title: Cytoplasmic delivery of liposomes into MCF-7 breast cancer cells mediated by cell-specific phage fusion coat protein.
abstract: Earlier, we have shown that doxorubicin-loaded liposomes (Doxil) modified with a chimeric phage fusion coat protein specific toward MCF-7 breast cancer cells identified from a phage landscape library demonstrated a significantly enhanced association with target cells and an increased cytotoxicity. Based on some structural similarities between the N-terminus of the phage potein and known fusogenic peptides, we hypothesized that, in addition to the specific targeting, the phage protein may possess endosome-escaping potential and an increased cytotoxicity of drug-loaded phage protein-targeted liposomes may be explained by an advantageous combination of both, cell targeting and endosomal escape of drug-loaded nanocarrier. The use of the fluorescence resonance energy transfer (FRET) technique allowed us to clearly demonstrate the pH-dependent membrane fusion activity of the phage protein. Endosomal escape and cytosolic delivery of phage-liposomes was visualized with fluorescence microscopy. Endosome acidification inhibition by bafilomycin A 1 resulted in decreased cytotoxicity of the phage-Doxil, while the endosome disruption by chloroquine had a negligible effect on efficacy of phage-Doxil, confirming its endosomal escape. Our results demonstrated an endosome-escaping property of the phage protein and provided an insight on mechanism of the enhanced cytotoxicity of phage-Doxil.
authors.affiliation: Center for Pharmaceutical Biotechnology and Nanomedicine, Northeastern University, Boston, Massachusetts 02115, USA.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.forename: Shenghong
authors.initials: S
authors.lastname: Yang
authors.forename: Valery A
authors.initials: VA
authors.lastname: Petrenko
authors.forename: Vladimir P
authors.initials: VP
authors.lastname: Torchilin
mesh_terms: D001943:Breast Neoplasms / Q000188:drug therapy; D036022:Capsid Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D004317:Doxorubicin / Q000008:administration & dosage / Q000737:chemistry*; D016503:Drug Delivery Systems / Q000379:methods*; D011992:Endosomes / Q000378:metabolism*; D005260:Female; D006801:Humans; D008081:Liposomes / Q000008:administration & dosage / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D014760:Viral Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D036022:Capsid Proteins; D008081:Liposomes; D014760:Viral Fusion Proteins; D004317:Doxorubicin