In vitro survival of MCF-7 breast cancer cells following combined treatment with ionizing radiation and mitoxantrone-mediated photodynamic therapy

This study evaluated the effects of mitoxantrone (MX) as a sensitizer following combined treatment with ionizing radiation and photodynamic therapy in the MCF-7 human breast cancer cell line. Cells were incubated with MX at different concentrations for 90 min and exposed to different fluence rates of non-coherent light and different dose rates of ionizing X-ray radiation in independent treatment groups. Additionally, the combined effects of chemotherapy, phototherapy, and radiotherapy were evaluated. The percent cell survival was investigated using the MIT assay. MX acted as both a photosensitizer and radiosensitizer. Furthermore, the use of 1 mu M MX in combination with PDT at 10 J/Cm-2 and 4 Gy of X-ray radiation strongly resulted in the death of cancer cells and reduced the percentage of viable cancer cells to 2.4 +/- 1.15. Our data demonstrated that the adverse effects of MX in combination with radiotherapy were partially abated, without a reduction in the efficacy of treatment. This new therapeutic avenue for breast cancer therapy merits further investigation using in vivo models for application in humans. (C) 2012 Elsevier B.V. All rights reserved.