In a recent issue of Cell, William Greenleaf, Monte Winslow and colleagues have characterized differences within primary and metastatic tumors in an engineered mouse model of small cell lung cancer (SCLC). Many patients with SCLC have inoperable metastases at diagnosis making treatment very challenging.

Examining the primary tumor and tumor cells that spread to the liver, the researchers focused on “open chromatin,” regions on each chromosome configured for active gene expression. The comparative study identified enhanced activity of the gene NFIB, associated with metastasis, and functional tests demonstrated that NFIB is required for metastasis, but not for primary tumor growth.

The study extends our understanding of how cancer spreads and identifies NFIB as a potential target for therapeutic development.