HDAC5 depletion promotes hyper-acetylation of FOXA1 and potentiates HIF1α transcriptional activation in pancreatic cancer.

The biological significance of forkhead box A1 (FOXA1) in non-steroid-driven malignancies, such as pancreatic ductal adenocarcinoma (PDAC), has garnered increasing recognition. It assumes a pivotal role in regulating critical processes such as PDAC cell lineage, metabolism, and metastasis. However, its regulatory mechanisms remain elusive. Here, we demonstrate that histone deacetylase 5 (HDAC5) mediates the deacetylation of FOXA1 at lysine residue 270 (K270), leading to repression of FOXA1's global chromatin occupancy. In HDAC5-loss PDAC, K270 hyper-acetylated FOXA1 is reprogrammed to the transcription start sites (TSSs) of HIF1α-targeted genes, functioning as a pioneer factor of HIF1α signaling. Additionally, we show that HDAC5 antagonizes LSD1-mediated FOXA1 activation by converging on the dynamic equilibrium of acetylation-methylation transition at K270. Pharmacological inhibition of HIF1α/LSD1 suppresses the growth and progression of HDAC5-deficient PDAC in in vivo and in vitro models. Our study reveals the role of FOXA1 as a pioneer factor of HIF1α in PDAC, providing potential therapeutic strategies for HDAC5-deficient PDAC.