In Vitro Radiosensitization of T47D and MDA-MB-231 Breast Cancer Cells with the Neoflavonoid Dalbergin

Background: Radiotherapy is a frequently used therapeutic modality for breast cancer. Dalbergin, a natural antioxidant, inhibits carcinogens and tumor progression. In the present study, we investigated the effect of Dalbergin on the response of T47D and MDA-MB-231 breast cancer cell lines to ionizing radiation. Method: In this experimental in vitro study, doubling time of T47D and MDAMB- 231 were obtained from the growth curve. The cytotoxic effect of Dalbergin on T47D and MDA-MB-231 breast cancer cells were estimated via MTT assay. To determine the clonogenic ability, we treated T47D and MDA-MB-231 with Dalbergin for 48 h prior to irradiation, subsequent to which a colony assay was performed. Realtime polymerase chain reaction was employed to determine the gene expression level. Results: Dalbergin inhibited proliferation of T47D and MDA-MB-231 in a timeand concentration-dependent manner. Additionally, the most appropriate time for the treatment of these types of cancer cells was found to be 48 h and the drug s concentration in both cell lines was different. The IC50 values of T47D and MDA-MB-231 cells were 0.001 and 0.0001 μM, respectively. Moreover, this drug radiaosensitizes both cell lines effectively compared with the radiation only. Finally, the gene expression level of p53, Bcl-2, and STAT3 were investigated in cancer cells. Conclusion: Dalbergin showed apoptotic effects probably through the STAT/p53 signaling pathway. Therefore, Dalbergin could be considered as a radiosensitizer and its effects may be owing to increased cell death.