Targeting Nanomaterials to Head and Neck Cancer Cells Using a Fragment of the Shiga Toxin as a Potent Natural Ligand

Abstract

Head and Neck Cancer (HNC) is the seventh most common cancer worldwide with a 5-year survival from diagnosis of 50%. Currently, HNC is diagnosed by a physical examination followed by an histological biopsy, with surgery being the primary treatment. Here, we propose the use of targeted nanotechnology in support of existing diagnostic and therapeutic tools to prevent recurrences of tumors with poorly defined or surgically inaccessible margins. We have designed an innocuous ligand-protein, based on the receptor-binding domain of the Shiga toxin (ShTxB), that specifically drives nanoparticles to HNC cells bearing the globotriaosylceramide receptor on their surfaces. Microscopy images show how, upon binding to the receptor, the ShTxB-coated nanoparticles cause the clustering of the globotriaosylceramide receptors, the protrusion of filopodia, and rippling of the membrane, ultimately allowing the penetration of the ShTxB nanoparticles directly into the cell cytoplasm, thus triggering a biomimetic cellular response indistinguishable from that triggered by the full-length Shiga toxin. This functionalization strategy is a clear example of how some toxin fragments can be used as natural biosensors for the detection of some localized cancers and to target nanomedicines to HNC lesions.

Shiga Toxin-B Targeted Gold Nanorods for Local Photothermal Treatment in Oral Cancer Clinical Samples

“…Each "B" subunit can contact the receptor on the target cell membrane by triggering clustering upon coupling, thereby provoking membrane ruffling. 12,34-37 The ShTx "B" subunits are innocuous high-affinity GB3 natural ligands 12,38 that have been used to successfully drive fluorophores, 39,40 radionuclides, 41 drugs, 16,42 or even nanoparticles 17 to the cytoplasm of GB3 positive (GB3+ve) cells. Given these results, we proposed to use this fragment of the ShTx protein as a ligand to target multifunctional photoactivatable nanomaterials to GB3 positive (GB3+ve) squamous carcinoma cells.…”

“…15 Interestingly, several studies have localized the ShTx receptor in cancer cells of different origins. 13,[16][17][18][19][20] This glycosphingolipid, enriched in membrane microdomains known as lipid rafts, is overexpressed in many multidrug-resistant human tumor cells and is, therefore, a very interesting receptor for the treatment of malignant neoplasms.…”

Shiga toxin-targeted gold nanorods for head-neck cancer photothermal therapy in clinical samples

“…The ShTx "B" subunits are innocuous high-a nity GB3 natural ligands [7,24] that have been used to successfully drive uorophores, [25,26] radionuclides [27], drugs [11,28], or even nanoparticles [12] to the cytoplasm of GB3 positive (GB3+ve) cells. In the view of these results, we proposed to use this fragment of the ShTx protein as a ligand to target multifunctional photoactivatable nanomaterials to GB3 positive (GB3+ve) squamous carcinoma cells.…”

“…In the view of these results, we proposed to use this fragment of the ShTx protein as a ligand to target multifunctional photoactivatable nanomaterials to GB3 positive (GB3+ve) squamous carcinoma cells. To do this, we genetically engineered a customized protein fusing the ShTx "B" subunit to a cationic peptide to allow the electrostatic functionalization of nanomaterials following a bioconjugation method previously described (Experimental Section) [12,29]. In brief, the designed chimera protein named ShTxB:6xHis (hereafter ShTxB) containing the ShTx "B" subunit (UniProtKB ref.…”

“…The toxin penetrates the cytoplasm of the target cells bypassing the endolysosomal pathway, thus avoiding exposure to enzymatic and acid lysosomal media that would destroy the toxin and, in our case, the therapeutic agents [10]. Interestingly, several studies have localized the ShTx receptor in cancer cells of different origins [8,[11][12][13][14][15]. This glycosphingolipid, enriched in membrane microdomains known as lipid rafts, is overexpressed in many multidrug-resistant human tumor cells and is therefore a very interesting receptor for the treatment of malignant neoplasms.…”