Cadmium-induced apoptosis in human normal liver L-02 cells by acting on mitochondria and regulating Ca(2+) signals

Transcriptomics and transmission ultrastructural examination reveals the nephrotoxicity of cadmium in laying hens

The objective of this study was to reveal the effects of cadmium (Cd) on ultrastructural changes, oxidative stress, and transcriptome expression in the kidneys of laying hens. Seventy-two healthy Hy-Line brown laying hens at 41 weeks old were randomly allocated to four treatment groups with six replicates. The control group received a basal diet without additional Cd incorporation, and the other three treatment groups received diets supplemented with 15, 30, or 60 mg Cd /kg of feed. After 6 weeks of exposure, the results show that administration of 60 mg/kg Cd significantly reduced (P < 0.05) eggshell thickness. With an increase in the Cd concentration in feed, the concentrations of renal Zn and Fe also had changed. Renal histopathology and ultrastructure also showed aggravated damage to glomeruli and renal tubules and the deformation of nuclei and mitochondria in all Cd treatment groups. With an increase in Cd in feed, the activity of glutathione peroxide (GPX) and catalase (CAT) was significantly reduced (P < 0.05), while the activity of total antioxidant capacity (T -AOC) was decreased (P < 0.05) only in the 60 mg/kg Cd group. RNA-seq analysis revealed that 410 genes displayed differential expression (≥ 1.5-fold) in the 60 mg/kg supplementation group, compared to the control group. GO and KEGG pathway analysis results showed that Cd affected many genes involved in mitochondria and ion transport. In conclusion, this study elaborates the mechanisms underlying renal toxicity caused by Cd, which might provide target candidate genes for alleviating Cd poisoning in laying hens.

Cadmium and molybdenum co-induce pyroptosis and apoptosis by PTEN/PI3K/AKT axis in the liver of ducks

Cadmium (Cd) and excessive molybdenum (Mo) have adverse impacts on animals. However, the hepatotoxicity co-induced by Cd and Mo in ducks has not been fully elucidated. In order to explore...

Cadmium induces triglyceride levels via microsomal triglyceride transfer protein (MTTP) accumulation caused by lysosomal deacidification regulated by endoplasmic reticulum (ER) Ca2+ homeostasis

Cadmium (Cd) exposure induced lipid metabolic disorder with changes in lipid composition, as well as triglyceride (TG) levels. Liver is the main organ maintaining body TG level and previous studies suggested that Cd exposure might increase TG synthesis but reduce TG uptake in liver. However, the effects of Cd exposure on TG secretion from liver and underlying mechanism are still unclear. In the present study, the data revealed that Cd exposure increased TG levels in the HepG2 cells and the cultured medium by increasing the expression of microsomal triglyceride transfer protein (MTTP), which was abrogated by siRNA knockdown of MTTP. MTTP was synergistically accumulated after Cd exposure or treated with proteasome inhibitor MG132 and lysosome inhibitor chloroquine (CQ), which suggested the Cd increased MTTP protein stability by inhibiting both the proteasome and the lysosomal protein degradation pathways. In addition, our results demonstrated that Cd exposure inhibited the lysosomal acidic degradation pathway through disrupting endoplastic reticulum (ER) Ca²⁺ homeostasis. Cd-induced MTTP protein and TG levels were significantly reduced by pretreatments of BAPTA/AM chelation of intracellular Ca²⁺, 2-APB inhibition of ER Ca²⁺ release channel inositol 1,4,5-trisphosphate receptor (IP3R) and CDN1163 activation of ER Ca²⁺ reuptake pump sarcoplasmic reticulum Ca²⁺-ATPase (SERCA). These results suggest that Cd-induced ER Ca²⁺ release impaired the lysosomal acidity, which associated with MTTP protein accumulation and contributed to increased TG levels.

A requirement for autophagy in HMGA2-induced metabolic reprogramming to support Cd-induced migration

High mobility group A2 (HMGA2) is closely related to the occurrence, development and prognosis of tumors. But the mechanism is unclear. Metabolic reprogramming is a dominant way to meet anabolic and energy requirements of tumor cells for their survival, growth and proliferation. Here, we investigated the role of metabolic reprogramming from oxidative phosphorylation (OXPHOS) to glycolysis mediated by HMGA2/autophagy axis in cadmium (Cd, CdCl₂)-induced migration. First, we found that Cd induced glycolysis and reduced OXPHOS in vivo (0.5 and 1 mg/kg, i.p. or 0.8 and 1.6 μM, i.t.) and in vitro (2 μM in A549 cells and 0.05 μM in HELF cells). Then, genetic knockdown of HMGA2 restored Cd-reduced mitochondrial mass and OXPHOS and inhibited Cd-increased glycolysis, indicating that HMGA2 was involved in Cd-induced metabolic reprogramming. 2-Deoxy-d-glucose (2DG, 5 mM), the inhibitor of glycolysis decreased Cd/HMGA2-induced cell migration and restored Cd/HMGA2-decreased OXPHOS and mitochondrial mass. Inhibition of autophagy by 3-Methyladenine (3MA, 3 mM) elucidated an essential role of autophagy in HMGA2-induced glycolysis, migration, and HMGA2-reduced OXPHOS. Overall, our study demonstrated that autophagy was required for HMGA2-mediated metabolic reprogramming, which was critical for Cd-induced migration. Targeting HMGA2 and autophagy-dependent reprogrammed metabolism may be an effective way to inhibit Cd-induced cell migration.

Induction of mitochondrial apoptosis pathway mediated through caspase-8 and c-Jun N-terminal kinase by cadmium-activated Fas in rat cortical neurons

Cadmium (Cd) is a toxic metal and an environmental pollutant and can cause neurotoxicity by inducing apoptosis. Fas (CD95/Apo-1) is a cell-surface receptor that triggers apoptosis upon ligand binding, mediated through the mitochondrial apoptotic pathway. However, the role and regulatory mechanism of Fas in Cd-induced neuronal apoptosis remain understudied. Here, we demonstrate that activation of caspase-8 and the c-Jun N-terminal kinase (JNK) pathway are mechanisms underlying Cd-induced Fas-mediated activation of the mitochondrial apoptotic pathway in rat cerebral cortical neurons. In vitro, Cd induced apoptosis in primary cortical neurons by activating caspase-8, JNK, and the mitochondrial apoptotic pathway. Fas knockdown enhanced cell viability in the presence of Cd and inhibited apoptosis by blocking Cd-activated Fas, caspase-8, and JNK. Fas knockdown also inhibited the decrease of mitochondrial membrane potential, cleavage of caspase-9/3 and poly (ADP-ribose) polymerase 1, and impaired nuclear translocation of apoptosis-inducing factor and endonuclease G. In vivo, Fas knockdown alleviated Cd-induced neuronal injury and inhibited apoptosis, activation of caspase-8, JNK, and mitochondrial apoptotic pathways in rat cerebral cortical neurons. In summary, our results demonstrate that Cd-activated Fas relays apoptotic signals from the cell surface to the mitochondria via caspase-8 and JNK activation in rat cerebral cortical neurons, leading to aggravation of the neuronal injury.

Lead (Pb) Accumulation in Human THP-1 Monocytes/Macrophages In Vitro and the Influence on Cell Apoptosis

In this study, we investigated the ability of THP-1 monocytes and macrophages to accumulate lead (Pb) in vitro, relative to Pb concentration and length of exposure. Moreover, we also evaluated the effect of Pb accumulation on cell viability and apoptosis. THP-1 monocytes and macrophages were cultured in the presence of Pb at 1.25 μg/dL, 2.5 μg/dL, 5 μg/dL, and 10 μg/dL. Pb accumulation was examined by inductively coupled plasma and confocal microscopy. The influence of Pb on cell viability, apoptosis, and necrosis was assessed using flow cytometry. The results showed that Pb was toxic to THP-1 monocytes/macrophages even at very low environmental concentrations. Despite the use of low concentrations, both monocytes and macrophages showed dose-dependent and time-dependent decreases in viability, with a simultaneous increase in the percentage of early and late apoptotic cells. Macrophages reacted more strongly to Pb than monocytes. When exposed to the same Pb concentrations, they showed lower viability and a higher percentage of necrotic cells. The incubation time positively correlated with Pb accumulation in a dose-dependent manner. The obtained results indicate that environmental exposure to low Pb concentrations may significantly impair the function of macrophages, with the increased number of apoptotic cells potentially contributing to the development of many pathologies in the brain and whole body.

Effects of cadmium on osteoblast cell line: Exportin 1 accumulation, p-JNK activation, DNA damage and cell apoptosis

Cadmium is an environmental metal pollutant that has been a focus of research in recent years, which is reported to cause bone disease; however, its skeletal toxicity and the mechanism involved are not yet fully known. Therefore, this study used MC3T3-E1 subclone 14 cells to determine the mechanism of cadmium toxicity on bone. Cadmium chloride (Cd) significantly reduced cell viability in a concentration-dependent manner. Exposure to Cd inhibited osteoblast-related proteins (Runx2, Col-1, STC2) and decreased alkaline phosphatase (ALP) activity. Cd caused Exportin-1 accumulation and induced DNA damage. Cd significantly down-regulated caspase 9 and induced cleaved-PARP, cleaved-caspase 3 protein level. Treatment with JNK inhibitor, SP600125, suppressed cadmium-induced elevation in the ratio of phosphorylation of JNK to JNK. Inhibition of caspase with pan-caspase inhibitor, Z-VAD-FMK, prevented MC3T3-E1 subclone 14 cells from cadmium-induced reduction of Runx2, STC2, caspase 9, and accumulation of cleaved PARP and cleaved caspase 3. Cd-induced cell survival enhanced by SP600125 but rescued by Z-VAD-FMK or KPT-335. These results suggest that cadmium cytotoxicity on bone involved exportin 1 accumulation, phosphorylation of JNK, induction of DNA damage and pro-apoptosis, which was induced by activation of caspase-dependent pathways.

Outcomes of Radiotherapy for Osseous Echinococcosis of Meriones meridianus

Background

Osseous cyst echinococcosis (CE) is an infectious disease that causes disability and deformity in patients, yet there is still no satisfactory treatment. Focusing on the feasibility and prognosis of radiotherapy as an adjuvant or palliative treatment for osseous CE, this study investigated the outcome of Meriones meridianus with osseous CE after radiotherapy.

Methods

The study utilized a comparison control group design with three groups of gerbils, and 240 osseous CE gerbils were randomly divided into control, 40Gy/5times, and 50Gy/5times groups. Different doses of radiotherapy were given to the gerbils, and then, the effects of radiotherapy on gerbils and lesions were observed at 3 and 6 months after radiotherapy. Statistical analysis was done using χ² test, unpaired t-test, and one-way ANOVA.

Results

Significant changes (P < 0.05) were achieved between the three groups in terms of seven parameters at 3 and 6 months, including the number of dead gerbils and lesion sites with ulceration and infection, number of dead scolices, protein content, Ca2+ concentration, the maximum diameter of lesion site, and wet weight of cysts. Except for the number of dead gerbils and lesion sites with ulceration and infection, all other parameters were observed a big difference between 3 months and 6 months in the 50Gy/5times group.

Conclusion

Radiotherapy at a dose of 50 Gy has inhibitory and therapeutic effects on osseous CE in gerbils, and radiotherapy could probably be a treatment option for persistent or recurrent osseous CE.

Influence of ferulic acid consumption in ameliorating the cadmium-induced liver and renal oxidative damage in rats

The aim of this study relates to the modulatory role of ferulic acid (FA) against cadmium (Cd)-induced oxidative stress in the liver and kidney of male Wistar albino rats. Cd is an extremely toxic industrial and environmental pollutant and is well known for its varied toxic clinical manifestations. FA is a derivative of curcumin and a ubiquitous phenolic compound having a wide range of therapeutic activities. In the current study, Cd (10 mg/kg) was administered subcutaneously for 15 and 30 days to induce hepato-renal toxicity. Cd concentration was found to be significantly high in Cd-intoxicated rats (liver > kidney) while the supplementation of FA (50 mg/kg) significantly reduces the Cd concentration in liver and kidney tissues. Reduced body and organ weights and food and water consumption and increased rectal temperature were noticed in Cd-treated rats while these parameters were significantly ameliorated in FA-supplemented rats. Liver and kidney damage induced by Cd was significantly revealed by the reduction in serum total protein contents (TPC) and increased activities of serum nitric oxide (NO) levels and hepato-nephrotoxicity marker enzymes, namely aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), lactic dehydrogenase (LDH), AST:ALT ratio, uric acid, urea, urea nitrogen, and creatinine, along with the increased levels of hepatic and renal oxidative stress markers, namely lipid peroxidation (MDA levels), lipid hydroperoxides (LOOH), protein carbonyl content (PCC), total oxidant status (TOS), and oxidative stress index (OSI) in liver and kidney tissues. In addition, the toxicity of Cd was also evidenced by a significant decrease in the levels of total thiols (TTH), total antioxidant concentration (TAC), enzymatic antioxidants (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)), and non-enzymatic antioxidants (reduced glutathione (GSH) and total free sulfhydryl groups (TSH)). Administration of FA significantly restored the serum total protein levels and activities of serum NO levels and hepatic and renal marker enzymes to normal levels in comparison with Cd-intoxicated rats. Furthermore, FA significantly reduced the oxidative stress markers and recuperated the levels of antioxidant defense in the liver and kidney as evidenced by native PAGE and spectrophotometric assays, correlation and regression analysis and multivariate analysis of variance (MANOVA), and inferring the antioxidant role of FA. Histopathological damage due to Cd intoxication in the liver and kidney is demonstrated as vasodilatation and congestion in central veins and sinusoids as well as around the glomerulus, infiltration of mixed inflammatory cells and peripheral hemorrhage, hemorrhagic and enlarged sinusoids, disorganization of the hepatic parenchyma, focal necrosis, swelling of hepatocytes, calcified tissue inside blood vessels, hepatocyte degeneration and vacuolization of liver cells, hyaline casts, degenerated glomerulus with wide space and detached basement membrane, distal tubule with wide lumen, deformed proximal tubules with detached brush border, and degeneration and hyalinization of glomerular tuft. But, FA significantly reduced the toxicity of Cd and protected the normal histological architecture of the liver and kidney tissues. Cd-intoxicated rats were associated with a significant upregulation of TNF-α, COX-2, and HSP70 proteins, whereas treatment with FA caused downregulation of the above inflammatory markers indicating the anti-inflammatory role of FA. Principal component analysis (PCA) and Euclidean similarity measure studies clearly indicate that the liver is more prone to Cd toxicity than the kidney and FA supplementation significantly prevents oxidative stress, augmenting antioxidative status, and regaining histological parameters of the liver and kidney to normal, indicating hepato-nephroprotective, antiradical, antioxidant, and anti-inflammatory effects of this phenolic compound.

The interaction of Atg4B and Bcl-2 plays an important role in Cd-induced crosstalk between apoptosis and autophagy through disassociation of Bcl-2-Beclin1 in A549 cells

Cadmium (Cd) is a highly ubiquitous detrimental metal in the environment. It is a well-known inducer of tumorigenesis, but the mechanism is not clear. In our previous study, we found that ROS-dependent Atg4B upregulation mediated Cd-induced autophagy and autophagy played an important role in Cd-induced proliferation and invasion in A549 cells. In this study, we found that Cd induced both apoptosis and autophagy in A549 cells, and apoptosis preceded autophagy. Z-VAD-FMK repressed Cd-induced LC3 and Beclin1, indicating that apoptosis was essential for Cd-induced autophagy. 3MA destroyed the recovery of mitochondrial membrane potential and increased Cd-induced CL-CASP9 and CL-CASP3 expression, suggesting that Cd-induced autophagy prevented A549 cells from apoptosis. Further study showed that Atg4B upregulation was mediated by mitochondrial dysfunction and conversely affected mitochondrial function by decreasing Bcl-2 protein expression and its localization in mitochondria, and played an important role in Cd-induced apoptosis. Moreover, Bcl-2 was involved in Cd-induced autophagy. Co-IP assay showed that Atg4B could directly bind to Bcl-2, and consequently promote disassociation of Bcl-2-Beclin1 and released autophagic protein Beclin1 to activate autophagic pathway. Taken together, our results demonstrated that the interaction of Atg4B and Bcl-2 might play an important role in Cd-induced crosstalk between apoptosis and autophagy through disassociation of Bcl-2-Beclin1. Cd-induced autophagy is apoptosis-dependent and prevents apoptotic cell death to ensure the growth and proliferation of A549 cells.

Toxic effects of arsenic trioxide on Echinococcus granulosus protoscoleces through ROS production, and Ca2+-ER stress-dependent apoptosis

Cystic echinococcosis is a severe parasitic disease that commonly affects the liver and causes abscesses or rupture into the surrounding tissues, leading to multiple complications, such as shock, severe abdominal pain, and post-treatment abscess recurrence. Currently, there are no efficient measures to prevent these complications. We previously confirmed that arsenic trioxide (As2O3) exhibited in vitro cytotoxicity against Echinococcus granulosus protoscoleces. In the present study, we aimed to explore the mechanism of As2O3-induced E. granulosus protoscoleces apoptosis. After exposing E. granulosus protoscoleces to 0, 4, 6, and 8 μM As2O3, reactive oxygen species (ROS) level was detected by fluorescence microscopy; superoxide dismutase (SOD), and caspase-3 activities were measured; intracellular Ca2+ was detected by flow cytometry; GRP-78 and caspase-12 protein levels were measured by western blot analysis. Our results showed that the expression of caspase-3 was gradually increased and the expression of SOD was gradually decreased in As2O3-treated groups of protoscoleces. Simultaneously, fluorescence microscopy and flow cytometry showed that the ROS level and the intracellular Ca2+ level were increased in a time- and dose-dependent manner. Western blot analysis showed that the expressions of GRP-78 and caspase-12 were higher in As2O3-treated groups than in the control group. These results suggest that As2O3-induced apoptosis in E. granulosus protoscoleces is related to elevation of ROS level, disruption of intracellular Ca2+ homeostasis, and endoplasmic reticulum stress. These mechanisms can be targeted in the future by safer and more effective drugs to prevent recurrence of cystic echinococcosis.

The Effects of Agaricus blazei Murill Polysaccharides on Cadmium-Induced Apoptosis and the TLR4 Signaling Pathway of Peripheral Blood Lymphocytes in Chicken

In this study, we investigated the effects of Agaricus blazei Murill polysaccharides (ABP) on cadmium (Cd)-induced apoptosis and the TLR4 signaling pathway of chicken peripheral blood lymphocytes (PBLs). Seven-day-old healthy chickens were randomly divided into four groups, and each group contained 20 males. The cadmium-supplemented diet group (Cd group) was fed daily with full feed that contained 140 mg cadmium chloride (CdCl₂)/kg and 0.2 mL saline. The A. blazei Murill polysaccharide diet group (ABP group) was fed daily with full feed with 0.2 mL ABP solution (30 mg/mL) by oral gavage. The cadmium-supplemented plus A. blazei Murill polysaccharide diet group (Cd + ABP group) was fed daily with full feed containing 140 mg CdCl₂/kg and 0.2 mL ABP solution (30 mg/mL) by gavage. The control group was fed daily with full feed with 0.2 mL saline per day. We measured the apoptosis rate and messenger RNA (mRNA) levels of apoptosis genes (caspase-3, Bax, and Bcl-2), the mRNA levels of TLR4 and TLR4 signaling pathway-related factors (MyD88, TRIF, NF-κB, and IRF3), the TLR4 protein expression, and the concentrations of inflammatory cytokines (IL-1β, IL-6, and TNF-α) in chicken PBLs. The results showed that the PBL apoptosis rate was significantly increased, the mRNA levels of caspase-3 and Bax were significantly increased, while that of Bcl-2 was significantly reduced. The Bax/Bcl-2 ratio was significantly increased in the Cd group at 20, 40, and 60 days after treatment compared with that in the control group. After treatment with ABP, the above changes were clearly suppressed. At the same time, ABP reduced the concentrations of IL-1β, IL-6, and TNF-α induced by Cd. We also found that ABP inhibited the TLR4 mRNA level and protein expression and inhibited the mRNA levels of MyD88, TRIF, NF-κB, and IRF3. The results demonstrated that Cd could induce apoptosis, activate the TLR4 signaling pathway, and induce the expression of inflammatory cytokines in chicken PBLs, and that the administration of ABP clearly inhibited Cd-induced effects on chicken PBLs.

The involvement of the mitochondrial pathway in manganese-induced apoptosis of chicken splenic lymphocytes

The purpose of this study was to investigate the effect of excess manganese (Mn)-induced cytotoxicity on apoptosis in chicken splenic lymphocytes. Chicken splenic lymphocytes were cultured in medium in the absence and presence of manganese (II) chloride (MnCl2) (2 × 10(-4), 4 × 10(-4), 6 × 10(-4), 8 × 10(-4), 10 × 10(-4), and 12 × 10(-4) mM), in N-acetyl-l-cysteine (NAC) (1 mM), and the combination of MnCl2 and NAC for 12, 24, 36, and 48 h. Tests were performed on morphologic observation, reactive oxygen species (ROS) and malondialdehyde (MDA) content, manganese superoxide dismutase (Mn-SOD) and glutathione peroxidase (GSH-Px) activities, B-cell lymphoma-2 (Bcl-2), Bcl-2 associated X protein (Bax), p53, and calmodulin (CaM) messenger RNA (mRNA) expression, Caspase-3 mRNA and protein expression, intracellular free Ca(2+) ([Ca(2+)]i), and mitochondrial transmembrane potential (ΔΨm). Our research indicated that excess Mn induced ROS and MDA content, inhibited Mn-SOD and GSH-Px activities, induced Bax and p53 mRNA expression, inhibited Bcl-2 and CaM mRNA expression, induced Caspase-3 mRNA and protein expression, upregulated [Ca(2+)]i, inhibited ΔΨm, and induced apoptosis in a dose effect. NAC relieved excess Mn-caused the changes of all above factors. Mn-induced oxidative injuries were alleviated by treatment with NAC, an ROS scavenger. The above results demonstrated that excess Mn caused oxidative stress and apoptosis via mitochondrial pathway in chicken splenic lymphocytes.

The Effects of Cadmium at Low Environmental Concentrations on THP-1 Macrophage Apoptosis

Cadmium at environmental concentrations is a risk factor for many diseases, including cardiovascular and neurodegenerative diseases, in which macrophages play an important role. The aim of this study was to evaluate the effects of cadmium at low environmental (nanomolar) concentrations on apoptotic processes in THP-1(acute monocytic leukemia cells line)-derived macrophages, with special focus on mitochondrial events involved. Macrophages were incubated with various cadmium chloride (CdCl₂) solutions for 48 h at final concentrations of 5 nM, 20 nM, 200 nM and 2 µM CdCl₂. Cell viability was measured using flow cytometry. Flow cytometric measurement (annexin V/FITC (annexin V/fluorescein isothiocyanate) and PI (propidium iodide) double staining) was used to quantify the extent of apoptosis. Fluorescence and confocal microscopy were used for imaging of apoptosis process. Changes in mitochondrial membrane potential were monitored using cytofluorimetry after cell staining with JC-1(5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazol-carbocyane iodide) probe. Mitochondrial ROS (reactive oxygen species) levels were measured cytofluorimetrically after incubation of cells with mitochondrial superoxide indicator (MitoSOX) red fluorescent marker. The mRNA expression of Bcl-2 and Bax was analysed with qRT-PCR. Our study demonstrates that cadmium, even at low environmental concentrations, exerts mitochondrial toxicity in THP-1 macrophages. Forty-eight-hour exposure to very low concentrations reduces cell viability and results in cell death by apoptosis and necrosis. The decrease in mitochondrial membrane potential, increased ROS production, increased Bax and decreased Bcl-2 mRNA expression are mitochondrial events involved in cadmium-induced apoptosis.

Effects of cadmium on cell proliferation, apoptosis, and proto-oncogene expression in zebrafish liver cells

Cadmium (Cd) is one of the major transitional metal that has toxic effects in aquatic organisms and their associated ecosystem; however, its hepatic toxicity and carcinogenicity are not very well characterized. We used a zebrafish liver (ZFL) cell line as a model to investigate the mechanism of Cd-induced toxicity on hepatocytes. Our results showed that Cd can be effectively accumulated in ZFL cells in our exposure experiments. Cell cytotoxicity assays and flow cytometer measurements revealed that Cd(2+) stimulated ZFL cell proliferation with decreasing apoptotic cell numbers indicating potentially tumorigenic effects of Cd in ZFL cells. Gene expression profiles also indicated that Cd downregulated oncogenes p53 and rad51 and upregulated immediate response oncogenes, growth arrest and DNA damage-inducible (gadd45) genes, and growth factors. We also found dramatic changes in the gene expression of c-jun and igf1rb at different exposure time points, supporting the notion that potentially tumorigenic of Cd-is involved in the activation of immediate early genes or genes related to apoptosis in cancer promotion.

Oxidative stress and Ca(2+) signals involved on cadmium-induced apoptosis in rat hepatocyte

Cadmium (Cd) is an important industrial and environmental pollutant. In animals, the liver is the major target organ of Cd toxicity. In this study, rat hepatocytes were treated with 2.5∼10 μM Cd for various durations. Studies on nuclear morphology, chromatin condensation, and apoptotic cells demonstrate that Cd concentrations ranging within 2.5∼10 μM induced apoptosis. The early-stage marker of apoptosis, i.e., decreased mitochondrial membrane potential, was observed as early as 1.5 h at 5 μM Cd. Significant (P < 0.01) reactive oxygen species (ROS) production at 5 μM Cd and 0.75 h occurred prior to the decrease of the mitochondrial membrane potential, suggesting the involvement of ROS in mitochondrial membrane damage. Glutathione (GSH) level significantly decreased after cell treatment with 5 and 10 μM Cd after 12 h (P < 0.01). Meanwhile, the intracellular free Ca(2+) concentration ([Ca(2+)] i ) of Cd-exposed cells significantly increased (P < 0.01) at 1.5 h, and pretreatment with the calcium chelator Bapta-AM partially blocked Cd-induced apoptosis. This finding indicated that the elevation of [Ca(2+)] i may play an important role in apoptosis. Overall, these results showed that oxidative stress and Ca(2+) signaling were critical mediators of the Cd-induced apoptosis of rat hepatocytes.

Surfactin-induced apoptosis through ROS-ERS-Ca2+-ERK pathways in HepG2 cells

Although surfactin is able to inhibit cancer cell proliferation and to induce cancer cell apoptosis, the molecular mechanism responsible for this process remain elusive. In this study, the signaling network underlying the apoptosis of human hepatoma (HepG2) cells induced by surfactin was investigated. It is found that the reaction oxygen species (ROS) production and intracellular calcium ([Ca(2+)]i) accumulation are both induced HepG2 cells apoptosis. The [Ca(2+)]i exaltation was partly depended on the Ca(2+) release from inositol 1,4,5-trisphosphate (IP3) and ryanodine (Ry) receptors channels, which both triggered endoplasmic reticulum stress (ERS). The results showed that surfactin induced the ROS production and ROS production led to ERS. The occurrence of ERS increased the [Ca(2+)]i level and the processes associated with blocking extracellular signal-regulated kinase (ERK) pathway. According to a comprehensive review of all the evidence, it is concluded that surfactin induces apoptosis of HepG2 cells through a ROS-ERS-Ca(2+) mediated ERK pathway.

Protective effects of Korean red ginseng extract on cadmium-induced hepatic toxicity in rats

Korean red ginseng is known to regulate the immune system and help the body struggle infection and disease. Cadmium is widely distributed in the environment due to its use in industry. Exposure to cadmium is problematic causing organ dysfunction. This study was conducted to evaluate the protective effect of Korean red ginseng extract (RGE) against cadmium-induced hepatotoxicity in rats. In experiments, animals were orally administrated with RGE (25, 50 mg/kg) for 7 d and then intravenously injected with cadmium (CdCl2, 4 mg/kg) to induce acute hepatotoxicity. Cadmium caused the elevated levels of alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase in serum. In contrast, pretreatment with RGE significantly reduced those serum indexes related with liver damage. In histopathological analysis, RGE decreased the centrilobular necrosis around central veins and the peripheral hemorrhage around portal triads. Moreover, RGE restored the deficit in hepatic glutathione level resulting from cadmium treatment. RGE also inhibited the increase in the expression of Bad, a representative apoptosis marker protein, induced by cadmium treatment. Collectively, these results demonstrate that RGE can reduce the cadmium-induced hepatic toxicity, partly via anti-oxidative and anti-apoptotic process.

Determination of a threshold dose to reduce or eliminate CdTe-induced toxicity in L929 cells by controlling the exposure dose

With the widespread use of quantum dots (QDs), the likelihood of exposure to quantum dots has increased substantially. The application of quantum dots in numerous biomedical areas requires detailed studies on their toxicity. In this study, we aimed to determine the threshold dose which reduced or eliminated CdTe-induced toxicity in L929 cells by controlling the exposure dose. We established a cellular model of acute exposure to CdTe QDs. Cells were exposed to different concentrations of CdTe QDs (2.2 nm and 3.5 nm) followed by illustrative cytotoxicity analysis. The results showed that low concentrations of CdTe QDs (under 10 µg/mL) promoted cell viability, caused no obvious effect on the rate of cell apoptosis, intracellular calcium levels and changes in mitochondrial membrane potential, while high concentrations significantly inhibited cell viability. In addition, reactive oxygen species in the 10 µg/mL-treated group was significantly reduced compared with the control group. In summary, the cytotoxicity of CdTe QDs on L929 cell is dose-dependent, time-dependent and size-dependent. Low concentrations of CdTe QDs (below 10 µg/mL) may be nontoxic and safe in L929 cells, whereas high concentrations (above 10 µg/mL) may be toxic resulting in inhibition of proliferation and induction of apoptosis in L929 cells.

Cadmium induces thymocyte apoptosis via caspase-dependent and caspase-independent pathways

Based on our recent findings that 25 µM cadmium triggers oxidative stress-mediated caspase-dependent apoptosis in murine thymocytes, this study is designed to explore whether Cd also induces caspase-independent apoptosis. We found that pretreatment with caspase inhibitors fails to prevent Cd-induced apoptosis completely, suggesting the possibility of an additional pathway. Western blot and flow cytometry techniques indicated marked expression of apoptosis-inducing factor and endonuclease G in nuclear fraction, signifying their translocation from mitochondria to nucleus. Intracellular Ca²⁺ and reactive oxygen species (ROS) levels significantly raised by Cd were restored by ruthenium red, which had no influence on mitochondrial membrane depolarization and caspase activity and apoptosis. Using cyclosporin A, ROS formation and mitochondrial membrane depolarization were completely abolished, whereas apoptosis was partly attenuated. These results clearly demonstrate more than one apoptotic pathway in thymocytes and support the role of mitochondrial permeability transition pore in the regulation of caspase-independent cell death triggered by Cd.

A common response to common danger? Comparison of animal and plant signaling pathways involved in cadmium sensing

Exposure to cadmium results in disturbances in cell homeostasis in all living organisms. The first response to stress factors, including cadmium, is activation of signal transduction pathways that mobilize cell defense mechanisms. The aim of this review is a comparison between the signaling network triggered by Cd in plants and animals. Despite differences in the structure and physiology of plant and animal cells, their cadmium signal transduction pathways share many common elements. These elements include signaling molecules such as ROS, Ca(2+) and NO, the involvement of phospholipase C, mitogen-activated protein kinase cascades, and activation of transcription factors. Undoubtedly, both animals and plants also possess specific signaling pathways. In case of animals, Wnt/β-catenin, sonic hedgehog and oestorgen signaling are engaged in the transduction of cadmium signal. Plant specific signal transduction pathways include signaling mediated by plant hormones. The role of ethylene and jasmonic, salicylic and abscisic acid in plant response to cadmium is also discussed.

A novel chenodeoxycholic acid-verticinone ester induces apoptosis and cell cycle arrest in HepG2 cells

In this study, the in vitro antitumor activity of chenodeoxycholic acid-verticinone ester (CDCA-Ver), a novel compound and its underlying mechanisms were evaluated. Results showed that CDCA-Ver significantly inhibited HepG2 cell viability in a both dose- and time-dependent manner, moreover CDCA-Ver induced apoptotic cell death and G(0)/G(1) cell cycle arrest in HepG2 cells. ROS generation, loss of balance of Bax/Bcl-2 ratio, loss of mitochondrial transmembrane potential, activation of caspases and elevation of intracellular free Ca(2+) concentration were involved in the CDCA-Ver induced apoptosis pathway in HepG2 cells. We concluded that CDCA-Ver may be a potential candidate for the therapy of cancer.

Cadmium-induced oxidative stress and apoptotic changes in the testis of freshwater crab, Sinopotamon henanense

Cadmium (Cd), one of the most toxic environmental and industrial pollutants, is known to exert gonadotoxic and spermiotoxic effects. In the present study, we examined the toxic effect of Cd on the testis of freshwater crab, Sinopotamon henanense. Crabs were exposed to different Cd concentrations (from 0 to 116.00 mg·L(-1)) for 7 d. Oxidative stress and apoptotic changes in the testes were detected. The activities of SOD, GPx and CAT initially increased and subsequently decreased with increasing Cd concentrations, which was accompanied with the increase in malondialdehyde (MDA) and H(2)O(2) content in a concentration-dependent manner. Typical morphological characteristic and physiological changes of apoptosis were observed using a variety of methods (HE staining, AO/EB double fluorescent staining, Transmission Electron Microscope observation and DNA fragmentation analysis), and the activities of caspase-3 and caspase-9 were increased in a concentration-dependent manner after Cd exposure. These results led to the conclusion that Cd could induced oxidative damage as well as apoptosis in the testis, and the apoptotic processes may be mediated via mitochondria-dependent apoptosis pathway by regulating the activities of caspase-3 and caspase-9.

Cytoarchitectural alterations in kidney of Wistar rat after oral exposure to cadmium chloride

Male Wistar rats were randomly divided into three groups--A, B and C. A dose of 5 mg and 10 mg of cadmium chloride/kg body weight/day was orally administered to groups B and C, respectively. Rats from group A served as control. Rats were sacrificed on 1st, 2nd, 4th, 6th, and 8th week after initiation of the experiment. Kidneys were removed immediately, fixed in Bouin's fixative, routinely processed and stained with hematoxylin and eosin. The present study showed that the histopathological changes were caused in kidney of rats by cadmium exposure. The changes noticed were mainly--the glomerular swelling (at initial stage), the shrinkage of glomerulus (at later stage), the tubular dilatation, hypertrophy of tubular epithelium, degeneration of glomerulus and renal tubules and deposition of eosin-positive substances in the glomerulus and renal tubules. However, lesions were depended upon the doses and duration of the treatment.

Consistent chemical form of Cd in liver and kidney tissues in rats dosed with a range of Cd treatments: XAS of intact tissues

X-ray absorption spectroscopy of frozen intact tissues shows that in rats exposed to a range of treatments involving cadmium, alone or in combination with other metal ions, the coordination environment of cadmium is consistent in both the liver and kidney. Comparison of the spectra from the rat tissues to biologically relevant model compounds indicates that the vast majority of the cadmium is bound to metallothionein in these tissues.

Acetaminophen-induced cytotoxicity on human normal liver L-02 cells and the protection of antioxidants

In vitro cell models, which can partially mimic in vivo responses, offer potentially sensitive tools for toxicological assessment. The objective of this study was to explore the possible mechanisms of acetaminophen (AP)-induced toxicity in human normal liver L-02 cells. The expression of the CYP2E1 enzyme, which is reported to transform AP to its toxic metabolites, was higher in L-02 than in Hep3B cells. Further cell viability and reduced glutathione (GSH) depletion after AP treatment were examined. After exposure to AP for 24 h, cell viability decreased in a concentration-dependent manner. Concentration-dependent GSH depletion was also observed after AP treatment for 48 h, indicating oxidative stress had occurred in L-02 cells. The effects of D, L-buthionine-(S, R)-sulfoximine (BSO), an inhibitor of GSH biosynthesis, and N-acetylcysteine (NAC), a precursor of GSH synthesis, on the cytotoxicity induced by AP were also investigated. BSO aggravated the cytotoxicity induced by AP while NAC ameliorated such cell death. Further results showed that 10 mM AP caused cell apoptosis after 48 h treatment based on the DNA fragmentation assay and western blot of caspase-3 activation, respectively. In addition, the protective effects of various well-known antioxidants against AP-induced hepatotoxicity were observed. Taken together, these results indicate that oxidative stress and cellular apoptosis are involved in AP-induced toxicity in human normal liver L-02 cells, and this cell line is a suitable in vitro cell model for AP hepatotoxicity study.

HCCS1 overexpression induces apoptosis via cathepsin D and intracellular calcium, and HCCS1 disruption in mice causes placental abnormality

Hepatocellular carcinoma suppressor 1 (HCCS1) was discovered as a novel tumor suppressor gene. We recently observed that adenovirus-mediated gene transfer of HCCS1 leads to cytotoxicity to human hepatocarcinoma cells. Here, we have demonstrated that adenovirus-mediated overexpression of HCCS1 induces apoptosis in hepatocarcinoma cells and have further characterized the apoptotic cascade. The results showed that lysosomal cathepsin D is released into the cytosol in response to HCCS1 overexpression and consequently triggers Bax insertion into the mitochondrial membrane, which leads to the release of cytochrome c. In addition, HCCS1 overexpression can induce an increase in intracellular free Ca(2+) concentration, which also results in cytochrome c release. The released cytochrome c activates downstream caspases, leading to the occurrence of the late stages of apoptosis. Moreover, we demonstrated that the disruption of HCCS1 in mice leads to embryonic lethality, accompanied by abnormal labyrinth architecture resulting from the excessive proliferation of trophoblast cells in the placenta. These results suggest that HCCS1 plays a role in apoptosis regulation and development.