• 대한의생명과학회지
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• 제27권4호
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• pp.329-333
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• 2021

We previously identified that tumor cells genetically modified with a 4-1BBL co-stimulatory molecule had anticancer effects in a CT26 mouse colorectal tumor model. To identify the distinction between immune cells in a mouse tumor model treated with tumor cells genetically modified with 4-1BBL or β-gal, we examined the immune cells in CT26-WT, CT26-βgal, and CT26-4-1BBL tumor bearing mice 21 days after tumor cell administration. The CD8+ T cells population in mice treated with tumor cells genetically modified with 4-1BBL was significantly increased on day 21 compared to that of tumor cells genetically modified with β-gal in the spleen and tumor tissue. The CD4+ T cell population was not different between the two mice groups. The Foxp3+CD25^high CD4 T cell population decreased on day 21 in tumor tissues, but the decrease was not significant. We also found that CD8 T cells had pivotal roles in inhibiting tumor growth by treating mice with ant-CD4 and CD8 antibodies. These results suggest that tumor cells genetically modified with 4-1BBL could inhibit tumor growth by affecting on CD8 T lymphocytes.

• 대한의생명과학회지
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• 제28권4호
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• pp.312-316
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• 2022

We have previously reported that genetically modified tumor cells with 4-1BBL have anti-cancer effects in a CT26 mouse colorectal tumor model. In this study, genetically modified tumor cells with 4-1BBL were evaluated for their potential as candidates for preventive and therapeutic cancer vaccine. To identify the effect of preventive and therapeutic vaccine of genetically modified tumor cells with 4-1BBL, tumor growth pattern of CT26-4-1BBL as a cancer vaccine was examined compared to CT26-beta-gal. In therapeutic vaccination, CT26-WT was inoculated into mice and then vaccinated mice with doxorubicin (Dox)-treated CT26-beta-gal and CT26-4-1BBL (single or three times). Triple vaccination with Dox-treated tumor cell inhibited tumor growth compared to single vaccination. Vaccination with CT26-4-1BBL showed an efficient tumor growth inhibition compared to vaccination with CT26-beta-gal. For preventive vaccination, Dox-treated CT26-beta-gal and CT26-4-1BBL was vaccinated into mice with three times and then administered mice with CT26-WT. Preventive vaccination with CT26-4-1BBL showed no tumor growth. Preventive vaccination with CT26-beta-gal also led to tumor-free mice. These results suggest that genetically modified tumor cells with 4-1BBL can be used as therapeutic or preventive cancer vaccine.

• 한국식품저장유통학회지
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• 제14권6호
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• pp.688-694
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• 2007

To evaluate the human risk of long-term intake of genetically modified (GM) rice, we carried out RT-PCR of housekeeping genes. Housekeeping genes, which show highly uniform expression in living organisms during various stages of development and under different environmental conditions, were normalized by RT-PCR. We assessed the expression of 10 common housekeeping genes (18s rRNA, 25S rRNA, UBC, UBQ5, UBQ10, ACT11, GAPDH, eEF-$1{\alpha}$, ${\beta}$-TUB, GAPDH, ${\beta}$-actin, B2m, G6pd2, Gyk, Gus, Hprt, Cyclophlin A, Tfrc, ${\alpha}$-tubulin and RPL13A) in the liver, stomach, small intestine, large intestine, kidney and spleen of mice fed GM or non-GM rice. We found no significant differences in the expression of housekeeping genes between the two groups of mice.

• 농업과학연구
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• 제48권4호
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• pp.1003-1013
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• 2021

Thioredoxin (TRX) protein is an antioxidant responsible for reducing other proteins by exchanging cysteine thiol-disulfide and is also known for its anti-allergic and anti-aging properties. On the other hand, epidermal growth factor (EGF) is an important material used in the cosmetics industry and an essential protein necessary for dermal wound healing facilitated by the proliferation and migration of keratinocytes. EGF also assists in the formation of granulation tissues and stimulates the motility of fibroblasts. Hence, genetically modified soybeans were developed to overexpress these industrially important proteins for mass production. A single-dose oral-toxicity-based study was conducted to evaluate the potential toxic effects of TRX and EGF proteins, as safety assessments are necessary for the commercial use of seed-specific protein-expressing transgenic soybeans. To achieve this rationale, TRX and EGF proteins were mass purified from recombinant E. coli. The single-dose oral-toxicity tests of the TRX and EGF proteins were carried out in six-week old male and female Institute of Cancer Research (ICR) mice. The initial evaluation of the single-dose TRF and EGF treatments was based on monitoring the toxicity signatures and mortality rates among the mice, and the resultant mortality rates did not show any specific clinical symptoms related to the proteins. Furthermore, no significant differences were observed in the weights between the treatment and control groups of male and female ICR mice. After 14 days of treatment, no differences were observed in the autopsy reports between the various treatment and control groups. These results suggest that the minimum lethal dose of TRX and EGF proteins is higher than the allowed 2,000 mg·kg^-1 limit.

• 대한의생명과학회지
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• 제25권4호
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• pp.372-380
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• 2019

Mice with specific modified genes are useful means of studying development and disease. The CRISPR/Cas9 system is a very powerful and effective tool for generating genetically modified mice in a simple and fast manner. To generate human IgG light kappa constant knock-in mice, we tested by microinjection of a mixture of Cas9 protein, single-guide RNA and target homologous recombinant donor DNA into zygotes. We found that the injection of 10 ng/μL of Cas9 protein and crRNA/tracrRNA, rather than single guide RNA, induced the production of knock-in mice more effectively. Thus, our study provides valuable information that will help to improve the production of knock-in mice and contribute the successful generation of humanized Ab-producing mice in Korea.

• 생명과학회지
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• 제27권2호
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• pp.194-201
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• 2017

유채는 십자화과로 분류되는 유지작물로써 전 세계적으로 재배되는 작물이다. 이전 연구결과에서 가뭄저항성을 증대시키는 것으로 보고된 애기장대의 ${\beta}$-glucosidase 1 (AtBG1) 유전자를 도입함으로써 가뭄저항성 형질전환 유채를 개발하였다. 새로 개발된 형질전환 작물들은 그 이용에 대한 안전성에 대하여 어떠한 정보도 제공되지 않기 때문에 작물의 안정성에 대한 증명이 필수적이다. 이러한 안정성 평가는 작물의 역사적 사용과 과학적 증거를 기초로 한다. 이번 연구에서는 AtBG1이 도입된 형질전환 유채의 급성투여독성시험을 통하여 암수 마우스 각각에서 한계투여 용량을 확인하는 것을 목적으로 하였다. 이를 위해 OECD의 급성독성의 권고안에 따라 AtBG1 단백질을 암수 각각 5마리의 ICR 마우스에 몸무게 1 kg 당 2,000 mg을 부형제에 녹여 강제구강투여 하였다. 투여일부터 14일 동안 운동성, 병리학적 이상, 몸무게를 측정하였고 마지막 14일에는 안락사 후에 부검을 통해 AtBG1 투여군과 비투여군의 차이를 확인하였다. 이상의 실험을 통하여 AtBG1 단백질이 운동성, 병리학적 이상, 몸무게 및 부검 결과에서 대조구와 실험구, 두 그룹간의 특이적인 차이를 보이지 않음을 확인하였다. 또한 AtBG1 단백질은 급성독성의 측면에서 안전한 물질로 판단되며, 한계허용치 용량이 2,000 mg을 상회함을 확인하였다. 따라서, 이는 차후 AtBG1 도입 유채의 인체위해성 평가 자료로 사용될 수 있을 것으로 사료된다.

• Toxicological Research
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• 제26권1호
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• pp.1-8
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• 2010

The process of new drug development consists of several stages; after identifying potential candidate compounds, preclinical studies using animal models link the laboratory and human clinical trials. Among many steps in preclinical studies, toxicology and safety assessments contribute to identify potential adverse events and provide rationale for setting the initial doses in clinical trials. Gene modulation is one of the important tools of modern biology, and is commonly employed to examine the function of genes of interest. Advances in new drug development have been achieved by exploding information on target selection and validation using genetically modified animal models as well as those of cells. In this review, a recent trend of genetically modified methods is discussed with reference to safety assessments, and the exemplary applications of gene-modulating tools to the tests in new drug development were summarized.

• 농업과학연구
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• 제45권2호
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• pp.248-257
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• 2018

Overexpression of AtCYP78A7, a gene encoding a cytochrome P450 protein, has been reported to improve tolerance to drought stress in genetically modified (GM) rice (Oryza sativa L.). The aim of this study was to evaluate the potential allergenicity and acute oral toxicity of the AtCYP78A7 protein expressed in GM rice. Bioinformatics analysis of the amino acid sequence of AtCYP78A7 did not identify any similarities with any known allergens or toxins. It showed that no known allergen had more than a 35% amino acid sequence homology with the AtCYP78A7 protein over an 80 amino acid window or more than 8 consecutive identical amino acids. The gene encoding the AtCYP78A7 protein was cloned in the pGEX-4T-1 vector and expressed in E. coli. Then, the AtCYP78A7 protein was purified and analyzed for acute oral toxicity. The AtCYP78A7 protein was fed at a dose of 2,000 mg/kg body weight in mice, and the changes in mortalities, clinical findings, and body weight were monitored for 14 days after the dosing. Necropsy was carried out on day 14. The protein did not cause any adverse effects when it was orally administered to mice at 2000 mg/kg body weight. These results indicate that the AtCYP78A7 protein expressed in GM rice would not be a potential allergen or toxin.

• 농업과학연구
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• 제43권1호
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• pp.109-115
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• 2016

Silk has had a reputation as a luxurious and sensuous fabric but it is not popular due to the expensive price and poor durability. To develop the silk materials that apply the various industries, the artificially synthesized gene can be introduced into the silkworm and expressed in the silk gland. Transgenic silkworms for the mass production of green fluorescent silks are generated using a fibroin H-chain expression system. For commercial use, safety assessment of the transgenic silkworms is essential. The purpose of this study was to examine the potential acute oral toxicity of EGFP protein expressed in genetically modified (GM) fluorescence silkworm and to obtain the approximative lethal dose in the male and female at 6-weeks ICR mice. EGFP protein was fed at a dose of 2,000 mg/kg body weight in five male or five female mice. Mortalities, clinical findings and body weight changes were monitored for 1, 3, 7, 14 days after dosing. At the end of 14 day observation period, all mice were sacrificed, and the postmortem necropsy were performed. The test group was not observed death case. Also the effect was not admitted by test substance administration in common symptoms, the body weight and postmortem. The results of single-dose oral toxicity test showed that approximative lethal dose of EGFP protein expressed in fluorescence silkworm was considered to exceed the 2,000 mg/kg body weight in both sexes.

• Toxicological Research
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• 제17권
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• pp.167-171
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• 2001

The introduction of genetically modified crops has raised concerns regarding safety issues over the insertion of foreign genes into plant genomes using recombinant DNA technology. Since 1991 in Japan, 29 foods and 6 food additives have been evaluated, based on the "Guideline for Safety Assessment", before these foods were marketed. The MHW, however, decided that safety assessment of such foods and food additives should be legally imposed. because soon such foods and food additives are expected to circulate globally and a new system for assessing safety of such foods and food additives at a pre-market stage is necessary, in order to avoid the distribution of any genetically modified foods that have had no safety assessment. The MHW published relevant announcements to amend existing regulations on 1 May 2000. "Standards for safety assessment of seed plant" is established based on a concept of substantial equivalence, and applicable to the products which are regarded as equivalent to the existing products used as foods and food additives. The characterization of the food products entails consideration of the molecular characterization. phenotypic and compositional characteristics, key nutrients and toxicants, and toxicity and allergenicity of the introduced proteins, and if there are indications of unintended effects of the modification, whether further safety testing (animal studies etc.) is needed should be considered. Safety and wholesomeness studies with whole foods should be care fully designed in order to avoid nutritional imbalances causing artifacts and uninterpretable results as was the case of Dr. Pusztaiis report. A case study of genetically modified soybeans (glyphosate-tolerant soybeans) on the immune system of rats and mice is shown. Chemical compositions were also compared with those of the non-GM soybeans. The studies failed to detect any differences in immuno-toxic activity.muno-toxic activity.