Regulation of albumin and alpha-fetoprotein gene expression

白蛋白和甲胎蛋白（AFP）基因串联排列在人类4号染色体上。然而，这两种基因的调节在出生后是相互的。事实上，AFP基因表达在出生后降低到几乎检测不到的水平;相反，白蛋白基因表达在整个生命中保持高水平。AFP基因在人肝癌细胞中重新表达，本研究采用北方印迹法和CAT质粒转染法分析胶体渗透压（COP）、肝细胞生长因子（HGF）和丁酸盐对AFP基因和白蛋白基因表达的调控。COP通过抑制它们的启动子活性来下调这两个基因。丁酸盐是正常结肠植物群的天然发酵产物，能抑制人肝癌细胞的生长。丁酸通过调节促孔剂活性上调白蛋白基因表达，而下调AFP基因表达。因此，丁酸可能通过门脉血流在人肝癌细胞中起分化诱导剂的作用。

Albumin and Alpha-fetoprotein (AFP) genes are tandemly arranged on human chromosome 4. However, the regulation of both genes is reciprocal after birth. In fact, AFP gene expression decreases to an almost undetectable level after birth ; in contrast, albumin gene expression remains high throughout life. The AFP gene is re-expressed in human hepatoma cells.In this study, the regulation of albumin and AFP genes by colloid osmotic pressure (COP), hepatocyte growth factor (HGF) and butyrate was analyzed using Northern blotting and CAT plasmid transfection assay. COP down-regulated both genes through the suppression of their promoter activities. HGF also repressed the AFP promoter activity, resulting in reduction of AFP mRNA level in a dose-dependent manner.Butyrate, a natural fermentation product of nomal colonic flora, inhibited cell growth in human hepatoma cells. Butyrate up-regulated the albumin gene expression, whereas it down-regulated the AFP gene expression through the modulation of their poromoter activities. Thus, it is possible that butyrate acts as a differentiation-inducer via the portal blood flow in human hepatoma cells.