Construction of eukaryotic and prokaryotic expression vectors of interlukin-2/interferon β fusion gene regulated by carcinoembryonic antigen promotor

Objective To observe the expression of interlukin-2 (IL-2) and interferonβ (IFNBB) in colorectal tumor cell lines, the prokaryotic and eukaryotic IL-2/ IFNβ fusion gene vectors, which was up-regulated by carcinoembryonic antigen (CEA) promoter, were constructed. Methods cDNA and IFNβ cDNA were amplified by RT-PCR, and then fused into prokaryotic expression vector pGEX-5X-1 or eukaryotic expression vector pcDNA 3. 1/HisA or green fluorescent protein expression vector pEGFP-Cl. The fusion protein expression of the prokaryotic plasmid was identified by SDS -PAGE. Lovo ( high-express CEA), HT29 (low-express CEA) and Hela cells (none-express CEA) were transfected by fusion-gene-containing liposome. The apoptosis of these cells was detected by flow cytometry and flurescence microscopy, and the expression of the intracellular fusion protein by Western-blotting. Results E. coli expressing vector and tumor cell lines both could express IL-2/ IFNβ fusion gene. The fusion protein exerted significant killing effect on colorectal tumor cells. The fusion gene expression was higher in Lovo than in HT-29, and was almost undetectable in non-CEA expressing Hela cells, implying CEA promoter might up-regulate fusion gene expression. Conclusions CEA promoter specifically up-regulates IL-2/IFNβ fusion gene expression in tumor cell lines, and the production of the fusion protein may have anti-tumor effect.