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Heisig, Martin; Frentzen, Alexa; Bergmann, Birgit; Galmbacher, Katharina; Gentschev, Ivaylo; Hotz, Christian; Schoen, Christoph; Stritzker, Jochen; Fensterle, Joachim; Rapp, Ulf R.; Goebel, Werner (2011): Specific antibody-receptor interactions trigger InlAB-independent uptake of listeria monocytogenes into tumor cell lines. In: BMC Microbiology 11:163


Background: Specific cell targeting is an important, yet unsolved problem in bacteria-based therapeutic applications, like tumor or gene therapy. 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. Results: This listerial strain efficiently binds antibodies allowing specific interaction of the bacterium with the target recognized by the antibody. Binding of Trastuzumab (Herceptin (R)) or Cetuximab (Erbitux (R)) 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. Internalization, subsequent escape into the host cell cytosol and intracellular replication of these bacteria are as efficient as of the corresponding InlAB-positive, SPA-negative parental strain. This specific antibody/receptor-mediated internalization of Lm-spa(+) is shown in the murine 4T1 tumor cell line, the isogenic 4T1-HER2 cell line as well as the human cancer cell lines SK-BR-3 and SK-OV-3. Importantly, this targeting approach is applicable in a xenograft mouse tumor model after crosslinking the antibody to SPA on the listerial cell surface. Conclusions: 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.