SERPINB13 is a novel RUNX1 target gene.

RUNX1 is a critical transcription factor during embryogenesis and neoplastic disease. To identify novel transcriptional targets of RUNX1 in the context of chromatin, we performed genome wide location analysis (ChIP-on-chip). Here we report that SERPINB13, a gene downregulated in head and neck cancers, is a novel RUNX1transcriptional target. RUNX1 binds the SERPINB13 promoter in chromatin to repress its transcription. Mutation of either RUNX1 binding site in the SERPINB13 promoter increased the activity of the promoter. Finally, overexpression of RUNX1 and concomitant decrease in SERPINB13 expression led to increased activity of cathepsin K, an enzyme inhibited by SERPINB13. These data demonstrate that RUNX1 is an important regulator of SERPINB13 and cathepsin K activity.