Introduction Breast cancer is one of the most common cancers among women in the world. Different therapeutic strategies such as radiotherapy, chemotherapy and surgery have been used either individually or in combination. Oncolytic virotherapy is a rising treatment methodology, which utilizes replicating viruses to eliminate tumor cells. The aim of this study was to investigate the oncolytic activity of live-attenuated poliovirus in breast cancer cell lines. Materials and methods The CD155 expression level in two human breast cancer cell lines and a normal breast cell line were evaluated using real-time PCR and flow cytometry. Virus titration was assessed by TCID50. The cytotoxicity of poliovirus on cell line and apoptosis response was investigated by MTT and Caspase 8 and Caspase 9 ELISA kits, respectively. Results This study showed that CD155 gene was expressed significantly (p = 0.001) higher in both human breast cancer cell lines compared to the normal cell line. The protein expression level of CD155 was 98.1%, 96.7%, in MDA_MB231 and MCF_7 cell lines, respectively, whereas the CD155 expression level was 1.3% in MCF_10A. The cytopathic effect of poliovirus in breast cancer cell lines was significantly higher than normal cells (p < 0.05). Extrinsic apoptosis response was more effective than intrinsic apoptosis in both breast cancer cell lines (p < 0.05). Conclusion In summary, administration of live-attenuated poliovirus can be a promising treatment to breast cancer. However, in vitro and in vivo studies will be required to evaluate the safety of this strategy.
