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Modular Conjugation of a Potent Anti-HER2 Immunotoxin Using Coassociating Peptides

Abstract : Immunotoxins are emerging candidates for cancer therapeutics. These biomolecules consist of a cell targeting protein combined to a polypeptide toxin. Associations of both entities can be achieved either chemically by covalent bonds or genetically creating fusion proteins. However, chemical agents can affect activity and/or stability of the conjugate proteins and additional purification steps are often required to isolate the final conjugate from unwanted by-products. As for fusion proteins, they often suffer from low solubility and yield. In this report, we describe a straightforward conjugation process to generate an immunotoxin using co-associating peptides (named K3 and E3), originating from the tetramerization domain of p53. To that end, a nanobody targeting the human epidermal growth factor receptor 2 (nano-HER2) and a protein toxin fragment from Pseudomonas aeruginosa Exotoxin A (TOX) were genetically fused to the E3 and K3 peptides. Entities were produced separately in E. coli in soluble forms and at high yields. The nano-HER2 fused to the E3 or K3 helixes (nano-HER2-E3 and nano-HER2-K3) and the co-assembled immunotoxins (nano-HER2-K3E3-TOX and nano-HER2-E3K3-TOX) presented binding specificity on HER2 overexpressing cells with relative binding constants in the low nanomolar to picomolar range. Both toxin modules (E3-TOX and K3-TOX) and the combined immunotoxins exhibited similar cytotoxicity levels compared to the toxin alone (TOX). Finally, nano-HER2-K3E3-TOX and nano-HER2-E3K3-TOX evaluated on various breast cancer cells were highly potent and specific to kill HER2-overexpressing breast cancer cells with IC50 values in the picomolar range. Altogether, we demonstrate that this non-covalent conjugation method using two co-assembling peptides can be easily implemented for modular engineering of immunotoxins targeting different types of cancers.
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Submitted on : Friday, November 13, 2020 - 10:50:37 PM
Last modification on : Wednesday, November 3, 2021 - 5:03:41 AM
Long-term archiving on: : Sunday, February 14, 2021 - 8:14:27 PM


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Audrey Stoessel, Nadja Groysbeck, Lucile Guyot, Lina Barret, Yves Nominé, et al.. Modular Conjugation of a Potent Anti-HER2 Immunotoxin Using Coassociating Peptides. Bioconjugate Chemistry, 2020, 31 (10), pp.2421-2430. ⟨10.1021/acs.bioconjchem.0c00482⟩. ⟨hal-03005245⟩



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