Cell specificity and molecular mechanism of antibacterial and antitumor activities of carboxyl-terminal RWL-tagged antimicrobial peptides

Abstract

Antimicrobial peptides (AMPs) constitute a diverse class of naturally occurring or synthetic antimicrobial molecules that have potential for use in the treatment of drug-resistant infections. Several undesirable properties of AMPs, however, may ultimately hinder their development as antimicrobial agents. Thus, new synthetic strategies, including primarily the de novo design of AMPs, urgently need to be developed. In this study, a series of peptides, H-(RWL) n (n = 1, 2, 3, 4, or 5), were designed. H represents GLRPKYS from the C-terminal sequence of AvBD-4. Our results showed that these RWL-tagged peptides can kill not only bacteria but also human hepatocellular carcinoma HepG2 cells. However, the peptide tagged with two repeats of RWL (GW13) showed less affinity to human embryonic lung fibroblast MRC-5 cells or human red blood cells (hRBCs) than HepG2 cells. These results demonstrated that GW13, with high amphiphilicity, exerted great selectivity toward bacteria and cancer cells, sparing host mammalian cells. The mechanism of action against bacteria was elucidated through combined studies of scanning electron microscopy (SEM) and fluorescence assays, showing that the peptide possessed membrane-lytic activities against microbial cells. The fluorescence assays illustrated that GW13 induced apoptosis in HepG2 cells. The cell morphology of HepG2 cells, observed by SEM, further illustrated that GW13 causes cell death by damaging the cell membrane. Our results indicate that GW13 has considerable potential for future development as an antimicrobial and antitumor agent.

Antimicrobial peptides: Promising alternatives in the post feeding antibiotic era

“…Following the initial attachment, peptides insert into the bacterial membrane to form transmembrane pores (membrane permeabilization and lysis) . There are several widely accepted models accounting for the antimicrobial mechanism of AMPs, including the barrel‐stave model, carpet model and toroidal model .…”

Application Value of Antimicrobial Peptides in Gastrointestinal Tumors

“…Peptides with higher RWL content were richer in their α-helical structure. Compared with peptides GW10 and GW13, peptides with an α-helical conformation (GW16, GW19, and GW22) showed higher cytotoxicity on human hepatocellular carcinoma HepG2 cells [91]. This finding suggests that the abundant α-helical structure may be responsible for the gradual increase in cytotoxicity.…”