• Asian Pacific Journal of Cancer Prevention
• /
• v.17 no.11
• /
• pp.4853-4856
• /
• 2016

Objective: Gimatecan is a new camptothecin (CPT) analogue that inhibits tumor growth by targeting DNA topoisomerase I (TOP I) and introducing strong and persistent DNA cleavage. Anti-tumor activity has been demonstrated with a wide range of solid tumors in previous preclinical and clinical studies. Here, we investigated for the first time the effects of gimatecan on the proliferation of hepatocellular carcinoma (HCC) cells both in vitro and in vivo. Methods: Anticancer efficacy of gimatecan were evaluated in a panel of HCC cell lines and corresponding mouse xenograft models. Inhibition of cell proliferation was measured by CellTiter-Glo cell viability assay. In vivo, gimatecan and control preparations were orally administered every four days, for a total of four times. Tumor volume and body weights of the mice were measured twice weekly. Results: In vitro cytotoxicity evaluation showed that gimatecan inhibited the proliferation of a large panel of HCC cell lines in a dose dependent manner, with IC50 values ranging between 12.1~1085.0 nM. In vivo evaluation in mouse xenograft models showed significant antitumor effects of gimatecan at 0.8mg/kg and 0.4mg/kg as compared to the control group. Conclusion: This study suggested that gimatecan may have the potential to be used as a chemotherapeutic agent for the treatment of HCC.

• Archives of Pharmacal Research
• /
• v.27 no.8
• /
• pp.829-833
• /
• 2004

The bioactivity-guided fractionation of the methylene chloride extract of the sclerotium of Poria cocos led to the isolation of (S)-(＋)-turmerone (1), ergosterol peroxide (2), polyporenic acid C (3), dehydropachymic acid (4), pachymic acid (5), and tumulosic acid (6). Compounds 4-6 exhibited moderate cytotoxicities, with $IC_{50}$ values of 20.5, 29.1, and $10.4{\;}\mu\textrm{m}$, respectively, against a human colon carcinoma cell line. However, 3-6 not only showed inhibitory activities as potent as etoposide used as a positive control on DNA topoisomerase II (36.1, 36.2, 43.9 and 66.7％ inhibition at a concentration of $20{\;}\mu\textrm{m}$, respectively), but also inhibition of DNA topoisomerase I (55.8, 60.7, 43.5, and 83.3％ inhibition at a concentration of $100{\;}\mu\textrm{m}$, respec-tively).

• Environmental Mutagens and Carcinogens
• /
• v.9 no.1
• /
• pp.13-22
• /
• 1989

The effect of novobiocin (NOV), and inhibitor of topoisomerase II, on ethyl methanesulfonate (EMS)-or bleomycin (BLM)-induced DNA repair synthesis was examined during the cell cycle of Chinese hamster ovary (CHO)-K1 cells. Three assays were employed in this study: cell survival, alkaline elution and unscheduled DNA synthesis. EMS was effective at killing CHO cells in G1 phase, wheras BLM preferentially killed cells in G2 and S phases. EMS induced the much more amount of DNA damage in G1 phase, while BLM induced in G2 phase than the other phases. The both of pre- and post-treatment with BOV inhibitied EMS- or BLM-induced DNA repair synthesis in G1 and G2 phases, and pretreatment with NOV inhibited more effectively than the post-treated group. These results suggested that CHO cells exhibited a differential sensitivity to cell lethality and DNA damage in relation to cell cycle according to used chemical agents, and that DNA topoisomerase II participated in an initial stage of DNA repair.

• The Journal of Korean Medicine
• /
• v.22 no.2
• /
• pp.22-30
• /
• 2001

This study was attempted to investigate the anti-tumor and anti-metastatic effects of Sobokchukeotang(SBCT) and Kamisobokchukeotang(KSBCT). Cytotoxicity against various cancer cell lines, anti-adhesion, pulmonary colonization, anti-angiogenesis, and T/C% were evaluated. SBCT and KSBCT exhibited no cytotoxicity against HT-1080, A549, SK-OV-3, B16-F10 and SK-Mel-2 cell lines. In inhibitory effect on DNA topoisomerase I, the $IC_{50S}$ were shown $250-500{\;}\mu\textrm{g}/ml$ of SBCT and $62.5-125{\;}\mu\textrm{g}/ml$ of KSBCT respectively. In the in vivo experiments, SBCT(135.98%) and KSBCT(151.92%) apparently increased the life span of mice bearing sarcoma-180. KSBCT significantly inhibited the adhesion of HT-1080 to complex extracellular matrix in a dose-dependent manner in contrast to SBCT. In pulmonary colonization assay by B16-F10, a number of colonies in the lungs were decreased more significantly in KSBCT group than those in SBCT group. In vitro neovascularization and CAM assay, angiogenesis was more significantly inhibited in KSBCT-treated group than in SBCT- treated group. Above results suggests that KSBCT is more effectively applied to prevention and treatment of cancer than SBCT.

• Proceedings of the Microbiological Society of Korea Conference
• /
• 1991.04a
• /
• pp.82-96
• /
• 1991

To understand the mechanism of illegitimate recombination in mammalian cells, we have examined the recombination role of DNA topoisomerase II (Topo II ). We found that purified calf thymus Topo II mediates recombination between two phage $\lambda$ DNA molecules in an in vitro system. The enzyme mainly produced a linear monomer recombinant DNA that can be packaged in vitro. Novobiocin and anti-calf thymus Topo II antibody inhibit this ATP-dependent recombination. The recombinant molecules contain duplications or deletion, and most crossovers take place between nonhomologous sequences of $\lambda$ DNA, as judged by the sequences of recombination junctions. In order to study the effects of Topo II on illegitimate recombination in mammalian cells, we have developed a new shuttle vector, pNKl, which contains three bacterial genes, amp(APR), galK and neo($Km^R$). Using this system, we have shown that a Topo II inhibitor, VM26, stimulated deletion formation in pNK1 DNA in monkey COS1 cells. Both in vitro and in vivo results suggest that Topo II participates in illegitimate recombination in mammalian cells.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.16 no.3
• /
• pp.472-478
• /
• 2002

The purpose of this study was to investigate the effect of Kamigedang-tang(KGDT) water extract on the antitumor and anti metastatic activity. The results were summarized as follows: KGDT extracts exhibited a significant cytotoxicity against P388, SK-MEL-2, SK-OV-3, and B16-F10 cell lines and showed significant inhibitoty effect on DNA topoisomerase I from calf thymus. The T/C% was 122.9% in KGDT treated group in S-180 bearing ICR mice. Also, KGDT extracts exhibited efficient affect adhesive effect of A549 cell to complex extracellular matrix. In CAM assay, KGDT extracts inhibited angiogenesis at 15㎍/egg concentration insignificantly as compared with control. These results suggested that KGDT extracts might be usefully applied for prevention and treatement of cancer.

• Archives of Pharmacal Research
• /
• v.21 no.5
• /
• pp.595-598
• /
• 1998

The rate of the GSH conjugate formation, the inhibition of DNA topoisomerase-I and the cytotoxic activity against L1210 cells of the naphthoquinones showed the same order; 5,8-dimethoxy-1,4-naphthoquinone (DMNQ)>6-(1-hydroxyethyl)-DMNQ>2-(1-hydroxyethyl)-DMNQ; the steric hindrance of the substituents, particularly 2-substutuent, in reacting with cellular nucleophiles must be the main cause for lowering the bioactivities. Acetylation of 2-(1-hydroxyethyl)-DMNQ producing 2-(acetyloxyethyl)-DMNQ potentiated the bioactivities; 2-(-hydroxyethyl)-DMNQ did not react with GSH and the enzyme, and showed $ED_{50}$ of 0.146 mg/ml for the cytotoxcity. Furthermore, the acetylation 2-(1-hydroxyethyl)-DMNQ(T/C, 119%) enhanced the T/C values for the mice bearing S-180 tumor {T/C of 2-(1-acetyloxyethyl)-DMNQ, 276%]. It was assumed that the difference in bioactivities ensued by acetylation was based on the mechanism of the so-called bioreductive alkylation.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.10
• /
• pp.1559-1563
• /
• 2004

The topoisomerase II poisoning effect of certain protoberberine alkaloids is associated with anti-cancer activity. Structure-activity relationships of protoberberine analogues substituted on the ring protons reveal that substitution at the C19 position is an important determinant of biological activity. In this study, the effects of substituent modification at the C19 position on the interaction of protoberberines with DNA are determined using UV and NMR spectroscopy. The line broadening effect on aliphatic resonances, chemical shift changes of the imino protons of HP14 upon berberine and berberrubine binding to HP14, and the rate of the exchange process between protoberberine analogs bound indicate that berberrubine binds HP14 more specifically than berberine. In addition, the free HP14 is altered by the substituent at the 19-position. UV spectra of berberrubine have shown a hypochromic effect together with a slight red shift, which are usually regarded as characteristics of DNA intercalation. These results are consistent with our previous report that the berberrubine is partially intercalated with HP14 with molar ratio 1 : 1, whereas a non-specific interaction is predominant between the berberine and HP14.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.5
• /
• pp.579-582
• /
• 2003

Norfloxacin, that inhibits the action of topoisomerase Ⅱ, binds to wide variety of DNA. The binding mode of this drug to double- and super-coiled DNA (ds- and scDNA) is compared in this study by various spectroscopic methods, including absorption, fluorescence, and circular dichroism(CD) spectroscopy. Hypochromism in the absorption band, negative and positive induced CD bands (respectively in 240-260 nm and 270-300 nm region) are apparent for the norfloxacin that bound to both the dsDNA and scDNA. A decrease in fluorescence is also noticed in the presence of both DNAs. Since the spectroscopic characteristics are the same for both complexes, it is imperative that the binding mode of the norfloxacin is similar in ds- and scDNA. In the presence of $Mg^{2+}$, which is a cofactor in the topoisomerase Ⅱ action, the fluorescence intensity of the scDNA-norfloxacin complex increased and the resulting fluorescence intensity and shape was identical to that in the absence of scDNA. Therefore, the addition of an excess amount of $Mg^{2+}$ may result in the extrusion of norfloxacin from scDNA.

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