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Taxol, radiation, and oncogenic transformation
1Center for Radiological Research, College of Physicians & Surgeons, Columbia University, New York, New York 10032.
Abstract:
The novel antineoplastic drug taxol has been shown to be active clinically against several types of human tumors. With improvement in treatment strategy and the number of long-term survivors increasing, a question that needs to be addressed is the potential carcinogenic effect of the treatment in the induction of second malignancies. We show here that when tested using an in vitro assay for oncogenic transforming potential, taxol is ineffective in focus induction at doses significantly higher than those used in the clinic. However, taxol enhances the oncogenic potential of gamma-rays in a synergistic fashion. The fact that taxol blocks cells at the G2/M phases of the cell cycle may account for this interaction since G2/M are relatively radiosensitive phases of the cell cycle.
Insights
Taxol, an anti-cancer drug, does not appear to cause cancer on its own. However, it synergistically enhances the cancer-causing effects of gamma-rays by affecting cell cycle progression.
Area of Science:
- Oncology
- Cancer Research
- Drug Development
Background:
- Taxol (paclitaxel) is a novel antineoplastic drug with demonstrated clinical activity against various human tumors.
- Increasing long-term cancer survivors necessitate addressing the potential for treatment-induced second malignancies.
- Understanding the oncogenic transforming potential of taxol and its interaction with other cancer treatments is crucial.
Purpose of the Study:
- To evaluate the in vitro oncogenic transforming potential of taxol.
- To investigate the synergistic effects of taxol in combination with gamma-rays on oncogenic transformation.
- To explore the potential mechanisms behind taxol's interaction with radiation therapy.
Main Methods:
- An in vitro assay for oncogenic transforming potential was employed to test taxol.
- Taxol was tested at doses significantly higher than those used clinically.
- The combined effect of taxol and gamma-rays on oncogenic transformation was assessed.
Main Results:
- Taxol alone was ineffective in inducing oncogenic transformation, even at supra-clinical doses.
- Taxol demonstrated a synergistic enhancement of the oncogenic potential of gamma-rays.
- Taxol-induced cell cycle arrest at the G2/M phases may explain this synergistic interaction.
Conclusions:
- Taxol does not appear to possess intrinsic oncogenic transforming potential.
- Taxol enhances the oncogenic effects of gamma-rays, suggesting a potential for increased risk of second malignancies when used in combination therapy.
- The G2/M cell cycle blockade by taxol is a likely mechanism contributing to its radiosensitizing effect on oncogenesis.