Related Experiment Videos
Taxol: a novel radiation sensitizer
R B Tishler1, P B Schiff, C R Geard
1Department of Radiation Oncology, College of Physicians and Surgeons, Columbia University, New York, NY.
Abstract:
The investigational antineoplastic agent, taxol, a natural product from the yew, Taxus sp. L., is currently being evaluated in a series of Phase II clinical trials. To date, the drug has shown activity against ovarian cancer, lung cancer, and melanoma. Taxol is a potent microtubule stabilizing agent that selectively blocks cells in the G2 and M phases of the cell cycle and is cytotoxic in a time-concentration dependent manner. It is well known from radiobiological principles that G2 and M are the most radiosensitive phases of the cell cycle. On the rationale that taxol could function as a cell-cycle selective radiosensitizer, we examined the consequences of combined drug-radiation exposures on the human grade 3 astrocytoma cell line, G18. Survival curve analysis shows a dramatic interaction between taxol and ionizing radiation with the degree of enhanced cell killing dependent on taxol concentration and on the fraction of cells in the G2 or M phases of the cell cycle. The sensitizer enhancement ratio (SER) for 10 nM taxol at 10% survival is approximately 1.8. These results obtained with cycling aerated radioresistant brain tumor cells indicate that significant advantage may derive from appropriate time-concentration dependent interactions in combined modality protocols.
Insights
Investigational antineoplastic agent taxol enhances radiation therapy by selectively targeting cancer cells in the G2 and M phases. This combination therapy shows significant potential for improved cancer treatment outcomes.
Area of Science:
- Oncology
- Cell Biology
- Radiotherapy
Background:
- Taxol (paclitaxel) is an antineoplastic agent derived from yew trees.
- It functions as a microtubule stabilizing agent, arresting cells in G2 and M phases.
- G2 and M phases are known to be the most radiosensitive cell cycle stages.
Purpose of the Study:
- To investigate taxol's potential as a cell-cycle selective radiosensitizer.
- To evaluate the combined effects of taxol and ionizing radiation on astrocytoma cells.
Main Methods:
- Exposure of human grade 3 astrocytoma cells (G18) to taxol and ionizing radiation.
- Survival curve analysis to assess cell killing efficacy.
- Determination of sensitizer enhancement ratio (SER).
Main Results:
- A significant synergistic interaction was observed between taxol and ionizing radiation.
- Enhanced cell killing was dependent on taxol concentration and cell cycle phase distribution.
- A sensitizer enhancement ratio (SER) of approximately 1.8 was achieved with 10 nM taxol.
Conclusions:
- Taxol acts as an effective cell-cycle selective radiosensitizer.
- Combined taxol-radiation therapy demonstrates potential for treating radioresistant brain tumors.
- Optimized timing and concentration of taxol are crucial for combined modality protocols.