Skip to Main content Skip to Navigation
Journal articles

Letrozole sensitizes breast cancer cells to ionizing radiation.

Abstract : INTRODUCTION: Radiotherapy (RT) is considered a standard treatment option after surgery for breast cancer. Letrozole, an aromatase inhibitor, is being evaluated in the adjuvant setting. We determined the effects of the combination of RT and letrozole in the aromatase-expressing breast tumour cell line MCF-7CA, stably transfected with the CYP19 gene. 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.
Complete list of metadatas

Cited literature [31 references]  Display  Hide  Download

https://www.hal.inserm.fr/inserm-00094862
Contributor : Françoise Maylin <>
Submitted on : Friday, September 15, 2006 - 10:41:25 AM
Last modification on : Wednesday, August 14, 2019 - 5:36:06 PM
Long-term archiving on: : Thursday, September 20, 2012 - 10:41:21 AM

Identifiers

Collections

Citation

David Azria, Christel Larbouret, Severine Cunat, Mahmut Ozsahin, Sophie Gourgou, et al.. Letrozole sensitizes breast cancer cells to ionizing radiation.. Breast Cancer Research, BioMed Central, 2005, 7, pp.R156-63. ⟨10.1186/bcr969⟩. ⟨inserm-00094862⟩

Share

Metrics

Record views

296

Files downloads

440