Analysis of expressional changes of liver enriched transcription factors during occurrence and development of hepatocellular carcinoma, its application to pathological diagnosis and gene therapy

几个肝脏富集的转录因子被确定，其表达的调控已经众所周知。我们发现，在从高分化肝细胞癌（HCC）向低分化HCC的去分化过程中，HNF-1 α表达下降，而HNF-1β保持不变。我们还表征了未分化HCC细胞系，称为ETK-1，其具有像肝干细胞一样的双向分化能力，既可分化为肝细胞，称为MEK，也可分化为胆管上皮细胞，ETK-1细胞既不表达HNF-1α，也不表达HNF-4。MEK细胞表达HNF-1α和HNF-4。NEC仅表达HNF-4，不表达HNF-1α。ETK-1和NEC不表达转甲状腺素蛋白、白蛋白、甲胎蛋白等肝特异性基因，而MEK表达所有肝特异性基因。本研究主要探讨NEC表达HNF-4但不表达肝特异性基因或HNF-1α的机制。荧光 关于我们 在NEC细胞中，HNF-4定位于细胞质而非细胞核。HNF-4不能从细胞质转移到细胞核，这可能导致其作为转录调节因子的功能缺陷。我们还分析了在HCC去分化过程中参与肝富集转录调控的信号转导分子，对手术切除的HCC组织进行免疫组化和western-和north-blot分析表明，SAP-1的过度表达，SAP-1在高分化肝癌中的表达，在肝癌去分化过程中表达下降。转基因诱导SAP-1在低分化肝癌细胞系中过表达，引起肝癌再分化，并抑制细胞增殖和侵袭。SAP-1可能通过肝细胞分化参与HCC的演变和转移。少

Several liver enriched transcription factors were identified and the regulation of their expressions has been well known. We showed that HNF-1a expression decreased, although HNF-1β remained unchanged, during dedifferentiation from well differentiated hepatocellular carcinoma (HCC) to poorly differentiated HCC.We also characterized an undifferentiated HCC cell-line, referred to as ETK-1, which has the potency of bilateral differentiation, like liver stem cell, into both hepatocyte, referred to as MEK, and biliary epithelial cell, referred to as NEC.ETK-1 cell expressed neither HNF-1α nor HNF-4. MEK cell showed expression of both HNF-1α and HNF-4. NEC expressed only HNF-4, but not HNF-1α. ETK-1 and NEC had no expression of liver specific genes, such as transthyretin and albumin, AFP and so on, although MEK expressed all sets of liver specific genes. Our study focused on the mechanism how NEC has no expression of liver specific genes or HNF-1α in spite of its expression of HNF-4. Fluores … More cent microscopic observations of NEC cell demonstrated that the HNF-4 located in the cytoplasm, not in the nucleus. The lack of transference of HNF-4 from cytoplasm into nucleus seemed to induce its functional defect as a transcription regulator. Such abnormal distribution of nuclear transcription factors might be an important process in dedifferentiation of HCC.We also analysed the signal transduction molecules inplicated in liver enriched transcription regulation during dedifferentiation of HCC.Immunohistochemical and western- and northern-blot analysis of surgically hepatectomized HCC tissues showed that overexpression of SAP-1, a human transmembrane-type protein tyrosine phosphatase in well differentiated HCC and its expression decreased during dedifferentiation of HCC.Induction of overexpression of SAP-1 in poorly differentiated HCC cell-line by transgene caused redifferentiation of HCC, and suppressed cellular proliferation and invasion. SAP-1 may be a molecule implicated in evolution and metastasis of HCC through hepatocytic differentiation. Less