Endosulfan induces cell dysfunction through cycle arrest resulting from DNA damage and DNA damage response signaling pathways

Apelin-13 improves pulmonary epithelial barrier function in a mouse model of LPS-induced acute lung injury by inhibiting Chk1-mediated DNA damage

Apelin-13, a type of active peptide, can alleviate lipopolysaccharide (LPS)-induced acute lung injury (ALI). However, the specific mechanism is unclear. Cell cycle checkpoint kinase 1 (Chk1) plays an important role in DNA damage. Here, we investigated the regulatory effect of Apelin on Chk1 in ALI. Chk1-knockout and -overexpression mice were used to explore the role of Chk1 in LPS-induced ALI mice treated with or without Apelin-13. In addition, A549 cells were also treated with LPS to establish a cell model. Chk1 knockdown inhibited the destruction of alveolar structure, the damage of lung epithelial barrier function, and DNA damage in the ALI mouse model. Conversely, Chk1 overexpression had the opposite effect. Furthermore, Apelin-13 reduced Chk1 expression and DNA damage to improve the impaired lung epithelial barrier function in the ALI model. However, the high expression of Chk1 attenuated the protective effect of Apelin-13 on ALI. Notably, Apelin-13 promoted Chk1 degradation through autophagy to regulate DNA damage in LPS-treated A549 cells. In summary, Apelin-13 regulates the expression of Chk1 by promoting autophagy, thereby inhibiting epithelial DNA damage and repairing epithelial barrier function.

Mechanisms of acrolein induces toxicity in human umbilical vein endothelial cells: Oxidative stress, DNA damage response, and apoptosis

Acrolein is a ubiquitous environmental pollutant that produced by the incomplete combustion of cigarette smoke, forest fires, petroleum fuels, plastic materials, and cooking fumes. Inhalation is a common form of people exposure to acrolein, increasing evidence demonstrates that acrolein impairs the cardiovascular system by targeting vascular endothelial cells. However, the molecular mechanism of the cytotoxicity of acrolein exposure on vascular endothelial cells remains unclear. This work focused on the toxicity of acrolein on human umbilical vein endothelial cells (HUVECs). The molecular mechanism was studied based on oxidative stress, DNA damage response (DDR), and mitochondrial apoptosis pathways. After HUVECs were treated with 12.5, 25, and 50 μM acrolein for 24 h, cell viability, cell colony formation, mitochondrial membrane potential, and adenosine triphosphate content significantly reduced, and acrolein increased intracellular reactive oxygen species, apoptosis rate, and 8-hydroxy-2 deoxyguanosine (8-OHdG) level. Furthermore, p38MAPK and c-Jun N-terminal kinase signaling pathways were activated in response to oxidative stress. Moreover, acrolein induced G0/G1phase arrest, promoted the expression of γ-H2AX, activated the DDR signaling pathway (Ataxia-Telangiectasia-Mutated [ATM] and Rad-3-related/Chk1 and ATM/Chk2), and triggered the consequent cell cycle checkpoints. Finally, the protein expression of Bax/Bcl-2 and cleaved Caspase-3 was up-regulated, suggesting apoptosis was induced by triggering the mitochondrial apoptosis pathway. All these results indicated that acrolein induced HUVECs cytotoxicity by regulating oxidative stress, DNA damage, and apoptosis. This study provides a novel perspective on the mechanism of acrolein-induced cardiovascular toxicity, it will be helpful for the prevention of acrolein-induced cardiovascular disease.

Persistent pesticides: effects of endosulfan at the molecular level on the aquatic invertebrate Chironomus riparius

Although banned in multiple areas, due to its persistence in the environment, endosulfan constitutes a significant environmental concern. In this work, fourth instar Chironomus riparius larvae were exposed at environmentally relevant endosulfan concentrations of 0.1, 1, and 10 μg/L for 24 h to analyze the possible effects of this acaricide on gene expression and enzymatic activity. Transcriptional changes were studied through the implementation of a real-time polymerase chain reaction array with 42 genes related to several metabolic pathways (endocrine system, detoxification response, stress response, DNA reparation, and immune system). Moreover, glutathione-S-transferase (GST), phenoloxidase (PO), and acetylcholinesterase (AChE) activities were assessed. The five pathways were differentially altered by endosulfan exposure with significant changes in the E93, Dis, MAPR, Met, InR, GSTd3, GSTt3, MRP1, hsp70, hsp40, hsp24, ATM, PARP, Proph, and Def genes. Besides, all of the measured enzymatic activities were modified, with increased activity of GST, followed by PO and AChE. In summary, the results reflected the effects provoked in C. riparius at molecular level despite the absence of lethality. These data raise concerns about the strong alteration on different metabolic routes despite the low concentrations used. Therefore, new risk assessment strategies should consider include the effects at the sub-organismal level as endpoints in addition to the classical ecologically relevant parameters (such as survival). This endeavor will facilitate a comprehensive evaluation of toxicants in the environment.

Assessment of DNA damage induced by endosulfan in grass carp (Ctenopharyngodon idella Valenciennes, 1844)

Endosulfan is an organochlorine pesticide, which is commonly used throughout the world. It accumulates in the environment and may cause significant damage to the ecosystems, particularly to the aquatic environments. The present study was conducted to evaluate the genotoxic effect of endosulfan on the grass carp (Ctenopharyngodon idella) blood. The fish were exposed to three different concentrations, 0.75 ppb/day, 1.0 ppb/day, and 1.5ppb/day of endosulfan for 7, 14, 21, and 28 days. The study was a randomized control trial and the control group was not exposed to endosulfan. The results showed that after 7 days, the level of DNA damage in all the concentrations was significant (P < 0.05), while after 14, 21, and 28 days' trials, highly significant (P < 0.000) level of DNA damage was observed. Hence, time- and dose-dependent DNA damage was observed in fish DNA by comet assay. It is concluded from our results that with the increase in endosulfan concentration and exposure duration, the level of DNA damage also increased. As the current study showed the severe genotoxic effect of endosulfan in Ctenopharyngodon idella, therefore, the imprudent and indiscriminate use of endosulfan should be controlled and monitored by the concerned government authorities.

Silica nanoparticles induce spermatogenesis disorders via L3MBTL2-DNA damage-p53 apoptosis and RNF8-ubH2A/ubH2B pathway in mice

Silica nanoparticles (SiNPs) can reduce both quality and quantity of sperm via inhibiting the progress of meiosis and mitosis and inducing apoptosis of spermatogenic cells, however, their specific mechanism and effects on the later stage of spermatogenesis are still unclear. To investigate the effects of SiNPs on the reproductive system, male mice were treated with SiNPs (0, 1.25, 5 and 20 mg/kg.bw) via intratracheal instillation once every 3 days and for a total of 15 days. Results revealed that exposure to SiNPs induced reduction in the rate of sperm activity, histological abnormalities in seminiferous epithelium as well as apoptosis of spermatogenic cells, which are associated with decreased level of Lethal (3) malignant brain tumor like 2 (L3MBTL2) and activation of DNA damage-p53-mitochondrial apoptosis pathways. Moreover, reduction in L3MBTL2 level caused by SiNPs also led to the lower expression of RNF8-ubH2A/ubH2B pathway, thus resulting in incomplete histone-to-protamine exchange. These results suggest that the inhibition of L3MBTL2 expression caused by SiNPs not only activates DNA damage-p53-mitochondrial apoptosis pathway leading to the apoptosis of spermatogenic cells, but also inhibits RNF8-ubH2A/ubH2B pathway resulting in incomplete histone-to-protamine exchange, thereby affected spermatogenesis. This indicates that L3MBTL2 plays an important role in reproductive toxicity of males caused by SiNPs.

Endosulfan induces cardiotoxicity through apoptosis via unbalance of pro-survival and mitochondrial-mediated apoptotic pathways

Although the associations between endosulfan and adverse cardiovascular health have been reported, the toxic effects and underlying mechanism of endosulfan on the heart are not well understood. In this study, we examined the cardiotoxicity induced by endosulfan using Wistar rats and human cardiomyocytes (AC16) cells. Wistar rats were divided into control group (received corn oil alone) and three concentrations of endosulfan groups (1, 5 and 10 mg/kg·bw) by gavage. The AC16 cells were treated with three various concentrations (0, 1.25, 5, and 20 μg/mL) of endosulfan. The results showed that endosulfan induced cytotoxicity through damaging myocardial structure, decreasing the viability of cardiomyocytes, and elevating the serum levels of cardiac troponin I, heart fatty acid binding protein, aspartate aminotransferase, and reactive oxygen species (p < 0.05). Moreover, measurement of mitochondrial function showed that endosulfan could significantly decrease adenosine triphosphate levels and cytochrome c oxidase IV expression in AC16 cells (p < 0.05). In addition, endosulfan obviously inhibited Bcl-2 expression, activated the expressions of cytochrome c/Caspase-9/Caspase-3 signaling pathway, and induced the apoptosis of AC16 cells (p < 0.05). Furthermore, endosulfan significantly increased the expression of Bim, and inhibited the expressions of PI3K/Akt/FoxO3a signaling pathways in cardiomyocytes (p < 0.05). These results suggest that endosulfan may induce cardiotoxicity by inducing myocardial apoptosis resulting from activation of mitochondria-mediated apoptosis pathway and inhibition of pro-survival signaling pathways, which might be helpful in elucidating the mechanism of cardiac dysfunction induced by endosulfan.

Ivermectin induces cell cycle arrest and apoptosis of HeLa cells via mitochondrial pathway

OBJECTIVES

The aim of study was to investigate the anticancer activities of Ivermectin (IVM) and the possible mechanisms in cells level via cell proliferation inhibition, apoptosis and migration inhibition in model cancer cell HeLa.

MATERIALS AND METHODS

The MTT assay was used to study the inhibitory effect of IVM on the proliferation of Hela cells, and the cell cycle was analysed by flow cytometry. The neutral comet assay was used to study the DNA damage. The presence of apoptosis was confirmed by DAPI nuclear staining and flow cytometry. Changes in mitochondrial membrane potential and reactive oxygen species (ROS) levels were determined using Rhodamine 123 staining and DCFH-DA staining. Western blot analysis for apoptosis-related proteins was carried out. We use scratch test to analyse the antimigration potential of IVM.

RESULTS

Ivermectin can inhibit the viability of HeLa cells significantly. In addition, treatment with IVM resulted in cell cycle arrest at the G1/S phase which partly account for the suppressed proliferation. Typical apoptosis morphological changes were shown in IVM treatment cells including DNA fragmentation and chromatin condensation. At the same time, the results of flow cytometry analysis showed that the number of apoptotic cells increased significantly with the increase of IVM concentration. Moreover, we observed that the mitochondrial membrane potential collapses and the ratio of Bax/Bcl-2 in the cytoplasm increases, which induces cytochrome c release from the mitochondria to the cytoplasm, activates caspase-9/-3 and finally induces apoptosis. We also found that IVM can significantly increase intracellular ROS content. At the same time, we determined that IVM can significantly inhibit the migration of HeLa cells.

CONCLUSIONS

Our experimental results show that IVM might be a new potential anticancer drug for therapy of human cancer.

Discovery and Characterization of 4-Hydroxy-2-pyridone Derivative Sambutoxin as a Potent and Promising Anticancer Drug Candidate: Activity and Molecular Mechanism

Sambutoxin, a representative derivative of 4-hydroxy-2-pyridone, was isolated from Hericium alpestre for the first time in this study. The possible correlation between the sambutoxin-induced suppression of tumor growth and its influence on cell-cycle arrest and apoptosis was investigated. The effects of sambutoxin on reactive oxygen species (ROS) production, DNA damage, mitochondrial transmembrane potential, cell apoptosis, and the expression of related proteins were evaluated. An in vitro cell viability study demonstrated that sambutoxin could inhibit the proliferation of various cancer cells. Treatment with sambutoxin induced the production of ROS, which caused DNA damage. Furthermore, the subsequent sambutoxin-induced activation of ATM and Chk2 resulted in G2/M arrest, accompanied by decreased expression of cdc25C, cdc2, and cyclin B1. Sambutoxin induced apoptosis by activating the mitochondrial apoptosis pathway through an increased Bax/Bcl-2 ratio, loss of mitochondrial membrane potential (ΔΨm), cytochrome (Cyt) c release, caspase-9 and caspase-3 activation, and poly(ADP-ribose) polymerase (PARP) degradation. The ROS elevation induced the sustained phosphorylation of c-Jun N-terminal kinase (JNK), while SP600125, a JNK inhibitor, nearly completely reversed sambutoxin-induced apoptosis. Accordingly, an in vivo study showed that sambutoxin exhibited potential antitumor activity in a BALB/c nude mouse xenograft model without significant systemic toxicity. Moreover, the expression changes in proteins related to the G2/M phase, DNA damage, and apoptosis in vivo were consistent with those in vitro. Importantly, sambutoxin has remarkable antiproliferative effects and is a promising anticarcinogen candidate for cancer treatment.

PM2.5 induces male reproductive toxicity via mitochondrial dysfunction, DNA damage and RIPK1 mediated apoptotic signaling pathway

Recent years, air pollution has been a serious problem, and PM_2.5 is the main air particulate pollutant. Studies have investigated that PM_2.5 is a risky factor to the deterioration of semen quality in males. But, the related mechanism is still unclear. To explore the effect of PM_2.5, Sprague Dawley (SD) rats were exposed to PM_2.5 (0, 1.8, 5.4 and 16.2mg/kg.bw.) through intratracheal instillation. The exposure was performed once every 3days and continued for 30days. In vitro, GC-2spd cells were treated using 0, 50, 100, 200μg/mL PM_2.5 for 24h. The data showed that sperm relative motility rates and density were remarkably decreased, while sperm malformation rates were significantly increased with exposure to the PM_2.5. The expression of Fas/FasL/RIPK1/FADD/Caspase-8/Caspase-3 and the level of 8-OHdG expression in testes were significantly increased after exposure to PM_2.5. Additionally, in vitro the results showed that PM_2.5 inhibited cell viability, increased the release of lactate dehydrogenase (LDH) by increasing reactive oxygen species (ROS) level. And ROS induced-DNA damage led to cell cycle arrest at G0/G1 phases and proliferation inhibition. Similar to the vivo study, the expressions of Fas/FasL/RIPK1/FADD/Caspase-8/Caspase-3 in GC-2spd cells were significantly increased after exposure to PM_2.5 for 24-h. In addition, PM_2.5 decreased the levels of ATP by impairing mitochondria structures, which led to energy metabolism obstruction resulted in the decrease of sperm motility. The above three aspects together resulted in the decrease in sperm quantity and quality.

Endosulfan causes the alterations of DNA damage response through ATM-p53 signaling pathway in human leukemia cells

Exposure to pesticides results in DNA damage and genomic instability. We previously predicted that endosulfan might be associated with leukemia, but the role of endosulfan in leukemia cells has been unexplored. The aim of this study is to elucidate molecular mechanism of endosulfan-induced DNA damage response in human leukemia cells. We performed endosulfan exposure experiments in K562 cells with varying concentrations of endosulfan for 48 h and found that endosulfan lowered cell viability in a dose-dependent manner. We observed the dramatic DNA damage using comet assay and the increase of micronucleus in 75 μM endosulfan-exposed cells. Endosulfan at 75 μM caused the expression alterations of ATM and DNA repair genes such as FANCD2, and BRCA1/2 at different exposure time points (12, 24, 48 h), which was reversed by ATM inhibitor KU-55933. Endosulfan significantly increased the mRNA expression levels of p53 and GADD45A, and decreased PCNA and XRCC2 at 48 h after exposure. Flow cytometric analysis showed that endosulfan at 50 and 75 μM induced cell cycle G1 arrest, a response attributed to down-regulation of CDK6 and up-regulation of p21. We also observed that endosulfan at 50 and 75 μM induced a considerable percentage of cells to undergo apoptosis, as detected by Annexin-V binding assays. Endosulfan resulted in the activation of caspase-3, and elevated the expression levels of PUMA and the ratio of BAX/Bcl-2. These findings suggest that endosulfan caused DNA damage response throughATM-p53 signaling pathway, implicating the potential correlation between endosulfan and leukemia.

10H-3,6-Diazaphenothiazine induces G2/M phase cell cycle arrest and caspase-dependent apoptosis and inhibits cell invasion of A2780 ovarian carcinoma cells through the regulation of NF-κB and (BIRC6-XIAP) complexes

The asymptomatic properties and high treatment resistance of ovarian cancer result in poor treatment outcomes and high mortality rates. Although the fundamental chemotherapy provides promising anticancer activities, it is associated with severe side effects. The derivative of phenothiazine, namely, 10H-3,6-diazaphenothiazine (PTZ), was synthesized and reported with ideal anticancer effects in a previous paper. In this study, detailed anticancer properties of PTZ was examined on A2780 ovarian cancer cells by investigating the cytotoxicity profiles, mechanism of apoptosis, and cell invasion. Research outcomes revealed PTZ-induced dose-dependent inhibition on A2780 cancer cells (IC₅₀ =0.62 µM), with significant less cytotoxicity toward HEK293 normal kidney cells and H9C2 normal heart cells. Generation of reactive oxygen species (ROS) and polarization of mitochondrial membrane potential (ΔΨm) suggests PTZ-induced cell death through oxidative damage. The RT² Profiler PCR Array on apoptosis pathway demonstrated PTZ-induced apoptosis via intrinsic (mitochondria-dependent) and extrinsic (cell death receptor-dependent) pathway. Inhibition of NF-κB and subsequent inhibition of (BIRC6-XIAP) complex activities reduced the invasion rate of A2780 cancer cells penetrating through the Matrigel™ Invasion Chamber. Lastly, the cell cycle analysis hypothesizes that the compound is cytostatic and significantly arrests cell proliferation at G₂/M phase. Hence, the exploration of the underlying anticancer mechanism of PTZ suggested its usage as promising chemotherapeutic agent.