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Fluoropyrimidine-mediated radiosensitization depends on cyclin E-dependent kinase activation
T S Lawrence1, M A Davis, T L Loney
1Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, Michigan 48109. USA.
Cancer Research
|July 15, 1996
Summary
Fluoropyrimidines radiosensitize colon cancer cells by promoting S phase progression. This occurs via a p53-independent G1-S checkpoint, linked to cyclin E-dependent kinase activity, enhancing radiosensitization.
Area of Science:
- Oncology
- Molecular Biology
- Radiotherapy
Background:
- Fluoropyrimidines are chemotherapy drugs used in cancer treatment.
- These drugs can enhance the effects of radiation therapy (radiosensitization).
- The precise mechanisms of fluoropyrimidine-induced radiosensitization are not fully understood.
Purpose of the Study:
- To investigate the role of cell cycle progression and kinase activity in fluoropyrimidine-mediated radiosensitization.
- To determine if the p53 tumor suppressor pathway is involved in this process.
Main Methods:
- Human colon cancer cell lines (HT29 and SW620) were treated with fluorodeoxyuridine.
- Thymidylate synthase inhibition and cell cycle progression were monitored.
- Cyclin E-dependent kinase activity was measured.
Main Results:
- HT29 cells progressed into S phase and showed increased cyclin E-dependent kinase activity.
- SW620 cells arrested at the G1-S boundary with no change in kinase activity.
- Both cell lines share the same p53 mutation.
Conclusions:
- Fluorodeoxyuridine-induced radiosensitization is mediated by S phase progression.
- A p53-independent G1-S checkpoint appears to regulate this process.
- Elevated cyclin E-dependent kinase activity is associated with S phase entry and radiosensitization.