Structural Analysis of the 5'-Flanking Region of Human Alpha-Fetoprotein Encoding Gene

Abstract

Alpha fetoprotein (AFP) is a growth factor and a signaling molecule that promotes the development of HCC. However, the mechanism of the awakening of AFP in course of HCC progression remains unclear. We have studied the structure of AFP 5'-flanking regulatory sequence using dual-luciferase reporter vectors with fragments of this region. Reporter constructs were transfected into HepG2 and PLC hepatoma cell lines. The AFP 5'-flanking regulatory sequence between -1871 and -1004 bp was promoting gene transcription, while the effects of the sequence between -1004 and -667 bp were small. The fragment located between positions -667 and -448 bp inhibited the transcriptional activity of the AFP gene, while the fragment located between -448 and -287 bp promoted expression of AFP. The effects of the adjacent promoter sequence were small. A variety of transcription factor binding sites were mapped.