The role of HNF4α in adenocarcinoma.

Hepatocyte nuclear factor 4 alpha (HNF4α) is a conserved nuclear receptor that governs epithelial identity and metabolic homeostasis across endoderm-derived tissues. In cancer, HNF4α can function as either an oncogene or a tumor suppressor. In colorectal and hepatocellular carcinoma, reduced HNF4α activity accompanies loss of differentiation and tumor progression, consistent with tumor-suppressive functions. In contrast, in pancreatic ductal adenocarcinoma, invasive mucinous adenocarcinoma, and other lineage-defined epithelial tumors, HNF4α can also participate in transcriptional programs that sustain malignant identity, metabolic adaptation, and therapeutic resistance. However, these effects are highly context-dependent and do not imply a uniformly oncogenic role in these tumor types. These divergent functions are shaped by isoform usage, chromatin state, epigenetic regulation, metabolic cues, and transcription factor networks. Rather than acting as a classical oncogene or tumor suppressor in all settings, HNF4α is better understood as a context-dependent regulator of lineage state whose activity may either restrain tumor progression or support tumor maintenance. This mini review highlights the molecular mechanisms that shape HNF4α activity, including isoform biology and epigenetic control, and discusses emerging strategies for selectively inhibiting HNF4α in dependency states or restoring its differentiation-promoting functions in tumors where it is lost.