Selective death of human breast cancer cells by lytic immunoliposomes: Correlation with their HER2 expression level

Abstract 

Trastuzumab (Herceptin™) targets the human epidermal growth factor receptor 2 (HER2), which is overexpressed in 20–30% of breast and ovarian cancers carrying a bad prognosis. Our purpose was to target HER2-overexpressing human breast cancer cells with pegylated immunoliposomes bearing trastuzumab and containing melittin, which has recently shown anticancer properties. Using a panel of human breast cancer cells with different HER2 expression levels, these immunoliposomes decreased cancer cells viability in a dose–response manner and in correlation to their level of HER2 expression. Specific binding of the immunoliposomes to SKBr3 breast cancer cells was shown by ImageStream-based analysis. The morphological changes observed in the treated cells suggested a cytolytic process. This preclinical approach may suppose an effective strategy for the treatment of HER2-overexpressing tumors, and can support the development of an early phases I–II clinical trial. Trastuzumab resistant breast cancer cells (JIMT-1), can also be targeted using this approach.

Abbreviations: HER2/neu HER2, human epidermal growth factor receptor 2, AbDR, lytic immunoliposomes with trastuzumab™, Mab, monoclonal antibody, AMP, antimicrobial peptide, PLA₂, phospholipase 2, EYPC, egg yolk phosphatidylcholine, Chol, cholesterol, DSPE-PEG, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-PEG-2000, D2000M, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[maleimide (PEG 2000)], DR, lytic liposome (without antibody), Rhod, Lissamine rhodamine dye, Rhod-PE, lissamine rhodamine B 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine, THIS, histidine buffered solution, Rhod-AbDR, rhodamine labeled AbDR, Rhod-DR, rhodamine labeled DR, HPLC, high performance liquid chromatography, AbDR-ø, AbDR immunoliposome without lytic peptide, CC50, concentration corresponding to 50% cytotoxicity, PLD, phospholipase D, DAPI, 4′,6-diamidino-2-phenylindole dye

Keywords: Trastuzumab, Immunoliposomes, Melittin, Cell lysis, HER2, Anticancer therapy, Breast cancer cells