c-myb mediates inflammatory reaction against oxidative stress in human breast cancer cell line, MCF-7

Emerging evidence suggests that oncogenes play an important role in the inflammatory reactions in cancer cells, but the precise molecular and cellular mechanisms linking the oncogenes to inflammation is unclear. This study examined the contribution of proto-oncogene c-myb to inflammation in MCF-7 breast cancer cells. An inflammatory response was elicited directly by the cells using an in vitro culture system whereby the cells were exposed to H ₂O ₂. Upon exposure to H ₂O ₂, the cells showed a local inflammatory response, as evidenced by matrix metalloproteinases (MMPs) and ICAM-1 expression. Significant up-regulation of the proto-oncogene c-myb also was observed under inflammatory conditions. c-myb, overexpressed in the cells by transducing with Ad/c-myb, showed an increase in MMPs and ICAM-1 expression under H ₂O ₂ stimulation. Despite H ₂O ₂ stimulation, the c-myb down-regulated cells by c-myb siRNA inhibit the expression of MMPs and ICAM-1. Among the MAPKs, ERK1/2 and SAPK/JNK were activated by the H ₂O ₂ treatment. Interestingly, the H ₂O ₂-induced activation of ERK1/2 and SAPK/JNK was inhibited by siRNA c-myb. These results suggest that breast cancer cells may play a significant role in sustaining and amplifying the inflammation process through the activation of c-myb, which results in the activation of the ERK1/2 and SAPK/JNK pathway. This condition highlights the potential link between inflammation and its involvement in promoting breast cancer proliferation.