Appl Microbiol Biotechnol, 2012 Nov 13
Tumor necrosis factor-related apoptosis-inducing ligand
(TRAIL), as an anticancer protein with tumor-selective apoptotic activity, has
been examined for use in clinical application. Melittin, an antibacterial
peptide isolated from the bee Apis mellifera, has shown strong cytotoxicity to
both tumor and normal cells. To ameliorate the cytotoxicity of melittin on
cells and enhance the activity of TRAIL on cancer cells, we constructed a novel
fusion protein, sTRAIL-melittin, containing a small ubiquitin-related modifier
(SUMO) tag and expressed this fusion protein in Escherichia coli. Data showed
that expression of the soluble fusion protein with the SUMO tag was
approximately 85 % of total target protein which was much higher than that
without the SUMO tag (approximately 10 %); sTRAIL-melittin was easily purified
using Ni-NTA affinity chromatography and the tag was removed easily using SUMO-specific
protease. To assay anticancer activity and side effects, methyl thiazolyl
tetrazolium, hemolytic, and apoptosis assays were employed. Results
demonstrated that sTRAIL-melittin had cytotoxic and apoptotic activity in K562
leukemia cells and HepG2 liver carcinoma cells, while it had only a minimal
effect on erythrocytes and normal HEK293 cells. This indicates that the
cytotoxicity of sTRAIL-melittin in normal cells was low and the anticancer
activity of the fusion protein in tumor cells was significantly enhanced
compared with sTRAIL (P < 0.01). Furthermore, we found that sTRAIL-melittin
also showed antibacterial activity to Staphylococcus aureus due to the presence
of the melittin domain. Therefore, TRAIL fused with an antibacterial peptide may
be a promising novel TRAIL-based anticancer treatment strategy.
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