• YAKHAK HOEJI
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• v.53 no.4
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• pp.228-234
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• 2009

Topoisomerase I (Topo I) participates in the DNA replication, transcription, and repair. Binding of Topo I inhibitor to the Topo I-DNA cleavage complex forms stabilized ternary complex which blocks DNA religation and ultimately causes cell death. Camptothecin (CPT) and its derivatives have been among the most effective anticancer drugs by inhibition of topo I. However, efforts to synthesize non-CPT drugs have been actively going on because the CPT derivatives have several limitations such as poor solubility, short half-life, and side effects. As an indenoisoquinoline, NSC314622 is not as potent as CPT, but its chemical stability and slower reversibility of the cleavage complex made it a good lead compound. Recently, a series of indenoisoquinoline analogues were synthesized with substituted dimethoxy or methylenedioxy on the aromatic ring and alkylamino on the lactam nitrogen. Some of them showed quite good Topo I inhibitory activity. Using the computer docking program, Surflex-Dock, indenoisoquinoline analogues were docked into the human Topo I-DNA cleavable complex. The docking results showed that the compounds with activity better than NSC314622 intercalated between the -1 and +1 base pairs at the cleavage site, but those with little or no activities did not appear to intercalate. These results could be useful to design new Topo I inhibitors improved than CPT.

• Archives of Pharmacal Research
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• v.23 no.4
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• pp.338-343
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• 2000

The effects of methanol extract of Rubus crategifolius roots and its solvent fractions were investigated on the proliferation of MCF-7 human breast carcinoma cells. The methanol extract inhibited the proliferation of MCF-7 cells in a concentration dependent manner. Moreover, their methanol soluble (W-M) fraction had the greatest inhibitory effect on the growth of MCF-7 cells. To evaluate whether the W-M fraction affects on the cell cycle of MCF-7 cells, cells treated with this fraction were analyzed with flow cytometry. The W-M fraction increased $G_0$/$G_1$phase after 24 h-treatment and induced apoptosis after 48 h-treatment. The hallmark of apoptosis, DNA fragmentation, also appeared by W-M fraction after 48 h-treatment. Furthermore, the methanol extract and its W-M fraction inhibited the activity of the topoisomerase 1 enzyme in the relaxation assay, From these results, their W-M fraction as well as methanol extract of R. crategifolius roots are necessary for further studies as a potent inhibitor of the growth of cancer cells.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.3
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• pp.177-185
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• 2010

Introduction: Epidermal growth factor receptor (EGFR) is expressed in human epithelial tumors including salivary cancers, and known to be correlated with tumor progression and poor clinical courses in some epithelial tumors. In this study, we determined the therapeutic effect of the anti-EGFR monoclonal antibody Erbitux (C225, cetuximab) in combination with the DNA topoisomerase I inhibitor irinotecan (CPT-11) on human salivary adenoid cystic carcinoma (SACC) cells growing in nude mice. Materials and Methods: At first, immunocytochemical analysis for the expression of EGFR and phosphorylated EGFR (pEGFR) on a human salivary ACC cell line (ACC3). To determine the in vivo effects of Erbitux and CPT-11, nude mice with orthotopic parotid tumors were randomized to receive intraperitoneal Erbitux (1 mg) two times per week, intraperitoneal Irinotecan (50 mg/kg) once per week, Erbitux plus CPT-11, or placebo. (control) Tumor volume and weight were measured. And mechanisms of in vivo activity of Erbitux and/or CPT-11 were determined by immunohistochemical/ immunofluorescent analyses. Results: Immunocytochemical staining of ACC3 demonstrated that EGFR was expressed and phosphorylated. CPT-11 inhibited ACC tumor growth in nude mice. Tumors of mice treated with CPT-11 and CPT-11 plus Erbitux exhibited increased tumor cell apoptosis and decreased microvessel density, which correlated with a decrease in the tumor volume in nude mice. But, CPT-11 seems not to be synergistic with Erbitux in our ACC3 model system. Conclusion: These results suggest that anti-EGFR monoclonal antibody and the DNA topoisomerase I inhibitor will be effective in the treatment of recurred or metastatic lesions of salivary ACC.

• YAKHAK HOEJI
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• v.53 no.4
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• pp.222-227
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• 2009

Human topoisomerase I (Topo I) plays a pivotal role in cell replication, transcription and repair and, therefore, is an important anti-cancer target. 20S-camptothecin (CPT) is a representative Topo I inhibitor. Compounds belonging to CPT family inhibit the religation step of Topo I-DNA by binding to the DNA cleavage site. Computational docking studies with Surflex-Dock were carried out to investigate the binding modes between Topo I-DNA binary complex structure and the ligand such as 20S-CPT and 9,10-substituted 20S-CPT analogues. The docking results demonstrated that most of the compounds with $IC_{50}$ value under $0.5{\mu}M$ intercalated exactly between the -1 and +1 DNA bases, deeply toward the cleavage site. The complex was stabilized by hydrogen-bonding and hydrophobic interactions with both the enzyme and the DNA. The compounds with $IC_{50}$ value above $0.5{\mu}M$ were poorly docked and did not intercalate. In addition, the docking results confirmed the overall correlation between the $IC_{50}$ values and docking scores, indicating the possible use of the modeling for the prediction of biological activity and design of potential inhibitors.

• Journal of Life Science
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• v.12 no.4
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• pp.469-476
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• 2002

The DNA topoismerase I inhibitor $\beta$-lapachone, the product of a tree from South America, is known to exhibit various biological properties, however the mechanisms of which are poorly understood. In the present report, we investigated the effects of $\beta$-lapachone on the growth of human prostate carcinoma DU-145 cells. Upon treatment with $\beta$-lapachone, a concentration-dependent inhibition of cell viability was observed and cells developed many of the hallmark features of apoptosis, including condensation of chromatin and DNA fragmentation. Flow cytometry analysis confirmed that $\beta$-lapachone increased populations of apoptotic-sub Gl phase. In addition, proteolytic cleavages of poly (ADP-ribose) polymerase (PARP) and $\beta$-catenin protein were observed after treatment of $\beta$-lapachone. These apoptotic effects of $\beta$-lapachone in DU-145 cells were associated with marked induction of Bax protein, however the levels of Bcl-2 expression were decreased in a dose-dependent manner.

• Animal cells and systems
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• v.15 no.1
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• pp.9-17
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• 2011

Colorectal cancer is the third leading cause of cancer-related death in Western countries. Chemotherapeutic agents with different mechanisms of action have shown an increase in cure rates. In the present study, we investigated the effect of a combination of low concentration of paclitaxel (taxol, 5 nM) and topoisomerase 1 inhibitor camptothecin (CPT) on HCT116 colon cancer cells. Although the viability of cells treated with taxol alone was similar to that of control cells, sequential treatment with taxol and CPT exhibited high cytotoxicity. However, the opposite sequence of treatment did not exert cytotoxic effects on HCT116 cells. This enhanced cytotoxicity of the sequential combination therapy was the result of mitotic arrest, which increased the level of $p21^{Cip1/WAF1}$ through the p38 mitogen-activated protein kinase (MAPK) pathway. Knockdown by $p21^{Cip1/WAF1}$ siRNA or treatment with a p38 inhibitor reduced the viability of cells sequentially exposed to taxol and CPT. Taken together, a low taxol concentration in combination with CPT induced mitotic arrest in HCT116 cells, leading to synergistic cell death through enhanced expression of $p21^{Cip1/WAF1}$ and p38 MAPK pathway. Therefore, taxol could playa role as a sensitizer of CPT in colon cancer cells.

• Bulletin of the Korean Chemical Society
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• v.32 no.1
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• pp.303-306
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• 2011

• Journal of Life Science
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• v.8 no.2
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• pp.158-161
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• 1998

An inhibitor of farnesy-protein transferae is known to be a fgood candidate for antitumor agent that block the oncogenic activity of Ras protein . We recently isolated and characterized dihydrotanshinone I from Salvia miltiorrhiza Bunge (Danshen), an oriental herb, which has an inhibitory activity of toposimerase I to some cancer cell lines. In order to examine the molecular mechanism of dihydrotanshinone I, we studied the farmesy-Protein Transferase activity by dihydrotanshinone I. As a result, we found that result, we found that dihydrotanshinone I showed inhibitory effect on farnesyl-protein transferase with $IC_{50}$ value of 15 ug/ml. This result suggest that dihydrotanshinone I may be an useful anticancer agent with the inhibitory activity of farnesyl-protein transferase.

• Proceedings of the PSK Conference
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• 2001.10a
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• pp.237.2-237.2
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• 2001

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.31 no.1
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• pp.7-12
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• 2005

Purpose: CKD-602, a newly developed water-soluble campthotecin analogue, is a anticancer agent which act as a DNA topoisomerase I inhibitor. CKD-602 is known as more potent and tolerable agent. The main purposes of this study were to measure the cytotoxic effect of CKD-602 on the oral cancer cell lines and to evaluate the apoptotic aspect of dead cells. Materials and Methods: To determine the cytotoxic effect of CKD-602 on the oral cancer cell lines in comparison with various cell lines, such as lung cancer and colon cancer cell lines, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay was performed. And apoptosis was analyzed using fluorescence-activated cell sorting(FACS) system. Results: CKD-602 decreased the viability of malignant cells in a dose dependent manner and in a time dependent manner. CKD-602 showed excellent cytotoxicity to the oral cancer cell lines. Also, apoptotic portion was increased in a dose dependent manner. Conclusion: These findings indicated that CKD-602 induced apoptotic cell death in the various cell lines including oral cancer cell lines. From the results, it was suggested that CKD-602 would be a potential therapeutic agent for the oral cancer. More successive researches on the anticancer effect of CKD-602 should be performed.