• The Korean Journal of Physiology and Pharmacology
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• v.18 no.1
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• pp.25-32
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• 2014

Nitric oxide (NO) is recognized as a mediator and regulator of inflammatory responses. NO is produced by nitric oxide synthase (NOS), and NOS is abundantly expressed in the human dental pulp cells (HDPCs). NO produced by NOS can be cytotoxic at higher concentrations to HDPCs. However, the mechanism by which this cytotoxic pathway is activated in cells exposed to NO is not known. The purpose of this study was to elucidate the NO-induced cytotoxic mechanism in HDPCs. Sodium nitroprusside (SNP), a NO donor, reduced the viability of HDPCs in a dose- and time-dependent manner. We investigated the in vitro effects of nitric oxide on apoptosis of cultured HDPCs. Cells showed typical apoptotic morphology after exposure to SNP. Besides, the number of Annexin V positive cells was increased among the SNP-treated HDPCs. SNP enhanced the production of reactive oxygen species (ROS), and N-acetylcysteine (NAC) ameliorated the decrement of cell viability induced by SNP. However, a soluble guanylate cyclase inhibitor (ODQ) did not inhibited the decrement of cell viability induced by SNP. SNP increased cytochrome c release from the mitochondria to the cytosol and the ratio of Bax/Bcl-2 expression levels. Moreover, SNP-treated HDPCs elevated activities of caspase-3 and caspase-9. While pretreatment with inhibitors of caspase (z-VAD-fmk, z-DEVD-fmk) reversed the NO-induced apoptosis of HDPCs. From these results, it can be suggested that NO induces apoptosis of HDPCs through the mitochondria-dependent pathway mediated by ROS and Bcl-2 family, but not by the cyclic GMP pathway.

• Tuberculosis and Respiratory Diseases
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• v.62 no.4
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• pp.314-317
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• 2007

The Inhalation of certain freshly formed metal oxides can cause metal fume fever, which is an acute, self-limiting, flu-like illness. The most common cause of this syndrome is the inhalation of zinc oxide. The inhalation of zinc oxide can lead to tracheobronchiolitis, chemical pulmonary edema or to respiratory failure and acute respiratory distress syndrome(ARDS). We encountered a 43-years-old man who developed severe dyspnea after inhaling of zinc oxide while working for 5 hours in a closed space. He was diagnosed with ARDS and was treated successfully with glucocorticoid. We report a case of ARDS caused by the inhalation of zinc fumes.

• Korean journal of food and cookery science
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• v.26 no.6
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• pp.804-810
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• 2010

Sulforphane (SF) is a family of biologically active compound that is distributed widely in broccoli. Although studies in rodents have shown that these compounds are effective and versatile inhibitors of tumorigenesis, the role of dietary SF in protection against human cancers remains to be established. The objective of this study was to explore the quantitative relationship between the dietary intake of cruciferous vegetables and urinary excretion of SF. The effects of dietary broccoli on the body's ability to detoxify were studied in six male subjects between the ages of 22~30 years. Study included administering a glucosinolate-free diet for 8 days (control period). The broccoli diet was further subdivided into two periods; 250 g broccoli was fed per day during the first three days and 500 g broccoli was fed per day during the latter three days. After an 8-day washout period, a second experiment was conducted. The same protocol was used with the exception that uncooked broccoli was consumed. Urinary SF mercapturate was measured to determine the bioavailability of broccoli. The linear trend for mercapturate excretion was dose-dependent, resulting in 3.8- and 1.9-fold increase by the third and six days, respectively, compared to the control. Lower amount of SF-NAC conjugate was detected in cooked broccoli compared to fresh broccoli suggesting cooking may have caused a significant loss in glucosinolates in cruciferous vegetables. Therefore, SF can be used as a biomarker for intake of cruciferous vegetables.

• Korean Journal of Food Science and Technology
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• v.43 no.6
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• pp.754-759
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• 2011

Zinc protoporphyrin (ZnPP) is produced endogenously during heme metabolism and treated in cells as a heme oxygenase inhibitor. In the present study, the effects of ZnPP on the color response of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, a commonly-used method for analyzing cell viability, were investigated. ZnPP induced rapid decolorizaion of MTT formazan under light; the degradation rates were 10- and 20- folds faster in the presence of 5 and $10{\mu}M$ ZnPP, respectively. Methylene blue (MB), another type of photosensitizer, also accelerated degradation of formazan under light. Butylated hyroxytoluene did not inhibit ZnPP- or MB-induced formazan degradation. The color degradation of formazan dye was signficantly delayed in the presence of N-acetylcysteine or ${\beta}$-carotene. The present results suggest that certain photosensitizing compounds may affect the color and stability of MTT formazan, which should be carefully considered when conducting the MTT assay.

• Oncology Letters
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• v.42 no.4
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• pp.1621-1630
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• 2019

One million females are diagnosed worldwide every year with breast cancer, and the mortality rate of these patients remains high. Several treatments, including surgery, are available for breast cancer. β-Lapachone (β-Lap), a natural quinone compound, has been developed for cancer treatment due to its strong cytotoxic effect through its action on NAD(P)H:quinone oxidoreductase 1 (NQO1)-dependent activity. However, the mechanism in regards to how β-Lap induces cytotoxicity in breast cancer cells is still elusive. In the present study, we showed that β-Lap induced apoptotic cell death via activation of protein kinase A (PKA) in NQO1-overexpressing MDA-MB-231 human breast cancer cells. This PKA-dependent cell death was observed solely in NQO1-overexpressing 231 cells via the high production of reactive oxygen species (ROS). Cell survival of antioxidant [N-acetylcysteine (NAC)]-treated NQO1-overexpressing 231 cells was significantly recovered, and NQO1-negative 231 cells did not respond to β-Lap. Antiapoptotic proteins such as Bcl2 and Bcl-xL were decreased, while proapoptotic proteins, including cytochrome c, activation of caspase-3, and cleavage of PARP were increased after β-Lap treatment of NQO1-overexpressing 231 cells. Furthermore, PKA activators, forskolin or dibutyryl-cAMP, an analog of cAMP, aggravated the β-Lap-induced apoptotic cell death by decreasing antiapoptotic proteins and further activating proapoptotic proteins in NQO1-positive 231 cells. Treatment with a PKA inhibiter, H89, significantly increased cell viability even in NQO1-overexpressing cells treated with β-Lap. These data showed that β-Lap activated PKA via ROS accumulation, subsequently leading to apoptotic cell death in NQO1-positive breast cancer cells.

• Tuberculosis and Respiratory Diseases
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• v.59 no.1
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• pp.30-38
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• 2005

Background : Arsenic trioxide ($As_2O_3$) has been used to treat acute promyelocytic leukemia, and it induces apoptosis in a variety of solid tumor cell lines including non-small cell lung cancer cells. However, nonsteroidal antiinflammatory drugs (NSAID) can enhance tumor response to chemotherapeutic drugs or radiation. It was previously demonstrated that a combination treatment with $As_2O_3$ and sulindac induces the apoptosis of NCI-H157 human lung carcinoma cells by activating the caspase cascade. This study aimed to determine if a combination treatment augmented its apoptotic potential through other pathways except for the activation of the caspase cascade. Material and Methods : The NCI-H157 cells were treated with $As_2O_3$, sulindac and antioxidants such as glutathione (GSH) and N-acetylcysteine (NAC). The cell viability was measured by a MTT assay, and the level of intracellular hydrogen peroxide ($H_2O_2$) generation was monitored fluorimetrically using a scopoletin-horse radish peroxidase (HRP) assay. Western blotting and mitochondrial membrane potential transition analysis were performed in order to define the mechanical basis of apoptosis. Results : The viability of the cells was decreased by a combination treatment of $As_2O_3$ and sulindac, and the cells were protected using antioxidants in a dose-dependent manner. The increased $H_2O_2$ generation by the combination treatment was inhibited by antioxidants. The combination treatment induced changes in the mitochondrial transmembrane potential as well as the expression of the Bcl-2 family proteins, and increased cytochrome c release into the cytosol. However, the antioxidants inhibited the effects of the combination treatment. Conclusion : Combination treatment with $As_2O_3$ and sulindac induces apoptosis in NCI-H157 human lung carcinoma cells via ROS generation with a mitochondrial dysfunction.

• Journal of Life Science
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• v.33 no.2
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• pp.129-137
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• 2023

Reactive oxygen species (ROS) play an essential role in a variety of cellular physiological phenomena. The present study assessed the signaling axis that mediates the lysophosphatidic acid (LPA)-induced migration of SKOV-3 cells. Insulin-like growth factor-1 (IGF-1) stimulated SKOV-3 cell migration in a time- and dose-dependent manner. Similarly, LPA stimulated SKOV-3 cell migration and the phosphorylation of Akt in a time- and dose-dependent manner. The pharmacological inhibition of LPA receptors (LPA₁/LPA₃) significantly suppressed LPA-induced SKOV-3 cell migration. However, IGF-1-induced SKOV-3 cell migration was not affected by the inhibition of LPA1 and LPA3. Pharmacological inhibition of phosphoinositide 3-kinase (PI3K) or Rho-associated kinase (ROCK) significantly suppressed LPA-induced migration, whereas the inhibition of MAPK kinase (MEK) had no effect. Inhibition of PI3K or ROCK completely suppressed LPA-induced ROS generation, and suppression of nicotinamide adenine dinucleotide phosphate oxidase (NOX) or chelation of ROS by N-acetylcysteine (NAC) blocked LPA-induced SKOV-3 cell migration. LPA-induced ROS generation was suppressed by silencing Rictor or Akt1 but not Raptor or Akt2. Silencing Rictor or Akt1 significantly suppressed LPA-induced SKOV-3 cell migration, whereas silencing Raptor or Akt2 had no effect. Finally, the overexpression of the constitutively active form Akt1 (CA-Akt1) significantly enhanced the LPA-induced migration of SKOV-3 cells. Given these results, we suggest that LPA stimulates SKOV-3 cell migration by ROS generation, which is mediated by the mTORC2/Akt1/NOX signaling axis.