Construction of Two AFP-positive Hepatoma Cell-specific Gene Regulatory Sequences

Two chimerical regulation sequences for gene expression, one (called ATrPS) harboring an enhancer of human alpha1-antitrypsin gene (AT) and a promoter and silencer(rPS)of rat afp gene, and another (called rAFP) consisting of enhancer III of rat afp gene and its rPS, were constructed, respectively. Then, two CAT expression vectors, rAFP-pCAT and ATrPS-pCAT, were constructed in which the cat reporter gene was put under the control of these elements, respectively. CAT activities could were detected in the AFP positive liver cancer cells and also in those liver cancer cells, liver cells or non-liver cells whose AFP were negative. Results showed that for both constructs, the CAT activities could be found in all AFP positive hepatoma cells, however, while this activity can not be detected in all AFP negative cells. Similar results were observed in primary cell cultures. The results showed that our regulation elements of gene expression really possessed cell-type specificity for AFP positive cells. The cell-type specificity remains when the length of rAFP was cut short as to 0.67 kb; and the activity seemed higher. These regulatory sequences of gene expression may be used in gene therapy for primary liver cancer.