The synergistic cytotoxic effects of doxorubicin and Viola odorata extract on human breast cancer cell line T47-D

Background: Breast cancer accounts for one-third of cancer cases in women. Doxorubicin (Dox) is one of the chemotherapeutical compounds widely used to treat breast cancer. Chemical drugs have several side effects and their continuous administration leads to drug resistance in patients. To decrease such side effects in cancer treatment, combination therapy as well as application of natural and herbal compounds has been taken into consideration. The aim of this study was to investigate the cytotoxic effect of Viola odorata (Vo) extract on T47-D human breast cancer cells, alone and in combination with Dox. Materials and Methods: The cytotoxic effects of V. odorata and Dox were studied by morphological examination and 3,(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Flowcytometric analysis was performed to determine the type of cell death. Moreover, scratch healing assay was conducted to investigate antimigration effect of V. odorata. Results: The results of MTT assay showed that V. odorata and Dox-induced cell death in T47-D cells in a dose- and time-dependent manner. Morphological analysis revealed that V. odorata and Dox-induced features of apoptotic cell death in T47-D cells. These results were confirmed by flow cytometry analysis. Scratch healing assay revealed that migration rate was reduced in the V. odorata- treated cells. Conclusions: Our findings suggest that components of V. odorata exert antitumor effects on human breast cancer and could be administered with lower doses of antitumor agent Dox, in combination therapy, to decrease its side effects.