CD155 downregulation synergizes with adriamycin to induce breast cancer cell apoptosis.

CD155 has been implicated in migration, invasion, proliferation and apoptosis of human cancer cells, and DNA damage response caused by chemotherapeutic agents or reactive oxygen species has been shown to attribute to CD155 induction. Adriamycin (Adr) is one of the most common chemotherapeutic drugs used to treat breast cancer. Here we reported that treatment with Adr upregulated CD155 expression on several in vitro cultured breast cancer cells and in breast cancer cell 4T1 xenografts. We also found that CD155 knockdown or Adr treatment induced apoptosis of in vitro cultured cancer cells and cancer cells in 4T1 xenografts, and a combination of CD155 knockdown with Adr treatment induced more cell death than either of them. Furthermore, we revealed that the combination of CD155 knockdown with Adr treatment suppressed the growth of 4T1 xenografts more significantly than them alone. In summary, our results demonstrate that CD155 downregulation synergizes with Adr to induce breast cancer cell apoptosis, thereby to suppress tumor growth. Our results also suggest that CD155 upregulation may be a mechanism underlying Adr resistance by breast cancer cells.