The aim of this study was to develop effective and specific anti-
cancer drugs based on membrane active
peptides. In previous studies we showed that human
lactoferricin (hLFcin) derived
peptides facilitate specific killing of
cancer cells. These antitumor
peptides were found by conventional
melanoma two-dimensional (2D) cell cultures to induce apoptosis of
cancer cells and to specifically target
lipid phosphatidylserine located on the outside of
cancer cell membranes. In order to have a more relevant in vitro model able to mimic the natural microenvironments of
tumor tissues we established three-dimensional (3D) multicellular
tumor spheroids (MCTS). We used a set of (retro) di-
peptides derived from LF11, an 11
amino acid long fragment of hLFcin, which differed in
peptide length, positive net charge and hydrophobicity and determined antitumor activity and non-specific toxicity on non-neoplastic cells using 2D and 3D model systems. 2D studies unveiled a correlation between length, positive net charge and hydrophobicity of
peptides and their specific antitumor activity. (Retro) di-
peptides as R-DIM-P-LF11-215 and DIM-LF11-322 with a net charge of +9 and moderate hydrophobicity exhibited the highest specific antitumor activity. Further evaluation of the
peptides anticancer activity by 3D in vitro studies confirmed their higher activity and
cancer specificity compared to their parent R-DIM-P-LF11, with the exception of DIM-LF11-339. This highly hydrophobic
peptide caused cell death mainly at the border of
tumor spheroids indicating that too high hydrophobicity may prevent
peptides from reaching the center of the spheroids.