S100A8 as a potential therapeutic target for cancer metastasis.

Metastasis is a major cause of cancer-related deaths. Similar to the tumor microenvironment formation, the premetastatic niche develops in distant organs before the arrival of tumor cells. Elucidating the mechanism(s) underlying premetastatic niche formation could contribute to the establishment of effective therapeutic targets for metastasis. Our research indicates that primary tumors hijack Toll-like receptor 4 (TLR4) signaling to establish a premetastatic niche in the lungs by utilizing an endogenous ligand S100A8. S100A8 is expressed not only in immune cells but also in various types of tumor cells. By focusing on S100A8 as a therapeutic target, we identified at least three multivalent S100A8 inhibitory peptides. Here, we review the tumor-promoting role of S100A8-mediated TLR4 signaling and propose S100A8 as a potential therapeutic target for aggressive cancer.