RESUMO

Bioactive peptides have emerged as promising therapeutic agents with antimicrobial, antifungal, antiparasitic, and, recently, antitumoral properties with a mechanism of action based on membrane destabilization and cell death, often involving a conformational change in the peptide. This biophysical study aims to provide preliminary insights into the membrane-level antitumoral mode of action of crotalicidin, a cationic host defense peptide from rattlesnake venom, toward breast cancer cell lines. The lipid composition of breast cancer cell lines was obtained after lipid extraction and quantification to prepare representative cell membrane models. Membrane-peptide interaction studies were performed using differential scanning calorimetry and Fourier-transform infrared spectroscopy. The outcome evidences the potential antitumoral activity and selectivity of crotalicidin toward breast cancer cell lines and suggests a mechanism initiated by the electrostatic interaction of the peptide with the lipid bilayer surface and posterior conformation change with membrane intercalation between the acyl chains in negatively charged lipid systems. This research provides valuable information that clears up the antitumoral mode of action of crotalicidin.

Assuntos

Anti-Infecciosos , Neoplasias da Mama , Humanos , Feminino , Neoplasias da Mama/tratamento farmacológico , Fragmentos de Peptídeos/farmacologia , Bicamadas Lipídicas/química , Anti-Infecciosos/química , Peptídeos Catiônicos Antimicrobianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/química , Varredura Diferencial de Calorimetria

RESUMO

Breast cancer is the most common cancer that affects women globally and is among the leading cause of women's death. Triple-negative breast cancer is more difficult to treat because hormone therapy is not available for this subset of cancer. The well-established therapy against triple-negative breast cancer is mainly based on surgery, chemotherapy, and immunotherapy. Among the drugs used in the therapy are cisplatin and carboplatin. However, they cause severe toxicity to the kidneys and brain and cause nausea. Therefore, it is urgent to propose new chemotherapy techniques that provide new treatment options to patients affected by this disease. Nowadays, peptide drugs are emerging as a class of promising new anticancer agents due to their lytic nature and, apparently, a minor drug resistance compared to other conventional drugs (reviewed in Jafari et al., 2022). We have recently reported the cytotoxic effect of the antimicrobial peptide LyeTx I-b against glioblastoma cells (Abdel-Salam et al., 2019). In this research, we demonstrated the cytotoxic effect of the peptide LyeTx I-b, alone and combined with cisplatin, against triple-negative cell lines (MDA-MD-231). LyeTx-I-b showed a selectivity index 70-fold higher than cisplatin. The peptide:cisplatin combination (P:C) 1:1 presented a synergistic effect on the cell death and a selective index value 16 times greater than the cisplatin alone treatment. Therefore, an equi-effective reduction of cisplatin can be reached in the presence of LyeTx I-b. Cells treated with P:C combinations were arrested in the G2/M cell cycle phase and showed positive staining for acridine orange, which was inhibited by bafilomycin A1, indicating autophagic cell death (ACD) as a probable cell death mechanism. Furthermore, Western blot experiments indicated a decrease in P21 expression and AKT phosphorylation. The decrease in AKT phosphorylation is indicative of ACD. However, other studies are still necessary to better elucidate the pathways involved in the cell death mechanism induced by the peptide and the drug combinations. These findings confirmed that the peptide LyeTx I-b seems to be a good candidate for combined chemotherapy to treat breast cancer. In addition, in vivo studies are essential to validate the use of LyeTx I-b as a therapeutic drug candidate, alone and/or combined with cisplatin.