-α, downregulates the levels of ASK1-MKK3-p38, and weakens the level of OX42 activation. Conclusion. Yiqi Huoxue Tongluo Decoction can relieve DNP by affecting the activity of spinal cord microglia and the ASK1-MKK3-p38 signaling pathway, thereby reducing the central sensitization caused by the inflammatory response of DNP rats.

MAPK Signaling Pathway Is Essential for Female Reproductive Regulation in the Cabbage Beetle, Colaphellus bowringi

The mitogen-activated protein kinase (MAPK) signaling pathway is a well-conserved intracellular signal transduction pathway, and has important roles in mammalian reproduction. However, it is unknown whether MAPK also regulates insect reproductive mechanisms. Therefore, we investigated the role of the MAPK signaling pathway in ovarian growth and oviposition in the cabbage beetle Colaphellus bowringi, an economically important pest of Cruciferous vegetables. As an initial step, 14 genes from the extracellular regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 MAPK (P38) cascades were knocked down using RNA interference (RNAi). The results revealed that RNAi knockdown of MAPK-ERK kinase (MEK), ERK, Kinase suppressor of RAS 2 (KSR2), and P38 induced ovarian development stagnation, low fecundity, and decreased longevity, which indicate that ERK and P38 signaling pathways are important for female C. bowringi survival and reproduction. The potential regulatory role of ERK and P38 pathways in the female reproductive process was investigated using quantitative real-time PCR. We found that ERK pathway possibly regulated ecdysone biosynthesis and P38 pathway possibly involved in the germline stem cell (GSC) development and differentiation. Our findings demonstrated the importance of the MAPK signaling pathway in the female reproduction of insects, and further enhanced the molecular mechanism of female reproductive regulation in insects.

A novel protective role of sacubitril/valsartan in cyclophosphamide induced lung injury in rats: impact of miRNA-150-3p on NF-κB/MAPK signaling trajectories

Cyclophosphamide (CP) is a chemotherapeutic agent that induces oxidative stress causing multiple organ damage. Sacubitril/valsartan, is a combined formulation of neprilysin inhibitor (sacubitril) and angiotensin II receptor blocker (valsartan), that induces the protective effect of brain natriuretic peptide. The aim of the current study is to investigate the prophylactic impacts of sacubitril/valsartan versus valsartan against CP-induced lung toxicity in rats. Rats were assigned randomly into 6 groups; control; received corn oil (2 ml/kg/day; p.o. for 6 days), sacubitril/valsartan (30 mg/kg; p.o. for 6 days), valsartan (15 mg/kg; p.o. for 6 days), CP (200 mg/kg; i.p. on day 5), sacubitril/valsartan + CP (30 mg/kg; p.o. for 6 days, 200 mg/kg; i.p. single dose on day 5, respectively), valsartan + CP (15 mg/kg; p.o. for 6 days, 200 mg/kg; i.p. single dose on day 5, respectively). Both sacubitril/valsartan and valsartan produced a significant decrease in the inflammation and fibrosis markers in the BALF, in comparison with the CP group. Both sacubitril/valsartan and valsartan produced an apparent decrease in the relative genes expression of miR-150-3p and NF-κB, as well as a significant decrease in the relative expression of P38 and ERK1/2 MAPKs and an increase in the relative gene expression of Nrf-2, compared to CP group. Intriguingly, sacubitril/valsartan , showed subtle superiority in almost all investigated parameters, compared to valsartan. In conclusion, sacubitril/valsartan effectively abrogated the CP induced lung inflammation and fibrosis, providing a potential promising protection that could be linked to their ability to inhibit miR-150-3p via inhibition of NF-κB and MAPK signaling pathways.

Combined cell death of co-exposure to aldehyde mixtures on human bronchial epithelial BEAS-2B cells: Molecular insights into the joint action

Aldehydes are common air pollutants and metabolites of the organism, which widely exist in many in vivo (e.g. Alzheimer's disease) and in vitro (e.g. cigarette smoke) situations. Individual aldehydes have been studied well alone, while their combined toxicity is still obscure. Here, we examined the combined apoptosis of aldehyde mixtures in BEAS-2B cells at smoking-related environmental/physiologically relevant concentrations, and the potential mechanism was investigated further based on the related signaling pathway. Co-exposure to aldehyde mixtures demonstrated significant synergistic interaction on apoptosis in a concentration-dependent manner, which differed from the expectation based on single aldehydes. Moreover, formaldehyde significantly potentiated the induction of death receptor-5, caspase 8/10, cleaved caspase 3/7/9, pro-apoptotic proteins (Bim, Bad and Bax), depolarization of MMP (mitochondrial membrane potential) and AIF (apoptosis-inducing factor) induced by acrolein, and synergistically decreased expressions of pro-survival proteins (Bcl-2 and Bcl-XL) and poly ADP-ribose polymerase. Therefore, aldehyde mixture-induced synergistic apoptosis was mediated both by TRAIL death receptor and mitochondrial pathway. Additionally, reactive oxygen species, Ca²⁺ levels, DNA damage, and phosphorylated MDM2 were all synergistically induced by aldehyde mixtures, while total p53, phosphorylated p53 and phosphorylated AKT (serine/threonine kinase) were inhibited. Antioxidants N-acetylcysteine suppressed the aldehyde mixture-induced ROS, DNA damage and apoptosis, and blocked the TRAIL death receptor and mitochondrial pathway, while it did not rescue the p53 and AKT pathway. Briefly, aldehyde mixtures induced synergistic apoptosis even at smoking-related environmental/physiologically relevant concentrations, which could be enhanced through ROS-mediated death receptor/mitochondrial pathway, and the down-regulation of phosphorylated AKT.

Anti-inflammatory Effect of AZD6244 on Acrolein-Induced Neuroinflammation

Clinically, high levels of acrolein (a highly reactive α, β-unsaturated aldehyde) and acrolein adducts are detected in the brain of patients with CNS neurodegenerative diseases, including Alzheimer's disease and spinal cord injury. Our previous study supports this notion by showing acrolein as a neurotoxin in a Parkinsonian animal model. In the present study, the effect of AZD6244 (an ATP non-competitive MEK1/2 inhibitor) on acrolein-induced neuroinflammation was investigated using BV-2 cells and primary cultured microglia. Our immunostaining study showed that lipopolysaccharide (LPS, an inflammation inducer as a positive control) increased co-localized immunoreactivities of phosphorylated ERK and ED-1 (a biomarker of activated microglia) in the treated BV-2 cells. Similar elevation in co-localized immunoreactivities of phosphorylated ERK and ED-1 was detected in the acrolein-treated BV-2 cells. Furthermore, Western blot assay showed increases in phosphorylated ERK in BV-2 cells subjected to LPS (1 μg/mL) or acrolein (30 μM); these increases were blocked by AZD6244 (10 μM). At the same time, AZD6244 attenuated LPS-induced TNF-α (a pro-inflammatory cytokine) and cyclooxygenase-II (COX II, a pro-inflammatory enzyme). Consistently, AZD6244 reduced acrolein-induced elevations in COX-II mRNA and COX-II protein expression. In addition, AZD6244 inhibited acrolein-induced increases in activated caspase 1 (a biomarker of inflammasome activation) and heme oxygenase-1 (a redox-regulated chaperone protein) in BV-2 cells. Using a transwell migration assay, AZD6244 attenuated acrolein (5 μM)-induced migration of BV-2 cells and primary cultured microglia. In conclusion, our study shows that acrolein is capable of inducing neuroinflammation which involved ERK activation in microglia. Furthermore, AZD6244 is capable of inhibiting acrolein-induced neuroinflammation. Our study suggests that ERK inhibition may be a neuroprotective target against acrolein-induced neuroinflammation in the CNS neurodegenerative diseases.

Clock-Bmal1 mediates MMP9 induction in acrolein-promoted atherosclerosis associated with gut microbiota regulation

Circadian rhythm is believed to play important roles in atherosclerosis. The gut microbiota is found to be closely related to atherogenesis, and shows compositional and functional circadian oscillation. However, it's still unclarified whether circadian clock and intestinal microbiota are involved in the progression of atherosclerosis induced by environmental pollutant acrolein. Herein, patients with atherosclerosis showed higher MMP9, a promising biomarker for atherosclerosis, and lower Bmal1 and Clock expression in the plasma. Interestingly, acrolein exposure contributed to the increased MMP9, decreased Clock and Bmal1, and activated MAPK pathways in human umbilical vein endothelial cells (HUVECs). We found that knockdown of Clock or Bmal1 lead to upregulation of MMP9 in HUVECs, and that Clock and Bmal1 expression was elevated while MAPK pathways were blocked. Atherosclerotic apolipoproteinE-deficient mice consumed a high-fat diet were used and treated with acrolein (3 mg/kg/day) in the drinking water for 12 weeks. Upregulation of MMP9, and downregulation of Clock and Bmal1 were also observed in plasma of the mice. Besides, acrolein feeding altered gut microbiota composition at a phylum level especially for an increased Firmicutes and a decreased Bacteroidetes. Additionally, gut microbiota showed correlation with atherosclerotic plaque, MMP9 and Bmal1 levels. Therefore, our findings indicated that acrolein increased the expression of MMP9 through MAPK regulating circadian clock, which was associated with gut microbiota regulation in atherosclerosis. Circadian rhythms and gut microbiota might be promising targets in the prevention of cardiovascular disease caused by environmental pollutants.

Acrolein-mediated alpha-synuclein pathology involvement in the early post-injury pathogenesis of mild blast-induced Parkinsonian neurodegeneration

Survivors of blast-induced traumatic brain injury (bTBI) have increased susceptibility to Parkinson's disease (PD), characterized by α-synuclein aggregation and the progressive degeneration of nigrostriatal dopaminergic neurons. Using an established bTBI rat model, we evaluated the changes of α-synuclein and tyrosine hydroxylase (TH), known hallmarks of PD, and acrolein, a reactive aldehyde and marker of oxidative stress, with the aim of revealing key pathways leading to PD post-bTBI. Indicated in both animal models of PD and TBI, acrolein is likely a point of pathogenic convergence. Here we show that after a single mild bTBI, acrolein is elevated up to a week, systemically in urine, and in whole brain tissue, specifically the substantia nigra and striatum. Acrolein elevation is accompanied by heightened α-synuclein oligomerization, dopaminergic dysregulation, and acrolein/α-synuclein interaction in the same brain regions. We further show that acrolein can directly modify and oligomerize α-synuclein in vitro. Taken together, our data suggests acrolein likely plays an important role in inducing PD pathology following bTBI by encouraging α-synuclein aggregation. These results are expected to advance our understanding of the long-term post-bTBI pathological changes leading to the development of PD, and suggest intervention targets to curtail such pathology.

Thymoquinone attenuates phosphorylation of AKT to inhibit kidney cancer cell proliferation

Thymoquinone (Tq) is an active compound from Nigella sativa which is used in traditional medicine. The effect of Tq on kidney cancer and the pathway of action remain unproven. Herein, we report the anticancer properties of Tq on kidney cancer cells. Tq demonstrated anti-proliferative effects in A498 cells with a GI₅₀ value of 40.07 µM and Caki-1 cells with a GI50 of 51.04 µM by the MTT assay. Tq exhibited nuclear fragmentation and inhibited trans-endothelial migration of A498 and Caki-1 cells in a dose-responsive manner. Time-dependent increase in Annexin V-positive cells and sub-G₀ /G₁ cell population was observed post-Tq treatment. The compound increased Bax protein levels and reduced Bcl-2 protein levels dose dependently in cells, thereby favoring apoptosis. Tq decreased the phosphorylation of Akt in both kidney cell types. The results suggest effective anticancer activity of Tq on kidney cancer cells which may be mediated by the Akt pathway. PRACTICAL APPLICATIONS: Results from the current investigation will through more light on the mechanistic pathway of Tq activity on the inhibition of kidney cancer cell proliferation. The output of this preclinical in vitro study may be translated into better chemotherapeutics of Tq and its analogs to treat kidney cancer. However, a detailed investigation on in vivo models is recommended.

Inhibition of MAPKs Signaling Pathways Prevents Acrolein-Induced Neurotoxicity in HT22 Mouse Hippocampal Cells

Activation of mitogen-activated protein kinases (MAPKs) in neurons may underlie the pathogenesis of Alzheimer's disease (AD). Acrolein, a ubiquitous pollutant, has been reported to implicate in the etiology of AD. Our previous data showed that acrolein changed the levels of key AD-associated proteins, including advanced glycation end products (RAGE), A-disintegrin and metalloprotease (ADAM-10), and beta-site amyloid-beta peptide cleaving enzyme 1 (BACE-1). In this study, we investigated whether acrolein-induced alterations of AD-associated proteins are relevant to MAPKs activation, and strategies to inhibit MAPKs activation yield benefits to acrolein-induced neurotoxicity in HT22 mouse hippocampal cells. We found that acrolein activated MAPKs signaling pathways to mediate cells apoptosis, and then altered the levels of AD-associated proteins ADAM-10, BACE-1 and RAGE. Inhibitors of MAPKs signaling pathways attenuated the cells death and restored the proteins levels of ADAM-10, BACE-1 and RAGE in varying degrees induced by acrolein. Taken together, activated MAPKs signaling pathways should be underlying the pathology of acrolein-induced neuronal disorders. Inhibitors of MAPKs pathways might be promising agents for acrolein-related diseases, such as AD.

Neuroprotective effect of polysaccharide separated from Perilla frutescens Britton var. acuta Kudo against H2O2-induced oxidative stress in HT22 hippocampus cells

This study was carried out to evaluate the neuroprotective activity of polysaccharide extracts isolated from Perilla frutescens (PEPF) in H₂O₂-treated HT22 hippocampus cells. The PEPF treatment was found to increase the anti-oxidant activities of HT22 hippocampus cells. PEPF treatment resulted in a significant protection of HT22 hippocampus cells against H₂O₂-induced neurotoxicity, this protection ultimately occurred through an inhibition of ROS-mediated intracellular Ca²⁺ levels leading to MAPKs and NF-κB, as well as the accumulation of PI3K/AKT and Nrf2-mediated HO-1/NQO1 pathways. Furthermore, PEPF not only decreased the expression of Bax, cytochrome c, and cleaved caspases-3, -8, and -9, but also increased the expression of PARP and Bcl-2 in the H₂O₂-treated HT22 hippocampus cells, which overall contributed to the neuroprotective action. PEPF retains its mitochondrial membrane potential and reduces the elevated levels of sub-G1 phase and apoptotic morphological features induced by H₂O₂. It also reduces the malondialdehyde levels and enhances the intracellular SOD activity.

Artocarpin, an isoprenyl flavonoid, induces p53-dependent or independent apoptosis via ROS-mediated MAPKs and Akt activation in non-small cell lung cancer cells

Artocarpin has been shown to exhibit cytotoxic effects on different cancer cells, including non-small cell lung carcinoma (NSCLC, A549). However, the underlying mechanisms remain unclear. Here, we explore both p53-dependent and independent apoptosis pathways in artocarpin-treated NSCLC cells. Our results showed that artocarpin rapidly induced activation of cellular protein kinases including Erk1/2, p38 and AktS473. Inhibition of these protein kinases prevented artocarpin-induced cell death. Moreover, artocarpin-induced phosphorylation of these protein kinases and apoptosis were mediated by induction of reactive oxygen species (ROS), as pretreatment with NAC (a ROS scavenger) and Apocynin (a Nox-2 inhibitor) blocked these events. Similarly, transient transfection of p47Phox or p91Phox siRNA attenuated artocarpin-induced NADPH oxidase activity and cell death. In addition, p53 dependent apoptotic proteins including PUMA, cytochrome c, Apaf-1 and caspase 3 were activated by artocarpin, and these effects can be abolished by antioxidants, MAPK inhibitors (U0126 and SB202190), but not by PI3K inhibitor (LY294002). Furthermore, we found that artocarpin-induced Akt phosphorylation led to increased NF-κB activity, which may act as an upstream regulator in the c-Myc and Noxa pathway. Therefore, we propose that enhancement of both ERK/ p38/ p53-dependent or independent AktS473/NF-κB/c-Myc/Noxa cascade by Nox-derived ROS generation plays an important role in artocarpin-induced apoptosis in NSCLC cells.

Synergistic action of cisplatin and echistatin in MDA-MB-231 breast cancer cells

The aim of our study was to determine whether the use of cisplatin in the presence echistatin in MDA-MB-231 breast cancer cells leads to a reduction of toxic effects associated with the use of cisplatin. The expression of β₁-integrin and insulin-like growth factor 1 receptor (IGF-IR), signaling pathway protein expression: protein kinase B (AKT), mitogen-activated protein kinases (ERK1/ERK2), nuclear factor kappa B (NFκB), and caspase-3 and -9 activity was measured after 24 h of incubation with tested compounds to explain detailed molecular mechanism of induction of apoptosis. The viability of MDA-MB-231 breast cancer cells was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Annexin V-FITC/propidium iodide staining assay was performed to detect the induction of apoptosis. Inhibition DNA biosynthesis was determined by [³H]thymidine incorporation into DNA. The expression of of β₁-integrin, IGF-IR, AKT, ERK1/ERK2, NFκB, caspase-3 and -9 was evaluated using Western blot. The results suggest that treatment of MDA-MB-231 breast cancer cells for 24 h cisplatin plus echistatin severely inhibits cell growth and activates apoptosis by upregulation of caspase-3 and -9 expressions. The effect was stronger than treatment cisplatin and echistatin alone. In this study, we have found that cisplatin plus echistatin treatment decreases collagen biosynthesis in MDA-MB-231 breast cancer cells stronger than the individual compounds. The inhibition was found to be dependent on the β₁-integrin and IGF receptor activation. A significant reduction of ERK1/ERK2, AKT expression in cancer cells after cisplatin plus echistatin treatment was also found. The cancer cells treated by echistatin, cisplatin, and in particular the combination of both compounds drastically increased expression of NFκB transcription factor. Our results suggest that combined therapy cisplatin plus echistatin is a possible way to improve selectiveness of cisplatin. This mechanism probably is due to downregulation of expression of β₁-integrin and IGF-IR receptors, and the signaling pathway proteins induced by these receptors. Our results suggest that therapy cisplatin plus echistatin is a possible way to improve selectiveness of cisplatin.

Mitogen-Activated Protein Kinases Are Activated in Placental Injury in Rat Model of Acute Pancreatitis in Pregnancy

OBJECTIVES

To establish a rat model of acute pancreatitis in pregnancy (APIP) and evaluate its general presentations, assess placental injury, and discuss possible mechanisms.

METHODS

The APIP rat model was induced by sodium taurocholate in Sprague-Dawley rats of later gestation. Normal and sham-operated (SO) rats in later gestation were set as controls, 3 time points were set in SO and APIP groups to determine optimal modeling time. Histological changes of pancreas and placenta were assessed. Placental injury was determined by immunohistochemistry stain of caspase-3. Serum levels of amylase, lipase, and Ca; proinflammatory cytokines as tumor necrosis factor-α, interleukin-1β (IL-1β), IL-6, and anti-inflammatory cytokine IL-10 by enzyme-linked immunosorbent assay; mitogen-activated protein kinases and their phosphorylated forms by Western blotting.

RESULTS

Pancreatic necrotizing and placental injury occurred in time-dependent patterns. Serum levels of amylase and lipase significantly increased but Ca decreased; tumor necrosis factor-α, IL-1β, IL-6, and IL-10 were all increased in the APIP group; c-Jun N-terminal kinase, p38, and ERK1/2 were activated but with different distributing patterns in the placenta.

CONCLUSIONS

Placental injury is involved in the rat model of APIP, and a modeling time of 6 hours is optimal and conducive to further studies; c-Jun N-terminal kinase and p38 may play important roles in placental injury during APIP.

Differential effects of bevacizumab, ranibizumab and aflibercept on cell viability, phagocytosis and mitochondrial bioenergetics of retinal pigment epithelial cell

PURPOSE

To evaluate the short- and long-term effects of most clinically used anti-vascular endothelial growth factor agents, including bevacizumab, ranibizumab or aflibercept, on cell viability, phagocytosis, mitochondrial bioenergetics and the oxidant acrolein-induced oxidative stress of human adult retinal pigment epithelial (ARPE)-19 cells.

METHODS

In cultured ARPE-19 cells, cell viability was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, phagocytotic activity and intracellular reactive oxygen species (ROS) level were determined by flow cytometry, mitochondrial bioenergetics was assessed using a Seahorse XF24 Extracellular Flux Analyzer, and protein expression was measured by Western blotting.

RESULTS

Long-term exposure to all three agents had no effect on cell viability; but rescued the ARPE-19 cells from acrolein-induced decrease in cell viability. Bevacizumab, but not ranibizumab or aflibercept, suppressed the phagocytotic activity of ARPE-19 cells and exerted significantly less protection against acrolein-induced inhibition of phagocytosis. Both ranibizumab and aflibercept increased basal respiratory rate and maximal mitochondrial respiratory capacity after 1-hr exposure; but returned to baseline following 24- or 72-hr exposure. In contrast, both responses were reduced on short-term exposure, but augmented after long-term exposure to bevacizumab. Long-term pretreatment with all three agents reversed acrolein-induced impairment of mitochondrial bioenergetics, overproduction of ROS and phosphorylation of the mitogen-activated protein kinases in ARPE-19 cells.

CONCLUSION

Bevacizumab might affect mitochondrial bioenergetics differently from that by ranibizumab and aflibercept. Ranibizumab and aflibercept at their therapeutic dose protect against acrolein-induced oxidative cytotoxicity in human ARPE-19 cells via an increase in mitochondrial bioenergetics. An early protective action on mitochondrial bioenergetic capacity might be used to predict possible long-term antioxidative effects of the agents in the eye.

Diallyl Disulfide Prevents Cyclophosphamide-Induced Hemorrhagic Cystitis in Rats through the Inhibition of Oxidative Damage, MAPKs, and NF-κB Pathways

This study investigated the possible effects and molecular mechanisms of diallyl disulfide (DADS) against cyclophosphamide (CP)-induced hemorrhagic cystitis (HC) in rats. Inflammation response was assessed by histopathology and serum cytokines levels. We determined the protein expressions of nuclear transcription factor kappa-B (NF-κB), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and tumor necrosis factor-α (TNF-α), oxidative stress, urinary nitrite-nitrate, malondialdehyde (MDA), and 8-hydroxy-2’-deoxyguanosine (8-OHdG). Finally, we studied the involvement of mitogen-activated protein kinases (MAPKs) signaling in the protective effects of DADS against CP-induced HC. CP treatment caused a HC which was evidenced by an increase in histopathological changes, proinflammatory cytokines levels, urinary nitrite-nitrate level, and the protein expression of NF-κB, COX-2, iNOS, TNF-α, p-c-Jun N-terminal kinase (JNK), and p-extracellular signal regulated kinase (ERK). The significant decreases in glutathione content and glutathione-S-transferase and glutathione reductase activities, and the significant increase in MDA content and urinary MDA and 8-OHdG levels indicated that CP-induced bladder injury was mediated through oxidative DNA damage. In contrast, DADS pretreatment attenuated CP-induced HC, including histopathological lesion, serum cytokines levels, oxidative damage, and urinary oxidative DNA damage. DADS also caused significantly decreased the protein expressions of NF-κB, COX-2, iNOS, TNF-α, p-JNK, and p-ERK. These results indicate that DADS prevents CP-induced HC and that the protective effects of DADS may be due to its ability to regulate proinflammatory cytokines production by inhibition of NF-κB and MAPKs expressions, and its potent anti-oxidative capability through reduction of oxidative DNA damage in the bladder.

Protective effects of lipoic acid and mesna on cyclophosphamide-induced haemorrhagic cystitis in mice

The protective roles of lipoic acid (LA)/vitamin C (VC) and mesna on preventing cyclophosphamide (CYP)-induced haemorrhagic cystitis (HC) were investigated. Swiss mice were divided into five groups randomly. HC was induced by a single dose of CYP injection (150-mg kg(-1) bodyweight). Group I was injected with saline (four times in total) throughout as control group. Group II received CYP and three equal doses of saline. Group III received CYP and three doses of mesna, whereas Group IV (or Group V) received CYP, mesna + two doses of VC (or LA). All injections were performed intraperitoneally. After 24 h of cystitis induction, the bladders were collected for all the experiments. Histological characterization showed that CYP injection resulted in severe HC. Reactive oxygen species (ROS) and thiobarbituric acid reactive substances' levels were increased in CYP group. The activities of antioxidant enzymes, e.g. superoxide dismutase, catalase, glutathione S-transferase and glutathione peroxidase, were inhibited significantly in CYP groups, respectively. In addition, activation of c-jun N-terminal kinases (JNK) and p38 mitogen-activated protein kinase (MAPK) may be involved in the mechanism of CYP-induced HC but not extracellular signal regulated kinases (ERK). Significant suppression of p38 phosphorylation on Group V suggests that LA and mesna may have synergistic beneficial effect. In Groups III-V, all the parameters of HC and oxidative stress were inhibited significantly. Taking together, we found that these results illustrated that ROS play an important role on CYP-induced HC and the administration of LA/VC with mesna may have therapeutic potential against CYP-induced bladder HC.

Regulation of NF-κB-induced inflammatory signaling by lipid peroxidation-derived aldehydes

Oxidative stress plays a critical role in the pathophysiology of a wide range of diseases including cancer. This view has broadened significantly with the recent discoveries that reactive oxygen species initiated lipid peroxidation leads to the formation of potentially toxic lipid aldehyde species such as 4-hydroxy-trans-2-nonenal (HNE), acrolein, and malondialdehyde which activate various signaling intermediates that regulate cellular activity and dysfunction via a process called redox signaling. The lipid aldehyde species formed during synchronized enzymatic pathways result in the posttranslational modification of proteins and DNA leading to cytotoxicity and genotoxicty. Among the lipid aldehyde species, HNE has been widely accepted as a most toxic and abundant lipid aldehyde generated during lipid peroxidation. HNE and its glutathione conjugates have been shown to regulate redox-sensitive transcription factors such as NF-κB and AP-1 via signaling through various protein kinase cascades. Activation of redox-sensitive transcription factors and their nuclear localization leads to transcriptional induction of several genes responsible for cell survival, differentiation, and death. In this review, we describe the mechanisms by which the lipid aldehydes transduce activation of NF-κB signaling pathways that may help to develop therapeutic strategies for the prevention of a number of inflammatory diseases.

Acrolein-induced activation of mitogen-activated protein kinase signaling is mediated by alkylation of thioredoxin reductase and thioredoxin 1

Cigarette smoking remains a major health concern worldwide, and many of the adverse effects of cigarette smoke (CS) can be attributed to its abundant electrophilic aldehydes, such as acrolein (2-propenal). Previous studies indicate that acrolein readily reacts with thioredoxin reductase 1 (TrxR1), a critical enzyme involved in regulation of thioredoxin (Trx)-mediated redox signaling, by alkylation at its selenocysteine (Sec) residue. Because alkylation of Sec within TrxR1 has significant implications for its enzymatic function, we explored the potential importance of TrxR1 alkylation in acrolein-induced activation or injury of bronchial epithelial cells. Exposure of human bronchial epithelial HBE1 cells to acrolein (1–30 μM) resulted in dose-dependent loss of TrxR thioredoxin reductase activity, which coincided with its alkylation, as determined by biotin hydrazide labeling, and was independent of initial GSH status. To test the involvement of TrxR1 in acrolein responses in HBE1 cells, we suppressed TrxR1 using siRNA silencing or augmented TrxR1 by cell supplementation with sodium selenite. Acrolein exposure of HBE1 cells induced dose-dependent activation of the MAP kinases, extracellular regulated1 kinase (ERK), c-Jun N-terminal kinase (JNK), and p38, and activation of JNK was markedly enhanced after selenite-mediated induction of TrxR1, and was associated with increased alkylation of TrxR1. Conversely, siRNA silencing of TrxR1 significantly suppressed the ability of acrolein to activate JNK, and also appeared to attenuate acrolein-dependent activation of ERK and p38. Alteration of initial TrxR1 levels by siRNA or selenite supplementation also affected initial Trx1 redox status and acrolein-mediated alkylation of Trx1, but did not significantly affect acrolein-mediated activation of HO-1 or cytotoxicity. Collectively, our findings indicate that alkylation of TrxR1 and/or Trx1 may contribute directly to acrolein-mediated activation of MAP kinases such as JNK, and may therefore be important in acrolein-induced alterations in airway epithelial function, as a contributing mechanism in tobacco-related respiratory disease.

Enhancement of auranofin-induced apoptosis in MCF-7 human breast cells by selenocystine, a synergistic inhibitor of thioredoxin reductase

Thioredoxin system plays an important role in regulation of intracellular redox balance and various signaling pathways. Thioredoxin reductase (TrxR) is overexpressed in many cancer cells and has been identified as a potential target of anticancer drugs. Auranofin (AF) is potent TrxR inhibitor with novel in vitro and in vivo anticancer activities. Selenocystine (SeC) is a nutritionally available selenoamino acid with selective anticancer effects through induction of apoptosis. In the present study, we demonstrated the synergistic effects and the underlying molecular mechanisms of SeC in combination with AF on MCF-7 human breast cancer cells. The results showed that SeC and AF synergistically inhibited the cancer cell growth through induction of ROS-dependent apoptosis with the involvement of mitochondrial dysfunction. DNA damage-mediated p53 phosphorylation and down-regulation of phosphorylated AKT and ERK also contributed to cell apoptosis. Moreover, we demonstrated the important role of TrxR activity in the synergistic action of SeC and AF. Taken together, our results suggest the strategy to use SeC and AF in combination could be a highly efficient way to achieve anticancer synergism by targeting TrxR.

Protective effects of caffeic acid and caffeic acid phenethyl ester against acrolein-induced neurotoxicity in HT22 mouse hippocampal cells

Acrolein-induced oxidative stress is hypothesized to involve in the etiology of Alzheimer's disease (AD). Caffeic acid (CA) and caffeic acid phenethyl ester (CAPE) have antioxidative and neuroprotective properties. The present study investigated the protective effects of CA/CAPE on acrolein-induced oxidative neuronal toxicity. HT22 mouse hippocampal cells were pretreated with CA/CAPE and then exposed to acrolein. Cell viability, intracellular reactive oxygen species (ROS), and glutathione (GSH) level were measured. MAPKs and Akt/GSK3β signaling proteins as well as α/β-secretase of amyloid protein precursor were assayed by Western blotting. Pretreatment with CA/CAPE significantly attenuated acrolein-induced neurotoxicity, ROS accumulation, and GSH depletion. Further study suggested that CA/CAPE showed protective effects against acrolein by modulating MAPKs and Akt/GSK3β signaling pathways. Moreover, CA/CAPE restored the changes of β-secretase (BACE-1) and/or activation of α-secretase (ADAM-10) induced by acrolein. These findings suggest that CA/CAPE may provide a promising approach for the treatment of acrolein-related neurodegenerative diseases, such as AD.

The effects of acrolein on the thioredoxin system: implications for redox-sensitive signaling

The reactive aldehyde acrolein is a ubiquitous environmental pollutant and is also generated endogenously. It is a strong electrophile and reacts rapidly with nucleophiles including thiolates. This review focuses on the effects of acrolein on thioredoxin reductase (TrxR) and thioredoxin (Trx), which are major regulators of intracellular protein thiol redox balance. Acrolein causes irreversible effects on TrxR and Trx, which are consistent with the formation of covalent adducts to selenocysteine and cysteine residues that are key to their activity. TrxR and Trx are more sensitive than some other redox-sensitive proteins, and their prolonged inhibition could disrupt a number of redox-sensitive functions in cells. Among these effects are the oxidation of peroxiredoxins and the activation of apoptosis signal regulating kinase (ASK1). ASK1 promotes MAP kinase activation, and p38 activation contributes to apoptosis and a number of other acrolein-induced stress responses. Overall, the disruption of the TrxR/Trx system by acrolein could be significant early and prolonged events that affect many aspects of redox-sensitive signaling and oxidant stress.

Specific PKC isoforms regulate LPS-stimulated iNOS induction in murine microglial cells

Background

Excessive production of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) in reactive microglia is a major contributor to initiation/exacerbation of inflammatory and degenerative neurological diseases. Previous studies have indicated that activation of protein kinase C (PKC) can lead to iNOS induction. Because of the existence of various PKC isoforms and the ambiguous specificity of PKC inhibitors, it is unclear whether all PKC isoforms or a specific subset are involved in the expression of iNOS by reactive microglia. In this study, we employed molecular approaches to characterize the role of each specific PKC isoform in the regulation of iNOS expression in murine microglia.

Methods

Induction of iNOS in response to bacterial endotoxin lipopolysaccharide (LPS) was measured in BV-2 murine microglia treated with class-specific PKC inhibitors, or transfected with siRNA to silence specific PKC isoforms. iNOS expression and MAPK phosphorylation were evaluated by western blot. The role of NF-κB in activated microglia was examined by determining NF-κB transcriptional response element- (TRE-) driven, promoter-mediated luciferase activity.

Results

Murine microglia expressed high levels of nPKCs, and expressed relatively low levels of cPKCs and aPKCs. All PKC inhibitors attenuated induction of iNOS in LPS-activated microglia. Knockdown of PKC δ and PKC β attenuated ERK1/2 and p38 phosphorylation, respectively, and blocked NF-κB activation that leads to the expression of iNOS in reactive microglia.

Conclusions

Our results identify PKC δ and β as the major PKC isoforms regulating iNOS expression in reactive microglia. The signaling pathways mediated by PKC involve phosphorylation of distinct MAPKs and activation of NF-κB. These results may help in the design of novel and selective PKC inhibitors for the treatment of many inflammatory and neurological diseases in which production of NO plays a pathogenic role.

Mutagenicity of acrolein and acrolein-induced DNA adducts

Acrolein mutagenicity relies on DNA adduct formation. Reaction of acrolein with deoxyguanosine generates alpha-hydroxy-1, N(2)-propano-2'-deoxyguanosine (alpha-HOPdG) and gamma-hydroxy-1, N(2)-propano-2'-deoxyguanosine (gamma-HOPdG) adducts. These two DNA adducts behave differently in mutagenicity. gamma-HOPdG is the major DNA adduct and it can lead to interstrand DNA-DNA and DNA-peptide/protein cross-links, which may induce strong mutagenicity; however, gamma-HOPdG can be repaired by some DNA polymerases complex and lessen its mutagenic effects. alpha-HOPdG is formed much less than gamma-HOPdG, but difficult to be repaired, which contributes to accumulation in vivo. Results of acrolein mutagenicity studies haven't been confirmed, which is mainly due to the conflicting mutagenicity data of the major acrolein adduct (gamma-HOPdG). The minor alpha-HOPdG is mutagenic in both in vitro and in vivo test systems. The role of alpha-HOPdG in acrolein mutagenicity needs further investigation. The inconsistent result of acrolein mutagenicity can be attributed, at least partially, to a variety of acrolein-DNA adducts formation and their repair in diverse detection systems. Recent results of detection of acrolein-DNA adduct in human lung tissues and analysis of P53 mutation spectra in acrolein-treated cells may shed some light on mechanisms of acrolein mutagenicity. These aspects are covered in this mini review.

Acrolein induces apoptosis through the death receptor pathway in A549 lung cells: role of p53This review is one of a selection of papers published in a Special Issue on Oxidative Stress in Health and Disease

Acrolein, a highly reactive α,β-unsaturated aldehyde, is an omnipresent environmental pollutant. Chronic and acute human exposures occur through exogenous and endogenous sources, including food, vapors of overheated cooking oil, house and forest fires, cigarette smoke, and automobile exhaust. Acrolein is a toxic byproduct of lipid peroxidation, which has been implicated in pulmonary, cardiac, and neurodegenerative diseases. This study shows that p53 is an initiating factor in acrolein-induced death receptor activation during apoptosis in A549 human lung cells. Exposure of cells to acrolein (0–50 µmol/L) mainly caused apoptosis, which was manifested by execution phase events such as condensation of nuclear chromatin, phosphatidylserine externalization, and poly(ADP-ribose) polymerase (PARP) cleavage. Levels of necrosis (~5%) were low. Acrolein triggered the death receptor pathway of apoptosis, causing elevation of Fas ligand (FasL) and translocation of adaptor protein Fas-associated death domain to the plasma membrane. Acrolein caused activation of caspase-8, caspase-2, caspase-7, and the cross-talk pathway mediated by Bid cleavage. Activation of p53 and increased expression of p53-upregulated modulator of apoptosis (PUMA) occurred in response to acrolein. FasL upregulation and caspase-8 activation were decreased by p53 inhibitor pifithrin-α and antioxidant polyethylene glycol catalase. These findings increase our knowledge about the induction of cell death pathways by acrolein, which has important implications for human health.

The ERK and PI3K signaling pathways mediate inhibition of insulin-like growth factor-1 receptor mRNA expression by somatostatin

Somatostatins (SSs) are a structurally diverse family of peptide hormones that regulate various aspects of growth, development, and metabolism in vertebrates. Previously, we showed that SSs inhibit mRNA and functional expression of insulin-like growth factor-1 receptors (IGFR1) in gill filaments of rainbow trout. In this study, we used trout gill filaments, which express in high abundance two distinct IGFR1s, IGFR1A and IGFR1B, to examine the mechanism(s) through which SSs exert their inhibitory effects on IGFR1 expression. SS-14, a predominat SS isoform, directly stimulated the phosphorylation of extracellular signal-regulated kinase (ERK) and protein kinase B (Akt), a downstream target of phosphatidylinositol 3-kinase (PI3K), in filaments incubated in vitro. Activation of ERK and Akt by SS-14 was rapid, occuring within 5-10 min, and was concentration-dependent. The ERK pathway inhibitor, U0126, retarded SS-14-stimulated phosphorylation of ERK 1/2, whereas the PI3K inhibitor, LY294002, blocked SS-14-stimulated phosphorylation of Akt. SS-14-inhibited expression of IGFR1 mRNAs was blocked by both U0126 and LY294002. These data indicate that SS-14 inhibition of IGFR1 mRNA expression is mediated through the ERK and PI3K/Akt signaling pathways.

The role of polyamine metabolism in neuronal injury following cerebral ischemia

Stroke is a leading cause of morbidity and mortality in the US, with secondary damage following the initial insult contributing significantly to overall poor outcome. Prior investigations have shown that the metabolism of certain polyamines such as spermine, spermidine, and putrescine are elevated in ischemic parenchyma, resulting in an increase in their metabolite concentration. Polyamine metabolites tend to be cytotoxic, leading to neuronal injury in the penumbra following stroke and expansion of the area of infarcted tissue. Although the precise mechanism is unclear, the presence of reactive aldehydes produced through polyamine metabolism, such as 3-aminopropanal and acrolein, have been shown to correlate with the incidence of cerebral vasospasm, disruption of oxidative metabolism and mitochondrial functioning, and disturbance of cellular calcium ion channels. Regulation of the polyamine metabolic pathway, therefore, may have the potential to limit injury following cerebral ischemia. To this end, we review this pathway in detail with an emphasis on clinical applicability.

Apoptogenic effect of 7,8-diacetoxy-4-methylcoumarin and 7,8-diacetoxy-4-methylthiocoumarin in human lung adenocarcinoma cell line: role of NF-kappaB, Akt, ROS and MAP kinase pathway

Coumarin (1,2-benzopyrone) is a naturally occurring fragrant compound found in a variety of plants and spices. Coumarins have attracted intense interest in recent years because of their diverse pharmacological activities. This study examines the antioxidant coumarin 7,8-diacetoxy-4-methylcoumarin (DAMC) and its thiocoumarin derivative 7,8-diacetoxy-4-methylthiocoumarin (DAMTC) for their effect on human non-small cell lung cancer A549 cells. Here we show that both DAMC and DAMTC not only inhibited cell proliferation, but also induced apoptosis with an IC(50) of 160 microg/ml as confirmed by morphological examination, annexin-V assay and flow cytometric analysis. Interestingly, it was observed that these two coumarin compounds exhibited little cytotoxicity towards peripheral blood mononuclear cells but induced apoptosis in malignant cells. DAMC/DAMTC treatment also resulted in pronounced release of apoptogenic cytochrome c from mitochondria to cytosol, alteration of mitochondrial membrane potential (DeltaPsi(m)), and activation of caspase-9 and caspase-3. Although an increase in the levels of reactive oxygen species (ROS) was observed, pre-treatment with antioxidant showed no protective effect against DAMC/DAMTC-induced apoptosis. Results of present study suggest that downregulation of Bcl-xl, Cox-2 and mitogen activated protein kinase pathway and upregulation of p53, Akt and NF-kappaB pathway are involved in the underlying molecular mechanism of apoptosis induction by DAMC and DAMTC in A549 cells.

Intracellular redox status and oxidative stress: implications for cell proliferation, apoptosis, and carcinogenesis

Oxidative stress can be defined as the imbalance between cellular oxidant species production and antioxidant capability. Reactive oxygen species (ROS) are involved in a variety of different cellular processes ranging from apoptosis and necrosis to cell proliferation and carcinogenesis. In fact, molecular events, such as induction of cell proliferation, decreased apoptosis, and oxidative DNA damage have been proposed to be critically involved in carcinogenesis. Carcinogenicity and aging are characterized by a set of complex endpoints, which appear as a series of molecular reactions. ROS can modify many intracellular signaling pathways including protein phosphatases, protein kinases, and transcription factors, suggesting that the majority of the effects of ROS are through their actions on signaling pathways rather than via non-specific damage of macromolecules; however, exact mechanisms by which redox status induces cells to proliferate or to die, and how oxidative stress can lead to processes evoking tumor formation are still under investigation.

Apoptosis induced by capsaicin in prostate PC-3 cells involves ceramide accumulation, neutral sphingomyelinase, and JNK activation

Numerous studies have recently focused on the anticarcinogenic, antimutagenic, or chemopreventive activities of the main pungent component of red pepper, capsaicin (N-vanillyl-8-methyl-1-nonenamide). We have previously shown that, in the androgen-independent prostate cancer PC-3 cells, capsaicin inhibits cell growth and induces apoptosis through reactive oxygen species (ROS) generation [Apoptosis 11 (2006) 89-99]. In the present study, we investigated the signaling pathways involved in the antiproliferative effect of capsaicin. Here, we report that capsaicin apoptotic effect was mediated by ceramide generation which occurred by sphingomyelin hydrolysis. Using siRNA, we demonstrated that N-SMase expression is required for the effect of capsaicin on prostate cell viability. We then investigated the role of MAP kinase cascades, extracellular signal-regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 MAPK, in the antiproliferative effect of capsaicin, and we confirmed that capsaicin could activate ERK and JNK but not p38 MAPK. Pharmacological inhibition of JNK kinase, as well as inhibition of ROS by the reducing agent N-acetylcysteine, prevented ceramide accumulation and capsaicin-induced cell death. However, inhibition of ceramide accumulation by the SMase inhibitor D609 did not modify JNK activation. These data reveal JNK as an upstream regulator of ceramide production. Capsaicin-promoted activation of ERK was prevented with all the inhibitors tested. We conclude that capsaicin induces apoptosis in PC-3 cells via ROS generation, JNK activation, ceramide accumulation, and second, ERK activation.

Characterization of chlorpyrifos-induced apoptosis in placental cells

The mechanism by which chlorpyrifos exerts its toxicity in fetal and perinatal animals has yet to be elucidated. Since the placenta is responsible for transport of nutrients and is a major supplier hormone to the fetus, exposure to xenobiotics that alter the function or viability of placenta cells could ostensibly alter the development of the fetus. In this study, JAR cells were used to determine if CPF and the metabolites 3,5,6-trichloro-2-pyridinol (TCP) and chlorpyrifos-oxon (CPO) are toxic to the placenta. Our results indicate that chlorpyrifos (CPF), and its metabolite chlorpyrifos-oxon (CPO) caused a dose-dependent reduction in cellular viability with CPF being more toxic than its metabolites. Chlorpyrifos-induced toxicity was characterized by the loss of mitochondrial potential, the appearance of nuclear condensation and fragmentation, down-regulation of Bcl-2 as well as up-regulation of TNFalpha and FAS mRNA. Pharmacological inhibition of FAS, nicotinic and TNF-alpha receptors did not attenuate CPF-induced toxicity. Atropine exhibited minimal ability to reverse toxicity. Furthermore, signal transduction inhibitors PD98059, SP600125, LY294002 and U0126 failed to attenuate toxicity; however, SB202190 (inhibitor of p38alpha and p38beta MAPK) sensitized cells to CPF-induced toxicity. Pan-caspase inhibitor Q-VD-OPh produced a slight but significant reversal of CPF-induced toxicity indicating that the major caspase pathways are not integral to CPF-induced toxicity. Taken collectively, these results suggest that chlorpyrifos induces apoptosis in placental cells through pathways not dependent on FAS/TNF signaling, activation of caspases or inhibition of cholinesterase. In addition, our data further indicates that activation of p38 MAPK is integral to the protection cells against CPF-induced injury.

Characterization of acrolein-glycerophosphoethanolamine lipid adducts using electrospray mass spectrometry

Acrolein is a toxic, highly reactive alpha,beta-unsaturated aldehyde. In the current study, the products of acrolein after reaction with glycerophosphoethanolamine (GPEtn) lipids have been characterized using electrospray tandem mass spectrometry. The major product formed involves the addition of two acrolein molecules to the primary amine of GPEtn lipids and subsequent aldol condensation to form 1,2-diradyl- sn-glycero-3-phosphoethanol-(3-formyl-4-hydroxy)piperidine (FHP) lipids. Upon sodium borohydride reduction, 1,2-diradyl- sn-glycero-3-phosphoethanol-(3-hydroxymethyl-4-hydroxy)piperidine (HMHP) lipids and 1,2-diradyl- sn-glycero-3-phosphoethanol-(3-hydroxymethyl-3,4-dehydro)piperidine (HMDP) lipids were selectively detected using electrospray tandem mass spectrometry by employing precursors of m/ z 256.1 and 238.1 scans, respectively. HMHP lipid and HMDP lipid molecular species were detected upon treatment of HL-60 cells with concentrations of acrolein as low as 10 microM. While the biological implications of these acrolein GPEtn adducts have yet to be established, these structural characterization studies reported herein reveal the facile formation of acrolein GPEtn lipid adducts in vitro, which could influence subsequent biochemical events within the cell.