Persistent expression of foreign genes in cultured hepatocytes: expressionvectors

We have optimized a liposome-based transfection method that mediated highly efficient stable expression of foreign genes in hepatocytes. Moreover, we have observed that the metallothionein 1 promoter in the bovine papilloma v irus-based expression vector drove the highest expression of foreign genes in hepatocytes as compared with the cytomegalovirus and the human polypepti de chain elongation factor 1 alpha (EF-1 alpha) promoters in the pcDNA 3-ba sed expression vector. The cytomegalovirus promoter failed to yield signifi cant expression in these cells. Furthermore, expression of foreign genes pe rsisted up to at least 15 passages when expression was under the control of either the EF-1 alpha or the metallothionein 1 promoter. Thus, these two p romoters led to comparable stability of foreign genes in hepatocytes, with the metallothionein 1 promoter yielding a higher level of expression of for eign genes in these cells. (C) 1999 Elsevier Science B.V. All rights reserv ed.