magainin-2-peptide--xenopus and Neoplasms

Cancer treatment by conventional chemotherapy is hindered by toxic side effects and the frequent development of multi-drug resistance by cancer cells. Cationic antimicrobial peptides (CAPs) are a promising new class of natural-source drugs that may avoid the shortcomings of conventional chemotherapy because certain CAPs exhibit selective cytotoxicity against a broad spectrum of human cancer cells, including neoplastic cells that have acquired a multi-drug-resistant phenotype. Tumour cell killing by CAPs is usually by a cell membrane-lytic effect, although some CAPs can trigger apoptosis in cancer cells via mitochondrial membrane disruption. Furthermore, certain CAPs are potent inhibitors of blood vessel development (angiogenesis) that is associated with tumour progression. This article reviews the mechanisms by which CAPs exert anticancer activity and discusses the potential application of selected CAPs as therapeutic agents for the treatment of human cancers.

Topics: Amino Acid Sequence; Animals; Antimicrobial Cationic Peptides; Antineoplastic Agents; Apoptosis; Cell Membrane; Cell Survival; Defensins; Drug Carriers; Drug Design; Humans; Lactoferrin; Magainins; Mitochondrial Membranes; Molecular Sequence Data; Neoplasms; Protein Structure, Secondary; Proteins; Xenopus Proteins

Cationic antimicrobial peptides (CAPs) with antitumor activity have potential for use as novel antitumor agents because of their lower risk for induction of resistance. Of these peptides, magainin II (MG2) exhibited cytotoxicity in tumor cells only at high concentrations, likely due to the inefficiency of MG2 in cell membrane binding and cell entry. Conjugation to a cell-penetrating peptide (CPP) might enhance the cytotoxicity of MG2 in tumor cells. Here, we constructed a fusion peptide MG2A by conjugating MG2 to the N-terminus of the CPP penetratin (Antp). It was found that the fusion peptide MG2A is more potent than unconjugated MG2 at tumor cell killing. The IC50s of MG2A for the tumor cells tested were at least 30 times lower than the IC50s of unconjugated MG2. These data indicate that conjugation to Antp significantly enhanced the cytotoxicity of MG2 in tumor cells. Moreover, the IC50s of MG2A for tumor cells are within 2 to 3 μM, which are about three to five times lower than the IC50 for normal cells. Furthermore, chondroitin sulfate (CS) was found to be overexpressed on the surface of the tested tumor cells, and the cytotoxicity of MG2A could be inhibited by the addition of exogenous CS. These results suggest that binding of Antp to CS on tumor cells might be one important cause for the selective cytotoxicity of MG2A in tumor cells. Taken together, conjugation of MG2 to Antp can significantly enhance its antitumor activity, and the fusion of CAP to Antp might be an alternative for cancer-targeted therapy.

Topics: Animals; Antineoplastic Agents; Apoptosis; Carcinoma, Non-Small-Cell Lung; Carrier Proteins; Caspases; Cell Survival; Cell-Penetrating Peptides; Central Nervous System Neoplasms; Chlorocebus aethiops; Chondroitin Sulfates; Drug Carriers; Glioma; HeLa Cells; Humans; Inhibitory Concentration 50; Kidney Tubules, Proximal; Lung Neoplasms; Magainins; Melanoma; Molecular Targeted Therapy; Neoplasms; Rats; Skin Neoplasms; Vero Cells; Xenopus Proteins