Genetics and epigenetics of direct and indirect radiation responses in normal mammary and breast cancer cells

The successful approach for decreasing breast cancer fatalities depends upon reliable diagnostic screening and optimal treatment modalities. Ionizing radiation is widely used for both screening and therapeutic procedures. The main aim of this study was to analyze the effect of low (diagnostic) and high (treatment) doses of ionizing radiation on healthy breast cells, breast cancer cells, and cancer cells resistant to common drug therapies. The results presented here show that ionizing radiation initiates immune and apoptotic response in normal cells, and causes epigenetic alterations that may lead to genomic instability. In addition, our results demonstrate differential dose response to radiation in MCF-7 cells, and decreased sensitivity to radiation in tamoxifen-resistant MCF-7 cells. Our results may serve as foundation for the future analysis of the mechanisms of radiation responses of mammary gland tissues, and as an additional step for future analysis of effectiveness of combination therapy