Acrylamide induces mitochondrial dysfunction and apoptosis in BV-2 microglial cells

Protective effects of a Ganoderma atrum polysaccharide against acrylamide induced oxidative damage via a mitochondria mediated intrinsic apoptotic pathway in IEC-6 cells

The preventive role of a purified Ganoderma atrum polysaccharide PSG-1-F₂ as a new dietary antioxidant against the intestinal toxicity of acrylamide (ACR) was investigated in vitro. Our results showed that ACR could induce oxidative stress in IEC-6 cells by the overproduction of reactive oxygen species (ROS) and malondialdehyde (MDA), and as well as the reduction in the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). In addition, the induction of a mitochondria-mediated intrinsic apoptotic pathway by ACR was evidenced by the events of loss of mitochondrial membrane potential, bax/bcl-2 dysregulation, cytochrome c release, and activation of caspase-3. Interestingly, PSG-1-F₂ was able to suppress ACR toxicity by improving the redox status of IEC-6 cells and by attenuating mitochondria-mediated apoptosis. Its protective effect was even superior to the clinically used antioxidant N-acetylcysteine (NAC). This study uniquely introduces PSG-1-F₂ as a potential inhibitor of ACR-induced stress and toxicities.

Acrylamide exerts its cytotoxicity in NIH/3T3 fibroblast cells by apoptosis

OBJECTIVE

Acrylamide is a chemical utilized in various industries, and many studies have demonstrated its toxicity. The NIH/3T3 mouse embryonic cell line is the standard cell line of fibroblasts, which have a pivotal role with their versatile functions in the body. However, only two studies have attempted to investigate the effect of acrylamide on these crucial cells. To fill this knowledge gap, we aimed to determine the effects of acrylamide on NIH/3T3 cells.

METHOD

First, we performed the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay and calculated the IC₅₀ dose of acrylamide. Then, we treated cells with the IC₅₀ dose of acrylamide for 24 h and determined whether the dominant death mode of NIH/3T3 cells was apoptosis or necrosis by annexin V and caspase 3/7 assays. Finally, we performed confocal microscopy and transmission electron microscope (TEM) analysis for observing the morphological alterations.

RESULTS

MTT assay results showed that acrylamide treatment reduced the viability of NIH/3T3 cells dose-dependently and that the IC₅₀ of acrylamide was 6.73 mM. Based on annexin V and caspase 3/7 assays, the dominant death mode of NIH/3T3 cells was determined to be apoptosis. Also, caspase 3/7 activities of the acrylamide-treated NIH/3T3 cells were three times greater than those of the untreated NIH/3T3 cells. Furthermore, we observed membrane blebbing, nuclear chromatin clumping, and cytoplasmic vacuolization in TEM analysis and apparent apoptotic bodies, nuclear fragmentations, and condensations in confocal microscopy.

CONCLUSIONS

In conclusion, our results suggested that the IC₅₀ of acrylamide against NIH/3T3 cells for 24 h was 6.73 mM and that acrylamide exerted its cytotoxic and anti-proliferative effects on these cells mainly via apoptosis.

Protective effects of lipoic acid against acrylamide-induced neurotoxicity: involvement of mitochondrial energy metabolism and autophagy

Acrylamide (ACR) is a chronic neurotoxin that is generated in high-starch foods during heat processing. Alpha-lipoic acid (LA) is an antioxidant that occurs in most plants and animals. The objective of this study was to reveal the mechanism of ACR-triggered neurotoxicity and identify the protective role of LA in SH-SY5Y cells. In this study, LA restored ACR-stimulated depletion of glutathione content and mitochondrial membrane potential, moderated the activation of inflammatory pathways, and recovered the Keap1/Nrf2 pathway. Moreover, LA upregulated the activities of oxidative phosphorylation complexes and diminished ACR-induced variation in AMPK/GSK3β, Ca²⁺ disturbance, and ATP depletion. The Sirt1/PGC-1α pathway was inhibited by ACR. Notably, autophagy was activated in the mitochondria-mediated apoptosis induced by ACR, which was also blocked by LA. Overall, our study demonstrated the pivotal roles of the mitochondrial energy metabolism and autophagy in the protective effects of LA and cytotoxicity of ACR in SH-SY5Y cells.

Nobiletin protects against insulin resistance and disorders of lipid metabolism by reprogramming of circadian clock in hepatocytes

SCOPE

Circadian clock plays a principal role in orchestrating our daily physiology and metabolism, and their perturbation can evoke metabolic diseases such as fatty liver and insulin resistance. Nobiletin (NOB) has been demonstrated to possess antitumor and neuroprotective activities. The objective of the current study is to determine potential effects of NOB on modulating the core clock gene Bmal1 regarding ameliorating glucolipid metabolic disorders.

RESULTS

Our results revealed that NOB partially reverse the relatively shallow daily oscillations of circadian clock genes and reset phase-shifting circadian rhythms in primary hepatocytes under metabolic disorders conditions. Importantly, NOB was found to be effective at amplifying glucose uptake via stimulating IRS-1/AKT signaling pathway, as well as blunting palmitate-induced lipogenesis in HepG2 cells via modulating AMPK-Sirt1 signaling pathway and key enzymes of de novo lipogenesis in a Bmal1-dependent manner. NOB attenuated palmitate-stimulated excessive secretions of ROS, restored the depletions of mitochondrial membrane potential, which is similar to the recovery in expressions of mitochondrial respiration complex I-IV.

CONCLUSION

This study is the first to provide compelling evidences that NOB prevent cellular glucolipid metabolic imbalance and mitochondrial function in a Bmal1-dependent manner. Overall, NOB may serve as a nutritional preventive strategy in recovering metabolic disorders relevant to circadian clock.

Learning, memory deficits, and impaired neuronal maturation attributed to acrylamide

Acrylamide (ACR) is a neurotoxin known to produce neurotoxicity characterized by ataxia, skeletal muscle weakness, cognitive impairment, and numbness of the extremities. Previously, investigators reported that high-dose (50 mg/kg) ACR impaired hippocampal neurogenesis and increased neural progenitor cell death; however, the influence of subchronic environmentally relevant low dose-(2, 20, or 200 μg/kg) ACRs have not been examined in adult neurogenesis or cognitive function in mice. Accordingly, the aim of the present study was to investigate whether low-dose ACR adversely affected mouse hippocampal neurogenesis and neurocognitive functions. Male C57BL/6 mice were orally administered vehicle or ACR at 2, 20, or 200 μg/kg/day for 4 weeks. ACR did not significantly alter the number of newly generated cells or produce neuroinflammation or neuronal loss in hippocampi. However, behavioral studies revealed that 200 μg/kg ACR produced learning and memory impairment. Furthermore, incubation of ACR with primary cultured neurons during the developmental stage was found to delay neuronal maturation without affecting cell viability indicating the presence of developmental neurotoxicity. These findings indicate that although exposure to in vivo low-dose ACR daily for 4 weeks exerted no apparent marked effect on hippocampal neurogenesis, in vitro observations in primary cultured neurons noted adverse effects on learning and memory impairment suggestive of neurotoxic actions.

Tea polyphenols ameliorates neural redox imbalance and mitochondrial dysfunction via mechanisms linking the key circadian regular Bmal1

Circadian rhythms are autonomous anticipatory oscillators that control a large array of physiological and metabolic processes. Compelling evidence points toward an interplay between circadian rhythms and cellular redox metabolism. Dysregulation of circadian rhythms is associated with neurodegenerative diseases and accelerated aging. Tea polyphenols (TP) is one of the most used antioxidants and exerts beneficial effect on neurodegenerative diseases. The aim of this study is to investigate whether circadian clock mechanisms are involved in the protection effect of TP against neural redox imbalance and mitochondrial dysfunction in SH-SY5Y cells. In the current study, our results revealed that TP, as a Bmal1-enhancing natural compound, can reverse the relatively shallow daily oscillations of circadian clock genes transcription and protein expression in SH-SY5Y neuronal cells under oxidative stress conditions. Furthermore, TP pretreatment significantly ameliorated H2O2-elicited mitochondria impairment via manipulating mitochondrial dynamics and mitochondrial membrane potential, which is consistent with the recovery in expression of mitochondrial respiration complex I-IV in Bmal1-dependent efficiency. Furthermore, Bmal1 is involved in TP-stimulated Nrf2/ARE/HO-1 and AKT/CREB/BDNF signaling pathway. Hence, TP may serve as a nutritional preventive strategy in the recovery of oxidative stress-related neurodegenerative disease via modulating circadian clock.

Induction of Cell Death by Betulinic Acid through Induction of Apoptosis and Inhibition of Autophagic Flux in Microglia BV-2 Cells

Betulinic acid (BA), a natural pentacyclic triterpene found in many medicinal plants is known to have various biological activity including tumor suppression and anti-inflammatory effects. In this study, the cell-death induction effect of BA was investigated in BV-2 microglia cells. BA was cytotoxic to BV-2 cells with IC₅₀ of approximately 2.0 μM. Treatment of BA resulted in a dose-dependent chromosomal DNA degradation, suggesting that these cells underwent apoptosis. Flow cytometric analysis further confirmed that BA-treated BV-2 cells showed hypodiploid DNA content. BA treatment triggered apoptosis by decreasing Bcl-2 levels, activation of capase-3 protease and cleavage of PARP. In addition, BA treatment induced the accumulation of p62 and the increase in conversion of LC3-I to LC3-II, which are important autophagic flux monitoring markers. The increase in LC3-II indicates that BA treatment induced autophagosome formation, however, accumulation of p62 represents that the downstream autophagy pathway is blocked. It is demonstrated that BA induced cell death of BV-2 cells by inducing apoptosis and inhibiting autophagic flux. These data may provide important new information towards understanding the mechanisms by which BA induce cell death in microglia BV-2 cells.

Acrylamide-induced neurotoxicity in primary astrocytes and microglia: Roles of the Nrf2-ARE and NF-κB pathways

Acrylamide (AA) is a common food contaminant formed during food heat processing that has neurotoxic effects. We hypothesize that AA induces oxidative stress in astrocytes and microglia, leading to neurotoxicity. Oxidative status, translocation of Nrf2 and NF-κB, and related down-stream targets were measured in primary astrocytes and microglia obtained from BALB/c mice. The results showed that AA increased reactive oxygen species (ROS) formation and reduced glutathione levels, causing successive events associated with oxidative stress, including 4-hydroxynonenal and 8-hydroxy-2-deoxyguanosine adduct formation, in both cell types. Both Nrf2 and NF-κB pathways were activated, but Nrf2 and its downstream antioxidative genes acted at earlier stages in both cell types before NF-κB activation. After NF-κB activation, related cytokines, including IL-6, TNF-α, G-CSF, and IL-1β, were released and cell viability decreased. Greater ROS generation, faster glutathione reduction, and increased oxidative adduct formation were observed in microglia compared with astrocytes. Moreover, Nrf2/NF-κB and its downstream genes were up-regulated much faster and to greater degrees in microglia than astrocytes. These results clarify the roles of the Nrf2 and NF-κB pathways in AA-induced neurotoxicity. These cellular responses may provide new insights for the development of adverse outcome pathway approaches for risk assessments of AA.

Sesamol Induces Human Hepatocellular Carcinoma Cells Apoptosis by Impairing Mitochondrial Function and Suppressing Autophagy

Sesamol, a nutritional phenolic antioxidant compound enriched in sesame seeds, has been shown to have potential anticancer activities. This study aims at characterizing the antitumor efficacy of sesamol and unveiling the importance of mitochondria in sesamol-induced effects using a human hepatocellular carcinoma cell line, HepG2 cells. Results of this study showed that sesamol treatment suppressed colony formation, elicited S phase arrest during cell cycle progression, and induced both intrinsic and extrinsic apoptotic pathway in vitro with a dose-dependent manner. Furthermore, sesamol treatment elicited mitochondrial dysfunction by inducing a loss of mitochondrial membrane potential. Impaired mitochondria and accumulated H2O2 production resulted in disturbance of redox-sensitive signaling including Akt and MAPKs pathways. Mitochondrial biogenesis was inhibited as suggested by the decline in expression of mitochondrial complex I subunit ND1, and the upstream AMPK/PGC1α signals. Importantly, sesamol inhibited mitophagy and autophagy through impeding the PI3K Class III/Belin-1 pathway. Autophagy stimulator rapamycin reversed sesamol-induced apoptosis and mitochondrial respiration disorders. Moreover, it was also shown that sesamol has potent anti-hepatoma activity in a xenograft nude mice model. These data suggest that mitochondria play an essential role in sesamol-induced HepG2 cells death, and further research targeting mitochondria will provide more chemotherapeutic opportunities.

Impact of Acrylamide on Calcium Signaling and Cytoskeletal Filaments in Testes From F344 Rat

Acrylamide (AA) at high exposure levels is neurotoxic, induces testicular toxicity, and increases dominant lethal mutations in rats. RNA-sequencing in testes was used to identify differentially expressed genes (DEG), explore AA-induced pathway perturbations that could contribute to AA-induced testicular toxicity and then used to derive a benchmark dose (BMD). Male F344/DuCrl rats were administered 0.0, 0.5, 1.5, 3.0, 6.0, or 12.0 mg AA/kg bw/d in drinking water for 5, 15, or 31 days. The experimental design used exposure levels that spanned and exceeded the exposure levels used in the rat dominant lethal, 2-generation reproductive toxicology, and cancer bioassays. The time of sample collection was based on previous studies that developed gene expression-based BMD. At 12.0 mg/kg, there were 38, 33, and 65 DEG ( P value <.005; fold change >1.5) in the testes after 5, 15, or 31 days of exposure, respectively. At 31 days, there was a dose-dependent increase in the number of DEG, and at 12.0 mg/kg/d the top three functional clusters affected by AA exposure were actin filament organization, response to calcium ion, and regulation of cell proliferation. The BMD lower 95% confidence limit using DEG ranged from 1.8 to 6.8 mg/kg compared to a no-observed-adverse-effect-level of 2.0 mg/kg/d for male reproductive toxicity. These results are consistent with the known effects of AA on calcium signaling and cytoskeletal actin filaments leading to neurotoxicity and suggest that AA can cause rat dominant lethal mutations by these same mechanisms leading to impaired chromosome segregation during cell division.

Metabolomics analysis of serum from subjects after occupational exposure to acrylamide using UPLC-MS

Since occupational exposure to acrylamide (ACR) may cause nerve damage, sensitive biomarkers to evaluate the early effects of ACR on human health are needed. In the present study, we have compared a group of individuals with occupational exposure to ACR (contact group, n = 65) with a group of individuals with no exposure (non-contact group, n = 60). Serum metabolomics analysis of the contact and non-contact groups was carried out using ultra performance liquid chromatograph/time of flight mass spectrometry, combined with multivariate analysis, to identify potential metabolites. Serum biochemical indexes of the contact and non-contact groups were also determined using an automatic biochemistry analyzer. There was a clear separation between the contact group and the non-contact group; receiver operator characteristic curve analysis suggested that phytosphingosine, 4E,15Z-bilirubin IXa and tryptophan were the best metabolites to use as biomarkers. Liver function was also found to be abnormal in the contact group. Important, ACR-related, metabolic changes were seen in the contact group and new biomarkers for assessing the toxicity of ACR on the central nervous system have been proposed. This study will provide a sound basis for exploring the toxic mechanisms and metabolic pathways of ACR.

Toxicological Implications of Mitochondrial Localization of CYP2E1

Cytochrome P450 2E1 (CYP2E1) metabolizes an extensive array of pollutants, drugs, and other small molecules, often resulting in bioactivation to reactive metabolites. Therefore, it is unsurprising that it has been the subject of decades of research publications and reviews. However, while CYP2E1 has historically been studied in the endoplasmic reticulum (erCYP2E1), active CYP2E1 is also present in mitochondria (mtCYP2E1). Relatively few studies have specifically focused on mtCYP2E1, but there is growing interest in this form of the enzyme as a driver in toxicological mechanisms given its activity and location. Many previous studies have linked total CYP2E1 to conditions that involve mitochondrial dysfunction (fasting, diabetes, non-alcoholic steatohepatitis, and obesity). Furthermore, a large number of reactive metabolites that are formed by CYP2E1 through metabolism of drugs and pollutants have been demonstrated to cause mitochondrial dysfunction. Finally, there appears to be significant inter-individual variability in targeting to the mitochondria, which could constitute a source of variability in individual response to exposures. This review discusses those outcomes, the biochemical properties and toxicological consequences of mtCYP2E1, and highlights important knowledge gaps and future directions. Overall, we feel that this exciting area of research is rich with new and important questions about the relationship between mtCYP2E1, mitochondrial dysfunction, and pathology.

Silymarin protects against acrylamide-induced neurotoxicity via Nrf2 signalling in PC12 cells

Silymarin (SM) is a well-known antioxidant, anti-inflammatory and anti-cancer compound extracted from the milk thistle. Here, we investigated the protective effect of SM against acrylamide (AA)-induced neurotoxicity, mainly caused by oxidative stress, via activation of the nuclear transcription factor E2-related factor 2 (Nrf2) signalling pathway in PC12 cells. The MTT reduction assay was used to measure cell viability in various drug-treated groups and demonstrated that SM could increase cell viability in AA-treated PC12 cells. We then measured the reactive oxygen species (ROS) levels by the peroxide-sensitive fluorescent probe DCFH-DA and intracellular glutathione (GSH) and malondialdehyde (MDA) levels by absorption spectrophotometry. Our data revealed that SM could reduce ROS and MDA levels and increase GSH levels in AA-induced PC12 cells. To identify a potential mechanism for SM-induced protection, we measured the mRNA and protein expression levels of Nrf2 and its downstream target antioxidants glutathione peroxidase (Gpx), glutamate cysteine ligase catalytic subunit (GCLC) and glutamate cysteine ligase modifier subunit (GCLM) by quantitative real-time PCR and Western blot, respectively. The results suggested that SM could activate Nrf2 signalling and increase the expression of Nrf2, Gpx, GCLC and GCLM in AA-treated PC12 cells. In conclusion, SM can effectively alleviate AA-induced neurotoxicity in PC12 cells.

Betulinic Acid Inhibits Cell Proliferation in Human Oral Squamous Cell Carcinoma via Modulating ROS-Regulated p53 Signaling

Oral squamous cell carcinoma (OSCC) is a common cancer of the head and neck. Betulinic acid (BA) is a naturally occurring pentacyclic triterpenoid. The present study was designed to explore the effects of BA on OSCC KB cell proliferation in vitro and on implanted tumor growth in vivo and to examine the possible molecular mechanisms. The results showed that BA dose-dependently inhibited KB cell proliferation and decreased implanted tumor volume. In addition, BA significantly promoted mitochondrial apoptosis, as reflected by an increase in TUNEL⁺ cells and the activities of caspases 3 and 9, an increase in Bax expression, and a decrease in Bcl-2 expression and the mitochondrial oxygen consumption rate. BA significantly increased cell population in the G₀/G₁ phase and decreases the S phase cell number, indicating the occurrence of G₀/G₁ cell cycle arrest. ROS generation was significantly increased by BA, and antioxidant NAC treatment markedly inhibited the effect of BA on apoptosis, cell cycle arrest, and proliferation. BA dose-dependently increased p53 expression in KB cells and implanted tumors. p53 reporter gene activity and p53 binding in the promoters of Bax were significantly increased by BA. Knockdown of p53 blocked BA-induced increase in apoptosis, cell cycle arrest, and inhibition of cell proliferation. NAC treatment suppressed BA-induced increase in p53 expression. Furthermore, phosphorylation of signal transducer and activator of transcription 3 (STAT3) was increased by BA. Taken together, the data demonstrated that ROS–p53 signaling was crucial for BA-exhibited antitumor effect in OSCC. BA may serve as a potential drug for the treatment of oral cancer.

Chicoric Acid Ameliorates Lipopolysaccharide-Induced Oxidative Stress via Promoting the Keap1/Nrf2 Transcriptional Signaling Pathway in BV-2 Microglial Cells and Mouse Brain

As a major nutraceutical component of a typical Mediterranean vegetable chicory, chicoric acid (CA) has been well-documented due to its excellent antioxidant and antiobesity bioactivities. In the current study, the effects of CA on lipopolysaccharide (LPS)-stimulated oxidative stress in BV-2 microglia and C57BL/6J mice and the underlying molecular mechanisms were investigated. Results demonstrated that CA significantly reversed LPS-elicited cell viability decrease, mitochondrial dysfunction, activation of NFκB and MAPK stress pathways, and inflammation responses via balancing cellular redox status. Furthermore, molecular modeling study demonstrated that CA could insert into the pocket of Keap1 and up-regulated Nrf2 signaling and, thus, transcriptionally regulate downstream expressions of antioxidant enzymes including HO-1 and NQO-1 in both microglial cells and ip injection of LPS-treated mouse brain. These results suggested that CA attenuated LPS-induced oxidative stress via mediating Keap1/Nrf2 transcriptional pathways and downstream enzyme expressions, which indicated that CA has great potential as a nutritional preventive strategy in oxidative stress-related neuroinflammation.

Evidence of acrylamide- and glycidamide-induced oxidative stress and apoptosis in Leydig and Sertoli cells

Acrylamide (AA) is a common chemical, produced during food processing and widely used in various industries and laboratory processes. Thus, AA causes a significant risk for human and animal health. Recently published studies have suggested that reproductive toxicity of AA and glycidamide (GA) was mainly due to the oxidative stress which can lead to cell apoptosis. The present experiment was conducted to investigate the effect of oxidative stress on the apoptosis of mouse Leydig (TM3) and Sertoli (TM4) cells induced by AA and its metabolite GA. TM3 and TM4 cells were exposed to AA (10 µM and 1 mM) and GA (1 µM and 0.5 mM) for 24 h. Following the exposure time, the Leydig and Sertoli cells were evaluated for measurement of cell viability, lactate dehydrogenase activity, lipid peroxidation and hydrogen peroxide levels, apoptosis/necrosis rate, and mRNA expression levels of apoptotic genes (caspase3, Bcl-2, Bax, and p53). The present study showed that AA and GA exposure caused decrease in cell viability and increase in excessive oxidative stress and apoptosis in both cell types. In conclusion, our in vitro results demonstrate that oxidative stress probably plays a major role in AA- and GA-induced apoptosis of Leydig and Sertoli cells.

Epigallocatechin-3-gallate attenuates cerebral cortex damage and promotes brain regeneration in acrylamide-treated rats

ACR increased the rate of nestin-positive cells implying that ACR caused cell damage, and EGCG decreased the rates of nestin-positive cells against ACR suggesting that EGCG may promote cell regeneration.

Tea polyphenols ameliorate hydrogen peroxide- and constant darkness-triggered oxidative stress via modulating the Keap1/Nrf2 transcriptional signaling pathway in HepG2 cells and mice liver

Tea polyphenols alleviate oxidative stressviamodulating the Keap1/Nrf2 transcriptional signaling pathway in HepG2 cells and the liver of mice kept in constant darkness.

Involvement of Programmed Cell Death in Neurotoxicity of Metallic Nanoparticles: Recent Advances and Future Perspectives

The widespread application of metallic nanoparticles (NPs) or NP-based products has increased the risk of exposure to NPs in humans. The brain is an important organ that is more susceptible to exogenous stimuli. Moreover, any impairment to the brain is irreversible. Recently, several in vivo studies have found that metallic NPs can be absorbed into the animal body and then translocated into the brain, mainly through the blood-brain barrier and olfactory pathway after systemic administration. Furthermore, metallic NPs can cross the placental barrier to accumulate in the fetal brain, causing developmental neurotoxicity on exposure during pregnancy. Therefore, metallic NPs become a big threat to the brain. However, the mechanisms underlying the neurotoxicity of metallic NPs remain unclear. Programmed cell death (PCD), which is different from necrosis, is defined as active cell death and is regulated by certain genes. PCD can be mainly classified into apoptosis, autophagy, necroptosis, and pyroptosis. It is involved in brain development, neurodegenerative disorders, psychiatric disorders, and brain injury. Given the pivotal role of PCD in neurological functions, we reviewed relevant articles and tried to summarize the recent advances and future perspectives of PCD involvement in the neurotoxicity of metallic NPs, with the purpose of comprehensively understanding the neurotoxic mechanisms of NPs.

Effect of acrylamide-induced neurotoxicity in a primary astrocytes/microglial co-culture model

Acrylamide (AA), is a common food contaminant generated by heat processing. Astrocytes and microglia are the two major glial cell types in the brain that play pivotal but different roles in maintaining optimal brain function. The objective of this study is to investigate the neurotoxicity of AA, using a primary astrocytes/microglia co-culture model. Co-cultural cells obtained from Balb/c mice were cultured and treated with 0-1.0mM AA for 24-96h. Cell viability, reactive oxygen species (ROS) generation, oxidative end produces formation and glutathione (GSH) levels were measured. The expression of nuclear-E2-related factor 2(Nrf2), and nuclear factor kappa-beta (NF-κB) and selected down-stream genes were measured. Results showed that AA treatment led toa dose-dependent toxicity. Oxidative stress was induced as indicated by an increase of ROS, a decrease of GSH levels, and an increase in the formation of 4-hydroxynonenal-adduct and 8-hydroxy-2-deoxyguanosine-adduct. Both Nrf2 and NF-κB pathway contributed to the initiation of oxidative stress but the timing of two factors was different. Nrf2 and its related downstream genes were activated earlier than that in NF-κB pathway. In conclusion, AA-induced neurotoxicity attribute to oxidative stress via Nrf2 and NF-κB pathway. Moreover, the co-culture cell model was proven to be a viable model to study AA neurotoxicity.

3-Monochloro-1,2-propanediol (3-MCPD) induces apoptosis via mitochondrial oxidative phosphorylation system impairment and the caspase cascade pathway

3-Monochloro-1,2-propanediol (3-MCPD) is the most toxic chloropropanols compounds in foodstuff which mainly generated during thermal processing. Kidney is one of the primary target organs for 3-MCPD. Using human embryonic kidney cell (HEK293FT) as an in vitro model, we found that 3-MCPD caused concentration-dependent increase in cytoxicity as assessed by dye uptake, lactatedehydrogenase (LDH) leakage and MTT assays. HEK293FT cell treated with 3-MCPD suffered the decrease of mitochondrial membrane potential and the impairment of mitochondrial oxidative phosphorylation system, especially the reduced amount of mRNA expression and protein synthesis of electron transport chain complex II, complex IV, and complex III. More importantly, energy release (ATP synthesis) was significantly inhibited by 3-MCPD resulting from the down regulation expressions of ATP synthase (ATP6 and ATP8), as well as the loss of transmembrane potential required for synthesis of ATP. The decreased ratio of mitochondrial apoptogenic factors Bax/Bcl-2 and the cytochrome-c release from mitochondria to cytosol followed by the activation of apoptotic initiators caspase 9 and apoptotic executioners (caspase 3, caspase 6 and caspase 7) leading to apoptosis. The activation of caspase 8 and caspase 2 implied that there were probably other factors to induce the caspase-dependent apoptosis.

Momordin Ic couples apoptosis with autophagy in human hepatoblastoma cancer cells by reactive oxygen species (ROS)-mediated PI3K/Akt and MAPK signaling pathways

Momordin Ic is a principal saponin constituent of Fructus Kochiae, which acts as an edible and pharmaceutical product more than 2000 years in China. Our previous research found momordin Ic induced apoptosis by PI3K/Akt and MAPK signaling pathways in HepG2 cells. While the role of autophagy in momordin Ic induced cell death has not been discussed, and the connection between the apoptosis and autophagy is not clear yet. In this work, we reported momordin Ic promoted the formation of autophagic vacuole and expression of Beclin 1 and LC-3 in a dose- and time-dependent manner. Compared with momordin Ic treatment alone, the autophagy inhibitor 3-methyladenine (3-MA) also can inhibit apoptosis, while autophagy activator rapamycin (RAP) has the opposite effect, and the apoptosis inhibitor ZVAD-fmk also inhibited autophagy induced by momordin Ic. Momordin Ic simultaneously induces autophagy and apoptosis by suppressing the ROS-mediated PI3K/Akt and activating the ROS-related JNK and P38 pathways. Additionally, momordin Ic induces apoptosis by suppressing PI3K/Akt-dependent NF-κB pathways and promotes autophagy by ROS-mediated Erk signaling pathway. Those results suggest that momordin Ic has great potential as a nutritional preventive strategy in cancer therapy.