3,3′-Diindolylmethane: A Promising Sensitizer of γ-Irradiation

Purpose. Radiotherapy is an effective treatment modality in the clinical treatment of breast cancer. The present work investigated the effect of 3,3′-diindolylmethane (DIM) on γ-irradiation sensitizing human breast carcinoma. Methods. Cell survival, intracellular ROS levels, cell cycle distribution, cell apoptosis, and expression of proteins related to apoptosis were measured with MTT assays, flow cytometry, and Western blot analysis, respectively. Results. In vitro DIM plus γ-irradiation arrested the activity of G2/M phase cell cycle, increased intracellular ROS level, significantly suppressed PARP (poly ADP-ribose polymerase), and enhanced γ-irradiation-induced apoptosis, thereby inhibiting the proliferation of MCF-7 cells. Conclusion. These data provide a rationale for the use of DIM as a promising sensitizer of γ-irradiation.