GENE-TRANSFER INTO HEPATOMA-CELL LINES VIA THE SERPIN ENZYME COMPLEX RECEPTOR

The serpin enzyme complex receptor (SECR) expressed on hepatocytes bin ds to a conserved sequence in alpha(1)-antitrypsin (alpha(1)-AT) and o ther serpins. A molecular conjugate consisting of a synthetic peptide (C1315) based on the SECR binding motif of human alpha(1)-AT covalentl y coupled to poly-L-lysine was used to introduce reporter genes into h epatoma cell lines in culture. This conjugate condensed DNA into spher oidal particles 18-25 nm in diameter. When transfected with the SECR-d irected complex containing pGL3, Hep G2 cells that express the recepto r, but not Hep G2 cells that do not, expressed a peak luciferase activ ity of 538,731 +/- 144,346 integrated light units/mg protein 4 days af ter transfection. Free peptide inhibited uptake and expression in a do se-dependent manner. Complexes of DNA condensed with polylysine or ini midyl-3-(2-pyridyldithio)propionate-substituted polylysine were ineffe ctive. Transfection with a plasmid encoding human factor IX produced e xpression in Hep G2 (high) and HuH7 cells that express SECR but not He p G2 (low) cells that lack the receptor. Fluorescein-labeled C1315 pep tide labeled 9-31% of Hep G2 (high), 10-14% of HuH7, and 0.6-3.4% of H ep G2 (low) cells, and when the lac Z gene was transfected, only these cells expressed beta-galactosidase. SECR-mediated gene transfer gives efficient, specific uptake and high-level expression of three reporte r genes, and the system merits further study for gene therapy.