• 약학회지
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• 제49권5호
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• pp.428-436
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• 2005

DNA topoisomerase I(TOP1) helps the control of DNA replication, transcription and recombination by assist­ing breaking and rejoining of DNA double strand. Camptothecin (CPT) and its derivative, topotecan, are known to inhibit TOP1 by intercalating into TOP1-DNA complex. Recently various non-CPT intercalators are synthesized for a new class of TOP1 inhibitors. In this study, six compounds isolated from Poria cocos were investigated for their interaction with TOP1­DNA complex using the flexible docking program, FlexiDock. The binding modes were analyzed and compared with the TOP1 inhibition activities. The compounds that showed potent activity were intercalated between the + 1/-1 base pairs of DNA, located near the active site phosphotyrosine723 and formed hydrogen bonds with active site residues. On the other hand, compounds with no activity were not docked at all. The binding modes were well correlated with the inhibition activity, suggesting the possibility that potent inhibitors can be designed from the information presented by the docking study.

• 한국미생물·생명공학회지
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• 제24권1호
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• pp.101-104
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• 1996

During the screening of inhibitor of DNA topoisomerase I from microbial secondary metabolites, Streptomyces melanosporofaciens 7489 which was capable of producing high level of inhibitor was selected from soil. The active compound (7489-1) was purified from the culture broth by solvent extraction, silica gel column chromatography and HPLC. The inhibitor was identified as dibutyl phthalate by spectroscopic methods of UV, $^{1}H$-NMR, $^{13}C$-NMR, DEPT and EI-MS. 7489-1 showed a strong inhibitory activity against topoisomerase I with 10 ${\mu}$M of $IC_{50}$ value.

• 생명과학회지
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• 제10권6호
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• pp.621-629
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• 2000

Camptothecin (CPT) is an antitumor alkaloid that has been isolated from the Chinese tree, Camptotheca acuminata. The cytotoxicity of CPT has been correlated to its inhibition of DNA topoisomerase (Topo) I by stabilizing drug-enzyme-DNA “cleavable complex" resulting in DNA single-strand breaks and DNA-protein crosslinks. This studies were designed to elucidate whether CPT regulates Topo I mediated by CPT in DNAs containing c-myc protooncogene. We have conducted experiments on Topo I purification, pUC-MYC I cloning and Topo I assay using electrophoresis, quantitative RT-PCR and Northern blotting techniques. CPT ingibited the relaxation activity of Topo I in pUC19 DNA at various concentrations (1-1000 $\mu$M), while it enhanced the cleavage of Topo I in the pUC-MYC I by forming a cleavable complex at relatively high concentrations (100-1000 $\mu$M). In HL-60 cells treated with CPT, the expression of c-myc gene was decreased over that in the control group with no changes in the expression of Topo I mRNA. Our results suggest that Topo I is the target of CPT cytotoxicity but it does not affect Topo I extression, and the suppression of c-myc mRNA expression by CPT is due to c-myc damage resulted from formation of a cleavable complex with CPT. CPT.

• 한국수산과학회지
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• 제47권3호
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• pp.247-254
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• 2014

To investigate the acquisition of quinolone resistance, we examined mutations in the quinolone resistance-determining region (QRDR) of type II topoisomerase genes in ciprofloxacin (CIP)-resistant clinical isolates and in vitro mutants of Streptococcus parauberis. The CIP-resistant clinical isolates had one base change responsible for a Ser-79${\rightarrow}$Thr in the QRDR of parC. However, the CIP-resistant in vitro mutants had an altered QRDR of parC (Ser-79${\rightarrow}$Ile) that differed from that of the isolates. None of the CIP-resistant S. parauberis clinical isolates or in vitro mutants exhibited amino acid changes in gyrA or gyrB. However, even though involvement in the increased resistance was not clear, an Arg-449${\rightarrow}$Ser mutation outside of the QRDR of parE was detected in CIP-resistant mutant 2P1. These results suggest that the topoisomerase IV gene, parC (and possibly parE, as well), is the primary ciprofloxacin target in S. parauberis. Additionally we established a high-resolution melting (HRM) assay capable of detecting the dominant mutation in four type II topoisomerase genes conferring ciprofloxacin resistance. These rapid and reliable assays may provide a convenient method of surveillance for genetic mutations conferring antibiotic resistance.

• Tuberculosis and Respiratory Diseases
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• 제42권3호
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• pp.302-313
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• 1995

연구배경: 종양괴사인자(Tumor necrosis factor; TNF)는 다양한 생물학적인 작용을 가지며 종양 세포에 대한 세포 독성은 그 대표적인 기능중의 하나이다. TNF-$\alpha$는 생체외에서(in vitro) 몇몇 종양 세포주에 대하여 항암제, 특히 topoisomerase II targeted chemotherapeutic agent의 세포 독성 효과를 상승적으로 증가시키는 것이 알려져 있다. 최근 암세포에 대한 cytokine 유전자 요법에서 TNF는 중요한 대상으로 여겨지고 있으며, 유전자 이입에 의해 암조직이 TNF를 생성하게 될 경우 암 증식 억제 효과가 있음이 보고되고 있다. 연구자는 암세포에 TNF-$\alpha$ 유전자를 이입하여 자신이 TNF-$\alpha$를 생성하도록 형질을 변환시킨 암세포는 topoisomerase II 억제 항암제에 대한 김수성에 변화가 있을 것이라는 가설을 수립하였고 이를 검증하고자 본 연구를 수행하였다. 본 연구에서는 생체외로(in vitro) TNF-$\alpha$ 유전자를 이입하여 TNF-$\alpha$를 생성하는 암세포주에서 topoisomerase II targeted drug에 대한 항암제 감수성 효과가 모세포주에 비하여 증대될 수 있는지를 알아 보고자하였다. 방법: TNF-$\alpha$에 감수성을 보이는 것으로 알려진 인체 중피종 세포주인 NCI-H2058 세포주 및 생쥐의 섬유육종 세포주인 WEHI164 세포주와 인체 비소세포 폐암 세포주인 A549 세포주를 배양하여, 먼저 임상에서 흔히 폐암의 항암 화학 요법 치료에 널리 쓰이는 대표적인 topoisomerase II targeted chemotherapeutic drug인 etoposide(VP-16)와 doxorubicin(adriamycin)을 가하였을 때 관찰된 세포 독성을 MTT assay로 측정하고, 각 모세포주(parenta1 cell line)에 TNF-$\alpha$의 유전자를 이입시켜서 형절 변환한 세포주(transformed cell line)에 대하여 각각 동일한 항암제를 가하였을 때 관찰된 세포 독성의 정도를 같은 방법으로 측정하여, 그 결과를 비교 분석하였다. 또한 모세포주에 외부에서 TNF를 가하여 전처치한 후 동일한 항암제를 가하였을 때의 세포독성을 관찰하여 비교 분석하였다. 결과: H2058 세포주에서는 TNF-$\alpha$ 유전자를 이입한 세포주 topoisomerase II targeted drug을 가하였을 때, 항암제 감수성이 모세포주에 같은 항암제를 가하였을 때에 비하여 의미있게 증가함을 관찰할 수 있었으나(p<0.05), WEHI 세포주와 A549 세포주에 있어서는 TNF-$\alpha$ 유전자를 이입한 세포주에서 모세포주에 비하여 항암제 감수성이 증가하지는 않았다. 결론: TNF-$\alpha$ 유전자의 이입이 topoisomerase II targeted chemotherapeutic drug에 대한 항암제 감수성을 증가시키는 효과는 세포주에 따라 다양한 결과를 보이는 것을 알 수 있었으며, 적어도 선택된 특정 종류의 호흡기계 암세포에 있어서는 TNF-$\alpha$ 유전자의 이입으로 항암제 감수성(chemosensitivity)을 증가시킬 수 있을 것으로 사료된다.

• Archives of Pharmacal Research
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• 제21권6호
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• pp.729-733
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• 1998

The crude extract of Streptomyces sp. strain KM86-9B, isolated from a marine sponge, displayed significant inhibition on topoisomerase I activity. Investigation of the ca usative components by bioactivity-directed fractionation resulted in the isolation of a series of iso- and anteiso-fatty acids.

• BMB Reports
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• 제31권3호
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• pp.245-248
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• 1998

Human epidermoid carcinoma A431 cells have an extraordinarily large number of epidermal growth factor (EGF) receptors, and their growth is inhibited by EGF, which results in growth arrest at the Gl phase. In order to investigate the EGF-mediated inhibition mechanism, the expression level of DNA topoisomerase (topo) II was analyzed after EGF treatment. As a result, it was shown that EGF treatment lowered the amount of 170 kDa topo II (topo $II{\alpha}$) but not 180 kDa (topo $II{\beta}$). However, the A431 cell variant resistant to EGF was not sensitive to EGF treatment. These results suggest that EGF-induced growth arrest of A431 cells may be closely related to the depletion of topo $II{\alpha}$.

• BMB Reports
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• 제29권1호
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• pp.27-31
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• 1996

Using topoisomerase II (topo II) isozyme-specific antibodies, we investigated the phosphorylation of topo $II{\alpha}$ in mitotic HeLa cells. Topo $II{\alpha}$ was specifically modified in the mitotic cells, resulting in slow migration on SDS-polyacrylamide gel electrophoresis. To characterize the nature of this modification, we treated the nuclear extracts prepared from the mitotic cells with alkaline phosphatase. After the treatment with alkaline phosphatase, the slowly migrated band disappeared and instead a normal (170 kDa) topo $II{\alpha}$ band appeared. These results indicate that human topo $II{\alpha}$ is modified at a specific site(s) in M phase by phosphorylation, supporting the possibility that M phase-specific phosphorylation of topo II is critical for mitotic chromosome condensation and segregation.

• Biomolecules & Therapeutics
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• 제24권5호
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• pp.453-468
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• 2016

There is a conserved ATPase domain in topoisomerase II (topo II) and heat shock protein 90 (Hsp90) which belong to the GHKL (gyrase, Hsp90, histidine kinase, and MutL) family. The inhibitors that target each of topo II and Hsp90 are intensively studied as anti-cancer drugs since they play very important roles in cell proliferation and survival. Therefore the development of dual targeting anti-cancer drugs for topo II and Hsp90 is suggested to be a promising area. The topo II and Hsp90 inhibitors, known to bind to their ATP binding site, were searched. All the inhibitors investigated were docked to both topo II and Hsp90. Four candidate compounds as possible dual inhibitors were selected by analyzing the molecular docking study. The pharmacophore model of dual inhibitors for topo II and Hsp90 were generated and the design of novel dual inhibitor was proposed.

• Natural Product Sciences
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• 제7권2호
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• pp.60-62
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• 2001

Ulmus davidiana, Formitella fraxinea, and Aloe vera extracts were detected to have inhibitory effects against topoisomerase I at treatment of $5{\mu}g$. Ulmus davidiana and Aloe vera extracts were found to show inhibitory effect similar to camptothecin, Formitella fraxinea extract was found to have weak activity. We also found the potential use of those extracts as a radiation sensitizer. Radiosensitizing effect at combination treatment was increased more than 2 times at single treatment of radiation, Ulmus davidiana or Formitella fraxinea extracts. Ulmus davidiana and Formitella fraxinea extracts were found to have significant radiosensitizing effect on test tumor cell line. But, Aloe vera extract was not detected to have activity as a radiosensitizer. Ulmus davidiana and Formitella fraxinea extracts are potent radiosensitizers on tumor cell lines and should be considered for further study of active compounds.