title: Molecular mechanisms of antibacterial and antitumor actions of designed surfactant-like peptides.
abstract: Biomimicry of antimicrobial peptides secreted by innate immune systems represents a major strategy in developing novel antibacterial treatments. There are however emerging concerns over the possible compromise of host natural defenses by these biomimetic peptides due to their structural similarity. In our recent work we have extended the search by exploring the potential from unnatural synthetic antimicrobial peptides. Here we show that a series of surfactant-like peptides (A(m)K(n), m ≥ 3, n = 1, 2) can kill not only bacteria but also cancerous HeLa cells in similar manner. Under the same experimental conditions, however, these peptides showed little affinity to NIH 3T3 cells and human red blood cells (hRBCs), thus demonstrating high biocompatibility in selective responses to host mammalian cells and low hemolysis. A(9)K(1) was most effective in killing HeLa cells, a trend consistent with their bactericidal effects against Escherichia coli and Bacillus subtilis. Mechanistic investigations through combined studies of SEM and fluorescence assays revealed that the killing of bacteria and cancerous cells was caused by disrupting cell membranes, initiated by electrostatic interactions between cationic peptides and negatively charged cell membranes. In contrast, the absence of such interactions in the case of NIH 3T3 and hRBCs over the same peptide concentration range rendered low cytotoxicity. The most effective killing power of A(9)K(1) within this series benefited from the combined effects of several factors including modest micellar concentration and balanced amphiphilicity, consistent with its propensity of self-assembly and effective membrane lytic power.
authors: State Key Laboratory of Heavy Oil Processing and Centre for Bioengineering and Biotechnology, China University of Petroleum (East China), Qingdao, Shandong 266555, China.
authors: Cuixia
authors: C
authors: Chen
authors: Jing
authors: J
authors: Hu
authors: Shengzhong
authors: S
authors: Zhang
authors: Peng
authors: P
authors: Zhou
authors: Xichen
authors: X
authors: Zhao
authors: Hai
authors: H
authors: Xu
authors: Xiubo
authors: X
authors: Zhao
authors: Mohammed
authors: M
authors: Yaseen
authors: Jian R
authors: JR
authors: Lu
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis / Q000493:pharmacokinetics*; D016588:Anticarcinogenic Agents / Q000138:chemical synthesis / Q000493:pharmacokinetics*; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D001412:Bacillus subtilis / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects; D049109:Cell Proliferation; D004912:Erythrocytes / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects; D006367:HeLa Cells / Q000187:drug effects; D006461:Hemolysis; D006801:Humans; D051379:Mice; D008823:Micelles; D041681:NIH 3T3 Cells / Q000187:drug effects; D013329:Structure-Activity Relationship; D013501:Surface-Active Agents / Q000138:chemical synthesis / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D016588:Anticarcinogenic Agents; D023181:Antimicrobial Cationic Peptides; D008823:Micelles; D013501:Surface-Active Agents