Human lactoferricin derived di-peptides deploying loop structures induce apoptosis specifically in cancer cells through targeting membranous phosphatidylserine

Abstract

Host defense-derived peptides have emerged as a novel strategy for the development of alternative anticancer therapies. In this study we report on characteristic features of human lactoferricin (hLFcin) derivatives which facilitate specific killing of cancer cells of melanoma, glioblastoma and rhabdomyosarcoma compared with non-specific derivatives and the synthetic peptide RW-AH. Changes in amino acid sequence of hLFcin providing 9-11 amino acids stretched derivatives LF11-316, -318 and -322 only yielded low antitumor activity. However, the addition of the repeat (di-peptide) and the retro-repeat (di-retro-peptide) sequences highly improved cancer cell toxicity up to 100% at 20 μM peptide concentration. Compared to the complete parent sequence hLFcin the derivatives showed toxicity on the melanoma cell line A375 increased by 10-fold and on the glioblastoma cell line U-87mg by 2-3-fold. Reduced killing velocity, apoptotic blebbing, activation of caspase 3/7 and formation of apoptotic DNA fragments proved that the active and cancer selective peptides, e.g. R-DIM-P-LF11-322, trigger apoptosis, whereas highly active, though non-selective peptides, such as DIM-LF11-318 and RW-AH seem to kill rapidly via necrosis inducing membrane lyses. Structural studies revealed specific toxicity on cancer cells by peptide derivatives with loop structures, whereas non-specific peptides comprised α-helical structures without loop. Model studies with the cancer membrane mimic phosphatidylserine (PS) gave strong evidence that PS only exposed by cancer cells is an important target for specific hLFcin derivatives. Other negatively charged membrane exposed molecules as sialic acid, heparan and chondroitin sulfate were shown to have minor impact on peptide activity.

Anticancer activities of bovine and human lactoferricin-derived peptides

“…Gly-Gly linker has previously been used in other CPP-AMP chimeras as described above (Hilchie et al 2013, Lemeshko 2013, while a Pro linker has been used by other research groups to create other dimer or retro-dimer peptides with improved cancer cell toxicity (Riedl et al 2015). In the presence of both hLF11-LFcinB1 chimeras, Jurkat cell killing was substantially increased compared to either component peptide alone (Fig.…”

Lactoferrin’s Anti-Cancer Properties: Safety, Selectivity, and Wide Range of Action

“…Interestingly, N-terminal region of bLf, which shows a different consensus sequence (A 1 PRKN 5 ), is able to interact with cell membrane-associated GAGs similarly to hLf [125]. Moreover, Riedl and colleagues have shown that phosphatidylserine, a cytoplasmic membrane component largely represented on tumor cells, is a crucial target for the specific anti-cancer activity of human Lfcin (Lfcin-H) derivatives [126]. This primary selective interaction via cell surface receptors can explain the most archaic function ascribed to Lf, i.e., its cytotoxic activity.…”

Anticancer potential of bioactive peptides from animal sources

“…Specifically, peptides target negatively charged membrane components in the membrane, such as phosphatidylserine (PS), sialic acid or heparan sulfate. In fact, the exposure of the negatively charged lipid PS on the outer leaflet of the cancer cell membrane is a key difference between cancerous and non-cancerous cells, which are overall neutrally charged, owing to zwitterionic phosphatidylcholine and sphingomyelin (166,167).…”