• Molecular & Cellular Toxicology
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• v.2 no.1
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• pp.15-20
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• 2006

Genistein is a potent, plant-derived isoflavone that displays estrogenic activity at low concentrations but inhibits proliferation at high amounts. However, the molecular mechanism of genistein is not completely understood. In the present study, the biphasic effects (estrogenic and antiestrogenic activity) of genistein on the growth of MCF-7 cells were identified. Genistein within a low range of concentration, $1-10\;{\mu}M$, stimulated proliferation, while $50-100\;{\mu}M$ caused apoptotic cell death. Additionally, genistein at a low concentration induced estrogen receptor (ER)-mediated gene expression and ER phosphorylation. When pre-treated with PD98059, an MEK inhibitor, ER-mediated gene expression and ER phosphorylation by genistein were noticeably increased. However, the increased gene expression and phosphorylation did not enhance cell proliferation. Moreover, it was observed that ER-mediated signaling performs an important role in the MAPK pathway. The proliferation and apoptosis in genistein-treated MCF-7 cells were partially dependent on the Bcl-2 level. The addition of IC1 182, 780, an estrogen receptor antagonist, inhibited Bcl-2 expression induced by genistein. This study suggests that there is a close relationship between Bcl-2 and the ER signaling pathways in MCF-7 cells.

• Molecular & Cellular Toxicology
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• v.2 no.1
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• pp.1-6
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• 2006

Photodynamic therapy (PDT), a newly established treatment for solid tumors, involves the systemic administration of a tumor localizing photosensitizer that is only activated when exposed to light of appropriate wavelength. Photoactivation of photosensitizer in the presence of oxygen results in the formation of highly cytotoxic molecular species, which precipitates necrosis. PDT has now become a promising means for the treatment of cancer due to its specificity, relatively minimal side effects, and inexpensive. However, the application of PDT has been restricted to the treatment of superficial lesions or the use of interstitial light delivery. A single photon generally activates the photochemical reaction in traditional PDT. However the use of multi photon excitation, where two or more photons simultaneously excite a photosensitizer, allows for the use of wavelengths twice as long. Such wavelengths exhibit better transmittance through tissue and thereby deeper penetration is achieved. This paper will review theoretical principles of multi photon excitation, challenges associated with multi photon PDT and update the current and future role of multi photon PDT in cancer.

• Molecular & Cellular Toxicology
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• v.2 no.1
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• pp.60-66
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• 2006

Methylmercury (MeHg), one of the heavy metal compounds, can cause severe damage to the central nervous system in humans. Many reports have shown that MeHg is poisonous to human body through contaminated foods and has released into the environment. Despite many studies on the pathogenesis of MeHg-induced central neuropathy, no useful mechanism of toxicity has been established so far. This study, using of suppression subtractive hybridization (SSH) method, was peformed to identify differentially expressed genes by MeHg in SH-SY5Y human neuroblastoma cell line. We prepared to total RNA from SH-SY5Y cells treated with solvent (DMSO) and $6.25\;{\mu}M\;(IC_{50})$ MeHg and performed forward and reverse SSH. Differentially expressed cDNA clones were screened by dot blot, sequenced and confirmed that individual clones indeed represent differentially expressed genes with real time RT-PCR. These sequences were identified by BLAST homology search to known genes or expressed sequence tags (ESTs). Analysis of these sequences may provide an insight into the biological effects of MeHg in the pathogenesis of neurodegenerative disease and a possibility to develop more efficient and exact monitoring system of heavy metals as ubiquitous environmental pollutants.

• Molecular & Cellular Toxicology
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• v.2 no.1
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• pp.11-14
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• 2006

In this study we attempted to develop a novel genomic method to selectively isolate target functional microbial genomes from environmental samples. For this purpose, stable isotope probing (SIP) was applied in selectively isolating organic pollutant-assimilating populations. When soil microbes were fed with $^{13}C-labeled $ biphenyl, biphenyl-utilizing cells were incorporated with the heavy carbon isotope. The heavy DNA portion was successfully separated by CsCl equilibrium density gradient. And the diversity in the heavy DNA was sufficiently reduced, being suitable for the current DNA microarray techniques to detect biphenyl-utilizing populations in the soil. In addition, we proposed a new way to get more genetic information by combining this SIP method with selective metagenomic approach. The increased selective power of these new DNA isolation methods will be expected to provide a good quality of new genetic information, which, in turn, will result in development of a variety of biomarkers that may be used in assessing ecotoxicology issues including the impacts of organic hazards, and antibiotic-resistant pathogens on human and ecological systems.

• Herbal Formula Science
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• v.30 no.3
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• pp.175-182
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• 2022

Objective : This study aims to investigate the active ingredients and potential mechanisms of the beneficial herb on human cancers such as the liver by employing network pharmacology. Methods : Ingredients and their target information was obtained from various databases such as TM-MC, TTD, and Drugbank. Related protein for liver cancer was retrieved from the Comparative Toxicogenomics Database and literature. A hypergeometric test and gene set enrichment analysis were conducted to evaluate associations between protein targets of red ginseng (Panax ginseng C. A. Meyer) and liver cancer-related proteins and identify related signaling pathways, respectively. Network proximity was employed to identify active ingredients of red ginseng on liver cancer. Results : A compound-target network of red ginseng was constructed, which consisted of 363 edges between 53 ingredients and 121 protein targets. MAPK signaling pathway, PI3K-Akt signaling pathway, p53 signaling pathway, TGF-beta signaling pathway, and cell cycle pathway was significantly associated with protein targets of red ginseng. Network proximity results indicated that Ginsenoside Rg1, Acetic Acid, Ginsenoside Rh2, 20(R)-Ginsenoside Rg3, Notoginsenoside R1, Ginsenoside Rk1, 2-Methylfuran, Hexanal, Ginsenoside Rd, Ginsenoside Rh1 could be active ingredients of red ginseng against liver cancer. Conclusion : This study suggests that network-based approaches could be useful to explore potential mechanisms and active ingredients of red ginseng for liver cancer.

• Molecular & Cellular Toxicology
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• v.1 no.3
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• pp.164-171
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• 2005

Toxicological studies have an object of detecting adverse effects of a chemical on an organism based on observed toxicity marker (i.e., serum biochemical markers and chemical-specific gene expression) or phenotypic outcome. To date, most toxicogenomic studies concentrated on hepatic toxicity. cDNA microarray analysis enable discrimination of the responses in animals exposed to different classes of hepatotoxicants. In an effort to further characterize the mechanisms of 2, 3, 7, 8,-Tetrachlorodibenzo-p-dioxin (TCDD or dioxin)-mediated toxicity, comprehensive temporal-responsive microarray analyses were performed on hepatic tissue from Sprague-Dawley rats treated with TCDD. Hepatic gene expression profiles were monitored using custom DNA chip containing 490 cDNA clones related with toxicology. Gene expression analysis identified 26 features which exhibited a significant change. In this study, we observed that the genes related with oxidative stress in rats exposed to Dioxin, such as CYPIIA3 and glutathione S-transferase, were up-regulated at 24hr after exposure. In this study, we carried out to discover novel evidence for previously unknown gene expression patterns related to mechanism of hepatic toxicity in rats exposed to dioxin, and to elucidate the effects of dioxin on the gene expression after exposure to dioxin.

• Molecular & Cellular Toxicology
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• v.1 no.3
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• pp.149-156
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• 2005

Di (n-ethylhexyl) phthalate (DEHP) is thought to mimic estrogens in their action, and are called endocrine disrupting chemicals. DEHP is used in numerous consumer products, especially those made of flexible polyvinyl chloride and have been reported to be weakly estrogenic. In this study, DEHP were tested for estrogenic properties in vitro models and with microarray analysis. First, the E-screen assay was used to measure the proliferation of DEHP in MCF-7 cells, a human breast cancer cell line. DEHP induced an increase in MCF-7 cell proliferation at concentration of $10^{-4}M$. Second, we carried out a microarray analysis of MCF-7 cells treated with DEHP using human c-DNA microarray including 401 endocrine system related genes. Of the genes analyzed, 60 genes were identified showing significant changes in gene expression resulting from DEHP. Especially, 4 genes were repressed and 4 genes were induced by DEHP compared to $17{\beta}-estradiol$. Among these genes, trefoil factor 3 (intestinal), breast cancer 1, early onset and CYP1B1 are involved in estrogen metabolism and regulation. Therefore it suggests that these genes may be associated with estrogenic effect of the DEHP on transcriptional level. The rationale is that, as gene expression is a sensitive endpoint, alterations of these genes may act as useful biomarkers to define more precisely the nature and level of exposure to kinds of phthalates.

• Molecular & Cellular Toxicology
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• v.1 no.3
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• pp.179-188
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• 2005

To develop the novel anti-allergic drug, many sophoricoside derivatives were synthesized. Among these derivatives, JSH-II-3, VI-3, VII-3, VIII-3, VII-20 and VII-20 (sodium salt) were selected and subjected to high throughput toxicity screening (HTTS) because they revealed strong IL-5 inhibitory activity and limitation of quantity. Single cell gel electrophoresis (Comet) assay, mouse lymphoma thymidine kinase ($tk^{+/-}$) gene assay (MOLY), chromosomal aberration assay in mammalian cells and Ames reverse mutation assay in bacterial system were used as simplified, inexpensive, short-term in vitro screening tests in our laboratory. Through the primary screening using the comet assay, we could choose the first candidates of sophoricoside derivatives with no genotoxic potentials as JSH-VI-3, VII-3, VII-20 and VII-20 (sodium salt). Also JSH-VII-3, VII-20 and VII-20 (sodium salt) are non-mutagenic in MOLY assay, while JSH-II-3 is mutagenic at high concentration with the presence of metabolic activation system in both comet assay and MOLY assay. The selected derivatives (JSH-VI-3, VII-3, VII-20 and VII-20 (sodium salt) are not mutagenic in S. typhimurium TA98 and TA100 strains both in the presence and absence of metabolic activation. From results of chromosomal aberration assay, 6 h treatment of JSH-VI-3, VII-3 and VII-20 (sodium salt) were not revealed clastogenicity both in the presence and absence of S-9 mixture. Therefore, we suggests that JSH-VI-3, VII-3, VII-20 and VII-20 (sodium salt), as the optimal candidates with both no genotoxic potential and IL-5 inhibitory effects must be chosen. To process the development into new anti-inflammatory drug of these derivatives, further investigation will need.

• Molecular & Cellular Toxicology
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• v.1 no.3
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• pp.196-202
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• 2005

Nitric oxide (NO) is a small, diffusible, and highly reactive molecule, which plays dichotomous regulatory roles under physiological and pathological conditions. NO promotes apoptosis in some cells, and inhibits apoptosis in other cells. In the present study, we attempted to characterize the NO signaling pathway and cellular response in PC12 cells treated with cytokines. $IFN{\gamma}\;and\;TNF{\alpha}$ treatment resulted in a synergistic increase of nitrite accumulation, with the induction of inducible nitric oxide synthase (iNOS) in the PC12 cells. Moreover, as nitrite concentration increased, cell viability decreased. In order to explore MAP kinase involvement in nitric oxide production resultant from $IFN{\gamma}\;and\;TNF{\alpha}$ stimulation, we measured the activation of MAP kinase using specific MAP kinase inhibitors. PC12 cells pretreated with SB203580, a p38 MAP kinase-specific inhibitor, resulted in the inhibition of iNOS expression and NO production. However, PD98059, an ERK/MAP kinase-specific inhibitor, was not observed to exert such an effect. In addition, Stat1 activated by $IFN{\gamma}\;and\;TNF{\alpha}$ was interacted with p38 MAPK. These data suggest that p38 MAP kinase mediates cytokine-mediated iNOS expression in the PC12 cells, and Jak/Stat pathway interferes with p38 MAPK signaling pathway.

• Molecular & Cellular Toxicology
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• v.3 no.4
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• pp.320-325
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• 2007

Promoter hypermethylation of the $p16^{INK4a}$ gene was investigated in 52 sets of samples of tumor tissue and adjacent normal tissue from Korean patients with colorectal cancer, using the proposed modified the Real-time PCR/SYBR Green detection method presented in this study. In normal tissue, 29 of 52 patients (56%) were methylated and in tumor tissue, 23 of 52 patients (44%) were methylated. The 34 cases (65.4%) showed a concordant DNA methylation pattern in both normal tissue and tumor tissue. Analyzing the association between the clinicopathologic features and DNA methylation status of the $p16^{INK4a}$ gene, the DNA methylation status according to by Duke's stage was different while other clinicopathological characteristics, including the age, sex, tumor stage, and histologic type of the patient were not found to be correlated with $p16^{INK4a}$ methylation. With multivariate logistic regression, it was observed that the DNA methylation status of $p16^{INK4a}$ gene in normal tissue was correlated with the DNA methylation status of the $p16^{INK4a}$ gene in tumor tissue (P=0.026). According to a Kaplan-Meier survival analysis, a difference in the survival rate by DNA methylation status was found, but it was not significant.