NK314, a topoisomerase II inhibitor that specifically targets the alpha isoform.

Topoisomerase II (Top2) is a ubiquitous nuclear enzyme that relieves torsional stress in chromosomal DNA during various cellular processes. Agents that target Top2, involving etoposide, doxorubicin, and mitoxantrone, are among the most effective anticancer drugs used in the clinic. Mammalian cells possess two genetically distinct Top2 isoforms, both of which are the target of these agents. Top2alpha is essential for cell proliferation and is highly expressed in vigorously growing cells, whereas Top2beta is nonessential for growth and has recently been implicated in treatment-associated secondary malignancies, highlighting the validity of a Top2alpha-specific drug for future cancer treatment; however, no such agent has been hitherto reported. Here we show that NK314, a novel synthetic benzo[c]phenanthridine alkaloid, targets Top2alpha and not Top2beta in vivo. Unlike other Top2 inhibitors, NK314 induces Top2-DNA complexes and double-strand breaks (DSBs) in an alpha isoform-specific manner. Heterozygous disruption of the human TOP2alpha gene confers increased NK314 resistance, whereas TOP2beta homozygous knock-out cells display increased NK314 sensitivity, indicating that the alpha isoform is the cellular target. We further show that the absence of Top2beta does not alleviate NK314 hypersensitivity of cells deficient in non-homologous end-joining, a critical pathway for repairing Top2-mediated DSBs. Our results indicate that NK314 acts as a Top2alpha-specific poison in mammalian cells, with excellent potential as an efficacious and safe chemotherapeutic agent. We also suggest that a series of human knock-out cell lines are useful in assessing DNA damage and repair induced by potential topoisomerase-targeting agents.

OSW-1 analogues: modification of the carbohydrate moiety.

4 OSW-1 analogues featuring modified carbohydrate moieties were prepared. The purpose of these modifications was to assess the importance of certain chemical functions with respect to biological activity. The synthesis and biological activity of the target molecules are shown.

Cytotoxicity of lissoclibadins and lissoclinotoxins, isolated from a tropical ascidian Lissoclinum cf. badium, against human solid-tumor-derived cell lines.

The in vitro growth inhibitory activity of lissoclibadins and lissoclinotoxins isolated from the tropical ascidian Lissoclinum cf. badium against nine human cancer cell lines was examined to evaluate their potential anticancer efficacy. Lissoclibadins 1 (1) and 2 (2), and lissoclinotoxin F (4) showed the strongest activity of the six compounds tested, which were more potent than the anticancer drug cisplatin. Compound 1 has a trimeric structure, and compounds 2 and 4 are structural isomers possessing dimeric structures connected by disulfide and sulfide bonds of trans- and cis-orientations, respectively. Lissoclibadin 3 (3), a dimeric compound connected by two sulfide bonds, and two monomeric compounds (5, 6) were less active than 1, 2, and 4. Lissoclibadin 2 (2) was the most interesting compound possessing potent inhibitory activity against colon (DLD-1 and HCT116), breast (MDA-MB-231), renal (ACHN), and non-small-cell lung (NCI-H460) cancer cell lines and showing no toxicity following a 50 mg/kg single treatment to mice, and preferable stability in rat plasma.

Impact of chymase inhibitor on cardiac function and survival after myocardial infarction.

OBJECTIVES: Recent studies have demonstrated that hamsters, like humans, possess both angiotensin converting enzyme (ACE)- and chymase-dependent angiotensin (Ang) II-forming pathways in cardiovascular tissues. We recently found that, after myocardial infarction (MI) in hamsters, cardiac chymase was significantly activated. In order to determine whether suppression of cardiac chymase activity could provide prognostic benefit after MI, we examined the effects of NK3201, a novel, orally active and specific chymase inhibitor, on cardiac function and survival during the acute phase of MI in hamsters. METHODS: Two hundred and ten male Syrian hamsters were used in the present study. The left coronary artery of each hamster was ligated to induce MI. NK3201 at a dose of 30 mg/kg per day was administered orally by gastric gavage, starting either 3 days before or 1 day after MI. RESULTS: ACE and chymase activities were significantly increased in the infarcted left ventricle 3 days after MI. NK3201 treatment starting 3 days before MI significantly inhibited the increase in cardiac chymase activity, while it did not affect ACE activity either in plasma or in heart 3 days after MI. A significant improvement in cardiac function was observed 3 and 14 days after MI in the group receiving NK3201. Compared with vehicle treatment, NK3201 treatment initiated either 3 days before or 1 day after MI significantly reduced the mortality rate during the 14 days of observation following MI. CONCLUSIONS: These findings indicate that cardiac chymase plays an important role after MI and this finding may provide a novel therapeutic target in post-MI treatment.

A novel chymase inhibitor, 2-(5-formylamino-6-oxo-2-phenyl-1,6-dihydropyrimidine-1-yl)-N-[[,4-dioxo-1-phenyl-7-(2-pyridyloxy)]2-heptyl]acetamide (NK3201), suppressed intimal hyperplasia after balloon injury.

In this study, we investigated whether an orally active chymase inhibitor, 2-(5-formylamino-6-oxo-2-phenyl-1,6-dihydropyrimidine-1-yl)-N-[[3,4-dioxo-1-phenyl-7-(2-pyridyloxy)]-2-heptyl]acetamide (NK3201), prevents intimal hyperplasia in carotid arteries injured by a balloon catheter in dog. Each dog was administered NK3201 (1 mg/kg per day, p.o.) or placebo beginning 5 days before balloon injury and continuing through the experiments. Four weeks after balloon injury, NK3201 did not affect the plasma renin and angiotensin-converting enzyme activities. The chymase activity was significantly increased in the injured arteries, whereas the angiotensin-converting enzyme activity was not. NK3201 significantly reduced the chymase activity in the injured arteries. The intimal area in the placebo- and NK3201-treated group and was 0.46 +/- 0.06 and 0.24 +/- 0.04 mm2, respectively, and this difference was significant. In this study, we demonstrated for the first time that a chymase inhibitor prevented the development of intimal hyperplasia in the balloon-injured arteries.

Development of the chymase inhibitor as an anti-tissue-remodeling drug: myocardial infarction and some other possibilities.

Chymase leading to tissue remodeling is expected to be a potent pharmaceutical target. Its functions in vivo are still unclear, because of lack of orally available inhibitors. Recently, however, the chymase inhibitor NK3201 (2-(5-formylamino-6-oxo-2-phenyl-1,6-dihydropyrimidin-1-yl)-N-[[3,4-dioxo-1-phenyl-7-(2-pyridyloxy)]-2-heptyl] acetamide) was demonstrated to have oral activity against neointimal hyperplasia in dog models (Takai S. et al., Life Sci 69, 1725 - 1732 (2001)). In this review, by showing the efficacy of NK3201 in some hamster models, chymase functions in vivo are summarized, and the potency of this chymase inhibitor is introduced. In vitro study, NK3201 showed potent chymase specific inhibitory activity, and Dixon plot analysis indicated competitive inhibition. Oral administration of NK3201 into normal rats resulted in rapid spread over every tissue except the brain, and sufficient activity to inhibit tissue chymase was detected even after 24 h. In passive cutaneous anaphylaxis, myocardial infarction and bleomycin-induced pulmonary fibrosis models, orally administered NK3201 showed potent inhibition of inflammatory response, tissue angiotensin II formation, and fibrosis, respectively. These data suggest that chymase has a vital role in tissue remodeling through promotion of the inflammatory response, tissue angiotensin II and tissue fibrosis. Our recent data indicated chymase participation in bladder fibrosis, like interstitial cystitis. Therefore, the orally active chymase inhibitor NK3201 may have protective effects on tissue remodeling in several diseases.