• Bulletin of the Korean Chemical Society
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• v.13 no.5
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• pp.565-570
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• 1992

The 1,5-sigmatropic rearrangements involving group (X) migration in ${\omega}$(X)-substituted 1,3-pentadiene, $C^1H_2=C^2H-C^3H=C^4H-C^5H_2-X$, where X = H, $CH_3$, $BH_2$, $NH_2$, OH or F, are investigated MO theoretically using the AM1 method. For the migrating groups without lone pair electrons, X = H, $CH_3$, or $BH_2$, the suprafacial pathway is favored, whereas for the migrating groups with lone pair electrons participating in the TS, $X=NH_2$, OH, or F, the antarafacial pathway is favored electronically. However excessive steric inhibition in the antarafacial TS for $X=NH_2$ leads to subjacent orbital controlled suprafacial process. The antarafacial shift of F is relatively disfavored compared to that of OH due to smaller orbital overlap and larger interfrontier energy gap in the TS.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.9
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• pp.1354-1361
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• 2015

The complement system is a part of the natural immune regulation mechanism against invading pathogens. Complement activation from three different pathways (classical, lectin, and alternative) leads to the formation of C5-convertase, an enzyme for cleavage of C5 into C5a and C5b, followed by C6, C7, C8, and C9 in membrane attack complex. The C9 is the last complement component of the terminal lytic pathway, which plays an important role in lysis of the target cells depending on its self-polymerization to form transmembrane channels. To address the association of C9 with traits related to disease resistance, the complete porcine C9 cDNA was comparatively sequenced to detect single nucleotide polymorphisms (SNPs) in pigs of the breeds Hampshire (HS), Duroc (DU), Berlin miniature pig (BMP), German Landrace (LR), Pietrain (PIE), and Muong Khuong (Vietnamese potbelly pig). Genotyping was performed in 417 $F_2$ animals of a resource population (DUMI: $DU{\times}BMP$) that were vaccinated with Mycoplasma hyopneumoniae, Aujeszky diseases virus and porcine respiratory and reproductive syndrome virus at 6, 14 and 16 weeks of age, respectively. Two SNPs were detected within the third exon. One of them has an amino acid substitution. The European porcine breeds (LR and PIE) show higher allele frequency of these SNPs than Vietnamese porcine breed (MK). Association of the substitution SNP with hemolytic complement activity indicated statistically significant differences between genotypes in the classical pathway but not in the alternative pathway. The interactions between eight time points of measurement of complement activity before and after vaccinations and genotypes were significantly different. The difference in hemolytic complement activity in the both pathways depends on genotype, kind of vaccine, age and the interaction to the other complement components. These results promote the porcine C9 (pC9) as a candidate gene to improve general animal health in the future.

• Molecules and Cells
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• v.26 no.5
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• pp.462-467
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• 2008

TPA is known to cooperate with an activated Ras oncogene in the transformation of rodent fibroblasts, but the biochemical mechanisms responsible for this effect have not been established. In the present study we used c-fos promoter-luciferase constructs as reporters, in transient transfection assays, in NIH3T3 cells to assess the mechanism of this cooperation. We found a marked synergistic interaction between TPA and a transfected v-Ha-ras oncogene in the activation of c-fos promoter and SRE. SRE has binding sites for TCF and SRF. A dominant-negative Ras (ras-N17) inhibited the TPA-Ras synergy by blocking the PKC-MAPK-TCF pathway. Dominant-negative RhoA and Rac1 (but not Cdc42Hs) inhibited the TPA-Ras synergy by blocking the Ras-Rho-SRF signaling pathway. Constitutively active $PKC{\alpha}$ and $PKC{\varepsilon}$ showed synergy with v-Ras. These results suggest that the activation of two distinct pathways such as Ras-Raf-ERK-TCF pathway and Rho-SRF pathway are responsible for the induction of c-fos by TPA and Ras in mitogenic signaling pathways.

• Archives of Pharmacal Research
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• v.26 no.8
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• pp.631-637
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• 2003

Chloroquine has been used for many decades in the prophylaxis and treatment of malaria. It is metabolized in humans through the N-dealkylation pathway, to desethylchloroquine (DCQ) and bisdesethylchloroquine (BDCQ), by cytochrome P450 (CYP). However, until recently, no data are available on the metabolic pathway of chloroquine. Therefore, the metabolic pathway of chloroquine was evaluated using human liver microsomes and cDNA-expressed CYPs. Chloroquine is mainly metabolized to DCQ, and its Eadie-Hofstee plots were biphasic, indicating the involvement of multiple enzymes, with apparent $K_m and V_{max}$ values of 0.21 mM and 1.02 nmol/min/mg protein 3.43 mM and 10.47 nmol/min/mg protein for high and low affinity components, respectively. Of the cDNA-expressing CYPs examined, CYP1A2, 2C8, 2C19, 2D6 and 3A4/5 exhibited significant DCQ formation. A study using chemical inhibitors showed only quercetin (a CYP2C8 inhibitor) and ketoconazole (a CYP3A4/5 inhibitor) inhibited the DCQ formation. In addition, the DCQ formation significantly correlated with the CYP3A4/5-catalyzed midazolam 1-hydroxylation (r=0.868) and CYP2C8-catalyzed paclitaxel 6$\alpha$-hydroxylation (r = 0.900). In conclusion, the results of the present study demonstrated that CYP2C8 and CYP3A4/5 are the major enzymes responsible for the chloroquine N-deethylation to DCQ in human liver microsomes.

• Molecules and Cells
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• v.26 no.4
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• pp.344-349
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• 2008

5-Fluorouracil (5-FU), a pyrimidine antagonist, has a long history in cancer treatment. The targeted pyrimidine biosynthesis pathway includes dihydropyrimidine dehydrogenase (DPD), which converts 5-FU to an inactive metabolite, and thymidylate synthase (TS), which is a major target of 5-FU. Using Caenorhabditis elegans as a model system to study the functional and resistance mechanisms of anti-cancer drugs, we examined these two genes in order to determine the extent of molecular conservation between C. elegans and humans. Overexpression of the worm DPD and TS homologs (DPYD-1 and Y110A7A.4, respectively) suppressed germ cell death following 5-FU exposure. In addition, DPYD-1 depletion by RNAi resulted in 5-FU sensitivity, while treatment with Y110A7A.4 RNAi and 5-FU resulted in similar patterns of embryonic death. Thus, the pathway of 5-FU function appears to be highly conserved between C. elegans and humans at the molecular level.

• Horticultural Science & Technology
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• v.28 no.5
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• pp.750-756
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• 2010

This study was performed to investigate the role of phytohormones in the bulbing of garlic in order to assess the yield and quality. The effect on endogenous plant hormones such as gibberellin (GA) content was also examined during growth stage i.e. clove differentiation to bulbing in garlic. More than 18 gibberellins in garlic were identified with extensive gas chromatograph-mass spectrometry-selected ion monitoring (GC-MS-SIM) quantitative analysis. The results showed that GAs were biosynthesized by both non C-13 hydroxylation pathway (NCH) and early C-13 hydroxylation pathway (ECH) in garlic plant. It was also revealed that NCH pathway leading to synthesis of bioactive $GA_4$ was the more prominent GA biosynthesis pathway than ECH pathway in which bioactive $GA_1$ was synthesized. Total GAs level was gradually increased from clove differentiation to bulbing and later decreased, which portrays the active role of GA in differentiation. The biosynthesis ratio of bioactive $GA_4$ and $GA_1$ concentration was similar to that of total GAs content, which was closely related with bulb development in garlic.

• Journal of Acupuncture Research
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• v.18 no.4
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• pp.101-115
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• 2001

Objective : To characterize the antitumorigenic potential of Apamin, one of the major components of bee venom, its effects on cell proliferation and the mitogen-activated protein kinase (MAPK) signal transduction pathway were characterized using the human melanoma cell line SK-MEL-2. Methods & Results : Cell counting analysis for cell death demonstrated that consistent with a previous results, SK-MEL-2 cells treated with $0.5-2.0{\mu}g/ml$ of Apamin showed no recognizable cytotoxic effect whereas detectable induction of cell death was identified at concentrations over $5.0{\mu}g/ml$. [3H]thymidine incorporation assay for cell proliferation demonstrated that DNA replication of SK-MEL-2 cells is inhibited by Apamin in a dose- and time-dependent manner. To explore whether Apamin-induced growth suppression is associated with the MAPK signaling pathway, phosphorylation of Erk, a function mediator of MAPK growth-stimulating signal, was examined Western blot assay using a phospho-specific Erkl/2 antibody. A significant increase of Erkl/2 phosphorylation level was observed in Apamin-treated cells compared with untreated control cells. Qantitative RT-PCR analysis revealed that Apamin inhibit expression of MAPK downstream genes such as c-Jun, c-Fos, and cyclin D1 but not expression of MAPK pathway component genes including Ha-Ras, c-Raf-1, MEK1, and Erk. Conclusion : It is strongly suggested that the antitumorigenic activity of Apamin might result in part from its inhibitory effect on the MAPK signaling pathway in human melanoma cells SK-MEL-2.

• Biomolecules & Therapeutics
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• v.26 no.3
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• pp.313-321
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• 2018

Anti-cancer drug resistance is a major problem in colorectal cancer (CRC) research. Although several studies have revealed the mechanism of cancer drug resistance, molecular targets for chemotherapeutic combinations remain elusive. To address this issue, we focused on the expression of cellular prion protein ($PrP^C$) in 5-FU-resistant CRC cells. In 5-FU-resistant CRC cells, $PrP^C$ expression is significantly increased, compared with that in normal CRC cells. In the presence of 5-FU, $PrP^C$ increased CRC cell survival and proliferation by maintaining the activation of the PI3K-Akt signaling pathway and the expression of cell cycle-associated proteins, including cyclin E, CDK2, cyclin D1, and CDK4. In addition, $PrP^C$ inhibited the activation of the stress-associated proteins p38, JNK, and p53. Moreover, after treatment of 5-FU-resistant CRC cells with 5-FU, silencing of $PrP^C$ triggered apoptosis via the activation of caspase-3. These results indicate that $PrP^C$ plays a key role in CRC drug resistance. The novel strategy of combining chemotherapy with $PrP^C$ targeting may yield efficacious treatments of colorectal cancer.

• BMB Reports
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• v.38 no.5
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• pp.619-623
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• 2005

The efficacy of chemotherapeutic agents on tumor cells has been shown to be modulated by tumor suppressor gene p53 and its target genes such as Bcl-2 family members (Bax, Noxa, and PUMA). However, various chemotherapeutic agents can induce cell death in tumor cells that do not express the functional p53, suggesting that some chemotherapeutic agents may induce cell death in a p53-independent pathway. Here we showed that etoposide can induce the similar degree of cell death in p53-deficient HCT 116 cells, whereas 5'-FU-mediated cell death is strongly dependent on the existence of functional p53 in HCT 116 cells. Further, we provide the evidence that etoposide can induce the cytochrome c release from isolated mitochondria, and etoposide-induced cytochrome c release is not accompanied with the large amplitude swelling of mitochondria. These data suggest that etoposide can directly induce the mitochondrial dysfunction irrespective of p53 status, and it may, at least in part, account for the p53-independent pathway in cell death induced by chemotherapeutic agents.

• Journal of Microbiology and Biotechnology
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• v.9 no.6
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• pp.804-810
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• 1999

There is a possibility that carvone, a monoterpene from spearmint (Mentha spicata), could induce the bph degradative pathway and genes in Alcaligenes eutrophus H850, which is a known Gram-negative PCB degrader with a broad substrate specificity that was thoroughly investigated with Arthrobacter sp. BIB, a Gram-positive PCB degrader. The strains BIB and H850 were unable to utilize and grow on the plant terpene [(R)-(-)-carvone] (50ppm) to be recognized as a sole carbon source. Nevertheless, the carvone did induce 2,3-dihydroxybiphenyl 1,2-dioxygenase (encoded by bphC) in the strain B lB, as observed by a resting cell assay that monitors accumulation of a yellow meta ring fission product from 4,4'-dichlorobiphenyl (DCBp). The monoterpene, however, did not appear to induce the meta cleavage pathway in the strain H850. Instead, an assumption was made that the strain might be using an alternative pathway, probably the ortho-cleavage pathway. A reverse transcription (RT)-PCR system, utilizing primers designed from a conserved region of the bphC gene of Arthrobacter sp. M5, was employed to verify the occurrence of the alternative pathway. A successful amplification (182bp) of mRNA transcribed from the N-terminal region of the bphC gene was accomplished in H850 cells induced by carvone (50ppm) as well as in biphenyl-growth cells. It is, therefore, likely that H850 possesses a specific PCB degradation pathway and hence a different substrate specificity compared with B1B. This study will contribute to an elucidation of the dynamic aspects of PCB bioremediation in terms of roles played by PCB degraders and plant terpenes as natural inducer substrates that are ubiquitous and environmentally compatible.