title: Apoptotic epidermal growth factor (EGF)-conjugated block copolymer micelles as a nanotechnology platform for targeted combination therapy.
abstract: The overexpression of epidermal growth factor receptor (EGFR) in human epithelial cancers has been associated with aggressive disease, poor patient prognosis, and a high incidence of metastases. In the present study, block copolymer micelles are conjugated with epidermal growth factor (EGF), which acts as both a targeting ligand for the drug carrier and an apoptotic factor against EGFR-overexpressing cancers. Drug-free EGF-conjugated micelles are shown to result in cell-cycle arrest at the G 1 phase and subsequent induction of cell-type-specific apoptosis in EGFR-overexpressing breast cancer cells as demonstrated by flow cytometric analysis. EGF delivered as EGF-conjugated micelles was found to be 13-fold more potent than free EGF; the IC 50 was decreased from 0.98 +/- 0.1 nM for free EGF to 0.076 +/- 0.01 nM for EGF micelles. The apoptotic micelles, however, are non-antiproliferative to cells expressing a low level of EGFR, suggesting that the apoptotic micelles have minimal or no toxicity against normal healthy tissues. Ellipticine, a chemotherapeutic agent, was loaded into the EGF-micelles after it had been shown, using the combination index-isobologram equation, to act synergistically with EGF. A 10-fold increase in EGF content in the ellipticine-loaded micelles lowered the IC 50 of ellipticine in EGFR-overexpressing breast cancer cells by more than 18-fold. The EGF-micelles have the potential to be further pursued as a versatile nanotechnology platform for targeted delivery of a wide range of chemotherapeutic agents as a combination therapy for the treatment of EGFR-overexpressing cancers.
authors.affiliation: Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, Division of Nuclear Medicine, University Health Network, University of Toronto, 144 College Street, Toronto, Ontario, Canada.
authors.forename: Helen
authors.initials: H
authors.lastname: Lee
authors.forename: Meiduo
authors.initials: M
authors.lastname: Hu
authors.forename: Raymond M
authors.initials: RM
authors.lastname: Reilly
authors.forename: Christine
authors.initials: C
authors.lastname: Allen
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D004815:Epidermal Growth Factor / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D008823:Micelles; D036103:Nanotechnology; D011108:Polymers / Q000737:chemistry*
chemical_list: D008823:Micelles; D011108:Polymers; D004815:Epidermal Growth Factor