"Molecular & Cellular Toxicology"

Lee, Joohyun;Lee, Eunil;Kwon, Daeho;Lim, Yongchul;Oh, Sangnam;Oh, Minyeong;Hong, Eunyoung

doi: 10.1007/s13273-010-0017-2pmid: N/A

Abstract The 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a well-known carcinogen, however, the biological mechanism of carcinogenesis by TCDD has not been established. Recently, protein arginine methyltransferases (PRMTs) have been identified as secondary transcription co-activators and are proposed to be co-activators of aryl hydrocarbon receptors binding to xenobiotic response elements. Both PRMT1 and PRMT4 were also reported to be involved with carcinogenesis. The aim of this study was to identify cancer-related genes that are regulated by TCDD exposure and the effect of arginine methylation on TCDD toxicity by transfecting human hepatocarcinoma cells with PRMT1 and PRMT4 siRNA. By microarray analysis, 1,461 genes were up-regulated and 1,591 genes were down-regulated by TCDD exposure. Among the 16 up-regulated genes which had functions related to cancer or metastasis, 13 genes were confirmed by quantitative real time RT-PCR: ABCG2, NRP1, SOX5, BIRC3, CD109, CYP1A1, ERBB2, MTA1, FURIN, F3, PIK3R3, NPTN and NTN4. Co-inhibition of PRMT1 and PRMT4 resulted in decreased expression of eight of these genes, MTA1, ERBB2, SOX5, CD109, FURIN, NRP1, PIK3R3 and ABCG2, all of which have been reportedly involved in breast, ovary, prostate and lung cancers, and metastasis.

Kim, Youn-Jung;Yang, Sung Ik;Ryu, Jae-Chun

doi: 10.1007/s13273-010-0018-1pmid: N/A

Abstract Nano-silver (Ag) with antimicrobial activity is by far the most commercialized nano-compound. The hazards associated with human exposure to nanosized-silver should be investigated to facilitate the risk assessment process. Recent studies have shown that inflammatory, oxidative, genotoxic, and cytotoxic consequences are associated with silver particulate exposure, and are inherently linked. In the present study, the cytotoxicity and genotoxicity of nano-silver were investigated using the dye exclusion assay, the comet assay, and the mouse lymphoma thymidine kinase (tk+/−) gene mutation assay (MLA). IC20 values of nano-silver in L5178Y cells were determined the concentration of 3,769.53 μg/mL and 1,796.88 μg/mL with and without S-9, respectively. And in BEAS-2B cell, IC20 values were calculated to 1,171.88 μg/mL and 761.72 μg/mL with and without S-9, respectively. From these results, nano-silver was more cytotoxic in absence of S-9 metabolic activation system and at the BEAS-2B cells. In the comet assay, L5178Y cells and BEAS-2B cells were treated with nano-silver which significantly increased >2-fold tail moment with and without S-9. However, the mutant frequencies in the nano-silver treated L5178Y cells were slightly increased but not significant compared to the vehicle controls with and without S-9. The results of this study indicate that nano-silver can cause primary DNA damage and cytotoxicity but not mutagenicity in cultured mammalian cells.

Cha, Seok Ho;Suh, Chang Kook

doi: 10.1007/s13273-010-0019-0pmid: N/A

Abstract To clarify the effect of a phytochemical, methyl gallate (MG) on a heavy metal (cadmium)-induced renal toxicity, cytotoxicity and the change of heme oxygenase-1 (HO-1) gene expression was studied using cultured mouse renal glomerular mesangial cells (MMC). By employing RT-PCR and Western blotting analysis, we have examined the HO-1 induction in MMCs that were treated with Cd2+ and/or MG. Using MTT assay we have also examined the cytoprotective effect of HO-1 induction against the cytotoxicity caused by toxic dose of Cd2+. In MMCs exposed to Cd2+ and MG, expression of HO-1 (mRNA and protein) was increased in a concentration- and time-dependent manner. The increments of HO-1 mRNA and protein expressions by Cd2+ and MG were inhibited by the treatment of the cells with actinomycin D, an inhibitor of transcription. The decreased viability of the cells by Cd2+ was partially recovered by the treatment of MG and this recovery by the MG was reduced by the treatment of zinc protoporphyrin IX (a HO-1 inhibitor). From these results, methyl gallate might have cytoprotective effect on Cd2+-induced cytotoxicity that is related with heme oxygenase-1 induction.

Kim, Hye-Jeong;Kim, Young-Chul

doi: 10.1007/s13273-010-0020-7pmid: N/A

Abstract This study investigated the effect of Corni Fructus (Cornus officinalis Sieb. et Zucc.) extract on hyperglycemia, renal dysfunction and diabetic nephropathy in db/db mice. Eight weeks old male mice were divided into normal control group (NC), diabetic control group (DC) and Corni Fructus treated diabetic group (DCF). Over an 8-week experimental period, Corni Fructus extract was administered orally at 500 mg/kg BW/day. Final fasting serum glucose level in the DCF group was significantly lower than the DC group by 32% (P<0.05). Urine 24-h volume and urine total protein in the DCF group were significantly lower (P<0.05) than the DC group by 53% and 88%, respectively. The mRNA expression of angiotensin II, collagen I, collagen IV and TGF-β1 in kidneys were significantly lower (P<0.05 or P<0.01) in the DCF group than the DC group by 39%, 42%, 38% and 26%, respectively. In histological staining of kidney tissues, collagen deposition was markedly reduced in the DCF group compared to the DC group. Immunohistochemical staining for TGF-β1 in kidneys of the DCF group was more mildly expressed than the DC group. In conclusion, these results indicate that Corni Fructus can be effective on hyperglycemia, renal dysfunction and diabetic nephropathy in db/db mice.

Lee, Sang-eun;Jang, Ik-soon;Park, Jun-soo;Lee, Ji-Hae;Lee, Seung-Yeul;Baek, So-young;Lee, Seung-hoon;Lee, Hyunah

doi: 10.1007/s13273-010-0021-6pmid: N/A

Abstract Obesity has recently been defined as a chronic inflammatory disease and is considered as a major cause of adult health problems including incurable diseases like diabetes and cancer. In this study, the systemic immunity, including the innate and adaptive immunity parameters, of naturally occurring (leptin receptor mutation) obesity-diabetes mice (db/db) was examined to increase our knowledge of these mice for obesity-related studies. Severe fatty liver with blood engorgement was observed in the db/db mice. Compared to background C57BL/6J mice, the adaptive immunity, as measured by mitogen-induced T and B cell proliferation and cytokine release, was significantly suppressed in db/db mice. However, significant upregulation of innate immune-inflammatory parameters including macrophage function and NK cell activity was observed in db/db mice without external stimulation. These data conclusively confirm the systemic immune-inflammatory micro-environment with suppressed adaptive immunity of db/db mice, which may cause the secondary obesity-related life-threatening diseases like diabetes or cancer.

Park, Mi Seon;Shin, Hyun Suk;Lee, Jehee;Kil, Gyung-Suk;Choi, Cheol Young

doi: 10.1007/s13273-010-0022-5pmid: N/A

Abstract The aim of the present study was to determine whether quercetin, an antioxidant and radical scavenger as natural flavonoid, would be able to offer any protection against cadmium (Cd) toxicity in olive flounder, Paralichthys olivaceus with emphasis on biochemical analysis. Fish were pre-treated with 0% (Diet 1), 0.25% (Diet 2) and 0.5% (Diet 3) quercetin for 30 and 60 day and after that, fish were post-exposed to 10 ppb Cd for 0, 6, 12, 24, and 48 hr. To understand the stress-resistance effect of quercetin, we measured the mRNA expression of metallothionein (MT), glucocorticoid receptor (GR), and level of acetylcholinesterase (AChE) in quercetin-treated flounder exposed to Cd. The MT and GR expression levels were lower in flounder fed Diets 2 and 3 than in those fed Diet 1, and AChE level was higher in flounder fed Diet 2 and 3 than in those fed Diet 1. Plasma cortisol increased in fish fed Diets 1, 2, and 3, but it was lower in fish fed Diets 2 and 3 than in those fed Diet 1. In addition, lipid peroxidation (LPO) levels lower than with Diet 1, which protected the cell membrane. We also investigated the effects of cortisol on stress resistance in vitro. Results showed that the MT and GR expression levels were lower in livers of flounder fed with Diets 2 and 3 than those fed with Diet 1, suggesting that quercetin reduced the stress induced by Cd. These results indicate that quercetin has a stress-resistance effect and acts to maintain physiological homeostasis.

Yoon, Jung Hwan;Song, Jae Hwi;Kang, Young Hwi;Park, Yong Kyu;Zhang, Cao;Nam, Suk Woo;Lee, Jung Young;Park, Won Sang

doi: 10.1007/s13273-010-0023-4pmid: N/A

Abstract Tumor necrosis factors (TNF) regulate the inflammatory response, cell growth and differentiation and its genetic polymorphisms are correlated with various cancer types including colon, and ovarian cancer. To determine whether polymorphisms at TNFA −G308A and TNFB +G252A were associated with a susceptibility to gastric cancer, we investigated the genotype and allele frequencies of these genes in 181 gastric cancer patients and 290 healthy individuals. The polymorphism analysis was performed by amplifying the promoter region of TNF-α for TNFA −308 and the first intron of TNF-β for TNFB +252, digestion with NCO1 restriction enzymes, and then sequencing the products. The frequencies of the genotypes for TNFA −308 were G/G, G/A, and A/A, 93.4% (169/181), 5.0% (9/181) and 1.7% (3/181), respectively, in gastric cancer patients and 88.6% (257/290), 11.4% (33/290) and 0% (0/290), respectively, in the healthy controls. Statistically, there was a significant difference in the genotype frequency of the TNFA −308 between the healthy controls and the gastric cancer patients (P=0.0034). However, genotype and allele frequency for TNFB +252 was not associated with an increased risk of gastric cancer in this population. When stratified by histological subtype of gastric cancer, there was no statistical significance between the risk and the two polymorphisms of TNFA −308 and TNFB +252. Our findings suggest that the TNFA −308 polymorphism of the TNF-α gene may be closely associated with susceptibility to gastric cancer in Korean patients.

Ahn, Joon-Ik;Jeong, Kyung Ji;Ko, Moon-Jeong;Shin, Hee Jung;Kim, Hye Soo;Chung, Hye Joo;Jeong, Ho-Sang

doi: 10.1007/s13273-010-0024-3pmid: N/A

Abstract Epigallocatechin gallate (EGCG), a major type of green tea polyphenol, has been reported to cause hepatotoxicity when used in excess. Micro-RNAs (miRNAs) are small non-coding RNA molecules that functions as negative regulators of gene expression. They play an important role in the regulation of genes involved in the cellular and molecular responses to toxicants. To examine miRNA regulatory effect on global gene expression in EGCG-treated HepG2 cells, we performed pair-wise correlation coefficient analysis on expression levels of 22 miRNA and 27,419 mRNA, and observed negative correlations (r< −0.7) between miRNA and mRNA. We identified a total of 234 negative correlated miRNA-mRNA pairs. Gene Ontology analysis on the miRNA-correlated genes revealed significant enrichment in the several biological processes related to organic acid metabolic process, carboxylic acid metabolic process and cellular protein catabolic process. Connectivity map analysis also revealed that the expression signatures of EGCG were very similar to those of polyphenol gossypol which is hepatotoxic to animal and human.

Hong, Seong Bin;Uhm, Wook Hyun;Joo, Woo Chul;Nam, Moon Suk;Lee, Seoung Woo;Song, Joon Ho

doi: 10.1007/s13273-010-0025-2pmid: N/A

Abstract Alpha-lipoic acid (ALA) is a natural antioxidant that scavenges reactive oxygen species (ROS) and regenerates endogenous antioxidants. In the present study, plasma molecular markers of oxidative stress, inflammatory state, and endothelial cell injury was measured to investigate the effect of simultaneous blocking of both angiotensin (AT) II-and oxidative stress-mediated pathophysiologic pathways during the course of type II diabetic nephropathy in the clinical settings. Sixty-three diabetic subjects have carried out either of 12-month treatment course of AT-II receptor blocker (ARB) alone, ALA alone, or combination of both. Plasma malondialdehyde (MDA) level, a marker for oxidative stress, increased in ARB alone group whereas reduced to significantly lower level in ALA+ ARB combination group. Plasma hs-CRP level, an inflammatory marker, decreased significantly in ARB +ALA group. Plasma thrombomodulin (TM) level, a marker of endothelial cell injury, increased in both ARB and ALA group. Twenty-four hour urinary protein excretion, as a marker of renal injury, decreased in ARB and ARB+ALA group. Finally, renal function was reserved well in ARB+ALA group in compared to others. The combined administration of ALA and ARB additively attenuated or reduced plasma markers of oxidative stress, inflammation and endothelial cell injury for one year. It suggests that the benefits in attenuating atherogenic process and vascular injury retard the progression of renal dysfunction.

Lim, Dong-Jin;Park, Bae Keun;Jang, Won Gu;Lee, Kkot-Nim;Franceschi, Renny;Kim, Sun-Hun;Lee, Shee-Eun;Koh, Jeong-Tae

doi: 10.1007/s13273-010-0026-1pmid: N/A

Abstract A rapamycin (RPM)-inducible fibroblast cell line expressing BMP2, BLK-RapBMP2, was previously developed using a stringent dimerizer-regulated transcription system to achieve more kinetic control of bone morphogenetic protein (BMP) expression for exogenous bone regeneration. This study examined the precise control of BMP2 synthesis and the induction of bone formation using various amounts of cells and rapamycin. The response to the rapamycin analogue (AP21967) caused the BLK-RapBMP2 cells to induce BMP2 expression in a cell amount-dependent manner corresponding to changes in the bone formation components in vitro and in vivo. The administration of rapamycin (1 mg/kg, i.p. for 6 weeks) induced variable ectopic bone formation to diverse number (2−10 × 106) of BLK-RapBMP2 cells in collagen hydrogel implants of a skin pouch in C57BL/6 mice. Microradiographic, biochemical (total calcium and phosphate concentration) and histological analyses suggest that control of the implanted cell number affects the level of rapamycin-induced bone formation. These results suggest that this technical control of BMP2 expression by adjusting the number of cells is a potential factor that might allow more precise control of bone regeneration.