科研之友
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摘要
Background: Hepatocyte Nuclear Factor 1 alpha (HNF1 alpha) is an atypical homeodomain-containing transcription factor that transactivates liver-specific genes including albumin, alpha 1-antitrypsin and alpha and beta fibrinogen. Biallelic inactivating mutations of HNF1A have been frequently identified in hepatocellular adenomas (HCA), rare benign liver tumors usually developed in women under oral contraceptives, and in rare cases of hepatocellular carcinomas developed in non-cirrhotic liver. HNF1 alpha-mutated HCA (H-HCA) are characterized by a marked steatosis and show activation of glycolysis, lipogenesis, translational machinery and mTOR pathway. We studied the consequences of HNF1 alpha silencing in hepatic cell lines, HepG2 and Hep3B and we reproduced most of the deregulations identified in H-HCA.
Methods: We transfected hepatoma cell lines HepG2 and Hep3B with siRNA targeting HNF1 alpha and obtained a strong inhibition of HNF1 alpha expression. We then looked at the phenotypic changes by microscopy and studied changes in gene expression using qRT-PCR and Western Blot.
Results: Hepatocytes transfected with HNF1 alpha siRNA underwent severe phenotypic changes with loss of cell-cell contacts and development of migration structures. In HNF1 alpha-inhibited cells, hepatocyte and epithelial markers were diminished and mesenchymal markers were over-expressed. This epithelial-mesenchymal transition (EMT) was related to the up regulation of several EMT transcription factors, in particular SNAIL and SLUG. We also found an overexpression of TGF beta 1, an EMT initiator, in both cells transfected with HNF1 alpha siRNA and H-HCA. Moreover, TGF beta 1 expression is strongly correlated to HNF1 alpha expression in cell models, suggesting regulation of TGF beta 1 expression by HNF1 alpha.
Conclusion: Our results suggest that HNF1 alpha is not only important for hepatocyte differentiation, but has also a role in the maintenance of epithelial phenotype in hepatocytes.
- 出版日期2011-10-5
