Cost-effective production of recombinant human interleukin 24 by lactose induction and a two-step denaturing and one-step refolding method.

Recombinant human interleukin 24 (rhIL24) is a member of the interleukin 10 (IL10) family of cytokines with novel therapeutic properties. Human IL24 possesses three N glycosylation sites and a disulfide bridge. The cost and composition of culture media is critical for commercial-scale production of recombinant proteins in E. coli. Addition of yeast extract and glucose to medium enhances rhIL24 production, and the use of lactose instead of IPTG for induction drops the cost and decreases toxicity. In addition, a two-step denaturing and one-step refolding (2DR) strategy improves rhIL24 production. The 2DR strategy replaces a more conventional approach for protein solubilization and refolding. LC-MS/MS provides definitive identification and quantitative information on rhIL24. Single-step purified rhIL24 displayed biological activity on HepG2 hepatocellular carcinoma cells, but no effect on L02 cells. Proliferation analysis suggests that rhIL24 may have potential use as a medication. In the present study, we developed a simple process for producing quality product with high purity. The expression and purification of rhIL24 described here may be a step towards inexpensive large-scale production.