Antioxidative effects of ethyl 2-(3-(benzo[d]thiazol-2-yl)ureido)acetate against amyloid β-induced oxidative cell death via NF-κB, GSK-3β and β-catenin signaling pathways in cultured cortical neurons

We have previously shown that 2-(3-(benzo[d]thiazol-2-yl)ureido)acetate (KHG21834) attenuates amyloid beta(Aβ)25-35-induced apoptotic death and shows anti-inflammatory activity against Aβ25-35-induced microglial activation. However, antioxidative effects of KHG21834 against Aβ-induced oxidative stress have not yet been reported. In the present study, we investigated the antioxidative function of KHG21834 in primary cultured cortical neurons, to expand the potential therapeutic efficacy of KHG21834. Pretreatment with KHG21834 protected against Aβ-induced neuronal cell death and mitochondrial damage, and significantly restored GSH levels and the activities of catalase, superoxide dismutase, and glutathione peroxidase, and also suppressed the production of reactive oxygen species and protein oxidation. These results imply that KHG21834 may play a role in cellular defense mechanisms against Aβ-induced oxidative stress in cultured cortical neurons. Furthermore, KHG21834 significantly attenuated the effects of Aβ treatment on levels of NF-κB, β-catenin, and GSK-3β proteins in cortical neurons. Taken together, our results suggest that the antioxidant effects of KHG21834 may result at least in part from its ability to regulate the NF-κB, β-catenin, and GSK-3β signaling pathways. To our knowledge, this is the first report showing that KHG21834 significantly attenuates Aβ25-35-induced oxidative stress in primary cortical neurons, and provides novel insights into KHG21834 as a possible therapeutic agent for the treatment of Aβ-mediated neurotoxicity involving oxidative stress.

The Janus face of cathelicidin in tumorigenesis

Cathelicidin is a host defense peptide with multiple innate immunity-related functions. Recent findings indicate that cathelicidin is frequently dysregulated in human cancers where it plays a paradoxical yet dominant role in the regulation of tumor malignancy. In this review, the regulation of malignant phenotypes by cathelicidin in relation to the activation of its receptors and intracellular signaling is discussed.

Rapid genotyping of Plasmodium vivax Pvs25 and Pv38 genes by using mismatch specific endonuclease

Mismatch specific endonuclease (MSE) method was used to detect natural polymorphisms in Pvs25 and Pv38 genes of Plasmodium vivax. Eighty seven patients with P. vivax were recruited in the Republic of Korea (ROK). Pvs25 and Pv38 genes were amplified by polymerase chain reaction (PCR), and the PCR amplicons were mixed with reference DNA sequences. Following the denaturation and gradual annealing, the product mixtures were cleaved by the MSE. Heteroduplex types were readily detected by gel electrophoresis, where extra bands with shorter sizes would appear from the cleavage. After MSE cleavage of 657- bp product from Pvs25 mixtures, three genotypes were detected, while Pv38 mixtures with 1220-bp products presented two genotypes in ROK isolates. After the MSE cleavage, the mismatched samples of Pvs25 and Pv38 were completely sequenced, and the results were in complete agreement with the MSE analyses. In conclusion, genotyping of Pvs25 and Pv38 with MSE cleavage could be a potential method for the high-throughput screening of the large field samples.

Cigarette smoking and gastrointestinal diseases: the causal relationship and underlying molecular mechanisms (review)

Cigarette smoking is an important risk factor for gastrointestinal (GI) disorders, including peptic ulcers, inflammatory bowel diseases, such as Crohn's disease and cancer. In this review, the relationship between smoking and GI disorders and the underlying mechanisms are discussed. It has been demonstrated that cigarette smoking is positively associated with the pathogenesis of peptic ulcers and the delay of ulcer healing. Mechanistic studies have shown that cigarette smoke and its active ingredients can cause mucosal cell death, inhibit cell renewal, decrease blood flow in the GI mucosa and interfere with the mucosal immune system. Cigarette smoking is also an independent risk factor for various types of cancer of the GI tract. In this review, we also summarize the mechanisms through which cigarette smoking induces tumorigenesis and promotes the development of cancer in various sections of the GI tract. These mechanisms include the activation of nicotinic acetylcholine receptors, the formation of DNA adducts, the stimulation of tumor angiogenesis and the modulation of immune responses in the GI mucosa. A full understanding of these pathogenic mechanisms may help us to develop more effective therapies for GI disorders in the future.

Animal models of gastrointestinal inflammation and cancer

Inflammation and cancer are the two major disorders in the gastrointestinal tract. They are causally related in their pathogenesis. It is important to study animal models' causal relationship and, in particular, to discover new therapeutic agents for such diseases. There are several criteria for these models in order to make them useful in better understanding the etiology and treatment of the said diseases in humans. In this regard, animal models should be similar as possible to human diseases and also be easy to produce and reproducible and also economic to allow a continuous replication in different laboratories. In this review, we summarize the various animal models for inflammatory and cancerous disorders in the upper and lower gastrointestinal tract. Experimental approaches are as simple as by giving a single oral dose of alcohol or other noxious agents or by injections of multiple dosages of ulcer inducing agents or by parenteral administration or in drinking water of carcinogens or by modifying the genetic makeups of animals to produce relatively long-term pathological changes in particular organs. With these methods they could induce consistent inflammatory responses or tumorigenesis in the gastrointestinal mucosa. These animal models are widely used in laboratories in understanding the pathogenesis as well as the mechanisms of action for therapeutic agents in the treatment of gastrointestinal inflammation and cancer.

Dihydrotanshinone induces p53-independent but ROS-dependent apoptosis in colon cancer cells

AIMS

The therapeutic potential of various tanshinones was examined and compared for their anti-cancer activities on colon cancer cells. The role of ROS generation in the pro-apoptotic activity of dihydrotanshinone (DHTS) was further studied.

MAIN METHODS

Cell viability was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis and poly-ADP-ribose-polymerase (PARP) cleavage were respectively measured by flow cytometer and Western blot. Changes of mitochondrial membrane potential (MMP), mitochondrial ROS (mitoROS) and total ROS were determined by confocal system under an inverted microscope.

KEY FINDINGS

Among the different tanshinones examined, DHTS produced the most potent anti-cancer effect. DHTS induced a selective cytotoxicity and apoptosis in both HCT116 p53(-/-) and HCT116 p53(+/+) colon cancer cells. A time- and concentration-dependent PARP cleavage further confirmed the apoptotic activity. In this regard, it was found DHTS provoked mitochondrial dysfunction in the early stage by decreasing MMP and mitoROS levels. This was followed by a time-dependent increase in intracellular ROS generation. Pretreatment with N-acetyl-l-cysteine (NAC) or catalase-PEG, the free radical scavengers, reduced apoptotic cell death. From these findings, it seems that leakage of ROS from mitochondria into cytosol by DHTS represents the major contributory factor leading to cell death in colon cancer cells.

SIGNIFICANCE

We report for the first time that DHTS induces apoptosis in colon cancer cells through a p53-independent pathway. Disturbance of ROS generation at the oxidative phosphorylation (OXPHOS) complex in mitochondria followed by the decrease of MMP and increase of intracellular ROS accumulation are suggested to be involved in the pro-apoptotic activity of DHTS.

A comparison of outcomes between concurrent chemoradiotherapy and radiotherapy alone in cancer of the uterine cervix: a single institutional experience

PURPOSE

To compare failure patterns and evaluate prognostic factors related to survival rates after concurrent chemoradiotherapy (CCRT) or radiotherapy (RT) alone in cervical cancer.

MATERIALS AND METHODS

From January 1996 to December 2006, 218 patients with cervical cancer (FIGO Stage IB2 - III) treated with CCRT or RT alone as primary treatments were included, retrospectively. One-hundred eight patients were treated with CCRT and 110 with RT alone.

RESULTS

There was no significant difference in failure patterns between the treatment groups, but distant metastasis was the predominant pattern in both groups. The frequent metastatic sites were supraclavicular lymph node, lung, and brain. Treatment group, diabetes, and FIGO Stage were found to be significant for overall survival (OS) and disease-free survival (DFS), and initial hemoglobin level for DFS.

CONCLUSION

Distant metastasis is the predominant failure pattern and diabetes is one of the independent prognostic factors to survival rates in this study.

Cathelicidin protects against Helicobacter pylori colonization and the associated gastritis in mice

Cathelicidin, an antimicrobial peptide of the innate immune system, has been shown to modulate microbial growth, wound healing and inflammation. However, whether cathelicidin controls Helicobacter pylori infection in vivo remains unexplored. This study sought to elucidate the role of endogenous and exogenous mouse cathelicidin (CRAMP) in the protection against H. pylori infection and the associated gastritis in mice. Results showed that genetic ablation of CRAMP in mice significantly increased the susceptibility of H. pylori colonization and the associated gastritis as compared with the wild-type control. Furthermore, replenishment with exogenous CRAMP, delivered via a bioengineered CRAMP-secreting strain of Lactococcus lactis, reduced H. pylori density in the stomach as well as the associated inflammatory cell infiltration and cytokine production. Collectively, these findings indicate that cathelicidin protects against H. pylori infection and its associated gastritis in vivo. Our study also demonstrates the feasibility of using the transformed food-grade bacteria to deliver cathelicidin, which may have potential clinical applications in the treatment of H. pylori infection in humans.

Effects of Radix Astragali and Radix Rehmanniae, the components of an anti-diabetic foot ulcer herbal formula, on metabolism of model CYP1A2, CYP2C9, CYP2D6, CYP2E1 and CYP3A4 probe substrates in pooled human liver microsomes and specific CYP isoforms

The present study investigated the effects of Radix Astragali (RA) and Radix Rehmanniae (RR), the major components of an anti-diabetic foot ulcer herbal formula (NF3), on the metabolism of model probe substrates of human CYP isoforms, CYP1A2, CYP2C9, CYP2D6, CYP2E1 and CYP3A4, which are important in the metabolism of a variety of xenobiotics. The effects of RA or RR on human CYP1A2 (phenacetin O-deethylase), CYP2C9 (tolbutamide 4-hydroxylase), CYP2D6 (dextromethorphan O-demethylase), CYP2E1 (chlorzoxazone 6-hydroxylase) and CYP3A4 (testosterone 6β-hydroxylase) activities were investigated using pooled human liver microsomes. NF3 competitively inhibited activities of CYP2C9 (IC(50)=0.98mg/ml) and CYP3A4 (IC(50)=0.76mg/ml), with K(i) of 0.67 and 1.0mg/ml, respectively. With specific human CYP2C9 and CYP3A4 isoforms, NF3 competitively inhibited activities of CYP2C9 (IC(50)=0.86mg/ml) and CYP3A4 (IC(50)=0.88mg/ml), with K(i) of 0.57 and 1.6mg/ml, respectively. Studies on RA or RR individually showed that RR was more important in the metabolic interaction with the model CYP probe substrates. RR dose-dependently inhibited the testosterone 6β-hydroxylation (K(i)=0.33mg/ml) while RA showed only minimal metabolic interaction potential with the model CYP probe substrates studied. This study showed that RR and the NF3 formula are metabolized mainly by CYP2C9 and/or CYP3A4, but weakly by CYP1A2, CYP2D6 and CYP2E1. The relatively high K(i) values of NF3 (for CYP2C9 and CYP3A4 metabolism) and RR (for CYP3A4 metabolism) would suggest a low potential for NF3 to cause herb-drug interaction involving these CYP isoforms.

High voltage ultrawide band pulse generator using Blumlein pulse forming line

A high voltage ultrawide band pulse generation system has been developed to radiate intense and ultrawide band electric fields for the examination of effects of the electric fields on the operation of electronic devices. As major components of the system, a helical strip∕wire type of air-cored pulse transformer and a triaxial type of Blumlein pulse forming line have been designed and fabricated to amplify and shape the output pulse, respectively. For the construction of a compact system, the pulse transformer and the Blumlein line are installed in a single cylindrical container. An ultrawide band TEM horn antenna has been fabricated to radiate the Blumlein output pulses to electronic devices. A number of experimental results demonstrate that the system is capable of providing an output pulse whose voltage is greater than 300 kV, pulse duration is ~5 ns, and rise time is ~500 ps with repetition rate of 10 Hz. The peak-to-peak value of electric field intensity of a radiated pulse is also measured to be approximately 42 kV/m at a distance of 10 m away from the antenna.

Intrarectal administration of mCRAMP-encoding plasmid reverses exacerbated colitis in Cnlp(-/-) mice

Cathelicidin is a pleiotropic host defense peptide secreted by epithelial and immune cells. Whether endogenous cathelicidin is protective against ulcerative colitis, however, is unclear. Here we sought to delineate the role of endogenous murine cathelicidin (mCRAMP) and the therapeutic efficacy of intrarectal administration of mCRAMP-encoding plasmid in ulcerative colitis using dextran sulfate sodium (DSS)-challenged cathelicidin-knockout (Cnlp(-/-)) mice as a model. Cnlp(-/-) mice had more severe symptoms and mucosal disruption than the wild-type mice in response to DSS challenge. The tissue levels of interleukin-1β and tumor necrosis factor-α, myeloperoxidase activity and the number of apoptotic cells were increased in the colon of DSS-challenged Cnlp(-/-) mice. Moreover, mucus secretion and mucin gene expression were impaired in Cnlp(-/-) mice. All these abnormalities were reversed by the intrarectal administration of mCRAMP or mCRAMP-encoding plasmid. Taken together, endogenous cathelicidin may protect against ulcerative colitis through modulation of inflammation and mucus secretion.

Extracts from Radix Astragali and Radix Rehmanniae promote keratinocyte proliferation by regulating expression of growth factor receptors

Chinese herbal medicine has long been used as a treatment for wounds. However, the underlying cellular and molecular mechanisms remain largely unknown. In this study it was shown that the proliferation of keratinocytes, which is known to play an important role in wound healing as the major cell type in the epidermis, was promoted by three herbal extracts/natural compounds: NF3 (an extract from the mixture of Radix Astragali (RA) and Radix Rehmanniae (RR) in the ratio of 2:1), stachyose (an isolated compound from Radix Rehmanniae) and extract P2-2 (a sub-fraction from the extract of Radix Astragali). The effect of the herbal extracts/natural compounds on the growth of keratinocytes was not influenced by a high glucose level, a condition similar to diabetic patients who usually suffer from diabetic foot ulcers. Real time RT-PCR results showed that the expression of epidermal growth factor (EGF) receptor, but not transforming growth factor-β (TGF-β) receptor, was up-regulated by NF3. Moreover, treatments with the EGF receptor kinase inhibitor AG1478 and the MEK inhibitor U0126 resulted in the diminishment of the effect of the three herbal extracts/natural compounds on keratinocyte proliferation, indicating that EGF receptor might have a significant role in this action. This study has further elucidated the molecular mechanism under which herbal extracts/natural compounds exert their effects on the wound healing process.

The autophagic paradox in cancer therapy

Autophagy, hallmarked by the formation of double-membrane bound organelles known as autophagosomes, is a lysosome-dependent pathway for protein degradation. The role of autophagy in carcinogenesis is context dependent. As a tumor-suppressing mechanism in early-stage carcinogenesis, autophagy inhibits inflammation and promotes genomic stability. Moreover, disruption of autophagy-related genes accelerates tumorigenesis in animals. However, autophagy may also act as a pro-survival mechanism to protect cancer cells from various forms of cellular stress. In cancer therapy, adaptive autophagy in cancer cells sustains tumor growth and survival in face of the toxicity of cancer therapy. To this end, inhibition of autophagy may sensitize cancer cells to chemotherapeutic agents and ionizing radiation. Nevertheless, in certain circumstances, autophagy mediates the therapeutic effects of some anticancer agents. Data from recent studies are beginning to unveil the apparently paradoxical nature of autophagy as a cell-fate decision machinery. Taken together, modulation of autophagy is a novel approach for enhancing the efficacy of existing cancer therapy, but its Janus-faced nature may complicate the clinical development of autophagy modulators as anticancer therapeutics.

Adaptive cytoprotection and the brain-gut axis

Adaptive cytoprotection is a concept to counteract against the gastric mucosal injury caused by stress, strong irritants and drugs such as non-steroidal anti-inflammatory drugs. The process is mediated through diverse mediators and mechanisms. Studies on adaptive cytoprotection began from the discovery of prostaglandin (PG)-dependent and PG-independent pathways, followed by the investigation on the types and concentrations of mild irritants to be used. Upon the confirmation on the importance of the vagus nerve and the vago-vagal pathway in regulating the mucosal protective actions of the mild irritants, individual participating mediators for the neuronal modulatory processes were explored, including peptide neurotransmitters such as calcitonin gene-related peptide and substance P. Further correlation with the sympathetic nervous system, the sensory afferent neurons and the enteric nervous system of the gastric mucosa had been made. A close working relationship between the hypothalamic-pituitary-adrenal axis, the autonomic nervous system and the enteric nervous system was then proposed, with concurrent regulation of PG, nitric oxide and sensory neuropeptides by different mild irritants. Apart from these conventional concepts, there are now contemporary ideas on newer forms of adaptive cytoprotection such as ischemic preconditioning and heat-shock proteins, which will cast new light to novel approaches in facilitating gastric mucosal protection.

Effect of NF-κB signaling on apoptosis in chronic inflammation-associated carcinogenesis

The causal relationship between inflammation and cancer has been documented for sometime, but its molecular nature remains ill defined. Increasing evidence suggested that inflammatory microenvironment in and around tumors is an indispensable participant in the neoplastic process. High level of free radicals produced during inflammation significantly induces DNA damage while evading apoptosis, a hallmark of cancer, reduces the capability of tissues to eliminate damaged cells. Therefore, the mechanism by which inflammation affects the apoptosis pathway is crucial to understand inflammation-associated carcinogenesis. Nuclear factor-κB (NF-κB), a transcriptional factor, plays an important role in the regulation of inflammatory responses. NF-κB signaling, which can be activated by diverse stimuli including proinflammatory cytokines, infectious agents and cellular stresses, has been shown to involve in carcinogenesis and resistance to multiple drug therapy. In this review, we focus on the role of NF-κB signaling on the apoptotic effect in inflammation-associated carcinogenesis. These insights may help us to consider the role of NF-κB in inflammation and cancer and further on as a target of drugs for the prevention and treatment of these diseases.

The cytoprotective effect of zinc l-carnosine on ethanol-induced gastric gland damage in rabbits

The effects of zinc l-carnosine on the damaging actions of ethanol were examined in rabbit isolated gastric glands. Ethanol (8%, v/v) incubation produced a 50% viability of the gland populations and released a significant amount (38%) of the total lactate dehydrogenase (an index of membrane injury) of the glands. Zinc l-carnosine pre-incubation for 15 min markedly prevented these actions of ethanol; however, l-carnosine by itself did not have these effects. These findings indicate that zinc ion but not carnosine in the zinc l-carnosine molecule possesses cytoprotective action against ethanol-induced gastric gland damage in rabbits.

Polyethylene glycol: its adverse gastric effects in rats

The effects of polyethylene glycol (PEG) on gastric function and on lesion formation, evoked by topical applications of absolute ethanol to an ex-vivo stomach chamber preparation have been examined. Parenteral injection (i.p. or s.c.) of PEG with different molecular weights (PEG 300, 400 or 4000), dose-dependently reduced the gastric mucosal blood flow and volume of gastric secretion; these effects were greater in rats given PEG by the i.p. route, which also lowered acid output. Topical application of 1·5 mL absolute ethanol produced severe gastric mucosal injury, which was exacerbated by PEG; this lesion-aggravating effect was higher in the i.p.-injected groups. These findings indicate that when PEG is given by injection, it can adversely affect gastric function and increase the damaging action of alcohol. It is suggested that the use of PEG as a vehicle for injection should be re-assessed.

Nano-electromechanical switch-CMOS hybrid technology and its applications

Si-based CMOS technology is facing a serious challenge in terms of power consumption and variability. The increasing costs associated with physical scaling have motivated a search for alternative approaches. Hybridization of nano-electromechanical (NEM)-switch and Si-based CMOS devices has shown a theoretical feasibility for power management, but a huge technical gap must be bridged before a nanoscale NEM switch can be realized due to insufficient material development and the limited understanding of its reliability characteristics. These authors propose the use of a multilayer graphene as a nanoscale cantilever material for a nanoscale NEM switchwith dimensions comparable to those of the state-of-the-art Si-based CMOS devices. The optimal thickness for the multilayer graphene (about five layers) is suggested based on an analytical model. Multilayer graphene can provide the highest Young's modulus among the known electrode materials and a yielding strength that allows more than 15% bending. Further research on material screening and device integration is needed, however, to realize the promises of the hybridization of NEM-switch and Si-based CMOS devices.

Inhibition of acute experimental colitis by a crude extract and diets containing seeds of Garcinia kola (heckel)

The protective effect of Garcinia kola (GK) crude extract on acetic acid induced colitis in rats was investigated. Colitis, a form of inflammatory bowel disease (IBD) is characterized by inflammation of colon. The pathology in colitis includes disruption of crypt architecture, inflammation of crypts, frank crypt abscesses, and hemorrhage or inflammatory cells in the lamina propria. Since oxidative stress plays an important role in the etiology of Inflammatory Bowel diseases,and Garcinia kola (GK), have been shown to reduce oxidative stress in the rat stomach.The present study was designed to investigate the effects of Garcinia kola on ulcerative colitis (UC) induced by acetic acid. Albino rats were divided into five groups; Group one served as control, group two received Normal saline, group three received 2.5% ethanol while groups four and five were given 20mg/kg and 100mg/kg of crude extract of Garcinia kolarespectively. In another experiment, rats were fed for 2 weeks on normal rat diets but specially composed to contain 12.5%, 25% and 50% by weight of G kola. Colitis was induced by intra-rectal administration of 6% acetic acid. The colonic damage was elucidated by macroscopic damage scores; colon wet weight, stool consistency and colonic edema (thickness of the colon). Intra-luminal administration of 6% acetic acid resulted in observable clinical and macroscopic signs of colitis.Pre-orally administered of crude extract of GK significantly reduced the colonic damage score (p<0.001), colon weight (p<0.001), thickness of the colon (p<0.001) and diarrhea (p<0.001).Histological examinations also indicated a marked reduction in tissue injury and inhibition in neutrophil infiltration in rats pretreated with crude extract of Garcinia kola. Results of this investigation provide experimental evidence of Garcinia kola as an anti-colitis agent.

Anti-inflammatory activities of a kolaviron-inhibition of nitric oxide, prostaglandin E2 and tumor necrosis factor-alpha production in activated macrophage-like cell line

Kolaviron (KV), a biflavonoid fraction from the seeds of Garcinia kola has been shown to posess antiinflammatory properties in animal models of inflammation. In this study, the effect of KV on carrageenan-induced paw edema was investigated in mice. Furthermore, the effects of KV on the production of the pro-inflammatory mediators- nitric oxide (NO) and tumor necrosis factor alpha (TNF-alpha) were examined in an activated macrophage-like cell lines, RAW 264.7 cells. Administration of KV prior to injection of carrageenan significantly reduced the paw inflammation in a dose-dependent manner. KV consistently inhibited in-vitro production of NO and secretion of TNF-alpha in a dose-dependent manner. In addition, KV reduced the production of PGE2 in LPS-stimulated macrophages. Viability of cells at all concentrations studied was unaffected as determined MTT [3-(4,5- dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide] cytotoxicity assay. These results suggest that KV has inhibitory effects on LPS-induced TNF-alpha, NO and PGE2 production.

Catecholamines inhibit gastric epithelial [RGM-1] cell proliferation via β adrenoceptors

Catecholamines have been implicated in the modulation of normal cell growth, exerting inhibitory or excitatory control depending on the cell type. However, there is a dearth of information on the role of adrenergic mediators in gastric cell proliferation. In the present study, the effects of adrenaline (ADR) and noradrenaline (NOR) on mucosal cell growth and the cell cycle were evaluated in vitro using a normal rat gastric mucosal cell line RGM-1. Cell proliferation was assessed using [3H]-thymidine incorporation and cell cycle patterns were determined by DNA labeling with propidium iodide and flow cytometric quantification. The expressions of adrenoceptors in RGM-1 were determined by Western blot. ADR (0.01 - 10µM) and NOR (0.01 - 10µM) inhibited the growth of RGM-1 cells in a concentration-dependent manner. Pre-treatment of cells with ADR and NOR also inhibited the proliferation stimulated by epidermal growth factor (EGF). Neither phentolamine (non-selective α-adrenergic blocker), methoxamine (α1-selective agonist) nor clonidine (α2-selective agonist) significantly affected the inhibition of cell proliferation produced by ADR and NOR. Propranolol (non-selective β-adrenergic blocker) and butoxamine (selective β2-adrenergic blocker) significantly (but not totally) reversed the inhibitory action of ADR on cell proliferation. Furthermore, procaterol (selective beta-2 agonist) but not dobutamine (selective beta-1 agonist) had effects similar to those produced by ADR and NOR. Exposure of RGM-1 cells to both ADR and NOR caused significant inhibition of the G1 - S cycle progression as evidenced by the higher percentage of the G0/G1 phase and a decreased S- phase. This effect was blocked by pre-treatment with propranolol but not phentolamine These results indicate that catecholamines inhibit the proliferation of RGM-1 cells probably partly through beta-2 receptors.

MicroRNA dysregulation in gastric cancer: a new player enters the game

Gastric carcinogenesis is a multistep process involving genetic and epigenetic alteration of protein-coding proto-oncogenes and tumor-suppressor genes. Recent discoveries have shed new light on the involvement of a class of noncoding RNA known as microRNA (miRNA) in gastric cancer. A substantial number of miRNAs show differential expression in gastric cancer tissues. Genes coding for these miRNAs have been characterized as novel proto-oncogenes and tumor-suppressor genes based on findings that these miRNAs control malignant phenotypes of gastric cancer cells. In this connection, miRNA dysregulation promotes cell-cycle progression, confers resistance to apoptosis, and enhances invasiveness and metastasis. Moreover, certain polymorphisms in miRNA genes are associated with increased risks for atrophic gastritis and gastric cancer, whereas circulating levels of miRNAs may serve as biomarkers for early diagnosis. Several miRNAs have also been shown to correlate with gastric cancer progression, and thus may be used as prognostic markers. Elucidating the biological aspects of miRNA dysregulation may help us better understand the pathogenesis of gastric cancer and promote the development of miRNA-directed therapeutics against this deadly disease.

Chinese green tea ameliorates lung injury in cigarette smoke-exposed rats

BACKGROUND

Epigallocatechin-3-gallate (EGCG), which has been shown to have potent antioxidant effect, comprises 80% of catechins in Chinese green tea. This study was to investigate whether cigarette smoke (CS) exposure would induce lung morphological changes and oxidative stress in the CS-exposed rat model, and whether Chinese green tea (Lung Chen tea with EGCG as its main active ingredient) consumption would alter oxidative stress in sera and lung leading to protection of CS-induced lung damage.

METHODS

Sprague-Dawley rats were randomly divided into four groups, i.e. sham air (SA), 4% CS, 2% Lung Chen tea plus SA or 4% CS. Exposure to SA or 4% CS was performed for 1h/day for 56 days in ventilated smoking chambers. Sera and lung tissues were collected 24h after last CS exposure for histology and all biochemical assays.

RESULTS

Airspace enlargement and goblet cell hyperplasia were observed after 56-day CS exposure alone, which were abolished in the presence of green tea consumption. Serum 8-isoprostane level was significantly elevated (p<0.01) as well as lung superoxide dismutase (SOD) and catalase activities in CS-exposed rats compared to SA-exposed rats (p<0.05), which returned to the levels of SA-exposed rats after Chinese green tea consumption.

CONCLUSION

These results indicate that increased levels of systemic oxidative stress after CS exposure play an important role in the induction of lung damage. Chinese green tea may have the ability to suppress CS-induced oxidative stress that leads to protection of lung injury.