Foxa1 and Foxa2 are essential for sexual dimorphism in liver cancer

Hepatocellular carcinoma (HCC) is sexually dimorphic in both rodents and humans, with significantly higher incidence in males, an effect that is dependent on sex hormones. The molecular mechanisms by which estrogens prevent and androgens promote liver cancer remain unclear. Here, we discover that sexually dimorphic HCC is completely reversed in Foxa1- and Foxa2-deficient mice after diethylnitrosamine-induced hepatocarcinogenesis. Coregulation of target genes by Foxa1/a2 and either the estrogen receptor (ERα) or the androgen receptor (AR) was increased during hepatocarcinogenesis in normal female or male mice, respectively, but was lost in Foxa1/2-deficient mice. Thus, both estrogen-dependent resistance to and androgen-mediated facilitation of HCC depend on Foxa1/2. Strikingly, single nucleotide polymorphisms at FOXA2 binding sites reduce binding of both FOXA2 and ERα to their targets in human liver and correlate with HCC development in women. Thus, Foxa factors and their targets are central for the sexual dimorphism of HCC.     

Changes at the nuclear lamina alter binding of pioneer factor Foxa2 in aged liver

Increasing evidence suggests that regulation of heterochromatin at the nuclear envelope underlies metabolic disease susceptibility and age‐dependent metabolic changes, but the mechanism is unknown. Here, we profile lamina‐associated domains (LADs) using lamin B1 ChIP‐Seq in young and old hepatocytes and find that, although lamin B1 resides at a large fraction of domains at both ages, a third of lamin B1‐associated regions are bound exclusively at each age in vivo. Regions occupied by lamin B1 solely in young livers are enriched for the forkhead motif, bound by Foxa pioneer factors. We also show that Foxa2 binds more sites in Zmpste24 mutant mice, a progeroid laminopathy model, similar to increased Foxa2 occupancy in old livers. Aged and Zmpste24‐deficient livers share several features, including nuclear lamina abnormalities, increased Foxa2 binding, de‐repression of PPAR‐ and LXR‐dependent gene expression, and fatty liver. In old livers, additional Foxa2 binding is correlated to loss of lamin B1 and heterochromatin (H3K9me3 occupancy) at these loci. Our observations suggest that changes at the nuclear lamina are linked to altered Foxa2 binding, enabling opening of chromatin and de‐repression of genes encoding lipid synthesis and storage targets that contribute to etiology of hepatic steatosis.