ChAcNLS, a Novel Modification to Antibody-Conjugates Permitting Target Cell-Specific Endosomal Escape, Localization to the Nucleus, and Enhanced Total Intracellular Accumulation.
The design of antibody-conjugates (ACs) for delivering molecules for targeted applications in humans has sufficiently progressed to demonstrate clinical efficacy in certain malignancies and reduced systemic toxicity that occurs with standard nontargeted therapies. One area that can advance clinical success for ACs will be to increase their intracellular accumulation. However, entrapment and degradation in the endosomal-lysosomal pathway, on which ACs are reliant for the depositing of their molecular payload inside target cells, leads to reduced intracellular accumulation. Innovative approaches that can manipulate this pathway may provide a strategy for increasing accumulation. We hypothesized that escape from entrapment inside the endosomal-lysosomal pathway and redirected trafficking to the nucleus could be an effective approach to increase intracellular AC accumulation in target cells. Cholic acid (ChAc) was coupled to the peptide CGYGPKKKRKVGG containing the nuclear localization sequence (NLS) from SV-40 large T-antigen, which is termed ChAcNLS. ChAcNLS was conjugated to the mAb 7G3 (7G3-ChAcNLS), which has nanomolar affinity for the cell-surface leukemic antigen interleukin-3 receptor-α (IL-3Rα). Our aim was to determine whether 7G3-ChAcNLS increased intracellular accumulation while retaining nanomolar affinity and IL-3Rα-positive cell selectivity. Competition ELISA and cell treatment assays were performed. Cell fractionation, confocal microscopy, flow cytometry, and Western blot techniques were used to determine the level of antibody accumulation inside cells and in corresponding nuclei. In addition, the radioisotope copper-64 ((64)Cu) was also utilized as a surrogate molecular cargo to evaluate nuclear and intracellular accumulation by radioactivity counting. 7G3-ChAcNLS effectively escaped endosome entrapment and degradation resulting in a unique intracellular distribution pattern. mAb modification with ChAcNLS maintained 7G3 nM affinity and produced high selectivity for IL-3Rα-positive cells. In contrast, 7G3 ACs with the ability to either escape endosome entrapment or traffic to the nucleus was not superior to 7G3-ChAcNLS for increasing intracellular accumulation. Transportation of (64)Cu when complexed to 7G3-ChAcNLS also resulted in increased nuclear and intracellular radioactivity accumulation. Thus, ChAcNLS is a novel mAb functionalizing technology that demonstrates its ability to increase AC intracellular accumulation in target cells through escaping endosome entrapment coupled to nuclear trafficking.
Departément de médecine nucléaire et radiobiologie, ‡Plateforme de synthèse de peptides et de sondes d'imageries, Faculté de médecine et sciences de la santé, and §Centre d'imagerie moléculaire de Sherbrooke (CIMS), Université de Sherbrooke , 3001 12e Avenue Nord, Sherbrooke, Québec J1H5N4, Canada.
Simon
S
Beaudoin
Departément de médecine nucléaire et radiobiologie, ‡Plateforme de synthèse de peptides et de sondes d'imageries, Faculté de médecine et sciences de la santé, and §Centre d'imagerie moléculaire de Sherbrooke (CIMS), Université de Sherbrooke , 3001 12e Avenue Nord, Sherbrooke, Québec J1H5N4, Canada.
Andreanne
A
Rondeau
Departément de médecine nucléaire et radiobiologie, ‡Plateforme de synthèse de peptides et de sondes d'imageries, Faculté de médecine et sciences de la santé, and §Centre d'imagerie moléculaire de Sherbrooke (CIMS), Université de Sherbrooke , 3001 12e Avenue Nord, Sherbrooke, Québec J1H5N4, Canada.
Olivier
O
Martel
Departément de médecine nucléaire et radiobiologie, ‡Plateforme de synthèse de peptides et de sondes d'imageries, Faculté de médecine et sciences de la santé, and §Centre d'imagerie moléculaire de Sherbrooke (CIMS), Université de Sherbrooke , 3001 12e Avenue Nord, Sherbrooke, Québec J1H5N4, Canada.
Marc-Andre
MA
Bonin
Departément de médecine nucléaire et radiobiologie, ‡Plateforme de synthèse de peptides et de sondes d'imageries, Faculté de médecine et sciences de la santé, and §Centre d'imagerie moléculaire de Sherbrooke (CIMS), Université de Sherbrooke , 3001 12e Avenue Nord, Sherbrooke, Québec J1H5N4, Canada.
Johan E
JE
van Lier
Departément de médecine nucléaire et radiobiologie, ‡Plateforme de synthèse de peptides et de sondes d'imageries, Faculté de médecine et sciences de la santé, and §Centre d'imagerie moléculaire de Sherbrooke (CIMS), Université de Sherbrooke , 3001 12e Avenue Nord, Sherbrooke, Québec J1H5N4, Canada.
Jeffrey V
JV
Leyton
D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects* / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D019826:Cholic Acid / Q000493:pharmacokinetics*; D011992:Endosomes / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D018796:Immunoconjugates / Q000494:pharmacology*; D053650:Interleukin-3 Receptor alpha Subunit / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D019913:Nuclear Localization Signals / Q000378:metabolism; D010455:Peptides / Q000378:metabolism
D000911:Antibodies, Monoclonal; C115022:IL3RA protein, human; D018796:Immunoconjugates; D053650:Interleukin-3 Receptor alpha Subunit; D019913:Nuclear Localization Signals; D010455:Peptides; D019826:Cholic Acid
antibody-conjugates; endosome escape; intracellular accumulation; nuclear localization