• 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.

• Journal of Microbiology and Biotechnology
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• 제6권5호
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• pp.366-367
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• 1996

Dibutyl phthalate induced topoisomerase Ⅰ mediated DNA relaxation comparable to that of camptothecin, and topoisomerase Ⅱ mediated DNA relaxation equipotent to that of 4'-(9-acridinylamino) methanesulfon-m-anisidide (m-AMSA). The relaxation activities of dibutyl phthalate were dose-de-pendent and nearly as potent as those of camptothecin and m-AMSA.

• 한국식품과학회지
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• 제29권5호
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• pp.1057-1062
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• 1997

26속 32종의 버섯의 topoisomerase II 작용 억제여부를 검색한 결과 말불버섯이 topoisomerase II 작용을 억제하며 그 유효 성분이 핵산분획물에 존재함을 확인하였다. 말불버섯의 핵산분획물은 linear DNA와 open circular DNA를 생성시켰으며 농도와 반응시간에 의존적인 반응 양상을 나타냈다. 또한 말불버섯의 핵산분획물은 topoisomerase I의 작용도 억제하였다. 그러나 배양한 말불버섯의 균사체는 topoisomerase 작용에 아무런 영향을 미치지 않았다.

• 약학회지
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• 제40권6호
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• pp.697-704
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• 1996

Quinolone derivatives, SJ5b (ethyl 5,12-dihydro-5-dihydro-5-oxobenzoxazolo[3,2-a]quinoline-6-carboxylate) and SQ7b (3-fluoro-2-(4-methylpiperazin-1-yl)-5.12-dihydro-5-oxobenzoxa zolo[3,2-a]quinoloine carboxylic acid) showed in vitro cytotoxicities against various tumor cell lines. SJ5b and SQ7b completely inhibited the DNA relaxation activities of human placental topoisomerase II at the concentration of 15.63 and 1.95 ${\mu}$g/ml, respectively. However, unlike etoposide which stabilize the topoisomerase II-DNA complex, SQ7b did not cause topoisomerase II-mediated DNA cleavage and SJ5b weakly stabilized the topoisomerase II-DNA cleavable complex. Through both experiments. DNA relaxation assay by the increment of topoisomerase II concentration and DNA unwinding assay, it was shown that SJ5b and SQ7b did not interact with topoisomerase II itself but bound to DNA. Therefore, it was concluded that DNA binding of SJ5b and SQ7b caused the inhibition of topoisomerase II related to DNA relaxation but no or very weak stabilization of topoisomerase II-DNA cleavable complex. In addition, SJ5b and SQ7b prevented whole cell nucleic acid syntheses in HL60 cells.

• 생약학회지
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• 제30권1호
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• pp.1-6
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• 1999

To evaluate cytotoxic effect and topoisomerase I inhibition activity of Caesalpinia sappan L., both water and methanol extracts were examined using in vitro assay. The cytotoxic effect of Caesalpinia sappan L. examined using MTT and SRB assay and $IC_{50}$ values were measured against U937, HL60, HepG2, SNU-1, SNU-16 cancer cell lines. Among them the representative cytotoxic results are shown as follows; water extract (U937=13.39 ${\mu}g/ml$, HL60=8.65 ${\mu}g/ml$, HepG2=38.48 ${\mu}g/ml$, SNU-1=7.72 ${\mu}g/ml$, SNU-16=25.49 ${\mu}g/ml$), methanol extract (U937=13.35 ${\mu}g/ml$, HL60=9.43 ${\mu}g/ml$, HepG2=25.67 ${\mu}g/ml$, SNU-1=8.37 ${\mu}g/ml$, SNU-16=28.64 ${\mu}g/ml$). The inhibitory concentration of DNA topoisomerase I activity against water extract was 100 ${\mu}g/ml$ and the inhibitory concentration of DNA topoisomerase I against methanol extract was 400 ${\mu}g/ml$.

• BMB Reports
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• 제31권3호
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• pp.249-253
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• 1998

The developmental regulation of Caenorhabditis elegans DNA topoisomerase I expression was examined using synchronized Caenorhabditis elegans cultures. Variations of the relative mRNA and protein levels of the enzyme during their development were measured by Northern and Western analyses, respectively. The mRNA level was the highest at the embryonic stage, decreasing rapidly to the one tenth level at the L1 stage, and then increasing by a few fold at the L4 and young adult stages. The protein level was the highest at the L1 stage, with gradual decreasing at the following stages until it showed a slight increase at the young adult stage. Based on our results of the expressional regulation, the possible roles of DNA topoisomerase I in the development of C. elegans are discussed.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1769-1772
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• 2012

• Bulletin of the Korean Chemical Society
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• 제26권11호
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• pp.1829-1832
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• 2005

• Bulletin of the Korean Chemical Society
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• 제33권9호
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• pp.3103-3106
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• 2012

• Bulletin of the Korean Chemical Society
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• 제31권6호
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• pp.1747-1750
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• 2010