In Silico and in Vitro Studies of Cytotoxic Activity of Different Peptides Derived from Human Lactoferrin Protein

Antimicrobial peptides belong to a large family of bioactive peptides that play an important role in human health. Lactoferrin of transferrin family is considered to be a glycoprotein. Human lactoferrin has a length of 689 - 711 amino acid polypeptides. Lactoferrin plays a role in various biological activities such as anticancer, antibacterial, antiviral, antifungal, and anti-inflammatory activity, and also as an immune system regulator.
In this study, we examined the toxic effects of human lactoferrin-derived peptides on breast cancer cells in vitro using the web server Anticp. The results obtained from the Anticp web server showed that four peptides (P39, P40, P24, P66), out of the 70 peptides, had anticancer activity, and 66 peptides had non-anticancer activity.
The cytotoxicity of two peptides with high cytotoxic activity (P39, P40) and a peptide with low cytotoxic activity (P38) on breast cancer cells (MCF-7, MDA-MB-231) was examined using the MTT assay. The CC50 values of the peptides (P39, P40) were 100 μg/mL for MCF-7 cells and 950 and 1000 μg/mL for MDA-MB-231 cells, respectively.
The results showed that the activity of the cytotoxic peptides P39 and P40 was significantly higher than that of P38 on the breast cancer cells (P ≤ 0.001). Cancer cells treated with CC50 concentrations showed a percentage of the cells detached from the flask and surrounding cells as well as shrinkage and deformation on the surface. Also, apoptotic seeds inside the cells were observed with 40X magnification.
These finding demonstrated that P39 and P40 peptides could be appropriate candidates for in vivo testing as cytotoxic agents.