Biomedical subjects

Hye-Sook Kim

Publications and source records attributed to Hye-Sook Kim.

At least 19 recordsLinked to original sources

PubMed2006

Proteome and transcriptome analysis of 5-fluoro-2'-deoxyuridine-induced cell death mechanisms.

5-Fluoro-2'-deoxyuridine (FUdR) inhibits thymidylate synthase. The inhibition of thymidylate synthase causes an imbalance of intracellular deoxyribonucleoside triphosphate (dNTP) pools which subsequently induced cell death. We have been investigated the molecular mechanisms of cell death in mouse mammary tumor FM3A cells, F28-7 strain and its mutant F28-7-A strain, after treated with FUdR. We have previously been reported that F28-7 strain induced DNA cleavage into chromosomal sized fragments and subsequently develop necrosis, but F28-7-A strain induced DNA cleavage into oligonucleosomal sized fragments and subsequently develop apoptosis after treated with FUdR. In this report, in order to understand the molecular mechanisms of regulate of two differential cell death necrosis and apoptosis, we identify cell death regulator by using proteome and transcriptome analysis. When compared with the proteome from F28-7 strain and F28-7-A strain, it was found that ten proteins were increased and six proteins were decreased in F28-7-A strain. Furthermore, transcriptome analysis shows that 127 genes were increased and 181 genes were decreased in F28-7-A strain. These differentially expressed proteins and genes were involved in various cellular processes such as cell cycle regulation, apoptosis, proliferation, and differentiation. These two techniques clarified numerous features in F28-7 strain and F28-7-A strain. Our results revealed that numerous features indicated the coordinated regulation of molecular networks from various aspects of necrosis or apoptosis at the proteome and transcriptome levels.

Animals↗

PubMed2006

An apoptotic pathway of 3'-Ethynylcytidine(ECyd) involving the inhibition of RNA synthesis mediated by RNase L.

RNase L is an endoribonuclease that requires 2'-5' oligoadenylate to cleave single-stranded RNA. Although the antiviral effects of RNase L are well known because of its viral RNA degradation activity recently but it has been suggested that RNase L is concerned in mitochondrial-caspase dependent apoptotic signaling pathway induced by a number of anticancer agents. Moreover, it has variety of functions including translation and transcription of proteins. In this report, we found that 1-(3-C-ethynyl-beta-D-ribo-pentofuranosyl) cytosine (ECyd), which inhibits RNA synthesis through competitive inhibition of RNA polymerase I induced 28S rRNA fragmentation. The cleavage pattern of rRNA induced by ECyd was similar and the cleavage sites were identical to those cleaved by RNase L. Additionaly, apoptosis induced by ECyd was elevated following the protein expression of RNase L in the tumor cells when treated with IFN-alpha2a which was known to induce RNase L expression. To identify the role of RNase L in apoptosis induced by ECyd, we detected the decreased level of RNase L by several folds in the tumor cell lines through a small interfering RNA (siRNA). These results indicated that RNase L might integrate apoptotic signals induced by ECyd and provide the possibility to be a novel clinical target for cancer chemotherapy.

Antineoplastic Agents↗

PubMed2005

Synthesis of novel siRNAs having thymidine dimers consisting of a carbamate or a urea linkage at their 3' overhang regions and their ability to suppress human RNase L protein expression.

In order to examine the effect of modifications at the 3' overhang regions of short interfering RNAs (siRNAs) on their gene-silencing activities, we designed and synthesized novel siRNAs having thymidine dimers consisting of a carbamate or a urea linkage at their 3' overhang regions. Suppression of human RNase L protein expression by these siRNAs was analyzed by immunoblot with RNase L-specific antibody. It was found that, at 24 h post-transfection, the modified siRNAs having the thymidine dimers with the carbamate and urea linkage suppress the protein expression 78 and 37 times more efficiently than that with the natural phosphodiester linkage, respectively. Furthermore, the siRNA containing the carbamate linkage was 37 times more resistant to nucleolytic degradation by snake venom phosphodiesterase than the siRNA consisting of the natural phosphodiester linkage. Thus, the RNA duplexes having the thymidine dimers with the carbamate or urea linkage at their 3' overhang regions will be promising candidates for novel siRNA molecules to down-regulate protein expression.

Carbamates↗

PubMed2005

Synthesis of 5'-methylenearisteromycin and its 2-fluoro derivative with potent antimalarial activity due to inhibition of the parasite S-adenosylhomocysteine hydrolase.

5'-methylenearisteromycin 5 and its 2-fluoro derivative 6, which were designed as antimalarial agents because of their AdoHcy hydrolase inhibition, were synthesized from D-ribose, using a stereoselective intramolecular radical cyclization as the key step to construct the carbocyclic structure. These compounds were evaluated as AdoHcy hydrolase inhibitors with the recombinant human and malarial parasite enzymes. Although 5 and 6 were both potent inhibitors of the malarial parasite AdoHcy hydrolase, the 2-fluoro derivative 6 proved to be superior due to its lower inhibitory effect on the human enzyme. In addition, 6 was identified as a potent antimalarial agent using an in vitro assay system with Plasmodium falciparum.

Adenosine↗

PubMed2005

Association of HLA-DR, -DQ genotype and CTLA-4 gene polymorphism with Graves' disease in Japanese children.

OBJECTIVE: Childhood onset Graves' disease (GD) has been documented to be clinically distinct from adult onset GD, and an association with the genes encoding HLA and CTLA-4 (cytotoxic T lymphocyte antigen-4) has been reported in both Caucasian and Japanese adult GD patients. The aim of this study was to determine whether HLA-DR, -DQ and CTLA-4 are associated with childhood onset GD in Japanese individuals. METHODS: We investigated the genotype of HLA class II (DRB1, DQB1) and the A/G transition polymorphism of CTLA-4 exon 1 position 49 in 43 GD patients and in healthy controls for comparison. The CTLA-4 alleles were identified by the polymerase chain reaction (PCR) of genomic DNA and restriction fragment-length polymorphism analysis (PCR-RFLP) with Ita1. RESULTS: The frequency of both HLA-DRB1*0405 and DQB1*0401 was increased in the patient group (DRB1*0405: 26.7%, p < 0.001; DQB1*0401: 25.6%, p < 0.005) compared with the controls. Patients with GD had a significantly lower frequency of the AA genotype of CTLA-4 than the controls, but there was no difference in allele frequency between the G and A allele. CONCLUSIONS: the association of HLA-DRB1 and DQB1 genotype with susceptibility to childhood onset GD differs from that in adult onset GD, whereas the association between CTLA-4 gene polymorphism and childhood onset GD is similar to that in adult onset GD in Japanese individuals, but the association is weak.

Adolescent↗

PubMed2005

Inhibitory mechanisms of 1-(3-C-ethynyl-beta-D-ribopentofuranosyl)uracil (EUrd) on RNA synthesis.

1-(3-C-ethynyl-beta-D-ribo-pentofuranosyl)uracil (EUrd) is an antimetabolite that strongly inhibits RNA synthesis and shows a broad antitumor activity in vitro and in vivo. In mouse mammary tumor FM3A cells, EUrd is sequentially phosphorylated to its 5'-triphosphate, EUTP, a major metabolite, and the RNA synthesis is inhibited proportionally to its intracellular accumulation. To study the inhibitory mechanisms of EUrd on RNA synthesis, we have performed the kinetic analysis of EUTP on RNA polymerization using isolated nuclei RNA synthesis was inhibited competitively by EUTP. The inhibition constant, Ki was much lower than the Km value of UTP (Ki value of EUTP, 84 nM; Km value of UTP, 13 microM), indicating that the high affinity of EUTP could contribute to the specific inhibition of RNA synthesis. As a result of RNA synthesis inhibition, EUrd, but not ara-C, induced shrinkage of nucleoli, which are the main sites for RNA synthesis in FM3A cells. Thus, the strong affinity of EUTP to RNA polymerase and specific inhibition of RNA synthesis could contribute to its antitumor effect. EUrd is expected to be a new antitumor drug, possessing a strong inhibitory effect on the synthesis of RNA.

Animals↗

PubMed2005

Sequence analysis of the 5'-flanking regions of human dihydropyrimidine dehydrogenase gene: identification of a new polymorphism related with effects of 5-fluorouracil.

Dihydropyrimidine dehydrogenase (DPD), known as a rate-limiting metabolic enzyme in the catabolism of 5-fluorouracil (5-FU), degrades more than about 80% of the administered 5-FU in human liver. Since it was reported that the anticancer effects of 5-FU were observed in cancer patients with lower DPD activities, many attempts have been conducted to anticipate the expected anticancer effects of 5-FU based on expression of intracanceral DPD. It have been reported that 39 different mutations and polymorphisms in the coding regions of DPD genes have been identified; however, there is no report on polymorphisms in the 5'-flanking region of DPD genes. We investigated polymorphisms in the 5'-flanking regions (3,058 bp), which are considered to control expression of DPD genes, in genomic DNA extracted from 37 kinds of human cancer cells. As the results, out of 37 cancer cells subjected to analysis, DLD- 7 cells had C insertion and 7 strains G deletion, which were hetelozygote. No significant relationship was identified between the DPD activity and the expression levels of DPD mRNA in examined 10 kinds of human cancer cells. However, in DLD-1 cells, which have C-insertion polymorphism in 5'-flanking region of DPD gene, the DPD activity was below detection limit (< or = 0.5 pmol/min/mg protein). Furthermore, 50% of cytosine residue on the CpG site generated by the C insertion was methylated at the 5 position. In this study, we have identified novel polymorphism possibly related the cytotoxicity of 5-FU in the 5'-flanking region of DPD gene. It is suggested that newly identified polymorphism of DPD gene might affect transcription of DPD, thereby providing influence on the clinical outcome of cancer patients treated with 5-FU.

Antimetabolites, Antineoplastic↗

PubMed2005

Gastrodia elata blume and an active component, p-hydroxybenzyl alcohol reduce focal ischemic brain injury through antioxidant related gene expressions.

Ischaemic stroke is a leading cause of death and long-lasting disability. Gastrodia elata blume (GEB) is a Chinese herb that is widely used to treat convulsive disorders, such as epilepsy, and p-hydroxybenzyl alcohol (HBA) is the active ingredient in GEB. The present study was conducted to evaluate the effects of GEB and HBA on the brain damage and transcriptional levels of Protein disulfide isomerase (PDI) and 1-Cys peroxiredoxin (1-Cys Prx) genes known to play a role in antioxidant systems after transient focal ischemia in the rat brain. Focal ischemia was induced in rats by middle cerebral artery occlusion (MCAO). All animals underwent ischemia for 1 h, followed by 24 h of reperfusion. Coronal brain slices were stained with 2,3,5-triphenyltetrazolium chloride or total RNA was extracted for the analysis of gene expression. Histopathologic analysis revealed a significant (p<0.05) decrease in infarct size in the ipsilateral brain with GEB extracts or HBA. Moreover, the levels of PDI and 1-Cys Prx transcription were significantly increased in the GEB extract- or HBA-treated group compared with the untreated group (p<0.05). This study therefore indicated that GEB and HBA provide neuroprotection by preventing brain damage through the increased expression of genes encoding antioxidant proteins after transient focal cerebral ischemia and may be effective as neuroprotective agents at the cellular and molecular levels in the brain.

Animals↗

PubMed2005

Synthesis and evaluation of beta-carbolinium cations as new antimalarial agents based on pi-delocalized lipophilic cation (DLC) hypothesis.

Several beta-carbolines including naturally occurring substances and their corresponding cationic derivatives were synthesized and evaluated for antimalarial (antiplasmodial) activity in vitro and in vivo. A tetracyclic carbolinium salt was elucidated for antileishmanial and antitrypanosomal activities in vitro as well as antiplasmodial activity. Quarternary carbolinium cations showed much higher potencies in vitro than electronically neutral beta-carbolines and a good correlation was observed between pi-delocalized lipophilic cationic (DLC) structure and antimalarial efficacy. beta-Carbolinium compounds exhibit medium suppressive activity in vivo against rodent malaria.

Animals↗

PubMed2005

Synthesis and biological activity of fatty acid derivatives of quinine.

Derivatives of quinine with fatty acids including polyunsaturated fatty acids were prepared. They showed moderate antimalarial activity as compared with quinine itself using Plasmodium falciparum. The activities were not dependent on whether the fatty acyl group was saturated or unsaturated. On the other hand, the derivatives showed significantly higher cytotoxicity against a mammary tumor cell line FM3A than quinine itself. Calculating from these data, an acetyl derivative of quinine with the shortest acyl group was found to give the highest selectivity.

Animals↗

PubMed2004

Duffy antigen is important for the lethal effect of the lethal strain of Plasmodium yoelii 17XL.

We studied the potential role of the Duffy antigen and glycophorin A as receptors for rodent malaria parasite invasion of erythrocytes. Parasitemia increased exponentially after infection with Plasmodium berghei NK65, P. chabaudi, and P. vinckei in Duffy antigen knockout, glycophorin A knockout, and wild-type mice, indicating that the Duffy antigen and glycophorin A are not essential for these malaria parasites. However, parasitemia of the Duffy antigen knockout mice infected with P. yoelii 17XL remained constant from day 5 to 14 after infection, and then decreased, resulting in autotherapy. The treatment of P. yoelii 17XL-infected Duffy antigen knockout mice with anti-CD4 antibody increased the parasitemia 15 days after infection and the mice eventually died, indicating that CD-4-positive cells play an important role in the clearance of P. yoelii 17XL at the late stage of the infection.

Animals↗

PubMed2004

Pi-delocalized beta-carbolinium cations as potential antimalarials.

Several beta-carboline compounds including natural products and their corresponding salts were synthesized and evaluated for antimalarial activity and cytotoxicity levels. Quaternary carbolinium cations showed much higher potencies than neutral beta-carbolines and a good correlation was observed between pi-delocalized lipophilic cationic structure and antimalarial efficacy.

Animals↗

PubMed2004

Genetic analysis of mefloquine-resistant mechanism of Plasmodium falciparum.

We studied DNA sequence polymorphism, expression level of pfmdr1 gene and sensitivity of major antimalarial drugs in both mefloquine sensitive and resistant strains to elucidate mechanism of mefloquine resistance. Mefloquine-resistant 523a R/24 strain exhibited decreased susceptibility to mefloquine, artemisinin and halofantrine whereas increased susceptibility to chloroquine. We found a novel point mutation in pfmdr1 gene of 523a R/24 strain. Moreover, overexpression of mRNA of pfmdr1 has been observed in this strain. In addition, functional analysis by pfmdr1 antisense revealed correlation of mefloquine sensitivity with expression level of pfmdr1. We suggest that gene mutation and overexpression of pfmdr1 may be associated with mechanism of mefloquine resistance.

Alleles↗

PubMed2004

Antimalarial activity of lavandulyl flavanones isolated from the roots of Sophora flavescens.

Four lavandulyl flavanones, (2S)-2'-methoxykurarinone (1), sophoraflavanone G (2), leachianone A (3), and (-)-kurarinone (4), which are isolated from the roots of Sophora flavescens have been tested for in vitro antimalarial activity against Plasmodium falciparum. Compounds 1-3 showed moderate antimalarial activities with EC(50) values of 2.4 x 10(-6), 2.6 x 10(-6), and 2.1 x 10(-6) M, respectively. These compounds did not show selective toxicity against P. falciparum in the toxicity test on mouse mammalian tumor cells, however, it is suggested that the position of methoxyl groups in flavanone skeleton plays an important role on antimalarial activity.

Animals↗

PubMed2003

Synthesis of 2-fluoronoraristeromycin and its inhibitory activity against Plasmodium falciparum S-adenosyl-L-homocysteine hydrolase.

Palladium-coupling reaction of (1S, 4R)-cis-4-acetoxy-2-cyclopenten-1-ol with sodium salt of 2-fluoroadenine resulted in the formation of (1S,4R)-4-(6-amino-2-fluoro-9H-purin-9-yl)cyclopent-2-en-1-ol. Subsequent oxidation was carried out with osmium tetraoxide (OsO(4)) in the presence of 4-methylmorpholine N-oxide (NMO) to give 2-fluoronoraristeromycin, possessing significant inhibitory activity against recombinant Plasmodium falciparum SAH hydrolase.

Adenosine↗

PubMed2003

Metabolites of febrifugine and its synthetic analogue by mouse liver S9 and their antimalarial activity against Plasmodium malaria parasite.

Quinazolinone type alkaloids, febrifugine (1) and isofebrifugine (2), isolated from Dichroa febrifuga roots, show powerful antimalarial activity against Plasmodium falciparum. Unfortunately, their emetic effect and other undesirable side effects have precluded their clinical use for malaria. Because of their antimalarial potency, analogues were searched for, with the goal of preserving the strong antimalarial activity, while dramatically reducing side effects. We expected that compounds useful in drug development would exist in metabolites derived from 1 and Df-1 (3), the condensation product of 1 with acetone, by mouse liver S9. Feb-A and -B (4 and 5) were isolated as the major metabolites of 1. In addition to 4 and 5, feb-C and -D (6 and 7) were also purified from the metabolic mixture of 3. Compounds 4 and 5 were compounds oxidized at C-6 and C-2 of the quinazolinone ring of 1, respectively. Compounds 6 and 7, derived from 3, also bear febrifugine type structures in which the 4' '- and 6' '-positions of the piperidine ring of 1 were oxidized. In vitro antimalarial and cytotoxic tests using synthetically obtained racemic 4-6 and enantiomerically pure 7 demonstrated that 4 and 6 had antimalarial activity against P. falciparum, of similar potency to that of 1, with high selectivity. The antimalarial activity of 5 and 7, however, was dramatically decreased in the test. The in vitro antimalarial activity of analogues 22 and 43, which are stereoisomers of 4 and 6, was also evaluated, showing that 22 is active. The results suggest that basicity of both the 1- and the 1' '-nitrogen atoms of 1 is crucial in conferring powerful antimalarial activity. Racemic 4 and 6 exhibited powerful in vivo antimalarial activity against mouse malaria P. berghei, and especially, no serious side effects were observed with 4. Thus, the metabolite 4 appears to be a promising lead compound for the development of new types of antimalarial drugs.

Administration, Oral↗

PubMed2003

Synthesis of antimalarial yingzhaosu A analogues by the peroxidation of dienes with Co(II)/O2/Et3SiH.

Co(II)-catalyzed peroxidation of dienes including (S)-limonene in the presence of molecular oxygen and triethylsilane provided in each case the corresponding 2,3-dioxabicyclo[3.3.1]nonane derivatives via the intramolecular cyclization of the unsaturated peroxy radical intermediates. The product composition was remarkably influenced by the structure of the dienes, the nature of the solvents, and the concentration of the substrates and the catalyst. Some of the yingzhaosu A analogues obtained in this study showed notable antimalarial activities in vitro.

Alkadienes↗

PubMed2003

Antimalarial activity of novel 1,2,5,6-tetraoxacycloalkanes and 1,2,5-trioxacycloalkanes.

Photooxygenation of 2-phenylnorbornene 1 in the presence of 30% aqueous hydrogen peroxide afforded 1,2-bishydroperoxide 3, which could be cycloalkylated on treatment with silver oxide and a 1,omega-diiodoalkane to provide the tricyclic peroxides 12. Trimethylsilylation of 3 followed by TMSOTf-catalyzed cyclocondensation with carbonyl compounds led to the formation of the tricyclic peroxides 14 containing a 1,2,4,5-tetroxepane structure. Photooxygenation of 1 in the presence of either unsaturated hydroperoxides or unsaturated alcohols followed by bis(collidine)iodine hexafluorophosphate promoted cyclization gave the corresponding cyclic peroxides 15-17. Several of these cyclic peroxides showed substantial antimalarial activity particularly in vitro.

Animals↗