Fig. 4.
In vitro targeting studies using HBc particles. (A) Fluorescence intensity histogram of cells treated with WT-HBc particles. (B) Fold increase in median fluorescence intensity, relative to naïve cells, of cells treated with fluorescently labelled Alexa Fluor™ 488 WT-HBc, ΔHBc or ZHER2-ΔHBc particles at increasing concentrations of 10, 20 or 40 μg/mL. Flow cytometry confirmed the non-specific uptake of WT-HBc particles by cancer cell lines in a time- and dose-dependent manner. ΔHBc particles showed a significant reduction in uptake, supporting the hypothesis that the deletion of the arginine-rich domain can reduce the non-specific binding ability of wild type HBc particles. Specific uptake of ZHER2-ΔHBc particles in HER2 (+) and (+++) cells is occurred in a time-, dose- and HER2-dependent manner. Values are expressed as fold increase ±SD. *P < 0.05, **P < 0.01, ***P < 0.001, relative to MDA-MB-468 cell line (one-way ANOVA test).