Sequential dependent enhancement of caspase activation and apoptosis by flavopiridol on paclitaxel-treated human gastric and breast cancer cells Journal Article
| Authors: | Motwani, M.; Delohery, T. M.; Schwartz, G. K. |
| Article Title: | Sequential dependent enhancement of caspase activation and apoptosis by flavopiridol on paclitaxel-treated human gastric and breast cancer cells |
| Abstract: | Although in the past 10 years paclitaxel has emerged as a successful drug in cancer therapy, the overall response rate to this drug in patients with advanced metastatic disease remains low. Therefore, an understanding of the mechanism of the effect of paclitaxel on inducing apoptosis and the discovery of new ways to enhance the effect of paclitaxel will be critical to improving the therapeutic efficiency of this drug. In the present studies, we have determined that the cyclin-dependent kinase inhibitor flavopiridol significantly enhances paclitaxel-induced apoptosis in the human gastric and breast cancer cell lines MKN-74 and MCF-7. Flavopiridol enhances paclitaxel- induced apoptosis only when administered after paclitaxel treatment. The activation of caspases, specifically caspase 3, is enhanced by flavopiridol on paclitaxel-treated cells. In accordance with this, poly(ADP-ribose) polymerase cleavage is enhanced in combination therapy relative to single- agent paclitaxel. The induction of apoptosis, activation of caspase 3, and poly(ADP-ribose) polymerase cleavage in treatment regimens with paclitaxel and paclitaxel followed by flavopiridol were reversed by treatment with the caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone, which supports the notion that caspases are the executioners of apoptosis in these processes. Paclitaxel alone causes transient mitotic arrest with activation of cdc-2 kinase. Cells exit mitosis in a specific time window without cytokinesis, with a decrease in cdc-2 kinase activity and MPM-2 labeling. Flavopiridol accelerates the mitotic exit when administered after paclitaxel treatment in association with a more rapid decrease in MPM-2 labeling. In contrast, pretreatment with flavopiridol prevents cells from entering mitosis by inhibiting cdc-2 kinase activity, thus antagonizing the paclitaxel effect. Therefore, in this study we show that potentiation of paclitaxel-induced apoptosis by flavopiridol is highly sequence dependent, such that mitotic entry and cdc-2 kinase activation by paclitaxel must precede flavopiridol therapy, and the synergistic effect of flavopiridol on paclitaxel-treated cells is due to enhancement in caspase activation. |
| Keywords: | controlled study; human cell; drug potentiation; antineoplastic agents; paclitaxel; mitosis; metastasis; apoptosis; cancer cell culture; enzyme activation; tumor cells, cultured; caspase; caspase inhibitor; caspases; breast neoplasms; drug mechanism; breast carcinoma; flavonoids; flavopiridol; piperidines; cyclin b; cyclin dependent kinase; cyclin dependent kinase inhibitor; retinoblastoma protein; stomach carcinoma; stomach neoplasms; drug interactions; cdc2 protein kinase; poly(adenosine diphosphate ribose); humans; human; priority journal; article; benzyloxycarbonylphenylalanylalanyl fluoromethyl ketone; poly adenosine diphosphate ribose |
| Journal Title: | Clinical Cancer Research |
| Volume: | 5 |
| Issue: | 7 |
| ISSN: | 1078-0432 |
| Publisher: | American Association for Cancer Research |
| Date Published: | 1999-07-01 |
| Start Page: | 1876 |
| End Page: | 1883 |
| Language: | English |
| PUBMED: | 10430095 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | Article -- Export Date: 16 August 2016 -- Source: Scopus |
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