• Journal of Microbiology and Biotechnology
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• 제28권4호
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• pp.645-651
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• 2018

The carcinogenicity of chemicals in the environment is a major concern. Recently, numerous studies have attempted to develop methods for predicting carcinogenicity, including rodent and cell-based approaches. However, rodent carcinogenicity tests for evaluating the carcinogenic potential of a chemical to humans are time-consuming and costly. This study focused on the development of an alternative method for predicting carcinogenicity using quantitative PCR (qPCR) and colon cancer stem cells. A toxicogenomic method, mRNA profiling, is useful for predicting carcinogenicity. Using microarray analysis, we optimized 16 predictive gene sets from five carcinogens (azoxymethane, 3,2'-dimethyl-4-aminobiphenyl, N-ethyl-n-nitrosourea, metronidazole, 4-(n-methyl-n-nitrosamino)-1-(3-pyridyl)-1-butanone) used to treat colon cancer stem cell samples. The 16 genes were evaluated by qPCR using 23 positive and negative carcinogens in colon cancer stem cells. Among them, six genes could differentiate between positive and negative carcinogens with a p-value of ${\leq}0.05$. Our qPCR-based prediction system for colon carcinogenesis using colon cancer stem cells is cost- and time-efficient. Thus, this qPCR-based prediction system is an alternative to in vivo carcinogenicity screening assays.

• Toxicological Research
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• 제28권1호
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• pp.39-49
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• 2012

We investigated the effect of zinc on the formation of colonic aberrant crypt foci induced by azoxymethane (AOM) followed by dextran sodium sulfate (DSS) in mice with high iron diet (HFe; 450 ppm iron). Sixweek old ICR mice were fed on high iron diets with combination of three different levels of zinc in diets, low-zinc (LZn; 0.01 ppm), medium-zinc (MZn; 0.1 ppm), and high-zinc (HZn; 1 ppm) for 12 weeks. Animals were received weekly intraperitoneal injections of AOM (10 mg/kg B.W. in saline) for 3 weeks followed by 2% DSS (molecular weight 36,000~50,000) in the drinking water for a week. To confirm the iron storage in the body, the hepatic iron concentration has been determine chemically and compared with histological assessment visualized by Prussian blue reaction. Aberrant crypt (AC) and aberrant crypt foci (ACF) were analyzed in the colonic mucosa of mouse fed high dietary iron. Superoxide dismutase (SOD) activity and thiobarbituric acid-reactive substances (TBARS) level were also investigated. Apoptosis in the preneoplastic lesion was determined by terminal deoxynucleotidyl transferase-mediated dUTP nickend labeling (TUNEL). In addition, immunohistochemistry of ${\beta}$-catenin was also performed on the mucous membrane of colon. The number of large ACF (${\geq}4$ AC/ACF), which possess greater tumorigenic potential, was significantly lower in MZn and HZn groups compared with LZn group. Cytosolic SOD activity in the liver was significantly higher in HZn group compared with LZn group. Hepatic MDA level was decreased significantly in HZn group compared with MZn and LZn groups. Apoptotic index was significantly higher in HZn group. Taken together, these findings indicate that dietary zinc might exert a protective effect against colonic preneoplastic lesion induced by AOM/DSS in ICR mice with high iron status, and suggest that dietary supplement of zinc might play a role in suppressing colon carcinogenesis in mice.

• Journal of Nutrition and Health
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• 제51권1호
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• pp.14-22
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• 2018

본 연구는 LUT이 고지방식이로 비만이 유도된 C57BL/6 마우스의 대장암 발생에 미치는 영향을 분석하기 위해 실험동물을 각 10마리씩 정상식이 (ND)군, 고지방식이 (HFD)군, HFD + 0.0025% LUT 보충 (HFD LL)군, 그리고 HFD + 0.005% LUT 보충 (HFD HL)군의 4군으로 분류하였다. 각 실험군은 AOM을 1회 복강 주사하고 AOM 투여 1주일 후 총 3 cycle의 1 ~ 2% 농도의 DSS를 음용수로 공급하여 대장암을 유발하였다. 실험식이는 AOM 발암시점부터 총 11주간 급여하였다. 연구결과, 군간 식이섭취량의 차이는 없었으나 HFD 급여군에서 체중과 식이효율의 유의적인 증가가 나타났으며 HFD군과 비교했을 때 LUT 보충에 따른 체중의 변화는 없었다. 그러나 LUT 보충은 ND군에 비해 HFD군에서 나타난 대장 무게/길이 비, 대장종양 수, 혈장 $TNF-{\alpha}$ 농도, 대장 iNOS와 COX-2 발현을 유의적으로 감소시켰으며 그 효과는 HFD HL군이 HFD LL군보다 높았다. 이러한 결과는 체중조절과는 별개로 LUT이 고지방식이에 의한 대장의 염증반응 억제를 통하여 비만과 연관된 대장암 발생을 억제할 수 있음을 제시하며 향후 비만에 의한 인슐린 저항성 및 adipokine 분비, 그리고 장내 균총 변화에 따른 대장 점막세포 증식과 대장암 발생에 LUT이 어떤 영향을 미치는지에 대한 연구를 더 깊이 있게 수행한다면 비만으로 인한 대장암 발생에 LUT이 효과적인 화학적 예방 (chemoprevention)제로 활용될 수 있을 것으로 기대한다.

• Journal of Veterinary Science
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• 제23권5호
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• pp.74.1-74.16
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• 2022

Background: Previous studies have presented evidence to support the significant association between red meat intake and colon cancer, suggesting that heme iron plays a key role in colon carcinogenesis. Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, exhibits anti-oxidative and anti-cancer effects. However, the effect of EGCG on red meat-associated colon carcinogenesis is not well understood. Objectives: We aimed to investigate the regulatory effects of hemin and EGCG on colon carcinogenesis and the underlying mechanism of action. Methods: Hemin and EGCG were treated in Caco2 cells to perform the water-soluble tetrazolium salt-1 assay, lactate dehydrogenase release assay, reactive oxygen species (ROS) detection assay, real-time quantitative polymerase chain reaction and western blot. We investigated the regulatory effects of hemin and EGCG on an azoxymethane (AOM) and dextran sodium sulfate (DSS)-induced colon carcinogenesis mouse model. Results: In Caco2 cells, hemin increased cell proliferation and the expression of cell cycle regulatory proteins, and ROS levels. EGCG suppressed hemin-induced cell proliferation and cell cycle regulatory protein expression as well as mitochondrial ROS accumulation. Hemin increased nuclear factor erythroid-2-related factor 2 (Nrf2) expression, but decreased Keap1 expression. EGCG enhanced hemin-induced Nrf2 and antioxidant gene expression. Nrf2 inhibitor reversed EGCG reduced cell proliferation and cell cycle regulatory protein expression. In AOM/DSS mice, hemin treatment induced hyperplastic changes in colon tissues, inhibited by EGCG supplementation. EGCG reduced the hemin-induced numbers of total aberrant crypts and malondialdehyde concentration in the AOM/DSS model. Conclusions: We demonstrated that EGCG reduced hemin-induced proliferation and colon carcinogenesis through Nrf2-inhibited mitochondrial ROS accumulation.