Bacterial outer membrane vesicles (OMVs) have recently drawn a
great deal of attention due to their therapeutic efficiency and ability
to target specific cells. In the present study, we sought to probe
engineered OMVs as novel and promising carriers to target breast cancer
cells. Following the fusion of the affiEGFR-GALA structure to the C-terminal of ClyA as an anchor protein, the ClyA-affiEGFR-GALA construct was successfully expressed on the surface of ∆msbB/∆pagP E. coli
W3110-derived OMVs. Morphological features of the engineered and
wild-type OMVs were identical. The engineered OMVs induced no
endotoxicity, cytotoxicity, or immunogenicity, indicating the safety of
their application. These OMVs could specifically bind to EGF receptors
of MDA-MB-468 cells expressing high levels of EGFR and not to those with
low levels of EGFR (HEK293T cells). Interestingly, despite a lower
binding affinity of the engineered OMVs relative to the positive control
Cetuximab, it was strong enough to identify these cells. Moreover,
confocal microscopy revealed no uptake of the modified OMVs by the
EGFR-overexpressing cells in the presence of EGFR competitors. These
results suggest that OMVs might internalize into the cells with EGF
receptors, as no OMVs entered the cells with any EGFR expression or
those pretreated with EGF or Cetuximab. Regarding the EGFR-binding
affinity of the engineered OMVs and their cellular uptake, they are
presented here as a potential carrier for cell-specific drug delivery to
treat a wide variety of cancer cells. Interestingly, the engineered
OMVs are capable of reaching the cytoplasm while escaping the endosome
due to the incorporation of a fusogenic GALA peptide in the construct.