Global analysis of DNA methylation in early-stage liver fibrosis.

BACKGROUND: Liver fibrosis is caused by chemicals or viral infection. The progression of liver fibrosis results in hepatocellular carcinogenesis in later stages. Recent studies have revealed the importance of DNA hypermethylation in the progression of liver fibrosis to hepatocellular carcinoma (HCC). However, the importance of DNA methylation in the early-stage liver fibrosis remains unclear. METHODS: To address this issue, we used a pathological mouse model of early-stage liver fibrosis that was induced by treatment with carbon tetrachloride (CCl4) for 2 weeks and performed a genome-wide analysis of DNA methylation status. This global analysis of DNA methylation was performed using a combination of methyl-binding protein (MBP)-based high throughput sequencing (MBP-seq) and bioinformatic tools, IPA and Oncomine. To confirm functional aspect of MBP-seq data, we complementary used biochemical methods, such as bisulfite modification and in-vitro-methylation assays. RESULTS: The genome-wide analysis revealed that DNA methylation status was reduced throughout the genome because of CCl4 treatment in the early-stage liver fibrosis. Bioinformatic and biochemical analyses revealed that a gene associated with fibrosis, secreted phosphoprotein 1 (Spp1), which induces inflammation, was hypomethylated and its expression was up-regulated. These results suggest that DNA hypomethylation of the genes responsible for fibrosis may precede the onset of liver fibrosis. Moreover, Spp1 is also known to enhance tumor development. Using the web-based database, we revealed that Spp1 expression is increased in HCC. CONCLUSIONS: Our study suggests that hypomethylation is crucial for the onset of and in the progression of liver fibrosis to HCC. The elucidation of this change in methylation status from the onset of fibrosis and subsequent progression to HCC may lead to a new clinical diagnosis.

Estrogen regulates tumor growth through a nonclassical pathway that includes the transcription factors ERß and KLF5.

Clinical evidence suggests that antiestrogens inhibit the development of androgen-insensitive prostate cancer. Here, we show that the estrogen receptor ß (ERß) mediates inhibition by the antiestrogen ICI 182,780 (ICI) and its enhancement by estrogen. ERß associated with gene promoters through the tumor-suppressing transcription factor KLF5 (Krüppel-like zinc finger transcription factor 5). ICI treatment increased the recruitment of the transcription coactivator CBP [CREB (adenosine 3',5'-monophosphate response element-binding protein)-binding protein] to the promoter of FOXO1 through ERß and KLF5, which enhanced the transcription of FOXO1. The increase in FOXO1 abundance led to anoikis in prostate cancer cells, thereby suppressing tumor growth. In contrast, estrogen induced the formation of complexes containing ERß, KLF5, and the ubiquitin ligase WWP1 (WW domain containing E3 ubiquitin protein ligase 1), resulting in the ubiquitination and degradation of KLF5. The combined presence of KLF5 and ERß positively correlated with longer cancer-specific survival in prostate cancer patients. Our results demonstrate that estrogens and antiestrogens affect prostate tumor growth through ERß-mediated regulation of KLF5.

Novel nucleolar pathway connecting intracellular energy status with p53 activation.

In response to a shortage of intracellular energy, mammalian cells reduce energy consumption and induce cell cycle arrest, both of which contribute to cell survival. Here we report that a novel nucleolar pathway involving the energy-dependent nucleolar silencing complex (eNoSC) and Myb-binding protein 1a (MYBBP1A) is implicated in these processes. Namely, in response to glucose starvation, eNoSC suppresses rRNA transcription, which results in a reduction in nucleolar RNA content. As a consequence, MYBBP1A, which is anchored to the nucleolus via RNA, translocates from the nucleolus to the nucleoplasm. The translocated MYBBP1A induces acetylation and accumulation of p53 by enhancing the interaction between p300 and p53, which eventually leads to the cell cycle arrest (or apoptosis). Taken together, our results indicate that the nucleolus works as a sensor that transduces the intracellular energy status into the cell cycle machinery.

Beta1-adrenergic receptor mediation in the lichen glucan PB-2-induced enhancement of long-term potentiation in the rat dentate gyrus in vivo.

The mechanism underlying the enhancement of long-term potentiation (LTP) induced by the systemic administration of PB-2, an alpha(1-3)(1-4)glucan-containing fraction extracted from the lichen Flavoparmelia baltimorensis and a putative LTP-enhancing agent, was investigated in the rat dentate gyrus in vivo. Particular attention was paid to the role of adrenaline beta-receptors. An intravenous (i.v.) injection of PB-2 enhanced the induction of LTP, which was in turn inhibited by an i.v. injection of the adrenaline beta1-receptor antagonist atenolol. An intracerebroventricular injection of atenolol did not affect the induction of LTP, but completely suppressed the PB-2-induced enhancement of LTP. The infusion of atenolol into the recording site attenuated the PB-2-induced facilitation of LTP. These results suggest that the adrenaline beta1-receptors contribute to the enhancement of LTP induced by the systemic administration of PB-2, and that the functional beta1-receptors are located both centrally and peripherally.