Skin-cancer cells that enter senescence, a form of growth arrest that some have proposed using to combat cancer, can rally neighbouring cells to become more invasive.

Previous studies have hinted that, in addition to hindering cancer cells' growth, senescence might promote the spread of nearby cells. Corine Bertolotto at the French National Institute of Health and Medical Research in Nice and her team found that melanoma cells treated with chemotherapy drugs did senesce, but also secreted proteins associated with inflammation.

Exposing untreated melanoma cells to CCL2, one of these proteins, or to the medium in which treated cells had been grown prompted the cells to metastasize. An inflammatory pathway regulated by the protein NF-κB controlled the composition of secreted proteins, and when NF-κB was inhibited, the cellular secretions no longer promoted metastasis.

Genes Dev. doi:10.1101/gad.625811 (2011)