2-Methoxyestradiol induces endoreduplication through the induction of mitochondrial oxidative stress and the activation of MAPK signaling pathways

Multicolor-Encoded DNA Framework Enables Specific and Amplified In Situ Detection of the Mitochondrial Apoptotic Signaling Pathway

Monitoring the molecular activation networks of cellular processes through fluorescence imaging to accurately elucidate the signaling pathways of mitochondrial apoptosis and the regulation of upstream and downstream molecules remains a current major challenge. In this work, a multicolor-encoded tetrahedral DNA framework (meTDF) carrying two pairs of catalytic hairpins is synthesized to monitor the intracellular upstream manganese superoxide dismutase (MnSOD) mRNA and the downstream cytochrome c (Cyt c) molecules for specific and sensitive detection of the mitochondrial apoptotic signaling pathway. These two types of molecules can trigger catalytic hairpin assembly (CHA) reactions with accelerated reaction kinetics for the hairpin pairs confined on meTDF to show highly amplified fluorescence for sensitive and simultaneous detection of MnSOD mRNA and Cyt c with detection limits of 3.7 pM and 0.23 nM in vitro, respectively. Moreover, the high stability and biocompatibility of the designed meTDF can facilitate efficient delivery of the probes into cells to monitor intracellular MnSOD mRNA and Cyt c for specific detection of the mitochondrial apoptosis pathway regulated by different drugs. With the successful demonstration of their robust capability, the meTDF nanoprobes can thus open new opportunities for detecting cell apoptotic mechanisms for studying the corresponding apoptotic signaling pathways and for screening potential therapeutic drugs.

Aspergillus awamori attenuates ochratoxin A-induced renal and cardiac injuries in rabbits by activating the Nrf2/HO-1 signaling pathway and downregulating IL1β, TNFα, and iNOS gene expressions

Ochratoxin A (OTA) is one of the most dangerous and that pollute agricultural products, inducing a variety of toxic effects in humans and animals. The current study explored the protective effect of different concentrations of Aspergillus awamori (A. awamori) against OTA (0.3 mg/kg diet) induced renal and cardiac damage by exploring its mechanism of action in 60 New Zealand white male rabbits. Dietary supplementation of A. awamori at the selected doses of 50, 100, and 150 mg/kg diet, respectively, for 2 months significantly improved the rabbit's growth performance; modulated the suppressed immune response and restored the altered hematological parameters; reduced the elevated levels of renal injury biomarkers such as urea, creatinine, and alkaline phosphatase; and increased serum total proteins concentrations. Moreover, it also declined enzymatic activities of cardiac injury biomarkers, including AST, LDH, and CK-MB. A. awamori alleviated OTA-induced degenerative and necrotic changes in the kidney and heart of rabbits. Interestingly, A. awamori upregulated Nrf2/OH-1 signaling pathway. Therefore enhanced TAC, CAT, and SOD enzyme activities and reduced OTA-induced oxidative and nitrosative stress by declining iNOS gene expression and consequently lowered MDA and NO levels. In addition to attenuating renal and cardiac inflammation via reducing IL-1β, TNF-α gene expressions in a dose-dependent response. In conclusion,this is the first report to pinpoint that dietary incorporation of A. awamori counteracted OTA-induced renal and cardiac damage by potentiating the rabbit's antioxidant defense system through its potent antioxidant, free radical scavenging, and anti-inflammatory properties in a dose-dependent response. Based on our observations, A. awamori could be utilized as a natural protective agent against ochratoxicosis in rabbits.

Evaluation of Ascorbic Acid Niosomes as Potential Detoxifiers in Oxidative Stress-induced HEK-293 Cells by Arsenic Trioxide

Background

As an environmental contaminant, Arsenic (As) poses many risks to human health. Increased Oxidative Stress (OS) and decreased antioxidant cell defense are the suggested mechanisms of carcinogenicity and toxicity of As. As a powerful antioxidant and water-soluble compound, vitamin C protects cells and tissues against oxidation and has a wide range of healing properties.

Objectives

The current study aimed to formulate a suitable ascorbic acid (vitamin C) niosome and compare it with vitamin C in preventing As-induced toxicity in HEK-293 cells.

Methods

Various formulas of vitamin C niosomes were prepared by C-SPAN mixed with cholesterol. The physicochemical characteristics of niosomal formulations, including load size, zeta-potential, and the drug release profile, were evaluated in HEK-293 cells. Then, OS biomarkers such as total reactive oxygen species (ROS), malondialdehyde (MDA), catalase (CAT), Antioxidant Capacity (TAC), and superoxide dismutase (SOD) activities determined the protective effects of vitamin C niosomes compared with vitamin C against As-induced toxicity.

Results

The particle size and zeta potential of the optimal vitamin C niosome were 163.2 ± 6.1 nm and 23.3 ± 3.5 mV, respectively. Arsenic increased ROS and MDA levels while decreasing CAT, TAC, and SOD activities in the HEK-293 cell line. Finally, the vitamin C niosome decreased OS and increased antioxidant properties more than vitamin C.

Significance

Vitamin C niosome was more effective than vitamin C in treating As-induced toxicity in vitro.

2-Hydroxyestradiol Overcomes Mesenchymal Stem Cells-Mediated Platinum Chemoresistance in Ovarian Cancer Cells in an ERK-Independent Fashion

Ovarian cancer (OC) is the second most common type of gynecological malignancy. Platinum (Pt)-based chemotherapy is the standard of care for OC, but toxicity and acquired chemoresistance has proven challenging. Recently, we reported that sensitivity to platinum was significantly reduced in a co-culture of OC cells with MSC. To discover compounds capable of restoring platinum sensitivity, we screened a number of candidates and monitored ability to induce PARP cleavage. Moreover, we monitored platinum uptake and expression of ABC transporters in OC cells. Our results showed that 2-hydroxyestradiol (2HE2), a metabolite of estradiol, and dasatinib, an Abl/Src kinase inhibitor, were significantly effective in overcoming MSC-mediated platinum drug resistance. Dasatinib activity was dependent on ERK1/2 activation, whereas 2HE2 was independent of the activation of ERK1/2. MSC-mediated platinum drug resistance was accompanied by reduced intracellular platinum concentrations in OC cells. Moreover, MSC co-cultured with OC cells resulted in downregulation of the expression of cellular transporters required for platinum uptake and efflux. Exposure to 2HE2 and other modulators resulted in an increase in intracellular platinum concentrations. Thus, 2HE2 and dasatinib might act as sensitizers to restore platinum drug sensitivity to OC cells and thus to limit TME-mediated chemoresistance in OC.

2-Methoxyestradiol Reverses the Pro-Carcinogenic Effect of L-Lactate in Osteosarcoma 143B Cells

BACKGROUND/AIM

According to the reverse Warburg effect, tumor cells may metabolize lactate as an energy source and shuttle L-lactate to neighboring cancer cells, adjacent stroma, and vascular endothelial cells, thus inducing metabolic reprogramming. An increased tumor L-lactate level strictly correlates with increased metastasis, tumor recurrence and a poor outcome. A potent anticancer agent that may act on L-lactate activated cells is 2-metoxyestradiol. Thus, the aim of the study was to evaluate whether a potent anticancer agent, 2-methoxyestradiol, is able to reverse L-lactate-induced metabolic reprogramming in osteosarcoma 143B cells.

MATERIALS AND METHODS

We used flow cytometry in order to determine cell death, autophagy, expression of KI-67, mitochondrial membrane depolarization. We performed cell proliferation assay in order to determine cell viability and cell migration assay to determine invasive potential of osteosarcoma cells. While, CalcuSyn software was used in order to evaluate the interaction between 2-methoxyestradiol and L-lactate.

RESULTS

We demonstrated that 2-methoxyestradiol abolished L-lactate-induced migration and proliferation of osteosarcoma cells. Moreover, we observed that this effect was associated with regulation of Ki-67 and induction of autophagy.

CONCLUSION

2-Methoxyestradiol is a potent anticancer agent also under metabolic reprogramming conditions.

Selective eradication of cancer displaying hyperactive Akt by exploiting the metabolic consequences of Akt activation

Akt activation in human cancers exerts chemoresistance, but pan-Akt inhibition elicits adverse consequences. We exploited the consequences of Akt-mediated mitochondrial and glucose metabolism to selectively eradicate and evade chemoresistance of prostate cancer displaying hyperactive Akt. PTEN-deficient prostate cancer cells that display hyperactivated Akt have high intracellular reactive oxygen species (ROS) levels, in part, because of Akt-dependent increase of oxidative phosphorylation. High intracellular ROS levels selectively sensitize cells displaying hyperactive Akt to ROS-induced cell death enabling a therapeutic strategy combining a ROS inducer and rapamycin in PTEN-deficient prostate tumors in mouse models. This strategy elicited tumor regression, and markedly increased survival even after the treatment was stopped. By contrast, exposure to antioxidant increased prostate tumor progression. To increase glucose metabolism, Akt activation phosphorylated HK2 and induced its expression. Indeed, HK2 deficiency in mouse models of Pten-deficient prostate cancer elicited a marked inhibition of tumor development and extended lifespan.

L-ascorbic acid and α-tocopherol attenuate arsenic trioxide-induced toxicity in H9c2 cardiomyocytes by the activation of Nrf2 and Bcl2 transcription factors

Arsenic trioxide (As₂O₃) is a potent drug for the treatment of acute promyelocytic leukemia (APL) and has achieved remarkable remissions in patients. Unfortunately, clinical reports have shown that the treatment is associated with cardiotoxicity. Many efforts have been made to mitigate drug-mediated cardiac damage using naturally occurring antioxidant compounds possessing free radical scavenging activity. The present investigation aims to explore protective role of L-ascorbic acid (L-AA) and α-tocopherol (α-TOC) from As₂O₃-induced oxidative stress in H9c2 cardiomyocytes through the evaluation of Nrf2 (nuclear factor erythroid 2-related factor 2) and Bcl-2 (B-cell lymphoma 2) transcription factors. The in vitro study was conducted using H9c2 cardiomyocytes. The evaluation of total antioxidant capacity, mitochondrial membrane potential, cellular calcium concentration and reactive oxygen species generation was performed. Oxidative stress (Nrf2) and anti-apoptotic (Bcl2) signaling indicators were measured by reverse transcriptase polymerase chain reaction. A depletion of the total antioxidant capacity and mitochondrial transmembrane potential were observed in As₂O₃-treated cardiomyocytes. In addition, the cellular calcium concentration and ROS generation were found to be increased on treatment with As₂O₃ with the alterations in the activity of transcription factors, Nrf2 and Bcl2. Co-treatment of antioxidant vitamins with As₂O₃ resulted in a significant reversal of oxidative stress and alteration on the antioxidant defense through the activation of Nrf2 and Bcl2. L-AA and α-TOC alleviates As₂O₃-induced oxidative stress in cardiac cells by activating Nrf2 and Bcl2 transcription factors that results in increased cell survival and prevents apoptosis.

Nitraria retusa fruit prevents penconazole-induced kidney injury in adult rats through modulation of oxidative stress and histopathological changes

CONTEXT

Nitraria retusa (Forssk.) Asch. (Nitrariaceae) is a medicinal plant which produces edible fruits whose antioxidant activity has been demonstrated.

OBJECTIVE

The current study elucidates the potential protective effect of N. retusa fruit aqueous extract against nephrotoxicity induced by penconazole, a triazole fungicide, in the kidney of adult rats.

MATERIALS AND METHODS

Adult Wistar rats were exposed either to penconazole (67 mg/kg body weight), or to N. retusa extract (300 mg/kg body weight) or to their combination. Penconazole was administered by intra-peritoneal injection every 2 days from day 7 until day 15, the sacrifice day, while N. retusa extract was administered daily by gavage during 15 days. Oxidative stress parameters, kidney biomarkers and histopathological examination were determined.

RESULTS

Nitraria retusa extract administration to penconazole treated rats decreased kidney levels of malondialdehyde (-10%), hydrogen peroxide (-12%), protein carbonyls (PCOs, -11%) and advanced oxidation protein products (AOPP, -16%); antioxidant enzyme activities: catalase (-13%), superoxide dismutase (-8%) and glutathione peroxidase (GPx, -14%), and the levels of non-enzymatic antioxidants: non-protein thiols (-9%), glutathione (-7%) and metallothionein (-12%). Furthermore, this plant extract prevented kidney biomarker changes by reducing plasma levels of creatinine, urea, uric acid and LDH and increasing those of ALP and GGT. Histopathological alterations induced by penconazole (glomeruli fragmentation, Bowman's space enlargement, tubular epithelial cells necrosis and infiltration of inflammatory leucocytes) were attenuated following N. retusa administration.

DISCUSSION AND CONCLUSION

Our results indicated that N. retusa fruit extract had protective effects against penconazole-induced kidney injury, which could be attributed to its phenolic compounds.

Cytoprotective effects of essential oil of Pinus halepensis L. against aspirin-induced toxicity in IEC-6 cells

CONTEXT

Essential oils from Pinus species have been reported to have various therapeutic properties.

OBJECTIVE

This study was undertaken to identify the chemical composition and cytoprotective effects of the essential oil of Pinus halepensis L. against aspirin-induced damage in cells in vitro.

MATERIAL AND METHODS

The cytoprotection of the oil against toxicity of aspirin on the small intestine epithelial cells IEC-6 was tested.

RESULTS

The obtained results have shown that 35 different compounds were identified. Aspirin induced a decrease in cell viability, and exhibited significant damage to their morphology and an increase in superoxide dismutase (SOD) and catalase (CAT) activities. However, the co-treatment of aspirin with the essential oil of Pinus induced a significant increase in cell viability and a decrease in SOD and CAT activities.

CONCLUSION

Overall, these finding suggest that the essential oil of Pinus halepensis L. has potent cytoprotective effect against aspirin-induced toxicity in IEC-6 cells.

A bis-sulphamoylated estradiol derivative induces ROS-dependent cell cycle abnormalities and subsequent apoptosis

Clinical trials have revealed that the potential anticancer agent, 2-methoxyestradiol (2ME2) has limitations due to its low bioavailability. Subsequently, 2ME2 derivatives including (8R,13S,14S,17S)-2-ethyl-13-methyl-7,8,9,11,12,13,14,15,16,17-decahydro-6H-cyclopenta[a]phenanthrane-3,17-diyl bis(sulphamate) (EMBS) have shown improved efficacies in inducing apoptosis. However, no conclusive data exist to explain the mode of action exerted by these drugs. This study investigated the mode of action used by EMBS as a representative of the sulphamoylated 2ME2 derivatives. Hydrogen peroxide and superoxide production was quantified using dichlorofluorescein diacetate and hydroethidine. Cell proliferation and mitochondrial metabolism were investigated using crystal violet and Alamar Blue. Apoptosis was assessed using Annexin V-FITC while mitochondrial integrity was assessed using Mitocapture. Autophagy was visualised using LC3B II antibodies. The effects of EMBS on H2A phosphorylation and nuclei were visualised using phospho H2A antibody and 4',6-diamidino-2-phenylindole, dihydrochloride. Data showed that EMBS exposure leads to increased reactive oxygen species (ROS) production which is correlated with loss of cell proliferation, mitochondrial membrane damage, decreased metabolic activity, G2/M arrest, endoreduplication, DNA double stranded breaks, micronuclei and apoptosis induction. Treatment of EMBS-exposed cells with the ROS scavenger, N-acetyl cysteine, abrogated ROS production, cell cycle arrest and apoptosis implying an essential role for ROS production in EMBS signaling. The inhibition of c-Jun N-terminal kinase (JNK) activity also inhibited EMBS-induced apoptosis suggesting that EMBS triggers apoptosis via the JNK pathway. Lastly, evaluation of LC3IIB protein levels indicated that autophagy is not activated in EMBS-exposed cells. Our data shows that EMBS targets a pathway that leads to increased ROS production as an early event that culminates in G2/M arrest and apoptosis by means of JNK-signaling in cancer cells. This study suggests a novel oxidative stress-dependent mode of action for sulphamoylated derivatives.

Magnetic Resonance Imaging of Mitochondrial Dysfunction and Metabolic Activity, Accompanied by Overproduction of Superoxide

This study shows that a mitochondria-penetrating nitroxide probe (mito-TEMPO) allows detection of superoxide and visualization of mitochondrial dysfunction in living cells due to the effect of T1 shortening in MRI. Mitochondrial dysfunction was induced by treatment of cells with rotenone and 2-methoxyestradiol (2-ME/Rot). The MRI measurements were performed on 7T MRI. The 2-ME/Rot-treated cells were characterized by overproduction of superoxide, which was confirmed by a conventional dihydroethidium test. In the presence of mito-TEMPO, the intensity of MRI signal in 2-ME/Rot-treated cells was ∼30-40% higher, in comparison with that in untreated cells or culture media. In model (cell-free) systems, we observed that superoxide, but not hydrogen peroxide, increased the intensity of T1-weighted MRI signal of mito-TEMPO. Moreover, the superoxide restores the T1-weighted MRI contrast of mito-TEMPOH, a noncontrast (diamagnetic) analogue of mito-TEMPO. This was also confirmed by using EPR spectroscopy. The results demonstrate that superoxide radical is involved in the enhancement of T1-weighted MRI contrast in living cells, in the absence and presence of mito-TEMPO. This report gives a direction for discovering new opportunities for functional MRI, for detection of metabolic activity, accompanied by overproduction of superoxide, as well as by disturbance of the balance between superoxide and hydrogen peroxide, a very important approach to clarify the fine molecular mechanisms in the regulation of many pathologies. The visualization of mitochondrial activity in real-time can be crucial to clarify the molecular mechanism of the functional MRI in its commonly accepted definition, as a method for detection of neurovascular coupling.

DNA damage and S phase arrest induced by Ochratoxin A in human embryonic kidney cells (HEK 293)

Ochratoxin A (OTA) is a ubiquitous mycotoxin with potential nephrotoxic, hepatotoxic and immunotoxic effects. The mechanisms underlying the nephrotoxicity of OTA remain obscure. To investigate DNA damage and the changes of the cell cycle distribution induced by OTA, human embryonic kidney cells (HEK 293 cells) were incubated with various concentrations of OTA for 24h in vitro. The results indicated that OTA treatment led to the production of reactive oxygen species (ROS) and to a decrease of the mitochondrial membrane potential (ΔΨm). OTA-induced DNA damage in HEK 293 cells was evidenced by DNA comet tails formation and increased expression of γ-H2AX. In addition, OTA could induce cell cycle arrest at the S phase in HEK 293 cells. The expression of key cell cycle regulatory factors that were critical to the S phase, including cyclin A2, cyclin E1, and CDK2, were further detected. The expression of cyclin A2, cyclin E1, and CDK2 were significantly decreased by OTA treatment at both the mRNA and protein levels. The apoptosis of HEK 293 cells after OTA treatment was observed using Hoechst 33342 staining. The results confirmed that OTA did induce apoptosis in HEK 293 cells. In conclusion, our results provided new insights into the molecular mechanisms by which OTA might promote nephrotoxicity.

Endoplasmic reticulum stress signaling is involved in mitomycin C (MMC)-induced apoptosis in human fibroblasts via PERK pathway

Endoplasmic reticulum (ER) stress-mediated cell apoptosis has been implicated in various cell types, including fibroblasts. Previous studies have shown that mitomycin C (MMC)-induced apoptosis occurs in fibroblasts, but the effects of MMC on ER stress-mediated apoptosis in fibroblasts have not been examined. Here, MMC-induced apoptosis in human primary fibroblasts was investigated by exposing cells to a single dose of MMC for 5 minutes. Significant inhibition of cell proliferation and increased apoptosis were observed using a cell viability assay, Annexin V/propidium iodide double staining, cell cycle analysis, and TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling) staining. Upregulation of proapoptotic factors, including cleaved caspase-3 and poly ADP-ribose polymerase (PARP), was detected by Western blotting. MMC-induced apoptosis was correlated with elevation of 78-kDa glucose-regulated protein (GRP78) and C/EBP homologous protein (CHOP), which are hallmarks of ER stress. Three unfolded protein response (UPR) sensors (inositol-requiring enzyme 1, IRE1; activating transcription factor 6, ATF6; and PKR-like ER kinase, PERK) and their downstream signaling pathways were also activated. Knockdown of CHOP attenuated MMC-induced apoptosis by increasing the ratio of BCL-2/BAX and decreasing BIM expression, suggesting that ER stress is involved in MMC-induced fibroblast apoptosis. Interestingly, knockdown of PERK significantly decreased ER stress-mediated apoptosis by reducing the expression of CHOP, BIM and cleaved caspase-3. Reactive oxygen species (ROS) scavenging also decreased the expression of GRP78, phospho-PERK, CHOP, and BIM. These results demonstrate that MMC-induced apoptosis is triggered by ROS generation and PERK activation.

Oxidative DNA damage is involved in ochratoxin A-induced G2 arrest through ataxia telangiectasia-mutated (ATM) pathways in human gastric epithelium GES-1 cells in vitro

Ochratoxin A (OTA), one of the most abundant mycotoxin food contaminants, is classified as "possibly carcinogenic to humans." Our previous study showed that OTA could induce a G2 arrest in immortalized human gastric epithelium cells (GES-1). To explore the putative roles of oxidative DNA damage and the ataxia telangiectasia-mutated (ATM) pathways on the OTA-induced G2 arrest, the current study systematically evaluated the roles of reactive oxygen species (ROS) production, DNA damage, and ATM-dependent pathway activation on the OTA-induced G2 phase arrest in GES-1 cells. The results showed that OTA exposure elevated intracellular ROS production, which directly induced DNA damage and increased the levels of 8-OHdG and DNA double-strand breaks (DSBs). In addition, it was found that OTA treatment induced the phosphorylation of the ATM protein, as well as its downstream molecules Chk2 and p53, in response to DNA DSBs. Inhibition of ATM by the pharmacological inhibitor caffeine or siRNA effectively prevented the activation of ATM-dependent pathways and rescued the G2 arrest elicited by OTA. Finally, pretreatment with the antioxidant N-acetyl-L-cysteine (NAC) reduced the OTA-induced DNA DSBs, ATM phosphorylation, and G2 arrest. In conclusion, the results of this study suggested that OTA-induced oxidative DNA damage triggered the ATM-dependent pathways, which ultimately elicited a G2 arrest in GES-1 cells.

SUTAF, a novel β-methoxyacrylate derivative, promotes neurite outgrowth with extracellular signal-regulated kinase and c-jun N-terminal kinase activation

β-Methoxyacrylate antibiotics are well known to inhibit the fungal and yeast mitochondrial respiratory chain. In addition, β-methoxyacrylates are reported to suppress the proliferation of mammalian cancer cells. Differentiation and cell-cycle arrest are closely related. The cell cycle of proliferating cells is suppressed before differentiation. In this study, we synthesized a β-methoxyacrylate analog and treated neuronal differential model cells with it. We then estimated β-methoxyacrylate's neurotrophic effect by inhibiting cell proliferation so as to orient neuronal differentiation. SUTAF-027-a novel β-methoxyacrylate derivative, arrested the cell cycle and thereby suppressed the proliferation of PC12 rat pheochromocytoma cells and mouse neuroblastoma Neuro2a cells at very low treatment doses, as low as 1nM. However, a single SUTAF-027 treatment did not affect neuritogenesis. Surprisingly, however, co-treatment of SUTAF-027 and nerve growth factor (NGF) significantly augmented the NGF-induced neurite outgrowth of PC12. On the other hand, a single treatment of 1nM SUTAF-027 induced neurite outgrowth in Neuro2a cells. Further signal transduction mechanism studies revealed that SUTAF-027 induced the phosphorylation of extracellular signal-regulated kinase (ERK) and slight phosphorylation of c-jun N-terminal kinase (JNK). Moreover, inhibition of ERK and JNK blocked SUTAF-027-augmented neurite outgrowth. These results suggested that the novel β-methoxyacrylate analog SUTAF-027 augmented neurite outgrowth by arresting the cell cycle and activating the ERK and JNK pathways.

Developmental regulation of decidual cell polyploidy at the site of implantation

Polyploidy has been reported in several animal cells, as well as within humans; however the mechanism of developmental regulation of this process remains poorly understood. Polyploidy occurs in normal biologic processes as well as in pathologic states. Decidual polyploid cells are terminally differentiated cells with a critical role in continued uterine development during embryo implantation and growth. Here we review the mechanisms involved in polyploidy cell formation in normal developmental processes, with focus on known regulatory aspects in decidual cells.

Ochratoxin A induces oxidative DNA damage and G1 phase arrest in human peripheral blood mononuclear cells in vitro

Ochratoxin A is one of the most abundant food-contaminating mycotoxins worldwide, and its immunosuppressive effects in human caused more and more concern in biomedical field. In the present study, the toxicity of OTA on human peripheral blood mononuclear cells (hPBMC) was explored by analyzing the involvement of oxidative pathway. It was found that OTA treatment led to the release of reactive oxygen species (ROS) and the increase of 8-hydroxydeoxyguanosine (8-OHdG), an important biomarker of oxidative DNA stress. Moreover, we found that OTA treatment induced DNA strand breaks in hPBMC as evidenced by DNA comet tails formation and increased γ-H2AX expression. In addition, OTA could induce cell cycle arrest at G1 phase by down-regulating the expression of CDK4 and cyclinD1 protein, as well as apoptosis in hPBMC in vitro. Pre-treatment of hPBMC with antioxidant, N-acetyl-L-cysteine (NAC), could reduce OTA-induced ROS release and DNA damage, thus confirming the involvement of oxidative DNA damage in the OTA genotoxicity in hPBMC. NAC pre-treatment could also significantly prevent OTA-induced down-regulation of CDK4 and cyclinD1 expression in hPBMC. All the results demonstrated the involvement of oxidative pathway in OTA mediated cytotoxicity in human immune cells, which including the ROS accumulation-oxidative DNA damage-G1 arrest and apoptosis. Our results provide new insights into the molecular mechanisms by which OTA might promote immunotoxicity.

Decidual cell polyploidization necessitates mitochondrial activity

Cellular polyploidy has been widely reported in nature, yet its developmental mechanism and function remain poorly understood. In the present study, to better define the aspects of decidual cell polyploidy, we isolated pure polyploid and non-polyploid decidual cell populations from the in vivo decidual bed. Three independent RNA pools prepared for each population were then subjected to the Affymetrix gene chip analysis for the whole mouse genome transcripts. Our data revealed up-regulation of 1015 genes and down-regulation of 1207 genes in the polyploid populations, as compared to the non-polyploid group. Comparative RT-PCR and in situ hybridization results indeed confirmed differential expressional regulation of several genes between the two populations. Based on functional enrichment analyses, up-regulated polyploidy genes appeared to implicate several functions, which primarily include cell/nuclear division, ATP binding, metabolic process, and mitochondrial activity, whereas that of down-regulated genes primarily included apoptosis and immune processes. Further analyses of genes that are related to mitochondria and bi-nucleation showed differential and regional expression within the decidual bed, consistent with the pattern of polyploidy. Consistently, studies revealed a marked induction of mitochondrial mass and ATP production in polyploid cells. The inhibition of mitochondrial activity by various pharmacological inhibitors, as well as by gene-specific targeting using siRNA-mediated technology showed a dramatic attenuation of polyploidy and bi-nucleation development during in vitro stromal cell decidualization, suggesting mitochondria play a major role in positive regulation of decidual cell polyploidization. Collectively, analyses of unique polyploidy markers and molecular signaling networks may be useful to further characterize functional aspects of decidual cell polyploidy at the site of implantation.

Role of STAT3/5 and Bcl-2/xL in 2-methoxyestradiol-induced endoreduplication of nasopharyngeal carcinoma cells

2-methoxyestradiol (2ME2), an endogenous metabolite of 17-β-estradiol, has been shown to induce apoptosis and cell cycle arrest in various tumor models. We have previously shown that 2ME2 induced endoreduplication in a well-differentiated nasopharyngeal carcinoma (NPC) HK-1 and a poorly differentiated C666-1 cell line. In the present study, we studied the survival factors involved in 2ME2-induced endoreduplicating NPC cells. In the HK-1 cells, knockdown of BcL-xL expression by siRNA resulted in the reduction of endoreduplication and an increase in the percentage of apoptosis. Further mechanistic study revealed that 2ME2 enhanced the expression of the phosphorylated form of STAT5 (p-STAT5-Y694), but not p-STAT3 (Y705) and p-STAT3 (S727), in the nucleus of HK-1 cells. Pre-treatment of cells with JAK/STAT inhibitor AG490 and STAT5 inhibitor resulted not only in the reduced expression of Bcl-xL, but also reduced the percentage of endoreduplicating cells. In contrast, 2ME2 enhanced the expression of p-STAT3 in the poorly differentiated C666-1 cells. Pharmacological inhibition of STAT3 or Bcl-2/xL resulted in a decrease in endoreduplication of C666-1 cells. Taken together, the expression of p-STAT5 and p-STAT3 was upregulated in 2ME2-induced endoreduplicating HK-1 and C666-1 cells, respectively. Combination of 2ME2 with Bcl-2/xL inhibitor is a novel strategy to reduce the formation of endoreduplicating cells during chemotherapeutic treatment of NPC. © 2011 Wiley Periodicals, Inc.

Involvement of reactive oxygen species in 2-methoxyestradiol-induced apoptosis in human neuroblastoma cells

Neuroblastoma is the most common extra-cranial solid tumor in children. Despite advances in the treatment of childhood cancer, outcomes for children with advanced-stage neuroblastoma remain poor. Here we reported that 2-methoxyestradiol (2-ME) inhibited the proliferation and induced apoptosis in human neuroblastoma SK-N-SH and SH-SY5Y cells. 2-ME treatment also resulted in the generation of ROS and the loss of mitochondrial membrane potential in SK-N-SH and SH-SY5Y, indicating that 2-ME-induced apoptosis is mediated by ROS. This is supported by the results that have shown that co-treatment with antioxidants, VC, L-GSH and MitoQ(10), decreased 2-ME-induced generation of ROS and the loss of the mitochondrial membrane potential, increased the Bcl-2/Bax ratio, decreased 2-ME-induced activation of caspase-9 and caspase-3 and the up-regulation of apoptosis-inducing factor (AIF), and prevented 2-ME-induced apoptosis in SK-N-SH and SH-SY5Y cells. These results suggested that oxidative stress plays an important role in 2-ME-induced apoptotic death of human neuroblastoma cells.

Different effects of epidermal growth factor on smooth muscle cells derived from human myometrium and from leiomyoma

OBJECTIVE

To determine different effects of epidermal growth factor (EGF) on cultured smooth muscle cells (SMCs) derived from human myometrium and leiomyoma.

DESIGN

EGF effects on DNA synthesis and intracellular signal transduction were studied in cultured SMCs from leiomyoma and its matched myometrium.

SETTING

Research laboratories.

PATIENT(S)

Patients 35-50 years old with uterine leiomyomas.

INTERVENTION(S)

Hysterectomy.

MAIN OUTCOME MEASURE(S)

Signal transduction from EGF receptor.

RESULT(S)

As analyzed by laser scanning cytometry (LSC), EGF treatment stimulated DNA synthesis and induced polyploidization of leiomyomal, but not myometrial, SMCs. EGF stimulation was inhibited by AG1478, an EGF receptor (EGFR) inhibitor and PD98059, a mitogen-activated protein kinase (MAPK) kinase (MEK) inhibitor. Both leiomyomal and myometrial SMCs had similar expression levels of EGFR, but EGF treatment induced transient phosphorylation activation of EGFR and Akt in leiomyomal SMCs. Consequently, EGF triggered transient phosphorylation activation of p44/42 MAPK in leiomyomal SMCs, followed by down-regulation of p27. In myometrial SMCs, however, EGF induced sustained activation of EGFR, Akt, and p44/42 MAPK with up-regulation of p27.

CONCLUSION(S)

EGF stimulates DNA synthesis and polyploidization in leiomyomal SMCs through transient activation of the EGFR-MAPK pathway. Given that polyploidization plays a role in tumorigenesis, our results shed new light on the pathogenesis of human uterine leiomyoma.

Mechanisms of estrogens' dose-dependent neuroprotective and neurodamaging effects in experimental models of cerebral ischemia

Ever since the hypothesis was put forward that estrogens could protect against cerebral ischemia, numerous studies have investigated the mechanisms of their effects. Despite initial studies showing ameliorating effects, later trials in both humans and animals have yielded contrasting results regarding the fundamental issue of whether estrogens are neuroprotective or neurodamaging. Therefore, investigations of the possible mechanisms of estrogen actions in brain ischemia have been difficult to assess. A recently published systematic review from our laboratory indicates that the dichotomy in experimental rat studies may be caused by the use of insufficiently validated estrogen administration methods resulting in serum hormone concentrations far from those intended, and that physiological estrogen concentrations are neuroprotective while supraphysiological concentrations augment the damage from cerebral ischemia. This evidence offers a new perspective on the mechanisms of estrogens’ actions in cerebral ischemia, and also has a direct bearing on the hormone replacement therapy debate. Estrogens affect their target organs by several different pathways and receptors, and the mechanisms proposed for their effects on stroke probably prevail in different concentration ranges. In the current article, previously suggested neuroprotective and neurodamaging mechanisms are reviewed in a hormone concentration perspective in an effort to provide a mechanistic framework for the dose-dependent paradoxical effects of estrogens in stroke. It is concluded that five protective mechanisms, namely decreased apoptosis, growth factor regulation, vascular modulation, indirect antioxidant properties and decreased inflammation, and the proposed damaging mechanism of increased inflammation, are currently supported by experiments performed in optimal biological settings.

Thioredoxin protects fetal type II epithelial cells from hyperoxia-induced injury

Oxygen toxicity is known to be one of the major contributors to bronchopulmonary dysplasia, a chronic lung disease in premature infants. Thioredoxin (Trx) is an antioxidant that prevents oxidative stress-induced cell death, suggesting a potential therapeutic role in bronchopulmonary dysplasia. The aim of this study was to determine the role of Trx in the pathogenesis of hyperoxia-induced alveolar epithelial cell injury. Alveolar type II epithelial cells from fetal rat lung were exposed to hyperoxia in vitro in the presence or absence of recombinant human Trx (rhTrx 2 µg/ml). Cell viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Apoptosis and levels of reactive oxygen species (ROS) were measured by flow cytometry. Activation of mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase-Akt (PI3K-Akt) pathways were detected by Western blotting. We also investigated the effects of rhTrx on the following antioxidants (superoxide dismutase, catalase, and glutathione peroxidase). Trx significantly reduced hyperoxia-induced cell death and increased cell viability. In addition, ROS generation in type II cells was inhibited by rhTrx under hyperoxic conditions. We demonstrated that rhTrx protected type II cells against hyperoxic injury via sustaining the extracellular signal regulated kinase and PI3K activation, and decreasing of c-Jun N-terminal protein kinase and p38 activation. The results also showed manganese superoxide dismutase and glutathione peroxidase activities were increased by rhTrx in type II cells exposed to hyperoxia.Taken together, these results demonstrate that rhTrx administration markedly attenuates hyperoxia-induced type II cell injury through reduction of ROS generation, elevation of antioxidant activities and regulation of both MAPK and PI3K-Akt signaling pathways.

4-oxo-N-(4-hydroxyphenyl)retinamide: two independent ways to kill cancer cells

Background

The retinoid 4-oxo-N-(4-hydroxyphenyl)retinamide (4-oxo-4-HPR) is a polar metabolite of fenretinide (4-HPR) very effective in killing cancer cells of different histotypes, able to inhibit 4-HPR-resistant cell growth and to act synergistically in combination with the parent drug. Unlike 4-HPR and other retinoids, 4-oxo-4-HPR inhibits tubulin polymerization, leading to multipolar spindle formation and mitotic arrest. Here we investigated whether 4-oxo-4-HPR, like 4-HPR, triggered cell death also via reactive oxygen species (ROS) generation and whether its antimicrotubule activity was related to a ROS-dependent mechanism in ovarian (A2780), breast (T47D), cervical (HeLa) and neuroblastoma (SK-N-BE) cancer cell lines.

Methodology/Principal Findings

We provided evidence that 4-oxo-4-HPR, besides acting as an antimicrotubule agent, induced apoptosis through a signaling cascade starting from ROS generation and involving endoplasmic reticulum (ER) stress response, Jun N-terminal Kinase (JNK) activation, and upregulation of the proapoptotic PLAcental Bone morphogenetic protein (PLAB). Through time-course analysis and inhibition of the ROS-related signaling pathway (upstream by vitamin C and downstream by PLAB silencing), we demonstrated that the antimitotic activity of 4-oxo-4-HPR was independent from the oxidative stress induced by the retinoid. In fact, ROS generation occurred earlier than mitotic arrest (within 30 minutes and 2 hours, respectively) and abrogation of the ROS-related signaling pathway did not prevent the 4-oxo-4-HPR-induced mitotic arrest.

Conclusions/Significance

These data indicate that 4-oxo-4-HPR anticancer activity is due to at least two independent mechanisms and provide an explanation of the ability of 4-oxo-4-HPR to be more potent than the parent drug and to be effective also in 4-HPR-resistant cell lines. In addition, the double mechanism of action could allow 4-oxo-4-HPR to efficiently target tumour and to eventually counteract the development of drug resistance.