Synergistic lipid-lowering effects of Zingiber mioga and Hippophae rhamnoides extracts.

The effects of a mixture of Hippophae rhamnoides (HR) and Zingiber mioga (ZM) extract (ZH) on intracellular lipid accumulation were investigated in vitro and the anti-obesity effects of ZH evaluated in mice with high-fat diet-induced obesity. The results revealed that ZH inhibited lipid accumulation in 3T3-L1 adipocytes and Huh-7 cells by suppressing adipogenic and lipogenic gene and protein expression. To evaluate the anti-obesity effects of ZH, mice fed a high-fat diet were orally administered low and high doses of ZH (low, ZM 400 mg/kg + HR 100 mg/kg; high, ZM 800 mg/kg + HR 200 mg/kg) for 9 weeks. ZH significantly reduced body weight gain and adipose tissue accumulation with no reduction in food intake when compared to control treatment. Furthermore, ZH reduced hepatic triglyceride and total cholesterol levels, as well as adipose cell size, in the liver and epididymal fat pads, respectively, through inhibition of adipogenesis and lipogenesis-related gene expression. These results suggested that ZH inhibits lipid accumulation, thereby indicating its potential for use as a new therapeutic strategy for obesity.

Autophagy Functions to Prevent Methylglyoxal-Induced Apoptosis in HK-2 Cells.

Methylglyoxal (MGO), a reactive carbonyl species, causes cellular damage and is closely related to kidney disease, particularly diabetic nephropathy. Although MGO has been reported to induce autophagy and apoptosis, the relationships between the two pathways are unclear. Here, we evaluated whether autophagy may be the underlying mechanism inhibiting MGO-induced apoptosis. MGO treatment induced concentration- and time-dependent apoptosis in HK-2 cells. Moreover, MGO upregulated the autophagy markers p62 and LC3-II. Apoptosis caused by MGO was increased in ATG5-knockdown cells compared to that in wild-type cells. In contrast, autophagy activation by 5-aminoimidazole-4-carboxamide ribonucleotide resulted in reduced apoptosis, suggesting that autophagy played a role in protecting against MGO-induced cell death. To examine the mechanisms through which autophagy occurred following MGO stimulation, we investigated changes in AKT/mammalian target of rapamycin (mTOR) signaling. Autophagy induction by MGO treatment was not related to AKT/mTOR signaling; however, it did involve autophagy-related gene expression promoted by AMP-activated protein kinase-mediated transcription factors, such as forkhead box 1. Overall, our findings indicate that MGO-induced cellular damage can be mitigated by autophagy, suggesting that autophagy may be a potential therapeutic target for diseases such as diabetic nephropathy.

Antiobesity effects of the combination of Patrinia scabiosaefolia root and Hippophae rhamnoides leaf extracts.

Patrinia scabiosaefolia (PS) and Hippophae rhamnoides (HR) are traditionally used functional foods. Extracts from the root of PS are known for their anti-inflammatory effects, whereas those from the leaf of HR are effective at both preventing and treating obesity. This study investigated whether the extract combination of PS and HR (PHE) affected weight loss in obese mice. In vitro experiments demonstrated that PHE showed a synergistic effect on inhibiting adipocyte differentiation as compared with treatment with the single extracts. Additionally, PHE suppressed adipogenic-related genes in a concentration-dependent manner. In vivo PHE supplementation suppressed body weight gain, inhibited hepatic lipid accumulation, decreased adipose size, serum triglycerides, and improved insulin resistance in obese mice. These results suggest that a treatment strategy using a combination of plant-derived extracts might be effective at ameliorating obesity. PRACTICAL APPLICATIONS: Currently, common methods for reducing obesity are diet and exercise. These can stimulate oxidative phosphorylation and metabolic activation so have significantly effects. However, these are largely due to individual compliance; there is no significant effect of reducing the worldwide obesity rate. Recently, herbal extracts has been reported as alternative medicine about inflammatory and obesity because diet with the herbal extracts can improve obesity with minimal side effects. Of particular, a mixture of herbal products was investigated for the treatment of obesity. Our reports demonstrated the synergistic effects of natural products and emphasizes the need for studies investigating other combinations of herbal extracts in the treatment of obesity. The results of our studies highlight the synergistic effects of combination phytochemical extracts and their role in ameliorating obesity.

The unc-51 like autophagy activating kinase 1-autophagy related 13 complex has distinct functions in tunicamycin-treated cells.

Endoplasmic reticulum (ER) stress and autophagy are regulated by shared signaling pathways, and their dysfunction is directly related to pathological conditions. This study investigated the function of the unc-51 like autophagy activating kinase 1 (ULK1)-autophagy related 13 (ATG13) complex in ER stress conditions through a knockout (KO) approach. Unlike other autophagy genes, KO of ULK1 or ATG13 attenuated ER stress and promoted mammalian target of rapamycin complex 1 (mTORC1) activation. Compared with wild type (WT) cells, ULK1 and ATG13 KO cells displayed increased viability, while beclin 1, ATG14, and ULK1/2 KO cells did not. Tunicamycin treatment upregulated the expression of ER stress markers (DNA damage inducible transcript 3, heat shock protein family A (Hsp70) member 5, and phosphorylated eukaryotic translation initiation factor 2 alpha kinase 3, eukaryotic translation initiation factor 2 subunit alpha, and endoplasmic reticulum to nucleus signaling 1); however, these were decreased in ULK1 and ATG13 KO cells. Insulin treatment upregulates the phosphorylation of ribosomal protein S6 kinase B1 (RPS6KB1) and AKT serine/threonine kinase 1 (AKT1), which was suppressed by tunicamycin. Notably, ATG13 and ULK1 deficiency ameliorated tunicamycin-induced insulin resistance, with enhanced RPS6KB1 and AKT1 phosphorylation in KO cells compared to WT cells. Although ULK1 and ATG13 are necessary for autophagy induction after tunicamycin-induced ER stress, autophagy does not seem to directly affect tunicamycin-induced cell death, ER stress, or insulin resistance. Our results indicate that loss of the ULK1-ATG13 complex attenuates ER stress and cell death and increases mTORC1 signaling.

Considering the effect of groundwater on bioretention using the Storm Water Management Model.

The Storm Water Management Model (SWMM), with its recently released low impact development (LID) module, is among several models used for the performance evaluation of LID facilities in reducing runoff and pollutants. Modeling is often difficult because of the variety of factors affecting the LID system. Among these factors, the effect of groundwater can be important in the LID modeling results due to the possibility of its interaction with LID. In this study, the performance of the SWMM-LID controls in predicting runoff from bioretention cells was evaluated for a site under groundwater influence. In addition, for considering the groundwater effect in the model, this study explores the utility of the SWMM groundwater model in predicting runoff under groundwater influence. Runoff from the considered watershed draining into the bioretention cells was well-simulated with very favorable performance statistic values (r2 = 0.96, NSE = 0.94, % difference = 2.76). However, comparison of simulated with observed runoff from bioretention cells produced weaker statistical values (r2 = 0.69, NSE = 0.65, % difference = 18.22), which is thought to be due to the presence of events affected by groundwater interference. Removal of these events and recalibration were able to improve the overall results, suggesting that the influence of groundwater should be taken into account for better LID modeling of the study site. In order to consider the groundwater influence, the SWMM groundwater model was used in tandem with LID controls to provide an additional influent source to bioretention cells. This resulted in a good fit for two events which were thought to be impacted by groundwater (events in which outflow exceeded inflow) and overall better performance (r2 = 0.95, NSE = 0.95, % difference = 3.49) compared to the results obtained by using only LID controls. In conclusion, the SWMM groundwater model can help deal with groundwater-impacted events. However, for better representation of the phenomenon, the LID module itself needs to be improved to account for direct interaction with groundwater.

Lactobacillus plantarum-derived Extracellular Vesicles Protect Atopic Dermatitis Induced by Staphylococcus aureus-derived Extracellular Vesicles.

PURPOSE: The microbial environment is an important factor that contributes to the pathogenesis of atopic dermatitis (AD). Recently, it was revealed that not only bacteria itself but also extracellular vesicles (EVs) secreted from bacteria affect the allergic inflammation process. However, almost all research carried out so far was related to local microorganisms, not the systemic microbial distribution. We aimed to compare the bacterial EV composition between AD patients and healthy subjects and to experimentally find out the beneficial effect of some bacterial EV composition. METHODS: Twenty-seven AD patients and 6 healthy control subjects were enrolled. After urine and serum were obtained, EVs were prepared from samples. Metagenomic analysis of 16s ribosomal DNA extracted from the EVs was performed, and bacteria showing the greatest difference between controls and patients were identified. In vitro and in vivo therapeutic effects of significant bacterial EV were evaluated with keratinocytes and with Staphylococcus aureus-induced mouse AD models, respectively. RESULTS: The proportions of Lactococcus, Leuconostoc and Lactobacillus EVs were significantly higher and those of Alicyclobacillus and Propionibacterium were lower in the control group than in the AD patient group. Therefore, lactic acid bacteria were considered to be important ones that contribute to the difference between the patient and control groups. In vitro, interleukin (IL)-6 from keratinocytes and macrophages decreased and cell viability was restored with Lactobacillus plantarum-derived EV treatment prior to S. aureus EV treatment. In S. aureus-induced mouse AD models, L. plantarum-derived EV administration reduced epidermal thickening and the IL-4 level. CONCLUSIONS: We suggested the protective role of lactic acid bacteria in AD based on metagenomic analysis. Experimental findings further suggest that L. plantarum-derived EV could help prevent skin inflammation.

A Metagenomic Analysis Provides a Culture-Independent Pathogen Detection for Atopic Dermatitis.

PURPOSE: Atopic dermatitis (AD) is an inflammatory skin disease, significantly affecting the quality of life. Using AD as a model system, we tested a successive identification of AD-associated microbes, followed by a culture-independent serum detection of the identified microbe. METHODS: A total of 43 genomic DNA preparations from washing fluid of the cubital fossa of 6 healthy controls, skin lesions of 27 AD patients, 10 of which later received treatment (post-treatment), were subjected to high-throughput pyrosequencing on a Roche 454 GS-FLX platform. RESULTS: Microbial diversity was decreased in AD, and was restored following treatment. AD was characterized by the domination of Staphylococcus, Pseudomonas, and Streptococcus, whereas Alcaligenaceae (f), Sediminibacterium, and Lactococcus were characteristic of healthy skin. An enzyme-linked immunosorbent assay (ELISA) showed that serum could be used as a source for the detection of Staphylococcus aureus extracellular vesicles (EVs). S. aureus EV-specific immunoglobulin G (IgG) and immunoglobulin E (IgE) were quantified in the serum. CONCLUSIONS: A metagenomic analysis together with a serum detection of pathogen-specific EVs provides a model for successive identification and diagnosis of pathogens of AD.

Overexpression of MicA induces production of OmpC-enriched outer membrane vesicles that protect against Salmonella challenge.

Outer membrane vesicles (OMVs) derived from bacteria are promising candidates for subunit vaccines. Stresses that modulate the composition of outer membrane proteins (OMPs) are important for OMV synthesis. Small RNAs (sRNAs) expressed in response to stress regulate OMPs, although the mechanism underlying sRNA-mediated OMV biogenesis and its utility for developing vaccine platforms remains to be elucidated. Here, we characterized the role of a sRNA, MicA, which regulates OmpA, a major OMP involved in both production of OMVs and reactive immunity against Salmonella challenge. A Salmonella strain overexpressing MicA generated more OMVs than a control strain. In addition, OmpC was the major component of MicA-derived OMV proteins. MicA-derived OMVs induced Th1- and Th17-type immune responses in vitro and reduced Salmonella-mediated lethality in a mouse model. Thus, OmpA-regulatory sRNA-derived OMVs may facilitate production of Salmonella-protective vaccines.

Helicobacter pylori-derived extracellular vesicles increased in the gastric juices of gastric adenocarcinoma patients and induced inflammation mainly via specific targeting of gastric epithelial cells.

Evidence indicates that Helicobacter pylori is the causative agent of chronic gastritis and perhaps gastric malignancy. Extracellular vesicles (EVs) play an important role in the evolutional process of malignancy due to their genetic material cargo. We aimed to evaluate the clinical significance and biological mechanism of H. pylori EVs on the pathogenesis of gastric malignancy. We performed 16S rDNA-based metagenomic analysis of gastric juices either from endoscopic or surgical patients. From each sample of gastric juices, the bacteria and EVs were isolated. We evaluated the role of H. pylori EVs on the development of gastric inflammation in vitro and in vivo. IVIS spectrum and confocal microscopy were used to examine the distribution of EVs. The metagenomic analyses of the bacteria and EVs showed that Helicobacter and Streptococcus are the two major bacterial genera, and they were significantly increased in abundance in gastric cancer (GC) patients. H. pylori EVs are spherical and contain CagA and VacA. They can induce the production of tumor necrosis factor-α, interleukin (IL)-6 and IL-1ß by macrophages, and IL-8 by gastric epithelial cells. Also, EVs induce the expression of interferon gamma, IL-17 and EV-specific immunoglobulin Gs in vivo in mice. EVs were shown to infiltrate and remain in the mouse stomach for an extended time. H. pylori EVs, which are abundant in the gastric juices of GC patients, can induce inflammation and possibly cancer in the stomach, mainly via the production of inflammatory mediators from gastric epithelial cells after selective uptake by the cells.

Exodisc for Rapid, Size-Selective, and Efficient Isolation and Analysis of Nanoscale Extracellular Vesicles from Biological Samples.

Extracellular vesicles (EVs) are cell-derived, nanoscale vesicles that carry nucleic acids and proteins from their cells of origin and show great potential as biomarkers for many diseases, including cancer. Efficient isolation and detection methods are prerequisites for exploiting their use in clinical settings and understanding their physiological functions. Here, we presented a rapid, label-free, and highly sensitive method for EV isolation and quantification using a lab-on-a-disc integrated with two nanofilters (Exodisc). Starting from raw biological samples, such as cell-culture supernatant (CCS) or cancer-patient urine, fully automated enrichment of EVs in the size range of 20-600 nm was achieved within 30 min using a tabletop-sized centrifugal microfluidic system. Quantitative tests using nanoparticle-tracking analysis confirmed that the Exodisc enabled >95% recovery of EVs from CCS. Additionally, analysis of mRNA retrieved from EVs revealed that the Exodisc provided >100-fold higher concentration of mRNA as compared with the gold-standard ultracentrifugation method. Furthermore, on-disc enzyme-linked immunosorbent assay using urinary EVs isolated from bladder cancer patients showed high levels of CD9 and CD81 expression, suggesting that this method may be potentially useful in clinical settings to test urinary EV-based biomarkers for cancer diagnostics.

House Dust Mite-Derived Chitin Enhances Th2 Cell Response to Inhaled Allergens, Mainly via a TNF-α-Dependent Pathway.

PURPOSE: Chitin is a potent adjuvant in the development of immune response to inhaled allergens in the airways. According to other studies, chitin is known as multi-faced adjuvants which can induce Th2 responses. Recently, we found that TNF-α is a key mediator in the development of Th2 cell response to inhaled allergens. Here, we evaluated the immunologic mechanisms in the development of airway hypersensitivity to inhaled allergens, enhanced by house dust mite (HDM)-derived chitin. METHODS: The role of TNF-α and TLRs was evaluated in an airway hypersensitivity mouse model induced by a sensitization with an allergen (ovalbumin, OVA) and HDM-derived chitin using mice with the null mutation of target genes. RESULTS: The present study showed that airway sensitization with HDM-derived chitin plus OVA enhanced OVA-induced airway inflammation v. OVA alone. This phenotype was associated with the increased expression of Th1, Th2, and Th17 cytokines and also with the enhanced production of OVA-specific IgE, IgG1, and IgG2a. As for T cell responses, OVA-specific Th2 cell response, enhanced by chitin, was abolished by the treatment of chitinase, whereas Th1 and Th17 cell responses enhanced by this treatment. Moreover, the null mutation of the TNF-α gene revealed similar effects as the chitinase treatment. In contrast, all the OVA-specific T cell responses, enhanced by chitin, were blocked by the absence of TLR2, but not of TLR1, TLR4, or TLR6. CONCLUSIONS: In conclusion, these data suggest that HDM-derived chitin may enhance airway hypersensitivity to inhaled allergens, via the TLR2-dependent pathway, and that chitin-induced TNF-α can be a key mediator in the development of Th2 cell response to inhaled allergens.

Vaccination with Klebsiella pneumoniae-derived extracellular vesicles protects against bacteria-induced lethality via both humoral and cellular immunity.

The emergence of multidrug-resistant Klebsiella pneumoniae highlights the need to develop preventive measures to ameliorate Klebsiella infections. Bacteria-derived extracellular vesicles (EVs) are spherical nanometer-sized proteolipids enriched with outer membrane proteins. Gram-negative bacteria-derived EVs have gained interest for use as nonliving complex vaccines. In the present study, we evaluated whether K. pneumoniae-derived EVs confer protection against bacteria-induced lethality. K. pneumoniae-derived EVs isolated from in vitro bacterial culture supernatants induced innate immunity, including the upregulation of co-stimulatory molecule expression and proinflammatory mediator production. EV vaccination via the intraperitoneal route elicited EV-reactive antibodies and interferon-gamma-producing T-cell responses. Three vaccinations with the EVs prevented bacteria-induced lethality. As verified by sera and splenocytes adoptive transfer, the protective effect of EV vaccination was dependent on both humoral and cellular immunity. Taken together, these findings suggest that K. pneumoniae-derived EVs are a novel vaccine candidate against K. pneumoniae infections.

Acetyl salicylic acid inhibits Th17 airway inflammation via blockade of IL-6 and IL-17 positive feedback.

T-helper (Th)17 cell responses are important for the development of neutrophilic inflammatory disease. Recently, we found that acetyl salicylic acid (ASA) inhibited Th17 airway inflammation in an asthma mouse model induced by sensitization with lipopolysaccharide (LPS)-containing allergens. To investigate the mechanism(s) of the inhibitory effect of ASA on the development of Th17 airway inflammation, a neutrophilic asthma mouse model was generated by intranasal sensitization with LPS plus ovalbumin (OVA) and then challenged with OVA alone. Immunologic parameters and airway inflammation were evaluated 6 and 48 h after the last OVA challenge. ASA inhibited the production of interleukin (IL)-17 from lung T cells as well as in vitro Th17 polarization induced by IL-6. Additionally, ASA, but not salicylic acid, suppressed Th17 airway inflammation, which was associated with decreased expression of acetyl-STAT3 (downstream signaling of IL-6) in the lung. Moreover, the production of IL-6 from inflammatory cells, induced by IL-17, was abolished by treatment with ASA, whereas that induced by LPS was not. Altogether, ASA, likely via its acetyl moiety, inhibits Th17 airway inflammation by blockade of IL-6 and IL-17 positive feedback.

Estimation of the relative severity of floods in small ungauged catchments for preliminary observations on flash flood preparedness: a case study in Korea.

An increase in the occurrence of sudden local flooding of great volume and short duration has caused significant danger and loss of life and property in Korea as well as many other parts of the World. Since such floods usually accompanied by rapid runoff and debris flow rise quite quickly with little or no advance warning to prevent flood damage, this study presents a new flash flood indexing methodology to promptly provide preliminary observations regarding emergency preparedness and response to flash flood disasters in small ungauged catchments. Flood runoff hydrographs are generated from a rainfall-runoff model for the annual maximum rainfall series of long-term observed data in the two selected small ungauged catchments. The relative flood severity factors quantifying characteristics of flood runoff hydrographs are standardized by the highest recorded maximum value, and then averaged to obtain the flash flood index only for flash flood events in each study catchment. It is expected that the regression equations between the proposed flash flood index and rainfall characteristics can provide the basis database of the preliminary information for forecasting the local flood severity in order to facilitate flash flood preparedness in small ungauged catchments.

Use of sensor imagery data for surface boundary conditions in regional climate modeling.

Mesoscale climate and hydrology modeling studies have increased in sophistication and are being run at increasingly higher resolutions. Data resolution sufficiently finer than that of the computational model is required not only to support sophisticated linkages and process interactions at small scales but to assess their cumulative impact at larger scales. The global distributions at fine spatial and temporal scales can be described by means of various sensor imagery data collected through remote sensing techniques, sensor image and photo programs, scanning and digitizing skills for existing maps, etc. The availability of global sensor imagery maps facilitates assimilation in land surface models to account for terrestrial dynamics. This study focuses on the use of global imagery data for development and construction of surface boundary conditions (SBCs) specifically designed for mesoscale regional climate model (RCM) applications. The several SBCs are currently presented in a RCM domain for the continent of Asia at 30-km spacing by using sensor imagery data. Geographic Information System (GIS) software application tools are mainly used to convert data information from various raw data onto RCM-specific grids. The raw data sources and processing procedures are elaborated in detail, by which the SBCs can be readily constructed for any specific RCM domain anywhere in the world.

Assessment of vulnerability to extreme flash floods in design storms.

There has been an increase in the occurrence of sudden local flooding of great volume and short duration caused by heavy or excessive rainfall intensity over a small area, which presents the greatest potential danger threat to the natural environment, human life, public health and property, etc. Such flash floods have rapid runoff and debris flow that rises quickly with little or no advance warning to prevent flood damage. This study develops a flash flood index through the average of the same scale relative severity factors quantifying characteristics of hydrographs generated from a rainfall-runoff model for the long-term observed rainfall data in a small ungauged study basin, and presents regression equations between rainfall characteristics and the flash flood index. The aim of this study is to develop flash flood index-duration-frequency relation curves by combining the rainfall intensity-duration-frequency relation and the flash flood index from probability rainfall data in order to evaluate vulnerability to extreme flash floods in design storms. This study is an initial effort to quantify the flash flood severity of design storms for both existing and planned flood control facilities to cope with residual flood risks due to extreme flash floods that have ocurred frequently in recent years.

Effects of cytokines on VEGF expression and secretion by human first trimester trophoblast cell line.

PROBLEM: The mechanism through which vascular endothelial growth factor (VEGF) regulation occurs at the feto-maternal interface is poorly understood. The aim of this study was to investigate the effects of various cytokines on VEGF expression and secretion by trophoblast cells. METHOD OF STUDY: We investigated the effects of cytokines on VEGF expression in human first trimester trophoblast cell line by analyzing VEGF messenger RNA (mRNA) by reverse transcription-polymerase chain reaction and VEGF protein secretion by enzyme linked immunosorbent assay. RESULTS: The trophoblast cells expressed VEGF mRNA constitutively and the main subtypes were identified as VEGF121 and VEGF165. When cultured in the presence of interferon (IFN)-gamma, interleukin (IL)- 1beta, tumor necrosis factor (TNF)-alpha, IL-2, or IL-10, VEGF mRNA expression was found to be significantly increased by IL-1beta, IFN-gamma and TNF-alpha but to be unaffected by IL-2 and IL-10. Moreover, VEGF secretion was most significantly increased by IFN-gamma treatment. CONCLUSION: These results suggest that IL-1beta, IFN-gamma, and TNF-alpha may regulate the production of VEGF in early gestational trophoblasts.

Prognostic value of vascular endothelial growth factor in Stage IB carcinoma of the uterine cervix.

PURPOSE: To clarify the role of vascular endothelial growth factor (VEGF) expression as an independent prognostic factor in Stage IB cervical cancer. METHODS AND MATERIALS: A total of 117 patients with Stage IB cervical cancer who had undergone radical hysterectomy and pelvic lymph node dissection with complete histopathologic examination were included. Eighty-eight (75.2%) patients received postoperative radiotherapy and/or chemotherapy. VEGF expression was examined using immunohistochemistry. RESULTS: Of 117 patients, 35 (29.9%) showed high-intensity VEGF expression and 69 (59%) had a high score for area of VEGF expression. Strong correlations were found between high VEGF intensity and both deep stromal invasion (p = 0.01) and positive pelvic lymph nodes (p = 0.03). The area of VEGF expression was significantly associated with tumor size (p = 0.02). In a multivariate analysis, high VEGF intensity (p = 0.009) and tumor size (p = 0.01) were significant prognostic factors for overall survival and disease-free survival (p = 0.001 and p = 0.003, respectively). However, the area of VEGF expression was not a prognostic factor for overall survival or disease-free survival. CONCLUSION: Our findings on the correlation between VEGF expression and prognosis were conflicting. Functional and quantitative tools to assess tumor angiogenesis in addition to the expression of VEGF need to be developed and would be helpful to support the finding that tumor angiogenesis correlates significantly with prognosis in early-stage cervical cancer.

Arsenic trioxide induces apoptosis in chronic myelogenous leukemia K562 cells: possible involvement of p38 MAP kinase.

Arsenic trioxide (As(2)O(3)) was recently demonstrated to be an effective inducer of apoptosis in patients with relapsed acute promyelocytic leukemia (APL) as well as in patients with APL in whom all-trans-retinoic acid and conventional chemotherapy failed. Chronic myelogenous leukemia cells are highly resistant to chemotherapeutic drugs. To determine if As(2)O(3) might be useful for the treatment of chronic myelogenous leukemia, we examined the ability of As(2)O(3) to induce apoptosis in K562 cells. In vitro cytotoxicity of As(2)O(3) was evaluated in K562 cells by a MTT assay; the IC(50) value for As(2)O(3) was determined to be 10 microM. When analyzed by agarose gel electrophoresis, the DNA fragments became evident after incubation of the cells with 20 microM As(2)O(3) for 24 h. We also found morphological changes and chromatin condensation of the cells undergoing apoptosis. Activation of caspase-3 was observed 6 h after treatment with 20 microM As(2)O(3) by a Western blot analysis. Next, we examined the MAP kinase-signaling pathway of As(2)O(3)-induced apoptosis in K562 cells. As(2)O(3) at 10 microM strongly induced the activation of p38 and JNK 1/2, while ERK 1/2 was inhibited. In addition, pretreatment of SB203580, a specific inhibitor of p38, inhibited As(2)O(3) induced apoptotic cell death. These results suggest that As(2)O(3) is able to induce the apoptotic activity in K562 cells, and its apoptotic mechanism may be associated with the activation of p38.