Jeong-Sang Lee

Oxidative damages are critical in pathogenesis of reflux esophagitis: implication of antioxidants in its treatment

Abstract Background: The facts that the severity of reflux esophagitis cannot be accurately predicted on the basis of acid exposure and acid suppression treatment is not enough for the complete healing, suggested that other damaging factors might be involved in pathogenesis of reflux esophagitis. Aims: The present study was designed to evaluate the oxidative stress as the major pathogenic factor of reflux esophagitis and the importance of antioxidant in treatment of reflux esophagitis. Materials and Methods: Reflux esophagitis was induced by the insertion of small caliber ring (3 mm in diameter) into the duodenum 1 cm distal to the ligament of Treitz in rats. Results: DA-9601, a novel antioxidant substance, attenuated the gross esophagitis significantly compared to that treated with ranitidine, histamine-2 receptor antagonist (H2-RA), in a dose-dependent manner. Severe, hemorrhagic, and longitudinal ulcerations were developed in H2-RA pretreated group, whereas mildly scattered erosions were observed in antioxidant-pretreated group. Significantly increased amounts of malondialdehyde (MDA), increased NF-κB activation, and the mucosal depletion of reduced glutathione (GSH) were observed in the esophagus of reflux esophagitis. H2-RA treatment didn’t affect the levels of GSH and MDA, whereas DA-9601 attenuated the decrement of the GSH levels and significantly decreased lipid peroxides in the esophagus. Antioxidants treatment showed significant reductions in the activation of NF-κB, inflammation-associated transcription factor, especially p50 component in accordance with significant higher levels of NF-κB repressor, IκBα expression. Conclusion: Oxygen-derived free radicals seem to be one of the important mediators in generation of reflux esophagitis, which suggests that the combination of antioxidant and anti-secretory medications will be ideal and more beneficial in the prevention and treatment of reflux esophagitis than currently prescribed antisecretory treatment alone.

Resveratrol and Piceatannol Inhibit iNOS Expression and NF-κ B Activation in Dextran Sulfate Sodium-Induced Mouse Colitis

Inflammatory tissue injury has been implicated in tumor promotion and progression. 3,5,4′-trihydroxy-trans-stilbene (resveratrol) and 3,4,3′, 5′-tetrahydroxy-trans-stilbene (piceatannol), 2 structurally related plant polyphenols, have been reported to possess antioxidant, anti-inflammatory, and chemopreventive properties. This study was aimed at investigating the possible protective effects of resveratrol and piceatannol against dextran sulfate sodium (DSS)-induced inflammation in mouse colonic mucosa. Administration of DSS (2.5%) in drinking water for 7 days to male ICR mice resulted in colitis and elevated expression of inducible nitric oxide synthase (iNOS) and activation of nuclear factor-kappa B (NF-κB), a major transcription factor known to upregulate proinflammatory gene expression. Phosphorylation of extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription-3 (STAT3) was also enhanced after DSS treatment. Oral administration of resveratrol or piceatannol (10 mg/kg body weight each) for 7 constitutive days attenuated the DSS-induced inflammatory injury, upregulation of iNOS expression, and activation of NF-κB, STAT3, and ERK.

Preclinical and Phase I Clinical Studies with Ckd-602, a Novel Camptothecin Derivative

Preclinical studies of CKD-602 demonstrated broad antitumor activity against various human tumor cell lines, and the results were equal or superior to those of camptothecin (CPT) and topotecan (TPT), a clinically active antitumor drug.2,3 CKD-602 was less active than CPT against L1210 in vitro; the IC50 value was 0.55 μg/ml and 0.2 μg/ml, respectively. However, it showed superior in vivo antitumor activity to CPT against L1210 (ILS% was 168 and 110, respectively), and superior to TPT against L1210 leukemia (ILS% was 168 and 127, respectively), P388 leukemia, Lewis lung carcinoma, and B16 melanoma. CKD-602 treatment resulted in tumor regression, extensive tumor growth delays even in highly resistant CX-1 colon tumor (the IR% of CKD-602 was 88, whereas that of TPT was 70), and a broader therapeutic dosage range than TPT ([R/E]max value was 1.33 and 3.44, respectively). Preliminary studies showed that the intermittent dosing schedule showed superior antitumor activity to a single dose schedule.4 In studies of CKD-602 against a panel of human tumor xenografts comprised of colon and breast carcinoma, greater activity and higher [R/E]max values were obtained than with TPT.

Novel antioxidant ameliorates the fibrosis and inflammation of cerulein-induced chronic pancreatitis in a mouse model.

Background/Aim: Oxygen free radicals (OFRs) mediate an important step in the initiation of experimental acute pancreatitis and several clinical findings suggested the possible contribution of OFRs to the pathogenesis of pancreatic fibrosis. So far, there are no studies which reporting potential role of OFRs in development of chronic pancreatitis with the prevention with antioxidants. This study was aimed to establish the mice model of chronic fibrosing pancreatitis and to prove the involvement of OFRs in chronic pancreatitis with fibrosis. Methods: Repeated intraperitoneal cerulein injection was performed to induce chronic pancreatitis in mice. Histological changes in the pancreas were examined, and markers for oxidative stress were measured in the pancreatic tissue and serum of the mice. DA-9601, a phytochemical possessing anti-inflammatory and antioxidative action, was given together with cerulein to the mice. Results: Repeated intraperitoneal injection of cerulein provoked significant severity of chronic fibrosing pancreatitis after 5 weeks. After treatment of DA-9601, the extents of pancreatic fibrosis were statistically significantly decreased in accordance with lessened pancreatic inflammations. The NF-ĸB binding activities were increased in chronic pancreatitis, which were significantly attenuated after DA-9601 treatment. The levels of myeloperoxidase and iNOS activities were also significantly decreased in DA-9601-treated group compared to the pancreatitis only group. Cytoprotective proteins such as heat shock protein-70 (HSP) and metallothionein were significantly increased in the DA-9601-treated group. DA-9601 decreased the expressions of α-SMA and type I collagen in cultured pancreatic stellate cells. Conclusions: Oxidative stress was principally involved in the pathogenesis of chronic pancreatitis with fibrosis.

Zerumbone Induces Heme Oxygenase-1 Expression in Mouse Skin and Cultured Murine Epidermal Cells through Activation of Nrf2

Zerumbone, a sesquiterpene derived from tropical ginger, contains an electrophilic α,β-unsaturated carbonyl moiety and was found to suppress chemically induced papilloma formation in mouse skin. Here, we report that topical application of zerumbone onto dorsal skin of hairless mice induces activation of NF-E2–related factor 2 (Nrf2) and expression of heme oxygenase-1 (HO-1). We compared the levels of HO-1 protein in the skin of zerumbone-treated Nrf2 wild-type and Nrf2 knockout mice, and nrf2-deficient mice expressed HO-1 protein to a much lesser extent than the wild-type animals following topical application of zerumbone. Treatment of mouse epidermal JB6 cells with zerumbone caused a marked increase of Nrf2 nuclear translocation followed by the promoter activity of HO-1, and also enhanced direct binding of Nrf2 to the antioxidant response element. Moreover, knockdown of Nrf2 in JB6 cells diminished the zerumbone-induced upregulation of HO-1. Notably, α-humulene and 8-hydroxy-α-humulene, the structural analogues of zerumbone that lack the α,β-unsaturated carbonyl group, failed to activate Nrf2 and were unable to increase HO-1 expression. Unlike zerumbone, these nonelectrophilic analogues could not suppress the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced JB6 cell transformation and the intracellular accumulation of reactive oxygen species (ROS). Interestingly, when JB6 cells were treated with carbon monoxide–releasing molecule that mimics the HO-1 activity, the TPA-induced ROS production was markedly reduced. Taken together, these findings suggest that upregulation of HO-1 expression by zerumbone is mediated through activation of Nrf2 signaling, which provides a mechanistic basis for the chemopreventive effects of this sesquiterpene on mouse skin carcinogenesis. Cancer Prev Res; 4(6); 860–70. ©2011 AACR.

Inhibition of Cyclooxygenase-2 Expression and Restoration of Gap Junction Intercellular Communication in H-ras-Transformed Rat Liver Epithelial Cells by Caffeic Acid Phenethyl Ester

Abstract: One of the most frequent defects in human cancers is the uncontrolled activation of the ras signaling pathways. Increased expression of cyclooxygenase‐2 (COX‐2) and inhibition of gap junction intercellular communication (GJIC) have been frequently observed in several forms of human malignancies. The present study investigated the effects of caffeic acid phenethyl ester (CAPE), a chemopreventive phytochemical derived from honey propolis, on COX‐2 expression and GJIC in Harvey‐ras‐transformed WB‐F344 rat liver epithelial cells (H‐ras WB cells). H‐ras induced COX‐2 expression in WB‐F344 rat liver epithelial cells (WB cells). H‐ras WB cells also exhibited complete inhibition of GJIC and predominant unphosphorylation of connexin 43 (Cx43), a major protein modulating GJIC. CAPE significantly inhibited the constitutive expression of COX‐2 and restored the disrupted GJIC through the phosphorylation of Cx43 at a concentration of 12.5 μM in H‐ras WB cells. Although the molecular basis for the cancer chemopreventive activity of CAPE is not completely understood, several studies suggest that CAPE is a potent and specific inhibitor of the transcription factor nuclear factor κB (NF‐κB) activation. We also found that CAPE significantly inhibited H‐ras‐induced NF‐κB DNA‐binding activity without affecting the activation of extracellular signal‐regulated kinase and p38 mitogen‐activated protein kinase, which are major intracellular molecules involved in the Ras signaling pathways. In conclusion, CAPE may exert cancer chemopreventive effects through the inhibition of COX‐2 expression and the restoration of disrupted GJIC induced by H‐ras, possibly by targeting NF‐κB.

IRON ENHANCEMENT OF OXIDATIVE DNA DAMAGE AND NEURONAL CELL DEATH INDUCED BY SALSOLINOL

A group of naturally occurring isoquinoline alkaloids have been detected in certain regions of mammalian brain. One such compound is salsolinol (SAL; 1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline). This endogenous isoquinoline derivative has been considered to be implicated in the pathophysiology of chronic alcoholism and Parkinsonism. The present study deals with the DNA strand scission induced by SAL in the presence of iron. Incubation of φX174 DNA with SAL and ferric ion led to conversion of the supercoiled DNA to open circular and linear forms, which was inhibited by the iron chelator deferoxamine, catalase, and scavengers of reactive oxygen species. SAL in combination with Fe(III) also produced 8-hydroxydeoxyguanosine in calf thymus DNA. Exposure of PC12 cells to SAL produced concentration-dependent reduction in viability, which was exacerbated by iron and ameliorated by deferoxamine.

Chemopreventive Effects of the Standardized Extract (DA-9601) of Artemisia asiatica on Azoxymethane-Initiated and Dextran Sulfate Sodium-Promoted Mouse Colon Carcinogenesis

Dextran sulfate sodium (DSS) administration has been reported to cause inflammation in mouse colonic mucosa, which promotes colon carcinogenesis. When male ICR mice were treated with a single intraperitoneal dose (10 mg/kg body weight) of azoxymethane (AOM) followed by 2.5% DSS in drinking water for 7 consecutive days, all developed tumors at the 16th wk, mostly in the distal colon. Cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) were markedly upregulated in the AOM-initiated and DSS-promoted colon tumors. The DNA binding activity of nuclear factor-kappaB (NF-κ B) was also elevated in the colon tumors. In this study, we examined the chemopreventive effects of the standardized extract (DA-9601) of Artemisia asiatica that has been used in the traditional herbal medicine for the treatment of inflammatory disorders. Mice fed the chow diet containing 10% DA-9601 for 15 wk following DSS treatment displayed the significantly lower multiplicity of colon tumors. DA-9601 treatment suppressed the expression of COX-2 and iNOS as well as NF-κ B DNA binding in the colonic tissues. It also downregulated the phosphorylation of extracellular, signal-regulated protein kinase and p38 mitogen-activated protein kinase that are upstream of NF-κ B. Furthermore, DA-9601 reduced expression of β-catenin in colonic mucosa of mice challenged with AOM plus DSS.

Inhibitory Effects of 7-Carboxymethyloxy-3′,4′,5-Trimethoxy Flavone (DA-6034) on Helicobacter pylori-Induced NF-κB Activation and iNOS Expression in AGS Cells

Abstract:  The Helicobacter pylori were identified by Marshall and Warren in 1984. H. pylori survive in the forbidding harsh acid environment of the stomach and duodenum by hiding in the mucus layer and neutralizing gastric acid in its local surrounding environment. Multiple lines of evidence suggest that H. pylori infection is one of the primary causes of gastritis and peptic ulcer, which are provoked by oxidative stress and inflammation. More than 50% of the worlds population is infected by this bacterium. The H. pylori‐induced inflammation has been implicated in the pathogenesis and progression of gastric cancer. DA‐6034 (7‐carboxymethyloxy‐3′,4′,5‐trimethoxy flavone) is a synthetic flavonoid known to possess anti‐inflammatory activity. It has been reported that oral administration of DA‐6034 suppresses the inflammatory bowel disease (IBD) in animal models. In this article, we attempted to examine the effect of DA‐6034 on H. pylori‐induced inflammation in human gastric cancer (AGS) cells by targeting NF‐κB and extracellular signal‐regulated kinase (ERK), a representative MAPK.

Beneficial Effect of Korea Red Ginseng on Halitosis; Attenuation of H 2 S Induced Inflammatory Mediators and cystathionine γ-lyase Expression

Halitosis is a generally accepted marker of diseases in the oral cavity and of systemic and gastrointestinal disorders. Based on these authors’ previous findings (that (1) there is a close association between H. pylori infection and halitosis; (2) Korea red ginseng may suppress the colonization of H. pylori, fight H. pylori-induced cytotoxicity, and impose significant anti-inflammatory actions in patients with chronic gastritis; and (3) H. pylori infection is linked with the generation of significant levels of volatile sulfur compounds (VSCs), and the levels of VSCs correlate significantly with H. pylori-associated mucosal damages), in the current study, the authors documented the molecular mechanisms of Korea red ginseng’s efficacy in ameliorating halitosis. When the RAW 264.7 cells were treated with the H₂S releasing compound NaHS, the mRNA expression of cystathionine γ-lyase (CSE), IL-6, COX-2, and iNOS were more significantly induced compared with the vehicle-treated group. The cytoskeletal components of ezrin’s and moesin’s mRNA expressions were elevated by NaHS treatment accompanied by the activation of MAPK, p38, and ERK. Korea red ginseng pretreatment reduced both the NaHS-induced CSE expression and the proinflammatory genes (e.g., IL-6, COX-2, and iNOS) in a concentration-dependent manner. The ERM expression and the phosphorylation of p38 were also significantly reduced by Korea-red-ginseng pretreatment. Overall, Korea red ginseng pretreatment imposed significant anti-inflammatory effects through the downregulation of the NaHS-triggered proinflammatory gene expression, CSE, and ERM mRNA expression. Korea red ginseng could thus be said to be a key remedy of halitosis and to be effective in relieving gastric inflammation.