Homotrimerization Approach in the Design of Thrombospondin‑1 Mimetic Peptides with Improved Potency in Triggering Regulated Cell Death of Cancer Cells

In
order to optimize the potency of the first serum-stable peptide
agonist of CD47 (PKHB1) in triggering regulated cell death of cancer
cells, we designed a maturation process aimed to mimic the trimeric
structure of the thrombospondin-1/CD47 binding epitope. For that purpose,
an N-methylation scan of the PKHB1 sequence was realized to prevent
peptide aggregation. Structural and pharmacological analyses were
conducted in order to assess the conformational impact of these chemical
modifications on the backbone structure and the biological activity.
This structure–activity relationship study led to the discovery
of a highly soluble N-methylated peptide that we termed PKT16. Afterward,
this monomer was used for the design of a homotrimeric peptide mimic
that we termed [PKT16]3, which proved to be 10-fold more
potent than its monomeric counterpart. A pharmacological evaluation
of [PKT16]3 in inducing cell death of adherent (A549) and
nonadherent (MEC-1) cancer cell lines was also performed.