• Archives of Pharmacal Research
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• v.29 no.7
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• pp.541-547
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• 2006

Four alkaloids (1-4), three quinolone alkaloids (5-7), and three flavanoid glucosides (8-10) were isolated from the fruits of Evodia officinalis Dode, and their structures were determined from chemical and spectral data. Compounds, 3, 8, 9 and 10 were isolated from this plant for the first time. Of these compounds, 1-3 and 5-7 exhibited moderate cytotoxicities against cultured human colon carcinoma (HT-29), human breast carcinoma (MCF-7), and human hepatoblastoma (HepG-2). Compound 8 showed strong inhibitory effects on DNA topoisomerases I and II (70 and 96% inhibition at a concentration of $20\;{\mu}M$, respectively).

• Archives of Pharmacal Research
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• v.21 no.5
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• pp.581-590
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• 1998

We developed a novel water-soluble camptothecin analobue, CKD602, and evaluated the inhibition of topoisomerase I and the antitumor activities against mammalian tumor cells and human tumor xenografts. CKD602 was a nanomolar inhibitor of the topoisomerase I enzyme in the cleavable complex assay. CKD602 was found to be 3 times and slightly more potent than topotecan and camptothecin as inhibitors of topoisomerase, respecitively. In tumor cell cytotoxicity, CKD602 was more potent than topotecan in 14 out of 26 human cancer cell lines tested, while it was comparable to camptothecin. CKD602 was tested for the in vivo antitumor activity against the human tumor xenograft models. CKD602 was able to imduce regression of established HT-29, WIDR and CX-1 colon tumors, LX-1 lung tumor, MX-1 breast tumor and SKOV-3 ovarian tumor as much as 80, 94, 76, 67, 87% and 88%, respectively, with comparable body weight changes to those of topotecan. Also the therapeutic margin (R/Emax: maximum tolerance dose/$ED-{58}$) of CKD602 was significantly higher than that of topotecan by 4 times. Efficacy was determined at the maximal tolerated dose levels using schedule dependent i.p. administration in mice bearing L1210 leukemia. On a Q4dx4 (every 4 day for 4 doses) schedule, the maximum tolerated dose (MTD) was 25 mg/kg per administration, which caused great weight loss and lethality in <5% tumor bearing mouse. this schedule brought significant increase in life span (ILS), 212%, with 33% of long-term survivals. The ex vivo antitumor activity of CKD602 was compared with that of topotecan and the mean antitumor index (ATI) values recorded for CKD602 were significantly higher than that noted for topotecan. From these results, CKD602 warrants further clinical investigations as a potent inhibitor of topoisomerase I.

• Journal of Life Science
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• v.17 no.9 s.89
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• pp.1204-1210
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• 2007

The topoisomerase II inhibitor etoposide causes an accumulation of DNA double strand breaks within the nuclei of cells. In this study, we investigated the effect of etoposide on the cell growth and apoptosis of human RPE cells. Etoposide evoked a significant inhibition of cell growth, and also induced DNA fragmentation in ARPE-19 cells. In addition, etoposide significantly up-regulated the expression of heme oxygenase-1 (HO-1), which is a stress-responsive protein and is known to play a protective role against the oxidative injury. And, etoposide-induced HO-1 expression was affected by the ROS scavenger N-acetyl cysteine. We also used oligonucleotides interfering with HO-1 mRNA (siRNA) for the inhibition of HO-1 expression. Interestingly, knock-down of the HO-1 gene significantly increased the level of DNA fragmentation in etoposide-treated ARPE-19 cells. In conclusion, these results suggest that up-regulated HO-1 plays as an anti-apoptotic factor in the process of apoptosis of ARPE-19 cells stimulated by etoposide.

• Journal of Life Science
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• v.15 no.3 s.70
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• pp.323-331
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• 2005

The objective of the present study was to investigate the effect of $\beta-lapachone$, a quinone obtained from the bark of the lapacho tree (Tabebuia avellanedae) in South America, on the cell growth of human hepatoma (HepG2) and bladder (T24) carcinoma cells. Exposure of cancer cells to $\beta-lapachone$ resulted in growth inhibition, morphological changes and apoptosis in a concentration-dependent manner, which could be proved by MTT assay and flow cytometry analysis. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analyses revealed that $\beta-lapachone$ did not affect the levels of tumor suppressor p53 and cyclin-dependent kinase (Cdk) inhibitor p21 (WAFl/CIPl) expression. However, the transcriptional factor Sp-l and proliferating cell nuclear antigen (PCNA) protein levels were significantly down-regulated by $\beta-lapachone$ in both cell lines. Moreover, $\beta-lapachone$ treatment caused a dose-dependent inhibition of the expression of telomere regulatory gene products such as human telomere reverse transcriptase (hTERT) and telomerase-associated protein-l (TEP-l). Taken together, these findings suggest that $\beta-lapachone$-induced inhibition of human hepatoma and bladder carcinoma cell proliferation is associated with the induction of apoptotic cell death via modulation of several major growth regulatory gene products, and provide important new insights into the additional mechanisms of the anti-cancer activity of $\beta-lapachone$.

• Journal of Life Science
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• v.16 no.4
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• pp.589-597
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• 2006

Genistein, a natural isoflavonoid phytoestrogen, is a strong inhibitor of protein tyrosine kinase and DNA topoisomerase activities. There are several studies documenting molecular alterations leading to cell cycle arrest and induction of apoptosis by genistein as a chemopreventive agent in a variety of cancer cell lines; however, its mechanism of action and its molecular targets on human bladder carcinoma and leukemic cells remain unclear. In the present study, we have addressed the mechanism of action by which genistein suppressed the proliferation of T24 bladder carcinoma and U937 leukemic cells. Genistein significantly inhibited the cell growth and induced morphological changes, and induced the G2/M arrest of the cell cycle in both T24 and U937 cells with a relatively stronger cytotoxicity in U937. The G2/M arrest in T24 cells was associated with the inhibition of cyclin A, cyclin B1 and Cdc25C protein expression without alteration of tumor suppressor p53 and cyclin-dependent kinase (Cdk) inhibitor p21(WAF1/CIP1). However, the inhibitory effects of genistein on the cell growth of U937 cells were connected with a marked inhibition of cyclin B1 and an induction of Cdk inhibitor p21 proteins by p53-independent manner. These data suggest that genistein may exert a strong anticancer effect and additional studies will be needed to evaluate the different mechanisms between T24 and U937 cells.