Efficient expression of pro-urokinase by human lymphoblastoid Namalwa KJM-1 cells using Moloney retroviral promoter

摘要

We have compared the level of expression of several enhancer/promoters in human lymphoblastoid Namalwa KJM-1 cells when fused to a common reporter gene. A cassette containing the pro-urokinase (pro-UK) coding sequence followed by the rabbit β-globin and simian virus 40 (SV40) 3′ nontranslated region was used for evaluation of the enhancer activity. Cells containing Moloney murine leukemia virus (Mo-MuLV) promoter had an average of 10–20 fold higher expression levels of pro-UK than those containing other promoters, such as SV40 early gene promoter, human cytomegalovirus (hCMV) major immediate-early gene promoter, Rous sarcoma virus (RSV) promoter and chicken β-actin gene promoter. The expression level of pro-UK under the control of Mo-MuLV promoter was 2–3 μg/106 cells/day and was constant for more than 6 months. Furthermore, the production of a high producer clone, obtained by using dhfr gene coamplification, reached 30–40 μg/106 cells/day. Thus, Mo-MuLV promoter showed the desired characteristics for efficient expression of foreign genes in Namalwa KJM-1 cells.