Deregulation of hepatocyte nuclear factor 4 (HNF4)as a marker of epithelial tumors progression
Summary. Tissue-specific transcription factors forming the regulatory cascades which determine the specification and differentiation of epithelial cells during embryogenesis, play the central role in the control of functional and morphological properties of different cell types. Hepatocyte nuclear factors (HNFs) network is one of the most investigated tissue-specific regulatory systems which controls the specification and maintenance of differentiation of several epithelial cell types. Nuclear receptor HNF4α is one of the central elements of this regulatory network in the liver. We have found that deregulation of this gene is associated with rodent and human hepatocellular carcinoma (HCC) progression and induces the increase of proliferation rate, loss of epithelial morphology, dedifferentiation and metastasis. Restoration of HNF4α expression in dedifferentiated cells induced partial reversion of highly malignant phenotype both in vitro and in vivo. In human HCC samples HNF4α transcription was completely lost or significantly decreased in about 70% of HCCs, not associated with hepatitis B virus infection. Decrease of HNF4α isoforms expression correlated with poor prognosis. Thus we propose HNF4α is a candidate tumor suppressor for hepatic cells. Dysfunction of different HNFs was also reported in other epithelial tumors. We suppose that tissue-specific transcription factors which control the key steps of definite differentiation programs and are capable to receive and modulate extracellular signals can be considered as promising tumor suppressor candidates for their corresponding tissues.
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