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author:("Kang, Boo hon")
1.  Evaluation of General Toxicity and Genotoxicity of the Silkworm Extract Powder 
Toxicological Research  2013;29(4):263-278.
The silkworm extract powder contain 1-deoxynojirimycin (DNJ), a potent α-glycosidase inhibitor, has therapeutic potency against diabetes mellitus. Therefore, natural products containing DNJ from mulberry leaves and silkworm are consumed as health functional food. The present study was performed to evaluate the safety of the silkworm extract powder, a health food which containing the DNJ. The repeated toxicity studies and gentic toxicity studies of the silkworm extract powder were performed to obtain the data for new functional food approval in MFDS. The safety was evaluated by a single-dose oral toxicity study and a 90 day repeated-dose oral toxicity study in Sprague-Dawley rats. The silkworm extract powder was also evaluated for its mutagenic potential in a battery of genetic toxicity test: in vitro bacterial reverse mutation assay, in vitro chromosomal aberration test, and in vivo mouse bone marrow micronucleus assay. The results of the genetic toxicology assays were negative in all of the assays. The approximate lethal dose in single oral dose toxicity study was considered to be higher than 5000 mg/kg in rats. In the 90 day study, the dose levels were wet at 0, 500, 1000, 2000 mg/kg/day, and 10 animals/sex/dose were treated with oral gavage. The parameters that were monitored were clinical signs, body weights, food and water consumptions, ophthalmic examination, urinalysis, hematology, serum biochemistry, necropsy findings, organ weights, and histopathological examination. No adverse effects were observed after the 90 day administration of the silkworm extract powder. The No-Observed-Adverse-Effect-Level (NOAEL) of silkworm extract powder in the 90 day study was 2000 mg/kg/day in both sexes, and no target organ was identified.
PMCID: PMC3936179  PMID: 24578797
Single oral dose toxicity; 90 day repeated dose toxicity; Genotoxicity; Silkworm extract powder
2.  PPARβ/δ promotes HRAS-induced senescence and tumor suppression by potentiating p-ERK and repressing p-AKT signaling 
Oncogene  2013;33(46):5348-5359.
Peroxisome proliferator-activated receptor-β/δ (PPARβ/δ) inhibits skin tumorigenesis through mechanisms that may be dependent on HRAS signaling. The present study examined the hypothesis that PPARβ/δ promotes HRAS-induced senescence resulting in suppression of tumorigenesis. PPARβ/δ expression increased p-ERK and decreased p-AKT activity. Increased p-ERK activity results from the dampened HRAS-induced negative feedback response mediated in part through transcriptional upregulation of RAS guanyl-releasing protein 1 (RASGRP1) by PPARβ/δ. Decreased p-AKT activity results from repression of integrin-linked kinase (ILK) and phosphoinositide dependent protein kinase-1 (PDPK1) expression. Decreased p-AKT activity in turn promotes cellular senescence through upregulation of p53 and p27 expression. Both over-expression of RASGRP1 and shRNA-mediated knockdown of ILK partially restore cellular senescence in Pparβ/δ-null cells. Higher PPARβ/δ expression is also correlated with increased senescence observed in human benign neurofibromas and colon adenoma lesions in vivo. These results demonstrate that PPARβ/δ promotes senescence to inhibit tumorigenesis and provide new mechanistic insights into HRAS-induced cellular senescence.
PMCID: PMC4017002  PMID: 24213576
peroxisome proliferator-activated receptor-β/δ; HRAS-induced senescence; mechanisms of senescence; inhibition of tumorigenesis
3.  Activation of peroxisome proliferator-activated receptor-β/δ (PPARβ/δ) inhibits human breast cancer cell line tumorigenicity 
Molecular cancer therapeutics  2014;13(4):1008-1017.
The effect of activation and over-expression of the nuclear receptor PPARβ/δ in human MDA-MB-231 (ER−) and MCF7 (ER+) breast cancer cell lines was examined. Target gene induction by ligand activation of PPARβ/δ was increased by over-expression of PPARβ/δ compared to controls. Over-expression of PPARβ/δ caused a decrease in cell proliferation in MCF7 and MDA-MB-231 cells compared to controls while ligand activation of PPARβ/δ further inhibited proliferation of MCF7 but not MDA-MB-231 cells. Over-expression and/or ligand activation of PPARβ/δ in MDA-MB-231 or MCF7 cells had no effect on experimental apoptosis. Decreased clonogenicity was observed in both MDA-MB-231 and MCF7 over-expressing PPARβ/δ in response to ligand activation of PPARβ/δ as compared to controls. Ectopic xenografts developed from MDA-MB-231 and MCF7 cells over-expressing PPARβ/δ were significantly smaller and ligand activation of PPARβ/δ caused an even greater reduction in tumor volume as compared to controls. Interestingly, the decrease in MDA-MB-231 tumor size after over-expressing PPARβ/δ and ligand activation of PPARβ/δ correlated with increased necrosis. These data show that ligand activation and/or over-expression of PPARβ/δ in two human breast cancer cell lines inhibits relative breast cancer tumorigenicity and provide further support for the development of ligands for PPARβ/δ to specifically inhibit breast carcinogenesis. These new cell-based models will be invaluable tools for delineating the role of PPARβ/δ in breast cancer and evaluating the effects of PPARβ/δ agonists.
PMCID: PMC3981956  PMID: 24464939
PPARβ/δ; breast cancer; cell proliferation; xenografts
4.  Toxicity of colloidal silica nanoparticles administered orally for 90 days in rats 
International Journal of Nanomedicine  2014;9(Suppl 2):67-78.
This study was undertaken to investigate the potential toxicity and establish the no observed adverse effect level (NOAEL) and target organ(s) of negatively charged colloidal silica particles of different sizes, ie, SiO2EN20(−) (20 nm) or SiO2EN100(−) 2(100 nm), administered by gavage in Sprague-Dawley rats. After verification of the physicochemical properties of the SiO2 particles to be tested, a preliminary dose range-finding study and 90-day repeated dose study were conducted according to the Organisation for Economic Cooperation and Development test guideline. Based on the results of the 14-day dose range-finding study, a high dose was determined to be 2,000 mg/kg, and middle and low doses were set at 1,000 and 500 mg/kg, respectively. In the 90-day toxicity study, there were no animal deaths in relation to administration of SiO2 particles of either size. In addition, no treatment-related clinical changes or histopathological findings were observed in any of the experimental groups. Moreover, no difference in toxic effects from chronic exposure to SiO2EN20(−)(20 nm) or SiO2EN100(−) (100 nm) was observed. The results of this study indicate that the NOAEL for SiO2EN20(−) and SiO2 EN100(−) would most likely be 2,000 mg/kg, and no target organ was identified in rats of either sex.
PMCID: PMC4279771  PMID: 25565827
silica nanoparticles; particle size; 90-day oral dose toxicity; no observed adverse effect level
5.  Toxicity of 100 nm zinc oxide nanoparticles: a report of 90-day repeated oral administration in Sprague Dawley rats 
International Journal of Nanomedicine  2014;9(Suppl 2):109-126.
Nanoparticles (NPs) are used commercially in health and fitness fields, but information about the toxicity and mechanisms underlying the toxic effects of NPs is still very limited. The aim of this study is to investigate the toxic effect(s) of 100 nm negatively (ZnOAE100[−]) or positively (ZnOAE100[+]) charged zinc oxide (ZnO) NPs administered by gavage in Sprague Dawley rats, to establish a no observed adverse effect level, and to identify target organ(s). After verification of the primary particle size, morphology, hydrodynamic size, and zeta potential of each test article, we performed a 90-day study according to Organisation for Economic Co-operation and Development test guideline 408. For the 90-day study, the high dose was set at 500 mg/kg and the middle and low doses were set at 125 mg/kg and 31.25 mg/kg, respectively. Both ZnO NPs had significant changes in hematological and blood biochemical analysis, which could correlate with anemia-related parameters, in the 500 mg/kg groups of both sexes. Histopathological examination showed significant adverse effects (by both test articles) in the stomach, pancreas, eye, and prostate gland tissues, but the particle charge did not affect the tendency or the degree of the lesions. We speculate that this inflammatory damage might result from continuous irritation caused by both test articles. Therefore, the target organs for both ZnOAE100(−) and ZnOAE100(+) are considered to be the stomach, pancreas, eye, and prostate gland. Also, the no observed adverse effect level for both test articles was identified as 31.25 mg/kg for both sexes, because the adverse effects were observed at all doses greater than 125 mg/kg.
PMCID: PMC4279774  PMID: 25565830
zinc oxide nanoparticles; surface charge; 90-day oral dose toxicity; no observed adverse effect level
6.  PPARβ/δ modulates ethanol-induced hepatic effects by decreasing pyridoxal kinase activity 
Toxicology  2013;311(3):10.1016/j.tox.2013.07.002.
Because of the significant morbidity and lethality caused by alcoholic liver disease (ALD), there remains a need to elucidate the regulatory mechanisms that can be targeted to prevent and treat ALD. Towards this goal, minimally invasive biomarker discovery represents an outstanding approach for these purposes. The mechanisms underlying ALD include hepatic lipid accumulation. As the peroxisome proliferator-activated receptor-β/δ (PPARβ/δ) has been shown to inhibit steatosis, the present study examined the role of PPARβ/δ in ALD coupling metabolomic, biochemical and molecular biological analyses. Wild-type and Pparβ/δ-null mice were fed either a control or 4% ethanol diet and examined after 4–7 months of treatment. Ethanol fed Pparβ/δ-null mice exhibited steatosis after short-term treatment compared to controls, the latter effect appeared to be due to increased activity of sterol regulatory element binding protein 1c (SREBP1c). The wild-type and Pparβ/δ-null mice fed the control diet showed clear differences in their urinary metabolomic profiles. In particular, metabolites associated with arginine and proline metabolism, and glycerolipid metabolism, were markedly different between genotypes suggesting a constitutive role for PPARβ/δ in the metabolism of these amino acids. Interestingly, urinary excretion of taurine was present in ethanol-fed wild-type mice but markedly lower in similarly treated Pparβ/δ-null mice. Evidence suggests that PPARβ/δ modulates pyridoxal kinase activity by altering Km, consistent with the observed decreased in urinary taurine excretion. These data collectively suggest that PPARβ/δ prevents ethanol-induced hepatic effects by inhibiting hepatic lipogenesis, modulation of amino acid metabolism, and altering pyridoxal kinase activity.
PMCID: PMC3811069  PMID: 23851158
metabolomics; alcoholic liver disease; peroxisome proliferator-activated receptor-β/δ (PPARβ/δ); pyridoxal kinase
7.  A Spontaneous Epithelial-Myoepithelial Carcinoma of the Submandibular Gland in a Sprague-Dawley Rat 
The present report describes a rare case of spontaneous tumor of the salivary gland in a male Sprague-Dawley rat. The clinically confirmed mass rapidly developed in the cervical region between 19 and 21 weeks of age, and the animal was subsequently euthanized. At necropsy, a well-circumscribed nodule approximately 7 × 6 cm in diameter was found at the site of the salivary gland. The cut surface of the nodule was lobulated and soft and had a pinkish tan fish-flesh appearance. One large cyst (approximately 3 × 2 cm in size) containing reddish fluid was also present in the nodule. Histopathologically, the tumor, with a partially lobulated structure, was surrounded by a thin fibrous capsule. The majority of tumor cells formed a diffuse solid sheet structure that mainly consisted of small ovoid or spindle-shaped cells. In the tumor periphery, some cells were arranged in nest-like structures. Small duct-like structures lined with a monolayer of cuboidal epithelial cells resembling an intercalated duct or large polygonal clear cells with a myoepithelial component were also observed. Mitotic figures and necrotic foci were frequently observed in solid areas. Immunohistochemically, the tumor cells were positive for cytokeratin, epithelial membrane antigen, vimentin, p63, α-smooth muscle actin and calponin. The cells were negative for calcitonin, synaptophysin and chromogranin A. On the basis of these findings, the tumor was diagnosed as an epithelial-myoepithelial carcinoma originating from the luminal epithelial cells and myoepithelial cells in the submandibular gland.
PMCID: PMC3620217  PMID: 23723571
epithelial-myoepithelial carcinoma; immunohistochemical features; Sprague-Dawley rat; submandibular gland
8.  3,5,5-Trimethyl-Hexanoyl-Ferrocene Diet Protects Mice from Moderate Transient Acetaminophen-Induced Hepatotoxicity 
Toxicological Sciences  2011;124(2):348-358.
Acetaminophen (APAP) overdose is the most frequent cause of adult acute liver failure. Susceptibility or resistance to APAP toxicity is most likely accounted for by the interplay of several factors. One factor important in multiple different chronic liver diseases that may play a role in APAP toxicity is elevated hepatic iron. Hereditary hemochromatosis is traditionally associated with hepatic iron overload. However, varying degrees of elevated hepatic iron stores observed in chronic hepatitis C and B, alcoholic liver disease and nonalcoholic fatty liver disease also have clinical relevance. We employed an animal model in which mice are fed a 3,5,5-trimethyl-hexanoyl-ferrocene (TMHF)-supplemented diet to evaluate the effect of elevated hepatic iron on APAP hepatotoxicity. Three hundred milligrams per kilogram APAP was chosen because this dosage induces hepatotoxicity but is not lethal. Since both excess iron and APAP induce oxidative stress and mitochondrial dysfunction, we hypothesized that the TMHF diet would enhance APAP hepatotoxicity. The results were the opposite. Centrilobular vacuolation/necrosis, APAP adducts, nitrotyrosine adducts, and a spike in serum alanine aminotransferase, which were observed in control mice treated with APAP, were not observed in TMHF-fed mice treated with APAP. Further analysis showed that the levels of CYP2E1 and CYP1A2 were not significantly different in TMHF-treated compared with control mice. However, the magnitude of depletion of glutathione following APAP treatment was considerably less in TMHF-treated mice than in mice fed a control diet. We conclude that a TMHF diet protects mice from moderate transient APAP-induced hepatotoxicity prior to the formation of APAP adducts, and one contributing mechanism is reduction in glutathione depletion.
PMCID: PMC3247805  PMID: 21908766
hepatic iron overload; acetaminophen; hepatotoxicity; glutathione; CYP2E1; CYP1A2
9.  Chemoprevention of chemically-induced skin tumorigenesis by ligand activation of peroxisome proliferator-activated receptor-β/α (PPARβ/α) and inhibition of cyclooxygenase 2 (COX2) 
Molecular cancer therapeutics  2010;9(12):3267-3277.
Ligand activation of peroxisome proliferator-activated receptor-β/δ (PPARβ/δ) and inhibition of cyclooxygenase-2 (COX2) activity by non-steroidal anti-inflammatory drugs (NSAID) can both attenuate skin tumorigenesis. The present study examined the hypothesis that combining ligand activation of PPARβ/δ with inhibition of COX2 activity will increase the efficacy of chemoprevention of chemically-induced skin tumorigenesis over that observed with either approach alone. To test this hypothesis, wild-type and Pparβ/δ-null mice were initiated with 7, 12-dimethylbenz[a]anthracene (DMBA), topically treated with 12-O-tetradecanoylphorbol-13-acetate (TPA) to promote tumorigenesis, and then immediately treated with topical application of the PPARβ/δ ligand GW0742, dietary administration of the COX2 inhibitor nimesulide, or both GW0742 and nimesulide. Ligand activation of PPARβ/δ with GW0742 caused a PPARβ/δ-dependent delay in the onset of tumor formation. Nimesulide also delayed the onset of tumor formation and caused inhibition of tumor multiplicity (46%) in wild-type mice but not in Pparβ/δ-null mice. Combining ligand activation of PPARβ/δ with dietary nimesulide resulted in a further decrease of tumor multiplicity (58%) in wild-type mice but not in Pparβ/δ-null mice. Biochemical and molecular analysis of skin and tumor samples demonstrate that these effects were due to modulation of terminal differentiation, attenuation of inflammatory signaling and induction of apoptosis, through both PPARβ/δ-dependent and PPARβ/δ-independent mechanisms. Increased levels and activity of PPARβ/δ by nimesulide was also observed. These studies support the hypothesis that combining ligand activation of PPARβ/δ with inhibition of COX2 activity increases the efficacy of preventing chemically-induced skin tumorigenesis as compared to either approach alone.
PMCID: PMC3058401  PMID: 21159610
peroxisome proliferator-activated receptor-β/δ; skin cancer; nonsteroidal anti-inflammatory drugs; chemoprevention; nuclear receptor
10.  Ligand activation of peroxisome proliferator-activated receptor β/δ (PPARβ/δ) inhibits chemically induced skin tumorigenesis 
Carcinogenesis  2008;29(12):2406-2414.
Peroxisome proliferator-activated receptor (PPAR)β/δ-null mice exhibit enhanced tumorigenesis in a two-stage chemical carcinogenesis model as compared with wild-type mice. Previous work showed that ligand activation of PPARβ/δ induces terminal differentiation and inhibits proliferation of primary keratinocytes, and this effect does not occur in the absence of PPARβ/δ expression. In the present studies, the effect of ligand activation of PPARβ/δ on skin tumorigenesis was examined using both in vivo and ex vivo skin carcinogenesis models. Inhibition of chemically induced skin tumorigenesis was observed in wild-type mice administered GW0742, and this effect was likely the result of ligand-induced terminal differentiation and inhibition of replicative DNA synthesis. These effects were not found in similarly treated PPARβ/δ-null mice. Ligand activation of PPARβ/δ also inhibited cell proliferation and induced terminal differentiation in initiated/neoplastic keratinocyte cell lines representing different stages of skin carcinogenesis. These studies suggest that topical administration of PPARβ/δ ligands may be useful as both a chemopreventive and/or a chemotherapeutic approach to inhibit skin cancer.
PMCID: PMC2722866  PMID: 18799709
11.  Ligand Activation of Peroxisome Proliferator–Activated Receptor β/δ (PPARβ/δ) Attenuates Carbon Tetrachloride Hepatotoxicity by Downregulating Proinflammatory Gene Expression 
Toxicological Sciences  2008;105(2):418-428.
Peroxisome proliferator–activated receptor (PPAR) β/δ–null mice exhibit exacerbated hepatotoxicity in response to administration of carbon tetrachloride (CCl4). To determine whether ligand activation of the receptor protects against chemical toxicity in the liver, wild-type and PPARβ/δ-null mice were administered CCl4 with or without coadministration of the highly specific PPARβ/δ ligand GW0742. Biomarkers of liver toxicity, including serum alanine aminotransferase (ALT) and hepatic tumor necrosis factor (TNF) α mRNA, were significantly higher in CCl4-treated PPARβ/δ-null mice compared to wild-type mice. Hepatic expression of TNF-like weak inducer of apoptosis receptor (TWEAKr) and S100 calcium–binding protein A6 (S100A6/calcyclin), genes involved in nuclear factor kappa B signaling, was higher in the CCl4-treated PPARβ/δ-null mice compared to wild-type mice. GW0742 treatment resulted in reduced serum ALT concentration and lower expression of CCl4-induced TNF-α, S100A6, monocyte chemoattractant protein-1 (MCP1), and TWEAKr in wild-type mice, and these effects were not observed in PPARβ/δ-null mice. Expression of TNF-α was higher in PPARβ/δ-null primary hepatocytes in response to interleukin-1β treatment compared to wild-type hepatocytes, but GW0742 did not significantly modulate TNF-α expression in hepatocytes from either genotype. While PPARβ/δ-null hepatic stellate exhibited higher rates of proliferation compared to wild-type cells, GW0742 did not affect α-smooth muscle actin expression in these cells. Combined, these findings demonstrate that ligand activation of PPARβ/δ protects against chemically induced hepatotoxicity by downregulating expression of proinflammatory genes. Hepatocytes and hepatic stellate cells do not appear to directly mediate the inhibitory effects of ligand activation of PPARβ/δ in liver, suggesting the involvement of paracrine and autocrine events mediated by hepatic cells.
PMCID: PMC2527639  PMID: 18622026
peroxisome proliferator–activated receptors; hepatotoxicity; inflammation
12.  Strain-specific requirement for eosinophils in the recruitment of T cells to the lung during the development of allergic asthma 
The Journal of Experimental Medicine  2008;205(6):1285-1292.
Eosinophils have been implicated as playing a major role in allergic airway responses. However, the importance of these cells to the development of this disease has remained ambiguous despite many studies, partly because of lack of appropriate model systems. In this study, using transgenic murine models, we more clearly delineate a role for eosinophils in asthma. We report that, in contrast to results obtained on a BALB/c background, eosinophil-deficient C57BL/6 ΔdblGATA mice (eosinophil-null mice via the ΔDblGATA1 mutation) have reduced airway hyperresponsiveness, and cytokine production of interleukin (IL)-4, -5, and -13 in ovalbumin-induced allergic airway inflammation. This was caused by reduced T cell recruitment into the lung, as these mouse lungs had reduced expression of CCL7/MCP-3, CC11/eotaxin-1, and CCL24/eotaxin-2. Transferring eosinophils into these eosinophil-deficient mice and, more importantly, delivery of CCL11/eotaxin-1 into the lung during the development of this disease rescued lung T cell infiltration and airway inflammation when delivered together with allergen. These studies indicate that on the C57BL/6 background, eosinophils are integral to the development of airway allergic responses by modulating chemokine and/or cytokine production in the lung, leading to T cell recruitment.
PMCID: PMC2413027  PMID: 18490489

Results 1-12 (12)