OBJECTIVETo generate a recombinant expression system of repeated serial antibiotic peptide Alloferon-1 DNA segment with trypsin digestion site and to determine its anti-tumor activity in vitro.

METHODSA 14 repeated serial DNA segment of Alloferon-1 with a lysine residual at the C-end that acts as the trypsin digestion site was constructed. pET42a vector and E.coli BL21DE3 were applied to generate the prokaryotic expression system of the repeated serial DNA segment of Alloferon-1. The yield of target recombinant product was measured by SDS-PAGE and Bio-Rad Gel image system. Ni-NTA affinity column, trypsin digestion and Sephadex G-50 column were used to purify 14 rAlloferon-1-K fusion protein and rAlloferon-1-K monomer. By using the co-cultivation of BALB/c mouse splenocyte with K562, KB or SGC tumor cells and CCK-8 detection method, the effects of rAlloferon-1-K, chemosynthetic Alloferon-1 (cAlloferon-1) and Alloferon-1-K (cAlloferon-1-K) on the growth and proliferation of tumor cells were detected.

RESULTSThe prokaryotic expression system E.coli BL21DE3pET42a-14 Alloferon-1-K efficiently expressed 14 rAlloferon-1-K fusion protein under inducement of IPTG,and the yield of fusion protein was approximate 30% of the total bacterial proteins. 0.1≊10 ng/ml rAlloferon-1-K remarkably increased the effect of mouse splenocytes to inhibit the growth and proliferation of K562, KB and SGC cells (P<0.05), and there was no statistically significant difference of the anti-tumor ability of rAlloferon-1-K compared to that of cAlloferon-1 or cAlloferon-1-K (P>0.05).

CONCLUSIONA prokaryotic expression system of repeated serial Alloferon-1 DNA segment has been successfully constructed with high yield of rAlloferon-1-K, which maintains anti-tumor activity in vitro.