Specific antibody-receptor interactions trigger InlAB-independent uptake of Listeria monocytogenes into tumor cell lines.
Bottom Line: Here, we describe the construction of a novel, internalin A and B (InlAB)-deficient Listeria monocytogenes strain (Lm-spa+), which expresses protein A of Staphylococcus aureus (SPA) and anchors SPA in the correct orientation on the bacterial cell surface.Binding of Trastuzumab (Herceptin®) or Cetuximab (Erbitux®) to Lm-spa+, two clinically approved monoclonal antibodies directed against HER2/neu and EGFR/HER1, respectively, triggers InlAB-independent internalization into non-phagocytic cancer cell lines overexpressing the respective receptors.Binding of receptor-specific antibodies to SPA-expressing L. monocytogenes may represent a promising approach to target L. monocytogenes to host cells expressing specific receptors triggering internalization.
Affiliation: Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), Universität Würzburg, Versbacher Strasse 8, Würzburg, 97078, Deutschland. firstname.lastname@example.orgShow MeSH
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Mentions: Expression of SPA by the constructed Lm strains was analyzed by Western blotting using polyclonal protein A antibody. Bacterial cell surface and cytoplasmic protein fractions were examined after growth of Lm-spa+ in BHI containing 1% amberlite XAD-4. Addition of XAD-4 to the culture medium enhances the activity of the virulence gene activator PrfA and hence leads to an enhanced transcription of the spa gene which is under the control of the PrfA-dependent hly promoter . SPA was readily detected in the cell surface protein fraction of Lm-spa+ and to a lower extent in the internal protein extract fraction. (Figure 1A). As expected, no SPA was present in the parental strain ΔtrpS,aroA,inlA/B × pFlo-trpS, termed Lm-spa- (Figure 1A).
Affiliation: Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), Universität Würzburg, Versbacher Strasse 8, Würzburg, 97078, Deutschland. email@example.com