Anticancer activity of melittin-derived peptides bioconjugates

Conventional cancer treatments, while effective, are also associated with a variety of side effects that can lead to treatment resistance and increased disease recurrence. Therefore, there is a continuous search for therapeutic alternatives, such as anticancer peptides. Although promising, these molecules face challenges in terms of toxicity and selectivity. One solution is the use of aptamer peptides, molecules with high affinity for specific proteins overexpressed in tumor cells. The objective was to synthesize melittin, aptamer peptide (P7), and three bioconjugation strategies; identify the possible mechanism of action of these molecules; determine the expression of the glycoprotein CD44 in non-tumor and tumor cell lines; evaluate the hemolytic potential and cytotoxic activity of the bioconjugates in tumor and non-tumor cell lines. Peptides were synthesized by solid phase peptide synthesis and purified by high performance liquid chromatography. Bioconjugates were synthesized with the P7 peptide linked to the N-terminus or C-terminus of melittin and an aptamer linked to the N-terminus of melittin but separated by a spacer. The mechanism of action of the bioconjugates was evaluated using a membrane permeabilization assay, the expression of CD44 was determined using Western blotting assays, and the hemolytic potential was determined using a hemolytic activity assay. Toxicity in tumor and non-tumor cell lines was evaluated using MTT and colony formation assays. Results showed that melittin and the bioconjugates had a similar mechanism of action to the carpet model. In addition, bioconjugation proved to be more selective than melittin in cell viability assays, however, one of the strategies showed hemolytic activity. The Western blotting and colony formation assays are expected to demonstrate the overexpression of CD44 in tumor cell lines and the ability of the peptides to inhibit colony formation of the tested tumor cell lines, respectively. Thus, the partial results suggest that bioconjugation between aptamers emerges as a promising strategy for targeting molecules with anticancer potential.