Targeting p300/CBP abolishes HOXB13 loss-induced lipogenesis and tumor metastasis [ChIP-seq]

HOXB13 is a prostate-specific homeodomain transcription factor that is mainly known as an androgen receptor (AR) cofactor. Recent studies have revealed AR-independent roles of HOXB13 in recruiting HDAC3 to suppress lipogenic programs in prostate cancer (PCa). As such, HOXB13 down-regulation leads to lipid accumulation and tumor metastasis, the molecular mechanisms of which, however, are incompletely understood. Here, we demonstrate that p300/CBP co-occupies HOXB13/HDAC3-repressed lipogenic enhancers and is required for their activation and target gene expression upon HOXB13 loss. We found that HOXB13 is down-regulated in metastatic hormone-sensitive PCa compared to their matched primary prostate tumors. HOXB13 loss induces matrix metalloproteinases (MMPs), which mediate HOXB13-depleted cell motility. Critically, CCS1477, a pharmacological inhibitor of p300/CBP, abolished HOXB13-loss-induced lipid accumulation, MMP gene expression, cell motility in vitro, and tumor metastasis in vivo. Taken together, our results suggest HOXB13 as a significant metastasis suppressor and identify p300/CBP as critical therapeutic targets in HOXB13-low metastatic PCa. Overall design: To evaluate whether HOXB13 loss induces lipogenic enhancer activation through p300/CBP, we performed H3K27ac ChIP-seq in control and HOXB13-KD LNCaP cells with concomitant p300 and/or CBP KD, or treated with DMSO or 250nM CCS1477 for 24 hours