Abstract | INTRODUCTION: METHODS: Irradiations were performed using a cobalt-60 source with doses ranging from 0 to 4 Gy. Cells were incubated with androstenedione in the presence or absence of letrozole. Effects of treatment were evaluated using clonogenic assays, tetrazolium salt colorimetric (MTT) assays, and cell number determinations. Cell-cycle analyses were conducted using flow cytometry. RESULTS: The survival fraction at 2 Gy was 0.66 for RT alone and was 0.44 for RT plus letrozole (P = 0.02). Growth of MCF-7CA cells as measured by the cell number 6 days after radiotherapy (2 and 4 Gy) was decreased by 76% in those cells treated additionally with letrozole (0.7 microM) compared with those receiving radiotherapy alone (P = 0.009). Growth inhibition, assessed either by cell number (P = 0.009) or by the MTT assay (P = 0.02), was increased after 12 days of the combination treatment. Compared with radiation alone, the combination of radiation and letrozole produced a significant decrease in radiation-induced G2 phase arrest and a decrease of cells in the S phase, with cell redistribution in the G1 phase. CONCLUSIONS: These radiobiological results may form the basis for concurrent use of letrozole and radiation as postsurgical adjuvant therapy for breast cancer.
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Authors | David Azria, Christel Larbouret, Severine Cunat, Mahmut Ozsahin, Sophie Gourgou, Pierre Martineau, Dean B Evans, Gilles Romieu, Pascal Pujol, Andre Pèlegrin |
Journal | Breast cancer research : BCR
(Breast Cancer Res)
Vol. 7
Issue 1
Pg. R156-63
( 2005)
ISSN: 1465-542X [Electronic] England |
PMID | 15642164
(Publication Type: Journal Article)
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Chemical References |
- Antineoplastic Agents
- Nitriles
- Radiation-Sensitizing Agents
- Triazoles
- Letrozole
- Aromatase
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Topics |
- Antineoplastic Agents
(pharmacology)
- Aromatase
(biosynthesis, genetics)
- Breast Neoplasms
(pathology)
- Cell Cycle
(drug effects, radiation effects)
- Cell Survival
- Female
- Flow Cytometry
- Humans
- Letrozole
- Nitriles
(pharmacology)
- Radiation-Sensitizing Agents
(pharmacology)
- Radiotherapy, Adjuvant
- Transfection
- Triazoles
(pharmacology)
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