Development and characterization of Melittin-IL-24 fusion protein with synergistically enhanced anti-tumor activity

Introduction: Targeted cancer therapy using recombinant fusion proteins offers a novel and precise approach to addressing limitations associated with conventional treatments, such as nonspecific toxicity and drug resistance. Fusion proteins are designed to synergistically incorporate multiple protein domains, thereby enhancing bioactivity and creating novel functional combinations with broad applications. In this study, we report the innovative design and evaluation of a fusion protein that combines interleukin-24 (IL-24), a tumor-suppressive cytokine, with melittin, a potent cell-lytic peptide derived from honey-bee venom. Methods: This combination synergistically unites the pro-apoptotic properties of IL-24 with the membrane-disrupting activity of melittin to increase cytotoxicity against cancer cells. The Melittin-IL-24 construct was expressed in Escherichia coli BL21(DE3) and induced with IPTG. Results: After affinity chromatography, we obtained ~100 mg of > 97 %-pure fusion protein per liter of culture, as verified by SDS-PAGE, Western blotting, and HPLC. MTT assays showed significant cytotoxicity of Melittin-IL-24 toward MCF-7 breast-cancer cells (IC₅₀ = 52 µg/mL), whereas IL-24 alone exhibited an IC₅₀ of 66 µg/mL. Both proteins were far less toxic to normal MCF-10F mammary epithelial cells. Conclusion: By combining the apoptotic effects of IL-24 with the cell-lytic properties of melittin, Melittin-IL-24 demonstrates enhanced therapeutic potential and may represent a promising strategy for targeted cancer therapy.