Specific expression and regulation of hepassocin in the liver and down-regulation of the correlation of HNF1alpha with decreased levels of hepassocin in human hepatocellular carcinoma.
Hepassocin (HPS), is a liver-specific gene with mitogenic activity on isolated hepatocytes. It is up-regulated following partial hepatectomy and down-regulated frequently in heptocellular carcinoma (HCC). However, very little is known about the HPS transcription regulation mechanism. In this study, we identified HNF1alpha (hepatocyte nuclear factor-1alpha) as an important liver-specific cis-acting element for HPS using in vivo luciferase assays. Deletion of the HNF1 binding site not only led to a complete loss of HPS promoter activity in vivo but also abolished the induction of the HPS promoter by HNF1alpha. An electrophoretic mobility shift assay demonstrated that HNF1alpha interacted with the HPS gene promoter in vitro. Chromatin immunoprecipitation showed that HNF1alpha interacted with HMGB1 and CREB-binding protein, and all of them were recruited to the HPS promoter in vivo. Moreover, HNF1alpha expression was lower in HCC cell lines and tissues and correlated significantly with the down-regulation of HPS expression. Re-expression of HNF1alpha in human hepatoma HepG2 cells reinduced HPS expression. In contrast, knockdown of endogenous HNF1alpha expression by small interfering RNA resulted in a significant reduction of HPS expression. Furthermore, we found that partial hepatectomy and IL-6 significantly induced promoter activity of HPS, depending on STAT3 and HNF1 binding sites in the HPS promoter. These results demonstrate that the HNF1 binding site and HNF1alpha are critical to liver-specific expression of HPS, and down-regulation or loss of HNF1alpha causes, at least in part, the transcriptional down-regulation of HPS in HCC.
Yu
Hai-Tao
HT
Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China.
Yu
Miao
M
Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China.
Li
Chang-Yan
CY
Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China.
Zhan
Yi-Qun
YQ
Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China.
Xu
Wang-Xiang
WX
Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China.
Li
Yong-Hui
YH
Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China.
Li
Wei
W
Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China.
Wang
Zhi-Dong
ZD
Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China.
Ge
Chang-Hui
CH
Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China.
Yang
Xiao-Ming
XM
Beijing Institute of Radiation Medicine, Beijing 100850, China; State Key Laboratory of Proteomics, Beijing 100850, China; School of Chemical Engineering and Technology of Tianjin University, Tianjin 300072, China. Electronic address: xmyang2@nic.bmi.ac.cn.
D000818:Animals; D050882:CREB-Binding Protein / Q000235:genetics / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D015536:Down-Regulation; D005340:Fibrinogen; D017353:Gene Deletion; D015972:Gene Expression Regulation, Neoplastic; D024243:HMGB1 Protein / Q000235:genetics / Q000378:metabolism; D051538:Hepatocyte Nuclear Factor 1-alpha / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D011485:Protein Binding; D020218:Response Elements; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
C485894:FGL1 protein, human; D024243:HMGB1 Protein; C496487:HNF1A protein, human; D051538:Hepatocyte Nuclear Factor 1-alpha; C496488:Hnf1a protein, mouse; C508600:IL6 protein, human; D015850:Interleukin-6; D009363:Neoplasm Proteins; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C494087:Stat3 protein, mouse; D005340:Fibrinogen; D050882:CREB-Binding Protein; C494363:CREBBP protein, human