Nature Cell Biol. doi:10.1038/ncb1794 (2008)

Before travelling to new organs — or metastasizing — some cancers send chemical signals to prepare the target organ for their arrival.

Yoshiro Maru and his colleagues at the Tokyo Women's Medical University in Japan had previously found that primary tumours in mice secrete growth factors that stimulate lung cells to produce chemoattractant proteins. These recruit white blood cells into the lungs, and the resulting inflammation recruits cancer cells to the site.

The team now reports that the chemoattractants involved induce the synthesis of serum amyloid A3 in lung cells. This protein attracts and activates white blood cells, setting up a state of chronic inflammation that facilitates tumour cell invasion. Antibodies against serum amyloid A3 blocked metastasis.