Targeted delivery of an ADP-ribosylating bacterial toxin into cancer cells

Abstract

The actin cytoskeleton is an attractive target for bacterial toxins. The ADP-ribosyltransferase TccC3 from the insect bacterial pathogen Photorhabdus luminescence modifies actin to force its aggregation. We intended to transport the catalytic part of this toxin preferentially into cancer cells using a toxin transporter (Protective antigen, PA) which was redirected to Epidermal Growth Factor Receptors (EGFR) or to human EGF receptors 2 (HER2), which are overexpressed in several cancer cells. Protective antigen of anthrax toxin forms a pore through which the two catalytic parts (lethal factor and edema factor) or other proteins can be transported into mammalian cells. Here, we used PA as a double mutant (N682A, D683A; mPA) which cannot bind to the two natural anthrax receptors. Each mutated monomer is fused either to EGF or to an affibody directed against the human EGF receptor 2 (HER2). We established a cellular model system composed of two cell lines representing HER2 overexpressing esophageal adenocarcinomas (EACs) and EGFR overexpressing esophageal squamous cell carcinomas (ESCCs). We studied the specificity and efficiency of the re-directed anthrax pore for transport of TccC3 toxin and established Photorhabdus luminescence TccC3 as a toxin suitable for the development of a targeted toxin selectively killing cancer cells.

Targeted Delivery of 111In Into the Nuclei of EGFR Overexpressing Cells via Modular Nanotransporters With Anti-EGFR Affibody

“…EGFRs are highly convenient for the targeted delivery of various drugs into cancer cells. A number of drug delivery vehicles were produced for this purpose and evaluated in vitro and in vivo [ (Chen et al, 2002;Lu et al, 2005;Liu et al, 2010;Song et al, 2016;Slastnikova et al, 2017b;Zahaf et al, 2017;Rosenkranz et al, 2018), etc.]. The main areas of EGFR-targeted drug therapy include: (1) development of drugs based on anti-EGFR antibodies binding to the extracellular EGFR domain, preventing ligand binding, and interrupting signal cascades (Herbst, 2004;Friedman and Stahl, 2009;Scott et al, 2012); (2) tyrosine kinase inhibitors binding to the intracellular EGFR domain and inhibiting the downstream effects of EGFR ligand binding (Herbst, 2004;Dassonville et al, 2007;Gazdar, 2009); and (3) delivery of drugs to cancer cells by fusion constructs containing EGF (Scott et al, 2012).…”

“…Based on the data obtained, numerous attempts have been made to create a drug where EGFR would be used as a vehicle for various agents, such as, for example, Auger-electron emitter 111 In, Staphylococcal enterotoxin A, etc. Several therapeutic approaches exploiting EGFR for this purpose have been evaluated in vitro and in vivo (Chen et al, 2002;Song et al, 2016;Zahaf et al, 2017;Liu et al, 2018).…”

Targeting oncogenic Ras by the Clostridium perfringens toxin TpeL

“…Recombinant wild-type and mutant Ras proteins were expressed in E. coli with an N-terminal GST-tag as described by [ 48 ]. PA and LFN-TpeL were expressed with a His-tag as described before [ 49 ].…”

Bacterial Toxins for Cancer Therapy

“…More recently, the transport of a new chimeric effector via the mPA-EGF and mPA-ZHER2 transporters was shown ( Figure 3 ). This new chimera consists of the N-terminal part of LF linked to the catalytic part of an effector from the Photorhabdus luminescence toxin TccC3hvr (aa 679–960) [ 61 ]. TccC3 is an ADP-ribosyltransferase, which modifies actin at threonine 148.…”

“…This modification blocks the interaction of actin monomers with thymosin-β4, causing uncontrolled acting clustering and cell death. The LFN-C3 construct was transported selectively into the EGFR-overexpressing mid-esophageal cells OE21 via the mPA-EGF transporter and in the HER2 overexpressing low esophageal OE33 cells via the mPA-ZHER2 transporter, selectively eliminating the targeted cells [ 61 ]. Mouse studies are definitely required to validate the specific action of these targeted toxins in vivo.…”