Anticancer Mechanisms Of Antimicrobial Peptide Temporin-1CEA On Human Breast Cancer SK-BR3Cells

Breast cancer is the most common malignancy in women. Recent studies have shownthat although breast cancer is often referred to as one disease, there are actually manydifferent types of breast cancer. Among them, HER-2overexpressing breast cancer cellshave become the focus of current research because of their high degree of malignancy andlow survival rate. Many therapeutic strategies have been developed for HER-2over-expressing breast cancer, including anti-HER2monoclonal antibodies. However, thetherapeutic efficacy of traditional therapeutics is still limit, and some patients appear to beresistant to anti-HER2antibodies treatment. Therefore, novel therapeutic strategies with novelmechanisms are urgently required.Because of the small molecular weight, high thermal stability and strong cationiccharacteristics, antimicrobial peptides have recently become a promising focus area inanticancer research. In this study, temporin-1CEa, one α-helical cationic peptide extractedfrom frog skin secretions, shows a potent anti-cancer activity against HER2-positive humanbreast cancer cell line SK-BR3. Using MTT test and LDH assay, the proliferating inhibitoryeffect of temporin-1CEa on SK-BR3cells were evaluated. The mode of cytotoxicity oftemporin-1CEa is detected by Annexin-V/PI double staining. The cellular targets fortemporin-1CEa were observed by scanning electron microscopy. Finally, the cell membranepotential, mitochondrial membrane potential, intracellular ROS level and free calcium ionsconcentrations were also determined.The results suggested that temporin-1CEa exerts cytotoxicity against SK-BR3cells in adose-dependent and a time-independent manner. By scanning electron microscopy, we foundthat temporin-1CEa treatment induced dramatic morphological changes in SK-BR3cells.Results of DiBAC4(3) and Rhodamine123staining showed that temporin-1CEa can flux intointracellular space of SK-BR3cells, leading to the increase of cell transmembrane potential,cell membrane depolarization and enhanced membrane permeability. Moreover, thecollapse of mitochondrial transmembrane potential, increased intracellular ROS level andelevated concentration of free calcium ions may suggest a mitochondrial damage anddysfunction.