Synergistic Anticancer Effects of Silibinin and Chrysin in T47D Breast Cancer Cells

Objective: Breast cancer is one of the most significant causes of female cancer death worldwide. Although several chemotherapeutics have been developed to treat this type of cancer, issues remain such as low survival rates and high reoccurrence after chemotherapy and radiotherapy. To explore a chemopreventive approach to enhancing breast cancer treatment efficacy, the antiproliferative effects of a combination of chrysin and silibinin, two herbal substances, in T47D breast cancer cells were assessed. Materials and Methods: Cytotoxicity of the agents singly and in combination was evaluated by MTT assay. Also, qRT-PCR was used to measure the expression levels of hTERT and cyclin D1 genes after 48 h treatment. Results: Cell viability assays revealed that chrysin or silibinin alone inhibited proliferation in a dose and time-dependent manner, and combining the drugs synergistically induced growth inhibition in the breast cancer cell line. The precise nature of this interaction was further analyzed by the median-effect method, where the combination indices (CI) were <1 for combination treatments, indicating synergism regarding T47D cell proliferation. qPCR results showed that the drug combination also synergistically down-regulated the mRNA levels of hTERT and cyclin D1 at all used concentrations compared with the drugs used alone after 48 h treatment (P ≤ 0.05). Conclusion: The data provide evidence that synergistic antiproliferative effects of Chrysin and Silibinin are linked to the down-regulation of cyclin D1 and hTERT genes, and suggest that their combination may have therapeutic value in treatment of breast cancer.