Mechanisms of apoptosis

Targeted Therapy of Spinal Cord Injury: Inhibition of Apoptosis Is a Promising Therapeutic Strategy

Spinal cord injury (SCI) is a serious disabling central nervous system injury that can lead to motor, sensory, and autonomic dysfunction below the injury level. SCI can be divided into primary injury and secondary injury according to pathological process. Primary injury is mostly irreversible, while secondary injury is a dynamic regulatory process. Apoptosis is an important pathological event of secondary injury and has a significant effect on the recovery of nerve function after SCI. Nerve cell death can further aggravate the microenvironment of the injured site, leading to neurological dysfunction and thus affect the clinical outcome of patients. Therefore, apoptosis plays a crucial role in the pathological progression of secondary SCI, while inhibiting apoptosis may be a promising therapeutic strategy for SCI. This review will summarize and explore the factors that lead to cell death after SCI, the influence of cross talk between signaling pathways and pathways involved in apoptosis and discuss the influence of apoptosis on SCI, and the therapeutic significance of targeting apoptosis on SCI. This review helps us to understand the role of apoptosis in secondary SCI and provides a theoretical basis for the treatment of SCI based on apoptosis.

Function and mechanism of action of the TRPV1 channel in the development of triple-negative breast cancer

Transient receptor potential channel subfamily vanilloid 1 (TRPV1) is a member of the transient receptor potential family of nonselective cationic transmembrane channel proteins that are involved in the regulation of calcium homeostasis. It is expressed in various tumor types and has been implicated in the regulation of cancer growth, metastasis, apoptosis, and cancer-related pain. TRPV1 is highly expressed in triple-negative breast cancer (TNBC), and both its agonists and antagonists may exert anti-cancer effects. In this review, we provide an overview of the effect of TRPV1 on TNBC development and its influence on immunotherapy in an attempt to facilitate the development of future treatment strategies.

2'-Fucosyllactose Ameliorates Oxidative Stress Damage in d-Galactose-Induced Aging Mice by Regulating Gut Microbiota and AMPK/SIRT1/FOXO1 Pathway

The imbalance of reactive oxygen species is the main cause in aging, accompanied by oxidative stress. As the most abundant in human milk oligosaccharides (HMOs), 2′-Fucosyllactose (2′-FL) has been confirmed to have great properties in immunity regulation and anti-inflammatory. The research on 2′-FL is focused on infants currently, while there is no related report of 2′-FL for the elderly. A d-galactose-induced accelerated aging model was established to explore the protective effect of 2′-FL on the intestines and brain in mice. In this study, 2′-FL significantly reduced oxidative stress damage and inflammation in the intestines of aging mice, potentially by regulating the sirtuin1 (SIRT1)-related and nuclear factor E2-related factor 2 (Nrf2) pathways. In addition, 2′-FL significantly improved the gut mucosal barrier function and increased the content of short-chain fatty acids (SCFAs) in the intestine. The gut microbiota analysis indicated that 2′-FL mainly increased the abundance of probiotics like Akkermansia in aging mice. Moreover, 2′-FL significantly inhibited apoptosis in the brains of aging mice, also increasing the expression of SIRT1. These findings provided a basis for learning the benefits of 2′-FL in the aging process.

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...

High-Carbohydrate Diet Alleviates the Oxidative Stress, Inflammation and Apoptosis of Megalobrama amblycephala Following Dietary Exposure to Silver Nanoparticles

A 12-week feeding trial was performed to evaluate the effects of high-carbohydrate diet on oxidative stress, inflammation and apoptosis induced by silver nanoparticles (Ag-NPs) in M. amblycephala. Fish (20.12 ± 0.85 g) were randomly fed four diets (one control diet (C, 30% carbohydrate), one control diet supplemented with 100 mg kg⁻¹ Ag-NPs (CS), one high-carbohydrate diet (HC, 45% carbohydrate) and one HC diet supplemented with 100 mg kg⁻¹ Ag-NPs (HCS)). The results indicated that weight gain rate (WGR), specific growth rate (SGR), antioxidant enzyme (SOD and CAT) activities and expression of Trx, Cu/Zn-SOD, Mn-SOD, CAT and GPx1 of fish fed CS diet were all remarkably lower than those of other groups, whereas the opposite was true for plasma IL 1β and IL 6 levels, liver ROS contents, hepatocytes apoptotic rate, AMP/ATP ratio, AMPKα, P 53 and caspase 3 protein contents and mRNA levels of AMPKα 1, AMPKα 2, TXNIP, NF-κB, TNFα, IL 1β, IL 6, P 53, Bax and caspase 3. However, high-carbohydrate diet remarkably increased WGR, SGR, liver SOD and CAT activities, AMPKα protein content and mRNA levels of antioxidant genes (Cu/Zn-SOD, Mn-SOD, CAT and GPx1), anti-inflammatory cytokines (IL 10) and anti-apoptotic genes (Bcl 2) of fish facing Ag-NPs compared with the CS group, while the opposite was true for liver ROS contents, hepatocytes apoptotic rate, P 53 and caspase 3 protein contents, as well as mRNA levels of TXNIP, NF-κB, TNFα, IL 1β, IL 6, P 53, Bax and caspase 3. Overall, high-carbohydrate diet could attenuate Ag-NPs-induced hepatic oxidative stress, inflammation and apoptosis of M. amblycephala through AMPK activation.

Orostachys japonicus exerts antipancreatic cancer activity through induction of apoptosis and cell cycle arrest in PANC-1 cells

Targeted therapy at the molecular level is important for pancreatic cancer treatment. This study looked over the anticancer activity of Orostachys japonicus in a human pancreatic cancer cell line, PANC-1. An ethyl acetate fraction containing quercetin, kaempferol, and flavonol glycosides from O. japonicus (OJE) exhibited significant anticancer activity against the PANC-1. OJE activated caspase-3, caspase-8, and caspase-9, leading to the induction of both intrinsic and extrinsic apoptosis pathways. It also inhibited cyclin D1, cyclin B1, and cyclin-dependent kinase 4, representing cell cycle arrest at both G1/S and G2/M phases. In addition, OJE phosphorylated MAPKs such as p38, JNK, and ERK, which are important upstream signaling factors in apoptosis and arrest of cell cycle inducing system. In conclusion, OJE effectively exerted antipancreatic cancer activity via induction of apoptosis directed by both intrinsic and extrinsic pathways and arrest of cell cycle regulated at both G1/S and G2/M stages, which is activated by MAPKs, p38, JNK, and ERK.

Effects of Fludioxonil on the Cell Growth and Apoptosis in T and B Lymphocytes

Fludioxonil is fungicide used in agriculture, which is present in fruits and vegetables. In this study, the effects of fludioxonil on human immune cell viability, apoptosis, cell cycle arrest, and mitochondrial membrane potential were examined in human immune cells, such as Jurkat T cells and Ramos B cells. To examine the cell viability, Jurkat T cells and Ramos B cells were treated with fludioxonil (10⁻⁹–10⁻⁵ M) for 24 h and 48 h. Water soluble tetrazolium salt assay showed that fludioxonil decreased Jurkat T cell and Ramos B cell viability. Jurkat T cell viability decreased at 24 and 48 h, but Ramos B cell viability decreased only at 48 h. JC-1 dye revealed decreased mitochondrial membrane potential in fludioxonil-treated Jurkat T cells and Ramos B cells. To evaluate apoptosis, annexin-V conjugated FITC, AF488, and propidium iodide (PI) were used and to evaluate cell cycle arrest PI was used. Apoptosis and cell cycle arrest were induced by fludioxonil (10⁻⁷–10⁻⁵ M) in the Jurkat T cells at 24 and 48 h and Ramos B cells at 48 h. Moreover, the protein levels of pro-apoptotic proteins, such as p53, BAX, and cleaved caspase 3, were increased and anti-apoptotic protein Bcl-2 was decreased by fludioxonil. Expression of the Fas receptor related to the extrinsic apoptosis pathway was increased by fludioxonil. Additionally, cyclin D1 and cyclin E1 were decreased by fludioxonil. In the present study, fludioxonil induced immunotoxicity in human T cells and B cells through apoptosis and cell cycle arrest. Therefore, the present study suggests that fludioxonil induces the cellular toxicity in immune cells.

Cordycepin induces apoptosis in SGC‑7901 cells through mitochondrial extrinsic phosphorylation of PI3K/Akt by generating ROS

Medicinal plants are affluent sources of several effectual natural drugs. Among them cordycepin which is extracted from Cordyceps militaris is a hopeful chemotherapy agent due to its extensive anti-inflammatory, anti-proliferative, antioxidant, and antitumor characteristics. This study investigated the efficacy of cordycepin in the context of human gastric cancer SGC‑7901 and searched for the cell death procedure. Cordycepin incorporates mitochondrial-mediated apoptosis in SGC‑7901 cells with the help of regulating mitochondrial extrinsic pathways by inhibition of A3AR and drive activation of DR3, which promote the activation of PI3K/Akt protein expression as well as collapse of mitochondrial membrane potential (MMP). In addition, phosphorylation of PI3K/Akt and DNA damage by cordycepin induced the production of reactive oxygen species (ROS), and mediates SGC‑7901 cell cycle cessation at S phase. Collectively, this study suggests that cordycepin might be effective as a modern chemotherapy drug for gastric cancer.

Cytotoxicity and apoptosis induced by mixed mycotoxins (T-2 and HT-2 toxin) on primary hepatocytes of broilers in vitro

T-2 and HT-2 (T-2/HT-2) induced cytotoxicity and apoptosis in hepatocytes from broilers. In this study, hepatocytes treated with T-2/HT-2 were analyzed for cytotoxic effects and apoptosis and for the associated mechanisms. To assay cytotoxicity, we used the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) viability assay, hematoxylin-eosin staining and aspartase transaminase and alanine transaminase (ALT/AST) activities. We evaluated apoptosis by fluorescence microscopy using the Terminal transferase nick-end labeling (TUNEL) assay. The apoptotic ratio and the apoptotic stage of the hepatocytes were next assessed with fluorescently labeled (FITC) Annexin V and propidium iodide (PI) staining. Finally, expression levels of apoptosis-related mRNAs were assessed by real-time PCR and those of apoptosis-related proteins by western blotting. We found that cells treated with T-2/HT-2 showed, in a dose dependent manner, significantly lower cell viabilities (P < 0.05) and markedly increased intercellular spaces, dead cells and ALT/AST activities. T-2/HT-2 treatment also significantly increased the number of apoptotic cells and the apoptotic ratio (P < 0.05). T-2/HT-2 induced early stage apoptosis of the hepatocytes and levels of apoptosis-related mRNAs and proteins changed in a manner implicating them in the apoptotic process. These changes occurred from 0 to 24 h of T-2/HT-2 exposure. Expression of bax and caspase-7 mRNAs was significantly upregulated, in a time-dependent manner, during this period (P < 0.05). Levels of mRNAs for caspase-3 and caspase-9 were increased from 0 to 12 h (P < 0.05) and then decreased after 12 h (P < 0.05). There were no significant effects on expression of bcl-2 mRNA (P > 0.05). Expression of all apoptosis-related proteins examined, except for bcl-2, was significantly increased from 0 to 24 h in a time-dependent manner (P < 0.05). Overall, T-2/HT-2 induced cytotoxicity and apoptosis in hepatocytes. The resulting changes in mRNA and protein expression were shown that several apoptosis-related proteins were involved in the liver toxicity of these agents.

Apoptosis induced by sonodynamic therapy in human osteosarcoma cells in vitro

The aim of the present study was to investigate the potential effect of hematoporphyrin monomethyl ether-sonodynamic therapy (HMME-SDT) on MG-63 osteosarcoma cells. The HMME concentration was kept constant at 20 µg/ml and the MG-63 osteosarcoma cell line was exposed to ultrasound with an intensity of 1.0 W/cm2 for 30 sec. Cell cytotoxicity was quantified using an MTT assay 6 h after HMME-SDT. The intracellular localization of HMME was imaged using inverted confocal laser scanning microscopy. Apoptosis was investigated using flow cytometry with Annexin V-fluorescein isothiocyanate and propidium iodine staining. The cytotoxicity of HMME-mediated sonodynamic action on MG-63 cells was significantly higher than that of other treatments, including ultrasound alone, HMME alone and sham treatment. Flow cytometry demonstrated that HMME‑SDT action markedly enhanced the apoptotic rate of MG-63 cells. The mechanisms of apoptosis were analyzed by measuring the protein expression of poly ADP-ribose polymerase (PARP), cleaved PARP, procaspase-3, cleaved caspase-3 and cleaved caspase-9. The data demonstrated that HMME-SDT action markedly induced the apoptosis of MG-63 cells.

Toxicity induced by F. poae-contaminated feed and the protective effect of Montmorillonite supplementation in broilers

The T-2 and HT-2 toxins, the main metabolites of Fusarium poae, induce toxicity in broilers and accumulate in tissues. Consequently, during the breeding process of broilers, diets are frequently supplemented with physical adsorbents to protect birds against the toxicity induced by mycotoxins. In the present research, T-2 and HT-2 were produced in maize inoculated with F. poae. Mont, the strongest adsorbent based on in vitro adsorption ratios, was added to the contaminated diet. One-day-old chickens were randomly and equally divided into the following four groups: control diet group, Mont supplemented diet group, contaminated diet group and detoxification diet group. The experiment lasted for 42 days. Compared to the control group, the contaminated group showed significant decrease in body weight, feed intake and TP (P < 0.05), and marked increase in FCR, ALP, AST and ALT activity, T-2/HT-2 residues in the tissues and the relative expressions of apoptosis-related mRNAs (P < 0.05). Mont supplementation provided protection for the treated broilers in terms of performance, blood biochemistry, hepatic function, T-2/HT-2 residue of tissues and apoptosis. Therefore, Mont may be suitable as a detoxification agent for T-2/HT-2 in feed for broilers.

Capilliposide Isolated from Lysimachia capillipes Hemsl. Induces ROS Generation, Cell Cycle Arrest, and Apoptosis in Human Nonsmall Cell Lung Cancer Cell Lines

Several data has reported that capilliposide, extracted from a traditional Chinese medicine, Lysimachia capillipes Hemsl. (LC) could exhibit inhibitory effect on cell proliferation in various cancers. The current study investigated the antitumor efficacy of Capilliposide and elucidated its potential molecular mechanism involved in vivo and vitro. Our results indicated that LC capilliposide inhibited proliferation of lung cancer cells in a dose-dependent manner. LC capilliposide induced cell cycle arrest at the S stage and enhanced apoptosis in NSCLC cells. Treatment with LC capilliposide increased the intracellular level of ROS, which activated the mitochondrial apoptotic pathway. Blockage of ROS by NAC highly reversed the effect of LC capilliposide on apoptosis. Xenograft tumor growth was significantly lower in the LC-treated group compared with the untreated control group (P < 0.05). The results also show that LC treatment does not produce any overt signs of acute toxicity in vivo. These findings demonstrate that LC capilliposide could exert an anti-tumor effect on NSCLC through mitochondrial-mediated apoptotic pathway and the activation of ROS is involved.

Posttraumatic Chondrocyte Apoptosis in the Murine Xiphoid

OBJECTIVE

To demonstrate posttraumatic chondrocyte apoptosis in the murine xiphoid after a crush-type injury and to ultimately determine the pathway (i.e., intrinsic or extrinsic) by which chondrocytes undergo apoptosis in response to mechanical injury.

DESIGN

The xiphoids of adult female wild-type mice were injured with the use of a modified Kelly clamp. Postinjury xiphoid cartilage was analyzed via 3 well-described independent means of assessing apoptosis in chondrocytes: hematoxylin and eosin staining, terminal deoxynucleotidyl transferase dUTP nick end labeling assay, and activated caspase-3 staining.

RESULTS

Injured specimens contained many chondrocytes with evidence of apoptosis, which is characterized by cell shrinkage, chromatin condensation, nuclear fragmentation, and the liberation of apoptotic bodies. There was a statistically significant increase in the number of chondrocytes undergoing apoptosis in the injured specimens as compared with the uninjured specimens.

CONCLUSIONS

Chondrocytes can be stimulated to undergo apoptosis as a result of mechanical injury. These experiments involving predominantly cartilaginous murine xiphoid in vivo establish a baseline for future investigations that employ the genetic and therapeutic modulation of chondrocyte apoptosis in response to mechanical injury.

The induction of the apoptosis of cancer cell by sonodynamic therapy: a review

Ultrasound can be used not only in the examination, but also in the therapy, especially in the therapy of cancer, which has got effect in the treatment. Sonodynamic therapy is an experimental cancer therapy which uses ultrasound to enhance the cytotoxic effects of drugs known as sonosensitizers. It has been tested in vitro and in vivo. The ultrasound could penetrate the tissue and cell under some of conditions which directly changes the cell membranes permeability, thereby allowing the delivery of exogenous molecules into the cells in some degree. Ultrasound could inhibit the proliferation or induce the apoptosis of the cancer cell in vitro or in vivo. Recent research indicated low frequency and low intensity ultrasound could induce cells apoptosis, and which could be strengthened by sonodynamic sensitivities, microbubbles, chemotherapeutic drugs and so on. Most kinds of ultrasound suppressed the proliferation of cancer cell through inducing the apoptosis of cancer cell. The mechanism of apoptosis is not clear. In this review, we will focus on and discuss the mechanisms of the induction of the apoptosis of cancer cell by ultrasound.

Bortezomib is cytotoxic to the human growth plate and permanently impairs bone growth in young mice

Bortezomib, a novel proteasome inhibitor approved for the treatment of cancer in adults, has recently been introduced in pediatric clinical trials. Any tissue-specific side effects on bone development have to our knowledge not yet been explored. To address this, we experimentally studied the effects of bortezomib in vivo in young mice and in vitro in organ cultures of rat metatarsal bones and human growth plate cartilage, as well as in a rat chondrocytic cell line. We found that bortezomib while efficiently blocking the ubiquitin/proteasome system (UPS) caused significant growth impairment in mice, by increasing resting/stem-like chondrocyte apoptosis. Our data support a local action of bortezomib, directly targeting growth plate chondrocytes leading to decreased bone growth since no suppression of serum levels of insulin-like growth factor-I (IGF-I) was observed. A local effect of bortezomib was confirmed in cultured rat metatarsal bones where bortezomib efficiently caused growth retardation in a dose dependent and irreversible manner, an effect linked to increased chondrocyte apoptosis, mainly of resting/stem-like chondrocytes. The cytotoxicity of bortezomib was also evaluated in a unique model of cultured human growth plate cartilage, which was found to be highly sensitive to bortezomib. Mechanistic studies of apoptotic pathways indicated that bortezomib induced activation of p53 and Bax, as well as cleavage of caspases and poly-ADP-ribose polymerase (PARP) in exposed chondrocytes. Our observations, confirmed in vivo and in vitro, suggest that bone growth could potentially be suppressed in children treated with bortezomib. We therefore propose that longitudinal bone growth should be closely monitored in ongoing clinical pediatric trials of this promising anti-cancer drug.

Progallin A isolated from the acetic ether part of the leaves of Phyllanthus emblica L. induces apoptosis of human hepatocellular carcinoma BEL-7404 cells by up-regulation of Bax expression and down-regulation of Bcl-2 expression

AIM OF THE STUDY

This study was aimed to investigate the effects of Progallin A isolated from the acetic ether part of the leaves of Phyllanthus emblica L. on apoptosis in human hepatocellular carcinoma BEL-7404 cells and its possible mechanisms, and to measure the immune toxicity of Progallin A in vitro.

MATERIALS AND METHODS

Progallin A was isolated from the acetic ether part of the leaves of Phyllanthus emblica L. with column chromatography. The proliferation of spleen lymphocytes and the viability of BEL-7404 cells were assessed with MTT assay. Inverted microscope, light microscope and fluorescence microscope were utilized to observe the morphological changes of BEL-7404 cells respectively. AnnexinV/PI double labeling and TUNEL assay were used to detect early apoptosis and DNA fragmentations of BEL-7404 cells respectively. In addition, cell cycle distribution was analyzed by using flow cytometry (FCM). Bax and Bcl-2 protein levels were determined by immunofluorescence staining and western blot respectively.

RESULTS

The results showed that Progallin A had low immune toxicity and the proliferation of BEL-7404 cells was strongly inhibited by Progallin A in a time- and dose-dependent manner and that the characteristics of apoptosis of BEL-7404 cells were observed. The results also showed that apoptosis rates and the number of apoptotic cells significantly increased with prolongation of the action time. The results of flow cytometry (FCM) indicated that Progallin A induced significant G1/M and G2/M arrest of BEL-7404 cells. Immunofluorescence staining and western blot showed that the expression of Bax was found to be noticeably up-regulated and the expression of Bcl-2 was down-regulated significantly.

CONCLUSIONS

These results indicate that Progallin A has low immune toxicity in vitro and induces apoptosis of human hepatocellular carcinoma BEL-7404 cells which is related to the G1/M and G2/M arrest, and it exerts its apoptotic effect by up-regulation of Bax expression and down-regulation of Bcl-2 expression.

Deregulation of apoptosis mediators' p53 and bcl2 in lung tissue of COPD patients

Abnormal apoptotic events in chronic obstructive pulmonary disease (COPD) subvert cellular homeostasis and may play a primary role in its pathogenesis. However, studies in human subjects are limited.

p53 and bcl2 protein expression was measured by western blot on lung tissue specimens from 43 subjects (23 COPD smokers and 20 non-COPD smokers), using beta-actin as internal control. Additionally, p53 and bcl2 expression patterns were evaluated by immunohistochemistry in formalin-fixed, paraffin-embedded lung tissue sections from the same individuals.

Western blot analysis showed statistically significant increased p53 protein levels in COPD smokers in comparison with non-COPD smokers (p = 0.038), while bcl2 protein levels were not statistically different between the two groups. Lung immunohistochemistry showed increased ratio of positive p53-stained type II pneumocytes/total type II pneumocytes in COPD smokers compared to non-COPD smokers (p = 0.01), whereas the p53 staining ratio in alveolar macrophages and in lymphocyte-like cells did not differ statistically between the two groups. On the other hand, bcl2 expression did not differ between the two groups in all three cell types.

The increased expression of pro-apoptotic p53 in type II pneumocytes of COPD patients not counterbalanced by the anti-apoptotic bcl2 could reflect increased apoptosis in the alveolar epithelium of COPD patients. Our results confirm previous experiments and support the hypothesis of a disturbance in the balance between the pro- and anti-apoptotic mediators in COPD.

In situ localization of apoptosis using TUNEL

Apoptosis is an important process both in normal biology and in various pathologies and disease states. Apoptosis in tissue or cells can be detected in a number of ways. In tissue sections, electron microscopy can identify apoptosis by cellular and nuclear morphology, and in live cells, changes in the membrane and membrane permeability allow apoptosis and necrosis to be observed. Histologically, apoptosis is best detected using the partial DNA degradation that is present in apoptotic cell nuclei. Terminal transferase-mediated UTP nick end-labeling (TUNEL) has been used successfully for detection of DNA degradation in paraffin-embedded tissue sections and can be combined with immunohistochemistry if desired to allow more precise identification of apoptotic cells.

Modulation of anti-apoptotic and survival pathways by curcumin as a strategy to induce apoptosis in cancer cells

Apoptosis is a highly regulated mechanism by which cells undergo cell death in an active way. As one of the most challenging tasks concerning cancer is to induce apoptosis in malignant cells, researchers increasingly focus on natural products to modulate apoptotic signaling pathways. Curcumin, a natural compound isolated from the plant Curcuma longa, has chemopreventive properties, which are mainly due to its ability to arrest cell cycle and to induce apoptosis. This article reviews the main effects of curcumin on the different apoptotic signaling pathways involved in curcumin-induced apoptosis of cancer cells, including the intrinsic and extrinsic apoptosis pathways, the NF-kappaB-mediated pathway as well as the PI3K/Akt signaling pathway. This review also focuses on the sensitization of cells to TRAIL-induced apoptosis after curcumin treatment and shows that curcumin enhances the capacity to induce cell death of different chemotherapeutical drugs.

T-2 toxin-induced apoptosis involving Fas, p53, Bcl-xL, Bcl-2, Bax and caspase-3 signaling pathways in human chondrocytes

OBJECTIVE

To investigate the effects of T-2 toxin on expressions of Fas, p53, Bcl-xL, Bcl-2, Bax and caspase-3 on human chondrocytes.

METHODS

Human chondrocytes were treated with T-2 toxin (1-20 ng/ml) for 5 d. Fas, p53 and other apoptosis-related proteins such as Bax, Bcl-2, Bcl-xL, caspase-3 were determined by Western blot analysis and their mRNA expressions were determined by reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

Increases in Fas, p53 and the pro-apoptotic factor Bax protein and mRNA expressions and a decrease of the anti-apoptotic factor Bcl-xL were observed in a dose-dependent manner after exposures to 1-20 ng/ml T-2 toxin, while the expression of the anti-apoptotic factor Bcl-2 was unchanged. Meanwhile, T-2 toxin could also up-regulate the expressions of both pro-caspase-3 and caspase-3 in a dose-dependent manner.

CONCLUSION

These data suggest a possible underlying molecular mechanism for T-2 toxin to induce the apoptosis signaling pathway in human chondrocytes by regulation of apoptosis-related proteins.

Effects of a one-week treatment with acid gastric inhibitors on Helicobacter pylori-infected mice

OBJECTIVE

Antiacid drugs, including omeprazole and ranitidine, were prescribed to Helicobacter pylori-infected subjects in combination with antibiotics during eradication treatment. Several reports suggest that these drugs have additional pharmacological properties, such as antineutrophil, antiapoptotic and antioxidant characteristics. The aim of this work was to study the effects of acid suppressive medication treatment in the H. pylori infection experimental model, focusing on possible additional pharmacological properties.

MATERIAL AND METHODS

The ability of gastric acid suppression was assessed in pylorus-ligated animals. Gastric H. pylori colonization levels, myeloperoxidase (MPO) acitivity, macroscopic damage, Bax and Bcl-2 expression and DNA damage levels were assessed in C57BL/6-infected mice after treatment for one week with omeprazole (100 mg kg(-1)) or ranitidine (100 mg kg(-1)).

RESULTS

Omeprazole treatment increased bacteria colonization and MPO activity in mice stomachs. Both antiacid drugs efficiently improved macroscopic damage, although only omeprazole restored the expression of the antiapoptotic Bcl-2 protein in gastric mucosa of infected animals.

CONCLUSIONS

Some additional omeprazole-related properties, such as antineutrophil properties, were not observed in H. pylori-infected mice after one week of treatment, suggesting that this property is restricted to in vitro approaches. However, the antiapoptotic activity of omeprazole could be attributed to an ability to modify the protein expression of Bcl-2, decreased by H. pylori infection.

Switch to full-length of XAF1 mRNA expression in prostate cancer cells by the DNA methylation inhibitor

X-linked inhibitor of apoptosis protein (XIAP) suppresses apoptotic cell death by binding to caspases and inhibiting their functions, while the XIAP-associated factor1 (XAF1), a zinc finger protein, antagonizes XIAP activities, thereby promoting apoptosis. The aberrant silence of the XAF1 gene has recently been found in various types of cancer cells, which is suggested to be one of the potential mechanisms underlying survival advantages of malignant cells. In the present study, we investigated the XAF1 expression in prostate cancer cells. Compared with normal tissues where a full-length of XAF1 mRNA is predominant, LNCaP and DU145 prostate cancer cell lines only expressed a short form of XAF1 transcripts, whereas PC3 cells exhibited a complete silence of the XAF1 gene. Inhibition of DNA methylation led to a switch to the full length of XAF1 mRNA expression in LNCaP and DU145 cells. The down-regulation of XAF1 expression was also observed in 6/8 tumor samples derived from patients with prostate cancer. Our findings suggest that splicing alterations or downregulation of the XAF1 transcript may occur during the development of prostate cancers due to the aberrant DNA methylation. The alternative splicing of XAF1 mRNA leads to formation of a truncated XAF1 protein with 19 amino acid deletion in its zinc finger domain, which likely affects its functional interaction with XIAP, and consequently, contributes to the pathogenesis of prostate cancers by disrupting balance of the apoptosis machinery.

UVA-induced apoptosis studied by the new apo/necro-Comet-assay which distinguishes viable, apoptotic and necrotic cells

An adaptation of the Comet-assay was developed which enables the discrimination of viable, apoptotic and necrotic single cells by use of the common Annexin-V staining and a dye exclusion test on the cells already embedded in agarose gel on glass slides. Membrane integrity (Ethidium-Homodimer exclusion), cellular esterase activity (Calcein blue-AM) as well as translocation of phosphadidyl-serine (Annexin-V) were analysed using these stains. The advantage of the 'apo/necro-Comet-assay' is that the viability status of individual cells can be determined and correlated with the DNA fragmentation pattern (comet) formed by the same cells. Hence, DNA damage can be assessed and correlated with viable cells or cells undergoing early, mid- or late stage apoptosis or necrosis as identified by the staining pattern. The staining was verified using heat and etoposide-induced apoptosis. This technique, among others, was used to study whether apoptotic fragmentation interferes with repair kinetics measured with the comet assay following UVA exposure (doses up to 1,280 kJ/m(2)) in the cultured human keratinocytes (HaCaT). Therefore, a time course of apoptotic events (phosphatidyl translocation and TUNEL fragmentation) was established and correlated to the DNA fragmentation in the comet-assay. Apoptotic cells were detected more than 8 h later. The combined three-colour staining method with the comet assay showed that there was no significant interference of DNA repair by apoptotic fragmentation processes since DNA repair was almost completed before the onset of apoptotic fragmentation. The apo/necro-Comet-assay reduces the general problem of false-positive results in genotoxicity tests using the Comet-assay.

Curcumin induces human HT-29 colon adenocarcinoma cell apoptosis by activating p53 and regulating apoptosis-related protein expression

Curcumin, a major yellow pigment and active component of turmeric, has multiple anti-cancer properties. However, its molecular targets and mechanisms of action on human colon adenocarcinoma cells are unknown. In the present study, we examined the effects of curcumin on the proliferation of human colon adenocarcinoma HT-29 cells by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide method and confirmed the curcumin-induced apoptosis by morphology and DNA ladder formation. At the same time, p53, phospho-p53 (Ser15), and other apoptosis-related proteins such as Bax, Bcl-2, Bcl-xL, pro-caspase-3, and pro-caspase-9 were determined by Western blot analysis. The colon adenocarcinoma cells were treated with curcumin (0-75 microM) for 0-24 h. We observed that p53 was highly expressed in HT-29 cells and curcumin could up-regulate the serine phosphorylation of p53 in a time- and concentration-dependent manner. An increase in expression of the pro-apoptotic factor Bax and a decrease in expression of the anti-apoptotic factor Bcl-2 were also observed in a time-dependent manner after exposure of 50 microM curcumin, while the expression of the anti-apoptotic factor Bcl-xL was unchanged. Curcumin could also down-regulate the expression of pro-caspase-3 and pro-caspase-9 in a time-dependent manner. These data suggest a possible underlying molecular mechanism whereby curcumin could induce the apoptosis signaling pathway in human HT-29 colon adenocarcinoma cells by p53 activation and by the regulation of apoptosis-related proteins. This property of curcumin suggests that it could have a possible therapeutic potential in colon adenocarcinoma patients.

Apoptosis of hepatocytes caused by Punta Toro virus (Bunyaviridae: Phlebovirus) and its implication for Phlebovirus pathogenesis

Experimental infection of hamsters with Punta Toro virus (PTV) produces a disease with clinical and pathological similarities to the severe human hemorrhagic fever caused by Rift Valley fever virus (RVFV), thus providing an animal model for RVFV pathogenesis. In this model, hepatocytic apoptosis is the main pathological component of liver injuries that are responsible for severe hemorrhagic manifestations. To further elucidate whether viral replication in hepatocytes directly causes apoptosis, we studied the morphological and biochemical changes of apoptosis in HepG2 cells at different time points after PTV infection. Cellular viability began to decrease 12 hours after infection compared with controls. Caspases 3/7 were activated significantly at 48 and 72 hours after infection, and phosphatidylserine translocation and DNA fragmentation were also detected at 48 and 72 hours. Cell cycle analysis by flow cytometry showed that infected HepG2 cells were arrested at G(0)/G(1) phase. Furthermore, virus titer increased with apoptosis progression, suggesting that viral replication is necessary for the apoptotic process. These results indicate that PTV infection alone, without a secondary inflammatory cellular reaction, induces hepatocytic apoptosis and suggest that future therapeutics for RVFV hemorrhagic disease might target inhibition of cellular apoptotic pathways during the acute infection.

Human Immunodeficiency virus type 1 Nef potently induces apoptosis in primary human brain microvascular endothelial cells via the activation of caspases

The lentiviral protein Nef plays a major role in the pathogenesis of human immunodeficiency virus type I (HIV-1) infection. Although the exact mechanisms of its actions are not fully understood, Nef has been shown to be essential for the maintenance of high-titer viral replication and disease pathogenesis in in vivo models of simian immunodeficiency virus infection of monkeys. Nef has also been suggested to play a pivotal role in the depletion of T cells by promoting apoptosis in bystander cells. In this context, we investigated the ability of extracellular and endogenously expressed HIV-1 Nef to induce apoptosis in primary human brain microvascular endothelial cells (MVECs). Human brain MVECs were exposed to baculovirus-expressed HIV-1 Nef protein, an HIV-1-based vector expressing Nef, spleen necrosis virus (SNV)-Nef virus (i.e., SNV vector expressing HIV-1 Nef as a transgene), and the HIV-1 strain ADA and its Nef deletion mutant, ADADeltaNef. We observed that ADA Nef, the HIV-1 vector expressing Nef, and SNV-Nef were able to induce apoptosis in a dose-dependent manner. The mutant virus with a deletion in Nef was able to induce apoptosis in MVECs to modest levels, but the effects were not as pronounced as with the wild-type HIV-1 strain, ADA, the HIV-1-based vector expressing Nef, or SNV-Nef viruses. We also demonstrated that relatively high concentrations of exogenous HIV-1 Nef protein were able to induce apoptosis in MVECs. Gene microarray analyses showed increases in the expression of several specific proapoptotic genes. Western blot analyses revealed that the various caspases involved with Nef-induced apoptosis are processed into cleavage products, which occur only during programmed cell death. The results of this study demonstrate that Nef likely contributes to the neuroinvasion and neuropathogenesis of HIV-1, through its effects on select cellular processes, including various apoptotic cascades.